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TOPLINE:

Using olaparib alone or in combination with durvalumab as a chemotherapy-free maintenance treatment can extend progression-free survival (PFS) in patients with advanced triple-negative breast cancer (TNBC).

METHODOLOGY:

• First-line standard therapy for advanced TNBC generally includes taxane- or platinum-based chemotherapy which poses challenging toxicities. Exploring chemotherapy-free maintenance strategies may provide adequate disease control and improve patient quality of life.
• The researchers evaluated 45 patients, at five sites in the Republic of Korea, the United States, and Singapore, with TNBC who had ongoing stable disease or complete/partial response from first- or second-line platinum-based chemotherapy.
• The patients were randomized 1:1 to receive olaparib 300 mg twice daily with or without durvalumab 1500 mg on day 1 every 4 weeks.
• The authors compared PFS with a historical control of continued platinum-based therapy. An improvement to 4 months with maintenance therapy was considered clinically significant.

TAKEAWAY:

• After a follow-up of 9.8 months, patients who received olaparib alone demonstrated median PFS of 4.0 months, and those who received the combination therapy had median PFS of 6.1 months.
• Clinical benefit rates, defined as stable disease for at least 24 weeks or complete/partial response, were reported in 44% of the monotherapy group and 36% of the combination therapy group.
• Sustained clinical benefit was evident irrespective of germline BRCA mutation or programmed death-ligand 1 status, although it tended to be associated with complete or partial response to prior platinum.
• Grade 3-4 adverse events were reported in nine patients (39%) in the olaparib arm and eight patients (36%) in the combination arm. No treatment-related deaths or new safety signals were observed.

IN PRACTICE:

"Maintenance regimens are rarely used in [triple-negative breast cancer] but offer the possibility of more tolerable long-term treatment avoiding some of the chemotherapy-related side effects of more aggressive regimens, as is standard in the first-line treatment of HER2-positive advanced breast cancer," the researchers concluded.

SOURCE:

This study, led by Tira J. Tan from Duke-NUS Medical School, Singapore, was published online on January 18, 2024, in Clinical Cancer Research.

LIMITATIONS:

The main limitations were the small sample size and lack of a standard control arm. Most patients (76%) were Asian, limiting generalizability. The trial was not designed to compare olaparib monotherapy and olaparib plus durvalumab regimens.

DISCLOSURES:

AstraZeneca Pharmaceuticals LP supported this study. Several authors reported financial support from various sources.