lirafugratinib (RLY-4008)

Pan-FGFR-selective inhibitors (erdafitinib, pemigatinib, and futibatinib) have been developed in clinical practice...FGFR2-selective inhibitor lirafugratinib, FGFR3-selective inhibitors LOXO-435 and TYRA-300, FGFR2/3-selective inhibitor ABSK061, and FGFR4-selective inhibitors are in clinical development. Additionally, novel isoform-selective FGFR-targeting degraders, FGFR2b/FGFR3-selective antibodies, and de novo-designed 'c' isoform-selective proteins provide novel treatment strategies. This review provides an overview of the current FGFR-targeted therapeutics and limitations and evaluates next-generation inhibitor development to guide future research.

P1/2, N=490, Active, not recruiting, Elevar Therapeutics | Trial primary completion date: Sep 2024 --> Sep 2025

P1/2, N=490, Active, not recruiting, Elevar Therapeutics | Trial completion date: Aug 2025 --> Dec 2027

P1/2, N=490, Active, not recruiting, Relay Therapeutics, Inc. | Trial completion date: Oct 2024 --> Aug 2025 | Trial primary completion date: Jun 2024 --> Sep 2024

At progression to FGFR inhibitors, FGFR2-driven malignancies are characterized by high intra- and inter-patient molecular heterogeneity, particularly in cholangiocarcinoma. Resistance to FGFR inhibitors can be overcome by sequential, molecularly-oriented treatment strategies across FGFR2-driven tumors.

P1/2, N=540, Active, not recruiting, Relay Therapeutics, Inc. | Recruiting --> Active, not recruiting

Various agents, including pan-FGFR inhibitors (erdafitinib and futibatinib), FGFR1/2/3 inhibitors (infigratinib and pemigatinib), as well as a range of more-specific agents, have been developed and several have entered clinical use. The next generation of small-molecule inhibitors, such as lirafugratinib and LOXO-435, and the FGFR2-specific antibody bemarituzumab are expected to have a reduced risk of hyperphosphataemia and the ability to overcome certain resistance mutations. In this Review, we describe the development and current clinical role of FGFR inhibitors and provide perspective on future research directions including expansion of the therapeutic indications for use of FGFR inhibitors, combination of these agents with immune-checkpoint inhibitors and the application of novel technologies, such as artificial intelligence.

Using this insight, we were able to design orthosteric binders that selectively and covalently engage the P-loop of FGFR2. Our drug discovery efforts culminated in the development of lirafugratinib (RLY-4008), a covalent inhibitor of FGFR2 that shows substantial selectivity over FGFR1 (~250-fold) and FGFR4 (~5,000-fold) in vitro, causes tumor regression in multiple FGFR2-altered human xenograft models, and was recently demonstrated to be efficacious in the clinic at doses that do not induce clinically significant hyperphosphatemia or diarrhea.

In vivo, RLY-4008 induces regression in multiple xenograft models - including models with FGFR2 resistance mutations that drive clinical progression on current pan-FGFRi - while sparing FGFR1 and FGFR4. In early clinical testing, RLY-4008 induced responses without clinically significant off-isoform FGFR toxicities, confirming the broad therapeutic potential of selective FGFR2 targeting.

These encouraging dose escalation data confirm the broad therapeutic potential of highly selective FGFR2 targeting with RLY-4008 by demonstrating encouraging initial efficacy across FGFR2-altered solid tumors and genomic alterations, with a differentiated safety profile that avoids FGFR1- and FGFR4-related toxicity. Phase 2 of ReFocus continues across solid tumors and with registrational intent in FGFRi-naïve, FGFR2 f/r CCA. Clinical trial information: NCT04526106.