Dimebon Disappoints Again

Medivation, Inc. (MDVN - Analyst Report) suffered another development setback recently with its phase III candidate, dimebon, failing to achieve the primary endpoints in a phase III study for Huntington disease.

Dimebon, for which Medivation has a  global collaboration with Pfizer, Inc. (PFE - Analyst Report), failed to achieve statistical significance in either of its co-primary endpoints. Based on the results, Medivation and Pfizer have decided to discontinue development of dimebon for Huntington disease. The companies will no longer continue with an open-label extension study that was being conducted with the candidate.

However, Medivation and Pfizer intend to continue with a phase III trial (CONCERT) as well as an open-label extension evaluating dimebon for mild-to-moderate Alzheimer's disease. Top-line data from the CONCERT study will be available in the first half of 2012. Medivation estimates that it will incur an additional cost of less than $5 million to complete the CONCERT study.

We have low expectations from this study. We note that dimebon failed to achieve both its primary and secondary endpoints in a previous phase III study (CONNECTION) for moderate-to-severe Alzheimer’s disease.

With dimebon failing in two phase III studies, we now expect investor focus to shift to Medivation’s prostate cancer candidate, MDV3100, which is being developed in collaboration with Astellas Pharma.

Medivation said that its phase III AFFIRM trial in post chemotherapy patients is fully enrolled, with top-line data expected in 2012. However, data could be available in 2011 itself if Medivation and Astellas decide to conduct an interim analysis. Meanwhile, patient enrolment for the phase III PREVAIL study in chemotherapy naïve patients is ongoing.

A head-to-head phase II study (TERRAIN) between MDV3100 and AstraZeneca’s (AZN - Analyst Report) Casodex (bicalutamide) is also being conducted. Finally, Medivation and Astellas remain on track to commence another phase II study in hormone-naïve patients in the second quarter.

Neutral on Medivation

We currently have a Neutral recommendation on Medivation, supported by a Zacks #3 Rank (short-term Hold rating). Given the disappointing track record of dimebon, we are concerned about partner Pfizer’s commitment towards the collaboration. With dimebon failing in two phase III studies, we expect investor focus to shift to the development of MDV3100.

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