Interim findings from the PLATFORM study do not support the use of capecitabine or durvalumab maintenance therapy versus surveillance in patients with advanced oesophago-gastric adenocarcinoma (OGA), according to data being presented at the virtual 2020 ASCO Annual Meeting.

“Advanced OGA patients are treated with platinum-based 1st line chemotherapy but the role of maintenance therapy once disease control is obtained is unknown,” wrote David Cunningham, MD, The Royal Marsden NHS Foundation Trust, London, United Kingdom, and co-investigators, who sought to evaluate the role of maintenance therapy in patients with HER2-negative advanced OGA that responded to or was stabilized with first-line platinum-based chemotherapy.

The primary end point of the phase 2 trial is progression-free survival.

Thus far, a total of 1053 patients have been recruited for the study, and 356 have been randomized to undergo surveillance or receive capecitabine, durvalumab, rucaparib, or capecitabine plus ramucirumab.

A futility interim analysis occurred when 61 patients had been recruited to a treatment arm and were deemed evaluable based on a 12-week progression-free rate.

The 12-week progression-free rates observed in the interim analyses were 51% in the surveillance arm, 52% in capecitabine arm, and 49% in the durvalumab arm.

In addition, biomarker analyses of the surveillance and durvalumab arms included PD-L1 as tumor and immune cell combined proportion (TIP), multiplex IHC of tumor infiltrating lymphocytes, tumor mutational burden, and microsatellite instability status.

Dr Cunningham et al found that in the surveillance arm, among patients with PD-L1 TIP <10% and ≥10%, the 12-week progression-free rates were 53% and 43%, respectively. In the durvalumab arm, progression-free rates were 51% and 100%, respectively.

“PLATFORM IA did not indicate futility in maintenance capecitabine or durvalumab compared to surveillance in advanced OGA and will continue to target accrual,” the investigators wrote, adding that partial responses were observed only with maintenance durvalumab.—Kaitlyn Manasterski

Cunningham D, Yeak Kit Fong C, Peckitt C et al. Evaluating maintenance therapies in advanced oesophago-gastric adenocarcinoma (OGA): Interim analysis and biomarker results from the PLATFORM study. Presented at: the 2020 ASCO Annual Meeting; May 29-31, 2020. Abstract 282.