Multiple clinical trial sites to be opened under collaboration with large network of community-based oncology practices

Acclaim-3 Study Supported by FDA Orphan Drug and Fast Track Designations

AUSTIN, Texas — (April 3, 2024) — 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 through its collaboration agreement with a large network of integrated, community-based oncology practices, the Company has added multiple clinical trial sites for its Acclaim-3 clinical study of Reqorsa Immunogene Therapy (quaratusugene ozeplasmid) in combination with Genentech's Tecentriq (atezolizumab) to treat patients with extensive-stage small cell lung cancer (ES-SCLC).

"With the majority of oncology patients treated by community-based oncology practices, this collaboration to expand our Acclaim-3 clinical study to additional trial sites is important as it may accelerate patient enrollment, provide access to our innovative clinical trial treatment for patients outside of major urban or academic settings, broaden the geographic reach of our study to more ES-SCLC patients in need and potentially benefit ES-SCLC patients who currently have limited benefit from existing treatment options," said Rodney Varner, President, Chairman and Chief Executive Officer at Genprex. "This collaboration leverages the broad network of oncologists and enables patients to access our promising treatment at the office of their primary oncologist, while allowing Genprex to more efficiently and expeditiously accelerate our Acclaim-3 clinical trial."

ES-SCLC is an aggressive form of lung cancer that is presently incurable. ES-SCLC has a median progression free survival (PFS) of 5.4 months from the start of initial therapy. However, once patients start receiving maintenance therapy with Tecentriq they have a median PFS of only 2.6 months. The combination of REQORSA and Tecentriq as maintenance therapy may provide a new therapeutic option for the treatment of small cell lung cancer (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, the Company's lead drug candidate, contains a plasmid that expresses TUSC2, a tumor suppressor gene protein. Nearly 100% of SCLCs have reduced or no TUSC2 protein expression, and 41% of SCLCs completely lack TUSC2 protein expression. Preclinical studies in mice support the hypothesis that re-expressing the TUSC2 protein may lead to improved clinical efficacy in combination with Tecentriq.

"We look forward to continuing our relationship with this large, nationwide network of oncology practices for our Acclaim-3 clinical trial in SCLC, which is the same partner we used for our Acclaim-1 clinical trial in NSCLC," said Mark Berger, M.D., Chief Medical Officer at Genprex. "Based on the success we experienced in patient enrollment from our other lung cancer clinical trial, we believe this collaboration will enhance our patient enrollment for Acclaim-3 and help us to expeditiously begin treating patients in need."

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 was initially expected to enroll up to 12 patients at three to five U.S. clinical sites, which has now doubled to approximately 10 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 25^th 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 the Acclaim-3 patient population. Additional information about the Acclaim-3 clinical trial can be found by visiting ClinicalTrials.gov.

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 Immunogene Therapy (quaratusugene ozeplasmid), is being evaluated in three clinical trials as a treatment for NSCLC and SCLC. Each of Genprex's three 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.

Interested investors and shareholders are encouraged to sign up for press releases and industry updates by visiting the Company Website, registering for Email Alerts and by following Genprex on Twitter, Facebook and LinkedIn.

Cautionary Language Concerning Forward-Looking Statements

Statements contained in this press release regarding matters that are not historical facts are "forward-looking statements" within the meaning of the Private Securities Litigation Reform Act of 1995. These forward-looking statements are made on the basis of the current beliefs, expectations and assumptions of management, are not guarantees of performance and are subject to significant risks and uncertainty. These forward-looking statements should, therefore, be considered in light of various important factors, including those set forth in Genprex's reports that it files from time to time with the Securities and Exchange Commission and which you should review, including those statements under "Item 1A – Risk Factors" in Genprex's Annual Report on Form 10-K for the year ended December 31, 2023.

Because forward-looking statements are subject to risks and uncertainties, actual results may differ materially from those expressed or implied by such forward-looking statements. Such statements include, but are not limited to, statements regarding: Genprex's ability to advance the clinical development, manufacturing and commercialization of its product candidates in accordance with projected timelines and specifications; the timing and success of Genprex's clinical trials and regulatory approvals; the effect of Genprex's product candidates, alone and in combination with other therapies, on cancer and diabetes; Genprex's future growth and financial status, including Genprex's ability to maintain compliance with the continued listing requirements of The Nasdaq Capital Market and to continue as a going concern and to obtain capital to meet its long-term liquidity needs on acceptable terms, or at all; Genprex's commercial and strategic partnerships, including those with its third party vendors, suppliers and manufacturers and their ability to successfully perform and scale up the manufacture of its product candidates; and Genprex's intellectual property and licenses.

These forward-looking statements should not be relied upon as predictions of future events and Genprex cannot assure you that the events or circumstances discussed or reflected in these statements will be achieved or will occur. If such forward-looking statements prove to be inaccurate, the inaccuracy may be material. You should not regard these statements as a representation or warranty by Genprex or any other person that Genprex will achieve its objectives and plans in any specified timeframe, or at all. You are cautioned not to place undue reliance on these forward-looking statements, which speak only as of the date of this press release. Genprex disclaims any obligation to publicly update or release any revisions to these forward-looking statements, whether as a result of new information, future events or otherwise, after the date of this press release or to reflect the occurrence of unanticipated events, except as required by law.

Genprex, Inc.

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