Molecular profiling firm Foundation Medicine partnered with Relay Therapeutics to develop FoundationOne CDx as a companion diagnostic for RLY-4008, the company’s investigational FGFR2 inhibitor.

FoundationOne CDx is an in vitro diagnostic tool that can identify substitutions, insertion and deletion alterations (indels), and copy number alterations (CNAs) in 324 genes.

RLY-4008 is a selective oral small molecule inhibitor of FGFR2, which is being tested for treatment in patients with cholangiocarcinoma (CCA), bile duct cancer, and other solid tumours that have FGFR2 mutations.

The FGFR family, a group of closely related proteins with very comparable protein sequences and characteristics, consists of four members, of which FGFR2 is one.

FoundationOne CDx would be used to find individuals with FGFR2 fusions and pick rearrangements in CCA suitable for treatment with RLY-4008 if the medicine and companion diagnostic is authorised.

Relay Therapeutics R&D president Don Bergstrom said: “FGFR2-mutated cholangiocarcinoma is an aggressive condition that’s generally diagnosed in advanced stages when the prognosis is poor and treatment options are limited.

“We’re proud to partner with the leader in companion diagnostic approvals as we work to advance this potentially life-changing therapy and create access to it once approved.”

Relay presented interim clinical data for RLY-4008 from this patient population in pan-FGFR inhibitor nave patients which demonstrated an 88% overall response rate.

The company expects to fully enrol this pivotal cohort in the second half of 2023.

Foundation Medicine’s range of FDA-approved genomic profile assays can help physicians to identify genetic changes that support individualised therapy recommendations.

FoundationOne CDx and FoundationOne Liquid CDx are companion diagnostics that help oncologists pinpoint patients who could benefit from FDA-approved targeted treatments.

FoundationOne Liquid CDx is a qualitative next-generation sequencing-based in vitro diagnostic test for prescription use only to analyse 324 genes using circulating cell-free DNA (cfDNA).