Exhibit 99.1
Xilio Announces Initial Monotherapy Safety and Anti-Tumor Activity Data for XTX202, a Tumor-Activated, Engineered, Beta-Gamma IL-2, in Late Line Patients with Advanced Solid Tumors
Initial evidence of dose-dependent disease control rate with 50% disease control rate at higher doses (≥2.8 mg/kg) and 31% disease control rate across all dose levels in a range of solid tumor types, including cold tumors
Treatment-related adverse events primarily Grade 1-2 at doses up to 4 mg/kg administered once every three weeks in outpatient setting, with no reported signs or symptoms of vascular leak syndrome
Two patients continuing treatment for more than 1 year, demonstrating XTX202 was well-tolerated with repeated, long-term dosing
Plan to evaluate XTX202 as a monotherapy in ongoing Phase 2 proof-of-concept trial at 4.0 mg/kg in patients with advanced melanoma and renal cell carcinoma
Xilio Therapeutics to host investor conference call and webcast on Monday, November 6, 2023 at 8:00 a.m. ET
WALTHAM, Mass., November 3, 2023 – Xilio Therapeutics, Inc. (Nasdaq: XLO), a clinical-stage biotechnology company discovering and developing tumor-activated immuno-oncology therapies for people living with cancer, today announced initial safety, pharmacokinetic (PK), pharmacodynamic (PD) and anti-tumor activity data from its ongoing Phase 1/2 clinical trial evaluating XTX202, an investigational tumor-activated, engineered, beta-gamma IL-2, in late line patients with advanced solid tumors. The data were presented at the Society for Immunotherapy of Cancer (SITC) 38th Annual Meeting in San Diego, CA being held on November 1-5, 2023.
“The newly reported data from our Phase 1/2 clinical trial for XTX202 expands the evidence across our programs supporting clinical validation of our tumor-activated technology. We observed a disease control rate of 50% at higher doses (≥2.8 mg/kg) and 31% across all dose levels in a variety of advanced and IO refractory solid tumors, including cold tumors. Importantly, treatment-related adverse events were primarily Grade 1-2 with no evidence of vascular leak syndrome reported at any dose level, and two patients are continuing on treatment for more than one year, highlighting XTX202’s potential for long-term tolerability at high doses,” said Katarina Luptakova, M.D., chief medical officer of Xilio. “In addition, an analysis of an on-treatment biopsy from a patient receiving 2.8 mg/kg of XTX202 demonstrated evidence of activation in the tumor with minimal active drug in peripheral circulation and also suggests that monotherapy doses at or above 2.8 mg/kg are approaching the optimal range to engage CD8+ T effector cell and NK cell expansion while continuing to avoid stimulation of regulatory T cells. Overall, these encouraging data support continued evaluation of XTX202 at a dose of 4.0 mg/kg in our Phase 2 trial of patients with metastatic renal cell carcinoma and unresectable or metastatic melanoma and the exploration of opportunities for combination therapy.”
Investigator Dr. Howard Kaufman, M.D., FACS of Massachusetts General Hospital commented, “As opposed to the trademark toxicities associated with recombinant IL-2, the preliminary data from the XTX202 Phase 1/2 clinical trial demonstrate a marked difference in tolerability and the potential for long-term treatment at high doses for XTX202 that has not been possible previously with systemically active IL-2 molecules. These data showcase the importance of concentrating potent IO molecules directly in the tumor microenvironment and offer an encouraging signal for continued investigation of XTX202 monotherapy at high doses along with its broad combination potential with other mechanisms of action where the stimulation of CD8+ T cells and NK cells without expansion of regulatory T cells would be synergistic.”
Data from the Ongoing Phase 1/2 Clinical Trial for XTX202
As of a data cutoff date of October 26, 2023, 62 patients with advanced solid tumors had been administered XTX202 in an outpatient setting. Fifty-four (54) patients were treated in Phase 1 monotherapy dose-escalation and dose-expansion at seven dose levels ranging from 0.27 mg/kg to 4 mg/kg administered once every three weeks (Q3W). Eight (8) patients were treated in Phase 2 monotherapy at a dose level of 1.4 mg/kg Q3W.
Patients enrolled in Phase 1 were heavily pre-treated, with 74% of patients previously treated with three or more lines of anti-cancer therapy and 69% of patients previously treated with an immunotherapy. All patients in Phase 2 had been previously treated with an immunotherapy. As of the data cutoff date, 20 patients were continuing treatment with XTX202 across the Phase 1/2 trial.