Novel approaches for the interim management of relapsed/refractory acute lymphocytic leukemia: A case-study compendium

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.