Immunotherapy drug works as well as chemotherapy in advanced patients


CHICAGO – In a practice-changing study, researchers here suggested that patients diagnosed with advanced gastric cancer can be treated with the immunotherapy agent pembrolizumab (Keytruda) rather than chemotherapy.

At 12 months, the overall survival of patients treated with pembrolizumab was 47% compared with 46% for patients treated with chemotherapy – a difference that fulfilled the pre-specified non-inferiority criteria, reported Josep Tabernero, MD, PhD, head of medical oncology at Vall d’Hebron Barcelona Hospital University Hospital and Institute of Oncology.

But this “non-inferior” finding is clinically significant said Richard Schilsky, MD, chief medical officer of American Society of Clinical Oncology because “Platinum-based chemotherapy is a tough therapy for gastric cancer patients, many of who are frail and undernourished, and if you had an alternative such as pembrolizumab that is not any worse than chemotherapy and has a much more favorable side effect profile, I would switch in a minute.” Shilsky moderated an ASCO 2019 press conference where Tabernero reported the KEYNOTE-062 results.

Tabernero said overall survival in these patients was 10.6 months with pembrolizumab and 11.1 months with chemotherapy (P=0.162 for superiority).

But the combination of pembrolizumab and chemotherapy did not offer patients a benefit over pembrolizumab alone, Tabernero said.

Adverse events in the trial were less frequent among patients treated with pembrolizumab, he said. In the combination therapy 73.2% of patients had a Grade 3-5 adverse event; in the chemotherapy arm alone, 69.3% of the patients had a Grade 3-5 adverse event, but in the pembrolizumab monotherapy patients the adverse event rate was 16.9%.

In the trial, Tabernero and colleagues enrolled 763 patients diagnosed with locally advanced, unresectable or metastatic gastric or gastroesophageal adenocarcinoma who were HER2-negative and had PDL-1 positive disease. The researchers assigned 256 patients to receive 200 mg of pembrolizumab every 3 weeks for as long as 35 cycles; assigned 257 patients to the same pembrolizumab regimen plus chemotherapy; and assigned 250 patients to placebo plus chemotherapy.

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Disclosure:

The study was funded by Merck.

Tabernero disclosed relevant relationships with Bayer, Boehringer Ingelheim, Lilly, MSD, Merck Serono, Novartis, Sanofi, Taiho Pharmaceutical, Merrimack, Peptomyc, Rafael Pharmaceuticals, Symphogen, Chugai Pharma, Ipsen, Merus, Pfizer, Seattle Genetics, Array BioPharma, AstraZeneca, BeiGene, Genentech, Genmab, Halozyme,Imugene, Inflection Biosciences, Kura, Menarini, Molecular Partners, Pharmacyclics, ProteoDesign, Roche, Seattle Genetics, Servier, VCN Biosciences, Biocartis, Foundation Medicine, HalioDx and Roche Diagnostics.

Schilsky disclosed relevant relationships with AstraZeneca, Bayer, Bristol-Myers Squibb, Genentech/Roche, Lilly, Merck, and Pfizer.

Source:  Tabernero J, et al “Pembrolizumab with or without chemotherapy versus chemotherapy in advanced G/GEJ adenocarcinoma: The phase 3, KEYNOTE-062 study,” ASCO 2019.