New hope may be on the horizon for sufferers of Recurrent Respiratory Papillomatosis, or RRP, a rare and debilitating disease that typically requires patients to undergo multiple surgeries each year to remove benign tumors called papillomas, that grow in the respiratory tract.
Precigen, Inc. PGEN released complete data at a virtual R&D Day event on January 24, 2023 at 4:30 PM ET from a robust, open label Phase 1 trial of its investigational candidate PRGN-2012, an innovative gene-based immunotherapy designed to inhibit or prevent the growth of the dreaded papillomas in the hopes of reducing the number of surgeries.
Clinical data presented showed a strong response in RRP patients with 50% of patients in complete response, requiring no post-treatment surgeries, following PRGN-2012 treatment at Dose Level 2. All complete responders remained surgery-free post-treatment with a minimum 12-months of follow up. PRGN-2012 treatment at Dose Level 2 significantly reduced the need for surgeries in severe, aggressive RRP patients with the median number of surgeries in 12-month period being reduced from 6.5 pre-treatment to 0.5 post-treatment. The data also showed that PRGN-2012 was very well tolerated by patients, with no dose-limiting toxicities or treatment-related adverse events above Grade 2.
A Phase 2 trial of PRGN-2012 in RRP is also underway and, depending on the results, it may qualify as a pivotal trial to facilitate the filing of a Biologics License Applications (BLA). It is approximately 85 percent enrolled to date.
RRP affects both children and adults. Symptoms include a hoarse voice, difficulty sleeping and swallowing, chronic coughing, and breathing problems. In extreme cases, the disease can be fatal because the papillomas cause severe airway obstruction to the lungs and the lungs become flooded with fluids and infection. In a minority of patients RRP can malignantly transform into cancer.
The company estimates indicate there are up to 16,000 active cases of RRP in the US and as many as 75,000 total worldwide, although there are believed to be thousands more undiagnosed cases. No therapeutic treatments are currently approved by the FDA. Company estimates suggest PRGN-2012 could have peak annual US sales of approximately $1 billion if approved.
There is a high need for safe and effective therapeutic options for RRP. Currently, the only standard-of-care treatment for RRP is repeat surgeries to maintain voice and respiratory function. The sad reality is that many RRP patients require hundreds of surgeries over their lifetimes. The quality of life and economic burden of recurrent surgeries on patients, their families and physicians is very high.
The surgeries are only effective at removing the built-up Human Papillomavirus Virus (HPV)-infected lesions in the respiratory tract, but they do not prevent further buildup. Patients often struggle to maintain consistent employment because of the frequent surgeries all while incurring costly medical bills.
Moreover, frequent surgeries for RRP can worsen a patient’s condition overtime by potentially increasing the spread of the HPV virus and the likelihood of serious co-morbidities, including breathing issues and loss of vocal function.
PRGN-2012 Seen as Promising, Potentially Less Costly Solution
Lacking other treatments to potentially reduce the frequency of surgeries, some physicians have turned to off-label use of drugs approved for other indications, but without proven benefit for RRP patients.
One such drug is cidofovir, a broad-spectrum antiviral drug from Gilead (GILD) and Pfizer (PFE) that was originally approved for treating CMV and HIV infection. It is prescribed by some physicians treating RRP, but it can cause liver toxicity and patients typically rebound after withdrawal, making it –at best– a short-term solution.
Another is Avastin® from Roche Holdings (RHHBY), an antiangiogenic drug in wide use as a cancer therapy. Avastin has been shown to temporarily slowdown papilloma growth in some RRP patients. However, it can cause severe side effects and cannot activate specific T cells needed to eliminate HPV-infected cells responsible for papilloma growth in RRP.
Currently, the most promising solution appears to be Precigen’s PRGN-2012 gene therapy which works by activating anti-HPV T cells to induce immunity against HPV subtypes 6 and 11, which are responsible for RRP.
If the on-going Phase 2 trial shows positive results, PRGN-2012 could be on its way to becoming a standard of care for reducing the burden of surgeries, lowering care costs and improving the quality of life of RRP patients.
In a study conducted on behalf of Wells Fargo, 10 ear, nose, throat physicians who treat RRP responded very favorably to the use of a drug with a PRGN-2012-target profile of safety and efficacy.
Precigen’s clinical-stage pipeline also includes Phase 1 and Phase 2 programs in immuno-oncology and infectious and autoimmune diseases. PRGN-2012 is Precigen’s innovative therapeutic vaccine for RRP patients.
Analyst price targets for PGEN as of August 2022 range from $6 to $14, with buy or market outperform ratings issued by Stifel, JMP Securities, Cantor Fitzgerald, and H.C. Wainwright.
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