The following article features coverage from the European Society for Medical Oncology 2020 virtual meeting. Click here to read more of Cancer Therapy Advisor‘s conference coverage.

The addition of atezolizumab to neoadjuvant chemotherapy resulted in higher pathologic complete response (pCR) rates among women with early triple-negative breast cancer (TNBC), regardless of PD-L1 positivity, according to results from the phase 3 IMpassion031 trial presented at the European Society for Medical Oncology (ESMO) Virtual Congress 2020 and simultaneously published in Lancet.1,2

“This new combination therapy may offer an improved curative treatment option for this patient population with a high unmet medical need,” Nadia Harbeck, MD, PhD, of the Ludwig-Maximilians-Universität München University in Germany, and presenter of the study, said.

The international, double-blind, phase 3 IMpassion031 trial randomly assigned 333 patients with early, treatment-naive TNBC to receive atezolizumab or placebo. In addition, all patients received nab-paclitaxel for 12 weeks followed by doxorubicin plus cyclophosphamide for 8 weeks. Patients then underwent surgery. Patients in the experimental arm received atezolizumab for an additional 11 doses, whereas patients in the placebo arm were observed. Patients were stratified by stage and PD-L1 positivity.

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The coprimary endpoints were pCR in the intention-to-treat (ITT) and PD-L1–positive (tumor-infiltrating immune cells ≥1%). Secondary endpoints were event-free survival, disease-free survival, and overall survival (OS) in the ITT and PD-L1–positive populations, but at press time, OS data were not yet mature.

Baseline characteristics were similar between arms, with a median patient age of 51 years, 63% of patients were white, 26% were Asian, and 7% were Black or African American. Most patients had stage II disease (77%) and 54% had PD-L1–positive disease.

After a median follow-up of approximately 20 months, the pCR in the atezolizumab arm was significantly higher at 57.6% compared with 41.1% in the placebo arm (P =.0044). The benefit was observed regardless of PD-L1–positivity, as patients with PD-L–negative disease in the atezolizumab arm demonstrated a pCR of 47.7% compared with 34.4% in the placebo arm (P =.021), which did not cross the prespecified boundary.

Atezolizumab was favored across all subgroups in the ITT population, Dr Harbeck added.

Rates of any and grade 3 to 4 adverse events (AEs) was similar between arms, but serious treatment-related AEs occurred more frequently in the atezolizumab arm (22.6% vs 15.6%, respectively). The most common serious AEs were febrile neutropenia, pneumonia, and pyrexia. There were no unexpected immune-related AEs, and high-grade immune-related AEs were rare.

Dr Harbeck concluded that “atezolizumab plus chemotherapy resulted in a statistically significant and clinically meaningful plus 16.5% increase in pCR rate vs placebo plus chemotherapy.”

Disclosures: F. Hoffmann-La Roche, Ltd. funded this study. Some of the presenters reported financial relationships with the pharmaceutical industry; for a full list of disclosures, please refer to the original abstract.

Read more of Cancer Therapy Advisor‘s coverage of the ESMO Virtual Congress 2020 by visiting the conference page.

Reference

  1. Harbeck N, Zhang H, Barrios CH, et al. IMpassion031: Results from a phase III study of neoadjuvant (neoadj) atezolizumab + chemotherapy in early triple-negative breast cancer (TNBC). Presented at: European Society for Medical Oncology (ESMO) Virtual Congress 2020; September 19-21, 2020. LBA11.
  2. Mittendorf EA, Zhang H, Barrios CH, et al. Neoadjuvant atezolizumab in combination with sequential nab-paclitaxel and anthracycline-based chemotherapy versus placebo and chemotherapy in patients with early-stage triple-negative breast cancer (IMpassion031): a randomised, double-blind, phase 3 trial. Lancet. Published online September 20, 2020. doi:10.1016/S0140-6736(20)31953-X

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Breast Cancer ESMO Virtual Congress 2020