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Vahdat presents promising new treatment for triple negative breast cancer

Friday, December 9, 2016

This is an excerpt of a story that appeared in OncLive. Read the whole article here.

Photo of Linda Vahdat, M.D.Linda Vahdat, M.D. Treatment with sacituzumab govitecan (IMMU-132) was well-tolerated and induced durable responses, some lasting longer than 1 year, for heavily pretreated patients with metastatic triple-negative breast cancer (TNBC), according to findings from an ongoing phase I/II study presented at the 2016 San Antonio Breast Cancer Symposium (SABCS).

In the single-arm trial, the confirmed objective response rate (ORR) was 30% with sacituzumab govitecan, and the duration of response was 8.9 months (95% CI, 6.1-11.3). The median progression-free survival was 6.0 months (95% CI, 5.0-7.3) and the median overall survival was 16.6 months (95% CI, 11.1-20.6).

"The findings are truly outstanding," said senior study author Linda T. Vahdat, M.D., MBA, from Weill Cornell Medicine and NewYork-Presbyterian Hospital. "The confirmed response rate is near 30%, and what's really striking is that this is a group of patients with a median of 5 prior regimens for breast cancer—it is a very heavily pretreated population."

Sacituzumab govitecan is an antibody-drug conjugate that consists of the active metabolite of irinotecan, SN-38, linked with a humanized IgG antibody targeted against TROP-2, a cell-surface glycoprotein that is expressed in more than 90% of TNBC. The ongoing study enrolled 69 patients with relapsed/refractory metastatic TNBC. 

The complete response (CR) rate with sacituzumab govitecan was 3% and the partial response (PR) rate was 28%. Additionally, 45% of patients had stable disease (SD), with 16% of the responses lasting for ≥6 months. The clinical benefit rate (CR + PR + SD ≥6 months) was 46%. After a median follow-up of 16.6 months, 7 patients continued to receive therapy, with 6 continuing to respond at the time of the analysis. There were 3 durable responses that lasted 13 to 21 months.

"These aren't just flash in the pan type of responses, they are actually quite durable," said Vahdat. "When you have a drug that you can keep someone on in triple-negative breast cancer for almost a year you get excited, because the median survival in TNBC is a little under a year."

Data from the ongoing phase I/II study will be submitted to the FDA for a potential accelerated approval, according to the poster presented at SABCS. This submission would be completed under a breakthrough therapy designation received in February 2016 for the medication in TNBC following at least 2 treatments for metastatic disease. A phase III study is currently being planned under a special protocol agreement with the FDA.