SELLAS Stock Up 346% in a Year as Cancer Vaccine Trial Nears Its Final 8 Deaths

A late-stage clinical biopharmaceutical company focused on immunotherapy for various cancers, SELLAS Life Sciences Group (NASDAQ:SLS) is at a genuinely unusual inflection point.

Its shares have climbed 346% over the past year, yet the stock pulled back 13.4% in the past week to $5.04, with Q4 earnings due March 19. The reason Reddit is buzzing: the Phase 3 REGAL trial for GPS, SELLAS’s WT1-targeting cancer vaccine in AML patients, needs 80 required patient deaths to trigger its final survival analysis, and as of late December 2025, the trial had recorded 72 of those 80 events.

Why a Slow Death Rate Is the Bullish Signal

The counterintuitive thesis driving SELLAS bulls is that the trial is taking longer than expected to reach that 80th event, and that is a feature, not a bug. Only 12 deaths occurred among 66 at-risk patients during the trial observation window, suggesting a lower-than-expected mortality rate versus the historical baseline for this patient population.

Reddit Sentiment Hits 88 on Competing Narratives

Social sentiment has been firmly “Very Bullish,” with scores ranging from 78 to 88 across r/stocks and r/wallstreetbets over the past 48 hours. The most detailed public case came from a r/wallstreetbets due diligence post by user Confident-Web-7118, who claims to hold 805,000 shares and spent over 1,000 hours on the analysis.

SLS DD post
by u/Confident-Web-7118 in wallstreetbets

“The ONLY mathematical shape that explains 72 events at month 58 with this deceleration pattern is a cure-fraction model on the GPS arm.” The author argues that the trial would require the control arm to post a median overall survival above the world record for this patient population to fail. A r/stocks thread drew 261 comments, with the original poster citing SLS as their top pick, having bought at $2.07.

SLS discussion thread
by the original poster in stocks

The bullish case rests on three pillars:

• Event deceleration in REGAL is statistically consistent with a large long-term survivor population in the GPS arm
• The IDMC has twice cleared the trial without modification, suggesting the two arms remain clearly separated
• Institutional ownership has grown from roughly 35-72 institutions pre-interim to 171+ as of March 2026, with Vanguard and BlackRock among those accumulating

The Valuation Risk Bulls Cannot Ignore

SELLAS generates zero revenue and trades at a 20x price-to-book ratio, compared with a biotech industry average closer to 2.5x. Short interest sits at 27% of float. Martin Shkreli publicly predicted drug failure on March 10, questioning the trial design and mechanism of action.

As it stands today, analysts are carrying a consensus price target of $7.83, but the stock is already trading near its 52-week high of $6.14. The final REGAL readout is expected by year-end 2026, and ultimately, this readout may well be the only number that matters.