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Sellas Life Sciences: REGAL Trial's Early Event Count Raises Bias Questions
Sellas shares rallied ahead of REGAL trial data. Early event counts may signal selection bias, not a treatment effect. A Seeking Alpha analyst flagged the risk. The binary outcome hinges on whether the signal holds at maturity.
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Sellas Life Sciences shares have rallied in recent sessions as investors position ahead of the Phase 3 REGAL trial data. The trial tests galinpepimut-S as a maintenance therapy in acute myeloid leukemia. The stock's move implies the market expects a positive readout.
The problem with that trade is that early-reported events in an event-driven oncology trial can mislead. A Seeking Alpha analyst covering the name flagged the issue: delayed events in the trial could signal selection bias, not a genuine treatment effect. If patients with slower-progressing disease are overrepresented in the early-event tally, the interim look would overstate the drug's benefit. That kind of bias is hard to detect from top-line summaries alone.
The REGAL trial's primary endpoint is overall survival. The trial passes if the galinpepimut-S arm shows a statistically significant improvement over the control arm. Timing of events matters. A treatment that genuinely works should produce a consistent divergence in survival curves over time. If the early events cluster in a way that looks too good too fast, the chances of a fade on mature data rise.