The following article features coverage from the San Antonio Breast Cancer Symposium (SABCS) 2017 meeting. Click here to read more of Cancer Therapy Advisor‘s conference coverage.

Pathological complete response (pCR) predicts event-free survival (EFS) and distant recurrence–free survival (DRFS) among women with high-risk breast cancer, according to the first long-term efficacy results from the multicenter, multi-arm, adaptively randomized I-SPY2 platform trial.1 The findings were presented at the 2017 San Antonio Breast Cancer Symposium.

“Achieving pCR through any therapy for any subtype is a sufficient endpoint,” reported lead study author Douglas Yee, MD, of the University of Minnesota in Minneapolis.

The association between pCR and EFS was “significant and clinically impactful” within each subtype, he added.

The findings support the use of pCR as a primary endpoint for accelerated approval of new drugs when EFS is evaluated in the relevant patient population.

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The research team evaluated the association between pCR and EFS in 746 patients. Across all study arms, pCR “was highly associated with 3-year EFS” (94% vs 76%; hazard ratio [HR], 0.20; 95% CI: 0.11-0.36); 3-year DRFS was 95% for patients across treatments achieving pCR vs 79% among those not achieving pCR (HR, 0.20; 95% CI: 0.11-0.37).

Among patients with triple-negative breast cancer (TNBC), pCR also proved strongly predictive of 3-year EFS (pCR vs non-pCR patients: 92% vs 67%; HR, 0.17; 95% CI: 0.07-0.39) and 3-year DRFS (94% vs 70%; HR, 0.16; 95% CI: 0.06-0.40).

Results were similar for patients with hormone receptor–positive/HER2-negative breast cancer.

The findings demonstrate that pCR is a “very strong” surrogate endpoint for improved EFS and DDFS in the high-risk population and across treatments, Dr Yee said.

To date, more than 1200 patients have been randomly assigned to 1 of 14 I-SPY2 groups.

Read more of Cancer Therapy Advisor‘s coverage of the San Antonio Breast Cancer Symposium (SABCS) 2017 meeting by visiting the conference page.

Reference

  1. Yee D, DeMichele A, Isaacs C, et al. Pathological complete response predicts event-free and distant disease-free survival in the I-SPY2 TRIAL. Oral presentation at: 2017 San Antonio Breast Cancer Symposium; December 5-9, 2017; San Antonio, TX.