The following article features coverage from the 2020 San Antonio Breast Cancer Symposium. Click here to read more of Cancer Therapy Advisor‘s conference coverage.

A study combining nivolumab, abemaciclib, and endocrine therapy as treatment for women with hormone receptor–positive, HER2-negative metastatic breast cancer found that although the combination had some activity, it does not support further investigation because of associated toxicities.

The results were presented by Jun Masuda, of The Cancer Institute Hospital of JFCR, Tokyo, Japan, and colleagues as a poster at the 2020 Virtual San Antonio Breast Cancer Symposium (SABCS).

The phase 2 study enrolled 17 patients with HR-positive, HER2-negative metastatic breast cancer and treated them with 240 mg nivolumab on days 1 and 15, 150 mg abemaciclib twice daily, and either 500 mg fulvestrant of days 1, 15, 19 and every 4 weeks, or 2.5 mg letrozole once daily until disease progression or unacceptable toxicity.

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According to the researchers, enrollment was closed and treatment was discontinued mid-study due to safety concerns.

Six of the 17 patients had experienced grade 3 or more hepatic toxicities leading to treatment discontinuation. All patients had at least 1 adverse event, and 92% and 100% of patients on the fulvestrant arm and the letrozole arm, respectively had a grade 3 or worse event. The most common grade 3 or worse events for the fulvestrant arm were neutropenia, decreased white blood cell count, and elevated liver function tests; the most common for the letrozole arm were neutropenia and elevated liver function tests.

Immune-related adverse events took place in 92% of patients assigned fulvestrant and 100% of patients treated with letrozole. Grade 3 or worse immune-related adverse events occurred in 67% and 60% of the groups, respectively.

ILD/pneumonitis occurred in three patients including one patient with a fatal outcome.

The objective response rate was 55% for fulvestrant and 40% with letrozole. The disease control rates were 91% and 80.0%, respectively. Because the study was stopped early, progression-free and overall survival were undetermined.

The researchers noted that toxicity profiles vary by cyclin-dependent kinase 4/6 (CDK4/6) inhibitor; therefore, treatment with a different inhibitor may improve tolerability.

Read more of Cancer Therapy Advisor‘s coverage of the 2020 SABCS meeting by visiting the conference page.


Masuda J, Tsurutani J, Masuda N, et al. Phase II study of nivolumab in combination with abemaciclib plus endocrine therapy in patients with HR+, HER2- metastatic breast cancer: WJOG11418B NEWFLAME trial. Presented at: 2020 Virtual San Antonio Breast Cancer Symposium (SABCS); December 8-11, 2020. Abstract PS12-10.