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Advanced Solid TumorPhase 1/2NCT04896697

Vilastobart (XTX101) Monotherapy and Vilastobart and Atezolizumab Combination Therapy in Advanced Solid Tumors

A Phase 1/2 study testing vilastobart (XTX101) and Atezolizumab in people with Advanced Solid Tumor, run by Xilio Development, Inc. at 19 sites in United States.

Completed

Finished. The study has ended and is not enrolling. Results may be posted on the official record.

Official record
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Trial summary

This is a first-in-human, Phase 1/2, multicenter, open-label study designed to evaluate the safety and tolerability of vilastobart (XTX101) as monotherapy and vilastobart (XTX101) and atezolizumab combination therapy in patients with advanced solid tumors. Read more about this study

Who is it for?
Ages 18 years and older
Conditions the study is for
Advanced Solid Tumor
What is being tested?
vilastobart (XTX101) and Atezolizumab
Could I receive a placebo?
No, everyone receives an active treatment
How many people
125 participants
Where
19 sitesUnited States
Study dates
13 Sep 2021to 18 May 2026
Phase
Phase 1/2
Are there results?
None posted in the registry

Key requirements

Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.

  • Ages 18 years and older
  • All sexes
  • No healthy volunteers
  • Adult, Older adult

Who may be able to join

  • Disease Criteria -
  • Part 1A and 1C: Any histologically or cytologically confirmed solid tumor malignancy that is locally advanced or metastatic and has failed standard therapy, or standard therapy is not curative or available;
  • Part 1B:
  • Any histologically or cytologically confirmed solid tumor malignancy for which anti-PD-1 or anti-PD-L1 treatment is approved and has progressed on or after prior anti-PD-1 or anti-PD-L1 therapy.
  • Patients with metastatic castrate-resistant prostate cancer if they have progressed on at least 2 lines of systemic therapy
  • Patients with extensive stage small cell lung cancer (SCLC) after at least 1 line of prior therapy
Show all 13Show fewer
  • Patients with microsatellite stable colorectal cancer after at least 2 lines of prior therapy
  • Phase 2: Patients with histologically confirmed metastatic MSS CRC are eligible to enroll in Phase 2 as follows:
  • Patients must have had at least 1 prior chemotherapy regimen for metastatic CRC including all of the following agents: a fluoropyrimidine, irinotecan, oxaliplatin, bevacizumab or biosimilars, an anti epidermal growth factor receptor antibody (cetuximab or panitumumab), and v-raf murine sarcoma viral oncogene homolog B1 inhibitor/BRAF (encorafenib), if applicable
  • Patients with MSI-H/dMMR are excluded
  • ECOG performance status of 0 or 1
  • Adequate organ function
  • Part 1B, Part 1C, and Phase 2 only: measurable disease per iRECIST

Who cannot join

  • Received prior treatment with anti-CTLA-4 therapy
  • Received prior immune-checkpoint therapy and experienced Grade 3 or greater toxicity lasting greater than 6 weeks
  • Received prior approved systemic anticancer therapy within 4 weeks prior to study treatment
  • Received prior radiotherapy within 2 weeks prior to study treatment
  • Phase 2 only: Received prior anti-PD-1/L1 therapy or any investigational checkpoint inhibitory therapy
  • Has a diagnosis of immunodeficiency
Show all 12Show fewer
  • Has known malignancy (other than disease under study) that is progressing or has required active treatment within the past 3 years
  • Has an active autoimmune disease that has required systemic treatment in past 2 years, including the use of disease modifying agents, corticosteroids or immunosuppressive drugs
  • Has an active infection requiring systemic intravenous therapy within 4 weeks prior to study treatment, or oral therapy within 2 weeks prior to study treatment
  • Has a history of severe hypersensitivity reaction (≥ Grade 3) to any study intervention and/or any of its excipients
  • Has a known psychiatric or substance abuse disorder that would interfere with the participant's ability to cooperate with the requirements of the study
  • Phase 2 only: symptomatic bowel obstruction

Trial locations and contacts

19 sites in 1 country.

19 sites in 1 country

United States19 sites

  • Next Oncology

    Austin, Texas, 78758

  • Massachusetts General Hospital

    Boston, Massachusetts, 02114

  • Mary Crowley Cancer Research

    Dallas, Texas, 75230

  • City of Hope

    Duarte, California, 91010

  • Duke University Medical Center

    Durham, North Carolina, 27710

  • California Cancer Associates for Research and Excellence, cCARE

    Encinitas, California, 92024

  • NEXT Virginia

    Fairfax, Virginia, 22031

  • Carolina BioOncology Institute

    Huntersville, North Carolina, 28078

  • City of Hope-Lennar

    Irvine, California, 92618

  • Mayo Clinic Hospital

    Jacksonville, Florida, 32224

  • USC/Norris Comprehensive Cancer Center

    Los Angeles, California, 90033

  • Sarah Cannon Research Institute at Florida Cancer Specialists

    Orlando, Florida, 32827

  • Mayo Clinic Hospital

    Phoenix, Arizona, 85054

  • University of Pittsburgh Medical Center- Hillman Cancer Center

    Pittsburgh, Pennsylvania, 15232

  • Mayo Clinic Hospital

    Rochester, Minnesota, 55905

  • California Cancer Associates for Research and Excellence, cCARE

    San Marcos, California, 92069

  • UCLA Hematology/Oncology- Santa Monica

    Santa Monica, California, 90404

  • City of Hope-Upland

    Upland, California, 91786

  • Tranquil Clinical Research

    Webster, Texas, 77598

Other trials in United States

About this study

Official title: A First-in-Human, Multicenter, Phase 1/2, Open-Label Study of Vilastobart (XTX101) Monotherapy and Vilastobart (XTX101) and Atezolizumab Combination Therapy in Patients With Advanced Solid Tumors

This is a first-in-human, Phase 1/2, multicenter, open-label study designed to evaluate the safety and tolerability of vilastobart (XTX101) as monotherapy and vilastobart (XTX101) and atezolizumab combination therapy in patients with advanced solid tumors.

Read the detailed description

This is a first-in-human, Phase 1/2, multicenter, open-label study designed to evaluate the safety and tolerability of vilastobart (XTX101), a tumor-selective anti-CTLA-4 antibody, as monotherapy and vilastobart (XTX101) and atezolizumab combination therapy in patients with advanced solid tumors.

Part 1A will examine vilastobart (XTX101) monotherapy in an accelerated and standard 3+3 dose escalation design. Based on the results of Part 1A, patients with select advanced solid tumors will be enrolled in Part 1B, which will evaluate vilastobart (XTX101) monotherapy in relation to specific PD biomarkers.

Part 1C will examine vilastobart (XTX101) in combination with atezolizumab in a standard 3+3 dose escalation/dose de-escalation design. Part 1C may include a dose expansion cohort to further evaluate the safety, PK, and PD of dose levels that were previously cleared.

Phase 2 will examine vilastobart (XTX101) in combination with atezolizumab in patients with metastatic microsatellite stable colorectal cancer (MSS CRC) at the RP2D(s) defined in Part 1C.

Being tested
vilastobart (XTX101), Atezolizumab

What participants receive

What participants receive. In a randomised study each person is assigned to one group by chance.

  • vilastobart (XTX101)Drug

    vilastobart (XTX101) monotherapy

  • AtezolizumabDrug

    1200 mg administered every 3 weeks in combination with vilastobart (XTX101)

  • vilastobart (XTX101)Drug

    In combination with Atezolizumab

Study groups in NCT04896697
Study groupRoleWhat they receive
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).
Receives: Drug: vilastobart (XTX101)
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.
Receives: Drug: vilastobart (XTX101)
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).
Receives: Drug: Atezolizumab; Drug: 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.
Receives: Drug: Atezolizumab; Drug: vilastobart (XTX101)

What is being measured

The primary outcome is the main question the study is designed to answer.

  1. Incidence of Dose Limiting Toxicities (DLTs) in Part 1A

    Measured: Cycle 1 Day 1 up to just prior to the second dose of study drug at Cycle 2 day 1 (approximately 3 weeks)

  2. Incidence of Dose Limiting Toxicities (DLTs) in Part 1C

    Measured: Cycle 1 Day 1 up to Cycle 3 Day 1 (approximately 6 weeks)

  3. Incidence of treatment-emergent adverse events in Part 1

    Measured: Up to 24 months

  4. Incidence of changes in clinical laboratory abnormalities in Part 1

    Measured: Up to 24 months

  5. Investigator-assessed objective response rate (ORR) per iRECIST in Phase 2

    Measured: Up to 24 months

Secondary outcomes (17)

  1. Investigator-assessed objective response rate (ORR) per iRECIST in Part 1

    Measured: Up to 24 months

  2. Antidrug antibody (ADA) occurrence and titer in serum in Part 1

    Measured: Up to 24 months

  3. Plasma concentrations of vilastobart (XTX101) (total and intact) in Part 1 and Phase 2

    Measured: Up to 24 months

  4. Maximum observed plasma concentration (Cmax) in Part 1 and Phase 2

    Measured: Up to 24 months

  5. Time of maximum observed concentration (Tmax) in Part 1 and Phase 2

    Measured: Up to 24 months

  6. Trough concentrations (Ctrough) in Part 1 and Phase 2

    Measured: Up to 24 months

  7. Area under the curve (AUC) in Part 1 and Phase 2

    Measured: Up to 24 months

  8. Half-life (T1/2) in Part 1 and Phase 2

    Measured: Up to 24 months

  9. Systemic clearance (CL) in Part 1 and Phase 2

    Measured: Up to 24 months

  10. Volume of distribution (Vd) in Part 1 and Phase 2

    Measured: Up to 24 months

  11. Investigator-assessed ORR per RECIST in Phase 2

    Measured: Up to 24 months

  12. Duration of response per iRECIST in Phase 2

    The time from first documented confirmed response to first documented disease progression

    Measured: Up to 24 months

  13. Disease control rate in Phase 2

    The percent of patients who achieve complete response per iRECIST (iCR), partial response per iRECIST (iPR), or stable disease per iRECIST (iSD)

    Measured: Up to 24 months

  14. Progression-free survival per iRECIST in Phase 2

    The time from first dose to first documented disease progression or death

    Measured: Up to 24 months

  15. Overall survival in Phase 2

    The time from first dose to death due to any cause

    Measured: Up to 24 months

  16. Incidence of treatment-emergent AEs in Phase 2

    Measured: Up to 24 months

  17. Incidence of changes in clinical laboratory abnormalities in Phase 2

    Measured: Up to 24 months

Timeline

From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.

  1. First posted21 May 2021
  2. Study start13 Sep 2021
  3. Primary completion18 May 2026
  4. Study completion18 May 2026

Resources

More details

For doctors and researchers: how the study is designed, who runs it, and its registry IDs.

Study design
Study type
Interventional
Phase
Phase 1/2
Primary purpose
Treatment
Allocation
Non-randomised
Intervention model
Sequential
Masking
None (open label)
Enrolment
125 participants (actual)
IDs, dates and publications
ClinicalTrials.gov ID
NCT04896697
Sponsor's protocol ID
XTX101-01/02-001
Status last verified
Sep 2026
First submitted
6 May 2021
Last updated
10 Sep 2026
Results posted
No
Data monitoring committee
No
FDA-regulated drug
Yes
FDA-regulated device
No
Individual data sharing
No

Publications

  • Jenkins KA, Park M, Pederzoli-Ribeil M, Eskiocak U, Johnson P, Guzman W, McLaughlin M, Moore-Lai D, O'Toole C, Liu Z, Nicholson B, Flesch V, Qiu H, Clackson T, O'Hagan RC, Rodeck U, Karow M, O'Neil J, Williams JC. XTX101, a tumor-activated, Fc-enhanced anti-CTLA-4 monoclonal antibody, demonstrates tumor-growth inhibition and tumor-selective pharmacodynamics in mouse models of cancer. J Immunother Cancer. 2023 Dec 12;11(12):e007785. doi: 10.1136/jitc-2023-007785.

    PubMed 38164757

Questions about this trial

What is this clinical trial studying?

A Phase 1/2 study testing vilastobart (XTX101) and Atezolizumab in people with Advanced Solid Tumor, run by Xilio Development, Inc. at 19 sites in United States.

The full registered description is in the About this study section and the official record.

Who may be eligible to take part?

The sponsor lists 13 inclusion and 12 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.

Is this clinical trial currently recruiting?

The record says: finished, as of the sponsor's last update on 10 Sep 2026. Status can change between updates, so confirm with the study contact before making plans.

Where is the study taking place?

The record lists 19 sites in United States. Whether a site is taking part right now should be confirmed with that site. See every site.

What are the possible benefits and risks?

They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.

What does this combined phase mean?

Phase 1 studies test a treatment in a small group of people for the first time or in a new way, mainly to check safety and find the right dose.

Phase 2 studies give the treatment to a larger group to see whether it has the intended effect and to keep checking safety.

Not every study follows the same path, and some studies (observational studies, device studies) have no phase.

Are results available for this study?

The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.

How can a doctor refer a patient or contact the research team?

The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.

What does the primary outcome measure?

Incidence of Dose Limiting Toxicities (DLTs) in Part 1A (time frame: Cycle 1 Day 1 up to just prior to the second dose of study drug at Cycle 2 day 1 (approximately 3 weeks)). The study lists 5 primary outcomes in all. It is what the study was designed to measure, not a finding.

Where can I read the original study information?

On the ClinicalTrials.gov record for NCT04896697, which also lists 1 linked publication.

Does a listing mean the treatment is approved or proven to work?

No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.

How often is this information updated?

AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 10 Sep 2026.

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