The U.S. FDA has given a swift and full approval to Precigen Inc.’s gene therapy, Papzimeos (zopapogene imadenovec), for treating adults with recurrent respiratory papillomatosis (RRP), a rare and chronic disease characterized by benign tumors in the respiratory tract.

The priority BLA for the first-of-its-kind nonreplicating adenoviral vector-based immunotherapy had an Aug. 27 PDUFA date, which was set in late February. At the time, the PDUFA date announcement was coupled with a mention from Precigen that the FDA had indicated it did not plan to hold an advisory committee meeting to discuss the application. 

“Randomized trials are not always needed to approve medical products, and this approval is proof of that philosophy,” said Vinay Prasad, the FDA’s recently returned CBER director, said of the approval. “The FDA will always demand the correct clinical study for the specific medical product and disease. Our requirements for products given to tens of millions of healthy people will be different than products given to at most hundreds or thousands of patients with unique diseases.”

The full approval that needs no confirmatory study was speedy and welcome, according to H.C. Wainwright analyst Swayampakula Ramakanth. He had expected a positive decision from the FDA, but he had not expected it to come two weeks ahead of the PDUFA date.

“In our view, the FDA’s unprecedented way of providing full approval without a need for a randomized study underscores the unmet need in RPR, and that the strong data package from the open-label study aided in the drug’s speedy regulatory approval,” Ramakanth wrote.

Wainwright anticipates Papzimeos, a subcutaneously injected therapy with orphan drug and breakthrough therapy designations, will generate sales in the first full year about $138 million, and rise to $1.1 billion in 2033. Wainwright has raised its 12-month price target to $8.50 per diluted share from $6 each.

Germantown, Md.-based Precigen ’s stock (NASDAQ:PGEN) saw a 74% spike since the opening bell, with shares going for $3.22 each.

This is Precigen’s first approval and the first FDA-approved therapy for RRP. The drug targets a disease that the company estimates at about 1,000 newly diagnosed cases every year. It can lodge in the upper and lower respiratory tracts and is caused by chronic HPV 6 or 11 infections. Patients’ voices can become hindered and their airways are often then blocked. Pneumonia comes and may return after the obstructions are removed by surgery, which has been a typical RRP management technique. The surgeries, according to Precigen, mount into the hundreds. Some patients develop cancers that turn malignant. 

The approval came courtesy of an open-label, single-arm, pivotal trial that hit its primary safety and efficacy endpoints. Slightly more than half of the participants, 18 of 35, registered complete responses and needed no surgery a full year after treatment. In the ongoing study, 15 of the 18 participants had continued complete responses at 24 months.

The treatment was well-tolerated, and there were no dose-limiting toxicities or treatment-related adverse events worse than grade 2. Papzimeos also resulted in HPV 6/11-specific T-cell responses in RRP study patients with a significantly greater expansion of peripheral HPV-specific T cells in responders compared with nonresponders, the company said.