Exelixis slips out a zanzalintinib delay

Exelixis’s first-quarter presentation was all about its Cabometyx follow-on zanzalintinib, but alongside new trial starts the company snuck in a delay to a key study, Stellar-304. That trial, in first-line non-clear cell renal cancer, is now expected to read out in the second half; Exelixis had once guided to results in late 2025. One co-primary endpoint is PFS, and it appears that event rates have been slower than expected. This could indicate that zanzalintinib, which is being combined with Opdivo, is performing well – but could also be down to better than expected survival in control patients, who received Sutent. Only around 20% of renal cancers have non-clear cell histologies; in clear cell disease Exelixis has pinned its hopes on a combination with Merck & Co’s HIF2α inhibitor Welireg. Elsewhere, zanzalintinib is awaiting an FDA approval decision in third-line colorectal cancer, although there it’s unclear whether the compound is less toxic than Cabometyx, as hoped. Exelixis also disclosed a new phase 2, Stellar-202, testing a Keytruda combo in NSCLC maintenance; and a new cohort to the phase 1 Stellar-002 study, evaluating a docetaxel combo in castration-resistant prostate cancer. Exelixis reckons zanzalintinib has a $1.5bn market opportunity in third-line colorectal cancer alone. Key trials of zanzalintinibTrialSettingRegimenNoteStellar-3033rd-line colorectal cancer+ Tecentriq, vs StivargaPDUFA date 3 Dec 2026 based on ITT data; final OS data in non-liver mets pts due mid-2026Stellar-3041st-line non-clear cell renal cancer+ Opdivo, vs SutentData due H2 2026 (from mid-2026 & H2 2025 previously)Stellar-311*2nd-line neuroendocrine tumoursMonoRx, vs AfinitorStarted Jul 2025; completes Jun 2029Litespark-0331st-line clear-cell renal cancer (post-adjuvant PD-(L)1)+ Welireg, vs CabometyxStarted Nov 2025; completes Feb 2032Litespark-0342nd-line clear-cell renal cancer (post-1st-line PD-(L)1 + VEGF-TKI)+ Welireg, vs WeliregStarted Apr 2026; completes Nov 2030Stellar-201**2nd-line meningiomaMonoRx, uncontrolledStarted May 2026; confirmatory ph3 plannedStellar-316Adjuvant colorectal cancer (MRD+ve but no radiographic evidence of disease)+/- PD-(L)1i, vs placeboTo start mid-2026Stellar-202**Squam NSCLC, 1st-line maintenance (following Keytruda + chemo induction)+ KeytrudaTo start H2 2026Note: *phase 2/3; **phase 2. Source: OncologyPipeline & company presentation.