Abstract CT119: A first-in-human phase 1 study of LOXO-435, a potent, highly isoform-selective FGFR3 inhibitor in advanced solid tumors with <i>FGFR3</i> alterations (trial in progress)
Bibliographic record
Abstract
Abstract Background: Alterations in the fibroblast growth factor receptor 3 (FGFR3) have been identified as oncogenic drivers in several solid tumor malignancies, including urothelial carcinoma (UC). Available pan-FGFR inhibitors target all 4 isoforms of FGFR (FGFR1 - 4) and consequently their efficacy can be limited by off-target toxicity (i.e. inhibition of other non-altered FGFR isoforms) including gastrointestinal, oral mucositis, and cutaneous/nail disorders, as well as FGFR1-mediated hyperphosphatemia. Moreover, clinical studies of pan-FGFR inhibitors have reported the development of drug resistance through acquired gatekeeper mutations (e.g. V555M and V565F) at the time of disease progression. LOXO-435 is a potent, highly isoform-selective FGFR3 inhibitor that is designed to preserve activity in the setting of gatekeeper resistance mutations. Preclinically, LOXO-435 has demonstrated potent in vitro and in vivo activity as a selective inhibitor of both wild-type and oncogenically activated FGFR3, including FGFR3 fusions, point mutations, and acquired gatekeeper resistance mutations without evidence of FGFR1-mediated hyperphosphatemia. Methods: LOXO-FG3-22001 is a multicenter, open-label, first-in-human phase 1a/b study of LOXO-435 in patients (pts) with FGFR3-altered advanced solid tumors, including metastatic UC (mUC) (NCT05614739). Eligible pts (≥ 18 years) must have an advanced or metastatic solid tumor with an FGFR3 alteration detected in tumor or ctDNA, ECOG PS of 0-1, and have received all standard therapy or have no known available options to provide benefit. The study will be conducted in 2 phases: phase 1a dose escalation and phase 1b dose expansion. Dose escalation (cohort A) will begin as a single-patient accelerated design, allowing intra-patient dose escalation, followed by the modified toxicity probability interval-2 method. Additional pts will be allowed to backfill to previously cleared dose levels that demonstrate therapeutically relevant exposures or direct evidence of clinical activity. Dose escalation will assess safety, PK/PD, and antitumor activity of LOXO-435 as monotherapy to determine the recommended phase 2 dose (RP2D). Dose expansion will include 4 cohorts of pts with prespecified activating FGFR3 alterations. Cohort B will enroll pts with mUC and include 2 cohorts to evaluate LOXO-435 as monotherapy (B1, B2) and 1 cohort to evaluate LOXO-435 in combination with pembrolizumab (B3). Cohort C will enroll pts with non-UC advanced solid tumors and will evaluate LOXO-435 as monotherapy (C1). Pts in cohort B1 must have progressed on or were intolerant to a prior FGFR inhibitor, and pts in cohorts B2, B3, and C1 must be FGFR inhibitor treatment naive. Dose expansion will evaluate the safety, PK/PD, and antitumor activity (per RECIST v1.1) of LOXO-435 at the RP2D. Citation Format: Gopa Iyer, Arlene Siefker-Radtke, Matthew Milowsky, Neal Shore, Xin Gao, Melissa A. Reimers, Noah Hahn, Rasha Cosman, Nobuaki Matsubara, Andrea Necchi, Debbie Robbrecht, Armelle Vinceneux, Enrique Grande, Jae-Lyun Lee, Tian Zhang, Tormod Guren, Ulrich M. Lauer, Michal Sarfaty, Bernhard Eigl, Syed Hussain, Xiang Zhao, Arjun V. Balar, Kaitlyn Francese, Ryan Widau, Benjamin Garmezy. A first-in-human phase 1 study of LOXO-435, a potent, highly isoform-selective FGFR3 inhibitor in advanced solid tumors with FGFR3 alterations (trial in progress) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 2 (Clinical Trials and Late-Breaking Research); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(8_Suppl):Abstract nr CT119.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.002 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".