Shkreli argued that the company lacks a clear mechanism of action and strong clinical data.
- The debate centers on Sellas’ Phase 3 Regal trial, which is testing its immunotherapy Galinpepimut-S (GPS) as a maintenance treatment for AML patients.
- The readout is nearing a key trigger, with eight more events needed to launch the final analysis in the event-driven study.
- Maxim noted that slower event accumulation in survival trials can sometimes suggest longer patient survival.
Shares of Sellas Life Sciences Group Inc. (SLS) rallied on Monday ahead of a closely watched readout from its late-stage acute myeloid leukemia (AML) trial, even as former hedge fund manager Martin Shkreli said he remains “very bearish” on the stock and expects the drug to fail.
SLS stock jumped nearly 8% on Monday to end at 5.96, hitting its highest levels in about four years, and gained another 2% in after-hours trading.
Shkreli Stays Bearish On Sellas
Shkreli, responding on X to a user who asked whether he was still bearish on Sellas, said: “Very bearish, it will fail.” In a separate post, he said that the company has no clear mechanism of action and lacks strong clinical data.
The comments come as Sellas moves closer to a potentially market-moving update from its Phase 3 Regal study evaluating Galinpepimut-S, or GPS, in AML.
Shkreli’s latest comments build on a skeptical view he had already expressed in 2024, when he published a long video discussion analyzing Sellas and its Regal trial. In the review, he questioned the trial design, the patient population and the statistical hurdles the study would need to clear.
He argued that the trial was being run in a difficult AML setting, with patients in second complete remission after relapse, and said the study’s sample size of about 127 patients could leave little room for error. He also suggested that showing a meaningful overall survival benefit in that population could be difficult.
His fresh comments are notable as they come just months after he publicly walked back another high-profile bearish biotech call. In December, after Capricor Therapeutics posted positive Hope-3 data, Shkreli acknowledged that it had been “a bad call” and apologized to followers who acted on his short thesis.
Regal AML Readout Nears
Investor focus is now centered on the timing of the Regal readout. Sellas said in late December that the contract research organization overseeing the Phase 3 trial had recorded 72 events as of Dec. 26, 2025. The study needs 80 events to trigger the final analysis, meaning it was eight events short of that threshold at the time of the company’s last update.
The trial is testing GPS as a maintenance treatment for AML patients whose disease had returned but later went back into remission after additional therapy. The main goal is to determine whether the drug improves overall survival.
Since the study is event-driven, the company has not given a fixed date for the readout. Instead, the timeline depends on when the 80th event occurs. Once that threshold is reached, the study will be unblinded and analyzed.
That timeline has kept investors focused on the stock since late last year. Sellas shares surged more than 100% during December alone as traders positioned ahead of the potential catalyst.
Sellas CEO Backs GPS Strategy
Over the weekend, Sellas CEO Angelos Stergiou said that GPS will target leukemia regardless of genetic mutations. He said the therapy targets the Wilms Tumor-1 (WT1) antigen and is designed to activate multiple types of T cells, so the immune system can attack leukemic stem cells and remaining cancer cells.
Meanwhile, Maxim noted that in survival-driven trials, a slower buildup of events can sometimes indicate longer patient survival.
How Did Stocktwits Users React?
On Stocktwits, retail sentiment for SLS shifted to ‘extremely bullish’ from the ‘bullish’ zone over the past day amid a 580% surge in 24-hour message volume.
One user called SLS the “Most organic growth biotech stock in the history of biotech stocks!!”
Another user pushed back on Shkreli’s stance, saying “his primary arguments were extremely flawed,” while noting the stock has risen sharply since he previously criticized it when it traded near $1.
SLS stock has skyrocketed 400% over the past year.
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