Clinical Summary:

• Design/Population: This phase 2 trial evaluated neoadjuvant nivolumab in patients with resectable mismatch repair-deficient endometrial cancer. 
• Key Outcomes: Nivolumab produced high clinical complete response rates and major pathological responses, with some patients able to avoid surgery. No disease progression or recurrence was observed during follow-up. 
• Clinical Relevance: These findings support further investigation of neoadjuvant PD-1 blockade as a potential organ-preserving strategy for patients with MMRd endometrial cancer.

Results from a phase 2 study demonstrated that neoadjuvant nivolumab induced high rates of complete response among patients with resectable mismatch repair-deficient endometrial cancer.

These findings were presented by Jung-Yun Lee, MD, Yonsei Cancer Center and Severance Hospital, Seoul, South Korea, at the European Society for Medical Oncology (ESMO) Gynecological Cancers Congress in Copenhagen, Denmark. 

In this multicenter, single-arm trial, 26 patients with clinical stage I-IIIC2 mismatch repair-deficient or microsatellite instability-high endometrial cancer received 480 mg of intravenous nivolumab once every 4 weeks for up to 6 months prior to planned surgery and/or adjuvant therapy. Patients who achieved a clinical complete response following nivolumab were permitted to omit surgery and adjuvant treatment. The primary end point was complete response rate. A key secondary end point was safety. 

The study met its primary end point during the first stage of enrollment, with 13 of the first 15 patients achieving a complete response. 

At analysis, among 22 patients were evaluable for response, 68.2% of patients achieved clinical complete response and 31.8% of patients achieved major pathological response. Among patients who achieved clinical complete response, 46.67% of patients were able to forgo surgery. No incidences of disease progression or recurrence were observed during the follow-up period. 

No grade ≥3 adverse events were reported, and no treatment-related adverse events led to treatment discontinuation.

“Nivolumab was feasible and provided meaningful clinical complete response in patients with [mismatch repair-deficient] surgically resectable endometrial cancer,” concluded Dr Lee. 

Source:

Lee YJ, Lee Y, Park J, et al. A phase II study of induction PD-1 blockade (nivolumab) in patients with surgically completely resectable mismatch repair deficient endometrial cancer (NIVEC). Presented at ESMO Gynecological Cancers Congress. June 17-19, 2026. Copenhagen, Denmark. Abstract 70O.