ASCO 2025 preview – late-breakers in focus

On Wednesday the starting gun was fired for one of the year's most important oncology conferences, ASCO, with the unveiling of the titles of all abstracts selected for presentation. While the data remain under wraps, it's now clear which trials have earned prestigious slots at the meeting – and which haven't.

AstraZeneca, for instance, has scored two late-breakers to be presented at ASCO's Sunday plenary, a session that will also see full data from the Verify polycythemia vera study of Protagonist/Takeda's rusfertide. That Verify should be accorded such a late-breaker perhaps portends another relatively low-key ASCO, which again sees an absence of some of the most recent clinical readouts.

Among the absences, maybe the most prominent is Akeso and Summit's ivonescimab, whose first-line NSCLC chemo combo trial Harmoni-6 has just been toplined positive. Some analysts speculated that Akeso had submitted a placeholder for an ASCO late-breaker, but in the event this hasn't come to pass, with ASCO maintaining its usual adherence to strict submission deadlines.

Double plenary

For AstraZeneca scoring ASCO plenaries has become something of an annual tradition, and last year saw the company secure two such accolades, for the Adriatic study of Imfinzi and the Laura trial of Tagrisso.

There will be a repeat in 2025, this time with camizestrant's Serena-6 trial and Imfinzi's Matterhorn study. The former is a relatively low-key breast cancer study, which became a big deal courtesy of the fact that it monitored patients for development of the ESR1 resistance mutation, aiming to detect this before disease progression to inform an early switch to the SERD camizestrant.

In February Astra heralded a "highly statistically significant and clinically meaningful improvement in PFS", Serena-6's primary endpoint. Also in breast cancer, and with a similar mechanism to camizestrant, is Arvinas/Pfizer's vepdegestrant, whose disappointing readout in the Veritac-2 trial (showing a PFS benefit only in ESR1-mutant disease) was toplined in March, and which features at a non-plenary late-breaker.

Meanwhile, Matterhorn, a trial of Imfinzi in perioperative gastric cancer, was toplined positive for EFS in March, and it's these results that will feature at an ASCO plenary; Matterhorn pCR data are already published, and a key EFS comparator will be the data Merck & Co reported in Keynote-585, which failed on a technicality.

The full ASCO abstract texts go public at 5pm Eastern time on 22 May, except for late-breakers, which will go live at 7am Central time the morning of their presentations.

Selected ASCO 2025 late-breakers

Source: ASCO.

The big surprise for ASCO's plenary session has come courtesy of rusfertide, a hepcidin mimetic for which Takeda paid Protagonist $300m up front in a February 2024 licensing deal. This is a relatively low-key project for a pre-cancer indication, and the Verify trial's positive topline readout elicited a mere 4% rise in Protagonist's share price.

Outside the ASCO plenary, another low-profile asset that's scored a notable late-breaker is Corcept's oral glucocorticoid receptor antagonist relacorilant, whose platinum-resistant ovarian cancer study Rosella was said to hit on PFS in March. This was apparently thanks to Corcept focusing this phase 3 trial only on the subgroup that showed the most profound benefit in phase 2.

Among more established cancer drugs, Daiichi Sankyo/Astra's Enhertu also has a late-breaker, covering the Destiny-Gastric04 trial in second-line gastric cancer. This trial, where Enhertu has beaten Cyramza plus paclitaxel, is of marginal importance; Enhertu already has full approval for post-Herceptin gastric cancer, backed by Destiny-Gastric01, where it beat chemo.

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