SLS Stock: SELLAS Investors Look For More After 542% Surge

SELLAS Life Sciences Group [SLS] is a late-stage clinical biopharmaceutical company developing cancer treatments. 

Galinpepimut-S (GPS), the company’s lead product candidate, is currently undergoing a Phase 3 trial as a potential maintenance therapy for patients with acute myeloid leukaemia (AML). On 13 May, the SLS share price surged more than 25% after the company indicated that the trial was close to completion.

Adding to investor optimism was market speculation about a potential company buyout. SLS shares hit a five-year high of $15.88 on 30 June.

In this article, we analyse the drivers behind SELLAS’ 542% share price surge over the past year, discuss its financial health, and review bull and bear cases for SLS stock.

Key developments: Road to commercialisation or buyout? 

The Phase 3 trial of GPS in AML maintenance is being managed by a third-party contract research organisation. The clinical trial is event-driven and requires 80 events (deaths) before the final analysis can begin. Until then, SELLAS remains blinded to the trial outcomes.

SELLAS disclosed that 78 of the required 80 events had occurred as of 11 May.

Positive Phase 3 results for GPS in AML could be game-changing for SELLAS, potentially paving the way for the company to seek approval and launch its first commercial drug.

So far investors have had to rely on earlier studies for clues about the drug’s efficacy, where a Phase 2 clinical trial showed that GPS-treated patients had median overall survival of 21 months compared with 5.4 months for those treated with the best available treatment.

In late June, CEO Angelos Stergiou reinforced investor confidence, noting via LinkedIn: “We have reached 78 of the required 80 events. Crucially, the delay in reaching this 80th event is a profoundly positive signal – it suggests patients are living longer than projected. GPS has the potential to become the true standard of care in AML maintenance.”

Optimism over the GPS trial has also fuelled buyout speculation around SELLAS, amid a booming biopharma M&A market.

According to PwC, Q1 2026 was one of the strongest periods for biopharma M&A in recent years, with pharmaceutical and life sciences deal value topping $65bn.

Oncology-focused companies have been among the preferred targets due to the sub-sector’s status as a high-growth therapeutic area with strong margins. Recent examples include Gilead Sciences’ [GILD] $7.8bn deal to acquire clinical-stage cell therapy biotech Arcellx; Eli Lilly’s [LLY] $7bn acquisition of genetic medicines developer Kelonia Therapeutics; and GSK’s [GSK] $10.6bn offer for Nuvalent [NUVL] and its late-stage lung cancer drug candidates.

According to IQVIA, global spending on cancer medicine is expected to rise from $252bn in 2024 to $441bn by 2029.

Against this backdrop, speculators are betting on SELLAS becoming subject to an acquisition bid from larger peers. While there have been no company updates or media reports suggesting M&A activity involving SELLAS at the time of writing, market watchers have chosen to focus on a late-June regulatory filing by SELLAS related to executive severance and change-of-control agreements. 

Published on 24 June, the filing noted board approvals to allow CEO Angelos Stergiou’s severance to be paid as a lump sum. Amendments made to change termination clauses of CFO John Burns and Senior Vice President Dragan Cicic only added to takeover chatter.

SELLAS breaks out in Q2

Over the past year, SLS shares have surged over 542% from about $2.17 to $13.94, as of 6 July.

In the same period, the US equity benchmark S&P 500 index returned 20% and the sectoral Nasdaq Biotechnology index [NBI] increased by about 55%.

In Q2 2026 alone, SLS stock gained about 248%, driven by positive updates on the GPS Phase 3 trial and a wave of speculation around SELLAS as a potential acquisition target.

Key fundamentals and financial health: Pre-revenue, comfortable cash position

SELLAS is a pre-revenue biopharma company and has not reported any product revenue to date.

In FY 2025, the company posted a net loss of $26.86m, narrowing from a net loss of $30.88m in 2024. By the end of 2025, SELLAS had accumulated a deficit of about $275m.

Total operating expenses stood at $28.27m in 2025. Research and development accounted for 56.7% of that figure, with the rest coming from general and administrative expenses.

As of 31 March 2026, SELLAS had $107.1m in cash and cash equivalents. The company also had an at-the-market equity offering facility, giving it the option to raise up to $150m.

Comparing fundamentals: SLS vs IMTX vs CGON

Immatics [IMTX] is a clinical-stage biopharmaceutical company developing cancer treatments using cell therapy technologies. It has no products for commercial sale, although the company has received revenue from collaboration agreements with Moderna [MRNA] and Bristol Myers Squibb [BMY]. The company’s intellectual property portfolio with patents covering advanced cancer immunotherapies, cell therapies, cancer antigen target validation and screening is a key part of its competitive position.

CG Oncology [CGON] is also a late-stage clinical biopharmaceutical company. Its lead drug candidate is Cretostimogene, currently undergoing Phase 3 clinical trial for the treatment of two subsets of patients with non-muscle invasive bladder cancer. The company has no products approved for commercial sale but earns revenue through its contract manufacturing unit Biovire, and via licence and collaboration agreements.

Source: Yahoo Finance

SLS stock: The investment case

The bull case for SELLAS

A positive outcome from GPS’ ongoing Phase 3 trial could give SELLAS a clear regulatory pathway towards FDA approval for GPS as a maintenance therapy for AML patients. If approved and commercialised, GPS could transform SELLAS from a clinical-stage biotech into a revenue-generating biopharma company.

Future cash flows from GPS in AML could also support the development of the drug in other cancer indications, including ovarian cancer, asbestos-related cancer and multiple myeloma.

Beyond GPS, the company is also developing SLS009, or tambiciclib, for lymphomas and a subset of AML patients.

The bear case for SELLAS

Negative Phase 3 trial results will be a major setback because GPS is SELLAS’ lead product candidate and the main driver of the stock’s recent rally. This would not only delay the path to commercialisation, but could also push investors to focus on the company’s earlier-stage programmes, putting pressure on the share price. SELLAS remains dependent on capital markets to fund operations. A lower share price could make future fundraising more difficult and more dilutive.

Risk is exacerbated by SELLAS’ sharp rally over the past year, with upside on successful Phase 3 trials already priced in.

Investors should also note that SELLAS has in-licensed GPS and SLS009 from Memorial Sloan Kettering Cancer Centre and GenFleet Therapeutics [2595:HK], respectively.

Conclusion

SELLAS stock’s trajectory hinges on the outcome of the GPS Phase 3 trial and its path to commercialisation. Speculation around a potential M&A bid is also tied to this outcome, with market watchers hopeful that positive trial results would help SELLAS command a premium should a bid materialise.

CMC Aureon’s proprietary theme relevance system maps the world’s biggest investing megatrends. For in-depth analyses of stocks with high growth potential, subscribe to CMC Aureon Foresight.