- AbbVie hit a setback in the development of its experimental cancer drug veliparib, as results from a mid-stage trial presented Wednesday showed the poly(ADP-ribose) polymerase (PARP) inhibitor missed its primary and secondary endpoints in patients with BRCA-mutant breast cancer
- Treatment with veliparib plus chemotherapy did lead to a small improvement in progression-free survival (PFS) versus placebo plus chemotherapy, but the result was not statistically significant. Change in overall survival (OS) was also not statistically significant.
- AbbVie is currently studying veliparib in a much-larger, pivotal Phase 3 trial, which is expected to complete in March 2018, according to clinicaltrials.gov.
Note: This post has been updated to include comments from an AbbVie representative on the results of the trial.
PARP inhibitors have drawn a lot of attention recently.
Massachusetts-based biotech Tesaro, Inc. has soared this year after showing its cancer drug niraparib extended PFS by 16 months in patients with BRCA-mutated ovarian cancer.
Elsewhere, AstraZeneca has seen similarly promising data from its own PARP inhibitor Lynparza in that same indication. And then there was Pfizer-owned Medivation, which made much of the prospects for its talazoparib during the bidding war to acquire the San Francisco-based biotech earlier this year.
Unfortunately for AbbVie, the Phase 2 study of veliparib did not join the ranks of PARP clinical successes.
Nearly 300 patients were randomized to three study arms: veliparib plus carboplatin and paclitaxel, placebo plus carboplatin and paclitaxel and veliparib plus temozolomide. (Results presented Wednesday only highlighted the data from the first two arms.)
Adding veliparib to chemotherapy did extend PFS, but only by a marginal 1.8 months compared to the placebo arm— a statistically insignificant result. Median overall survival trended in favor of the veliparib arm but at 28.3 months versus 25.9 months for the placebo arm, the results were not statistically significant.
Heather Han, a researcher with the Moffitt Cancer Center who was involved in the study, believed the study size to be too small to detect "nondramatic improvements" in PFS. According to Han, the ongoing Phase 3 study is sufficiently powered to pick up statistical significance.
AbbVie had designed the Phase 2 study as a "signal generation trial" to inform the necessary size needed for the Phase 3 study.
"The positive trends in OS, PFS and ORR [objective response rate] were of sufficient magnitude to warrant continuation of the phase 3 trial," said Vince Giranda, project director at AbbVie Oncology Development.
In a good sign for AbbVie's ongoing clinical work on the drug, the addition of veliparib to chemotherapy did not significantly increase the rate of adverse events.
Although Phase 2 results certainly don't excite, the defining judgment on veliparib will be determined by what happens in the pivotal trial.