CTNI-11. A PHASE 1 OPEN-LABEL STUDY OF BRAF INHIBITOR ABM-1310 IN PATIENTS (PTS) WITH RECURRENT BRAF V600-MUTATED PRIMARY CNS TUMORS

Abstract BACKGROUND ABM-1310 is a blood-brain barrier penetrant BRAF inhibitor. Here we report interim results from our phase 1 study of ABM-1310. METHODS This is a dose-escalation plus expansions trial for adult pts with BRAF V600-mutated primary CNS tumors. In the dose-escalation, ABM-1310 is given at 150 or 200 mg twice a day (bid). In the expansion, ABM-1310 150 mg bid is administered. Study objectives include patient safety, maximum tolerated dose (MTD), preliminary efficacy and pharmacokinetics (PK). Clinical trial information: NCT05892653. RESULTS By May 6, 2024, 15 pts (7 male; median age 39 years old) have been treated. In the dose escalation: 4 pts received ABM-1310 150 mg bid, and another 7-pts received ABM-1310 200 mg bid. In the expansion, all 4 pts were given ABM-1310 at 150 mg bid. Among 14 efficacy evaluable pts, 3 had partial response (PR) (including one each of glioblastoma, WHO grade 2 and 3 pleomorphic xanthoastrocytoma) and 9 pts had stable disease as their best responses. Two pts have PR response for > 8 months and continue study treatment. All pts experienced treatment-related AEs. Common AEs were asymptomatic QT prolongation (n=11) and rash (n=10). Seven pts had grade 3 QT prolongation. There was no drug-related SAE. There was no ABM-1310 related dose limiting toxicity although a few pts had study treatment interruption or dose reduction. One patient discontinued prematurely due to asymptomatic Grade 3 QT prolongation. There were no drug-related deaths. The MTD for ABM-1310 was 200 mg bid, the recommended dose was 150 mg bid. In PK assessment, ABM-1310 drug exposure vs. dosage showed a linear proportional relationship. This trial is ongoing. CONCLUSIONS ABM-1310 was generally safe and tolerated. There were no new safety signals. Preliminary efficacy data demonstrate favorable anti-cancer activity in patients with recurrent BRAF V600-mutated primary CNS tumors.