A hazard ratio of 0.43 for overall survival, drawn from an immature dataset in a 353-patient randomized trial, is the number that will dominate hallway conversations at EHA 2026 long after the spleen response tables have been absorbed. The Phase 3 SENTRY trial of selinexor plus ruxolitinib in frontline myelofibrosis met its first co-primary endpoint convincingly: 49.8% of patients on the combination achieved SVR35 at week 24 versus 28% on ruxolitinib alone. That gap held at weeks 12 and 36 as well, which matters because durability is exactly where single-agent JAK inhibition has historically struggled.
The second co-primary endpoint, absolute total symptom score improvement, did not separate statistically from the control arm. Both arms improved by roughly 10 points, which tells a specific story: selinexor’s XPO1 inhibition adds measurable spleen biology on top of ruxolitinib’s JAK1/2 blockade, but the symptom burden those two pathways share is apparently not additive in the same way. That asymmetry between the two co-primary outcomes is the central interpretive challenge this data set leaves on the table. Regulators evaluating a combination approval will have to weigh a robust spleen response against a flat symptom score delta.
The OS signal deserves careful handling precisely because it is early and immature, but a greater-than-50% reduction in the risk of death as a pre-specified secondary endpoint is not a number to dismiss. Post-hoc and Phase 1 SENTRY analyses both suggest SVR35 predicts OS, which gives the spleen response data a survival dimension that single-endpoint readouts in myelofibrosis rarely carry. Adding further texture, 32% of patients on the combination showed variant allele frequency reduction at week 24 versus 23.9% on monotherapy, a pre-specified exploratory marker linked to disease modification rather than purely symptomatic control. Myelofibrosis carries a median survival after diagnosis of roughly six years, and the JAK inhibitor class now includes four approved agents competing on overlapping but differentiated patient populations.
The single number to watch from here is the OS hazard ratio at the next pre-specified interim analysis. If mature survival data confirms the 0.43 signal even partially, it transforms this combination from a spleen-response add-on into a regimen with a survival argument, which changes the regulatory and reimbursement conversation entirely.
Jon Napitupulu is Director of Media Relations at The Clinical Trial Vanguard. Jon, a computer data scientist, focuses on the latest clinical trial industry news and trends.
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Karyopharm to Submit Selinexor-Ruxolitinib sNDA for Myelofibrosis in August 2026
3 weeks ago[…] survival readout. That distinction shapes everything: the FDA has told Karyopharm in writing that SVR35, spleen volume reduction of at least 35% at week 24, qualifies as a reasonably likely surrogate […]
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