SUMMARY: Multiple Myeloma is a clonal disorder of plasma cells in the bone marrow and the American Cancer Society estimates that in the United States, 35,730new cases will be diagnosed in 2023 and 12,590 patients are expected to die of the disease. Multiple Myeloma is a disease of the elderly, with a median age at diagnosis of 69 years and characterized by intrinsic clonal heterogeneity. Almost all patients eventually will relapse, and patients with a high-risk cytogenetic profile, extramedullary disease or refractory disease have the worst outcomes. The introduction of Proteasome Inhibitors, Immunomodulatory agents and CD38 targeted therapies has resulted in higher Response Rates, as well as longer Progression Free Survival (PFS) and Overall Survival (OS), with the median survival for patients with myeloma approaching 10 years or more. Nonetheless, multiple myeloma in 2023 remains an incurable disease. Multiple myeloma patients triple refractory to Immunomodulatory drugs (IMiD), Proteasome Inhibitors (PIs), and anti-CD38 monoclonal antibodies have a poor prognosis with a median progression-free survival (PFS) of 3-4 months and a median Overall Survival (OS) of 8-9 months.
With the introduction of new combinations of antimyeloma agents in earlier lines of therapy, patients with Relapsed or Refractory myeloma often have disease that is refractory to multiple drugs. There is an urgent unmet medical need for agents with novel mechanisms of action that are safe and effective, for patients with aggressive and resistant disease.
Chimeric Antigen Receptor (CAR) T-cell therapy has been associated with long-term disease control in some hematologic malignancies and showed promising activity in a Phase 1 study involving patients with Relapsed or Refractory myeloma. B-cell Maturation Antigen (BCMA) is a member of the Tumor Necrosis Factor superfamily of proteins. It is a transmembrane signaling protein primarily expressed by malignant and normal plasma cells and some mature B cells. BCMA is involved in JNK and NF-kB signaling pathways that induce B-cell development and autoimmune responses. BCMA has been implicated in autoimmune disorders, as well as B-lymphocyte malignancies, Leukemia, Lymphomas, and Multiple Myeloma.
Anti-BCMA CAR T-Cell Therapy is a type of immunotherapy and consists of T cells collected from the patient’s blood in a leukapheresis procedure. These T cells are then stimulated by treating with interleukin 2 (IL-2) and anti-CD3 antibodies in vitro, so that they will actively proliferate and expand to large numbers. These T cells are then genetically engineered to produce special receptors on their surface called Chimeric Antigen Receptors (CAR), by transducing with a gene encoding the engineered CAR, via a retroviral vector such as lentiviral vector. These reprogrammed cytotoxic T cells with the Chimeric Antigen Receptors on their surface are now able to recognize a specific antigen such as BCMA on tumor cells. These genetically engineered and reprogrammed CAR T-cells are grown in the lab and are then infused into the patient. These cells in turn proliferate in the patient’s body and the engineered receptor on the cell surface help recognize and kill cancer cells that expresses that specific antigen such as BCMA. The patient undergoes lymphodepletion chemotherapy with Fludarabine and Cytoxan prior to the introduction of the engineered CAR T-cells. By depleting the number of circulating leukocytes, cytokine production is upregulated and reduces competition for resources, which in turn promotes the expansion of the engineered CAR T-cells.
Ciltacabtagene autoleucel (Cilta-cel), a B-cell maturation antigen (BCMA)-directed CAR T-cell therapy, is effective in heavily pretreated patients with Relapsed or Refractory multiple myeloma and was approved by the FDA in February 2022 for the treatment of adult patients with Relapsed or Refractory multiple myeloma after four or more prior lines of therapy, including a Proteasome Inhibitor (PI), an Immunomodulatory agent (IMiD), and an anti-CD38 monoclonal antibody. The researchers in this study investigated the efficacy of cilta-cel in earlier treatment lines among patients with Lenalidomide-refractory disease.
CARTITUDE-4 is an open-label, multicenter, randomized Phase III trial conducted to compare cilta-cel with the physician’s choice of either of two highly effective standard-of-care therapies, in patients with lenalidomide-refractory multiple myeloma after one to three lines of therapy. In this study a total of 419 eligible patients (N=419) were randomly assigned in a 1:1 ratio to receive either one of the standard-of-care physicians choice of PVd-Pomalidomide, Bortezomib, and Dexamethasone, DPd-Daratumumab, Pomalidomide, and Dexamethasone (N=211) or a single infusion of cilta-cel administered after the physician’s choice of bridging therapy with PVd or DPd (N=208). In the standard-of-care group, DPd was administered in 28-day cycles and PVd in 21-day cycles until disease progression. Patients in the cilta-cel group underwent apheresis, followed by at least one bridging therapy cycle, with the number of cycles based on patient clinical status and cilta-cel manufacturing time, and lymphodepletion with Cyclophosphamide 300 mg/m2 IV and Fludarabine 30 mg/m2 IV daily for 3 days. Patients then received a single cilta-cel infusion at a target dose of 0.75X106 CAR-positive T cells/kg of body weight 5-7 days after the initiation of lymphodepletion. The median age was 61 yrs, median time from diagnosis was 3.2 years, about 60% of patients had high risk cytogenetic abnormalities and all patients had received 1-3 previous lines of treatment. In the cilta-cel group, 14.4% had triple-class drug resistance and 24.0% had resistance to anti-CD38 antibody. The Primary outcome was Progression Free Survival and Secondary outcomes sequentially tested included Complete Response (CR) or better, Overall Response Rate (ORR), Minimal Residual Disease (MRD) negativity, and Overall Survival (OS).
Treatment with cilta-cel resulted in a significantly lower risk of disease progression or death than standard-of-care (HR=0.26; P<0.001). The median PFS was not reached in the cilta-cel group and was 11.8 months in the standard-of-care group. Progression-free survival at 12 months was 75.9% in the cilta-cel group and 48.6% in the standard-of-care group. The ORR was 84.6% in the cilta-cel group and 67.3% in the standard-of-care group (P<0.001), the CR rate or better was 73.1% versus 21.8% (P<0.001), and MRD negativity was 60.6% versus 15.6% (P<0.001), respectively. Among the patients who had a response, an estimated 84.7% in the cilta-cel group as compared with 63.0% in the standard-of-care group continued to have a response for at least 12 months.
The most common Grade 3 or 4 adverse events in both groups were hematologic and most high-grade cytopenias in patients who received cilta-cel recovered to Grade 2 or less by day 60. Serious adverse events were reported in 44% of patients in the cilta-cel group and in 39% of patients in the standard-of-care group. Lower rates of cytopenias, Cytokine Release Syndrome, and CAR-T–related neurotoxicity were seen in this study compared to previous cilta-cel studies suggesting that cilta-cel may have a better side-effect profile when used earlier in treatment.
It was concluded that a single cilta-cel infusion resulted in a lower risk of disease progression or death, as well as rapid and deep responses, compared to standard therapies in Lenalidomide-refractory patients with multiple myeloma who had received one to three previous therapies.
Cilta-cel or Standard Care in Lenalidomide-Refractory Multiple Myeloma. San-Miguel J, Dhakal B, Yong K, et al. N Engl J Med 2023;389:335-347.