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10-05-2021 | ESMO Breast 2021 | Conference coverage | News

GELATO: Atezolizumab–carboplatin promising for metastatic lobular breast cancer

Author: Shreeya Nanda

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medwireNews: Early results from the GELATO trial point to the potential of atezolizumab plus carboplatin for the treatment of metastatic invasive lobular breast cancer (ILC).

The phase 2 findings were presented at the ESMO Breast Cancer Virtual Congress 2021 by Leonie Voorwerk, from the Netherlands Cancer Institute in Amsterdam.

Noting that ILC “is a special histological breast cancer subtype” that has “limited” options after endocrine treatment, she explained that the combination of immune checkpoint blockade and platinum chemotherapy has previously shown activity in a mouse model of metastatic ILC.

The GELATO researchers therefore recruited 23 patients with metastatic ILC characterized by negative or aberrant E-cadherin who had received no more than two prior lines of palliative chemotherapy; individuals with hormone receptor (HR)-positive disease needed to be refractory to endocrine therapy to be eligible for inclusion.

The median age of the participants was 60 years and the majority (79%) had HR-positive disease, while 22% had triple-negative disease. About half (48%) of the patients had not received any palliative chemotherapy and 70% had been treated with CDK4/6 inhibitors.

Participants received up to 12 cycles of weekly carboplatin AUC 1.5 mg/mL per min, with atezolizumab – at a dose of 1200 mg every 3 weeks – initiated from the third carboplatin cycle.

Four patients had a partial response, which lasted for a median of 12 weeks, and another two had stable disease for at least 6 months. Therefore, the objective response rate and clinical benefit rate were 19% and 29%, respectively.

Of note, four participants were progression-free at the 24-week timepoint, meaning that the primary endpoint of the first stage of the trial was met, said Voorwerk. The median duration of progression-free survival was 14.6 weeks.

Four of the six patients who derived any clinical benefit from the combination had triple-negative ILC, highlighted the presenter.

She added that there was no association between clinical benefit and baseline stromal tumor-infiltrating lymphocyte levels or CD8+ cell counts, but 60% of those who benefited were PD-L1-positive (≥1% expression on immune cells as measured by the SP142 assay).

And Voorwerk concluded: “Further translational research is needed to provide the rationale for new strategies to improve checkpoint blockade in patients with lobular breast cancer.”

Sylvia Adams (Perlmutter Cancer Center, New York, USA), who discussed the findings, said that it was difficult to ascertain the contribution of the individual agents given the single-arm nature of the study, and wondered whether the use of a CTLA-4 inhibitor could further improve response rates and durability.

medwireNews is an independent medical news service provided by Springer Healthcare Ltd. © 2021 Springer Healthcare Ltd, part of the Springer Nature Group

ESMO Breast Cancer Virtual Congress 2021; 5–8 May

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