On June 3, 2022 Arcellx, Inc. (NASDAQ: ACLX), a biotechnology company reimagining cell therapy through the development of innovative immunotherapies for patients with cancer and other incurable diseases, reported new positive clinical data from the ongoing Phase 1 expansion study of its novel, autologous, CART-ddBCMA therapy for the treatment of patients with relapsed or refractory multiple myeloma (Press release, Arcellx, JUN 3, 2022, View Source [SID1234615549]). The clinical results are being presented during an oral presentation at the 2022 American Society of Clinical Oncology (ASCO) (Free ASCO Whitepaper) Annual Meeting.

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Evaluable for efficacy and safety analysis were 31 patients, based on follow-up of at least one month, following treatment. These evaluable patients comprised the dose escalation cohorts for the first dose level (100 million CAR+ T cells, n=6), the second dose level (300 million CAR+T cells, n=6), and a dose expansion cohort at the recommended Phase 2 dose (RP2D) of 100 million CAR+T cells (n=19). All patients enrolled in the study have poor prognostic factors with 21 of 31 (68%) patients penta-refractory, 12 of 31 (39%) extramedullary disease (EMD), and all 31 patients having had at least three prior treatments.

The interim CART-ddBCMA clinical results (May 3, 2022 cutoff date) demonstrate deep and durable responses in patients with poor prognostic factors.

Of the 31 evaluable patients with median follow-up of 12.1 months
100% overall response rate (ORR) achieved in all patients per International Myeloma Working Group criteria
22 of 31 (71%) evaluable patients achieved complete response (CR) or a stringent complete response (sCR)
29 of 31 (94%) patients achieved > very good partial response (VGPR)
2 of 31 (6%) patients achieved a partial response (PR)
12 of 31 (39%) with extramedullary disease
13 of 16 patients (81%) dosed more than 12 months ago reached CR/sCR; 8 (50%) with EMD; 9 (56%) remain in ongoing response with a median follow up of 17.7 months
Conversions to sCR have occurred as early as 1 month and also at ≥12 months
CART-ddBCMA dosed at RP2D (100 million CAR+T cells) continues to be well-tolerated
Toxicities including CRS and ICANS have been manageable, and all resolved with standard management at both dose levels
No cases of delayed neurotoxicity events or parkinsonian symptoms
No cases of grade 3 (or greater) CRS and only one case (4%) of grade 3 ICANS event with no additional cases from previously reported.
Matthew J. Frigault, M.D., CART-ddBCMA study investigator and Assistant Director of the Cellular Therapy Service at Mass General Cancer Center and Instructor at Harvard Medical School said, "The demand for clinically meaningful and safe CAR-T therapies outweighs what’s currently available to multiple myeloma patients. It is encouraging to see these data continue to demonstrate deep responses and provide a benefit to patients. I look forward to enrolling patients in the Phase 2 pivotal study."

"We’re excited by these long-term results, particularly given the challenging patient demographics, and believe these promising results reflect the potential for our lead program, CART-ddBCMA, to be a best-in-class treatment for patients with multiple myeloma," said Rami Elghandour, Arcellx’s Chairman and Chief Executive Officer. "We believe there’s a significant unmet need for cell therapies and we’re committed to providing physicians with a safe and effective treatment option for multiple myeloma patients. We’re honored to have our data presented at ASCO (Free ASCO Whitepaper) by Dr. Frigault and look forward to beginning enrollment in our Phase 2 pivotal study by the end of this year as the next step in the path towards regulatory approval."

The presentation can be accessed on the company’s corporate website here.

Oral Presentation Details:
Title: Phase 1 Study of CART-ddBCMA in Relapsed or Refractory Multiple Myeloma
Speaker: Matthew J. Frigault, M.D., Assistant Director of the Cellular Therapy Service at Mass General Cancer Center, and Instructor at Harvard Medical School
Session Type/Title: Oral Abstract Session/Hematologic Malignancies—Plasma Cell Dyscrasia
Session Date: Sunday, June 5, 2022
Session Time: 8:00 a.m. – 11:00 a.m. CDT
Location: McCormick Place Convention Center, Chicago, Illinois
Abstract Number: 8003

Webcast Event:
Arcellx will host a live webcast event with an expert panel of clinicians to discuss the clinical results on Sunday, June 5, 2022, at 7:00 p.m. CDT. The event will be accessible from Arcellx’s website at www.arcellx.com in the Investors section. A replay of the webcast will be archived and available for 30 days following the event.

About Multiple Myeloma
Multiple Myeloma (MM) is a type of hematological cancer in which diseased plasma cells proliferate and accumulate in the bone marrow, crowding out healthy blood cells and causing bone lesions, loss of bone density, and bone fractures. These abnormal plasma cells also produce excessive quantities of an abnormal immunoglobulin fragment, called a myeloma protein (M protein), causing kidney damage and impairing the patient’s immune function. Multiple myeloma is the third most common hematological malignancy in the United States and Europe, representing approximately 10% of all hematological cancer cases and 20% of deaths due to hematological malignancies. The median age of patients at diagnosis is 69 years with one-third of patients diagnosed at an age of at least 75 years. Because MM tends to afflict patients at an advanced stage of life, patients often have multiple co-morbidities and toxicities that can quickly escalate and become life-endangering.

About CART-ddBCMA
CART-ddBCMA is Arcellx’s BCMA-specific CAR-modified T-cell therapy utilizing the company’s novel BCMA-targeting binding domain for the treatment of patients with relapsed or refractory multiple myeloma. CART-ddBCMA is currently in a Phase 1 study. Arcellx’s proprietary binding domains are novel synthetic proteins designed to bind specific therapeutic targets. CART-ddBCMA has been granted Fast Track, Orphan Drug, and Regenerative Medicine Advanced Therapy Designations by the U.S. Food and Drug Administration.