ASCO 2026 preview – Pumitamig looks similar to ivonescimab again

Rival PD-(L)1 x VEGF inhibitors from BioNTech/Bristol Myers Squibb and Summit/Akeso have looked more similar than different, and this appears to be the case again – this time in first-line non-small cell lung cancer.

Data from the phase 2/3 Rosetta Lung-02 trial of BioNTech and Bristol’s pumitamig, just revealed in an ASCO abstract, are the first global results with any PD-(L)1 x VEGF in front-line NSCLC. However, they only concern the phase 2 portion, and the partners are still playing catch-up with Summit/Akeso’s ivonescimab. The latter has already yielded pivotal Chinese data in this setting, with the US Harmoni-3 study set to read out this year.

Rosetta Lung-02

Rosetta Lung-02 tests pumitamig plus chemo, versus Keytruda plus chemo, in first-line NSCLC with both squamous and non-squamous disease.

The ASCO data come from the uncontrolled dose-finding phase 2 portion, which tested pumitamig at 1.4g and 2.0g, and has primary efficacy endpoints of overall response rate and best percentage change from baseline in tumour size.

The abstract claims an response rate of 70% among 40 patients across histologies and doses – but a closer look shows a confirmed ORR of just 53%. Furthermore, among the seven unconfirmed responses, only five are pending confirmation, suggesting that the other two responders have relapsed and won't be confirmed.

Rosetta Lung-02: pumitamig in front-line NSCLC

Notes: *5 of 7 unconfirmed responses are pending confirmation; **includes unconfirmed responses. Source: ASCO abstract.

Splitting by histologies, squamous patients did better. And the 1.4g dose outperformed 2.0g, with ORRs of 82% and 63% respectively in squamous patients, and 73% and 60% respectively in non-squamous patients. This suggests that the lower dose will be taken forward into the phase 3 portion, which will test the pumitamig/chemo combo versus Keytruda plus chemo.

The abstract also claims activity across PD-L1 levels, but doesn't break this down.

One relevant comparator is Akeso's Chinese Harmoni-6 trial of ivonescimab plus chemo in first-line NSCLC – although this only enrolled squamous patients.

Here, Akeso claimed a 76% best response rate among 266 patients at ESMO last year, but this also appears to include unconfirmed responses – putting it in line with pumitamig’s 74% unconfirmed response rate in the squamous subtype.

Survival

In any case, ORR is no longer the focus for Harmoni-6, which has progression-free survival as its primary endpoint. Ivonescimab comfortably beat Tevimbra on this measure, although a big question is how the project might fare against Keytruda.

Overall survival data from Harmoni-6 will also feature at ASCO in a plenary session.

Meanwhile, the analogous global study is Harmoni-3 which, like Rosetta Lung-02, is enrolling both squamous and non-squamous histologies, and has Keytruda plus chemo as control. However, Harmoni-3 recently took a blow when it passed an interim PFS analysis in squamous patients without returning a positive result.

Summit had tinkered with that trial’s design to give it a shot at earlier FDA approval – a move that's so far come to nothing. The final PFS analysis in squamous patients is set for the second half, while data in non-squames are expected in 2027.