PRINCETON, N.J., April 3, 2008 Medarex, Inc.(Nasdaq: MEDX) today issued the following statement in response to theannouncement by Pfizer Inc that it was discontinuing its Phase 3 clinicaltrial of front-line treatment with Pfizer's single-agent anti-CTLA-4 antibody(tremelimumab) compared to chemotherapy in patients with advanced melanoma.Dr. Geoffrey M. Nichol, M.B.Ch.B., Senior Vice President, Product Developmentof Medarex, stated:
"While Pfizer's tremelimumab and Medarex's ipilimumab have a similarmechanism of action and have been considered by some as similar molecules, itis natural to attempt to draw parallels between the two molecules. However, wefeel we need to make certain clarifications. First, the two antibodies aredifferent molecules, and results from one antibody program may not beindicative of results from another program. The molecules are of different IgGantibody subclasses, administered at different doses and dosing schedules, andwith different pharmacokinetic parameters.
Second, while, as previously reported, the results from the Phase 2 studyunder special protocol assessment did not meet the primary endpoint, the threestudies in our Phase 2 program were suggestive of ipilimumab's potential forclinical anti-tumor activity based on the totality of the data and are underdiscussion with regulatory agencies.
Third, Medarex's ongoing ipilimumab Phase 3 program (study 024) for front-line treatment of advanced melanoma is different in design from the Pfizertrial, and at this time, it is too early to draw any clinical conclusions fromthe Pfizer announcement. In addition, a recent review of our ongoing 024 Phase3 trial by the Data Monitoring Committee (DMC) indicated that our trial shouldcontinue.
Finally, we and our partner, Bristol-Myers Squibb Company, continue tomove firmly forward. Our previously-stated guidance remains unchanged andregulatory discussions are pending."
About the Chemotherapy Combination Registrational Trial
Study 024 is a randomized, blinded registrational Phase 3 study designedto evaluate the effect of dacarbazine in combination with 10mg/kg ipilimumabor placebo on progression-free survival and overall survival in 500 patientswith previously untreated metastatic melanoma (front-line). Ipilimumab isadministered at 10 mg/kg once every three weeks for up to four doses.Subsequently, eligible patients who have not experienced disease progressionat week 24 will continue in a maintenance phase where a single dose ofipilimumab or placebo will be administered once every 12 weeks until diseaseprogression. All efficacy analyses, except for overall survival and survivalrate at one year, will be conducted when at least 416 events for progression-free survival have been observed in the study and all patients have beenfollowed for at least 12 weeks.
In June 2006, the 024 registrational Phase 3 trial was reviewed by theU.S. Food and Drug Administration (FDA) under a Special Protocol Assessment(SPA) concerning the suitability of the trial design to support regulatoryapproval. In December 2006, the FDA granted Fast Track status to this programwhich provides for expedited regulatory review for new drugs that demonstratethe potential to address unmet medical needs for the treatment of serious orlife-threatening conditions. Trial enrollment was completed in the first-quarter of 2008.
Ipilimumab is a fully human antibody that binds to CTLA-4 (cytotoxic Tlymphocyte-associated antigen 4), a molecule on T-cells that plays a criticalrole in regulating natural immune responses. The absence or presence of CTLA-4 can augment or suppress the immune system's T-cell response in fightingdisease. Ipilimumab is designed to block the activity of CTLA-4, therebysustaining an active immune response in its attack on cancer cells.
Comprehensive Clinical Trial Program for Ip