AltaRex Corp., just days after it said it received both positive and nonsignificant results from its combined U.S. and Canadian Phase IIb trial in metastatic late-stage ovarian cancer, said Thursday a further analysis of those mixed results now show both affirmative and statistically significant results overall.
AltaRex’s stock (TSE:AXO) took the news of the conflicting studies hard last Friday, falling 66 percent, or C$1.65 (US$1.04), ending the day at C83 cents. Following the release of the new analysis Thursday, its stock climbed C62 cents, or 88.6 percent, closing at C$1.32.
The Phase IIb trial compared time to disease relapse, or TTR, of OvaRex monotherapy vs. placebo following surgery and chemotherapy. On Jan. 25, AltaRex, of Waltham, Mass., released this data: The U.S. arm of the trial showed median TTR for OvaRex to be statistically significant (15.5 months vs. 8.5 months for placebo, with p=.05) but the Canadian trial showed nonsignificant TTR results (8.2 months for OvaRex vs. 10.3 months for placebo). (See BioWorld Today, Jan. 28, 2001.)
After “further analysis of the disparity,” the company said, and excluding patients with prognostic factors for early relapse, as well as patients who are platinum insensitive, AltaRex now has a favorable outcome for the trial. In the new patient population analysis, the median time to relapse was 20.7 months for the 71 patients who took OvaRex vs. 13.5 months for the 77 receiving placebo. Also, AltaRex said when considering tumor antigen levels at initiation of treatment, the TTR figures shift to 20.7 months for 31 patients taking OvaRex vs. 10.2 months for the 33 on placebo, and also they become statistically significant (p=0.0174).
Additionally, an analysis of relapse-free survival, at 12 months from initiating treatment, for the population with available tumor antigen also gave statistically significant results 61 percent of OvaRex patients reached that level vs. 27 percent for placebo (p=0.011).
AltaRex’s president and CEO said, in a prepared statement that the company will follow through on an analysis of the Phase IIb trial as both a separate and a combined study. Also, he said he believes the results “warrant filing for approval, particularly as we have two additional trials ongoing.”