A Phase 2, Safety and Efficacy Study of PRT3789 in Combination with Pembrolizumab in Patients with Advanced or Metastatic Solid Tumors with a SMARCA4 Mutation
Recipient organisationNIHR University College London Hospitals Biomedical Research Centre
NIHR supportRecorded as supported by this research centre
PeriodJan 2025 — Feb 2027
In plain English
AI plain-English summary
A new drug, PRT3789, is being tested in 60 patients across North America and Europe to see if it can safely break down faulty SMARCA4 proteins that help cancers grow. Mutations in the SMARCA4 gene are common across many cancer types, but no approved drug directly targets the faulty protein they produce. This trial combines PRT3789—which degrades the mutated protein, triggering cancer cell death—with pembrolizumab, an existing immunotherapy. The study has two parts: the first finds the safest dose of PRT3789, and the second tests that dose with pembrolizumab. Patients receive weekly infusions of PRT3789 plus pembrolizumab every three weeks, for up to 35 cycles over roughly two years. If the combination proves safe and effective, it could offer a new treatment option for patients with advanced or metastatic solid tumors carrying SMARCA4 mutations—a group currently lacking targeted therapies. Success would also validate a novel approach: using drugs that degrade specific mutant proteins rather than just inhibiting them, potentially opening a new class of cancer treatments. The trial is a direct step toward a practical therapy, not fundamental science.
View original technical description
Many cancer tumors share the same mutations in the DNA. Some of these mutations occur in a family of genes called SMARCA, and these genes are mutated in many types of human cancers. One of these SMARCA genes called SMARCA4 has instructions for the body to make SMARCA4 proteins, and when the gene is mutated, the instructions are faulty, and this fault may help cancers grow.The purpose of this study is to test a new drug called PRT3789 that is not approved by any regulatory authority. PRT3789 can target the mutated SMARCA proteins and cause them to break down, which can lead to cell death in the cancer cells. In this study, PRT3789 will be tested in combination with another approved drug called pembrolizumab. The goal of the study is to look at how safe and how effective PRT3789 is when combined with pembrolizumab.The study will recruit approximately 60 patients across various countries in North America and Europe, and will be divided into 2 parts:• Part 1 will look at the safest dose of PRT3789 and will require participants to have a weekly intravenous infusion of PRT3789 along with an intravenous infusion of pembrolizumab every 3 weeks.• Part 2 will use the dose of PRT3789 chosen from Part 1 and will have the same treatment schedule as Part 1.Participants will be in the study for approximately 2 years and will receive up to 35 cycles of study treatment. During the study, participants will have physical examinations, blood tests, urine tests, electrocardiograms (ECGs), CT/MRI scans and some will also have tumour biopsies.To be eligible, participants must be over 18, have certain SMARCA genes mutations and must have a specific type of advanced, recurrent or metastatic cancer.
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