Novel combination treatment effective in recurrent ER-positive endometrial cancer

Researchers from a phase 2 study report that combination treatment with abemaciclib and letrozole shrinks or stabilizes tumors in a majority of subjects diagnosed with recurrent or persistent estrogen receptor-positive, or ER-positive, endometrial cancer.

The findings were presented in March of 2022 at the Society of Gynecologic Oncology Annual Meeting on Women’s Cancer.

“Letrozole/abemaciclib demonstrated encouraging and durable evidence of activity in recurrent ER-positive endometrial cancer and may [be] an effective endocrine therapy approach for patients with recurrent ER-positive endometrioid endometrial cancer,” said lead investigator Panagiotis Konstantinopoulos, MD, PhD, director of gynecologic oncology translational research at Dana-Farber Cancer Institute in Boston and associate professor of medicine at Harvard Medical School.

As background Konstantinopoulos noted, “In prior studies, aromatase inhibitor monotherapy exhibits limited activity in endometrial cancer, with response rates for both letrozole and anastrozole below 10%. For this reason, development of novel strategies to improve the efficacy of endocrine therapy represents an unmet need and an area of active investigation in endometrial cancer.”

The investigators tested the efficacy of 150 mg of abemaciclib twice daily and 2.5 mg of letrozole once daily in 28 subjects diagnosed with recurrent ER-positive endometrial cancer.

Progression-free survival at 6 months was 55.6%, with a median progression-free survival of 9.1 months.

At the median follow-up of 12.5 months, the researchers found that 75% of tumors had shrunk or stabilized. Notably, about 30% of the tumors shrank by at least 30%.

Two patients withdrew due to side-effects of treatment.

“Based on our findings, the letrozole/abemaciclib combination should be considered worthy of further evaluation for patients with recurrent ER-positive endometrial cancer,” Konstantinopoulos added.