Background
: SDH-deficient GIST is a rare disease with limited treatment options. The oncogenic mechanism of SDH deficiency has not been elucidated. Olverembatinib, already approved in China for the treatment of adult patients with TKI-resistant chronic-phase CML (CML-CP) or accelerated-phase CML (CML-AP), with or without the T315I mutation, has shown promising clinical efficacy in SDH-deficient GIST. This report provides the most updated Phase I efficacy data and translational data of olverembatinib in SDH-deficient GIST.
Methods
: This study (HQP1351-SJ0003; NCT03594422) was designed to evaluate the safety and efficacy of olverembatinib in patients (≥12 years of age) with GIST or other solid tumors. Olverembatinib was administered orally every other day (QOD). The study evaluated the clinical efficacy of olverembatinib and analyzed the drug’s MOA using multiple in vitro and in vivo assays including a SDHB knock-down rat pheochromocytoma PC12 (#5F7)-derived mouse xenograft model.
Patient enrollment
: As of March 12, 2024, a total of 26 patients with SDH-deficient GIST (confirmed by IHC) were treated with olverembatinib, including 25 (96.2%) who had received 1 to 4 TKIs and 13 (50.0%) who had received ≥3 TKIs.
Efficacy and Safety Results
: Olverembatinib was well tolerated at doses of 30 to 50 mg. In all, 6 (23.1%) patients achieved partial responses (PRs) and the median PFS was 22.0 months (range: 12.9-38.6).
Preclinical Results
: Olverembatinib had superior antiproliferative activity (vs. other approved TKIs) in SDHB-deficient cell lines (IC50, 0.129-5.132 μM). In PC12#5F7 (SDHB knock-down) cells, olverembatinib decreased HIF 2α, VEGFA, and FGFR1 protein levels and inhibited phosphorylation of FGFR1, IGF 1R, SRC, AKT, and ERK1/2. In PC12#5F7-derived xenograft models, olverembatinib demonstrated dose dependent antitumor activity at 10 and 20 mg/kg (QOD).
