NVL-330 is a selective, brain-penetrant inhibitor of oncogenic HER2 exon 20 insertion mutations in preclinical models

Background: HER2 exon 20 insertion mutations (exon20ins) are oncogenic driver mutations detected in 1∼3% of non-small cell lung cancer (NSCLC) patients in the US. Currently, there are no FDA- or EMA-approved targeted therapies for these patients. Development of small molecule inhibitors for HER2 exon20ins has been limited by off-target inhibition of closely related wild-type EGFR, which can lead to adverse events and dose-limiting toxicities including skin rash and gastrointestinal toxicity. In addition, activity in the central nervous system (CNS) is needed, since ∼20% of HER2 exon20ins NSCLC patients present with accompanying brain metastases at the time of diagnosis. Novel HER2 inhibitor NVL-330 was designed for coverage of HER2 exon20ins, selectivity over structurally related wild-type EGFR, and activity in the CNS. Material and Methods: NVL-330 was profiled using phospho-HER2 assays in NCI-H1781 cells (HER2 G776del insVC; HER2VC) and Ba/F3 cells overexpressing HER2 A775_G776 insYVMA (HER2YVMA), a phospho-EGFR assay in A431 cells (wild-type EGFR), and a viability assay in Ba/F3 HER2YVMA cells. Kinome profiling was conducted using the PhosphoSens® platform. Pharmacokinetic, pharmacodynamic, and efficacy studies were performed in mice subcutaneously implanted with NCI-H1781 cells or patient-derived xenograft (PDX) CTG-2543. Cellular efflux ratio was determined using an MDCK-hMDR1 permeability assay. The unbound brain-to-plasma partitioning ratio (Kp,uu) was determined at one hour after oral 10 mg/kg dosing in Wistar-Han rats and adjusted by fraction unbound. Results: NVL-330 inhibited cellular phosphorylation of HER2YVMA and HER2VC mutants, two major types of HER2 exon20ins, as well as the proliferation of Ba/F3 HER2YVMA cells, with IC50 values <20 nM. By comparison, NVL-330 modestly inhibited the phosphorylation of wild-type EGFR with IC50 >70-fold higher. In addition, NVL-330 was kinome selective; in a panel of 376 wild-type kinases, it did not inhibit any off-target kinases by >50% at 3 μM. in vivo, NVL-330 induced tumor regression at well-tolerated doses in an NSCLC PDX harboring HER2YVMA. NVL-330 also dose-dependently suppressed phospho-HER2 in xenograft tumors, supporting ontarget activity. Finally, NVL-330 demonstrated good brain penetration as evidenced by rodent Kp,uu, as well as a favorable efflux ratio. Conclusions: NVL-330 is a wild-type EGFR-sparing, brain-penetrant small-molecule inhibitor of HER2 exon20ins in preclinical models, demonstrating the potential to address a medical need for HER2 exon 20 insertion mutant NSCLC patients. Conflict of interest: Advisory Board: NEK is a scientific advisor of Nuvalent, Inc. Other Substantive Relationships: KLA, YS, BG, AT, SM, RAK, CMM, JCH and HEP are employees and stockholders of Nuvalent, Inc.