SUMMARY: The FDA on March 14, 2024 granted accelerated approval to BREYANZI® (Lisocabtagene maraleucel, Liso-cel), a CD19-directed Chimeric Antigen Receptor (CAR) T-cell therapy, for the treatment of adults with relapsed or refractory Chronic Lymphocytic Leukemia (CLL) or Small Lymphocytic Lymphoma (SLL) who have received at least two prior lines of therapy (including a Brutons Tyrosine Kinase-BTK inhibitor and a B-Cell Lymphoma 2-BCL2 inhibitor).
The American Cancer Society estimates that for 2024, about 20,700 new cases of Chronic Lymphocytic Leukemia (CLL) will be diagnosed in the US and 4440 patients will die of the disease. CLL accounts for about one-quarter of the new cases of leukemia. The average age of patients diagnosed with CLL is around 70 years, and CLL is rarely seen in people under age 40, and is extremely rare in children. Patients with CLL often receive continuous therapy with either Brutons Tyrosine Kinase (BTK) inhibitors such as Ibrutinib (IMBRUVICA®) Acalabrutinib (CALQUENCE®) and Zanubrutinib (BRUKINSA®), time limited therapy with BCL2 inhibitor Venetoclax, given along with anti-CD20 antibody Obinutuzumab, or under certain circumstances, chemoimmunotherapy. Patients have few options and poor outcomes upon progression on these therapies, and there is an unmet need for novel therapies.
Chimeric Antigen Receptor (CAR) T-cell therapy is a type of immunotherapy and consists of T cells collected from the patient’s blood in a leukapheresis procedure, and genetically engineered to produce special receptors on their surface called Chimeric Antigen Receptors (CAR). These reprogrammed cytotoxic T cells with the Chimeric Antigen Receptors on their surface are now able to recognize a specific antigen 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 patients body and the engineered receptor on the cell surface help recognize and kill cancer cells that expresses that specific antigen.
BREYANZI® is a CD19-directed genetically modified autologous T cell immunotherapy, that seeks out cancer cells expressing the antigen CD19, which is found uniquely on B cells and destroy them. BREYANZI® was previously approved by the FDA for treatment of adults with relapsed or refractory Large B-cell lymphoma, who received at least one prior therapy. Patients, following treatment with CAR T-cells, develop B-cell aplasia (absence of CD19 positive cells) due to B-cell destruction and may need immunoglobin replacement. Hence, B-cell aplasia can be a useful therapeutic marker, as continued B-cell aplasia has been seen in all patients who had sustained remission, following CAR T-cell therapy. Cytokine Release Syndrome, an inflammatory process, is the most common and serious side effect of CAR T-cell therapy and is associated with marked elevation of Interleukin-6. Cytokine release is important for T-cell activation and can result in high fevers and myalgias. This is usually self limiting although if severe can be associated with hypotension and respiratory insufficiency. Tocilizumab (ACTEMRA®), an Interleukin-6 receptor blocking antibody, produces a rapid improvement in symptoms. This is however not recommended unless the symptoms are severe and life threatening, as blunting the cytokine response can in turn negate T-cell proliferation. Elevated serum ferritin and C-reactive protein levels are surrogate markers for severe Cytokine Release Syndrome. The CAR T-cells have been shown to also access sanctuary sites such as the CNS and eradicate cancer cells. CD19 antigen is expressed by majority of the B-cell malignancies and therefore most studies using CAR T-cell therapy have focused on the treatment of advanced B-cell malignancies.
TRANSCEND CLL 004 is an open-label, single-arm, multicenter Phase1/2 study, conducted in the United States, to evaluate the efficacy and safety of BREYANZI® in adult patients with relapsed or refractory CLL/SLL. This study included 117 eligible patients who underwent leukapheresis between January 2018 and June 2022, at 27 sites in the United States. Patients received a single intravenous infusion of BREYANZI® at one of two target dose levels: 50×10⁶ (Dose Level 1) or 100×10⁶ (Dose Level 2) Chimeric Antigen Receptor-positive T cells. The median age was 65 years, 68% were men, 44% had bulky lymphadenopathy, and 83% had high-risk cytogenetics. All patients had previously received and failed treatment with a BTK inhibitor and 80% had received prior Venetoclax. Among these patients, 60% had progressed on BTK inhibitors and had Venetoclax failure. Patients had a median of five prior lines of therapy. The Primary endpoint was Complete Response or Remission (including with incomplete marrow recovery), assessed by Independent Review in efficacy-evaluable patients with previous BTK inhibitor progression and Venetoclax failure at Dose Level 2 (100×10⁶). The total efficacy analysis included 89 patients treated at a dose level of 100×10⁶ CAR-positive T cells, with 49 patients evaluable.
In the Primary efficacy analysis set treated at a dose level of 100×10⁶ (N=49), the Complete Response or Remission rate (including with incomplete marrow recovery) was statistically significant at 18% (P=0.0006). The Overall Response Rate was 45%, and the median Duration of Response was 35.3 months. The median Duration of Response in the Complete Responders was Not Reached at the time of data cutoff and Minimal Residual Disease negativity rates were 100% in blood and 92.3% in bone marrow among Complete Responders. The median time to first response was 1.2 months, and for Complete Response or Remission was 3.0 months, respectively.
Among 89 patients in the study treated with BREYANZI®, Cytokine Release Syndrome (CRS) and neurologic events were mostly low-grade. CRS of any grade occurred in 83% of patients, with grade 3 CRS reported in 9% of patients, and with no grade 4 or 5 events reported. Any-grade neurologic events were reported in 46% of patients, with grade 3 neurologic events reported in 20% of patients, and one grade 4 neurologic event reported. No deaths due to either toxicity were reported.
It was concluded that a single infusion of BREYANZI® induced Complete Response or Remission in patients with relapsed or refractory CLL/SLL, including those with previous treatment failure on both BTK inhibitors and Venetoclax. It is the first CAR T-cell therapy approved in this setting and the safety profile was deemed manageable, offering a potential breakthrough in the treatment paradigm for these challenging diseases. Further confirmatory trials will be required to validate these findings and support continued approval of BREYANZI® for this indication.
Lisocabtagene maraleucel in chronic lymphocytic leukaemia and small lymphocytic lymphoma (TRANSCEND CLL 004): a multicentre, open-label, single-arm, phase 1-2 study. Siddiqi T, Maloney DG, Kenderian SS, et al. The Lancet. 2023;402:641-654.
