Xilio Therapeutics initiates Phase 2 trial for efarindodekin alfa, achieves $17.5M milestone.

Xilio Therapeutics announced the initiation of Phase 2 of a clinical trial for efarindodekin alfa (XTX301), a tumor-activated IL-12, in patients with advanced solid tumors. The trial achieved a $17.5 million development milestone under a license agreement with Gilead Sciences. The company also updated data from the ongoing Phase 1 trial, demonstrating promising anti-tumor activity. The milestone extends the anticipated cash runway into Q1 2027.

Xilio Therapeutics, Inc. (Nasdaq: XLO) has announced the initiation of Phase 2 of a clinical trial for efarindodekin alfa (XTX301), a tumor-activated IL-12, in patients with advanced solid tumors. The trial, which is part of an ongoing Phase 1/2 study, marks a significant milestone for the company as it extends its cash runway into the first quarter of 2027.

The Phase 2 trial aims to enroll approximately 40 patients at multiple sites in the United States, focusing on specific tumor types. The trial is designed to evaluate the safety and efficacy of efarindodekin alfa as a monotherapy in these patients. The company has already demonstrated promising anti-tumor activity in Phase 1, with two partial responses observed in late-line patients with advanced solid tumors.

The initiation of Phase 2 was accompanied by the achievement of a $17.5 million development milestone under Xilio's license agreement with Gilead Sciences, Inc. (Gilead). This milestone is part of a broader agreement that grants Gilead the right to develop and commercialize efarindodekin alfa, subject to certain conditions and payments.

Xilio's President and CEO, René Russo, Ph.D., stated, "We are pleased to announce the initiation of the Phase 2 clinical trial for efarindodekin alfa (XTX301), a tumor-activated IL-12, in patients with advanced solid tumors. The achievement of this important milestone highlights the promising Phase 1 data demonstrated for efarindodekin alfa to date, including two partial responses in late-line patients with advanced solid tumors and a generally well-tolerated safety profile."

Bernard Fine, Vice President of Oncology Early Development at Gilead, added, "We are encouraged by the totality of data observed to date for efarindodekin alfa (XTX301) as a monotherapy in patients with advanced solid tumors, and we are excited for the potential that IL-12 has to treat a broad range of tumor types."

As of June 30, 2025, Xilio had cash and cash equivalents of $121.6 million. The company anticipates that its current cash reserves, combined with the $17.5 million milestone, will be sufficient to fund its operating expenses and capital expenditure requirements through the first quarter of 2027.

Xilio expects to receive payment of the $17.5 million development milestone by the fourth quarter of 2025. The company is leveraging its proprietary platform to advance a pipeline of novel, tumor-activated I-O molecules designed to optimize the therapeutic index by localizing anti-tumor activity within the tumor microenvironment.

References:
[1] https://www.marketscreener.com/news/xilio-therapeutics-announces-initiation-of-phase-2-trial-for-efarindodekin-alfa-xtx301-a-tumor-ac-ce7d59dfde8bf522