Search

Before the development of tyrosine kinase inhibitors (TKIs), the outcome of patients with a diagnosis of Philadelphia chromosome (Ph)-positive acute lymphoblastic leukemia was dismal. Combinations of TKIs and chemotherapy improved survival rates, but allogeneic stem cell transplant was still relied on to avoid relapse in most cases. More recently, the chemotherapy-free combination of blinatumomab plus newer-generation TKIs has shown favorable results and may eliminate the need for allogeneic stem cell transplant. This review discusses the evolution of the treatment of Ph-positive acute lymphoblastic leukemia with chemotherapy-free regimens in the current era.

Acute lymphoblastic leukemia, commonly known to affect the younger population, is a disease that is affecting the elderly in an increasing amount as the human life span continues to lengthen. Traditional cytotoxic agents are intolerable to elderly individuals owing to comorbidities, weakened immune systems, and organ dysfunction. Alternative agents and regimens are needed to allow for elderly patient to tolerate full cycles of therapy while providing complete and durable remissions. With the advent of targeted agents, such as monoclonal antibodies and bispecific T-cell engagers, a number of options have proven themselves to be effective in the elderly and optimal for tolerability. Here, we review and discuss the literature addressing regimens that use new agents, such as blinatumomab, inotuzumab ozogamicin, and venetoclax, and those that use modified dosing strategies of traditional chemotherapy.

Tyrosine kinase inhibitors (TKIs) represent a major breakthrough in the treatment of chronic myeloid leukemia (CML). Thanks to these agents, CML has been transformed from a disease with limited treatment options and a dismal prognosis into a more indolent disease with survival comparable to that of the general population. The need for ongoing TKI therapy remains controversial for several reasons, including cost and toxicity. Studies in CML patients with a sustained deep molecular response have demonstrated that stopping TKI therapy is feasible and safe. Given the heterogeneity of results reported in clinical trials, practice guidelines for optimal patient selection and proper monitoring after discontinuation of TKIs are proposed outside of clinical trials. Current data available show that 40% to 60% of patients who stop therapy relapse; molecular relapses typically occur within 6 months, but nearly all relapsing patients regain response upon reinitiation of the TKI. Several factors that predict for relapse have been investigated. Duration of prior TKI therapy, achievement of deep molecular response, depth of molecular response, prior interferon treatment, and Sokal risk score have been shown to be potential predictors for relapse. Leukemia stem cells that are resistant to TKIs, and that persist despite undetectable BCR/ABL1 transcript levels, likely are responsible for disease relapse after discontinuation. Efforts geared toward better identification of low levels of BCR/ABL1 transcript using new techniques such as digital polymerase chain reaction, along with eradicating CML clones using combination therapies with agents such as pegylated interferon or venetoclax with TKIs, will hopefully lead to a functional cure of this disease.

Patients with relapsed or refractory acute lymphoblastic leukemia (R/R ALL) have dismal outcomes, with survival of less than 6 months, and treatment options in the salvage setting have been limited to conventional cytotoxic chemotherapy with minimal activity. Advances in the development of novel targeted therapies have significantly improved outcomes in R/R ALL. Blinatumomab, inotuzumab ozogamicin, and chimeric antigen receptor (CAR) T-cell therapy constitute new treatment modalities that are challenging the historical regimens and paving a new path for treating patients with R/R ALL.

The heterogeneous hematologic malignancy acute lymphocytic leukemia (ALL) represents one of the more complicated cancers in adults. Despite the large number of agents available to treat this disease, there remains no standard of care for either the frontline or relapsed/refractory settings. Although the rate of response to initial induction therapy is high, at least half of patients experience relapsed or refractory disease. Selection of salvage therapy may rely on investigational strategies in clinical trials. The goal of frontline or salvage therapy is to reduce the tumor burden so that patients can proceed to allogeneic stem cell transplant, the only treatment considered potentially curative for ALL. However, the different combination chemotherapy regimens are associated with unpredictable responses and can result in myelosuppression and other toxicities. The need for improved treatment alternatives, especially in the salvage setting, has been recently addressed with the introduction of several new therapies. Chimeric antigen receptor (CAR) T-cell therapy is a form of immunotherapy. T cells harvested from the patient are genetically engineered to express a receptor that targets a tumor-specific antigen on the tumor cell surface. Patients awaiting CAR T-cell therapy, like those awaiting stem cell transplant, often require a “bridge” treatment during the interim. A liposomal formulation of vincristine has been associated with durable responses in relapsed disease, but with less myelosuppression and neurotoxicity than standard vincristine. Other novel agents include blinatumomab and inotuzumab ozogamicin.

Acute lymphoblastic leukemia (ALL) is a heterogeneous hematologic malignancy characterized by highly proliferative immature lymphoid cells in the bone marrow and peripheral blood. In adults, ALL accounts for approximately 20% of all adult leukemias. ALL carries a poor prognosis in adults. The 5-year overall survival is 24% in patients ages 40 to 59 years and 18% in patients ages 60 to 69 years. ALL can be grouped into different categories according to its cell lineage (B cell or T cell), the presence or absence of the Philadelphia chromosome, and various cytogenetic and molecular classifications. A main goal of treatment is to allow the patient to achieve a complete remission and to consolidate this remission with either a maintenance regimen or an allogeneic stem cell transplant. Although the overall rate of complete remission following frontline therapy for newly diagnosed ALL is high, the majority of patients experience a disease relapse. In general, the duration of initial complete remission impacts the patient’s prognosis and response to further therapies. Subsequent treatments must balance the goal of achieving a remission with the need for the patient to maintain or improve quality of life. Recently approved agents, such as blinatumomab and vincristine sulfate liposome injection, offer the promise of a second remission that can serve as a bridge to allogeneic stem cell transplant while still maintaining quality of life. A novel approach using adoptive cellular immunotherapy with chimeric antigen receptor (CAR) T cells is associated with extremely robust responses.

Acute lymphoblastic leukemia (ALL) is a heterogeneous hematologic malignancy characterized by proliferation of immature lymphoid cells throughout the bone marrow and peripheral blood. Most cases are diagnosed before the age of 20 years. Adults have a worse prognosis than children. Approximately half of adult ALL patients relapse after their initial treatment. There is no standard treatment for ALL; strategies vary according to the patient’s age, comorbidities, and Philadelphia chromosome status. Regimens used in pediatric patients are being adapted for use in adults. Frontline management can include hyperfractionated cyclophosphamide, vincristine, doxorubicin, and dexamethasone alternating with cycles of high-dose methotrexate and cytarabine (hyper-CVAD) and the Berlin-Frankfurt-Münster regimen. Relapsed/refractory patients have several options, including a regimen consisting of fludarabine, high-dose cytarabine, and granulocyte colony–stimulating factor (FLAG); tyrosine kinase inhibitors; and chemotherapy. The US Food and Drug Administration recently approved 3 therapies for these patients: clofarabine, nelarabine, and vincristine sulfate liposome injection, a modified formulation of vincristine that allows the drug to be administered at a higher dosage. Several novel strategies are currently under investigation, including the monoclonal antibody blinatumomab, a bispecific T-cell engager that targets the B-cell–specific antigen CD19 and activates T cells to exert cytotoxic activity against the target B cell. This clinical roundtable monograph features case studies that illustrate important points in the management of adult patients with relapsed/refractory ALL.

Approximately 5,000 cases of chronic myelogenous leukemia (CML) are diagnosed each year in the United States. The introduction of tyrosine kinase inhibitors (TKIs) has dramatically improved survival time for many CML patients. Current first-line treatment options include imatinib and the second-generation agents nilotinib and dasatinib. Second- and third-line agents include nilotinib, dasatinib, bosutinib, and the new agent ponatinib. Despite the effectiveness of TKIs, some patients develop resistance or intolerance to these agents. A number of mutations of the BCR-ABL gene have been identified and are associated with TKI resistance. Patients may benefit from switching to a second-line TKI, undergoing hematopoietic stem cell transplant, or receiving newly emerging agents. Although early response is associated with improved patient outcome, clinicians lack tests that can determine which patients will benefit from which therapies. To ensure adequate response, patients should be monitored by both polymerase chain reaction and cytogenetic analysis of the bone marrow. This roundtable monograph reviews key unmet needs in patients with CML related to disease management and treatment options.