ESMO Breast 2021: Atezolizumab Plus Carboplatin for Metastatic Invasive Lobular Cancer
Posted: Thursday, June 3, 2021
Hugo M. Horlings, MD, PhD, of the Netherlands Cancer Institute, Amsterdam, and colleagues presented the first results of GELATO—a phase II, single-arm trial of atezolizumab after immune induction with carboplatin in metastatic invasive lobular breast cancer—at the European Society for Medical Oncology (ESMO) Breast Cancer Virtual Congress 2021 (Abstract LBA3). Their results demonstrated a “clear efficacy signal” of PD-L1 blockade in combination with carboplatin, specifically in patients with triple-negative disease.
“In terms of predictive biomarkers, [most] responses in patients with triple-negative invasive lobular breast cancer, stromal tumor-infiltrating lymphocytes, and CD8-positive counts at baseline are not associated with clinical benefit; there is a trend toward higher PD-L1 expression in responding patients, while serial biopsy results are pending,” stated study discussant Sylvia Adams, MD, of NYU Langone Health, New York, in an ESMO press release. “Further translational research should assess if responses are associated with reported immune-related subtype of invasive lobular breast cancer and/or high tumor mutational burden.”
The GELATO trial enrolled 23 patients with metastatic invasive lobular breast cancer. All patients were endocrine-refractory and underwent a maximum of two lines of palliative chemotherapy. Participants were administered 12 weekly cycles of carboplatin at AUC 1.5, and 1,200 mg of atezolizumab was given every 3 weeks beginning at the third carboplatin cycle; treatment continued until intolerability or disease progression.
Four patients were progression-free at 24 weeks; treatment started for two patients, and one has had an ongoing response. A partial response was achieved in four patients, yielding an objective response rate of 19%, and two patients achieved stable disease, leading to a clinical benefit rate of 29%. Of the patients with a clinical benefit, four had triple-negative disease. Clinical benefit was not found to be associated with stromal tumor-infiltrating lymphocytes.
Disclosure: For full disclosures of the study authors, visit oncologypro.esmo.org.