Evexta Bio S.A. has entered into a clinical collaboration and supply agreement with Roche to evaluate a combination therapy for patients with ER-positive (ER+), HER2-negative (HER2-), ESR1-mutated advanced or metastatic breast cancer. The collaboration will support a Phase 1b clinical study investigating Evexta Bio's lead investigational candidate, rupitasertib, in combination with Roche's investigational Selective Estrogen Receptor Degrader (SERD), giredestrant.

Under the agreement, Roche will provide giredestrant for the study, while Evexta Bio will sponsor and conduct the Phase 1b trial. The study will evaluate the safety, tolerability and preliminary anti-tumour activity of the combination therapy in patients with advanced or metastatic breast cancer carrying ESR1 mutations. The trial is expected to enrol at least 15 patients and is scheduled to begin in the fourth quarter of 2026.

Rupitasertib is an investigational first-in-class oral dual-node inhibitor targeting the PI3K/AKT/mTOR (PAM) signalling pathway. The therapy has been designed to selectively inhibit S6K and AKT1/3 while sparing AKT2, an approach intended to enhance anti-cancer activity while reducing the risk of treatment-related hyperglycaemia associated with conventional PAM pathway inhibitors.

The collaboration aims to explore the potential of an all-oral targeted treatment regimen for patients with ER+, HER2-, ESR1-mutated breast cancer, a subgroup that continues to face limited treatment options following disease progression.

Commenting on the collaboration, Dr. Shawn M. Leland, PharmD, RPh, Chairman of the Board at Evexta Bio, said the partnership marks the company's first clinical collaboration for rupitasertib and represents an important step in advancing innovative treatment options for patients with hormone receptor-positive breast cancer. He added that the combination of a first-in-class dual-node PAM pathway inhibitor with a SERD has the potential to address a significant unmet medical need.

The collaboration reflects the growing focus on precision oncology, where targeted therapies are being developed to improve outcomes for patients with genetically defined forms of cancer. If successful, the study could pave the way for further clinical development of the rupitasertib-giredestrant combination in advanced breast cancer.