Hence, we investigated the anti-tumour effects of AZD5305 in combination with carboplatin or paclitaxel in a BRCA1m TNBC xenograft, SUM149PT, and BRCA WT TNBC PDX model, HBCx-9. In both models, combination of AZD5305 with carboplatin was well tolerated and demonstrated clear benefit compared to each monotherapy treatment.