Genprex Announces Positive Clinical Study Updates from Acclaim-1 and Acclaim-3 Phase 1/2 Clinical Trials in Lung Cancer

Demonstrates Prolonged Progression Free Survival of Two Patients in Acclaim-1 and Partial Remission from Maintenance Therapy in Acclaim-3

Re-focuses Oncology Clinical Development Program and Advances Work to Establish Biomarkers to Enrich Clinical Trial Patient Populations

AUSTIN, Texas, Aug. 14, 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 positive clinical study updates for its Acclaim-1 and Acclaim-3 clinical trials for the treatment of non-small cell lung cancer (NSCLC) and small cell lung cancer (SCLC), respectively, and plans to re-focus its oncology clinical development program.

Patients in the Company’s lung cancer clinical trials are being treated with the Company’s lead drug candidate, Reqorsa® (quaratusugene ozeplasmid) Gene Therapy. Two patients in the Acclaim-1 study have had prolonged Progression Free Survival (PFS) and importantly, the first treated patient in the Acclaim-3 study attained a Partial Remission (PR) from the start of maintenance therapy.

Ryan Confer, President and Chief Executive Officer of Genprex, commented on the update:
“We are excited by these early and promising patient responses to REQORSA treatment, particularly as these patients represent some of the most difficult to treat lung cancer patient populations. There is significant unmet medical need for patients afflicted with lung cancer, as nearly all patients’ disease progresses following treatment, even when treated with today’s most advanced targeted therapies and immunotherapies. This leaves patients with limited therapeutic options. We are thrilled our novel gene therapy treatment for lung cancer, REQORSA, is demonstrating early evidence of efficacy with a favorable safety profile. We look forward to continuing to evaluate REQORSA in our lung cancer clinical trials while we advance our efforts to bring new therapies to those battling cancer.”

Acclaim-1

The Acclaim-1 clinical trial is evaluating the combination of REQORSA and AstraZeneca’s Tagrisso® to treat patients with late-stage NSCLC who have activating EGFR mutations and disease progression after treatment with Tagrisso. The Acclaim-1 clinical trial has received an U.S. Food and Drug Administration (FDA) Fast Track Designation for late-stage NSCLC patients whose disease progressed after treatment with Tagrisso.

Two patients from the Phase 1 dose escalation portion of the study have had prolonged PFS and are still continuing to receive treatment on the study. One of them has received the treatment combination of REQORSA and Tagrisso for more than two years. This patient, who was previously treated with Tagrisso and chemotherapy and who continues to receive REQORSA and Tagrisso treatment, attained a PR after the second course of REQORSA and Tagrisso, and has maintained this response for more than two years. The second patient has had stable disease without disease progression for more than 15 months, and is also continuing to receive REQORSA and Tagrisso treatment.

Mark Berger, MD, Chief Medical Officer of Genprex, discussed the positive outcomes:
“We are very pleased with the positive early efficacy results for these patients. It is very compelling that one of the patients in our Acclaim-1 clinical trial has continued to see benefit from REQORSA treatment for more than two years and it’s been documented that the side effects of REQORSA have diminished, rather than increased, over time.”

The Phase 2a expansion portion of the study was designed to have two cohorts with 33 patients each. One cohort was for patients who have previously received only Tagrisso treatment, and one cohort was for patients who had previously received both Tagrisso treatment and chemotherapy. Based on resource prioritization and to focus on the patients for whom REQORSA is most likely to show a benefit, the Company has decided to limit its enrollment efforts moving forward to patients who received only prior Tagrisso treatment and to cease enrollment of the second cohort (patients who received prior Tagrisso treatment and chemotherapy). The Phase 2a expansion portion of the trial with one cohort is now expected to enroll approximately 33 patients. The Phase 2b randomized portion of the study, in which patients progressing on prior Tagrisso treatment will be randomized 1:1 to either REQORSA and Tagrisso combination therapy or to platinum-based chemotherapy, will remain unchanged.

Genprex will conduct an interim analysis following the treatment of 19 patients in the Phase 2a expansion portion who had previously received only Tagrisso treatment. The Company expects to complete the enrollment of the first 19 patients in the Phase 2a expansion portion of the study and conduct an interim analysis in the first half of 2025.

Acclaim-3

The Acclaim-3 clinical trial is evaluating the combination of REQORSA and Genentech’s Tecentriq® as a maintenance therapy to treat 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. The FDA has granted Fast Track Designation for the Acclaim-3 population of patients and has also granted Orphan Drug Designation for the treatment of SCLC.

In this study, patients receive maintenance therapy with REQORSA and Tecentriq until disease progression or unacceptable toxicity is experienced. Following completion of the Phase 1 dose escalation portion of the study, which the Company expects to complete during the second half of 2024, Genprex then expects to start the Phase 2 expansion portion of the study in the second half of 2024.

The first patient treated in the Phase 1 dose escalation portion of the Acclaim-3 clinical trial experienced an initial positive response after enrollment and dosing commenced in May. The patient had a PR, which is defined as at least a thirty percent (30%) decrease in tumor size, from the time the patient had a baseline CT scan after induction therapy and prior to the start of maintenance therapy, to the time of the CT scan performed after two cycles of maintenance therapy. 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, which suggests that REQORSA may be providing clinical benefit. A recent CT scan, performed after four cycles of maintenance therapy (three months), confirms 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 three months.

Dr. Berger commented on these compelling results:
“This patient’s response was not expected during maintenance therapy with Tecentriq alone, and we believe these results are promising and a positive early indication for the study. Once ES-SCLC patients begin maintenance therapy with Tecentriq, median PFS is very short; only 2.6 months, and further tumor regression rarely occurs. The ES-SCLC patient in the Acclaim-3 clinical trial treated with our combination therapy experienced PR, but asymptomatic disease progression was diagnosed by CT scan three months after the start of maintenance therapy. We find this positive result to be promising, particularly because this patient was treated with the lower of two doses planned for the Phase 1 portion of this clinical trial, and we are hopeful that the combination of REQORSA and Tecentriq will improve outcomes and help extend the lives of these very difficult to treat lung cancer patients.”

Genprex’s novel cancer treatment platform re-expresses tumor suppressor genes in cancers. Tumor suppressor genes are often deleted or inactivated early in the process of cancer development. The key component of REQORSA is a plasmid that expresses TUSC2, a tumor suppressor gene protein which plays a vital role in cancer suppression and normal cell metabolism. Nearly 100% of SCLCs have reduced or no TUSC2 protein expression, and 41% completely lack TUSC2 protein expression, thus restoring TUSC2 expression in SCLC has a strong biologic rationale. Nonclinical studies in mice support the hypothesis that re-expressing the TUSC2 protein in combination with Tecentriq may lead to improved clinical efficacy in SCLC.

Oncology Program Update

Mr. Confer and the executive team have evaluated resource allocations to ensure streamlined, focused strategies to support expeditious regulatory submissions for REQORSA and will implement the following changes to the Company’s oncology clinical development plans in order to prioritize resources and focus on the most promising aspects of the Acclaim-1 and Acclaim-3 lung cancer clinical trials.

• The Acclaim-2 clinical trial, a Phase 1/2 trial evaluating the combination of REQORSA and Merck & Co’s Keytruda® in patients with late-stage NSCLC whose disease has progressed after treatment with Keytruda, will cease enrollment of new NSCLC patients. Current patients in the Phase 1 dose escalation portion of the study will continue to be treated until disease progression. The Company made this decision based on a number of factors, including enrollment challenges and delays due to competition for eligible patients with numerous other trials involving the same patient population
• As described above, the Company will limit its enrollment efforts for the Phase 2a expansion portion of the Acclaim-1 study moving forward to patients who received only prior Tagrisso treatment and cease enrollment of the second cohort (patients who received prior Tagrisso treatment and chemotherapy). The Phase 2a expansion portion of the trial with one cohort is now expected to enroll approximately 33 patients. The Company continues to evaluate ways to optimize its clinical and research programs and operational strategies, as part of its ongoing prioritization initiative.

Commenting on the decision, Mr. Confer stated:
“The decision to discontinue the Acclaim-2 clinical trial is driven in part by the fact that there are hundreds of Keytruda combination lung cancer clinical trials, which made it difficult to recruit patients and investigators due to the volume of competing trials. We thank the clinicians and patients who participated in this study and look forward to potentially reviewing this patient population again at a future time, as we fully stand behind REQORSA’s potential to treat late-stage NSCLC patients whose disease progressed after treatment with Keytruda.”

Additionally, Genprex reports that the Company is collaborating with an academic research partner to discover, develop and utilize biomarkers to:

• select the patient population most likely to respond to REQORSA;
• predict and measure target engagement; and
• enable decisions on progression of the Company’s drug candidates to the next phase of development.

The Company’s academic research partner is currently analyzing biomarkers that would indicate lack of response in lung cancer that could enrich the Company’s population of responders in its clinical trials and enhance patient screening and enrollment in order to increase the likelihood of potential success of the Acclaim studies.

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 currently 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.

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