New Reference: Olaparib for PALB2 or BRCA1/2 Mutated Breast Cancer

The phase II TBCRC 048 study found olaparib to be effective in metastatic breast cancer patients with germline PALB2 or somatic BRCA1/2 mutations. The overall response rate was significantly higher in those with PALB2 mutations compared to those with somatic BRCA mutations. Olaparib was well tolerated, with manageable side effects.

Study

Phase II study [TBCRC 048]

Metastatic breast cancer patients with germline PALB2 mutations or somatic BRCA1/2 mutations

Olaparib 300 mg twice daily until progression

Efficacy

ORR: 75% vs 36.7% (gPALB2m vs. sBRCAm)

Median PFS: 9.4 mos vs 5.5 mos

Median DOR: 7.0 mos vs 11.2 mos

Safety

Grade 3 anemia (13%), grade 2 alopecia (2%)

Dose reductions required in 40.7%; 1 discontinuation due to grade 3 anemia

J Clin Oncol 2026;00:1-9

Tung NM, Robson ME, Li T TBCRC 048 (Olaparib Expanded) Expansion Cohorts: Phase II Study of Olaparib Monotherapy for Patients With Metastatic PALB2 Germline Mutations or Somatic BRCA1/2 Mutations

http://doi.org/10.1200/JCO-25-02075

Reviewed by Ulas D. Bayraktar, MD on Feb 15, 2026

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