Belenos Biosciences’ bet worth up to $185m on Keymed Biosciences’ subcutaneous chronic rhinosinusitis with nasal polyps (CRSwNP) therapy is showing early signs of paying off, following a Phase II win in a Chinese study.
The mid-stage trial (NCT06930612), which enrolled 120 patients with CRSwNP, tested different dosing amounts and schedules of the drug dubbed BEL512 alongside daily, nasally-administered corticosteroid treatment. In a topline readout, the drug triggered a significant change in patient nasal polyp scores from baseline at week 24 – meeting the trial’s primary endpoint.
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On top of meeting its preliminary goal, BEL512 also met its secondary endpoints at week 24, offering improvements in nasal congestion and total symptoms of CRSwNP, while also reducing patients’ loss of smell.
Patients also tolerated BEL512 well, with the rate of treatment-emergent adverse events (TEAEs) remaining similar between the therapy and placebo groups.
While detailed data on this Phase II trial’s readout is not yet available, Belenos notes that further information on the results should soon be presented at a scientific meeting.
Belenos acquired the ex-China rights to BEL512 through a licensing deal with Keymed in 2024, which saw the company hand over $15m upfront for the asset.
BEL512, known as CM512 in Greater China, is a long-acting bispecific antibody that Keymed has engineered to inhibit both thymic stromal lymphopoietin (TSLP) and interleukin-13 (IL-13). Through its ability to target both up- and downstream drivers of inflammation, Keymed and Belenos propose that BEL512 could offer broad and durable control of type 2 inflammation, such as that seen in CRSwNP.
According to CEO of Belenos, Donnie McGrath, the Phase II findings provide “important clinical validation” for targeting TSLP and IL-13 in tandem for CRSwNP treatment.
“The magnitude, speed of onset and durability of improvement across objective measures of nasal polyp disease and the symptoms that matter most to patients, in conjunction with infrequent dosing indicate that BEL512 may offer patients an attractive treatment option,” McGrath commented.
“These findings further strengthen our conviction in BEL512 as a potentially best-in-class therapy across multiple respiratory and inflammatory diseases,” he added.
With these positive results in hand, Keymed is looking to begin a Chinese Phase III study on CM512, while Belenos is eyeing an ex-China Phase III study initiation in the first half of 2027.
Challenging Dupixent’s reign in CRSwNP
While this Phase II win will be a positive step forward for Belenos as it looks to break onto the CRSwNP market, it is currently unclear how BEL512, if approved, would fare against established drugs such as Sanofi and Regeneron’s Dupixent (dupilumab).
Since its approval in 2019, Dupixent has dominated the treatment landscape for many type 2 inflammatory diseases – the umbrella under which CRSwNP sits – due to its strong efficacy and durability across dermatological, rheumatological and respiratory conditions. In 2025, Dupixent generated $17.8bn in global sales alone.
Now, Belenos and other biopharma companies are looking to gain market share with new targets and long-acting therapies.
Similar to Dupixent, which has nine approved indications under its belt in the US, BEL512 is under development for several distinct conditions – including asthma, chronic spontaneous urticaria (CSU), eczema and chronic obstructive pulmonary disease (COPD).
