The following article features coverage from the European Society for Medical Oncology (ESMO) World Congress on Gastrointestinal Cancer 2021. Click here to read more of Cancer Therapy Advisor‘s conference coverage.

Adding pembrolizumab to first-line standard care improved overall response rates in patients with HER2-positive, unresectable or metastatic gastric or gastroesophageal junction cancer in the phase 3 KEYNOTE-811 trial.1

These results were presented at the European Society for Medical Oncology (ESMO) World Congress on Gastrointestinal Cancer 2021 by Yelena Y. Janjigian, MD, of Memorial Sloan Kettering Cancer Center in New York, New York.

In the ongoing KEYNOTE-811 study (ClinicalTrials.gov Identifier: NCT03615326), researchers are comparing pembrolizumab plus trastuzumab and chemotherapy with placebo plus trastuzumab and chemotherapy. The chemotherapy options are 5-fluoracil plus cisplatin or capecitabine plus oxaliplatin. 

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Patients enrolled on the trial have unresectable or metastatic HER2-positive disease, have received no prior systemic therapy in the advanced setting, and have an Eastern Cooperative Oncology Group score of 0 or 1.

Dr Janjigian presented results for 264 patients in the efficacy population. This included 133 patients in the pembrolizumab arm and 131 in the placebo arm. In both arms, most patients received the capecitabine-oxaliplatin chemotherapy regimen (86% and 88%, respectively). 

The median follow-up was 12 months. The confirmed overall response rate was 74.4% in the pembrolizumab arm and 51.9% in the placebo arm, corresponding to a difference of 22.7% (P =.00006).

The complete response rate was 11% in the pembrolizumab arm and 3% in the placebo arm. The disease control rates were 96.2% and 89.3%, respectively. The duration of response was 10.6 months and 9.5 months, respectively.

The safety population included 217 patients from the pembrolizumab arm and 216 from the placebo arm. Grade 3 to 5 adverse events occurred in 57% of patients in both arms. There were 7 fatal adverse events in the pembrolizumab arm and 10 in the placebo arm.

Dr Janjigian noted that, based on these data, pembrolizumab was recently granted accelerated approval in the United States for use in combination with trastuzumab and chemotherapy as first-line treatment for locally advanced, unresectable or metastatic HER2-positive gastric or gastroesophageal junction adenocarcinoma.2

Disclosures: This research was supported by Merck Sharp & Dohme Corp. Dr Janjigian declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of disclosures.

Read more of Cancer Therapy Advisor’s coverage of the ESMO World Congress on Gastrointestinal Cancer 2021 by visiting the conference page.

Reference

  1. Janjigian YY, Kawazoe A, Yañez P, et al. Pembrolizumab plus trastuzumab and chemotherapy for HER2+ metastatic gastric or gastroesophageal junction cancer: Initial findings of the global phase 3 KEYNOTE-811 study. Presented at: ESMO World Congress on Gastrointestinal Cancer; June 30-July 3, 2021. Abstract LBA-4.
  2. FDA approves Merck’s Keytruda (pembrolizumab) combined with trastuzumab and chemotherapy as first-line treatment in locally advanced unresectable or metastatic HER2-positive gastric or gastroesophageal junction adenocarcinoma. News release. Merck. May 5, 2021. https://bit.ly/2SjmdOj

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ESMO GI 2021 Gastrointestinal Cancer