Cytokine Release Syndrome in Patients with Relapsed/Refractory Multiple Myeloma Treated with Ciltacabtagene Autoleucel in the Phase 1b/2 CARTITUDE-1 Study

Background: The phase 1b/2 CARTITUDE-1 study (NCT03548207) is evaluating ciltacabtagene autoleucel (cilta-cel; JNJ-68284528; LCAR-B38M CAR-T cells), a chimeric antigen receptor T (CAR-T) cell therapy with 2 B-cell maturation antigen–targeting single-domain antibodies, in patients with relapsed/refractory (R/R) multiple myeloma (MM). Cytokine release syndrome (CRS), a known side effect of CAR-T therapy, can be mild to life-threatening and requires careful monitoring and management. Here, we analyzed CRS and cytokine profiles in CARTITUDE-1.

Methods: Eligible patients (aged ≥18 years) had a diagnosis of MM per International Myeloma Working Group criteria, measurable disease, Eastern Cooperative Oncology Group performance status ≤1, received ≥3 prior regimens or were double-refractory to a proteasome inhibitor and immunomodulatory drug, and received an anti-CD38 antibody. Bridging therapy was permitted after apheresis. At 5–7 days prior to cilta-cel infusion, lymphodepletion was performed with cyclophosphamide 300 mg/m² and fludarabine 30 mg/m² daily for 3 days. Cilta-cel was administered as a single infusion at a target dose of 0.75×10⁶ (range: 0.5–1.0×10⁶) CAR+ viable T cells/kg. CRS was graded using Lee et al (Blood 2014) in the phase 1b portion and American Society for Transplantation and Cellular Therapy (ASTCT) in the phase 2 portion. In this combined analysis, Lee et al criteria were mapped to ASTCT criteria for patients in the phase 1b portion. Serum samples for cytokine profiling were collected prior to lymphodepletion, prior to cilta-cel infusion and 2 hours post-infusion on Day 1, at regular time points until Day 100, and if CRS was suspected or reported.

Results: A total of 97 patients with R/R MM were treated with cilta-cel; median follow-up for this analysis was 8.8 months (range: 1.5–20.4). CRS was reported in 92 (94.8%) patients. A total of 48 (49.5%) patients had grade 1 CRS, 38 (39.2%) had grade 2, 4 (4.1%) had grade 3, and 1 had grade 5 (1.0%); maximum toxicity grade according to the ASTCT consensus grading system could not be derived for 1 patient with CRS in the phase 1b portion. Median time to CRS onset from cilta-cel infusion was 7.0 days (range: 1–12). Median duration of CRS was 4.0 days (range: 1–27, excluding n=1 with 97 days). Supportive measures to treat CRS or CRS symptoms were administered to 87 (89.7%) patients, most commonly tocilizumab (69.1%), acetaminophen (68.0%), corticosteroids (20.6%), and anakinra (18.6%). CRS resolved in 91 (98.9%) patients; the patient with grade 5 CRS/hemophagocytic lymphohistiocytosis died on Day 99 subsequent to sequelae of grade 4 CRS. Across all patients, levels of interleukin (IL)-6, IL-10, and interferon-γ peaked at Days 7–14 post-cilta-cel infusion.

Conclusions: CRS after cilta-cel treatment was low grade and manageable in most patients with R/R MM. The low rate of grade ≥3 CRS, median time to CRS onset of 7.0 days, and median duration of 4.0 days suggests outpatient dosing of cilta-cel may be feasible; this approach is being explored in the phase 2 CARTITUDE-2 study (NCT04133636).