SELLAS reported on 12 May 2026 that its CRO had counted 78 of the 80 pre-specified death events needed to trigger final analysis of Phase 3 REGAL, a survival-driven trial of galinpepimut-S, or GPS, in AML patients in complete remission after second-line salvage therapy (SELLAS Q1 2026 update, SEC exhibit).

The key discrepancy is timing, SELLAS said on 23 Jan 2025 that it anticipated reaching 80 events in 2025, but as of 11 May 2026 the study remained at 78 events, still blinded to outcomes (SELLAS interim-analysis release, SELLAS Q1 2026 update). I privilege the May 2026 company filing and SEC exhibit for current event count, and the Jan 2025 release for the original expectation.

60-second thesis frame

The diligence question is not whether REGAL is “near data”, it is whether a small-cap, event-driven, open-label Phase 3 in a narrow post-salvage AML maintenance population can convert a slow event curve into a clean overall-survival win, a credible regulatory package, and a reimbursable product. Confidence rises if the final analysis shows a statistically robust OS effect, tolerable safety, balanced censoring, and consistency across MRD, cytogenetic-risk, and CR-duration strata. Confidence falls if the delayed 80th event reflects noise, informative censoring, site heterogeneity, or a BAT arm that performs better than historical assumptions. The interim readout cleared futility, efficacy, and safety review at 60 deaths, but no arm-level efficacy data were unblinded publicly, so the upcoming 80-event analysis remains the core binary risk (SELLAS interim-analysis release, Targeted Oncology, REGAL protocol paper).

The seven diligence questions

Clinical

• Does REGAL hit overall survival at the final 80-event analysis with a hazard ratio and p-value that remain persuasive after scrutinizing censoring, follow-up imbalance, and post-progression therapies?
• Are the efficacy signals consistent across CR2 versus CRp2, MRD status, cytogenetic risk, and duration of first remission, rather than concentrated in one small subgroup?

Payer or Access

• If positive, will payers view GPS as a differentiated maintenance option for transplant-ineligible AML patients in second remission, or as a niche vaccine with uncertain durability versus lower-cost observation, HMAs, venetoclax-based approaches, or low-dose cytarabine? REGAL’s BAT options include observation, hypomethylating agents, venetoclax, and/or low-dose cytarabine (REGAL protocol paper, Targeted Oncology).
• What real-world testing and documentation will be required, especially around remission status, transplant ineligibility, MRD, WT1 rationale, and prior salvage therapy?

Ops or Adoption

• Can SELLAS manufacture, release, and commercially support an immunotherapy product quickly enough if the readout is positive, given Q1 2026 R&D spend already rose partly from manufacturing, clinical, and regulatory consulting costs tied to a potential BLA package (SEC exhibit)?

Competitive

• Would a REGAL win remain clinically relevant as AML treatment shifts earlier toward venetoclax combinations, targeted agents, MRD-guided strategies, and transplant optimization?

Team or Cap table

• Is the strengthened balance sheet enough to carry BLA preparation, potential launch build, and SLS009 development without dilutive financing pressure? SELLAS reported $107.1 million in cash and equivalents at 31 Mar 2026, $7.5 million in post-quarter warrant proceeds, and a $150 million ATM facility with no sales to date (SELLAS Q1 2026 update, SEC exhibit).

Red flags

• Final OS misses statistical significance, or the effect is fragile after censoring, stratification, or sensitivity analyses.
• The BAT arm outperforms historical expectations, weakening the comparison to prior 6-month median survival assumptions cited around the interim update (SELLAS interim-analysis release, CancerNetwork).
• The slow path from expected 2025 event completion to 78 events as of 11 May 2026 turns out to reflect trial conduct complexity rather than durable benefit (SELLAS interim-analysis release, SELLAS Q1 2026 update).

Next catalyst

REGAL final analysis after the 80th death event, followed by database lock, blinded data review, statistical analysis, unblinding, and topline disclosure, with the latest public count at 78 events on 11 May 2026 (SELLAS Q1 2026 update, SEC exhibit).

FAQ

What exactly changed in SELLAS Life Sciences’ REGAL AML update on 12 May 2026, and why does it matter?

SELLAS said the CRO for REGAL had counted 78 of the 80 pre-specified death events needed to trigger the final Phase 3 analysis, while the company remained blinded to trial outcomes (SELLAS Q1 2026 update). This matters because the next two events start the process toward database lock, unblinding, and topline data in a small-cap, late-stage AML program.

What is REGAL testing after SELLAS’ 12 May 2026 update?

REGAL is testing galinpepimut-S, a WT1-targeting peptide immunotherapy, as maintenance therapy versus investigator’s choice of best available therapy in AML patients who achieved complete remission after second-line salvage therapy (REGAL protocol paper, Targeted Oncology). The trial is survival-driven, so the investment and clinical question centers on overall survival rather than response rate.

Why did investors focus on timing after SELLAS’ 12 May 2026 REGAL AML update?

SELLAS said in Jan 2025 that the final analysis would occur once 80 events were reached and anticipated that threshold in 2025, but the company reported 78 events as of 11 May 2026 (SELLAS interim-analysis release, SELLAS Q1 2026 update). The delay can be read bullishly if it reflects longer survival, but it can also reflect statistical or operational complexity, so the final unblinded OS result is the only decisive evidence.

What did the Jan 2025 interim analysis say before the 12 May 2026 update?

The IDMC recommended that REGAL continue without modification after a pre-specified interim analysis at 60 deaths, and SELLAS said the IDMC noted no safety concerns and that GPS exceeded predetermined futility criteria (SELLAS interim-analysis release). Independent oncology coverage reported the same continuation decision, but public disclosures did not include arm-level unblinded efficacy data (CancerNetwork, Targeted Oncology).

How should investors think about SELLAS’ balance sheet after the 12 May 2026 REGAL AML update?

SELLAS reported $107.1 million in cash and equivalents at 31 Mar 2026, plus $7.5 million of additional warrant proceeds after quarter-end (SEC exhibit). That improves runway into the readout, but a positive REGAL result could still require spending on regulatory filing, manufacturing readiness, and commercial planning.

Publisher / Disclosure

Publisher: LucidQuest Ventures Ltd. Produced: 27 May 2026, 13:51 London. Purpose: general and impersonal information. Not investment research or advice, no offer or solicitation, no suitability assessment. UK: directed at investment professionals under Article 19(5) and certain high-net-worth entities under Article 49(2)(a)–(d) of the Financial Promotion Order 2005. Others should not act on this. Sources and accuracy: public sources believed reliable, provided “as is,” may change without notice. No duty to update. Past performance is not reliable. Forward-looking statements carry risks. Methodology: questions-first framework using public sources. No conflicts. Authors do not hold positions unless stated. © 2026 LucidQuest Ventures Ltd.

Entities / Keywords

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