ASCO-GU 2026 – late-breakers in focus

Merck & Co’s attempts to breathe new life into its HIF-2α inhibitor Welireg in kidney cancer will come under the spotlight at the upcoming ASCO genitourinary cancers symposium, whose late-breaking sessions will feature two phase 3 studies said to have yielded positive results last October, Litespark-011 and 022.

ASCO has also moved fast to include another recent win in its programme, Padcev’s Keynote-B15 study, which was only toplined in late December. Also highly notable is Flare Therapeutics, whose first-in-human trial of the PPAR-γ inhibitor FX-909 has scored a late-breaker – a major success for a low-key, private US biotech.

That said, mainstream focus will likely fall on Welireg, and whether this HIF-2α inhibitor has a chance of approval beyond its current main use of post-PD-(L)1/VEGF renal cell cancer, in which it was greenlit in 2023. Litespark-011, in post-PD-(L)1 renal cancer, will be scrutinised for its lack of overall survival benefit, despite an apparent win on PFS.

Merck will hope for parallels with the approved third-line setting, in which Litespark-005 similarly hit on PFS but not on OS. Litespark-022, meanwhile, concerns the adjuvant setting as part of a Keytruda combo, but nothing has been said apart from its win on disease-free survival versus Keytruda; in Keynote-564 Keytruda alone yielded a 12-month DFS rate of 85.5%.

At present no data from any ASCO-GU presentations have been revealed, and only the abstract titles are available. Most abstracts will go live on 23 February, three days before the conference starts.

Selected presentations at ASCO-GU 2026

Source: ASCO.

Similarly, no data are available for the Keynote-B15/EV-304 study of Padcev plus Keytruda, said to have yielded statistically significant and clinically meaningful event-free survival and OS results. This concerns perioperative muscle-invasive bladder cancer, but specifically in cisplatin-eligible patients; the combo is already approved in cisplatin-ineligibles.

ASCO-GU is also highlighting the Litespark-011 and 022, and Keynote-B15 late-breakers in its press programme.

A separate Pfizer late-breaker at ASCO-GU concerns disitamab vedotin, in the Keynote-D78 study in HER2-positive bladder cancer. However, the commercial relevance of this is unclear given Pfizer’s recent decision to deprioritise this Seagen-derived anti-HER2 ADC in bladder cancer, citing the growing dominance of Padcev.

Flare scores

It’s likely that ASCO-GU will be far more momentous for Flare Therapeutics, a Massachussetts-based biotech that has so far had a fairly low-key existence, and which last tapped venture financiers in March 2023 in a $123m series B raise. Flare’s lead molecule, FX-909, appears to be the only PPAR-γ inhibitor being developed in oncology.

PPAR agonists have been extensively tested in liver diseases, but Flare reckons inhibiting PPAR-γ is relevant because 65% of urothelial bladder cancers are characterised by high PPAR-γ expression. Phase 1 data at last year’s Triple (AACR-NCI-EORTC) meeting showed four partial and one complete response among 46 patients, and ASCO-GU will feature the same study, with results possibly zeroing in on a selected phase 2 dose in a biomarker-defined population.

Away from the late-brakers, ASCO-GU will feature more data on Vir’s masked anti-PSMA T-cell engager VIR-5500, a molecule whose early data in prostate cancer already raised questions about Sanofi’s decision to let this asset go. More results with favezelimab are less relevant given Merck’s decision to discontinue this anti-Lag-3 MAb.

ASCO-GU takes place in San Francisco on 26-28 February 2026.