Do the PAPZIMEOS and INO-3107 trials measure the same thing?

INO-3107 and the PAPZIMEOS precedent · INO-3107 · 2025 – 2026

51% vs. 28.1%: the FDA decision behind two RRP treatments

One treatment is FDA-approved. Another faces an FDA decision by October 30. Their headline results look like a clear win for the approved drug. But the percentages don't measure the same thing.

EphemerisX Research · Published October 8, 2026 · 7 source documents · 2 min read

In recurrent respiratory papillomatosis (RRP), patients can undergo surgery again and again to remove growths in their airways. Preventing those surgeries is the goal both treatments are measured against.

Precigen's PAPZIMEOS received FDA approval in August 2025. In its pivotal trial, 51% of patients had no clinically indicated surgical interventions during the 12 months following treatment ¹.

INOVIO reports that 28.1% of patients in its INO-3107 trial, 9 of 32, required no surgical intervention during or after the dosing window ². The FDA is due to act on INO-3107 toward a PDUFA target action date of October 30, 2026 ³.

At first glance PAPZIMEOS has the stronger result. But the trials enrolled different patients, counted different outcomes and were built around different primary endpoints. The numbers tell us something about each treatment. They do not establish which treatment is better.

Two headline results. Two different measures.

Percentage of patients meeting each reported outcome

PAPZIMEOS

51%

No clinically indicated surgery during the 12 months following treatment ¹; surgery allowed during treatment: optional surgical debulking on day 43 and/or day 85 ⁴
Patients requiring three or more surgical procedures per year ⁵; 18 of 35 ¹
The trial's primary endpoint; FDA-approved August 2025 ⁶

INO-3107

28.1%

No surgical intervention during or after the dosing window ²; surgery during dosing was counted against the efficacy endpoint ⁷
Patients with two or more surgeries in the year prior to treatment ⁸; 9 of 32 ²
Not the primary endpoint, which was safety and tolerability ⁹; INOVIO's account, under FDA review

Why this is not a head-to-head comparison: the trials differed in who they enrolled, which months they counted and what they were designed to measure. No trial in this record tests both treatments under one protocol, so the percentages are not a direct measure of one drug's superiority over the other.

The trials, side by side

In the FDA's and the companies' words

	PAPZIMEOS (Precigen)	INO-3107 (INOVIO)
Design	a single-arm, open-label Phase 1/2 study ⁵	a Phase 1/2 trial evaluating INO-3107 ⁸
Who enrolled	three or more surgical procedures per year ⁵	two or more surgeries in the year prior to treatment ⁸; a median of 4 surgeries (overall range of 2-8) ¹⁰
Primary endpoint	complete response (CR) rate at 12 months ¹	safety and tolerability ⁹
Window counted	the 12 months following treatment ¹	during or after the dosing window ²
Dosing	four subcutaneous injections of PAPZIMEOS on days 1, 15, 43, and 85 ⁵	received four doses of INO-3107, once every three weeks ⁹

Why the difference matters now

INO-3107 is under review for accelerated approval. INOVIO's 10-K explains what a competitor's full approval does to that path: the disease would no longer qualify as one for which there is no available therapy, and accelerated approval of our product candidate would not occur without a showing of benefit over available therapy ¹¹. With PAPZIMEOS approved, INOVIO expects the FDA to look for a clinically meaningful benefit over existing therapies, including PAPZIMEOS ¹².

That puts the comparison at the center of the review, but not as a scoreboard: nothing in the record says INO-3107 must post a higher percentage than PAPZIMEOS. When the FDA accepted the application, it noted its preliminary conclusion that the Company has not submitted adequate information to justify eligibility for the accelerated approval pathway ¹³.

The open question

What evidence will the FDA accept for INO-3107's accelerated-approval path, and what can the existing results establish? The public record does not yet say. At a July 2026 meeting, INOVIO reports, the FDA did not discuss its preliminary commentary in the file acceptance letter regarding accelerated approval eligibility ¹⁴, and said feedback on the confirmatory trial design would be forthcoming ¹⁴.

The FDA's action, due by October 30, 2026 ¹⁵, and any review it publishes will be the first FDA account of INO-3107's evidence, and the first sign of how the agency weighs it now that the disease has an approved therapy. How do INOVIO and Precigen describe each other's product?

Follow the thread

What evidence did the FDA accept when it approved PAPZIMEOS?PAPZIMEOS's single-arm study
How do INOVIO and Precigen describe each other's product?43% at 24 months

The documents, by date

The passages quoted

1FDA Summary Basis for Regulatory Action, August 14, 2025 · page 5

The primary endpoint, complete response (CR) rate at 12 months, defined as the percentage of subjects with no clinically indicated surgical interventions during the 12 months following treatment, was achieved in 51% of patients (18/35; 95% CI 34% to 69%). Furthermore, 15 patients maintained complete response at 2 years yielding a 24-month complete response rate of 43% (15/35; 95% CI 26% to 61%).