Complete remission with olaparib in BRIP1-mutated metastatic high-grade pleomorphic sarcoma: case study and literature review – an example of a genomic profiling-based tumor treatment, in a cancer type with high unmet clinical need

Background and purpose: Patients with high-grade metastatic sarcoma have a poor prognosis and limi­ted treatment options, mostly involving chemotherapy with palliative intent. In the past years, nextgeneration sequencing has proven its benefit in cancer diagnostics and prediction of treatment response to targeted therapy. Patient/material and methods: We present a case of response and long-term complete remission under treatment with the poly(ADP-ribose) polymerase inhibitor (PARP-inhibitor) olaparib in a patient with meta­static high-grade pleomorphic sarcoma, with an next generation sequencing detected BRIP1-mutation. Additionally, a literature search regarding the pathophysiology of BRIP1-mutations and the role of PARP-inhibitors in BRIP1-mutated cancer was conducted. Results: A 67-year-old female patient was diagnosed with a high-grade intra-abdominal pleo­morphic sarcoma, which was surgically resected. One year later, metastatic lesions in the right lung were observed. Genomic profiling identified a BRIP1-mutation. Based on this finding, the patient was included in the PRECISION-2 olaparib study, which evaluates the efficacy of olaparib in advanced cancers of any type harboring mutations in a homologous recombination gene. Within 2 months of ola­parib treatment, regression of the pulmonary metastases was observed with ongoing complete remission for currently 36 months. A review of the available literature highlights the importance of BRIP1 in the homologous recombination repair pathway and its role as a cancer susceptibility gene. Studies in BRIP1-mutated breast cancer, ovarian cancer, and prostate cancer suggest a clinical benefit of PARP-inhibitor use. Interpretation: We here describe the first case of a metastatic BRIP1-mutated sarcoma, undergoing a complete radiologic response to olaparib treatment. We highlight an underexplored role of homologous recombination deficiency in non-traditional cancer types and postulate a tumor-agnostic approach to the use of PARP-inhibitors in BRIP1-mutated tumors.