SELLAS Life Sciences (SLS): Haverhill Research Report

Haverhill Financial Research · Published October 10, 2026

SELLAS is a $2.5 billion bet on one leukemia trial that could read out any week. If the Phase 3 REGAL trial works, the company has a real product; if it fails, we think the shares are worth about $1.40. Weighing both outcomes, our 12-month price target of $7 (through October 2027) sits about 40% below the $11.65 close, so we rate the shares Sell.

Our thesis: REGAL has a fair chance of working, but even a win opens a small market, and the share price already pays for a large one.

What we like. REGAL is testing galinpepimut-S (GPS), a vaccine against the WT1 protein found on most leukemia cells, in patients who have just reached a second remission. That group has no standard treatment beyond watching and waiting or low-intensity chemotherapy, and usually lives six to eight months. The trial cleared its interim futility test in January 2025, and blinded survival across both arms was above 12 months at that point. Few small-cap biotechs reach a Phase 3 readout with that much support behind them.

What the market may be missing. The approved use, if REGAL works, would cover only about 1,900 US patients a year by our count. Even at a premium price, that supports peak sales in the hundreds of millions, not billions. A $2.5 billion valuation needs the drug to move into earlier lines of treatment, which would take another trial and several years.

What holds us back. The readout is binary and close, so a miss would erase most of the value in a day. Blinded data also cannot tell us whether GPS is working or the trial simply enrolled healthier patients. And the final analysis has only 80 deaths behind it, which means GPS needs a large survival benefit to reach statistical significance.

Today it doesn't: SELLAS has no product revenue and funds itself by selling shares. If REGAL succeeds, money would come from one product sold into one narrow slot in leukemia care.

What it would sell. GPS is a course of about 15 injections given over roughly a year, starting once a patient is in remission. It is meant to train the immune system to find the few leukemia cells that survive chemotherapy, which is what causes relapse. SELLAS licenses GPS from Memorial Sloan Kettering Cancer Center.

Who would pay. Hospitals and oncology practices would buy it, and insurers would reimburse it. With a median age at diagnosis near 69, Medicare would be the main payer, so the price would need to hold up in Medicare's drug reviews.

Why they would keep paying. Each patient buys one course, so revenue depends on a steady flow of new patients rather than repeat use. The case for paying is that no drug is approved to keep these patients in remission. That gives GPS a clear spot if it works, but not a large one.

At a $250,000 course and half of eligible patients treated, the US label is worth about $240 million a year at peak. Adding Europe and Japan through a partner takes our base case to about $400 million worldwide.

The second product. SLS009 (tambiciclib) is a pill that blocks CDK9, a protein leukemia cells use to resist the standard azacitidine-plus-venetoclax regimen. SELLAS licenses it from GenFleet Therapeutics. In 35 patients with hard-to-treat relapsed AML, adding it produced a 46% response rate with no dose-limiting side effects. A frontline trial has enrolled 28 of a planned 80 patients and reports topline data in Q4 2026.

The pipeline at a glance. GPS (galinpepimut-S), the WT1 peptide vaccine, is in the Phase 3 REGAL trial for AML patients in second remission who are not going to transplant; enrollment closed in Q1 2024 and topline comes after the 80th death. SLS009 (tambiciclib), the oral CDK9 inhibitor, is in a Phase 2 trial in newly diagnosed AML alongside azacitidine and venetoclax, with 28 of 80 patients enrolled and topline due in Q4 2026. SLS009 is also preclinical in pancreatic cancer with RAS inhibitors, where an academic-led trial is planned.

REGAL's final analysis starts once 80 patients have died, and the last count SELLAS gave was 78, on May 11, 2026. Everything in this report turns on what that analysis shows.

The design. REGAL randomly assigns patients 1:1 to GPS or to their doctor's choice of best available treatment (watchful waiting, a hypomethylating drug, venetoclax or low-dose cytarabine). All are in a second remission after salvage chemotherapy and are not going to transplant. The only primary endpoint is overall survival. Enrollment closed in Q1 2024.

What the blinded data shows. At the January 2025 interim, fewer than half of patients had died, and median survival across both arms was above 12 months against about 6 months expected. In a random sample, 80% of GPS patients mounted an immune response to WT1. SELLAS has repeated since then that survival "appears longer than expected."

Deaths ran at about one a month through May, then the count went quiet. The long wait for the last two deaths cuts both ways. If GPS works, its patients should be living longer, so the final deaths would arrive slowly. But slow pooled deaths can also mean both arms enrolled healthier patients than the trial assumed, and blinded data cannot separate the two.

The statistical bar. Eighty deaths is a small final analysis for a survival trial. Using the standard approximation for a 1:1 trial, GPS needs a hazard ratio of about 0.65 or lower to be significant, meaning roughly a third lower risk of death at any point. The interim look spent part of the trial's error budget, so the real bar is slightly stricter.

GPS's earlier Phase 2 study showed a far larger gap, 21.0 months against 5.4 months, but it was small and not randomized. Our base case assumes REGAL lands between those two marks: good enough to win, not good enough to match Phase 2.

SELLAS has no revenue, spends about $10 million a quarter and has paid for it by issuing shares. The balance sheet is the strongest it has been, but shareholders have been diluted heavily along the way.

Losses are small for a Phase 3 company. Net loss was $18.0 million in the first half of 2026 and $26.9 million for all of 2025. Cash used in operations was $16.4 million in the first half, about $8 million a quarter. The rise in R&D is mostly drug manufacturing and regulatory work for a possible approval filing, which SELLAS is paying for before it knows the result.

No debt, and cash for well over a year. Cash was $138.3 million on June 30, 2026, against total liabilities of $7.7 million. SELLAS says that covers at least the next 12 months; at the current burn it would last about four years. A launch would change that quickly.

The dilution behind the cash. Investors exercised warrants for $67.2 million in 2025 and another $82.9 million in the first half of 2026, mostly at $1.41 to $2.00 a share. In March 2026 SELLAS also set up a $150 million at-the-market program with TD Cowen, which lets it sell new shares into the market at any time; none had been sold by August. Counting the 9.7 million warrants, 2.6 million options and 3.3 million restricted shares still outstanding, we put the fully diluted count at about 218 million.

Check the figures: Q2 2026 Form 10-Q · Q1 2026 Form 10-Q · Q2 2026 results · Full-year 2025 results · Q3 2025 results

GPS would face no direct rival in its exact slot, but it would compete for the same patients with cheaper, familiar drugs and with a fast-growing set of targeted pills.

Who it competes with. Low-intensity chemotherapy, azacitidine or decitabine with or without venetoclax, is what most older patients in remission get today; it is REGAL's comparator, so GPS must beat it on survival. Targeted pills against FLT3, IDH1, IDH2 and menin help only patients carrying those mutations, while GPS works regardless of mutation because most AML carries WT1. Oral azacitidine is used as maintenance after a first remission, a label GPS would need a new trial to reach. Donor stem cell transplants suit younger, fitter patients and were excluded from REGAL; GPS is aimed at those who cannot go to transplant.

Where the moat is real. If approved, GPS would be the only drug labeled for keeping second-remission AML patients alive, and it is mutation-agnostic. It is a vaccine with mild side effects, which matters for patients averaging nearly 70.

Where it is thin. Doctors already reach for azacitidine and venetoclax in this setting, and those are cheap and familiar. Targeted pills keep moving earlier in treatment, which could shrink the pool of patients who reach a second remission at all. And a peptide vaccine is not hard to copy once the WT1 approach is proven.

Management and governance. CEO Angelos Stergiou founded SELLAS and has run it since its 2017 combination with Galena Biopharma. The company is small, with a board and management team built around one program. In July 2026 an arbitrator dismissed SELLAS's claims against 3D Medicines, which licensed GPS rights in Greater China; SELLAS accrued about $1.0 million for fees it must pay. That leaves the China partnership's value uncertain.

We value SELLAS at $7 per share over the next 12 months (to October 2027), a probability-weighted blend of three REGAL outcomes. That is about 40% below the $11.65 close, which supports a Sell.

Our method. SELLAS has no earnings or sales to value, so we value each trial outcome and weight them by our odds:

If REGAL misses, GPS is worth nothing in our model, and the shares are worth cash plus SLS009.

Why these numbers. A 45% chance of a miss is better odds than the typical Phase 3 cancer trial, reflecting the clean interim and long pooled survival. Our base peak sales of $400 million assume a $250,000 course, half of the ~1,900 eligible US patients treated, and a partner in Europe and Japan. The clean-win case adds a move into first remission, which would need another trial but is a much larger group.

What the price implies. The odds matter more than any other input. If the chance of a miss fell from 45% to 30%, with the difference going to a modest win, our value would rise only to about $7.80. Holding our win and miss values fixed, $11.65 implies about a 99% chance REGAL succeeds. Put another way, the market is pricing the outcome as close to certain, when the honest answer is closer to a coin flip.

Today's valuation, for reference. At $11.65, diluted equity is worth about $2.5 billion, or about $2.4 billion after cash and exercise proceeds. That is roughly six times our base-case peak sales for a drug that is not yet approved.

The biggest risk is simple: REGAL misses and the shares fall toward cash. We rank the rest by how much they would move our value per share.

Risks 1 and 2 decide most of the gap between our cases, and both resolve within about a year.

Our Sell rests on one idea: the market prices a near-certain win, and even a win opens a market too small for today's valuation. These are the specific signals that would prove that wrong in either direction.

Signals that would move us to Hold or Buy

Signals that would make us more bearish

The next big test is the 80th REGAL death, which SELLAS will announce when it happens; topline results should follow within weeks.

Every company figure in this report comes from SELLAS's own filings and releases, linked below. The analysis, model and price target are Haverhill Financial Research's own work.

Disclosures. Haverhill Financial Research is a publisher of general financial commentary. This report is not personalized investment advice and does not consider any reader's financial situation; readers should do their own research. Price targets are estimates of value, not guarantees, and clinical-stage biotech stocks can lose most of their value on a single trial result. The author of this post does not hold a position in SLS. Data as of October 9, 2026.