On August 12, 2026 Xilio Therapeutics, Inc. (Nasdaq: XLO), a clinical-stage biotechnology company discovering and developing masked immuno-oncology therapies for people living with cancer, reported pipeline progress and business updates and reported financial results for the second quarter ended June 30, 2026.

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"In the second quarter, we remained focused on disciplined execution across our pipeline as we continued to advance our next generation of masked immuno-oncology therapies toward the clinic. Today, we are excited to announce FDA clearance of our IND for XTX501, a bispecific PD-1 / masked IL-2 that we believe has the potential to become a foundational backbone therapy for solid tumors," said René Russo, Pharm.D., president and chief executive officer of Xilio. "At the same time, we are advancing IND-enabling studies for our multi-specific, masked T cell engagers targeting CLDN18.2 and PSMA+STEAP1. Together, these programs highlight the potential to leverage our masking technology to unlock the next generation of sophisticated, multi-specific I-O therapies for people living with cancer."

Pipeline Progress and Business Updates

XTX501: bispecific PD-1 / masked IL-2

XTX501 is a novel bispecific PD-1 / masked IL-2 that has the potential to be a foundational backbone therapy for solid tumors, including in combination with other agents. XTX501 is designed to selectively stimulate PD-1 positive, antigen-experienced T cells and enhance their function while overcoming IL-2 receptor-mediated clearance, peripheral activity and tolerability issues associated with non-masked IL-2 agents.

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Xilio received clearance from the U.S. Food and Drug Administration (FDA) for the company’s investigational new drug application (IND) to proceed to a Phase 1/2 clinical trial for XTX501.
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Xilio expects to initiate dosing in the Phase 1 portion of the trial in patients with metastatic non-small cell lung cancer (NSCLC) and select advanced solid tumors in the second half of 2026. Xilio plans to report initial Phase 1 data in patients with metastatic NSCLC in the second half of 2027.

Masked T Cell Engager Programs

Xilio is leveraging its proprietary, clinically-validated masking technology and modular T cell engager (TCE) architectures to advance two wholly-owned masked TCE programs, as well as an additional masked TCE program in collaboration with AbbVie Group Holdings Limited (AbbVie).

The company’s masked TCEs are designed with a masked CD3 targeting domain and one or more tumor-associated antigen (TAA) binding domains as part of the core molecule design. In addition, the company’s modular architecture enables the incorporation of a co-stimulatory domain designed to further enhance potency and durability of T cell response, as well as the potential to mask the TAA binding domain(s) and/or mask the co-stimulatory signaling domain. Upon tumor-selective activation, Xilio’s TCE molecules are designed to release a potent, short half-life TCE in the tumor microenvironment.

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Xilio is advancing IND-enabling studies for a potential first-in-class masked TCE program targeting CLDN18.2 and a potential first-in-class multi-specific, masked TCE program targeting PSMA and STEAP1 with built-in co-stimulatory signaling. CLDN18.2 is a TAA expressed in gastrointestinal cancers (gastric, pancreatic and esophageal), and PSMA and STEAP1 are TAAs expressed in prostate cancer.
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Xilio plans to submit INDs for its CLDN18.2 and PSMA+STEAP1 programs in the second half of 2027.

Efarindodekin alfa: masked IL-12

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Xilio is evaluating efarindodekin alfa as a monotherapy in an ongoing Phase 2 clinical trial in patients with advanced solid tumors and expects to deliver an option data package to Gilead Sciences, Inc. (Gilead) in the first half of 2027.

Recent Corporate Updates

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Xilio appointed Ben Harshbarger as its chief legal officer in June 2026. Ben has over 20 years of executive leadership and legal expertise within the biopharmaceutical industry. Read more here.

Second Quarter 2026 Financial Results

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Cash Position: Cash and cash equivalents were $136.0 million as of June 30, 2026, compared to $137.5 million as of December 31, 2025.
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Collaboration and License Revenue: Collaboration and license revenue was $18.7 million for the quarter ended June 30, 2026, compared to $8.1 million for the quarter ended June 30, 2025. The increase was driven by an increase in collaboration and license revenue recognized under the collaboration and license agreements with AbbVie and Gilead.
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Research & Development (R&D) Expenses: R&D expenses were $14.6 million for the quarter ended June 30, 2026, compared to $15.3 million for the quarter ended June 30, 2025. The decrease was primarily driven by decreased clinical development activities related to vilastobart and decreased manufacturing activities for XTX501, partially offset by increased costs related to masked TCE programs and indirect research and development and increased personnel-related costs.
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General & Administrative (G&A) Expenses: G&A expenses were $7.6 million for the quarter ended June 30, 2026, compared to $7.1 million for the quarter ended June 30, 2025. The increase was primarily driven by an increase in personnel-related costs.
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Net Loss: Net loss was $6.4 million for the quarter ended June 30, 2026, compared to a net loss of $15.8 million for the quarter ended June 30, 2025.

Cash Runway

Based on its current operating plans, Xilio anticipates that its existing cash and cash equivalents will be sufficient to enable it to fund its operating expenses and capital expenditure requirements into the first quarter of 2028.

This estimate excludes up to $36.2 million in additional gross proceeds in the second half of 2026 if all outstanding Series C warrants are exercised at their current exercise price and any potential additional milestone payments, option-related fees or other contingent payments under Xilio’s collaboration and license agreements with AbbVie and Gilead, including up to $31.0 million in near-term milestones and option extension fees that could be achieved under the AbbVie collaboration through the first half of 2027.

About XTX501 and the Phase 1/2 Clinical Trial

XTX501 is an investigational bispecific PD-1 / masked IL-2 designed to selectively stimulate PD-1 positive, antigen-experienced T cells and enhance their function while overcoming IL-2 receptor-mediated clearance, peripheral activity and tolerability issues associated with non-masked IL-2 agents. Xilio is evaluating the safety and tolerability of XTX501 as a monotherapy in patients with metastatic non-small cell lung cancer (NSCLC) and select advanced solid tumors in the Phase 1 portion of a first-in-human, multi-center, open-label Phase 1/2 clinical trial at multiple sites in the United States. Please refer to NCT07688577 on www.clinicaltrials.gov for additional details.

(Press release, Xilio Therapeutics, AUG 12, 2026, View Source [SID1234670010])