Merck and Pfizer are pulling the plug on a late-stage trial assessing the potential of their PD-L1 antibody avelumab in ovarian cancer front-line maintenance setting.

The Phase III JAVELIN Ovarian PARP 100 study was evaluating the efficacy and safety of avelumab in combination with chemotherapy followed by maintenance therapy of avelumab in combination with PARP inhibitor talazoparib, versus an active comparator in treatment-naïve patients with locally advanced or metastatic ovarian cancer (Stage III or Stage IV).

The decision to stop the trial is based on “several emerging factors since the trial’s initiation”, including previously announced interim data from the JAVELIN Ovarian 100 study, which was terminated earlier this year after a planned interim analysis showed that the avelumab would not achieve superiority in the pre-specified primary endpoint of progression-free survival (PFS).

The degree of benefit observed with avelumab in frontline ovarian cancer in that study does not support continuation of the JAVELIN Ovarian PARP 100 trial in an unselected patient population and emphasises the need to better understand the role of immunotherapy in ovarian cancer.

The companies also highlighted that additional factors, such as the “rapidly changing treatment landscape” and the approval of a PARP inhibitor in the frontline maintenance setting, also played a role, and stressed that the decision to discontinue the JAVELIN Ovarian PARP 100 trial “was not made for safety reasons”.

Merck and Pfizer also noted that the decision to discontinue the trial does not impact the currently approved indications for avelumab or the remainder of the ongoing JAVELIN clinical development programme.