Genprex, Inc. (?Genprex? or the ?Company?) announced that the first patient has been enrolled and dosed in the Company's Phase 1 dose escalation portion of the Acclaim-3 clinical study of Reqorsa® (quaratusugene ozeplasmid) Immunogene Therapy in combination with Genentech's Tecentriq® to treat patients with extensive-stage small cell lung cancer (ES-SCLC). Genprex has a novel cancer treatment platform that re-expresses tumor suppressor genes in cancers.

Tumor suppressor genes are often deleted or inactivated early in the process of cancer development. REQORSA contains a plasmid that expresses TUSC2, a tumor suppressor gene protein. Nearly 100% of SCLCs have reduced or no TUSC2 protein expression, and 41% completely lack TUSC2 protein expression.

Nonclinical studies in mice support the hypothesis that re-expressing the TUSC2 protein may lead to improved clinical efficacy in combination with Tecentriq. About the Acclaim-3 Clinical Trial: The Acclaim-3 clinical trial is a Phase 1/2 open-label, dose escalation and clinical response study of maintenance therapy evaluating REQORSA in combination with Tecentriq in patients with ES-SCLC. The Acclaim-3 clinical trial will enroll patients who did not develop tumor progression after receiving Tecentriq and chemotherapy as standard initial treatment, and who are therefore eligible for maintenance therapy.

The Phase 1 dose escalation portion of the Acclaim-3 clinical study is expected to enroll up to 12 patients at approximately ten U.S. clinical sites to determine the Maximum Tolerated Dose (MTD). If no dose limiting toxicities occur during the Phase 1 study, the highest dose evaluated will be the Recommended Phase 2 Dose. The Phase 2 portion of the study is expected to enroll approximately 50 patients at ten to fifteen U.S. sites.

Patients will be treated with REQORSA and Tecentriq until disease progression or unacceptable toxicity is experienced. Genprex expects to initiate the Phase 2 expansion study in the second half of 2024. The primary endpoint of the Phase 2 portion of the trial is to determine the 18-week progression-free survival rate from the time of the start of maintenance therapy with REQORSA and Tecentriq treatment in patients with ES-SCLC.

Patients will also be followed for survival. A Phase 2 futility analysis will be performed after the 25th patient enrolled and treated reaches 18 weeks of follow up. Genprex has received U.S. Food and Drug Administration (FDA) Ophran Drug and Fast Track designations for Reqorsa® Immunogene Therapy, in combination with Genentech, Inc.'s Tecentriq® in patients with ES-SCLC who did not develop tumor progression after receiving Tecentriq and chemotherapy as initial standard treatment.