Adding Atezolizumab to Chemo Improves Survival in Triple-Negative Breast Cancer

The combination of atezolizumab and carboplatin improves survival outcomes over carboplatin alone in patients with metastatic triple-negative breast cancer (TNBC), according to research published in JAMA Oncology.

Researchers found that adding atezolizumab to carboplatin prolonged both progression-free survival (PFS) and overall survival (OS) in a phase 2 trial.

The trial (ClinicalTrials.gov Identifier: NCT03206203) included 106 patients with metastatic TNBC who had received up to 1 prior treatment for metastatic disease.

The patients had a mean age of 55 (range, 27-79) years, 100% were women, and 69% were White. Most (82%) had received prior chemotherapy, including as adjuvant treatment only (33%), as neoadjuvant and adjuvant treatment (20%), and as metastatic treatment (32%).

The patients were randomly assigned to receive either atezolizumab plus carboplatin (n=56) or carboplatin alone (n=50). Patients in the carboplatin-alone arm who experienced disease progression were permitted to cross over to atezolizumab monotherapy.

Patients received atezolizumab plus carboplatin for a median of 17.4 weeks and carboplatin alone for a median of 15.4 weeks. Nineteen patients crossed over from the carboplatin-alone arm and received atezolizumab monotherapy.

The median PFS was 4.1 months with atezolizumab plus carboplatin and 2.2 months with carboplatin alone (hazard ratio [HR], 0.66; 95% CI, 0.44-1.01; P =.05).

The median OS was 12.6 months with the combination and 8.6 months with chemotherapy alone (HR, 0.60; 95% CI, 0.37-0.96; P =.03).

When patients who crossed over were excluded from the OS analysis, there was a greater improvement in OS with atezolizumab. The median OS was 12.6 months with atezolizumab plus carboplatin and 7.0 months with carboplatin alone (HR, 0.46; 95% CI, 0.27-0.79; P =.004).

The overall response rate was 30.4% with the combination and 8.0% with carboplatin alone. The clinical benefit rate was 37.5% and 18.0%, respectively.

The most common adverse events (AEs) with the combination were thrombocytopenia, anemia, lymphocytopenia, nausea, fatigue, and increased liver enzymes.

Grade 3-4 serious AEs were more common with the combination than with carboplatin alone — 41% and 8%, respectively. The rate of withdrawal due to toxicity was similar between the arms — 4% and 6%, respectively.

Disclosures: This research was partly supported by Genentech. Some study authors declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of disclosures.

Reference

Lehmann BD, Abramson VG, Dees EC, et al. Atezolizumab in combination with carboplatin and survival outcomes in patients with metastatic triple-negative breast cancer: The TBCRC 043 phase 2 randomized clinical trial. JAMA Oncol. Published online December 14, 2023. doi:10.1001/jamaoncol.2023.5424

This article originally appeared on Cancer Therapy Advisor