Medarex Says Forget Pfizer, Its Own Melanoma Study Continues (MEDX, PFE, BMY)

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Medarex, Inc. (NASDAQ: MEDX) wants to clarify a few issues regarding the study halt from Pfizer (NYSE: PFE) this week on advanced melanoma.  The company says that there are key differences between Pfizer’s discontinuing its Phase 3 clinical trial of front-line treatment of tremelimumab compared to chemotherapy in patients with advanced melanoma.

Pfizer’s tremelimumab and Medarex’s ipilimumab do have a similar mechanism and have been considered by some as similar molecules, and it is natural to attempt to draw parallels between the two molecules.

But Medarex wants to clarify some issues.  The two antibodies are different molecules, and results from one antibody program may not be indicative of the same results from another program.  While it previously reported that results from the Phase 2 study did not meet the primary endpoint, the three studies in its Phase 2 program were suggestive of ipilimumab’s potential for clinical anti-tumor activity and are under discussion with regulatory agencies.  Medarex’s ongoing ipilimumab Phase 3 program for front-line treatment of advanced melanoma is different in design from the Pfizer trial, and it is too early to draw any clinical conclusions from the Pfizer announcement and a recent review of its ongoing Phase 3 trial by the Data Monitoring Committee indicated that the Medarex trial should continue.

Lastly, Medarex noted that Bristol-Myers Squibb Company (NYSE: BMY) is its partner for ipilimumab and its studies are continuing to move forward; and prior guidance is unchanged and regulatory discussions are pending.

Medarex shares were up about 2% shortly after it issued this clarification statement.  Unfortunately shares are back to down marginally by 0.25% at $7.61 right before the open.  As we have noted, this is the largest potential candidate it has right now.  But this company also has many partnerships and an extensive pipeline of potential drug candidates, and it continues to win milestones on other studies and candidates.

Jon C. Ogg
April 3, 2008