Repare Therapeutics has reported initial proof of concept monotherapy data from the Phase I MYTHIC Module 1 trial of lunresertib (RP-6306) for the treatment of molecularly selected advanced solid tumours.

The first-in-human, international, open-label, dose-escalation study has evaluated the pharmacodynamics, safety, pharmacokinetics, and preliminary anti-tumour activity of lunresertib, an oral PKMYT1 inhibitor.

Till now it has enrolled a total of 63 patients and is still ongoing.

Repare chief medical officer Maria Koehler said: “These initial proof of concept results for lunresertib monotherapy show a favourable and distinct tolerability profile and preliminary antitumour activity that support our development plans for this programme.

“The data demonstrate that lunresertib effectively inhibits PKMYT1 and offers a synthetic lethal combination with CCNE1 amplification or inactivating mutations in FBXW7 and PPP2R1a.

“These findings, along with the continued advancement of the lunresertib programme across multiple ongoing combination clinical trials, validate our proprietary STEP2 platform and precision medicine approach.”

The Lunresertib programme also includes Module 2 which will evaluate lunresertib along with camonsertib (RP-3500/RG6526) in advanced solid tumours.

Two recommended doses of 240mg used daily and 80mg-100mg BID used intermittent weekly have been identified to be used in further combination studies.

Repare president and CEO Lloyd Segal said: “We look forward to reporting initial combination data of lunresertib with camonsertib, as well as lunresertib with gemcitabine, in the fourth quarter of this year, while also advancing multiple other trials to further our understanding of our first-in-class PKMYT1 inhibitor programme.”