Genprex Completes Phase 1 Dose Escalation Portion of Acclaim-3 Clinical Trial

Results from Phase 1 Dose Escalation Demonstrate Favorable Safety Profile of REQORSA and Tecentriq in ES-SCLC Patients

AUSTIN, Texas , Dec. 16, 2024 /PRNewswire/ -- Genprex, Inc. ("Genprex" or the "Company") (NASDAQ: GNPX), a clinical-stage gene therapy company focused on developing life-changing therapies for patients with cancer and diabetes, today announced that it has completed the Phase 1 dose escalation portion of the Acclaim-3 clinical trial of Reqorsa Gene Therapy (quaratusugene ozeplasmid) in combination with Tecentriq (atezolizumab) as maintenance therapy to treat patients with extensive stage small cell lung cancer (ES-SCLC). In addition, the Safety Review Committee (SRC) has approved the opening of the Phase 2 expansion portion of the trial.

The combination of REQORSA and atezolizumab previously received U.S. Food and Drug Administration's (FDA) Fast Track Designation for the treatment of the Acclaim-3 patient population, and the FDA has also granted Orphan Drug Designation to REQORSA for the treatment of SCLC.

Based on full safety data, which showed no dose limiting toxicities (DLTs), the SRC determined that the Recommended Phase 2 Dose (RP2D) of REQORSA will be 0.12 mg/kg. This was the highest dose level delivered in the Phase 1 portion of the trial. The SRC also recommended the trial advance to the Phase 2 expansion portion of the study, which the Company has now opened for enrollment.

"We are pleased to complete the Phase 1 dose escalation portion of the Acclaim-3 clinical trial and to have now opened the Phase 2 expansion portion of Acclaim-3 for enrollment in the second half of 2024, in accordance with our previously disclosed guidance for timing and milestones," said Ryan Confer, President and Chief Executive Officer at Genprex. "Our partnership with a large network of community-based oncology practices has allowed us to have successful enrollment rates, enabling Genprex to meet our 2024 timeline targets for this study. In adding multiple clinical trial sites to our Acclaim-3 study, we have been able to more efficiently and expeditiously accelerate the Acclaim-3 clinical trial. Looking ahead, we believe this sets the stage for potential promising enrollment rates for the Phase 2 portion of the trial. Additionally, we will be submitting the results of the Phase 1 portion of the study to a clinical meeting and anticipate data presentation in 2025, and we remain encouraged by the early efficacy demonstrated in ES-SCLC patients."

Genprex previously reported the first patient treated in the Phase 1 dose escalation portion of the Acclaim-3 trial had a partial remission, which is defined as at least a thirty percent (30%) decrease in tumor size, from prior to the start of maintenance therapy to the time of the CT scan performed after two cycles of maintenance therapy. A CT scan performed after four cycles of maintenance therapy (three months), confirmed that the patient had a 30% decrease in tumor size in measurable lesions; however, one lesion not previously measurable had grown in size, thus leading to a conclusion of disease progression at that time. As the maintenance therapy consists of REQORSA and Tecentriq, and the patient had already received four cycles of Tecentriq during induction therapy and thus responses to Tecentriq would likely have occurred earlier, the Company believes this suggests that REQORSA may be providing clinical benefit.

In the Phase 1 dose escalation portion of the Acclaim-3 clinical trial, patients were treated with REQORSA and Tecentriq until disease progression or unacceptable toxicity was experienced. The primary endpoint of the Phase 1 escalation portion was to determine the Maximum Tolerated Dose (MTD) or RP2D.

The SRC is comprised of three physicians who are principal investigators in the trial. Based on the preliminary safety data from patients in the 0.12 mg/kg dose level, the SRC recommended that the 0.12 mg/kg dose be the RP2D that will be used in the Phase 2 portion of the trial and that the Phase 2 trial be opened for enrollment.

The Phase 1 dose escalation portion of the trial had two dose groups: 0.09 mg/kg and 0.12 mg/kg.The Phase 2 expansion portion will enroll approximately 50 patients at approximately 10 to 15 U.S sites. Patients will be treated with REQORSA and Tecentriq until disease progression or unacceptable toxicity is experienced. The primary endpoint of the Phase 2 portion is to determine the 18-week progression-free survival rate from the time of the start of maintenance therapy with REQORSA and Tecentriq 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.

Data presented at the October 2023 AACR-NCI-EORTC International Conference on Molecular Targets and Cancer Therapeutics from studies in humanized mouse models of SCLC that use human H841 cells have shown that the combination of REQORSA and Tecentriq provides significantly better control of tumor burden than either agent alone. The data from these studies also suggest that a combination treatment of REQORSA and Tecentriq can promote a significantly increased tumor cell killing effect in SCLC xenografts compared to that of Tecentriq alone.

About Acclaim-3
The Acclaim-3 clinical trial is an open-label, multi-center Phase 1/2 clinical trial evaluating the Company's lead drug candidate, Reqorsa Gene Therapy, in combination with Genentech, Inc.'s Tecentriq (atezolizumab) as maintenance therapy in patients with extensive stage small cell lung cancer (ES-SCLC) who did not develop tumor progression after receiving Tecentriq and chemotherapy as initial standard treatment.

About Genprex, Inc.
Genprex, Inc. is a clinical-stage gene therapy company focused on developing life-changing therapies for patients with cancer and diabetes. Genprex's technologies are designed to administer disease-fighting genes to provide new therapies for large patient populations with cancer and diabetes who currently have limited treatment options. Genprex works with world-class institutions and collaborators to develop drug candidates to further its pipeline of gene therapies in order to provide novel treatment approaches. Genprex's oncology program utilizes its systemic, non-viral Oncoprex Delivery System which encapsulates the gene-expressing plasmids using lipid-based nanoparticles in a lipoplex form. The resultant product is administered intravenously, where it is taken up by tumor cells that then express tumor suppressor proteins that were deficient in the tumor. The Company's lead product candidate, Reqorsa Gene Therapy (quaratusugene ozeplasmid), is being evaluated in two clinical trials as a treatment for NSCLC and SCLC. Each of Genprex's lung cancer clinical programs has received a Fast Track Designation from the FDA for the treatment of that patient population, and Genprex's SCLC program has received an FDA Orphan Drug Designation. Genprex's diabetes gene therapy approach is comprised of a novel infusion process that uses an AAV vector to deliver Pdx1 and MafA genes directly to the pancreas. In models of Type 1 diabetes, GPX-002 transforms alpha cells in the pancreas into functional beta-like cells, which can produce insulin but may be distinct enough from beta cells to evade the body's immune system. In a similar approach, GPX-002 for Type 2 diabetes, where autoimmunity is not at play, is believed to rejuvenate and replenish exhausted beta cells.