ASCO 2025 preview – Merus tops Bicara

ASCO's first skirmish, between Merus and Bicara's EGFR-targeting bispecifics in head and neck cancer, has yielded a win for the former. Merus has again been helped by press releasing results from a study of petosemtamab that gave more impressive numbers than its ASCO abstract, while Bicara investors only have the ficerafusp alfa abstract to go on, with full data held back until 1 June.

These are just two datasets among the regular abstracts ASCO unveiled on Thursday; those relating to late-breakers remain under wraps until their day of presentation, and were covered by ApexOnco separately. Among presentations featuring biologicals, 3SBio's SSGJ-707 is also in focus, having been licensed to Pfizer for $1.25bn up front a few days ago.

SSGJ-707, an anti-PD-1 x VEGF bispecific, is reported as yielding a responses rate of 62% among 34 PD-L1-expressing first-line NSCLC patients. On a cross-trial basis this looks better than the 50% ORR Akeso/Summit's high-profile similarly acting drug ivonescimab yielded in a broadly similar population in the Harmoni-2 study.

Ivonescimab is a notable absentee from this year's ASCO. However, BNT327, an anti-PD-L1 x VEGF bispecific BioNTech acquired through its $800m purchase of Biotheus, does feature, though its first-line mesothelioma abstract has an extremely old data cutoff, so more up-to-date results will hopefully come at the meeting itself.

Merus vs Bicara

On Friday Merus shares surged 28% while Bicara, which only went public on Nasdaq last November, saw its stock plummet 35%.

Petosemtamab and ficerafusp differ in the second target of their bispecific (LGR5 and TGF-β respectively) and in their format (antibody versus fusion protein), but both target front-line PD-L1-positive head and neck cancer in combination with Keytruda. At the last count petosemtamab yielded a 62% ORR among 26 patients, apparently irrespective of HPV status.

This number held up in the ASCO abstract, which cites a 60% ORR among 43 patients at a 16 September cutoff. However, at an investor event on Thursday Merus unveiled full data as at a 27 February 2025 cutoff; here it reported a 63% confirmed ORR among the 43 subjects, including 50% in eight HPV-positive and 66% in 35 HPV-negative patients. 14 of the 27 responses are ongoing, including 10 at over 12 months.

Bicara's abstract cites a 54% ORR in 39 patients, but as before the worry is that responses are confirmed to HPV-negative disease: the implied ORR in 11 HPV-positive patients is just 27%. Investors in Bicara, effectively a one-trick pony, will hope for a positive update during ASCO itself.

Meanwhile, among other biologicals BioNTech's struggles in Claudin6 continue. After disappointing with the Car-T approach (BNT211) at last year's ESMO, an mRNA-encoded T-cell engager (BNT142) might be even less efficacious, with the ASCO abstract reporting no specific efficacy, merely citing an unspecified number of partial responses in ovarian cancer patients.

And in cell therapy presentations Allogene is reporting modest response rates for its CD70-directed Car-T project ALLO-316, with a promising sign that efficacy is tied to CD70 expression. Modest activity, albeit in glioblastoma, is also seen from an intriguing project owned by Gilead, TmEGFRIL13Rα2-01, described as bivalent Car T-cells targeting EGFR epitope 806 and IL13Rα2.

Selected ASCO 2025 regular presentations for biologicals, excluding ADCs

ASCO takes place in Chicago on 30 May to 4 June.