Two Trials, One Stock: Sellas Life Sciences Nears a Pivotal Crossroads

Sellas stock surges over 500% as Phase 3 GPS trial nears unblinding at 80 events; SLS009 combo trial data due by end of 2026.

Behind the eye?catching stock performance of Sellas Life Sciences lies a pipeline with two distinct shots at the acute myeloid leukemia (AML) market. The biotech company is simultaneously advancing a Phase 3 study of its lead asset, Galinpepimut?S (GPS), and a separate combination trial for the CDK9 inhibitor SLS009. Together, these programs have turned the stock into a high?stakes bet that has already rewarded early investors handsomely — but is now waiting on precisely two data points before its next leg.

Sellas shares closed Friday at €11.30, after a twelve?month run that one report pegs at 567.85% while another puts the gain at 597%, a discrepancy that underscores how quickly percentages can shift with measurement windows. The stock touched a 52?week low of €1.22 in November 2025 before surging to a high of €15.25 on June 30, 2026 — a level from which it has since retreated 25.9%. Even so, the shares trade 44.77% above their 50?day moving average of €7.81 and a striking 183.4% above the 200?day line of €3.99. The 14?day relative strength index sits at 59.4, neutral territory that signals neither overbought nor oversold conditions.

The 80?Event Threshold That Has Everyone Watching

The real narrative centres on the REGAL Phase 3 trial of GPS. For the study to be unblinded, 80 deaths must be recorded in the patient population. So far the count stands at 78. The agonising wait for those final two events has injected a palpable tension into the stock’s trading. Sellas CEO Angelos Stergiou has suggested that the slow accumulation of events could actually be a positive signal — perhaps the treatment arm is extending survival. Skeptics point to possible selection biases. With the data locked until unblinding, the market is left to trade on interpretation rather than facts.

That ambiguity has fuelled extraordinary short?term swings. On a 30?day basis the stock has gained either 64.24% or 82.26%, depending on the source, while the annualised 30?day volatility stands at 127.1%. Over the past week the shares fell 7.38% in one account and 12.06% in another — a reminder that the path from €1.22 to €11.30 has been anything but linear. The secondary article notes that the recent correction is not a warning sign but a “overdue” breather after such a dramatic run.

SLS009: Building a Second Pillar

While GPS dominates the headlines, Sellas is quietly strengthening its position with SLS009 (Tambiciclib), a selective CDK9 inhibitor licensed from GenFleet Therapeutics. The ongoing study combines SLS009 with two established drugs: Venetoclax (from AbbVie) and Azacitidin (from Bristol Myers Squibb). The combination is being tested in high?risk AML patients whose disease has returned after or failed to respond to a Venetoclax?based regimen. Approximately 160 patients are enrolled, and top?line data are expected by the end of 2026.

This diversification is strategically important. It transforms Sellas from a binary bet on a single Phase 3 readout into a platform with multiple shots on goal. Even so, the near?term volatility remains extreme — the annualised 30?day swing of 127.1% leaves the stock firmly in the territory of strong?nerved investors.

What Comes Next

Analysts see a consensus price target of €15.33, implying 35.6% upside from current levels. That institutional confidence suggests the recent pullback is being viewed as a consolidation rather than a trend reversal. Key near?term support sits at €11.30. Once Sellas formally announces the 80th event, a quiet period will begin ahead of the top?line results. If the announcement is delayed, the stock is likely to continue oscillating with high amplitude, balancing the year?to?date gain against the imminent binary risk.

For now, the company remains a study in contrasts: a 500%?plus rally that still hangs on the outcome of two unseen patient events, backed by a pipeline that is broader than many investors realise.