IDEAYA Biosciences has dosed the first patient in the Phase l trial examining IDE161 (NCT 05787587) to treat patients having tumours with homologous recombination deficiency (HRD).

The patient was dosed at The University of Texas MD Anderson Cancer Center in Houston, US.

The trial will investigate the safety, tolerability, pharmacokinetic and pharmacodynamic properties along with preliminary efficacy of IDE161 as monotherapy in the targeted patients.

Its clinical protocol includes dose escalation in solid tumours with HRD. 

Based on the selection of an expansion dose, IDEAYA expects to increase the cohorts of patients with HRD tumours in breast cancer, ovarian cancer and other solid tumours. 

The breast cancer cohort of the trial will concentrate on estrogen receptor positive (ER+), human epidermal growth factor receptor 2 negative (Her2-) tumours with HRD, which account for around 10% to 14% of breast cancer patients.

The University of Texas MD Anderson Cancer Center Investigational Cancer Therapeutics associate professor Dr Timothy Yap is a leading principal investigator of the trial.

IDE161 is a potent, selective, small-molecule PARG inhibitor.

IDEAYA Biosciences chief medical officer Dr Darrin Beaupre said: “We believe IDE161 may be impactful for ER+ / Her2- breast cancer patients with HRD, as well as for patients having ovarian cancer and other solid tumours with HRD, for whom current treatment options are limited.

“Based on its preclinical tolerability profile, IDE161 may also be suitable for evaluation with several distinct classes of combination agents, providing multiple paths to demonstrate patient benefit in these populations.”