Cellectis (NASDAQ: CLLS) highlights lasme-cel and eti-cel data for EHA 2026

Rhea-AI Filing Summary

Cellectis, a clinical-stage gene-editing company, announced that new clinical data on its allogeneic CAR-T candidates lasme-cel and eti-cel will be presented at the EHA 2026 congress in Stockholm. An oral presentation will cover full Phase 1 BALLI-01 results in relapsed or refractory B-cell acute lymphoblastic leukemia, which support a pivotal Phase 2 program now recruiting in Europe and North America. A poster will present preliminary Phase 1 NATHALI-01 data in relapsed or refractory B-cell non-Hodgkin lymphoma, exploring how alemtuzumab exposure and cytokine dynamics relate to expansion and response of the dual-targeting CD20/CD22 product. Interim BALLI-01 Phase 2 data and Phase 1 NATHALI-01 clinical data are planned to be disclosed in Q4 2026.

Key Figures

EHA 2026 dates: June 11–14, 2026 BALLI-01 oral session time: June 13, 5:15–6:30 pm CET NATHALI-01 poster time: June 13, 6:45–7:45 pm CET +3 more

6 metrics

EHA 2026 dates June 11–14, 2026 European Hematology Association annual congress in Stockholm

BALLI-01 oral session time June 13, 5:15–6:30 pm CET Lasme-cel Phase 1 BALLI-01 oral presentation slot at EHA 2026

NATHALI-01 poster time June 13, 6:45–7:45 pm CET Eti-cel Phase 1 NATHALI-01 poster presentation slot at EHA 2026

Website posting time June 11, 2026, 8 am CET EHA 2026 presentations to be available on Cellectis’ website

BALLI-01 interim data timing Q4 2026 Interim analysis from pivotal Phase 2 BALLI-01 planned disclosure

NATHALI-01 Phase 1 data timing Q4 2026 Phase 1 clinical data from NATHALI-01 planned disclosure

Key Terms

allogeneic CAR-T, pivotal Phase 2, relapsed or refractory, lymphodepletion regimen, +1 more

5 terms

allogeneic CAR-T medical

"a CD22 directed allogeneic CAR-T, in heavily pretreated patients"

Allogeneic CAR‑T is a type of cancer therapy made from immune cells taken from a donor, genetically modified to recognize and kill cancer cells, and then given to unrelated patients like an off‑the‑shelf medicine. Investors care because it promises faster, cheaper manufacturing and wider patient reach than personalized (autologous) CAR‑T, but its commercial value depends on safety, effectiveness, regulatory approval and the ability to scale production reliably.

pivotal Phase 2 medical

"They form the basis for the pivotal Phase 2 program which is currently recruiting"

A pivotal phase 2 is a mid-stage clinical trial intentionally designed to provide the decisive evidence needed to judge whether a new drug or treatment works and is safe enough to advance toward regulatory approval or larger trials. Think of it as a detailed dress rehearsal: it tests the key questions investors care about — does the treatment benefit patients and have an acceptable risk — and its results can strongly influence a company’s value and next financing or development steps.

relapsed or refractory medical

"in heavily pretreated patients with relapsed or refractory CD22+ B-cell acute lymphoblastic leukemia"

"Relapsed or refractory" describes a situation where a disease, such as an illness or condition, returns after treatment or does not respond to initial treatment efforts. For investors, this indicates ongoing challenges or setbacks in managing the disease, which can affect the success of related treatments or therapies and impact the potential value of associated companies or products. Understanding this helps gauge the stability and future prospects of medical developments or healthcare investments.

lymphodepletion regimen medical

"optimization of the lymphodepletion regimen for this best-in-class dual-targeting CD20/CD22"

A lymphodepletion regimen is a short course of drugs or low-dose radiation given before a cellular immunotherapy to lower a patient’s existing white blood cells and immune activity, creating room for the infused engineered cells to expand and act. For investors it matters because the regimen strongly influences a therapy’s safety, effectiveness, patient eligibility, trial outcomes, logistics and cost — like preparing soil before planting, it helps determine whether the treatment can take root and succeed commercially.

dual-targeting CD20/CD22 medical

"best-in-class dual-targeting CD20/CD22 allogeneic CAR T-cell product"

Form 6-K: How Foreign Companies Report to the SEC →

UNITED STATES
SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

Form 6-K

REPORT OF FOREIGN PRIVATE ISSUER PURSUANT TO RULE 13a-16 OR 15d-16 UNDER THE SECURITIES EXCHANGE ACT OF 1934

Date of Report: May 12, 2026

Commission File Number: 001-36891

Cellectis S.A.
(Exact Name of registrant as specified in its charter)

8, rue de la Croix Jarry
75013 Paris, France
+33 1 81 69 16 00
(Address of principal executive office)

Indicate by check mark whether the registrant files or will file annual reports under cover of Form 20-F or Form 40-F.
Form 20-F [ X ]      Form 40-F [   ]

EXHIBIT INDEX

Exhibit		Title
99.1		Press Release dated May 12, 2026

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned, thereunto duly authorized.

		Cellectis S.A.
		(Registrant)
Date: May 12, 2026		/s/ André Choulika
		André Choulika
		Chief Executive Officer

EXHIBIT 99.1

Cellectis to Present Clinical Data on Lasme-cel and Eti-cel at EHA 2026 Annual Congress

NEW YORK, May 12, 2026 (GLOBE NEWSWIRE) -- Cellectis (the “Company”) (Euronext Growth: ALCLS - NASDAQ: CLLS), a clinical-stage biotechnology company using its pioneering gene editing platform to develop life-saving cell and gene therapies, today announced upcoming presentations on the BALLI-01 and NATHALI-01 clinical trials, at the European Hematology Association (EHA) annual congress, on June 11-14, 2026, in Stockholm, Sweden.

Lasme-cel – Oral Presentation

The abstract reporting the full Phase 1 dataset from the BALLI-01 clinical trial evaluating lasme-cel, a CD22 directed allogeneic CAR-T, in heavily pretreated patients with relapsed or refractory CD22+ B-cell acute lymphoblastic leukemia (r/r B-ALL), has been selected for oral presentation.

These data, which will be presented by Nitin Jain, M.D., Professor of Medicine, Department of Leukemia at MD Anderson Cancer Center in Houston (TX), highlight the promising safety profile and response rates in patients who have relapsed following multiple prior targeted therapies including autologous CD19 CAR-T. They form the basis for the pivotal Phase 2 program which is currently recruiting in Europe and North America.

"We are delighted to present these important data at EHA. The patients in the BALLI-01 trial had largely exhausted treatment options and faced a very poor prognosis. The depth of response we observed offers hope for these patients and demonstrates the potential for lasme-cel to become an effective therapeutic option for those with the highest unmet need. We are pursuing our pivotal Phase 2 program and plan to share the first interim analysis later this year," said Adrian Kilcoyne, M.D., MPH, MBA, Chief Medical Officer at Cellectis.

The BALLI-01 trial is currently recruiting in Pivotal Phase 2 with interim data expected to be disclosed in Q4 2026.

Oral Presentation: Safety and efficacy of UCART22 in heavily pre-treated patients with relapsed or refractory CD22+ B-cell acute lymphoblastic leukemia (B-ALL): results of the Phase 1 BALLI-01 trial

Presenter: Nitin Jain, M.D., Professor of Medicine, Department of Leukemia, University of Texas MD Anderson Cancer Center, Houston (TX)
Session Title: Advances in the treatment of lymphoblastic leukemia
Session Room: K1
Live Session Date and Time: Saturday, June 13 at 5:15 – 6:30pm CET

Eti-cel – Poster Presentation

The abstract from the Phase 1 NATHALI-01 study evaluating eti-cel in patients with relapsed or refractory B-cell non-Hodgkin lymphoma (r/r B-NHL) has been accepted for poster presentation. This preliminary analysis explores the relationship between alemtuzumab exposure, eti-cel cellular expansion, cytokine dynamics, and clinical outcomes, providing early mechanistic insights into the optimization of the lymphodepletion regimen for this best-in-class dual-targeting CD20/CD22 allogeneic CAR T-cell product.

The Phase 1 clinical data of the NATHALI-01 clinical trial are planned to be disclosed in Q4 2026.

Poster Presentation: Alemtuzumab exposure and sustained IL-2 drive UCART20x22 expansion and clinical response in adults with relapsed or refractory B-cell non-Hodgkin lymphoma: NATHALI-01 study

Presenter: Professor Emmanuel Bachy, M.D., Ph.D., Department of Clinical Hematology, Lyon Sud Hospital, Lyon, France.
Session: Poster Session 2
Poster Number: 4758
Session Date and Time: Saturday, June 13 at 6:45 - 7:45pm CET

The abstracts are published on the EHA website. The presentations will be available on Cellectis’ website on June 11, 2026, at 8 am CET.

About Cellectis     
Cellectis is a clinical-stage biotechnology company using its pioneering gene-editing platform to develop life-saving cell and gene therapies. The company utilizes an allogeneic approach for CAR T immunotherapies in oncology, pioneering the concept of off-the-shelf and ready-to-use gene-edited CAR T-cells to treat cancer patients, and a platform to develop gene therapies in other therapeutic indications. With its in-house manufacturing capabilities, Cellectis is one of the few end-to-end gene editing companies that controls the cell and gene therapy value chain from start to finish.     
    
Cellectis’ headquarters are in Paris, France, with locations in New York and Raleigh, NC. Cellectis is listed on the Nasdaq Global Market (ticker: CLLS) and on Euronext Growth (ticker: ALCLS). To find out more, visit www.cellectis.com and follow Cellectis on LinkedIn and X.  

Cautionary Statement 

This press release contains “forward-looking” statements within the meaning of applicable securities laws, including the Private Securities Litigation Reform Act of 1995. Forward-looking statements may be identified by words such as “become,” “expected,” “ ‘plan,” “planned,” “potential,” or “will” or the negative of these and similar expressions. These forward-looking statements are based on our management’s current expectations and assumptions and on information currently available to management. Forward-looking statements include statements about the potential of the pivotal Phase 2 BALLI-01 trial to be a registrational phase, the advancement, timing and progress of clinical trials (including with respect to patient enrollment and follow-up), the timing of our presentations of data and submissions of regulatory filings the potential benefit of our product candidates and technologies. These forward-looking statements are made in light of information currently available to us and are subject to significant risks and uncertainties, including with respect to the numerous risks associated with biopharmaceutical product candidate development. Among these are significant risks that the BALLI-01 Phase 1 data may not be validated by data from later stage of clinical trials and that our product candidate may not receive regulatory approval for commercialization. Particular caution should be exercised when interpreting results from Phase 1 studies and results relating to a small number of patients – such results should not be viewed as predictive of future results. With respect to our cash runway, our operating plans, including product development plans, may change as a result of various factors, including factors currently unknown to us. Furthermore, many other important factors, including those described in our Annual Report on Form 20-F as amended and in our annual financial report (including the management report) for the year ended December 31, 2025 and subsequent filings Cellectis makes with the Securities Exchange Commission from time to time, which are available on the SEC’s website at www.sec.gov, as well as other known and unknown risks and uncertainties may adversely affect such forward-looking statements and cause our actual results, performance or achievements to be materially different from those expressed or implied by the forward-looking statements. Except as required by law, we assume no obligation to update these forward-looking statements publicly, or to update the reasons why actual results could differ materially from those anticipated in the forward-looking statements, even if new information becomes available in the future.   

For further information on Cellectis, please contact:         
     
Media contacts:              
Pascalyne Wilson, Director, Communications, + 33 (0)7 76 99 14 33, media@cellectis.com         

Patricia Sosa Navarro, Chief of Staff to the CEO, +33 (0)7 76 77 46 93      

Investor Relations contact:           
Arthur Stril, Chief Financial Officer & Chief Business Officer, investors@cellectis.com

Attachment

• 20260512_EHA PR (https://ml.globenewswire.com/Resource/Download/73b07596-c9e6-4814-9078-084c0f0bf9f3)

FAQ

What did Cellectis (CLLS) announce in its May 2026 Form 6-K?

Cellectis announced upcoming presentations of clinical data for its CAR-T product candidates lasme-cel and eti-cel at the EHA 2026 congress. The update highlights Phase 1 BALLI-01 and NATHALI-01 trial results and outlines plans to disclose additional clinical data in Q4 2026.

What is lasme-cel in Cellectis’ BALLI-01 trial and who are the patients?

Lasme-cel is a CD22-directed allogeneic CAR-T therapy studied in the BALLI-01 trial for heavily pretreated relapsed or refractory CD22+ B-cell acute lymphoblastic leukemia. Patients in this trial have received multiple prior targeted therapies, including autologous CD19 CAR-T, and generally face poor prognoses.

What milestones did Cellectis disclose for the BALLI-01 pivotal Phase 2 program?

Cellectis reported that the BALLI-01 program has progressed into a pivotal Phase 2 trial currently recruiting patients in Europe and North America. The company plans to share the first interim analysis from this Phase 2 study in Q4 2026, following the Phase 1 oral presentation at EHA 2026.

What is eti-cel and what does the NATHALI-01 study evaluate for Cellectis?

Eti-cel is a dual-targeting CD20/CD22 allogeneic CAR-T product candidate evaluated in the Phase 1 NATHALI-01 study for relapsed or refractory B-cell non-Hodgkin lymphoma. The preliminary analysis examines how alemtuzumab exposure, eti-cel expansion, cytokine dynamics, and clinical outcomes interact to optimize lymphodepletion.

When and where will Cellectis present its EHA 2026 clinical data?

Cellectis’ EHA 2026 presentations take place June 11–14, 2026, in Stockholm, Sweden. The BALLI-01 lasme-cel oral session is scheduled for Saturday, June 13, 5:15–6:30 pm CET, with the eti-cel NATHALI-01 poster session later that evening from 6:45–7:45 pm CET.

When will Cellectis publish the EHA presentations and further trial data?

Cellectis plans to post the EHA 2026 presentations on its website on June 11, 2026, at 8 am CET. The company also plans to disclose interim BALLI-01 Phase 2 data and Phase 1 NATHALI-01 clinical data during Q4 2026, according to the announcement.

Filing Exhibits & Attachments

1 document

Press Releases

• EX-99.1 PRESS RELEASE 9.6 KB