Merck and Pfizer’s Bavencio (avelumab) has fallen short in the Phase III JAVELIN Gastric 100 study, evaluating the antibody in unresectable, locally advanced or metastatic HER2-negative gastric or gastroesophageal junction (GEJ) cancer.

The topline results showed that the drug did not meet the primary endpoints of superior overall survival compared with standard of care, in either the overall intent-to-treat population or the PD-L1–positive population, despite the study showing clinical activity.

The news is disappointing for the patient population, as advanced gastric cancer – a hard to treat tumour type – is an area of high unmet need, "and to date no immune checkpoint inhibitor has demonstrated superiority to the current standard of care with chemotherapy,” said Professor Dr Markus Möhler, head of GI Oncology, Johannes-Gutenberg University, and coordinating investigator.

“As we have yet to define the ideal strategy for incorporating immunotherapy in the continuum of care, the results of JAVELIN Gastric 100 will provide essential information in advancing our understanding and potential treatment options of this challenging disease,” he added.

The Phase III, multicenter, randomised, open-label trial enrolled a total of 805 patients to receive induction (initial) chemotherapy with oxaliplatin and either 5-fluorouracil (5-FU) or capecitabine for 12 weeks.

Of these, 499 patients whose disease had not progressed at the end of the 12 weeks of chemotherapy treatment were randomly assigned to receive either Bavencio as a maintenance treatment or continuation of the same chemotherapy regimen until disease progression.

Globally, gastric cancer is the third most common cause of cancer death. The standard first-line option for patients with HER2-negative disease is chemotherapy, yet patients with advanced disease can experience resistance, leading to a poor prognosis.