Genprex, Inc. announced that the FDA granted Fast Track Designation (FTD) for the Company's lead drug candidate, REQORSA® Immunogene Therapy, in combination with Genentech, Inc.'s Tecentriq® 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.
In the third quarter of 2023, Genprex expects to enroll the first patient in its Acclaim-3 clinical trial, which is a Phase 1/2 dose escalation and clinical response study of maintenance therapy evaluating REQORSA in combination with Tecentriq for this patient population. The Company has previously received two other FTDs for REQORSA, for REQORSA in combination with AstraZeneca PLC's Tagrisso® in patients with late-stage non-small cell lung cancer (NSCLC) whose disease progressed after treatment with Tagrisso, and for REQORSA in combination with Merck & Co's Keytruda® in patients with late-stage NSCLC whose disease progressed after treatment with Keytruda.
"We are very pleased to receive a third Fast Track Designation from the FDA for REQORSA, this time for patients with ES-SCLC in combination with the checkpoint inhibitor Tecentriq," said Rodney Varner, President, Chairman and Chief Executive Officer at Genprex. "This is another exciting achievement in our REQORSA development program, which further validates REQORSA's potential not only in NSCLC but also in SCLC. We look forward to accelerating the clinical development of REQORSA, and potentially providing a new treatment option for patients with SCLC."
Tumor suppressor genes are deleted or inactivated early in the process of cancer development. REQORSA contains a plasmid that expresses a tumor suppressor gene named TUSC2. Virtually 100% of small cell lung cancers express decreased amounts of TUSC2 tumor suppressor protein, and 41% completely lack TUSC2 protein expression. ES-SCLC has a very poor prognosis, with a median progression free survival (PFS) of only 5.2 months. Importantly, median PFS for patients receiving Tecentriq as maintenance therapy is only 2.6 months from the start of maintenance treatment, so there is a great need for improvement in maintenance therapy.
"This Fast Track Designation for the Acclaim-3 patient population is another validation of REQORSA's potential to treat lung cancer," said Mark Berger, MD, Chief Medical Officer at Genprex. "We are very excited to soon begin treating patients in the Acclaim-3 clinical trial, which positions REQORSA as a component of initial standard therapy for SCLC rather than as treatment for relapse. That will allow us to highlight the contribution of REQORSA to an earlier stage of treatment. Based on our experience in other REQORSA trials, we have reduced the Phase 1 portion of the study to two dose levels instead of the three dose levels in our Acclaim-1 and Acclaim-2 clinical trials. We believe this will shorten the Phase 1 portion of the trial. In addition, the median PFS of only 2.6 months seen with Tecentriq maintenance treatment will also shorten the time needed to evaluate the combination of REQORSA and Tecentriq as maintenance therapy for SCLC."
Patients in the Acclaim-3 clinical trial will be enrolled after receiving initial treatment with 3-4 cycles of carboplatin, etoposide, and Tecentriq, and achieving complete response, partial response or stable disease. They will then receive treatment with REQORSA and Tecentriq as maintenance therapy every 21 days until disease progression.
The Phase 1 dose escalation portion of the Acclaim-3 clinical trial is expected to enroll up to 12 patients at 3-5 U.S. clinical sites to determine the Maximum Tolerated Dose (MTD). If no dose limiting toxicities occur during Phase 1, then the highest dose evaluated will be the Recommended Phase 2 Dose. The Phase 2 portion of the study will then enroll approximately 50 patients at 5-10 sites. Patients will be treated with REQORSA and Tecentriq until disease progression or unacceptable toxicity is experienced.
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 in patients with ES-SCLC. Patients will also be followed for survival. A Phase 2 futility analysis will be performed after the 25th patient enrolled and treated reaches 18 weeks of follow up.
FDA may award FTD if it determines that non-clinical or clinical data demonstrate the potential for a drug to address an unmet medical need for a serious or life-threatening disease or condition. This provision is intended to facilitate development and expedite review of such drugs so that a product, if approved, can reach the market expeditiously.
FTD recipients may also be eligible for accelerated approval or rolling review of the recipient's Biologics License Application (BLA) if other qualifying criteria are met. In addition, Fast Track product candidates could be eligible for priority review if supported by clinical data at the time of BLA submission.
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