SELLAS Life Sciences Group, Inc.

The Company expects its cash and cash equivalents will be sufficient to fund its current planned operations for at least the next twelve months from the date of issuance of these consolidated financial statements, although the Company may pursue additional capital resources through public or private equity or debt financings or by entering into additional license agreements or collaborations with other companies.

SEC original ↗SELLAS Life Sciences Group, Inc. — 10-Q Quarterly report10-QAug 11, 2026

The weighted average assumptions used during the three and six months ended June 30, 2026 and 2025, were as follows: Three Months Ended June 30, Six Months Ended June 30, 2026 2025 2026 2025 Risk free interest rate n/a n/a n/a 4.25 % Volatility n/a n/a n/a 122.43 % Expected term (years) n/a n/a n/a 6.17 Expected dividend yield n/a n/a n/a % There were no options granted during each of the three months ended June 30, 2026 and 2025, and no options granted during the six months ended June 30, 2026.

SEC original ↗SELLAS Life Sciences Group, Inc. — 10-Q Quarterly report10-QAug 11, 2026

The dividend yield assumption is zero because the Company has never paid cash dividends and presently has no intention to do so.

SEC original ↗SELLAS Life Sciences Group, Inc. — 10-Q Quarterly report10-QAug 11, 2026

(NASDAQ SLS) ( SELLAS or the Company ), a late-stage clinical biopharmaceutical company focused on the development of novel therapies for a broad range of cancer indications, today reported financial results for the second quarter ended June 30, 2025, and provided a corporate update.

SEC original ↗SELLAS Life Sciences Group, Inc. — Earnings release (8-K exhibit)EX-99Aug 12, 2025

We are now preparing an 80-patient trial that is focused on newly diagnosed and early refractory to venetoclax and azacitidine AML patients, with enrollment anticipated to begin by Q1 2026.

SEC original ↗SELLAS Life Sciences Group, Inc. — Earnings release (8-K exhibit)EX-99Aug 12, 2025

With the final pivotal Phase 3 REGAL data of GPS in AML expected by year-end, positive Phase 2 data of SLS009 in r r AML, and our upcoming ESMO presentation showcasing SLS009 s impact in T-PLL, we enter the second half of 2025 with tremendous momentum and a clear focus on advancing our late-stage clinical programs and growing shareholder value.

SEC original ↗SELLAS Life Sciences Group, Inc. — Earnings release (8-K exhibit)EX-99Aug 12, 2025

Whether additional patients will be needed either for broader study expansion or only within one of the study arms will depend on the outcomes observed in the initial cohorts (n 40 per arm).

SEC original ↗SELLAS Life Sciences Group, Inc. — Earnings release (8-K exhibit)EX-99Aug 12, 2025

Amrein, MD, Alex Kentsis, MD, PhD, and Linghua Wang, MD, PhD, bring decades of expertise in cancer research, clinical oncology, and translational medicine, further strengthening the Company s strategic guidance as it advances its pipeline.

SEC original ↗SELLAS Life Sciences Group, Inc. — Earnings release (8-K exhibit)EX-99Aug 12, 2025

These forward-looking statements are based on current plans, objectives, estimates, expectations, and intentions, and inherently involve significant risks and uncertainties.

SEC original ↗SELLAS Life Sciences Group, Inc. — Earnings release (8-K exhibit)EX-99Aug 12, 2025

Actual results and the timing of events could differ materially from those anticipated in such forward-looking statements as a result of these risks and uncertainties, which include, without limitation, risks and uncertainties with oncology product development and clinical success thereof, the uncertainty of regulatory approval, and other risks and uncertainties affecting SELLAS and its development programs as set forth under the caption Risk Factors in SELLAS Annual Report on Form 10-K filed on March 20, 2025 and in its other SEC filings.

SEC original ↗SELLAS Life Sciences Group, Inc. — Earnings release (8-K exhibit)EX-99Aug 12, 2025

Other risks and uncertainties of which SELLAS is not currently aware may also affect SELLAS forward-looking statements and may cause actual results and the timing of events to differ materially from those anticipated.

SEC original ↗SELLAS Life Sciences Group, Inc. — Earnings release (8-K exhibit)EX-99Aug 12, 2025

Forward-looking statements are subject to inherent uncertainties, risks and changes in circumstances that are difficult to predict and many of which are outside of our control.

SEC original ↗SELLAS Life Sciences Group, Inc. — 10-Q Quarterly report10-QAug 11, 2026

Given these risks and uncertainties, you should not place undue reliance on these forward-looking statements.

SEC original ↗SELLAS Life Sciences Group, Inc. — 10-Q Quarterly report10-QAug 11, 2026

These factors include, but are not limited to, those factors set forth in the sections captioned "Business Overview, Risk Factors, Legal Proceedings, and Management s Discussion and Analysis of Financial Condition and Results of Operations, in this Quarterly Report on Form 10-Q, in our Annual Report on Form 10-K for the year ended December 31, 2025 as filed with the Securities and Exchange Commission ("SEC") on March 19, 2026 ("2025 Annual Report") and in our other public filings with the SEC, all of which you should review carefully.

SEC original ↗SELLAS Life Sciences Group, Inc. — 10-Q Quarterly report10-QAug 11, 2026