Threshold Pharmaceuticals, Inc. recently announced an amendment in the protocol for its pivotal phase III study of TH-302. The company said that the amendments have been accepted by the US Food and Drug Administration (FDA) under the existing Special Protocol Agreement (SPA). The phase III study will compare TH-302 in combination with Doxil to Doxil alone for treating patients with advanced soft tissue sarcoma (STS).
As per The American Cancer Society, around 11,410 new patients will be affected by soft tissue sarcoma in 2013.
The two changes made to the protocol include trial expansion to 620 patients (from 450) and the elimination of an interim futility analysis of progression-free survival (PFS).
The enlarged sample size will strengthen the study’s ability to find a clinically meaningful effect of TH-302 with statistically significant data. An interim futility analysis will no longer serve its original purpose as the study would have been through its enrollment phase by the time the analysis would be completed.
An Independent Data Monitoring Committee (IDMC) will monitor the safety of patients in this study. The IDMC will conduct an interim analysis for survival most likely in the first half of 2014, after 235 events are reached. The study will be terminated early if the IDMC finds pre-specified statistical results in its interim analysis. Otherwise, the study will continue until the final analysis, when 434 events would be completed. In that case, Threshold Pharma will come out with top-line results in the first half of 2015.
Threshold Pharma has a partnership with Merck KGaA for TH-302. TH-302 is in another phase III study that is evaluating the efficacy and safety of TH-302 plus Eli Lilly and Company’s (LLY - Analyst Report) Gemzar in patients with advanced pancreatic cancer.
The successful development of TH-302 will be a major milestone for Threshold Pharma, which currently does not have any marketed product in its portfolio. Threshold Pharma carries a Zacks Rank #4 (Sell). Right now, Biogen Idec Inc. (BIIB - Analyst Report) looks more attractive with a ZacksRank #1 (Strong Buy).