Positive Clinical Data on Biomarkers in Patients Receiving Reqorsa® Gene Therapy Published at the 2026 ASCO Annual Meeting

Trop-2 H-scores Above 100 and PTEN H-scores Below 100 Correlated With Longer Progression Free Survival in Non-Small Cell Lung Cancer Patients

Identified Biomarkers May Predict Patient Response, Enable Targeted Patient Selection and Allow for Precision Medicine

AUSTIN, Texas, May 26, 2026 /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 its research collaborators' abstract was published at the 2026 American Society of Clinical Oncology (ASCO) Annual Meeting. The abstract details positive clinical data from studies of predictive biomarkers in patients receiving its lead drug candidate, Reqorsa® Gene Therapy (quaratusugene ozeplasmid), for the treatment of lung cancer.

"This clinical validation, derived from patients in our Acclaim clinical trials, substantiates earlier preclinical evidence revealing that Non-Small Cell Lung Cancer (NSCLC) patients receiving REQORSA who exhibit high Trop-2 levels and low PTEN levels experience prolonged Progression Free Survival (PFS), underscoring the critical role these biomarkers play in predicting treatment efficacy and advancing our understanding of this novel gene therapy," said Ryan Confer, President and Chief Executive Officer at Genprex. "These findings represent a substantial leap forward for personalized medicine in lung cancer, allowing for a targeted approach to potentially improve treatment outcomes and optimize resource allocation within the therapeutic landscape."

The featured Genprex-supported abstract at ASCO 2026:

Title: "Predictive biomarkers for PFS in patients receiving quaratusugene ozeplasmid"
Abstract Number: e15184

Quaratusugene ozeplasmid is a gene therapy that delivers a plasmid coding for the TUSC2 tumor suppressor gene to lung cancer cells, as >80% of lung cancers have been shown to have decreased or absent TUSC2 protein.  TUSC2 protein levels have not correlated with PFS, presumably because of the complexities of TUSC2 protein regulation. Preclinical studies have identified higher levels of Trop-2 protein in organoids and lower levels of PTEN protein in lung cancer cell lines as correlating with response (AACR 2026). Tumor tissue from patients in clinical trials with quaratusugene ozeplasmid were evaluated for Trop-2 and PTEN protein expression.

Monoclonal antibodies against Trop-2 (BSB148 from BioSB) and PTEN (138G6 from Cell Signaling Technology) were used for immunohistochemistry in paraffin sections from archival tumor samples in patients enrolled in three clinical trials with quaratusugene ozeplasmid and results expressed as H-scores. H-scores were calculated  by evaluating diaminobenzidine staining intensity using the formula [1 × (% cells 1+) + 2 × (% cells 2+) + 3 × (% cells 3+)].

Data on Trop-2 and PTEN protein expression and data on PFS were available from 18 patients enrolled in clinical trials with quaratusugene ozeplasmid.

• Six patients with NSCLC were enrolled in the Acclaim-1 trial in combination with osimertinib.
• One patient was enrolled in the Acclaim-2 trial in combination with pembrolizumab.
• Eleven patients with small cell lung cancer (SCLC) were enrolled in the Acclaim-3 trial in combination with atezolizumab.
• In patients with NSCLC, Trop-2 H-scores above 100 correlated with prolonged PFS (p=0.05), and PTEN H-scores below 100 correlated with prolonged PFS (p=0.03).
• In patients with SCLC, Trop-2 H-scores were universally low, and thus non-evaluable. PTEN H-scores in patients with SCLC did not correlate with prolonged PFS (p=0.53).

Following up on preclinical cell line and organoid models indicating that Trop-2 and PTEN protein expression correlated with response, levels of Trop-2 and PTEN protein were evaluated in patients treated with quaratusugene ozeplasmid. In conclusion, both Trop-2 H-scores above 100 and PTEN H-scores below 100 correlated with longer PFS in patients with NSCLC, but not in patients with SCLC.

Beyond the ASCO 2026 Abstract:

Following the clinical studies outlined above, Genprex completed additional analysis to evaluate the relationship between NSCLCs with high intensity staining (3+) and PFS. NSCLCs with 3+ Trop-2 staining had a strong relationship with PFS that was just outside the bounds for significance (p=0.053) and those with 3+ PTEN staining exhibited a trend for a negative relationship with PFS that was not statistically significant (p=0.309).  These results are consistent with the H-score analysis regarding a strong positive relationship between Trop-2 expression and PFS. High (3+) Trop-2 expression will be investigated further as a potential biomarker for REQORSA.

"We look forward to additional studies using intensity staining to understand the correlation between Trop-2 expression and PFS, offering more concrete data for optimized patient selection," said Mark S. Berger, Chief Medical Officer at Genprex.

About Acclaim-1
The Acclaim-1 clinical trial is an open-label, multi-center Phase 1/2 clinical trial evaluating REQORSA in combination with AstraZeneca's Tagrisso® (osimertinib) in patients with late-stage NSCLC with activating epidermal growth factor receptor (EGFR) mutations whose disease progressed after treatment with Tagrisso or or Tagrisso-containing regimens. Acclaim-1 received Fast Track Designation by the U.S. Food and Drug Administration (FDA) for use of REQORSA in combination with TKI Tagrisso for the treatment of NSCLC patients with EGFR mutations whose tumors progressed after treatment with Tagrisso.

About Acclaim-3
The Acclaim-3 clinical trial is an open-label, multi-center Phase 1/2 clinical trial evaluating REQORSA 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. Acclaim-3 received Fast Track Designation by the FDA for the Acclaim-3 treatment combination of REQORSA and Tecentriq as maintenance therapy in patients with ES-SCLC who did not develop tumor progression after receiving Tecentriq and chemotherapy as initial standard treatment. The FDA also granted Orphan Drug Designation to REQORSA for the treatment of SCLC.

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 for Type 2 diabetes, where autoimmunity is not at play, GPX-002 is believed to rejuvenate and replenish exhausted beta cells.

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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, 2025.

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, its intended regulatory submissions and any resulting regulatory approvals; the effect of Genprex's product candidates, alone and in combination with other therapies, on cancer and diabetes, including allowing for a targeted approach to potentially improve treatment outcomes and optimize resource allocation within the therapeutic landscape and High (3+) Trop-2 expression as a potential biomarker for REQORSA; 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; Genprex's intellectual property and licenses; and Genprex's current expectations, estimates, forecasts and projections about the industry and markets in which it operates.

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.

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