Inotuzumab ozogamicin in pediatric patients with relapsed/refractory acute lymphoblastic leukemia

Although inotuzumab ozogamicin (InO) is recognized as an effective agent in relapsed acute lymphoblastic leukemia (ALL) in adults, data on safety and efficacy in pediatric patients are scarce. We report the use of InO in 51 children with relapsed/ refractory ALL treated in the compassionate use program. In this heavily pretreated cohort, complete remission was achieved in 67% of patients with overt marrow disease. The majority (71%) of responders were negative for minimal residual disease. Responses were observed irrespective of cytogenetic subtype or number or type of prior treatment regimens. InO was welltolerated; grade 3 hepatic transaminitis or hyperbilirubinemia were noted in 6 (12%) and grade 3/4 infections in 11 (22%) patients. No patient developed sinusoidal obstruction syndrome (SOS) during InO therapy; however, 11 of 21 (52%) patients who underwent hematopoietic stem cell transplantation (HSCT) following InO developed SOS. Downregulation of surface CD22 was detected as a possible escape mechanism in three patients who developed a subsequent relapse after InO. We conclude that InO is a well-tolerated, effective therapy for children with relapsed ALL and prospective studies are warranted. Identification of risk factors for developing post-HSCT SOS and strategies to mitigate this risk are ongoing

Toxicity assessment of molecularly targeted drugs incorporated into multiagent chemotherapy regimens for pediatric Acute Lymphocytic Leukemia (ALL): Review from an International Consensus Conference

One of the challenges of incorporating molecularly targeted drugs into multi-agent chemotherapy (backbone) regimens is defining dose-limiting toxicities (DLTs) of the targeted agent against the background of toxicities of the backbone regimen. An international panel of 22 pediatric acute lymphocytic leukemia (ALL) experts addressed this issue (www.ALLNA.org). Two major questions surrounding DLT assessment were explored: (1) how toxicities can be best defined, assessed, and attributed; and (2) how effective dosing of new agents incorporated into multi-agent ALL clinical trials can be safely established in the face of disease- and therapy-related systemic toxicities. The consensus DLT definition incorporates tolerance of resolving Grade 3 and some resolving Grade 4 toxicities with stringent safety monitoring. This functional DLT definition is being tested in two Children's Oncology Group (COG) ALL clinical trials