The following article features coverage from the ASCO Gastrointestinal Cancers Symposium 2022. Click here to read more of Cancer Therapy Advisor’s conference coverage.

Neoadjuvant treatment with immune checkpoint inhibitors, followed by surgery and adjuvant immunotherapy, appears effective for patients with microsatellite instability-high/mismatch repair deficient (MSI/dMMR) gastric or gastroesophageal junction (GEJ) adenocarcinoma, phase 2 data suggest.

The results raise the question of whether surgery can be delayed or avoided for some patients with localized MSI/dMMR gastric/GEJ cancer if immune checkpoint inhibitors are effective, said Thierry Andre, MD, of Sorbonne University in Paris.

Dr Andre presented these results, from the phase 2 NEONIPIGA trial, at the ASCO Gastrointestinal Cancers Symposium 2022.

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The trial ( Identifier: NCT04006262) included 32 patients with resectable MSI/dMMR gastric/GEJ adenocarcinoma. The median age was 65 (range, 40-84) years, and 72% of patients were men.

All 32 patients started neoadjuvant treatment with nivolumab at 240 mg every 2 weeks and ipilimumab at 1 mg/kg every 6 weeks. There were 29 patients who went on to surgery 5 weeks after the last injection of nivolumab.

One patient did not have surgery because of metastatic disease progression, and 2 patients refused surgery because they had achieved a complete response to immunotherapy.

After surgery, 25 patients received adjuvant nivolumab at 480 mg every 4 weeks, and 10 patients were still receiving adjuvant therapy at last follow-up.

The study’s primary endpoint was pathologic complete response (pCR), and the pCR rate was 58.6% (17/29).

The median follow-up was 12 months. There was 1 death at day 3 after surgery, and 1 patient had progressive disease after 6 cycles of treatment. The patient who progressed did not undergo surgery.

A total of 31 patients were still alive at last follow-up, and 30 had not relapsed. This translates to an event-free survival rate of 94%.

In all 32 enrolled patients, the rate of grade 3/4 treatment-related adverse events was 25%. Peri and/or post-operative complications (until 90 days after surgery) occurred in 58.5% of patients. Surgical complications were as expected, Dr Andre said.

Disclosures: This research was supported by GERCOR and Bristol Myers Squibb. Some study authors declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of disclosures.

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Andre T, Tougeron D, Piessen G, et al. Neoadjuvant nivolumab plus ipilimumab and adjuvant nivolumab in patients (pts) with localized microsatellite instability-high (MSI)/mismatch repair deficient (dMMR) oseo-gastric adenocarcinoma (OGA): The GERCOR NEONIPIGA phase II study. Presented at ASCO GI 2022; January 20-22, 2022. Abstract 244.