Medarex says ipilimumab program moves forward

Following the the announcement by global drug giant Pfizer that it was discontinuing its Phase III clinical trial of front-line treatment with its single-agent anti-CTLA-4 antibody, tremelimumab, compared to chemotherapy in patients with advanced melanoma (Marketletter April 7) Medarex said that its ipilimumab - partnered with Bristol-Myers Squibb - will continue in development .

Geoffrey Nichol, senior vice president, product development of Medarex, stated: "while Pfizer's tremelimumab and Medarex' ipilimumab have a similar mechanism of action and have been considered by some as similar molecules, it is natural to attempt to draw parallels between the two molecules. However, we feel we need to make certain clarifications. First, the two antibodies are different molecules, and results from one antibody program may not be indicative of results from another program. The molecules are of different IgG antibody subclasses, administered at different doses and dosing schedules, and with different pharmacokinetic parameters."

Second, he said "while, as previously reported, the results from the Phase II study under special protocol assessment did not meet the primary endpoint, the three studies in our Phase II program were suggestive of ipilimumab's potential for clinical anti-tumor activity based on the totality of the data and are under discussion with regulatory agencies. Third, Medarex' ongoing ipilimumab Phase III program (study 024) for front-line treatment of advanced melanoma is different in design from the Pfizer trial and, at this time, it is too early to draw any clinical conclusions from the Pfizer announcement. In addition, a recent review of our ongoing 024 Phase III trial by the Data Monitoring Committee (DMC) indicated that our trial should continue."