... A dose of 1.1 mg/m2 trabectedin every 3 weeks and 150 mg olaparib twice daily was selected for future studies.
The overall response rate (ORR) across all dose levels was 14% (7 of 50 patients), with all responses occurring in patients with STS. The 6-month progression-free survival (PFS) was 26%, and the median overall survival (OS) for all treated patients was 11 months. There was no correlation between BRCA expression or BRCAness and response. However, patients with high PARP1 expression had improved outcomes compared to patients with low PARP1 expression, suggesting a potential role for PARP1 expression as a biomarker. The 6-month PFS in patients with high PARP1 expression was 59%, compared to 8% in patients with low PARP1 expression (HR 0.37, P = .01).
Based on these results, the investigators concluded that the combination of trabectedin and olaparib is active in advanced STS .
Cristina Cruz; Alba Llop-Guevara; Judy E. Garber; Banu K. Arun; José A. Pérez Fidalgo; Ana Lluch; Melinda L. Telli; Cristian Fernández; Carmen Kahatt; Carlos M. Galmarini; Arturo Soto-Matos; Vicente Alfaro; Aitor Pérez de la Haza; Susan M. Domchek; Silvia Antolin; Linda Vahdat; Nadine M. Tung; Rafael Lopez; Joaquín Arribas; Ana Vivancos; José Baselga; Violeta Serra; Judith Balmaña; Steven J. Isakoff .
Purpose
This multicenter phase II trial evaluated lurbinectedin (PM01183), a selective inhibitor of active transcription of protein-coding genes, in patients with metastatic breast cancer. A unicenter translational substudy assessed potential mechanisms of lurbinectedin resistance.
Patients and Methods
Two arms were evaluated according to germline BRCA1/2status: BRCA1/2 mutated (arm A; n = 54) and unselected (BRCA1/2 wild-type or unknown status; arm B; n = 35). Lurbinectedin starting dose was a 7-mg flat dose and later, 3.5 mg/m2 in arm A. The primary end point was objective response rate (ORR) per Response Evaluation Criteria in Solid Tumors (RECIST). The translational substudy of resistance mechanisms included exome sequencing (n = 13) and in vivo experiments with patient-derived xenografts (n = 11) from BRCA1/2-mutated tumors.
Results
ORR was 41% (95% CI, 28% to 55%) in arm A and 9% (95% CI, 2% to 24%) in arm B. In arm A, median progression-free survival was 4.6 months (95% CI, 3.0 to 6.0 months), and median overall survival was 20.0 months (95% CI, 11.8 to 26.6 months). Patients with BRCA2 mutations showed an ORR of 61%, median progression-free survival of 5.9 months, and median overall survival of 26.6 months. The safety profile improved with lurbinectedin dose adjustment to body surface area. The most common nonhematologic adverse events seen at 3.5 mg/m2 were nausea (74%; grade 3, 5%) and fatigue (74%; grade 3, 21%). Neutropenia was the most common severe hematologic adverse event (grade 3, 47%; grade 4, 10%). Exome sequencing showed mutations in genes related to the nucleotide excision repair pathway in four of seven tumors at primary or acquired resistance and in one patient with short-term stable disease. In vivo, sensitivity to cisplatin and lurbinectedin was evidenced in lurbinectedin-resistant (one of two) and cisplatin-resistant (two of three) patient-derived xenografts.
Conclusion
Lurbinectedin showed noteworthy activity in patients with BRCA1/2 mutations. Response and survival was notable in those with BRCA2 mutations. Additional clinical development in this subset of patients with metastatic breast cancer is warranted.











































