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Shares of Sellas Life Sciences Group Inc. (SLS) jumped to over a three-year high on Monday as investors await the final readout of its late-stage acute myeloid leukemia (AML) therapy, with analysts signaling the delayed event timing could indicate stronger survival outcomes.
SLS stock has finished in the green in 11 of the last 12 sessions, gaining more than 5% on Tuesday to close at $5.31.
The rally comes as the company’s Phase 3 Regal study evaluating Galinpepimut-S (GPS) in AML approaches the event threshold required to trigger the final analysis. The stock has surged ahead of the potential data catalyst, gaining more than 100% during December alone.
Sellas said in late December that the contract research organization overseeing the Regal trial reported 72 events as of Dec. 26, 2025, placing the study close to the 80 events required to initiate the final analysis.
The trial is testing GPS as a maintenance treatment for AML patients whose cancer returned but went back into remission after additional therapy. The study’s main goal is to see whether the drug helps patients live longer.
Since the trial is event-driven, the timing of the final readout depends on the time of the 80th event. The company said it will announce the milestone once it is reached. Sellas also noted that it remains fully blinded to the efficacy and survival outcomes.
Once the 80-event threshold is reached, the study will be unblinded and analyzed to determine whether the therapy improves survival outcomes for AML patients.
After the December update on the Regal trial by Sellas, Maxim said that “in any clinical trial, pinpointing the timing of events and survival timelines is challenging.”
The brokerage said that while top-line data had been expected by the end of 2025, delays in event-driven studies like Regal can sometimes indicate longer survival among patients, though the firm noted the results remain fully blinded and it is too early to draw conclusions.
Despite the recent rally, analysts still see additional upside potential. According to Koyfin consensus estimates, the stock carries an average 12-month price target of $6.83, implying a 29% upside from current levels.
Analyst sentiment remains positive, with one 'Buy' rating and two 'Hold' ratings among covering analysts, while the average analyst rating stands at 'Strong Buy' on a five-point scale.
On Stocktwits, retail sentiment for SLS was ‘extremely bullish’, with message volume rising 47% over the past 24 hours. Activity on the platform has also surged more than 1,000% over the past month.

One user said, “Just a reminder that there are 99.99% chances of success for REGAL. Failure is a statistical impossibility.”
Another user noted, “Nice steady climb on decent volume. A PR Friday morning would be epic.”
SLS stock has risen 41% year-to-date.
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