On November 10, 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 third quarter ended September 30, 2026.

Schedule your 30 min Free 1stOncology Demo!
Discover why more than 1,500 members use 1stOncology™ to excel in:

Early/Late Stage Pipeline Development - Target Scouting - Clinical Biomarkers - Indication Selection & Expansion - BD&L Contacts - Conference Reports - Combinatorial Drug Settings - Companion Diagnostics - Drug Repositioning - First-in-class Analysis - Competitive Analysis - Deals & Licensing

                  Schedule Your 30 min Free Demo!

"In the third quarter, we initiated our Phase 1/2 clinical trial for XTX501, a PD-1/masked IL-2 bispecific that we believe has the potential to become a foundational backbone immunotherapy regimen for solid tumors," said René Russo, Pharm.D., president and chief executive officer of Xilio. "By incorporating masking and tumor-selective activation of a high potency, alpha-optimized IL-2 with inhibition of PD-1/PD-L1 in a single molecule, XTX501 is designed to simultaneously leverage these two validated mechanisms, while overcoming the toxicity and rapid clearance that have limited non-masked IL-2 therapies. We also continued to execute across our preclinical pipeline, advancing our programs for masked, multi-specific TCEs with built-in co-stimulation toward planned IND filings next year."

Pipeline Progress and Business Updates

XTX501: PD-1/masked IL-2 bispecific

XTX501 is a novel, investigational PD-1/masked IL-2 (alpha-optimized) bispecific antibody fusion protein that combines two complementary mechanisms in a single molecule: selective inhibition of the PD-1/PD-L1 pathway and potent IL-2-driven expansion of T cells. The PD-1 binding arm is designed to selectively direct IL-2 activity to PD-1 positive, antigen-experienced T cells and enhance their function. The IL-2 binding arm incorporates a masked, high potency IL-2 variant with an alpha-optimized receptor binding profile. By leveraging Xilio’s proprietary masking technology, XTX501 aims to overcome IL-2 receptor-mediated clearance, peripheral activity and tolerability challenges associated with non-masked IL-2 therapies.

•
Xilio recently dosed the first patient in the Phase 1 portion of the trial for XTX501 in patients with metastatic non-small cell lung cancer (NSCLC) and select advanced solid tumors. For more information, read the press release here.
•
Xilio recently presented a trial-in-progress poster highlighting the design of the Phase 1/2 clinical trial of XTX501 at the Society for Immunotherapy of Cancer (SITC) (Free SITC Whitepaper) 41st Annual Meeting.
•
Xilio plans to report initial Phase 1 data in patients with metastatic NSCLC in the fourth quarter of 2027.

Masked T Cell Engager (TCE) Programs

As part of the core design, Xilio’s TCEs incorporate a masked CD3 binding domain, a tumor-associated antigen (TAA) binding domain and built-in co-stimulation. The company’s modular architecture enables the flexibility to incorporate additional TAA binding domains and mask the TAA binding domain(s) and/or co-stimulatory signaling domain. Upon tumor-selective activation, the molecules are designed to release the mask(s) and deliver a potent TCE with a short half-life in the tumor microenvironment.

XTX602: dual-masked CLDN18.2-targeting multi-specific TCE with co-stimulation

XTX602 is a potential first-in-class, dual-masked CLDN18.2-targeting multi-specific TCE with built-in CD2 co-stimulation. CLDN18.2 is a TAA expressed in gastrointestinal cancers (gastric, pancreatic and esophageal). By incorporating masks for both the CLDN18.2 and the CD3 binding domains, XTX602 is designed to overcome potential gastrointestinal toxicity associated with non-masked CLDN18.2-targeting molecules. In addition, the CD2 co-stimulatory domain is built directly into the molecule to enable enhanced T cell activation, expansion and durability of T cell response.

•
Investigational new drug application (IND)-enabling studies for XTX602 are ongoing, and Xilio plans to submit an IND for XTX602 in the fourth quarter of 2027.

XTX701: masked PSMAxSTEAP1-targeting multi-specific TCE with co-stimulation

XTX701 is a potential first-in-class, masked PSMAxSTEAP1-targeting multi-specific TCE with built-in CD2 co-stimulation. PSMA and STEAP1 are TAAs collectively expressed in approximately 95% of metastatic castration-resistant prostate cancer. Targeting these two TAAs is intended to address heterogeneity of expression of PSMA and STEAP1 across prostate tumors and limit resistance and lack of durability of response due to antigen escape. By incorporating a mask for the CD3 binding domain, XTX701 is designed to minimize toxicity due to peripheral T cell activation and on-target, off-tumor engagement associated with non-masked molecules. In addition, the CD2 co-stimulatory domain is built directly into the molecule to enable enhanced T cell activation, expansion and durability of T cell response.

•
IND-enabling studies for XTX701 are ongoing, and Xilio plans to submit an IND for XTX701 in the fourth quarter of 2027.

Efarindodekin alfa: masked IL-12

•
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

•
Xilio appointed Yariv Houvras, M.D., Ph.D., as its chief medical officer in September 2026. Dr. Houvras has over 20 years of executive leadership across premier industry and academic research institutions in clinical development, translational medicine and immuno-oncology. Read more here.

Third Quarter 2026 Financial Results

•
Cash Position: Cash and cash equivalents were $122.2 million as of September 30, 2026, compared to $137.5 million as of December 31, 2025.
•
Collaboration and License Revenue: Collaboration and license revenue was $10.0 million for the quarter ended September 30, 2026, compared to $19.1 million for the quarter ended September 30,

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

2025. The decrease was driven by a decrease in collaboration and license revenue recognized under the company’s collaboration and license agreements with AbbVie and Gilead.
•
Research & Development (R&D) Expenses: R&D expenses were $14.8 million for the quarter ended September 30, 2026, compared to $14.3 million for the quarter ended September 30, 2025. The increase was primarily driven by an increase in preclinical research and development activities related to the company’s wholly-owned masked TCE programs, an increase in clinical trial startup activities related to the company’s Phase 1/2 clinical trial for XTX501 and an increase in personnel-related costs due to higher research and development headcount, partially offset by a decrease in preclinical development activities and manufacturing activities related to IND-enabling studies for XTX501 and a decrease in clinical development activities for efarindodekin alfa and vilastobart.
•
General & Administrative (G&A) Expenses: G&A expenses were $6.9 million for the quarter ended September 30, 2026, compared to $6.7 million for the quarter ended September 30, 2025. The increase was primarily driven by an increase in stock-based compensation expense.
•
Net Loss: Net loss was $5.9 million for the quarter ended September 30, 2026, compared to a net loss of $16.3 million for the quarter ended September 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 fourth quarter 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.

(Press release, Xilio Therapeutics, NOV 10, 2026, View Source [SID1234674572])