Upstream Bio has sailed to a phase 2 win in sinusitis and plans to push its candidate forward against a competitive current.
Investigators randomized 81 adults with chronic rhinosinusitis with nasal polyps (CRSwNP) to receive the anti-TSLP antibody verekitug or placebo every 12 weeks. After 24 weeks, Upstream linked the study drug to a 1.8-point placebo-adjusted reduction in endoscopic nasal polyp score (NPS) compared with baseline. The result caused the trial to meet its primary endpoint.
Upstream posted hits on secondary endpoints, too. The biotech linked verekitug to a 0.8-point placebo-adjusted reduction from baseline in the patient-reported nasal congestion score (NCS). Upstream also hailed significant improvements in the need for systemic corticosteroids or nasal polyp surgeries and in total symptom scores.
With no serious adverse events reported, the biotech believes it has the data to support talks with regulatory agencies about further development of verekitug. Upstream used phase 2 efficacy endpoints that, pending talks with regulators, could produce data to support submissions for approval.
The biotech is advancing toward a market already served by Genentech and Novartis’ Xolair, Sanofi and Regeneron’s Dupixent (dupilumab) and GSK’s Nucala. Amgen and AstraZeneca have also filed for approval of TSLP drug Tezspire in the indication. While Tezspire targets the TSLP ligand, verekitug blocks the receptor. Upstream claims verekitug is about 300 times more potent than Tezspire.
The emergence of a set of biologic treatments for CRSwNP over the past five years has set the bar verekitug needs to clear to compete. Asked about expectations for the phase 2 trial, Upstream CEO Rand Sutherland, M.D., quoted data on dupilumab.
“Look at the label for dupilumab. There's about a 2-point change in the endoscopic nasal polyps score that was reported there. We think that that's probably relatively a floor for efficacy that we would want to see to be competitive,” Sutherland said at the J.P. Morgan Healthcare Conference in January. “I mean, there’s a little bit of room around that. We’ve powered to be even a little bit more robust than that.”
Verekitug could have an advantage even if it only matches the efficacy of existing biologics. The antibody was given every 12 weeks in the phase 2 trial, while Dupixent and Tezspire were given every two weeks and every four weeks, respectively, in their phase 3 CRSwNP trials. Upstream’s market research found about 90% of patients would consider switching to a product with a less frequent dosing interval.
William Blair analysts said the data drop "largely comes in line with data from Tezspire, which showed roughly a 1.7-point improvement over placebo at week 24 that further improved to 2.07 at week 52."
A sensitivity analysis of Upstream's results censoring patients receiving rescue steroids would boost the treatment difference to 1.9 points on the primary endpoint, likely surpassing Tezspire results at a similar timepoint, the analysts wrote in a Sept. 2 note.
While shares in Upstream fell 5.55% in premarket trading, the biotech's stock shot up nearly 20% to $20.26 by the end of the day Tuesday.
Upstream went public 11 months ago in an IPO that grossed $293 million. The biotech sold shares for $17 each in its IPO.
Editor's note: This story has been corrected to include more than premarket trading changes.