Russell, Jeffery Scott

TPS3171 Background: Genetic alterations in fibroblast growth factor receptors 2 and 3 ( FGFR2/3 ) occur in nearly all cancer types. FGFR2 fusions and rearrangements occur in up to 10-15% of intrahepatic cholangiocarcinomas (iCCA) and alterations in FGFR3 occur in 15-30% of urothelial cancers. The clinical benefit from currently approved FGFR inhibitors (FGFRi) is often curtailed by development of acquired resistance, which may arise through on-target mutations in the FGFR2/3 kinase domain. Additionally, off-tumor effects on FGFR1 by pan-FGFRi can lead to hyperphosphatemia and consequently to dose reductions or dose holds. Thus, there is an unmet clinical need for a selective FGFR2/3 inhibitor that has clinical efficacy against activating alterations and resistance mutations without causing FGFR1-mediated hyperphosphatemia. CGT4859 is an orally bioavailable, ATP-competitive, reversible inhibitor of FGFR2/3, with potency against clinically relevant FGFR2/3 kinase domain mutations. In addition, CGT4859 demonstrates >140 fold selectivity over FGFR1, and shows robust efficacy in target altered in vivo tumor models without increases in serum phosphorus. Nonclinical pharmacokinetics (PK) and safety data support evaluating CGT4859 in a first-in-human, open-label, dose-escalation and signal-seeking Phase I/II study (NCT06777316). Safety, tolerability, PK, pharmacodynamics, and antitumor activity of CGT4859 will be assessed in adults with histologically confirmed unresectable or metastatic iCCA or other solid tumors with FGFR2/3 alterations. Methods: CGT4859 will be administered orally continuously in 28-day cycles to patients (N=~50) at a starting dose of 1 mg QD, and dose escalation will not exceed 40 mg QD as determined using a Bayesian optimal interval design with backfill (BF-BOIN). This approach will be used to guide dose escalation and establish the maximum tolerated dose (MTD) and recommended Phase 2 Dose (RP2D). BF-BOIN enables backfilling of participants to doses that are cleared for safety during the dose escalation, generating additional data on safety and tolerability below the MTD. Objective response rate (ORR) and disease control rate will be determined based on investigator assessment using RECIST v1.1. Phase II will enroll up to 4 cohorts, each enrolling ~15 patients. Proposed cohorts will include participants who have iCCA and are either FGFRi-naïve or FGFRi-exposed. Two additional cohorts with other advanced solid tumors harboring FGFR2/3 alterations may be included based on signals detected in dose escalation. The primary efficacy endpoint for Phase II is ORR per RECIST v1.1. The preclinical data support the study of CGT4859 in this patient population with solid tumors harboring FGFR2 and/or FGFR3 genetic alterations. The phase I dose escalation study is currently enrolling at sites in the United States. Clinical trial information: NCT06777316 .

Abstract Background Esthesioneuroblastoma (ENB), also known as olfactory neuroblastoma, is a rare malignant neoplasm of the olfactory mucosa. Despite surgical resection combined with radiotherapy and adjuvant chemotherapy, ENB often relapses with rapid progression. Current multimodality, nontargeted therapy for relapsed ENB is of limited clinical benefit. Materials and Methods We queried whether comprehensive genomic profiling (CGP) of relapsed or refractory ENB can uncover genomic alterations (GA) that could identify potential targeted therapies for these patients. CGP was performed on formalin-fixed, paraffin-embedded sections from 41 consecutive clinical cases of ENBs using a hybrid-capture, adaptor ligation based next-generation sequencing assay to a mean coverage depth of 593X. The results were analyzed for base substitutions, insertions and deletions, select rearrangements, and copy number changes (amplifications and homozygous deletions). Results Clinically relevant GA (CRGA) were defined as GA linked to drugs on the market or under evaluation in clinical trials. A total of 28 ENBs harbored GA, with a mean of 1.5 GA per sample. Approximately half of the ENBs (21, 51%) featured at least one CRGA, with an average of 1 CRGA per sample. The most commonly altered gene was TP53 (17%), with GA in PIK3CA, NF1, CDKN2A, and CDKN2C occurring in 7% of samples. Conclusion We report comprehensive genomic profiles for 41 ENB tumors. CGP revealed potential new therapeutic targets, including targetable GA in the mTOR, CDK and growth factor signaling pathways, highlighting the clinical value of genomic profiling in ENB.