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vilastobart

Phase 2

Pancreatic Cancer Metastatic | Small molecule | Oncology |Xilio Therapeutics, Inc.|Last Updated: Sep 10, 2026

Target and mechanism

Molecular targetCTLA-4
Target classProtein
ModalitySmall molecule

Also known as vilastobart (XTX101)

Success Probability

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Market & Valuation

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Trial Design

UNCONTROLLEDDMC
Total Trials1
Total Enrollment40

FDA Designations

No designations recorded

Clinical trial landscape

vilastobart · 2 trials · 2 indications

Phase 2 1Phase 1 1
NCT07765836Vilastobart+Retifanlimab in BRCA or PALB2 Deficient PCPancreatic Cancer Metastatic
NOT YET_RECRUITING40 Analytics
PHASE2NOT YET_RECRUITING
Vilastobart+Retifanlimab in BRCA or PALB2 Deficient PC
Pancreatic Cancer MetastaticUnlock trial analytics

Study Endpoints

Primary Endpoints

Objective response rate (ORR)
Up to 1 year from baseline.

The primary endpoint is objective response rate for combination of vilastobart with retifanlimab. Response is measured using RECISTv1.1 and evaluated independently. Evaluation of the primary endpoint will follow a Simon's two-stage design. The objective response rate will be reported with an exact binomial 95% confidence interval.

Incidence of Dose Limiting Toxicities (DLTs) in Part 1A
Cycle 1 Day 1 up to just prior to the second dose of study drug at Cycle 2 day 1 (approximately 3 weeks)
Incidence of Dose Limiting Toxicities (DLTs) in Part 1C
Cycle 1 Day 1 up to Cycle 3 Day 1 (approximately 6 weeks)
Incidence of treatment-emergent adverse events in Part 1
Up to 24 months
Incidence of changes in clinical laboratory abnormalities in Part 1
Up to 24 months
Investigator-assessed objective response rate (ORR) per iRECIST in Phase 2
Up to 24 months

Secondary Endpoints

Progression free survival (PFS)
From Day 1 through end of follow up (up to 3 years from registration)
Overall survival (OS)
Up to 3 years from registration
Duration of response (DoR)
From Day 1 through end of follow up (up to 3 years from registration)
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Study Design & Arms

AllocationNA
MaskingNONE
ModelSINGLE_GROUP
PurposeTREATMENT

Treatment Arms

ArmTypeDescription
Vilastobart + RetifanlimabEXPERIMENTALThis arm involves screening, study treatment with the study drugs, study visits, and follow-up visits for up to 3 years from time of joining study. Participants will receive up to 4 doses of Vilastobart, and Retifanlimab every three weeks until disease progression, intolerable side effects, or for a total of one year. Premedication for all vilastobart doses is required. For participants who experience disease progression on retifanlimab monotherapy or after completion of therapy on trial may be considered for re-induction with vilastobart and retifanlimab. Treatment beyond disease progression will be permitted for first instance of progressive disease by RECIST only if patients remain clinically stable from their disease and ongoing treatment is considered appropriate by patient, treating physician, and Sponsor Investigator.
Part 1A - vilastobart (XTX101) Monotherapy Dose EscalationEXPERIMENTALPart 1A Dose Escalation of vilastobart (XTX101) administered in ascending doses to patients with advanced or metastatic solid tumors to find the recommended phase 2 dose (RP2D).
Part 1B - Pharmacodynamic (PD) Dose ExpansionEXPERIMENTALPart 1B vilastobart (XTX101) at the RP2D will be administered to further examine vilastobart (XTX101) as monotherapy in patients with select advanced solid tumors.
Part 1C - vilastobart (XTX101) Dose Escalation and Dose Expansion in Combination with AtezolizumabEXPERIMENTALPart 1C will receive a labeled dose of atezolizumab in combination with vilastobart (XTX101).
Phase 2 - vilastobart (XTX101) Dose Expansion in Combination with AtezolizumabEXPERIMENTALPhase 2 will receive a labeled dose of atezolizumab in combination with vilastobart (XTX101) at the RP2D(s) in patients with MSS CRC.

Interventions

NameTypeDescription
vilastobart (XTX101)DRUG100mg administered once every 6 weeks (Day 1 of every 6-week cycle) by intravenous infusion (IV) over about 90-140 minutes. This will continue for up to 4 6-week cycles (4 doses).
RetifanlimabDRUG375 mg administered once every 3 weeks (Days 2 and 23 of every 6-week cycle) by intravenous infusion over about 30 minutes. This will continue for up to 12 months.
AtezolizumabDRUG1200 mg administered every 3 weeks in combination with vilastobart (XTX101)
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Eligibility Criteria

Age Range18 Years to N/A
SexALL
Healthy VolunteersNo
Study Sites1

Inclusion Criteria: * Participant must have histologically proven metastatic pancreatic cancer. Histologies including acinar cell carcinoma, carcinoma, ductal carcinoma, ductal adenocarcinoma, poorly differentiated or adenosquamous carcinoma are allowed. * Participant must have a germline or somati...

Countries:United States
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Competitive Landscape -Pancreatic Cancer 177 trials (matched to "Pancreatic Cancer Metastatic")

Recent Changes (Last 90 Days)

LOWAug 14, 2026NCT07765836NEW_TRIAL: changed
LOWAug 14, 2026NCT07765836NEW_TRIAL: changed
MEDIUMJul 17, 2026NCT04896697TRIAL_REMOVED: changed
MEDIUMJul 17, 2026NCT04896697TRIAL_REMOVED: changed
MEDIUMJul 17, 2026NCT04896697TRIAL_REMOVED: changed

Frequently asked questions about vilastobart

What is vilastobart used for?

Vilastobart is an investigational oncology drug being studied for the treatment of advanced solid tumors and metastatic pancreatic cancer. It is currently in clinical development for these indications.

What does vilastobart target?

Vilastobart targets CTLA-4, a protein involved in regulating immune responses. By targeting CTLA-4, vilastobart is designed to modulate the immune system's ability to fight cancer cells.

Who makes vilastobart?

Vilastobart is being developed by Xilio Therapeutics, Inc., a biopharmaceutical company. Xilio Therapeutics is publicly traded under the ticker symbol XLO.

What phase is vilastobart in?

Vilastobart is in Phase 1 clinical development. It is an investigational drug and has not been approved by regulatory authorities for any use.

What clinical trials is vilastobart in?

Vilastobart has been studied in a Phase 1 trial (NCT04896697) for advanced solid tumors, which has been completed. A Phase 2 trial (NCT07765836) is planned for metastatic pancreatic cancer in patients with BRCA or PALB2 deficiencies.

Is vilastobart the same as XTX101?

Yes, vilastobart is also known as XTX101. Both names refer to the same investigational drug being developed by Xilio Therapeutics.