SLS Stock Pops Big After Hours On Imminent Leukemia Trial Data Readout Optimism

• SELLAS is advancing two key programs in AML.
• For Q1, SLS reported a higher net loss as it prepares for a potential application filing to the U.S. Food and Drug Administration for GPS. 
• The data readout from the GPS trial will be triggered by a pre-specified event. 
   

Shares of SELLAS Life Sciences Group (SLS) jumped more than 20% in after-hours trading Monday following the company’s announcement that its pivotal late-stage trial of galinpepimut-S (GPS) in acute myeloid leukemia (AML) is now just two events away from triggering topline data readout.

As of May 11, 2026, 78 deaths had occurred in the study, called REGAL, the company said. The prespecified 80th event will trigger analysis and disclosure of results, the company said. SELLAS remains blinded to the data as the study is being conducted by a contract research organization.

In December, the company reported that 72 out of the prespecified 80 patient deaths required to trigger the final analysis had occurred as of Dec. 26, 2025.

“...we believe that the upcoming results, triggered by reaching the pre-specified 80th event, will be an important milestone for the Company,” Sellas CEO Angelos Stergiou said.

Pipeline Highlights

SELLAS is advancing two key programs in AML. In addition to the REGAL trial, the company has begun dosing patients in an 80-patient mid-stage trial of its experimental drug SLS009 in newly diagnosed, first-line AML patients, including high-risk subsets. Topline data from this study are expected in the fourth quarter of 2026.

Stergiou said that Sellas is “entering an exciting time with multiple, high-value potential catalysts that could transform the AML treatment landscape.”

Financial Results and Guidance

As of March 31, 2026, SELLAS had $107.1 million in cash and cash equivalents. The company has since received an additional $7.5 million from the exercise of warrants in the second quarter, extending its cash runway.

The company has also established a new at-the-market (ATM) equity facility that gives it the ability to raise up to $150 million over time, though no shares have been sold under the program to date.

For the first quarter ended March 31, 2026, SELLAS reported a net loss of $8.4 million, compared with a net loss of $5.8 million in the year-ago period. The increase was driven primarily by higher research and development spending as the company prepares for a potential application filing to the U.S. Food and Drug Administration for GPS following the REGAL readout.

How Did SLS Retail Traders React?

On Stocktwits, retail sentiment around SLS rose from ‘neutral’ to ‘bullish’ territory over the past 24 hours, while message volume increased from ‘normal’ to ‘high’ levels.

A Stocktwits user voiced hopes for further rally.

Another expressed anticipation for the REGAL trial data, noting that it is “nearly here.”

A third user expressed optimism for the data triggering an FDA approval, causing a 10x jump in share price.

According to data from Koyfin, the two analysts covering Sellas rate it ‘Buy’ or higher. The 12-month average price target on the stock is $10, representing a potential upside of over 90% from the stock’s closing price on Tuesday.

SLS stock has more than tripled over the past 12 months. 

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