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Genprex Partners With Roche to Validate TROP2 Testing, Seeking Patient-Stratification Clues for Lung Cancer Gene Therapy
The collaboration advances preliminary TROP2 and PTEN signals toward assay validation, with the aim of establishing patient-selection criteria for Reqorsa clinical trials; however, the existing associations still require confirmation with prospective clinical data.
Precision treatment of non-small cell lung cancer depends not only on whether a drug can work, but also on whether the patients most likely to benefit can be identified in advance. Genprex and Roche Diagnostics have begun biomarker assay validation, preparing to translate early research signals involving TROP2 and PTEN into a potential patient-screening tool for the Reqorsa gene therapy clinical program.
According to a Genprex announcement and documents filed with the U.S. Securities and Exchange Commission, Roche will validate the assay using its own TROP2 antibody, with results expected around the end of 2026. If the assay performs well enough to support clinical use, Genprex plans to incorporate it into non-small cell lung cancer studies, including the patient-selection strategy for the Acclaim-1 trial; any integration remains contingent on the validation results.
The collaboration stems from biomarker analyses previously announced by Genprex. The company said that, in preclinical models, lung cancer cells with higher TROP2 protein expression and lower PTEN expression responded better to Reqorsa, which carries the TUSC2 tumor-suppressor gene. A separate preliminary clinical association indicated that patients with a TROP2 H-score above 100 and a PTEN H-score below 100 had longer progression-free survival. The H-score is a tissue-scoring method that combines staining intensity with the proportion of positive cells, but whether these thresholds can consistently distinguish patients who benefit has not been confirmed in prospective trials.
According to financial news reports, the validation will involve Roche’s EPR20043 antibody. This antibody is also associated with the VENTANA TROP2 RxDx computational pathology system, which has received Breakthrough Device Designation from the U.S. Food and Drug Administration. The system uses digital image analysis to help quantify TROP2 expression in tumor tissue. The specific purpose of this collaboration is to test whether the assay can be reliably reproduced, not to demonstrate that artificial intelligence itself can predict the efficacy of Reqorsa.
Background
PTEN is an important tumor-suppressor protein that inhibits cell-growth signaling, and related tests are already used to stratify patients for some cancer treatments. TROP2 is a cell-surface protein commonly found in multiple epithelial cancers and is also an important target for antibody-drug conjugates. Genprex is attempting to use the two in combination, hoping that a pattern of high expression of one and low expression of the other can identify tumors more likely to respond to TUSC2 gene therapy.
The current evidence still has clear limitations: the announcement did not disclose the number of validation samples, the tissue sources, or prespecified performance criteria, nor did it provide randomized controlled data sufficient to determine clinical benefit. Even if technical validation is completed by year-end, it will still be necessary to show that the testing thresholds can be reproduced across laboratories and genuinely improve patient selection in prospective clinical trials. Whether regulators will accept the test as the basis for a companion diagnostic also remains unresolved.