Xilio Therapeutics Announces Initiation of Enrollment for Phase 1 Combination Trial of XTX101, a Tumor-Activated, Fc-Enhanced Anti-CTLA-4, and Updated Phase 1 Monotherapy Data
Phase 1 combination dose escalation expected to support planned Phase 2 trial in microsatellite stable colorectal cancer (MSS CRC)
Updated Phase 1 monotherapy data for XTX101 at the recommended Phase 2 dose (RP2D) continues to demonstrate minimal treatment-related adverse events, consistent with tumor-activated molecule design, and a 33% disease control rate across a range of late-line and IO refractory advanced solid tumors
Previously reported confirmed partial response with XTX101 monotherapy in patient with advanced PD-L1 negative NSCLC continued through 36 weeks, including complete resolution of liver metastases
WALTHAM, Mass., December 7, 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 the initiation of enrollment for its Phase 1 clinical trial of XTX101, an investigational tumor-activated, Fc-enhanced anti-CTLA-4, in combination with atezolizumab and reported updated monotherapy data from its ongoing Phase 1 clinical trial evaluating XTX101 in late-line patients with advanced and immuno-oncology (IO) refractory solid tumors. The data were presented at the European Society for Medical Oncology (ESMO) Immuno-Oncology Congress on December 7, 2023.
“With the recent initiation of Phase 1 dose escalation for XTX101 in combination with atezolizumab, we look forward to establishing a recommended Phase 2 dose in support of our plans to evaluate the combination in a Phase 2 trial in patients with microsatellite stable colorectal cancer (MSS CRC), including patients with liver metastases where there is an especially significant unmet need,” said Katarina Luptakova, M.D., chief medical officer of Xilio. “The new Phase 1 data we reported for XTX101, which include 18 patients treated at the recommended Phase 2 dose of 150 mg Q6W, continue to demonstrate XTX101’s promising safety profile with primarily Grade 1 or 2 treatment-related adverse events. In addition to the previously reported confirmed partial response in a non-small cell lung cancer patient through 36 weeks, these new data also suggest further evidence of monotherapy anti-tumor activity in late-line and IO refractory patients at the recommended Phase 2 dose.”
Updated Data from the Ongoing Phase 1 Clinical Trial for XTX101
As of the data cutoff date of November 13, 2023, 36 patients with advanced solid tumors had been administered XTX101 monotherapy, including 18 patients at the recommended Phase 2 dose and schedule (RP2D) of 150 mg once every six weeks (Q6W).
Patients treated at the RP2D of 150 mg Q6W were heavily pre-treated, with 83% of patients receiving three or more lines of anti-cancer therapy and 56% previously treated with an immunotherapy.
Preliminary Safety Data
At the RP2D of 150 mg Q6W, 18 patients (including 9 patients previously reported) were evaluable for safety as of the data cutoff date:
| ● | Safety data were consistent with previously reported results. XTX101 monotherapy was generally well-tolerated with treatment-related adverse events (TRAE) primarily Grade 1 or 2, and no patients discontinued treatment due to a TRAE. In addition, as previously reported, only one patient had a dose reduction due to an adverse event. |
| ● | The most common TRAE of any grade (≥10% incidence) reported by investigators was fatigue (11%). |
| ● | As previously reported, investigators reported only two Grade 3 TRAEs: Grade 3 TRAE of diarrhea, which occurred after two doses and resolved after five days without steroid use, and one Grade 3 TRAE of dermatitis. |
In addition, as previously reported, no Grade 4 or 5 TRAEs were reported by investigators across all dosing levels and dosing intervals.