TLDR
- Sellas Life Sciences stock has surged roughly 100% year-to-date, closing around $2.14 on October 17, 2025, and spiking another 38% in after-hours trading.
- BlackRock disclosed a 5.4% stake in the company on October 18, representing approximately 5.7 million shares, while other major institutions like Vanguard and Marshall Wace also increased positions.
- The company’s lead AML immunotherapy galinpepimut-S passed an interim safety review in its Phase 3 REGAL trial, with final results expected by late 2025.
- SLS009 (tambiciclib) showed a 44% response rate in a Phase 2 relapsed AML trial and delivered statistically improved survival results in a T-cell leukemia preclinical study presented at ESMO 2025.
- Analysts maintain Buy ratings with price targets around $6-$7, implying roughly 220% upside, while the company raised $23.6 million through warrant exercises in September 2025.
Sellas Life Sciences shares are trading around $2.10 as of October 20, 2025, following a remarkable run that has doubled the stock’s value this year. The company closed at $2.14 on October 17 before jumping another 38% in after-hours trading.
SELLAS Life Sciences Group, Inc., SLS
Trading volume tells the story of intensifying interest. On October 17, shares changed hands at three times normal volume while call-option activity spiked 761% above average.
The stock hit a 52-week low of $0.77 earlier this year. It’s now sitting near fresh highs.
BlackRock disclosed a 5.4% ownership position on October 18, holding approximately 5.7 million shares. For a biotech with a market cap around $230 million, that’s a meaningful vote of confidence.
The world’s largest asset manager wasn’t alone in building a position. Vanguard added roughly 3.82 million shares in Q2 while BlackRock itself increased holdings by 4.05 million shares, an increase of 752%.
Hedge funds like Marshall Wace, Geode, Millennium, and Morgan Stanley also took new stakes during the quarter. Even company insiders are buying, with board members Katherine Kalin and Jane Wasman each purchasing 20,000 shares recently.
Pipeline Drives Institutional Interest
Sellas’s lead drug candidate is galinpepimut-S, a WT1-targeted cancer vaccine. The therapy is currently in a Phase 3 trial called REGAL for acute myeloid leukemia patients.
In August 2025, an independent Data Monitoring Committee reviewed approximately 60 events in the trial. The committee unanimously recommended the study continue without changes and identified no safety concerns.
The final overall survival analysis triggers at 80 events. Management expects that milestone by year-end 2025, setting up a potential FDA filing in 2026.
The company’s second therapy, SLS009 (tambiciclib), is an oral CDK9 inhibitor showing promise in its own right. A Phase 2 trial in relapsed or refractory AML met all primary endpoints with a 44% overall response rate.
CEO Dr. Angelos Stergiou said the response rate at the optimal dose level nearly tripled median overall survival compared to historical benchmarks. The FDA agreed the drug can move into first-line AML studies based on these results.
Sellas plans an 80-patient trial in newly diagnosed or early-refractory AML patients with enrollment starting in early 2026.
Fresh Data at ESMO 2025
At the ESMO 2025 conference running October 17-21, Sellas presented new preclinical data on SLS009. The focus was T-cell prolymphocytic leukemia, an aggressive form of the disease.
In a patient-derived mouse model, SLS009 extended survival to 7.4-7.9 weeks. Mice treated with venetoclax alone lived only 4.4 weeks, making the difference statistically strong with a p-value below 0.05.
The treatment reduced blood tumor cells markedly without introducing new safety issues. Chief Development Officer Dragan Cicic called the findings highly encouraging and said they provide important preclinical evidence for CDK9 inhibition in this cancer type.
Dr. Francisco Vega from MD Anderson, the study’s lead author, noted the T-PLL mouse model closely mirrors human disease. That could speed up clinical translation of the therapy.
Wall Street Weighs In
Three analysts cover Sellas, all with Buy ratings. Maxim Group analyst Jason McCarthy maintained his Buy rating in July 2025 and raised his 12-month price target to $7.00 from $4.00.
The average analyst target sits around $6.83, with a range between $6.00 and $7.50. That implies roughly 219% upside from current levels.
Technical indicators also look favorable. The stock is trading well above its 20-day and 50-day moving averages.
There’s a wrinkle though. Short interest stands at approximately 18% of the float, meaning nearly one in five shares available for trading has been borrowed and sold short.
If positive news continues, those short sellers could face pressure to cover their positions. That could drive the stock higher in a squeeze scenario.
Weiss Ratings struck a contrarian note, assigning Sellas a Sell (D-) grade. The rating reflects the inherent risks that come with small-cap biotech investing.
Balance Sheet and Upcoming Events
Sellas ended Q2 2025 with $25.3 million in cash, down from $29.3 million at year-end. The company posted a net loss of $6.6 million or $0.07 per share for the quarter, an improvement from the $7.5 million loss a year earlier.
R&D spending was $3.9 million in Q2 as enrollment in the REGAL trial had already concluded. Then in September 2025, Sellas completed a financing that raised $23.6 million through warrant exercises.
That cash should carry the company through upcoming trial readouts and the planned first-line SLS009 study.
The company will host a virtual R&D Day on October 29, 2025. Management plans to review the AML pipeline with key opinion leaders and company scientists discussing GPS and SLS009 data.
Sellas licensed the GPS vaccine exclusively from Memorial Sloan Kettering Cancer Center. The therapy is being studied in combination with Merck’s Keytruda in a multi-cancer trial, while investigator trials have tested GPS with Bristol Myers Squibb’s Opdivo.
The company has expanded its scientific advisory board recently, adding experts including Drs. Philip Amrein, Alex Kentsis, and Linghua Wang.
As of October 20, the stock was trading at $2.10 per share with volume exceeding 10.7 million shares, more than four times the average daily volume.
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