Black Diamond Therapeutics Granted Fast Track Designation by the FDA for BDTX-189 for the Treatment of Adult Patients with a Solid Tumor Harboring an Allosteric HER2 Mutation or an EGFR or HER2 Exon 20 Insertion Mutation - Seite 2

About MasterKey-01

MasterKey-01 (NCT04209465) is a combined Phase 1/2 open-label, two-part, multicenter study to assess the safety, tolerability, pharmacokinetics, and anti-tumor activity of BDTX-189, in adult patients with advanced solid tumors who have no standard therapy available or for whom standard therapy is considered unsuitable or intolerable. Part A is a Phase 1, first-in-human, open-label dose escalation study, comprised of initial single-patient, accelerated titration cohorts followed by multiple-patient cohorts utilizing a Bayesian design. Part A is designed to determine the recommended Phase 2 dose and schedule in up to 88 patients with allosteric human epidermal growth factor receptor 2 (HER2) or HER3 mutation; epidermal growth factor receptor (EGFR) or HER2 exon 20 insertion mutation; HER2 amplified or overexpressing tumor; or, EGFR exon 19 deletion or L858R mutation. Part B is a Phase 2, open-label, multicenter basket study designed to determine antitumor activity and safety in adult patients with solid tumors that have an allosteric HER2 mutation or EGFR or HER2 exon 20 insertion mutations using next-generation sequencing. This part will utilize a Simon 2-stage design and enroll up to 100 patients in four cohorts: 1) non-small cell lung cancer with EGFR or HER2 exon 20 insertion mutations; 2) breast cancer with an allosteric ErbB mutation; 3) solid tumors (except breast) with S310F/Y mutation; and, 4) other tumors harboring allosteric ErbB mutations not included in cohorts 1-3.

About BDTX-189

BDTX-189 is an orally available, irreversible small molecule inhibitor that is designed to block the function of an undrugged family of oncogenic proteins defined by driver mutations across a range of tumor types, and which affect both of the epidermal growth factor receptor (EGFR) and the tyrosine-protein kinase, ErbB-2, or human epidermal growth factor receptor 2 (HER2). These mutations include extracellular domain allosteric mutations of HER2, as well as EGFR and HER2 kinase domain exon 20 insertions, and additional activating oncogenic drivers of ErbB. The ErbB receptors are a group of receptor tyrosine kinases involved in key cellular functions, including cell growth and survival. BDTX-189 is also designed to spare normal, or wild type EGFR, which we believe has the potential to improve upon the toxicity profiles of current ErbB kinase inhibitors.