Shares of SuperGen, Inc. (SUPG), which climbed as high as $2.89 on expectations for positive trial results, reached a new 52-week low of $1.71 in July 2010 following the negative top-line news.  SuperGen receives a 20-30% royalty on worldwide sales of Dacogen from its development and commercialization partners – Eisai in North America and Johnson & Johnson (JNJ) outside of North America.

Despite the negative top-line results, shares of SuperGen have since rebounded and reached a new 52-week high in April 2011.  Optimism may stem from the fact that both Eisai and Johnson & Johnson are continuing to analyze the data and planning to move forward with North America and European regulatory filings in 2011 based on the primary analysis and secondary endpoints.  Accordingly, investors will anxiously await the detailed Phase 3 results being presented on Monday, June 6, 2011 at ASCO to better gauge the likelihood of FDA approval in AML [Abstract #6504 “Results from a randomized phase III trial of decitabine versus supportive care or low-dose cytarabine for the treatment of older patients with newly diagnosed AML”].

Results from the Dacogen study may also be of interest to investors in Cyclacel Pharmaceuticals, Inc. (CYCC), which recently launched a multicenter, randomized, pivotal Phase 3 trial for the company’s sapacitabine oral capsules as a front-line treatment of elderly patients aged 70 years or older with newly diagnosed AML who are not candidates for intensive induction chemotherapy.  Unique among drugs available to treat AML patients, sapacitabine is the only oral agent in late-stage clinical development.  It is also the only candidate to progress into a pivotal study on the basis of survival data from a randomized Phase 2 study.  Historically, sponsors advanced molecules to pivotal development in AML based on Phase 2 studies with primary endpoints of complete remission [CR].

The pivotal Phase 3 study is being conducted under a Special Protocol Assessment [SPA] agreement that Cyclacel reached with the FDA.  The primary efficacy endpoint for the study is an improvement in overall survival from either of the two pairwise comparisons [Arm A versus Arm C, or Arm B versus Arm C] in the following three arms consisting of approximately 150 patients per arm:

• Arm A: sapacitabine administered in alternating cycles with Dacogen
• Arm B: sapacitabine administered alone
• Arm C: Dacogen administered alone

Cyclacel is testing the treatment regimen of sapacitabine administered in alternating cycles with Dacogen [Arm A] in an on-going pilot study, with data expected at ASCO 2011 [Abstract #6587 “Phase I/II study of sapacitabine and decitabine administered sequentially in elderly patients with newly diagnosed acute myeloid leukemia”].  Thirty-day and sixty-day mortality outcomes from this pilot study may be helpful in determining the odds of success in the Phase 3 pivotal study.  To put this in perspective, thirty-day mortality in AML patients aged 70 years or older ranged from 17% to 21% in a recently published Phase 3 study [Harousseau JL, et al, Blood, 2009:114:1166].  Accordingly, results from the pilot study that demonstrate thirty-day mortality with sapacitabine is equal or less than 21% could be encouraging for Cyclacel.

The Phase 3 study builds on promising 1-year survival observed in elderly patients aged 70 years or older with newly diagnosed AML or AML in first relapse enrolled in a Phase 2 study of single agent sapacitabine.  In a disease setting where patients are typically treated with chemotherapy agents like cytarabine for an average of 1 to 2 cycles, patients in Cyclacel’s Phase 2 study achieved a median of 12 cycles of treatment with sapacitabine.

In addition, approximately 45% of patients in the Phase 2 study had transformed into AML after being diagnosed with myelodysplastic syndromes [MDS] and were previously treated with Dacogen or Celgene Corporation’s (CELG) Vidaza® [azacitidine].  Only newly diagnosed AML patients are expected to be enrolled in the ongoing Phase 3 trial, none of whom had been previously treated with Dacogen or Vidaza and none of whom had relapsed, potentially increasing the odds for a successful trial.

Finally, Sunesis Pharmaceuticals, Inc. (SNSS) will also be presenting at ASCO [Abstract #TPS201, “Adaptive design of VALOR, a phase III trial of vosaroxin or placebo in combination with cytarabine for patients with first relapsed or refractory acute myeloid leukemia”].  Unlike the aforementioned frontline trials being conducted under SPA’s, Sunesis is studying vosaroxin in relapsed/refractory AML in an ongoing Phase 3 trial.  Approximately 450 patients will be randomized to receive either vosaroxin or placebo in combination with cytarabine.

Cytarabine, a generic chemotherapy drug introduced several decades ago, is already a critical part of the treatment for younger patients with AML who are fit to withstand its toxicity.  Unfortunately, several companies that make cytarabine have recently experienced production difficulties and others cannot make the drug fast enough to keep up with demand.  This has resulted in a severe shortage of cytarabine that has reportedly affected leukemia clinical trials being run by the Cancer and Leukemia Group B [CALGB].  Accordingly, investors will be looking to Sunesis for an update on enrollment in the VALOR Phase 3 trial to determine whether or not the cytarabine shortage has been a factor.

Beyond the aforementioned investigational therapies, a researcher in the field of oncology noted that newer, targeted agents will be required to advance the treatment of AML: “My personal opinion on AML affecting the elderly population is that the field is in need of a total revamp whereby certain chemotherapy agents need to be combined with targeted therapies to overcome drug resistance and provide meaningful survival data,” said Daruka Mahadevan, M.D. Ph.D., Director, Phase I Program, Arizona Cancer Center.  “If you can increase the survival of a 70-year old patient by ten years, that would be a real achievement.  Sapacitabine is interesting as it is an oral agent, while vosaroxin in combination of cytarabine may provide short term control – but is unlikely to provide a survival benefit.”

Table 1. Old Versus New Paradigm in Biotechnology Collaborations

In addition, the negative considerations from large pharmaceutical partnerships are often overlooked, which begs the question: is it better to partner, or go alone?  To help address the topic, this article focuses on the oncology segment of the life science industry – one of the most popular therapeutic areas for partnering and merger & acquisition [M&A] activity.

Luck Vs Skill

Prior to addressing the question of whether or not a small biotechnology company should collaborate with a larger pharmaceutical organization, we solicited investor views regarding the process of corporate partnering.  Some of the feedback indicates there is a lack of transparency.

“As an investor, partnering activity is the most opaque part of our companies’ business,” said David Sable, portfolio manager, Special Situations Life Sciences Fund.  “Every small biotech CEO tries to create an image of limitless interest on the part of big pharma in each of the company’s projects, a dynamic that will inevitably result in a value-maximizing transaction.  Many management teams deliver on these promises; in retrospect, however, at least as many seem to have parked their molecule in the front yard with a ‘For Sale’ sign and hoped for the best.  While we can validate the importance of a molecular pathway, double-check market size predictions, run our own statistics and reality-check pricing assumptions, we have no way to identify talent in business development.”

Left at the Altar

One of the most important negative considerations for biotechnology companies looking to partner is that large pharmaceutical companies often shift resources and the focus of their pipeline development candidates over time, which may put their collaborators at risk.  Although sometimes done for strategic reasons rather than due to new clinical insight, the sudden departure of a large pharmaceutical partner can reflect poorly on an otherwise promising product candidate.

For example, Celldex Therapeutics, Inc. (CLDX) announced in September 2010 that the company would regain full worldwide rights to develop and commercialize rindopepimut [CDX-110] from Pfizer, Inc. (PFE).  The companies had entered into a global development and commercialization agreement in April 2008 for rindopepimut, an experimental therapeutic cancer vaccine that targets the tumor-specific molecule epidermal growth factor receptor variant III in patients with glioblastoma multiforme.  Pfizer informed Celldex that the rindopepimut program was no longer a strategic priority of Pfizer and terminated the agreement despite the fact that the product candidate met or exceeded all pre-determined safety and efficacy objectives across three clinical studies.  Shares of Celldex, which traded as high as $9.49 during 2010, reached a 52-week low of $2.91 on the news.

More recently, Transgene (TNG.PA) announced on February 22, 2011, that Roche Holding (ROG.VX) terminated their 2007 agreement under which Roche had been granted exclusive global development and commercialization rights to TG4001/RG3484, a therapeutic vaccine candidate currently in a 200 patient Phase IIb study to treat notably high grade cervical intraepithelial neoplasia [CIN] lesions [CIN2/3] caused by human papilloma virus [HPV] infection.  While Transgene stated that Roche’s decision to terminate the license agreement was based on strategic reasons and wasn’t data driven, the company’s shares reached a 52-week low on the news.

Hopes and Dreams Vs Revenue Streams

Another potential negative is that by partnering a product candidate, the “hope and dream” multiple of a potential partnership or acquisition may be replaced by the realities of a “revenue stream,” such as milestone payments and future product royalties.  By discounting the economics of a partnership deal for certain risk factors, investors can assign a net present value to the company that may be quite different than the speculative valuation in the absence of a partnership.  Representing a unique opportunity to review the effect of partnering on market capitalization, three separate deals were announced for late-stage product candidates aimed at treating prostate cancer during 2009, while two companies have remained independent [see Table 2].

As the first transaction announced that year, Johnson & Johnson’s (JNJ) acquisition of Cougar Biotechnology for nearly $1 billion in cash in May 2009 initially looked attractive.  However, following approval of Provenge® [sipuleucel-T] in April 2010, the market capitalization of Dendreon Corporation (DNDN) exceeded $7 billion, which demonstrates the potential benefit of remaining independent or retaining worldwide rights.  In contrast, more than a year after partnering their late-stage programs, the market valuations of two other companies, Medivation, Inc. (MDVN) and OncoGenex Pharmaceuticals, Inc. (OGXI), are $605 million and $150 million, respectively.

Using Dendreon’s valuation as an example, it isn’t surprising that Bavarian Nordic A/S (BAVA.CO) announced earlier today that the company is reviewing alternate options to maximize value for shareholders and fund the pivotal Phase 3 trial of its “off-the-shelf” therapeutic vaccine product candidate Prostvac® on its own.  Keeping its options open, however, Bavarian Nordic is exploring opportunities to pursue independent development in parallel with continuing partnership discussions.

Table 2. Late-stage Prostate Cancer Programs

A Means to an End

The biggest argument against partnering is the fact that some of the most successful biotechnology companies to date are those that have commercialized their own products, such as Amgen, Inc. (AMGN), Celgene Corporation (CELG), and several others.

“Celgene is a unique example of success by taking a slightly different approach,” said Charles Duncan, managing director and senior biotech analyst at JMP Securities LLC.  “The company built a pipeline and worldwide infrastructure for Revlimid® [lenalidomide] that was funded and supported through its early sales of Thalomid® [thalidomide].”

“We viewed partnering our lead product as a critical strategic decision that would shape the company and significantly impact our vision,” said Sol J. Barer, Ph.D., Executive Chairman of Celgene Corporation.  “We felt that our pursuing the development of Revlimid worldwide alone was the best option consistent with our vision a of becoming a major global biopharmaceutical company over the next few years.  We clearly recognized the short versus long term trade-offs in the decision; nevertheless, our belief in the product and in our ability to manage the product globally was important in our decision not to partner.”

Some companies have also partnered a specific program in certain geographies or disease settings and use the validation and resulting economics to help advance their own pipeline – sometimes even in competitive areas.  For example, Amgen originally developed Epogen® [epoetin alfa], which the company commercialized as a treatment for anemia in dialysis patients and partnered non-dialysis rights with Johnson & Johnson [sold as Procrit®].  Amgen later developed and commercialized Aranesp® [darbepoetin alfa], an erythropoiesis stimulating protein with a longer half-life and increased biologic activity that was not partnered.

Similarly, Oncothyreon, Inc. (ONTY) has granted a license to Merck KGaA of Darmstadt, Germany for the clinical development, manufacturing, and marketing of Stimuvax®.  Oncothyreon is eligible for cash payments based on the achievement of certain process transfer events, regulatory submissions in first and second cancer indications, regulatory approval for first and second cancer indications, and for sales milestones.  Oncothyreon will also receive a royalty based on net sales.  If successful in the clinic, Stimuvax could also help validate another Oncothyreon product candidate, ONT-10, which is a completely synthetic MUC1-based liposomal glycolipopeptide cancer vaccine that could compete with Stimuvax.  Merck KGaA has a right of first negotiation with respect to ONT-10.

Geographically Undesirable

Although selective encumbered assets can still attract buyers, partnering a product candidate in certain geographies with one large pharmaceutical company may preclude an acquisition by another that is only interested in worldwide rights or control of key markets.  On the other hand, some partnerships can later lead to an acquisition – a strategy employed by Bristol-Myers Squibb Company (BMY) on more than one occasion.

For example, Bristol-Myers Squibb and Medarex, Inc. formed a worldwide collaboration in 2004 valued at more than $530 million to develop and commercialize Yervoy® [ipilimumab, MDX-010], which was in Phase III clinical development at the time for the treatment of metastatic melanoma and multiple Phase II clinical trials in other oncology indications.  In 2009, Bristol-Myers Squibb acquired Medarex for $16.00 per share, a 90% premium over the prior day’s closing price of $8.40 per share, for an aggregate purchase price of approximately $2.4 billion.

What started as a lawsuit for infringement of its patents related to fusion protein technology in 2006, ZymoGenetics, Inc. signed a deal with Bristol-Myers Squibb in 2009 worth more than $1.1 billion for PEG-Interferon lambda, a novel type 3 interferon in Phase Ib development for the treatment of Hepatitis C, and its related development program.  The following year, Bristol-Myers Squibb acquired ZymoGenetics for $9.75 per share in cash [an 84% premium to the prior day close] in a transaction valued at approximately $885 million.

While ultimately thwarted by Eli Lilly & Co.’s (LLY) superior offer in October 2008, Bristol-Myers also attempted to acquire its partner ImClone Systems.  Back in September 2001, Bristol-Myers had entered into an agreement with ImClone to co-develop and co-promote Erbitux® [cetuximab, IMC-C225] in the United States, Canada and Japan.

All that Glitters is not Gold

Maintaining worldwide rights and commercializing a product without a partner doesn’t necessarily translate into a lofty market valuation.  Several companies have struggled to commercialize oncology products on their own.

Allos Therapeutics, Inc. (ALTH) developed Folotyn® [pralatrexate injection], a folate analogue metabolic inhibitor, and began commercializing the product in the U.S. for the treatment of patients with relapsed or refractory peripheral T-cell lymphoma [PTCL] in October 2009.  Since the product’s launch, Folotyn sales have been below Wall Street analyst’s expectations and shares of Allos recently reached a 52-week low of $2.64.

Despite an inauspicious launch in the U.S., some analysts believe that Allos may finally be executing on a regional strategy with the recent filing of a Marketing Authorisation Application for European approval and the potential for a partner in Asia as highlighted during the company’s recent quarterly teleconference with investors.

“If Allos gets traction with an ex-U.S. approval and partnership, investor sentiment will most certainly improve as this will provide some external validation on the viability of a regulatory path and market opportunity in PTCL, despite it being a rare disease and there being emerging potential competition from Celgene’s Istodax® [romidepsin],” said Charles Duncan.  “At this point, all but the most patient, value-oriented investors have extricated themselves from the Allos story due to what we believe to be a lack of confidence in senior management, and having another company to shoulder the risk ex-U.S. will provide a much-needed boost to the capabilities and capital needed to profitably market Folotyn.  Perhaps this too could be an example where a collaboration discussion turns into an acquisition, although we anticipate that should such a scenario materialize, it would likely involve contingent-value rights [CVR’s] given the uninspiring early revenue trajectory.”

Summary

Looking ahead, the trade-off between equity dilution and asset dilution represents an important crossroad that many late-stage biotechnology companies will face in the near future [see Table 3 for a select list].  While one size doesn’t fit all, the fact that Dendreon has achieved the largest market valuation of any company in the late-stage prostate cancer segment of the market by commercializing its product without a partner helps support the notion that going alone may provide the highest value to stakeholders.  Such a strategy requires that the company can access resources and capital to develop and launch its product globally.  If not, a selective or global partnership may be the next best options – provided the terms are attractive and that there is a remaining pipeline to be leveraged in the future.  In the end, whether a company proceeds alone or with a partner, there is an attractive landscape of motivated buyers for late-stage and marketed products that may ultimately lead to M&A.

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Table 3. Select Companies with Phase III Oncology Programs Not Yet Partnered

• View the company’s fact sheet (PDF)

Standard frontline therapy for AML patients under the age of 60 consists of cytarabine  [AraC] combined with an anthracycline [such as daunorubicin or idarubicin] in what is commonly referred to as the 7+3 regimen.  While 45% of elderly patients with AML [70+ years old] achieved a complete response [CR] using this regimen, there was no improvement in overall survival and more than a third of patients died within the first eight weeks of treatment according to a recent study published in the journal Blood[i].  This is consistent with the CR rates of 40%–60% with conventional chemotherapy and disease-free survival of less than 20% at three years referenced in the literature[ii].

Since more than half of AML cases occur in patients over 60 years old, there is a need to develop better frontline therapies in this setting.  With five agents being investigated as frontline therapy for elderly AML patients in late-stage trials, the purpose of this article is to compare and contrast these programs – several of which have near-term catalysts for investors.

Hypomethylating Agents

SuperGen, Inc. (SUPG), Eisai Co. Ltd. (ESALF), and Johnson & Johnson (JNJ)

On June 30, 2010, preliminary results from a Phase III trial of Dacogen® [decitabine] as a frontline treatment for elderly patients [65+ years old] with AML were released.  While Dacogen did not meet the primary endpoint of overall survival, a trend was reported to be evident.  However, the failure to demonstrate an improvement in overall survival was surprising given the favorable Phase II results and the fact that the comparator arm received low dose AraC instead of the aforementioned 7+3 regimen.  Low dose AraC predominantly works in patients with favorable cytogenetics, so it should have been relatively easy for Dacogen to demonstrate a survival benefit.

Shares of SuperGen, which climbed as high as $2.89 on expectations for positive trial results, reached a new 52-week low of $1.71 in July.  Supergen receives a 20-30% royalty on worldwide sales of Dacogen from its development and commercialization partners – Eisai in North America and Johnson & Johnson outside of North America.

While investors appear to be discounting approval of Dacogen as a frontline therapy for elderly AML, there may be reasons for optimism.  For example, both Eisai and Johnson & Johnson are continuing to analyze the data and planning to move forward with North America and European regulatory filings in 2011 based on the primary analysis and secondary endpoints.  In addition, the Phase III study was conducted under a special protocol assessment [SPA] with the U.S. Food and Drug Administration [FDA].

Celgene Corporation (CELG)

In view of Dacogen’s negative Phase III trial results, investors may be skeptical about Vidaza® [azacitidine], another hypomethylating agent currently approved for the treatment of myelodysplastic syndromes [MDS], a pre-cancerous condition that can often progress to AML.  According to ClinicalTrials.gov [Identifier NCT01074047], Celgene is currently enrolling patients in a Phase III, multicenter, randomized, open-label, study of Vidaza versus conventional care regimens for the frontline treatment of elderly patients [65+ years old] with AML.

In December 2008, the European Commission granted marketing authorization for Vidaza as a treatment for patients with higher-risk MDS, chronic myelomonocytic leukemia [CMML], and MDS that transforms into AML with a blast percentage of 20-30% in the peripheral blood or bone marrow.  While Vidaza demonstrated a clinically relevant increase in median survival of 9.4 months [24.4 vs. 15 months] in these settings[iii], it is unclear how the drug will work in AML de novo patients with a higher blast percentage [greater than 50%] that represent half of the elderly patient population.  In view of the fact that Dacogen is more myelosuppressive than Vidaza [see Table 1], and for this reason may be preferred over Vidaza for off-label use in AML, the recent failure of Dacogen only adds to this uncertainty.

Table 1. Percentage of Patients with Myelosuppression from Prescribing Information

Monoclonal Antibodies

Seattle Genetics, Inc. (SGEN)

Seattle Genetics is developing SGN-33 [lintuzumab], an unconjugated IgG1 antibody for the treatment of AML.  Lintuzumab has been shown to induce cell death by both complement and/or antibody-directed cellular cytotoxicity, or as a direct effect of the engagement of the CD33 receptor, which is expressed in most leukemic blast cells but also in normal hematopoietic cells.

In a Phase II study in relapsed/refractory AML patients, single agent lintuzumab demonstrated efficacy in patients with advanced AML; however, the positive effects were confined to patients with low disease burden [blast percentage 5% to 30%].  This suggested that additional development of this agent would be best achieved by combining lintuzumab with chemotherapy.  However, while the addition of lintuzumab to salvage induction chemotherapy was safe, it did not result in a statistically significant improvement in response rate or survival in patients with refractory/relapsed AML in a subsequent Phase III trial[iv].

Seattle Genetics is now conducting a 210 patient Phase IIb study in frontline treatment of elderly patients [60+ years old] with AML with results expected in the August to October 2010 timeframe.  See ClinicalTrials.gov [Identifier NCT00528333] for more information.

While lintuzumab relies on a different mechanism of action, investor’s are understandably skeptical about the success of another anti-CD33 monoclonal antibody in AML.  In June 2010, Pfizer, Inc. (PFE) agreed to withdraw Mylotarg® [gemtuzumab ozogamicin] from the U.S. market, effective October 15.  Mylotarg is an IgG4 monoclonal antibody to CD33 linked to a cytotoxic agent from the class of calicheamicins.  Developed by Wyeth, the drug was fast-tracked to treat patients ages 60 and older with recurrent AML who were not candidates for other chemotherapy.  The FDA approved Mylotarg in May 2000 based upon a surrogate endpoint due to the fact it treated relapsed disease with no other viable therapy.

Four years later, a confirmatory trial was begun to confirm the results of the 142 patients who participated in the three previous clinical trials.  The 2004 trial showed that adding Mylotarg to existing chemotherapy for the treatment of AML provided no benefit and even showed a higher death rate.

Nucleoside Analogs

Genzyme Corporation (GENZ)

In September 2009, the FDA’s Oncologic Drugs Advisory Committee [ODAC] voted 9 to 3 that a randomized, controlled trial is needed to support the proposed label expansion for Clolar® (clofarabine) as a frontline treatment for elderly [60+ years old] patients with AML.  Consistent with the decisions for both Johnson & Johnson’s Zarnestra® [tipifarnib] and Vion Pharmaceuticals’ Onrigin® [laromustine], the committee determined that single-arm clinical study results were not sufficient for approval.

Despite the setback, Genzyme stated in a press release that the company remains committed to the clinical development of clofarabine in this patient population and that the drug is being investigated in clinical trials by most of the leading AML experts and major cooperative leukemia investigation groups in the United States and Europe.

Beyond the frontline setting, Genzyme is also conducting a randomized Phase III trial comparing clofarabine in combination with AraC to AraC alone in relapsed and refractory adult AML patients 55 years old or older [ClinicalTrials.gov Identifier NCT00317642]. Results are expected in 2011.

Note: At the time of writing, Sanofi-Aventis (SNY) has offered to acquire Genzyme for $69 per share.

Cyclacel Pharmaceuticals, Inc. (CYCC)

Cyclacel is developing sapacitabine for the treatment of AML, MDS and non-small cell lung cancer [NSCLC].  Sapacitabine is unique among the frontline, elderly AML landscape as it represents the only oral agent in late-stage clinical development and the only product candidate to demonstrate a survival benefit in a randomized study.

In December 2009, Cyclacel reported interim results from an ongoing Phase II study involving 60 patients aged 70 or older with either untreated AML [80%] or AML in first relapse [20%] randomized across three dosing schedules of sapacitabine [ClinicalTrials.gov Identifier NCT00590187].  The three-day dosing schedule in Arm C was selected for further clinical development in elderly patients with de novo AML based on a 1-year survival rate of 30% and an overall response rate of 35%.

In the first quarter of 2010, Cyclacel submitted a SPA request for a randomized, registration-directed, Phase III study of sapacitabine in elderly patients with AML and, pending the response, expects to initiate a pivotal Phase III study in 2010.

Summary

While many companies are developing therapies for AML [see Table 2], there is a need to focus on better frontline therapies for elderly patients given the lack of efficacy and significant toxicity associated with the current 7+3 treatment regimen.  Investors will be watching the following catalysts to help handicap which of the five product candidates [decitabine, azacitidine, clofarabine, sapacitabine, or lintuzumab] will win the race and become the first agent approved by the FDA in this setting:

• Phase IIb results for lintuzumab expected in the August to October 2010 timeframe
• FDA response to SPA request for Phase III study of sapacitabine; initiation of pivotal Phase III study in 2010
• Supplemental new drug application [sNDA] for decitabine by March 31, 2011 and subsequent response from FDA
• Results from frontline clofarabine clinical trials by AML experts and major cooperative leukemia investigation groups in the United States and Europe; relapsed/refractory AML Phase III results in 2011
• Phase III results for azacitidine expected around 2013

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Table 2. Late-stage Therapeutic Landscape for AML

References

[i] Kantarjian H, Ravandi F, O’Brien S, Cortes J, Faderl S, Garcia-Manero G, Jabbour E, Wierda W, Kadia T, Pierce S, Shan J, Keating M, Freireich EJ.  Intensive chemotherapy does not benefit most older patients (age 70 years or older) with acute myeloid leukemia. Blood. 2010 Jul 28. [Epub ahead of print]

[ii] Amadori S, Suciu S, Willemze R, Mandelli F, Selleslag D, Stauder R, Ho A, Denzlinger C, Leone G, Fabris P, Muus P, Vignetti M, Hagemeijer A, Beeldens F, Anak O, De Witte T; EORTC leukemia group; GIMEMA leukemia group.  Sequential administration of gemtuzumab ozogamicin and conventional chemotherapy as first line therapy in elderly patients with acute myeloid leukemia: a phase II study (AML-15) of the EORTC and GIMEMA leukemia groups.  Haematologica. 2004 Aug;89(8):950-6.

[iii] Edlin R, Connock M, Tubeuf S, Round J, Fry-Smith A, Hyde C, Greenheld W.  Azacitidine for the treatment of myelodysplastic syndrome, chronic myelomonocytic leukaemia and acute myeloid leukaemia. Health Technol Assess. 2010 May;14 Suppl 1:69-74.

[iv] Eric J. Feldman, Joseph Brandwein, Richard Stone, Matt Kalaycio, Joseph Moore, Julie O’Connor, Nancy Wedel, Gail J. Roboz, Carole Miller, Raj Chopra, Joseph C. Jurcic, Randy Brown, W. Christopher Ehmann, Philip Schulman, Stanley R. Frankel, Daniel De Angelo, David Scheinberg.  Phase III Randomized Multicenter Study of a Humanized Anti-CD33 Monoclonal Antibody, Lintuzumab, in Combination With Chemotherapy, Versus Chemotherapy Alone in Patients With Refractory or First-Relapsed Acute Myeloid Leukemia. Journal of Clinical Oncology, Vol 23, No 18 (June 20), 2005: pp. 4110-4116.

While a comprehensive preview of AACR is beyond the scope of this article, we note that two companies working in the area of cyclin-dependent kinase [CDK] inhibition made headlines in the months leading up to AACR.  Further evidence of interest in the area is demonstrated by the fact that the 2001 Nobel Prize in Physiology or Medicine was awarded for the discovery of CDKs and cyclins and the complete description of cyclin and cyclin-dependent kinase mechanisms. 

By selectively interrupting the cell cycle regulation in cancer cells, inhibition of CDKs represents a promising strategy for cancer therapy.  Accordingly, with more than 50 abstracts related to CDK inhibition scheduled for presentation at this year’s AACR annual meeting, we provide an overview of the target and highlight some of the companies and programs being discussed.

CDK overview

Each time a cell divides it undergoes a series of events collectively known as the cell cycle.  Controlled and regulated cellular division is a normal part of cell physiology. 

Cancer is characterized by uncontrolled cellular division and growth, which can be caused by mutations in DNA resulting in the overexpression of cancer-promoting oncogenes or repression of tumor suppressor genes.  There are many examples of oncogenes and tumor suppressor genes but some of the more common ones include signaling proteins [PI3K], receptors [HER2], and DNA damage and repair regulating proteins that control cell cycle check-points such as p53 and BRCA. 

CDKs are a group of signaling kinases that play a direct role in the regulation and progression of the cell cycle.  CDK activity is dependent on the availability of their regulatory subunits called cyclins, which CDKs phosphorylate in order to stop cell cycle progression in cancerous cells.  Production and destruction of cyclins are tightly regulated in coordination with cell cycle progression.  Targeting CDK/cyclin macromolecular complexes is an attractive strategy for the design of novel anticancer drugs. 

There are over a dozen known CDK/cyclin complexes.  The most extensively studied subtypes are CDK2/cyclin E, CDK2/cyclin A, CDK7/cyclin H, and CDK9/cyclin T which are key components of the p53 pathway and CDK4 and CDK6 interacting with cyclin D1, which are key components of the retinoblastoma or Rb pathway.

Many tumor mutations interfere or deregulate the tight control of cyclin-CDK interactions leading to overactive CDKs, resulting in continuous cellular proliferation or unscheduled re-entry into the cell cycle.  In addition, deregulated CDK activity can result in genomic and chromosome instability, a feature observed in many advanced or aggressive tumors.

Early Failures

First generation, pan-CDK inhibitors have not demonstrated improved clinical outcomes.  Reasons for early failures include non-specific drug targets or suboptimal dosing and scheduling.    Also, pan-CDK inhibitors may not have an acceptable pharmacological window due to high toxic side effects or limited efficacy. 

For example, CDK7, CDK8, and CDK9 play a role in DNA transcription.  While it may be advantageous to target these CDK/cyclins as part of a multikinase drug profile, strong inhibition may result in the broad disruption of transcription, which is not desirable. 

This may have been the case with BMS-387032 [subsequently known as SNS-032], a small molecule cell-cycle modulator that targets CDKs 1, 2, 4, 7, and 9.  The compound demonstrated significant safety risks in Phase I studies conducted by Bristol-Myers Squibb (BMY), including increases in certain phases of the cardiac cycle, known as the QT interval. 

In 2005, Sunesis Pharmaceuticals, Inc. (SNSS) acquired rights to BMS-387032 for an up-front payment of $8 million in Sunesis’ stock, future milestone payments totaling $78 million, and royalties on net sales.  However, in December 2008, Sunesis notified Bristol-Myers that the company was terminating the license agreement for SNS-032 after no responses demonstrating efficacy were observed in a Phase I trial.

Next generation CDK inhibitors target select CDK sub-types and have shown improved potency along with other drug-like properties.  The various CDK sub-types are active at different points within the cell cycle and discrete cancers are dependent on specific CDK sub-types.  Therefore, each CDK inhibitor sub-type may be relevant to different tumors or genetic mutations. 

For example, CDK4 is frequently deregulated in glioblastoma and CDK2 activity is commonly altered in colon cancer.  Recently published evidence implicates certain cyclins and in particular cyclin E, the partner of CDK2, as a mediator of acquired resistance in several cancers, such as lung and breast cancer.  Some of these next-generation programs are highlighted below [also refer to Table 1]:

Pfizer, Inc. (PFE)

In late March 2010, Pfizer made headlines with a preclinical study published in the journal Cancer Research.  Results from the study demonstrated that PD-0332991, a drug being developed by Pfizer, could arrest the growth of glioblastoma multiforme [GBM] in animals.  PD-0332991 is an oral agent that inhibits certain CDKs, mainly CDK4 and CDK6.  Six abstracts related to PD-0332991 are scheduled for presentation at AACR.  Pfizer is managing and funding all clinical development of PD-0332991, which the company licensed from Onyx Pharmaceuticals, Inc. (ONXX).  PD-0332991 is the subject of various clinical trials in multiple myeloma, NHL, mantle-cell lymphoma, glioblastoma and breast cancer. 

Cyclacel Pharmaceuticals, Inc. (CYCC)

Cyclacel Pharmaceuticals, which is developing a clinical stage CDK inhibitor candidate, also made headlines earlier this year.  The company’s oral compound seliciclib [CYC202 or R-roscovitine], inhibits CDK2/E, CDK2/A, CDK7/H, and to a lesser degree CDK9/T.  Seliciclib is currently in Phase IIb clinical trials for non-small cell lung cancer [NSCLC] and nasopharyngeal cancer.

Shares of Cyclacel Pharmaceuticals jumped from $1 to more than $4 in January 2010 when independent investigators published data in the peer-reviewed journal Clinical Cancer Research showing that both seliciclib and a second-generation CDK inhibitor from Cyclacel reversed resistance to lung cancer cells with K-Ras or N-Ras mutations.  Cancers with Ras-activating mutations are thought to be among the most difficult to treat and are not responsive to modern targeted drug therapy, such as EGFR inhibitors.  The data also showed that lung cancer cells are addicted to cyclin E/CDK2.  Cyclacel expects to report top line results from its APPRAISE NSCLC Phase IIb trial with seliciclib later this year. 

A different investigator group also recently published data in the peer-reviewed journal Clinical Cancer Research demonstrating that seliciclib reversed resistance to the aromatase inhibitor Femara® [letrozole].  Seliciclib killed hormone receptor-positive breast cancer cells that had become insensitive to the effects of letrozole because of over expression of low molecular weight Cyclin E. 

At AACR, Cyclacel is introducing a second-generation CDK product candidate, which is currently in investigational new drug [IND]-directed development.  The undisclosed molecule is a second generation oral CDK inhibitor with increased potency.  Three abstracts related to both seliciclib and the second-generation compound are scheduled for presentation at AACR.

Sanofi-Aventis SA (SNY)

Sanofi-Aventis is developing its lead CDK inhibitor, flavopiridol [HMR-1275, alvocidib] for the treatment of both solid and hematologic malignancies.  Flavopiridol is a pan–CDK inhibitor that blocks CDK9, -2, -4, and -6 at nanomolar concentrations.  Published data from flavopiridol clinical trials suggest that its main toxicities are induction of neutropenia and secretory diarrhea.  Phase II studies of flavopiridol as a single agent have been completed in metastatic melanoma, endometrial adenocarcinoma, and multiple myeloma demonstrating limited efficacy as a monotherapy.  However, flavopiridol has shown promise as a combination therapy, with the best responses observed in CLL patients in combination with fludarabine and cyclophosphamide.  Four abstracts related to flavopiridol are scheduled for presentation at AACR.

Merck & Co., Inc. (MRK)

Merck is developing its lead CDK inhibitor, SCH 727965 [dinaciclib], for multiple indications including solid tumors, NHL, multiple myeloma, ACL, and ALL.  SCH 727965 is an intravenously-delivered CDK1, CDK2, CDK5, and CDK9 inhibitor.  The drug is administered by a 2-hour IV infusion once every 21 days.  Merck is currently recruiting patients for a Phase II study evaluating SCH 727965 to determine the activity of SCH 727965 in patients with breast cancer and in patients with lung cancer compared to standard treatment, capecitabine and erlotinib respectively.  One abstract regarding the activity of SCH 727965 in cell lines for childhood cancers is scheduled for presentation at AACR.

Bayer (BAY.DE)

Bayer will introduce its CDK inhibitor, BAY 1000394, in an abstract scheduled for presentation at AACR.  BAY 1000394 is a nanomolar pan-CDK inhibitor targeting CDK1/Cyclin B, CDK2/Cyclin E, CDK4/Cyclin D1, and CDK9/Cyclin T1.  The maximum tolerated dose for BAY 1000394 was found to be 2.0 mg/kg on QD schedule and 2.5 mg/kg on a BID intermittent schedule.  BAY 1000394 is being tested in a broad range of histological tumor subtypes.

Tragara Pharmaceuticals (private)

Tragara Pharmaceuticals is developing TG02 [also known as SB1317], an oral multi-kinase inhibitor that targets CDK 1, 2, 7 and 9, as well as two other kinases – JAK2 and FLT3.  TG02, which was licensed from S*BIO Pte Ltd in January 2009, is being prepared for IND filing in Q2 2010 with plans to proceed in hematology and solid tumors.  Tragara recently received a $1 million grant form the Multiple Myeloma Research Foundation [MMRF] to fund the early-stage drug development TG02 in treating multiple myeloma.  One abstract regarding the activity of TG02 in leukemia cell lines is scheduled for presentation at AACR.

Conclusion

 CDKs play a pivotal role in a cell’s entry into division; de-regulated CDK activity is a well-documented player in tumor progression and represents an attractive therapeutic anti-cancer option.   However, first generation CDK inhibitors have not demonstrated improved clinical outcomes.  Next generation CDK inhibitors, such as those being discussed at AACR, are CDK sub-type specific and have shown improved potency along with other drug like properties.  In addition, next generation CDKs are demonstrating their importance in several difficult to treat cancers, such as those dependent on Ras-activating mutations.

Table 1: Abstracts for CDK Inhibitors at AACR

* MD Becker Partners reporting live from the JP Morgan Healthcare Conference

This week, nearly 6,500 registrants gathered in San Francisco, California for the JP Morgan Healthcare Conference to hear 25-minute presentations from 338 life science companies.  For industry executives and investors, the annual event serves as a good barometer for the rest of the year.

We roamed the familiar halls of the Westin St. Francis Hotel to assess the mood among participants and also monitored online media commentaries throughout the event.  In general, there was a flurry of activity, the plane flights and networking receptions were crowded as usual, and several industry observers “Tweeted” a sense of optimism for 2010.  However, we sought to construct a less subjective assessment by analyzing year-over-year statistics from the conference.

Accordingly, we extensively reviewed company press releases issued during the JP Morgan Healthcare Conference in both 2009 and 2010, with a particular focus on identifying the number of merger & acquisitions, licensing & partnering transactions, and financing deals announced each year during the four day event.

Merger and Acquisitions

In contrast to the absence of any significant M&A deals announced during the JP Morgan Healthcare Conference in 2010, several large M&A transactions with an aggregate value of $702 million were disclosed during the first two days of the event in 2009 [January 12-15, 2009].  The largest deal went to Cephalon, Inc. (CEPH), which announced an agreement providing the company with an option to purchase all outstanding capital stock of Ception Therapeutics, Inc., a privately held biopharmaceutical company.  Under the terms of the option agreement, Cephalon paid Ception $100 million upfront for the option.  If Cephalon exercises its option, the company will purchase all of the outstanding capital stock of Ception for $250 million along with additional payments related to clinical and regulatory milestones.  Other transactions announced that year included:

• Medtronic, Inc.’s (MDT) acquisition of privately held Ablation Frontiers, Inc. for an initial payment of $225 million plus potential additional payments contingent upon achievement of certain clinical milestones
• The Medicines Company’s (MDCO) merger agreement with Targanta Therapeutics Corporation for $42 million in cash and additional regulatory and commercial milestone payments
• NuVasive, Inc.’s (NUVA) option to acquire Progentix Orthobiology BV, a Netherlands based company focused on developing novel orthobiologics, consisting of an upfront investment of $15 million along with the obligation to purchase the remaining equity of Progentix for $45 million upon accomplishment of certain development milestones [with additional potential payments of up to $25 million upon the achievement of additional milestones and based upon NuVasive's sales success]

Licensing and Partnering

Kicking off the JP Morgan Healthcare Conference in 2010, privately held KaloBios Pharmaceuticals, Inc. announced a $290 million agreement with Sanofi Pasteur, the vaccines division of the sanofi-aventis Group (SNY), for the development and commercialization of KB001, an investigational new biologic for the treatment or prevention of Pseudomonas aeruginosa [Pa] infections.  KaloBios, which is developing first-in-class human antibody therapeutics that offer advantages over other methods of human antibody creation in terms of immunogenicity, potency, and manufacturing yields, will receive an upfront payment of $35 million, plus development, regulatory and commercial milestones for a potential further $255 million, as well as royalties on eventual product sales.

While other licensing and partnering transactions were announced during the JP Morgan Healthcare Conference in 2010, they were substantially smaller or specific financial terms were not disclosed.  These include:

• Proteus Biomedical Inc. announced an exclusive worldwide license and collaboration agreement with Novartis AG (NVS) to develop and commercialize pharmaceutical products that incorporate Proteus’ novel sensor-based technologies in the field of organ transplantation along with certain option rights in cardiovascular and oncology product applications.  Under the terms of the agreement, Novartis will make upfront cash and equity investments in Proteus totaling $24 million and Proteus will also receive royalties on worldwide net sales of any Novartis products incorporating its sensor-based technology.
• Trillium Therapeutics, Inc., a biopharmaceutical company developing innovative immune-based biologics, announced that it has entered into a definitive license agreement with Biogen Idec, Inc. (BIIB), granting the latter exclusive worldwide rights to one of Trillium’s development programs.  Under the terms of the agreement, Trillium will receive an upfront payment and is eligible to receive milestone payments based on achievements of specified clinical, regulatory and commercial accomplishments.  Trillium will also receive royalties on global product sales.  Biogen Idec will be solely responsible for clinical development, regulatory approvals, manufacturing and commercialization.
• MedGenesis Therapeutix Inc., a biopharmaceutical company developing and commercializing innovative treatments for patients with serious central nervous system [CNS] diseases, announced an agreement with Amgen, Inc. (AMGN) that provides MedGenesis with an exclusive, worldwide license for glial cell line-derived neurotrophic factor [GDNF] protein in CNS and non-CNS indications.  As part of the license agreement, Amgen now holds a small equity stake in MedGenesis.  In parallel, Biovail Corporation (BVF) and MedGenesis concluded an agreement to collaborate on the development of GDNF in Parkinson’s disease and potentially other CNS indications.  GDNF is a naturally-occurring growth factor capable of protecting and promoting the survival of dopamine producing nerve cells.
• AstraZeneca Plc (AZN) and CrystalGenomics announced a research collaboration to discover and develop a novel anti-infective for use as a potential antibacterial agent.  Under the terms of this agreement, Korea-based CrystalGenomics will receive research funding from AstraZeneca for two years.  CrystalGenomics will also be eligible to receive future milestones and royalty payments associated with development and commercialisation of a drug candidate.
• AnaptysBio, Inc., a privately-held therapeutic antibody platform and product company, announced it has signed an agreement with Roche (RHHBY) for the development of novel antibody therapeutics.  Under the terms of the agreement, AnaptysBio will be responsible for generating novel antibodies using its proprietary somatic hypermutation platform and Roche will receive a worldwide license to develop and commercialize antibodies optimized by AnaptysBio.  In addition to a signing fee paid by Roche, AnaptysBio will be eligible to receive milestone payments and royalties upon product sales.

The six transactions announced during the JP Morgan Healthcare Conference in 2010 with reported financial terms totaling $314 million pale in comparison to the ten deals reported at the meeting during 2009 worth more than $2.4 billion in aggregate value.  These included a $1.1 billion deal between ZymoGenetics, Inc. (ZGEN) and Bristol-Myers Squibb Company (BMY), a $500 million deal between Peptimmune, Inc. and Novartis AG, a $396 million deal between Micromet, Inc. (MITI) and Bayer AG (BAYZF.PK), and a $200 million deal between FORMA Therapeutics the Novartis Option Fund to develop inhibitors for an undisclosed protein-protein interaction target in the field of oncology, among others.

Financing

The quantity and aggregate dollar value of public and private financing transactions announced during the JP Morgan Healthcare Conference were essentially flat in 2010 compared with the prior year as reflected in the table below.

Outlook

At the start of 2009, we provided a positive outlook for biotechnology, citing the sector’s defensive characteristics, favorable technical aspects, and improving fundamentals, such as the number of new product approvals, products in clinical trials and the brisk pace of industry consolidation and licensing transactions.  The latter was quickly reinforced by M&A transactions with an aggregate value of $702 million and licensing & partnering deals worth more than $2.4 billion in aggregate value announced January 12-15, 2009, during the JP Morgan Healthcare Conference. 

While we believe that a positive outlook for 2010 is once again warranted, and the first two weeks of the year don’t necessary indicate a trend, hopefully the paucity of M&A activity coupled with the decline in both the quantity and value of licensing & partnering transactions announced during the JP Morgan Healthcare Conference in 2010 is simply the pause that refreshes and the action improves throughout the year.

What is GVHD? 

When a cancer patient with myeloma, lymphoma, or other blood-borne diseases does not respond to traditional pharmacological therapies, hematopoietic stem cell transplantation [HCT] is often used as a last line of defense.  HCT is the transplantation of blood stem cells derived from the bone marrow or peripheral blood to the patient.  There are two types of HCT:

• Autologous : stem cells come from patient’s own blood or bone marrow
• Allogeneic: stem cells come from another person

While HCT remains a risky procedure with many possible complications, technological advances have resulted in diminished transplant-related deaths.  As a result, the number of allogeneic HCTs performed continues to rise, with greater than 25,000 procedures currently performed annually and the number is expected to double within five years [ref 1].

One of the major complications associated with allogeneic HCTs is GVHD.  GVHD is an immunological disorder that affects many organ systems including the gastrointestinal [GI] tract, skin, liver, and lungs.  If it happens within 3 months, it is called acute GVHD.  If it happens after 3 months, it is called chronic GVHD and may take as long as 3 years to go away.

GVHD arises when donor immune cells attack defined proteins on the host cells resulting in an array of clinical features ranging from mild [grade 1] to very severe [grade 4].  Severe GVHD [grade 3] has poor prognosis, with 25% long-term survival and only 5% for very severe GVHD [ref 1].

Within the GI tract, GVHD usually presents as bleeding, diarrhea, vomiting, anorexia, and abdominal pain.  The clinical symptoms of GI GVHD are those of typical inflammatory mechanisms and thus can be summarized into three sequential steps: 1) activation of antigen-presenting cells, 2) immune cell proliferation, and 3) target tissue destruction.  

The primary pharmacological strategy to prevent GVHD is the use of cyclosporine and tacrolimus in combination with other immunosuppressants.  Despite these prophylactic therapies, GVHD still develops in 30%-80% of patients in the second month following HCT [ref 2].  Steroids, including prednisone, remain the gold standard therapy for GVHD treatment but only 25% to 41% of patients treated have complete GVHD remission [ref 3].  In addition, systemic treatment with prednisone or other steroids can lead to severe side effects such as opportunistic infections, electrolyte imbalances, and lymphoproliferative disease.

Currently, no therapies are approved by the United States Food and Drug Administration [FDA] for either prevention or treatment of GVHD [ref 4].  GVHD represents a growing problem due to an increasing number of HCT procedures and HCT survival with no change in the morbidity and mortality of this complication [ref 4].  As a result there is a great-unmet medical need to find therapies for this disease.

Past Failures

While several companies have brought new therapies into late-stage clinical development, no FDA approved treatments are currently available for the treatment or prevention of GVHD.  There are three primary reasons for this:

1. One of the difficulties in finding new GVHD therapies is due to a lack of understanding of the pathophysiology of the syndrome.  Many different triggers can cause immunological diseases and the best therapeutic target has not been determined.  However, the very complexity of GVHD affords the opportunity to treat it by attacking its many different levels.
2. The second reason for the high number of failures relates to the delicate balance between the harmful consequences of GVHD and the beneficial effects incurred when donor T cells attack malignant cells, a process referred to as the graft versus leukemia effect [GvL] and the underlying reason for performing HCT.  With the use of immunomodulatory agents to treat GVHD, consideration must be given to the need to control the immune response of GVHD without compromising the disease-fighting role of the donor immune cells.
3. Thirdly, there are inherent difficulties in conducting human clinical trials.  The difficulty of demonstrating clinical benefits from objective parameters, such as survival and morbidity, and the subjectivity of grading acute GVHD, emphasize the need for blinded assessments in clinical trials of GVHD treatment [ref 5]. 

Regardless of the specific cause, there have been many high-profile, late-stage clinical trial failures, several of which are summarized below in reverse chronological order:

Osiris Therapeutics, Inc. (OSIR)

In September 2009, Osiris Therapeutics announced preliminary results from its two Phase III trials evaluating Prochymal for the treatment of GVHD.  The active ingredient of Prochymal is adult mesenchymal stem cells [MSCs].  The cells are from normal healthy adult volunteer donors and are not derived from a fetus, embryo or animal.  Studies have shown that these cells are universally compatible.  Similar to Blood Type O, these MSCs may be used without tissue type matching for specific patients.  Prochymal is produced in a controlled setting and is tested for possible infectious agents [such as viruses, bacteria, etc.] before it is given by infusion into a vein.

While Prochymal showed improvements in response rates for GI GVHD, neither trial achieved its primary endpoint.  There was no statistical difference between Prochymal and placebo for the steroid-refractory (35% vs. 30%, n=260) or first-line GVHD trials (45% vs. 46%, n=192).  However, in patients with steroid-refractory liver GVHD, treatment with Prochymal significantly improved response (76% vs. 47%, p=0.026, n=61) and durable complete response (29% vs. 5%, p=0.046). Osiris plans to meet with the FDA to evaluate the trial and discuss the next steps for moving forward with Prochymal.

SangStat Medical Corporation (SANG) and Abgenix (ABGX)

In February 2003, SangStat [subsequently acquired by Genzyme Corporation (GENZ)] and Abgenix [subsequently acquired by Amgen, Inc. (AMGN)] presented data from their Phase II/III study for evaluating ABX-CBL in patients with steroid-resistant GVHD.  The data presented showed that patients treated with ABX-CBL, an anti-CD147 monoclonal antibody, were similar to the control arm [antithymocyte globulin].  The primary endpoint of this study was to demonstrate superior survival with ABX-CBL, thus the primary endpoint was not met.  Further development of ABX-CBL for GVHD is not expected.

Roche (OTCQX: RHHBY) and Protein Design Labs, Inc. (PDLI) 

In 1995, Roche and Protein Design Labs presented the results of a study using Zenapax™ [daclizumab], a humanized monoclonal antibody against the interleukin-2 [IL-2] receptor, for the prevention of GVHD following bone marrow transplantation. The 102 patient study was halted after a planned interim analysis showed a significantly worse 100-day survival in the group receiving corticosteroids plus daclizumab (77% vs. 94%; p=0.02).  Overall survival at 1 year was also inferior in the combination arm (29% vs. 60%; p=0.002).  Both relapse- and GVHD-related mortality contributed to the increased mortality in the combination group.  Roche concluded that Zenapax is not effective in reducing the incidence of GVHD in the population of patients included in this study.

XOMA Ltd. (XOMA)

In December 1994, results of a Phase III trial of Xoma’s CD5 Plus™, a CD5-specific immunotoxin, for the treatment of GVHD were presented at the annual meeting of the American Society of Hematology.  A total of 243 patients were included in the trial, all of whom developed acute GVHD after allogeneic bone marrow transplantation. The trial compared CD5 Plus and a standard steroidal immunosuppressant therapy [methylprednisolone] versus placebo and steroids as initial therapy. The primary endpoint was defined as no evidence of acute GVHD at day 43 post starting treatment.

While the percentage of patients with no evidence of GVHD was higher in the CD5 Plus group than in the placebo group during the entire 43-day period of observation, at 6 weeks the difference was not statistically significant [44% of patients assigned to the CD5 group had complete response as compared with 38% in the placebo group, p=0 .36].  Xoma discontinued development of CD5 Plus.

New Opportunities

Despite the challenges in developing GVHD therapies, several companies are continuing with both preclinical and clinical programs.  The approaches range from novel, locally acting steroids [lower risk] to more complex immunomodulatory agents and cell cycle regulators [higher risk].  Several companies with promising programs in the GVHD space along with their technology and clinical development status are as follows:

Novel, Locally Acting Steroids

Soligenix, Inc. (SNGX) is developing orBec® [oral beclomethasone dipropionate] for the treatment of acute GI GVHD.  Beclomethasone [BDP] is a corticosteroid with potent topical activity used for inflammatory disorders affecting mucosal surfaces, such as the GI tract.  BDP’s mechanism of action is similar to other corticosteroids acting as an inhibitor of inflammatory cytokine production of immune cells.  One of the clear advantages of BDP versus other steroids is that oral BDP does not enter into the circulation thus avoiding many of the side effects associated with systemic steroid uses.  Pharmacokinetic studies have shown that BDP is metabolized in the intestinal mucosa and only the inactive metabolite is found in the circulation.  Additionally, the safety profile of BDP is well studied as it is approved by the FDA for three indications:

• Becloforte®: inhalant marketed by GlaxoSmithKline plc (GSK) and used to treat asthma
• Beconase®: nasal spray marketed by GlaxoSmithKline for rhinitis
• Propaderm®: topical cream for psoriasis

Formulated for oral administration as a single product, orBec is a single product consisting of two separate pills.  One tablet is intended to release BDP in the proximal portions of the GI tract, and the other tablet is intended to release BDP in the distal portions of the GI tract.  This novel delivery system ensures that BDP is delivered to the entire GI tract.

Soligenix recently completed a 129-patient randomized, double blind, placebo-controlled, multicenter trial Phase III trial for orBec.  While the primary endpoint of this trial, time-to-treatment failure through day 50, did not reach statistical significance [p=0.1177], orBec did meet statistical significance for all of the secondary endpoints, such as the proportion of patients free of GVHD at Day 50 (p=0.05) and Day 80 (p=0.005) and the median time-to-treatment failure through Day 80 (p=0.0226).

Importantly, among all of the late-stage clinical trials for GVHD listed in Table 1, orBec is the only product to demonstrate a reduction in mortality.  In the Phase III trial, there was a 66% reduction in mortality among patients randomized to orBec at 200 days post-transplant with only 5 patient [8%] deaths in the orBec group compared to 16 patient [24%] deaths in the placebo group (p=0.0139).  At one year post-randomization in the Phase III trial, 18 patients [29%] in the orBec group and 28 patients [42%] in the placebo group died within one year of randomization [46% reduction in mortality, hazard ratio 0.54, 95% CI: 0.30, 0.99, p=0.04, stratified log-rank test]. 

Soligenix received a special protocol assessment [SPA] for a confirmatory, pivotal Phase III clinical trial cleared by the FDA.  The European Medicines Agency [EMEA] also agreed that should the new confirmatory Phase III study produce positive results, the data would be sufficient to support a marketing authorization approval in all 27 European Union [EU] member states.  Importantly, the primary endpoint for this study, treatment failure rate at day 80, was statistically significant in the prior Phase III trial [p=0.005].  The trial is enrolling patients and Soligenix has partnered with Sigma-Tau Pharmaceuticals, Inc. for commercialization of orBec.

Immunomodulatory Agents

In July 2009, results were published from a randomized, 4-arm, Phase II trial of 180 patients designed to identify the most promising agent(s) for initial therapy for acute GVHD [ref 3].  Patients were randomized to receive methylprednisolone 2 mg/kg per day plus etanercept [Enbrel® by Amgen, Inc. and Wyeth Pharmaceuticals], mycophenolate mofetil [MMF, CellCept® by Roche], denileukin diftitox [denileukin, Ontak® by Eisai Co., Ltd.], or pentostatin [Nipent® by Hospira, Inc.].  Day 28 complete response rates were etanercept 26%, MMF 60%, denileukin 53%, and pentostatin 38%.  Corresponding 9-month overall survival was 47%, 64%, 49%, and 47%, respectively.  Cumulative incidences of severe infections were as follows: etanercept 48%, MMF 44%, denileukin 62%, and pentostatin 57%.  Efficacy and toxicity data suggest the use of Roche’s MMF plus corticosteroids is the most promising regimen to compare against corticosteroids alone in a definitive Phase III trial.  The Phase II study is registered at ClinicalTrials.gov [identifier NCT00224874].

Cell Cycle Regulators

GVHD is initiated when host antigen-presenting cells are detected by donor T-cells leading a cascade of cellular signaling events resulting in the expansion of donor immune cells and release of cytokines and chemokines, resulting in physiological damage to the GI tract and presentation of GVHD clinical symptoms. 

Cyclacel Pharmaceuticals, Inc. (CYCC) is developing seliciclib [CYC202 or R- roscovitine] for the treatment of acute GVHD.  Seliciclib is an inhibitor of cyclin-dependent kinases [CDKs], such as CDK2, CDK7 and CDK9.  Although seliciclib is in preclinical development for GVHD, the product is also in Phase II trials for nasopharyngeal cancer and non-small cell lung cancer.

CDKs have been shown to be central kinases involved in the regulation and progression of the cell cycle.  Inhibition of CDK2 leads to cell cycle arrest and apoptosis and CDK7 and CDK9 to suppression of transcription in aberrantly proliferating cells.  Investigators from Harvard Medical School have recently published in vitro and in vivo evidence that CDK inhibition by seliciclib suppressed activation and expression of T cells and resulted in protection from acute GVHD [ref 6].  Seliciclib’s mechanism had three primary consequences in the context of GvHD:

1. Inhibition of CDKs resulting in blocking the cell cycle
2. Inhibition of RNA polymerase 2 resulting in apoptosis
3. Prevention of TNF alpha dependent NFkB activation, a pathway shown to be activated in GVHD

Together, seliciclib may be able to specifically target the allo-reactive T cells preventing the progression of GVHD without targeting the immune cells needed for GvL or other pathogens.

Conclusion

A number of novel agents have been investigated to target various aspects in GVHD.  The majority of previous clinical trial setbacks have been immunomodulatory agents, which may favor lower-risk, steroid-sparing approaches in the short-term given the complexity of GVHD.  Ultimately, there appears to be potential synergies between different therapies, as they all possess different mechanisms and targets.  Future results from an ongoing pivotal trial and additional clinical results could provide optimism for both patients and investors in the GVHD space.

Table 1: Late-Stage, Completed GVHD Trials

References:

1. Lancet 2009; 373: 1550–61
2. Expert Opin Investig Drugs. 2008 Sep;17(9):1389-401
3. Blood. 2009 Jul 16;114(3):511-7
4. Blood. 2005 Jun 1;105(11):4200-6
5. Biol Blood Marrow Transplant. 2009 Jul;15(7):777-84.
6. Cell Cycle 8:11, 1794-1802; 1 June 2009

Early this morning, Celgene Corporation (CELG) announced the acquisition of privately-held Gloucester Pharmaceuticals for $340 million in cash plus another $300 million in future U.S. and international regulatory milestone payments.  Gloucester’s Istodax® (romidepsin) was approved in November 2009, by the U.S. Food and Drug Administration [FDA] for the treatment of cutaneous T-cell lymphoma [CTCL] and is being developed for other hematological malignancies, including peripheral T-cell lymphoma [PTCL].

While many potential acquirers may have been sitting on the sidelines watching the market valuations of cash-poor companies continue to decline throughout the year, those depressed share prices may not last much longer.  Improving capital markets for small-cap life sciences companies, evidenced in part by this month’s $48 million follow-on financing by ZIOPHARM Oncology, Inc. (ZIOP), could accelerate merger and acquisition activity in the sector as larger companies race to fill anticipated patent expirations and gaps in their product pipelines.  Indeed, a favorable climate for merger and acquisition activity was one of the main tenets of our positive perspectives for biotechnology in 2009.

Following Celgene’s acquisition of Gloucester, we revisited the baker’s dozen of public biotechnology companies announcing upcoming clinical data presentations at ASH [as of November 27, 2009] from our recent article and identified three small-cap [eg, market capitalization less than $1 billion] biotechnology companies with unpartnered, late-stage [eg, marketed or entering pivotal trials] hematological malignancy programs:

• Allos Therapeutics, Inc. (ALTH): The company is commercializing Folotyn™ (pralatrexate injection), an antimetabolite approved for the treatment of patients with relapsed or refractory PTCL.  While Allos has retained exclusive worldwide rights to Folotyn, which became available in the United States in October 2009, potential competition from Istodax by Celgene/Gloucester may be a concern as a supplemental NDA for PTCL is expected by year-end 2010.  Further, the company was the subject of an article in the December 4, 2009, New York Times questioning its pricing for Folotyn.
• Seattle Genetics, Inc. (SGEN): In February 2009, the company initiated a pivotal trial of its brentuximab vedotin product candidate in patients with relapsed or refractory Hodgkin lymphoma under a Special Protocol Assessment with the FDA.  Seattle Genetics expects to submit both a New Drug Application [NDA] with the FDA under the accelerated approval regulations and a Marketing Authorization Application with the European Medicines Agency for conditional marketing authorization in the first half of 2011.  The company has retained exclusive worldwide rights to brentuximab vedotin.
• Cyclacel Pharmaceuticals, Inc. (CYCC): At the ASH meeting, Cyclacel reported promising 1-year survival data from a Phase 2 randomized trial of its oral sapacitabine capsules in elderly patients with acute myeloid leukemia [AML] and separately interim response data in myelodysplastic syndromes [MDS].  The company is planning to start a pivotal trial with sapacitabine in 2010 and has retained exclusive worldwide rights with the exception of Japan where Daiichi-Sankyo has a right of first refusal to market the drug under terms to be negotiated.

In this regard, Celgene Corporation (CELG) recently announced that data from more than 200 clinical trials involving the company’s products will be presented at the ASH annual meeting.  After reaching a 52-week low of $36.90 in April 2009, shares of Celgene have rebounded nearly 50% to close at $54.97.  As a result, investors may gravitate to other biotechnology companies specializing in the area of hematology to uncover similar investment opportunities.

Accordingly, we recently reviewed press releases from a baker’s dozen of public biotechnology companies also announcing upcoming clinical data presentations at ASH [as of November 27, 2009].  Further, to determine which topics are likely to generate significant visibility and investor interest, we tallied the number of abstracts accepted for each company, identified the product development stage(s), and consolidated the therapeutic classes into the following four general categories:

1. Kinase inhibitors
2. Biologic agents [monoclonal antibodies and small modular immunopharmaceuticals]
3. Chemotherapeutics [antimetabolites, nucleoside analogues topoisomerase inhibitors, and HDAC inhibitors]
4. Others [proteasome inhibitors and anticoagulants]

 See Table 1 below for the results from the 32 abstracts referenced in the press releases.

 Table 1. Baker’s dozen of public biotechnology companies issuing press releases regarding clinical data presentations at ASH

Note: One abstract is listed under both Keryx Biopharmaceuticals and AEterna Zentaris, as perifosine rights have been licensed to Keryx Biopharmaceuticals for North America, while AEterna Zentaris has the rest of world rights.  Two abstracts are listed under both Trubion Pharmaceuticals, Inc. and Facet Biotech Corporation, as the companies entered into a worldwide development and commercialization agreement for TRU-016.

Kinase Inhibitors

Inhibitors of intracellular kinases have the potential to be synergistic with several classes of chemotherapeutic and immunotherapeutic agents.  For example, different cancers have mutations on a few key kinases [such as PI3K], many of which lead to increased cellular growth, proliferation, angiogenesis, and survival.  In addition, many kinases have elevated expression levels or increased activity with several cancers.  Also, while antibodies may target one specific receptor, often multiple receptors are overactive in cancer cells; however, the different receptor signals may converge upon a central nodal signaling point making pharmacological intervention possible. 

Intracellular kinase inhibitors vary not only by their target [and isoform selectivity] but also by their inhibition mechanism.  For example, some small molecule inhibitors are ATP analogs, catalytic domain inhibitors, non-catalytic domain inhibitors, or target ligand inhibitors.  Some of the most studied intracellular kinases include PI3K, mTOR, AKT, SRC, JNK, and others.

One of the major drug development problems to date is that inhibition of one pathway leads to upregulation of a parallel signaling pathway.  It will be important for researchers to decipher the roles of redundant parallel pathways and feedback loops. Together, inhibition of the necessary intracellular signals needed for a cell to respond to external growth and survival factors have the potential to prevent further cancer growth. 

Due to significant interest in PI3K inhibitors, such as Keryx Biopharmaceuticals’ perifosine, we have also listed two private companies presenting Phase I clinical data at ASH.

Table 2. Kinase Inhibitor Presentations

Biologic Agents

Therapeutic applications of monoclonal antibodies [MAbs] are the most widely used form of immunotherapy for cancer at this time.  Examples of MAb mechanisms include prevention of ligand-receptor interaction, antibody dependent cellular cytotoxicity, complement mediated cytotoxicity, and immune modulation.  Most MAbs target cellular receptors that are overexpressed or specific to certain cancers.  New technology in MAbs has allowed for improved conjugations and increased penetration.

In view of significant interest in the area of MAbs, we have also included a private company presenting preclinical data demonstrating proof-of-concept at ASH with an IND planned for Q1 2010.

Table 3. Biologic Agent Presentations

Chemotherapeutics

Antimetabolites have well established anti-cancer profiles with actions on intermediary metabolism of proliferating cells.  The mechanism of action of antimetabolites is through the inhibition of nucleotide and nucleic acid synthesis.  Many of these drugs have delayed toxicity and are subject to drug resistance.  Examples of approved therapies include methotrexate, 5-FU, and more recently Allos Therapeutics’ Folotyn™ [pralatrexate injection]. 

Nucleoside analogues are similar in mechanism to alkylating agents.  Many nucleoside analogues kill cells by binding to DNA and forming strand breaks leading to an inhibition of DNA synthesis and function.  Nucleoside analogues are associated with nephrotoxicity but have shown to be synergistic with other therapies such as vinblastine.  Examples of approved nucleoside analogues include cisplatin and carboplatin.   In terms of development candidates, Cyclacel recently reported topline survival data from a Phase II study of its oral nucleoside analog, sapacitabine, in elderly patients aged 70 or older with either newly diagnosed acute myeloid leukemia [AML] or AML in first relapse.  The study was a three-arm, randomized trial evaluating three dosing schedules of sapacitabine.  The primary endpoint of one-year survival was approximately 30% in two out of the three schedules tested and further details of the study will be presented at ASH.

Histone deacetylase enzymes [HDACs] are a group of proteins that deacetylate lysine residues on core histones resulting in chromatin condensation and gene repression.  In addition, HDACs have been shown to inhibit transcription factors and interact with other proteins including p53 and c-myc.  There are three classes of HDACs each with unique domains and cellular expression profiles [and cancer expression profiles].  Thus, HDACs have a diverse and complex role in cellular activity.  HDAC inhibitors have shown to induce apoptosis, while it is not clear if HDAC specific or pan-HDAC inhibitors, such as Pharmacyclics’ PCI-24781, will have the best clinical outcome.   An example of an FDA approved HDAC inhibitor is Merck & Co.’s (MRK) Zolinza® [vorinostat].

Table 3. Chemotherapeutic Presentations

Others

In 2003, Velcade® [bortezomib] by Millennium Pharmaceuticals, Inc., a wholly-owned subsidiary of Takeda Pharmaceutical Company Limited, became the first proteasome inhibitor to be approved for use in the U.S.  Bortezomib disrupts normal protein homeostasis by targeting the proteasome, the final enzyme in the proteolysis cycle that is critical for normal protein turnover and homeostasis.  Proteasome inhibitors are linked with decreased NF-kappaB [NFkB] activity, which has been shown to be a central transcription factor involved with this disease.  In addition to NFkB, proteasome inhibition has other antitumor activity such as p53 stabilization.  Because the proteasome has been validated as a target for myeloma, other drugs, such as Onyx Pharmaceuticals’ carfilzomib, are in development with novel features such as decreased toxicity and increased potency.

In August 2009, Gentium S.p.A. announced top-line results from a Phase III trial designed to evaluate the safety and efficacy of 25 mg/kg/day of defibrotide, a deoxyribonucleic acid derivative derived from cow lung or porcine mucosa, for the treatment of severe veno-occlusive disease in hematopoietic stem cell transplant patients.  The results did not reach the protocol-specified levels of significance for the primary and secondary endpoints at 100 days.  The Company plans to present full results from the trial at ASH.

Table 4. Other Presentations

Summary

Stocks to watch at ASH by conference/presentation date:

Saturday, December 5, 2009: IMGN, FACT, CYCC, SNSS, TRBN, KERX, AEZS, ALTH

Sunday, December 6, 2009: IMGN, PCYC, SGEN

Monday, December 7, 2009: FACT, IMGN, ARIA*, TRBN, SNSS, GENT, PCYC, ONXX*, ALTH, SGEN

Tuesday, December 8, 2009: ALTH

* Company has announced plans to host an investor teleconference in connection with the ASH presentation(s)