Cancer: Triple treatment for gastric tumours

Combining immunotherapy with chemotherapy and targeted agents has the potential to improve the outcome of patients with advanced HER2-positive gastric tumours, a Nature paper suggests. The study, based on interim analyses of a phase III clinical trial, has prompted the United States Food and Drug Administration (FDA) to approve use of the treatment in the clinic.

Around 20% of people with advanced gastric or gastro-oesophageal junction adenocarcinomas overexpress the human epidermal growth factor receptor 2 protein (HER2). For more than a decade, the standard first-line treatment has been combination therapy with the anti-HER2 antibody trastuzumab and chemotherapy.

As part of the KEYNOTE-811 phase III clinical trial, Yelena Janjigian and colleagues assessed the benefits of adding an extra drug called pembrolizumab to the combination. Pembrolizumab is an antibody that helps the immune system to recognize and attack tumour cells. Efficacy data were generated from 264 patients enrolled in the trial. Adding pembrolizumab to trastuzumab and chemotherapy reduced tumour size, induced complete responses (temporary remission) in some participants (increasing the rate of complete responses from 3.1% to 11.3%), and significantly increased the proportion of patients that had favourable responses, the team found.

Given the promising results in this trial, the authors suggest that the same triple treatment be tested in patients with earlier stages of the disease. The trial will continue to monitor the effect of the combination treatment on patient survival.