Cellectis Reports Clinical Hold Placed on MELANI-01 Study

July 6, 2020 – New York (N.Y.) – Cellectis (Euronext Growth: ALCLS - Nasdaq: CLLS), a biopharmaceutical company focused on developing immunotherapies based on gene-edited allogeneic CAR T-cells (UCART), today announced that the MELANI-01 trial has been placed on clinical hold by the U.S. Food and Drug Administration (FDA). 

This clinical hold which impacts one of the three Cellectis product candidates currently in clinical studies, was initiated following the submission of a safety report regarding one patient enrolled in the MELANI-01 study at dose level two (DL2), with relapsed and refractory multiple myeloma. This patient, who had been treated unsuccessfully, prior to enrollment with numerous lines of prior therapy, including autologous CAR T-cells, experienced a fatal treatment-emergent adverse event of cardiac arrest. Clinical evaluation of the case remains ongoing and additional details as to the immediate and underlying causes of this event are being collected.

Of note, prior to the clinical hold being issued by the FDA, Cellectis had decided to expand enrollment at DL1, which may be the appropriate dose for further evaluation in the expansion portion of the trial and potentially the recommended Phase 2 dose based on an assessment of the preliminary clinical and translational data. The Company had begun executing updates to the clinical protocol to reflect this as well as to monitor and mitigate for additional potential risks given its novel mechanism of action.

“We share the FDA’s commitment to patient safety and are working collaboratively with the agency and the investigators to resolve this clinical hold,” said Carrie Brownstein, MD, Chief Medical Officer, Cellectis. “The safety of patients enrolled in our clinical trials is our utmost priority and we at Cellectis remain committed to safely resuming the clinical development of UCART product candidate targeting CS1 for patients with multiple myeloma and unmet medical need.”

Cellectis is working closely with the FDA to address the agency’s requests including changes to the MELANI-01 clinical protocol designed to enhance patient safety, and expect to submit requested information including an amended protocol in due course.

Patient enrollment is ongoing in our two other proprietary Phase 1 dose escalation trials: AMELI-01 evaluating UCART123 in relapsed and refractory acute myeloid leukemia and BALLI-01 evaluating UCART22 in relapsed and refractory B-cell acute lymphoblastic leukemia.

About MELANI-01

MELANI-01 is a Phase 1 open-label First-In-Human dose escalation clinical study evaluating UCARTCS1A product candidate for the treatment of patients with relapsed or refractory multiple myeloma (MM). UCARTCS1A is an allogeneic, off-the-shelf, gene-edited T-cell product candidate designed for the treatment of CS1/SLAMF7-expressing hematologic malignancies. CS1 (SLAMF7) is highly expressed on MM tumor cells.

About Multiple Myeloma (MM)

Multiple myeloma is a cancer that affects a type of white blood cells called plasma cells that are specialized mature B-cells, which secrete antibodies to combat infections. Multiple myeloma is characterized by the uncontrolled proliferation of neoplastic plasma cells in the bone marrow, where they overcrowd healthy blood cells. Although MM is a chronic disease and an exact cause has not yet been identified, researchers have made significant progress over the years in managing the disease through better understanding MM’s pathophysiology. The progress in finding a cure needs to be continued as The American Cancer Society estimates that 32,110 new cases of MM will be diagnosed, and 12,960 deaths are expected to occur in 2019 in the U.S. alone.