Chemotherapy-Free First Line Induction and Consolidation Treatment for Acute Lymphocytic Leukemia

SUMMARY: It is estimated that 6150 individuals will be diagnosed with Acute Lymphocytic Leukemia (ALL) in the US and 1520 patients will die of the disease. ALL is more common in children, but can occur at any age and arises from malignant transformation of B- or T-cell progenitor cells. These cells express surface antigens that define their respective lineages. Precursor B-cell ALL cells typically express CD10, CD19, and CD34 on their surface, along with nuclear Terminal deoxynucleotide Transferase (TdT), whereas precursor T-cell ALL cells commonly express CD2, CD3, CD7, CD34, and TdT.

Philadelphia Chromosome (Chromosome 22) is a result of a reciprocal translocation between chromosomes 9 and 22, wherein the ABL gene from chromosome 9 fuses with the BCR gene on chromosome 22. As a result, the auto inhibitory function of the ABL gene is lost and the BCR-ABL fusion gene is activated resulting in cell proliferation and leukemic transformation of hematopoietic stem cells. Approximately 20% of adults and a small percentage of children with ALL are Philadelphia Chromosome (Ph) positive, and in the majority of children and in more than 50% of adults with Ph-positive ALL, the molecular abnormality (fusion protein) is different from that in Ph-positive Chronic Myelogenous Leukemia (p190 versus p210).

Adult patients with Ph-positive ALL are rarely cured with chemotherapy and the prognosis in these patients has markedly improved with the availability of BCR/ABL targeted Tyrosine Kinase Inhibitors (TKIs). Use of these TKIs with or without chemotherapy can result in a Complete Hematologic Remission in 94-100% of patients, irrespective of age. Eligible patients are then usually referred for allogeneic Hematopoietic Stem Cell Transplant (allo HSCT). To increase the chance of cure and decrease the likelihood of relapse, sustained decrease in Minimal Residual Disease is required, with a reduction in the tumor burden to less than 1 tumor cell in 10,000 bone marrow mononuclear cells.BLINATUMOMAB-(BLINCYTO)-(Engages-Two-Different-Targets-Simultaneously)

BiTE® technology (Bispecific T cell Engager antibody) engages the body’s immune system to detect and target malignant cells. These modified antibodies are designed to engage two different targets simultaneously, thereby placing the patient’s T cells within reach of the targeted cancer cell and facilitating apoptosis of the cancer cell. BiTE® antibodies are currently being investigated to treat a wide variety of malignancies. BLINCYTO® (Blinatumomab) is a BiTE® antibody designed to activate the patients T cells with its anti-CD3 group and then bind them to tumor cells with its anti-CD19 group, thus promoting cellular cytotoxicity. CD19 is a protein expressed on the surface of B-cell derived leukemias and lymphomas

The Italian GIMEMA investigators adopted a chemotherapy-free induction strategy and conducted a Phase II single-group trial, in which adults (no upper age limit) with newly diagnosed Ph-positive ALL, received first line therapy with SPRYCEL® (Dasatinib) plus glucocorticoids, followed by two cycles of BLINCYTO® (Blinatumomab). This study enrolled 63 patients with newly diagnosed Ph-positive ALL, and patients received prephase treatment with a glucocorticoid for 7 days before they received SPRYCEL®, and glucocorticoids were continued for an additional 24 days and discontinued on day 31. SPRYCEL® 140 mg orally once daily was administered as induction therapy for 85 days.

Patients who completed the induction phase received consolidation treatment with BLINCYTO® 28 mcg per day, and before each BLINCYTO® cycle, Dexamethasone 20 mg was administered. A minimum of two cycles of BLINCYTO® was mandatory and up to three additional cycles were allowed. Levetiracetam 500 mg twice daily was administered during treatment with BLINCYTO®, to prevent CNS adverse events. SPRYCEL® was continued during treatment with BLINCYTO®, and after BLINCYTO® administration, except in those patients in whom a T315I mutation was detected during the induction phase. Lumbar punctures were performed at diagnosis, at days 14, 22, 43, 57, and 85, and at the end of each BLINCYTO® cycle, for a total of 12 procedures. The choice of postconsolidation treatment, including allogeneic HSCT and subsequent administration of a Tyrosine Kinase Inhibitor, was at the discretion of the investigators. The median patient age was 54 years, 54% of the patients were women, and the median WBC was 13,000 per cubic millimeter. Of the 63 enrolled patients, 65% had the p190 fusion protein, 27% had the p210 fusion protein, and 8% had both. The most frequent molecular aberration was IKZF1 deletion (54%). The Primary endpoint was sustained molecular response in the bone marrow after this treatment.

Complete Hematologic Response was observed in 98% of the patients at the end of SPRYCEL® induction therapy (day 85), and the molecular response rate was 29%, and this percentage increased to 60% after two cycles of BLINCYTO®, with further increase in molecular responses after additional cycles of treatment with BLINCYTO®. At a median follow up of 18 months, Overall Survival was 95% and Disease Free Survival (DFS) was 88%. The probability of DFS among patients who had a molecular response at the end of induction therapy (day 85) was 100%, as compared with 85% among patients with a non-molecular response. There was no significant difference noted in the DFS between patients with p190 and those with p210. Patients who had an IKZF1 deletion along with additional genetic aberrations had lower Disease Free Survivals. Mutations in the ABL1 gene were detected in 6 patients who had increased Minimal Residual Disease during induction therapy, and all these mutations were cleared by BLINCYTO®. A total of 24 patients received an allogeneic HSCT, and the transplantation-related mortality was 4%. The most common adverse events of any grade were pyrexia, cytomegalovirus infection/reactivation and neutropenia.

The authors concluded that a chemotherapy-free induction and consolidation first-line treatment with SPRYCEL® and BLINCYTO®, that was based on a targeted and immunotherapeutic strategy respectively, was associated with high incidences of molecular response and survival, with fewer Grade 3 or higher adverse events, in adults with Philadelphia chromosome-positive ALL.

Dasatinib-Blinatumomab for Ph-Positive Acute Lymphoblastic Leukemia in Adults. Foà R, Bassan R, Vitale A, et al. for the GIMEMA Investigators. N Engl J Med 2020; 383:1613-1623

ASPARLAS® (Calaspargase pegol-mknl)

The FDA on December 20, 2018 approved ASPARLAS®, an asparagine specific enzyme, as a component of a multi-agent chemotherapeutic regimen for Acute Lymphoblastic Leukemia (ALL) in pediatric and young adult patients age 1 month to 21 years. This new product provides for a longer interval between doses compared to other available pegaspargase products. ASPARLAS® is a product of Servier Pharmaceuticals LLC.

BLINCYTO® (Blinatumomab)

The FDA on March 29, 2018 granted accelerated approval to BLINCYTO® for the treatment of adult and pediatric patients with B-cell precursor Acute Lymphoblastic Leukemia (ALL) in first or second complete remission with Minimal Residual Disease (MRD) greater than or equal to 0.1%. BLINCYTO® is a product of Amgen Inc.

KYMRIAH® (Tisagenlecleucel)

The FDA on August 30, 2017 granted regular approval to KYMRIAH®, for the treatment of patients up to age 25 years with B-cell precursor Acute Lymphoblastic Leukemia (ALL), that is refractory or in second or later relapse. KYMRIAH® is a product of Novartis Pharmaceuticals Corp.

First CAR T-Cell Immunotherapy Approved by the FDA for Acute Lymphoblastic Leukemia

The FDA on August 30, 2017, granted regular approval to KYMRIAH® (Tisagenlecleucel) for the treatment of patients up to age 25 years with B-cell precursor Acute Lymphoblastic Leukemia (ALL), that is refractory or in second or later relapse. KYMRIAH® is the first Chimeric Antigen Receptor (CAR) T-cell immunotherapy approved by the FDA. A single infusion of KYMRIAH® was highly efficacious, in patients with relapsed and refractory ALL, and was associated with a high and durable Remission Rate. This technology may be applied to other malignancies, as new antigen targets are identified.

First CAR T-Cell Immunotherapy Approved by the FDA for Acute Lymphoblastic Leukemia

SUMMARY: The FDA on August 30, 2017, granted regular approval to KYMRIAH® (Tisagenlecleucel) for the treatment of patients up to age 25 years with B-cell precursor Acute Lymphoblastic Leukemia (ALL), that is refractory or in second or later relapse. KYMRIAH® is the first Chimeric Antigen Receptor (CAR) T-cell immunotherapy approved by the FDA.

What is (CAR) T-cell immunotherapy? 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 patient’s body and the engineered receptor on the cell surface help recognize and kill cancer cells that expresses that specific antigen. KYMRIAH® (genetically engineered T-cells) seeks out cancer cells expressing the antigen CD19, which is found uniquely on B cells and destroy them. 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 central nervous system 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 such as Chronic Lymphocytic Leukemia (CLL), Acute Lymphoblastic Leukemia (ALL) and Non Hodgkin lymphoma (NHL), such as Diffuse Large B-Cell Lymphoma (DLBCL). Previously published studies have shown significant responses with CAR T-cell therapy in patients with relapsed and refractory B-cell ALL. But the durability of remission has remained unclear.

This FDA approval was based on ELIANA, an ongoing single-arm, open-label, multicenter, global, phase II study, that has enrolled 88 pediatric/young adult patients with CD19-positive Relapsed/Refractory B-cell ALL and with 5% or more bone marrow lymphoblasts by morphology. The median age was 12 years, 59% of patients had prior allogeneic Stem Cell Transplant and patients had received a median of 3 lines of therapy previously. Following completion of lymphodepleting chemotherapy which in most patients consisted of Fludarabine/Cyclophosphamide, patients were infused with a single dose of KYMRIAH® within 2 to 14 days following the completion of lymphodepleting chemotherapy. The primary endpoint was Overall Remission Rate – Complete Remission [CR] + CR with incomplete blood count recovery [CRi], within 3 months. Secondary endpoints included Duration of Remission (DOR), Overall Survival, Safety, and cellular kinetics.

The authors reported an updated interim analysis with a median study follow up of 6.4 months. Of the 63 patients who were evaluable for efficacy, the Overall Remission Rate was 83%, with 63% of patients achieving a Complete Remission (CR) and 19% achieving a Complete Remission with incomplete hematological recovery (CRi) within 3 months of KYMRIAH® infusion. All patients with a confirmed CR or CRi were Minimal Residual Disease (MRD) negative by flow cytometry. The relapse-free probability at 6 months after remission onset was 75% and the median Duration of Remission has not been reached. The probability of survival at 6 months was 89% and at 12 months was 79%. Thirteen percent (13%) of responders went on to have allogeneic Stem Cell Transplant within 6 months, while in remission.

The most common adverse reactions were Cytokine Release Syndrome (CRS), hypogammaglobulinemia, nausea, diarrhea, vomiting, fever, infections, headache, encephalopathy, hypotension, bleeding episodes, tachycardia, hypoxia and fatigue. Grade 3 or 4 adverse events were noted in 84% of patients. Patients with Severe Cytokine Release Syndrome were effectively treated with the Interleukin-6 receptor blocking antibody Tocilizumab (ACTEMRA®). The expansion of the genetically engineered T-cells in vivo correlated with CRS severity, and persistence of these reprogrammed T cells along with B-cell aplasia in peripheral blood was observed for 1 year or more in some responders.

The authors concluded that the ELIANA trial is the first multicenter trial of a CAR T-cell therapy and a single infusion of KYMRIAH® was highly efficacious, in patients with relapsed and refractory ALL, and was associated with a high and durable remission rate. This technology may be applied to other malignancies, as new antigen targets are identified. Buechner J, Grupp SA, Maude SL, et al. Global registration trial of efficacy and safety of CTL019 in pediatric and young adult patients with relapsed/refractory (r/r) acute lymphoblastic leukemia (ALL): update to the interim analysis. Presented at: 2017 EHA Congress; June 22-25, 2017; Madrid, Spain. Abstract S476.