Marcelo C. Pasquini

Chimeric antigen receptor (CAR) T cell therapy is rapidly emerging as one of the most promising therapies for hematologic malignancies. Two CAR T products were recently approved in the United States and Europe for the treatment ofpatients up to age 25years with relapsed or refractory B cell acute lymphoblastic leukemia and/or adults with large B cell lymphoma. Many more CAR T products, as well as other immunotherapies, including various immune cell- and bi-specific antibody-based approaches that function by activation of immune effector cells, are in clinical development for both hematologic and solid tumor malignancies. These therapies are associated with unique toxicities of cytokine release syndrome (CRS) and neurologic toxicity. The assessment and grading of these toxicities vary considerably across clinical trials and across institutions, making it difficult to compare the safety of different products and hindering the ability to develop optimal strategies for management of these toxicities. Moreover, some aspects of these grading systems can be challenging to implement across centers. Therefore, in an effort to harmonize the definitions and grading systems for CRS and neurotoxicity, experts from all aspects of the field met on June 20 and 21, 2018, at a meeting supported by the American Society for Transplantation and Cellular Therapy (ASTCT; formerly American Society for Blood and Marrow Transplantation, ASBMT) in Arlington, VA. Here we report the consensus recommendations of that group and propose new definitions and grading for CRS and neurotoxicity that are objective, easy to apply, and ultimately more accurately categorize the severity of these toxicities. The goal is to provide a uniform consensus grading system for CRS and neurotoxicity associated with immune effector cell therapies, for use across clinical trials and in the postapproval clinical setting.

Defining conditioning regimen intensity has become a critical issue for the hemopoietic stem cell transplant (HSCT) community. In the present report we propose to define conditioning regimens in 3 categories: (1) myeloablative (MA) conditioning, (2) reduced-intensity conditioning (RIC), and (3) nonmyeloablative (NMA) conditioning. Assignment to these categories is based on the duration of cytopenia and on the requirement for stem cell (SC) support: MA regimens cause irreversible cytopenia and SC support is mandatory. NMA regimens cause minimal cytopenia, and can be given also without SC support. RIC regimens do not fit criteria for MA or NMA regimens: they cause cytopenia of variable duration, and should be given with stem cell support, although cytopenia may not be irreversible. This report also assigns commonly used regimens to one of these categories, based upon the agents, dose, or combinations. Standardized classification of conditioning regimen intensities will allow comparison across studies and interpretation of study results.

BACKGROUND: Data are lacking on whether lenalidomide maintenance therapy prolongs the time to disease progression after autologous hematopoietic stem-cell transplantation in patients with multiple myeloma. METHODS: Between April 2005 and July 2009, we randomly assigned 460 patients who were younger than 71 years of age and had stable disease or a marginal, partial, or complete response 100 days after undergoing stem-cell transplantation to lenalidomide or placebo, which was administered until disease progression. The starting dose of lenalidomide was 10 mg per day (range, 5 to 15). RESULTS: The study-drug assignments were unblinded in 2009, when a planned interim analysis showed a significantly longer time to disease progression in the lenalidomide group. At unblinding, 20% of patients who received lenalidomide and 44% of patients who received placebo had progressive disease or had died (P<0.001); of the remaining 128 patients who received placebo and who did not have progressive disease, 86 crossed over to lenalidomide. At a median follow-up of 34 months, 86 of 231 patients who received lenalidomide (37%) and 132 of 229 patients who received placebo (58%) had disease progression or had died. The median time to progression was 46 months in the lenalidomide group and 27 months in the placebo group (P<0.001). A total of 35 patients who received lenalidomide (15%) and 53 patients who received placebo (23%) died (P=0.03). More grade 3 or 4 hematologic adverse events and grade 3 nonhematologic adverse events occurred in patients who received lenalidomide (P<0.001 for both comparisons). Second primary cancers occurred in 18 patients who received lenalidomide (8%) and 6 patients who received placebo (3%). CONCLUSIONS: Lenalidomide maintenance therapy, initiated at day 100 after hematopoietic stem-cell transplantation, was associated with more toxicity and second cancers but a significantly longer time to disease progression and significantly improved overall survival among patients with myeloma. (Funded by the National Cancer Institute; ClinicalTrials.gov number, NCT00114101.).

During the 2006 BMT Tandem Meetings, a workshop was convened by the Center for International Blood and Marrow Transplant Research (CIBMTR) to discuss conditioning regimen intensity and define boundaries of reduced-intensity conditioning (RIC) before hematopoietic cell transplantation (HCT). The goal of the workshop was to determine the acceptance of available RIC definitions in the transplant community. Participants were surveyed regarding their opinions on specific statements on conditioning regimen intensity. Questions covered the "Champlin criteria," as well as operational definitions used in registry studies, exemplified in clinical vignettes. A total of 56 participants, including transplantation physicians, transplant center directors, and transplantation nurses, with a median of 12 years of experience in HCT, answered the survey. Of these, 67% agreed that a RIC regimen should cause reversible myelosuppression when administered without stem cell support, result in low nonhematologic toxicity, and, after transplantation, result in mixed donor-recipient chimerism at the time of first assessment in most patients. Likewise, the majority (71%) agreed or strongly agreed that regimens including < 500 cGy of total body irradiation as a single fraction or 800 cGy in fractionated doses, busulfan dose < 9 mg/kg, melphalan dose <140 mg/m(2), or thiotepa dose < 10 mg/kg should be considered RIC regimens. However, only 32% agreed or strongly agreed that the combination of carmustine, etoposide, cytarabine, and melphalan (BEAM) should be considered a RIC regimen. These results demonstrate that although HCT professionals have not reached a consensus on what constitutes a RIC regimen, most accept currently used criteria and operational definitions. These results support the continued use of current criteria for RIC regimens until a consensus statement can be developed.