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US FDA grants Orphan Drug Designation to Genprex Reqorsa Immunogene Therapy for SCLC treatment

Genprex, Inc., a clinical-stage gene therapy company focused on developing life-changing therapies for patients with cancer and diabetes, announced the United States Food and Drug Administration (FDA) has granted Orphan Drug Designation (ODD) to the company’s lead drug candidate, Reqorsa Immunogene Therapy (quratusugene ozeplasmid), for the treatment of small cell lung cancer (SCLC).  

In addition to ODD for the treatment of SCLC, in June 2023, the FDA granted Fast Track Designation (FTD) for 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. With ES-SCLC, the cancer has spread from one lung to the other, or to other parts of the body. Extensive-stage is the most common type of SCLC. FDA has also granted Genprex FTD for two other indications of Reqorsa Immunogene Therapy, including Reqorsa in combination with Tagrisso for non-small cell lung cancer (NSCLC) in patients who have progressed after Tagrisso treatment, and Reqorsa in combination with Keytruda for NSCLC in patients who have progressed after Keytruda treatment.

“We are excited to receive Orphan Drug Designation from the FDA for Reqorsa for patients with SCLC,” said Rodney Varner, president, chairman and chief executive officer at Genprex. “This FDA Orphan Drug Designation in combination with our recently received FDA Fast Track designation underscores the great need for better treatment options for patients with SCLC, ES-SCLC and NSCLC.  We look forward to initiating the Acclaim-3 clinical trial expected in the fourth quarter of 2023 in order to bring hope of an effective new therapy to patients suffering with this life-limiting cancer.”

The FDA grants ODD status to investigational therapies being developed to treat, diagnose, or prevent a rare disease or condition affecting fewer than 200,000 people in the United States. Further, ODD provides benefits to drug developers, including assistance in the drug development process, tax credits for qualified trials, waiver of certain FDA fees, and potential for seven years of post-approval marketing exclusivity.

Genprex’s method of treating cancer is to reexpress tumour suppressor genes in cancers. Tumour suppressor genes are deleted or inactivated early in the process of cancer development. Reqorsa contains a plasmid that expresses a tumour suppressor gene protein called TUSC2. Virtually 100% of small cell lung cancers have reduced or no TUSC2 protein expression, and 41% completely lack TUSC2 protein expression. Pre-clinical studies in mice suggest that re-expressing the TUSC2 protein may lead to clinical efficacy. 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.

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 who did not develop tumor progression after receiving Tecentriq and chemotherapy as initial standard treatment.

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 US 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.

Genprex 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.