Neoadjuvant Pembrolizumab and Porustobart in Resectable pMMR/MSS Colon Cancer

Solstice Oncology, Inc.

Status and phase: Begins enrollment this month; Phase 2

Conditions: Proficient Mismatch Repair (pMMR) Colon Cancer; Microsatellite Stable (MSS) Colon Cancer; Colon Cancer

Treatments: Drug: Porustobart; Drug: Pembrolizumab

Study type: Interventional

Funder types: Industry

Identifiers

NCT07808151

SOL1-201

2026-527233-58-00 (EU Trial (CTIS) Number)

Details and patient eligibility

About

The goal of this clinical trial is to learn if giving two medicines together, porustobart and pembrolizumab, before surgery can treat a common type of colon cancer called microsatellite stable (MSS) colon cancer in adults. This type of cancer can be removed with surgery and has not spread to other parts of the body. Both medicines work by helping the immune system fight cancer.

The main questions this study wants to answer:

How well do the medicines destroy the cancer before surgery? What side effects do participants have when taking the medicines?

Researchers will compare two groups to see which treatment schedule works better and is safer. Both groups get pembrolizumab. One group gets one dose of porustobart (Day 1 only), and the other group gets two doses (Day 1 and Day 22).

Participants will:

Complete certain tests and procedures to make sure they are eligible Get the medicines through a vein on Day 1 and Day 22 then have surgery 6-9 weeks after starting treatment Return for checkups and tests every 6 months for up to 3 years after surgery

Enrollment: 100 estimated patients

Sex: All

Ages: 18+ years old

Volunteers: No Healthy Volunteers

Inclusion criteria

≥18 years of age at consent

Adenocarcinoma of the colon (rectosigmoid considered non-rectal); pMMR/MSS status

Any T3 or T4, N any, M0; disease amenable to surgical resection

ECOG Performance Status 0-1

Adequate tumor tissue sample with associated pathology report

Adequate hematologic, hepatic, and renal function

Reproductive status/contraception requirements per protocol

Exclusion criteria

Investigational agent within 3 weeks of first dose

Imminent or urgent need for surgery

Prior treatment with ICIs targeting CTLA-4, PD-1, or PD-L1

Systemic corticosteroid/immunosuppressive therapy within 1 week of first dose (exceptions apply)

History of severe hypersensitivity to a fully human mAb; interstitial lung disease; pneumonitis requiring corticosteroids

Active or history of autoimmune disease requiring systemic treatment within 2 years

Major surgery within 4 weeks of first dose; active infection requiring treatment

Trial design

Primary purpose: Treatment

Allocation: Randomized

Interventional model: Parallel Assignment

Masking: None (Open label)

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100 participants in 2 patient groups

Arm 1

Experimental group

Description:

Pembrolizumab IV every 3 weeks x 2 doses (Day 1, Day 22) plus porustobart x 1 dose (Day 1 only)

Treatment:

Drug: Porustobart

Drug: Pembrolizumab

Arm 2

Experimental group

Description:

Pembrolizumab IV every 3 weeks x 2 doses (Day 1, Day 22) plus porustobart every 3 weeks x 2 doses (Day 1, Day 22)

Treatment:

Drug: Porustobart

Drug: Pembrolizumab