Pfizer and Merck have begun two Phase III studies of avelumab, a potential treatment for advanced or metastatic gastric / gastro-esophageal junction (GEJ) cancers.

Avelumab is an investigational, fully human anti-PD-L1 IgG1 monoclonal antibody.

The trials will investigate avelumab in first and third-line settings, with overall survival (OS) as the primary endpoint.

Javelin Gastric 100 is a study comparing the switch from first-line chemotherapy to maintenance therapy with avelumab, versus continuation of chemotherapy.

This trial will evaluate maintenance therapy with avelumab in patients with unresectable, locally advanced, or metastatic gastric / GEJ cancers whose disease has not progressed with first-line platinum-based chemotherapy.

Around 629 patients will be enrolled in the trial across more than 220 sites in Asia Pacific, Europe, North America and South Americal.

"We are continuing the fight against cancer with an overarching goal of potentially improving survival."

Javelin Gastric 100 is the only gastric cancer trial designed to evaluate superiority of an immunotherapy compared with conventional platinum-based chemotherapy as a first-line maintenance treatment.

Merck Global biopharma business Research & Development head Dr Luciano Rossetti said: "The prognosis is generally poor for the majority of patients with advanced gastric cancers.

"By initiating these two Phase III trials in gastric and gastro-esophageal junction cancers, we are continuing the fight against cancer with an overarching goal of potentially improving survival for patients."

Javelin Gastric 300 is a third-line study evaluating avelumab in patients with unresectable, recurrent, or metastatic gastric / GEJ cancers.

Avelumab will be compared with an investigator’s chosen chemotherapy from a pre-specified list of therapeutic options.

This trial will enrol around 330 patients at about 170 sites in Asia, Australia, Europe, North America and South America.

Pfizer Oncology chief medical officer and Clinical Development and Medical Affairs senior vice-president Dr Mace Rothenberg said: "We are continuing to investigate avelumab in cancers with high unmet need and where there is a strong rationale for immunotherapeutic intervention.

"Advanced gastric cancer is a challenging diagnosis to face as a patient, and we are dedicating significant resources to evaluate avelumab as a potential new treatment option for patients in multiple settings of this disease."

The clinical development programme for avelumab currently includes more than 1,500 patients, who have been treated across more than 15 tumour types.

These tumours include breast cancer, gastric / GEJ cancers, head and neck cancer, Merkel cell carcinoma, melanoma, mesothelioma, non-small cell lung cancer, ovarian cancer, renal cell carcinoma, and urothelial cancer.