Expects to Initiate the Phase 2 Expansion Study in the Second Half of 2024

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

AUSTIN, Texas — (May 14, 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 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).

"We are excited to take this next step in our fight against lung cancers as we work to advance an innovative therapy that we believe provides hope to patients suffering with ES-SCLC, an especially aggressive form of lung cancer that has extremely limited treatment options," said Ryan Confer, President and Chief Executive Officer at Genprex. "With a median progression free survival (PFS) of 5.2 months, ES-SCLC has a particularly poor prognosis. Additionally, patients receiving Tecentriq as maintenance therapy have a median PFS of 2.6 months after the start of maintenance therapy. With such limited benefit from current treatments, we believe the combination of REQORSA and Tecentriq can provide a promising new therapeutic option for the treatment of small cell lung cancer."

"The Phase 1 dose escalation portion of the Acclaim-3 study is expected to determine the maximum tolerated dose for the Phase 2 expansion study," stated Mark Berger, M.D., Chief Medical Officer of Genprex. "The favorable results from our Phase 1 Acclaim-1 study in non-small cell lung cancer (NSCLC) enabled us to shorten the Phase 1 portion of Acclaim-3. This should allow us to complete the Phase 1 portion of the study during the second half of 2024 and to advance more quickly into the Phase 2 expansion portion of Acclaim-3 in the second half of 2024. We look forward to providing study updates as we advance this potentially life-saving therapy to benefit patients battling 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 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 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. Additional information about the Acclaim-3 clinical trial can be found by visiting ClinicalTrials.gov.

About Reqorsa Immunogene Therapy
Reqorsa (quaratusugene ozeplasmid) Immunogene Therapy for NSCLC and SCLC consists of the TUSC2 gene expressing plasmid encapsulated in non-viral nanoparticles made from lipid-based molecules in a lipoplex form (Genprex's Oncoprex Delivery System) with a positive electrical charge. REQORSA is injected intravenously and specifically targets cancer cells, which generally have a negative electrical charge. REQORSA is designed to deliver the functioning TUSC2 gene to cancer cells while minimizing their uptake by normal tissue. REQORSA has a multimodal mechanism of action whereby it interrupts cell signaling pathways that cause replication and proliferation of cancer cells, re-establishes pathways for programmed cell death, or apoptosis, in cancer cells, and modulates the immune response against cancer cells. In addition, REQORSA disrupts the metabolism of cancer cells by decreasing glycolysis and ATP production in cancer cells with decreased TUSC2.

Genprex's strategy is to develop REQORSA in combination with currently approved therapies and believes that REQORSA's unique attributes position it to provide treatments that improve on current therapies for patients with NSCLC, SCLC, and possibly other cancers.

Tecentriq is a registered trademark of Genentech, Inc.

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 (quaratusugene ozeplasmid) Immunogene Therapy, 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.

(877) 774-GNPX (4679)

GNPX Investor Relations

[email protected]

GNPX Media Contact

Kalyn Dabbs

[email protected]