What is the impact, present and future, of novel targeted agents in acute lymphoblastic leukemia?

The Combination of the PARP Inhibitor Rucaparib and 5FU Is an Effective Strategy for Treating Acute Leukemias

The existing treatments to cure acute leukemias seem to be nonspecific and suboptimal for most patients, drawing attention to the need of new therapeutic strategies. In the last decade the anticancer potential of poly ADP-ribose polymerase (PARP) inhibitors became apparent and now several PARP inhibitors are being developed to treat various malignancies. So far, the usage of PARP inhibitors has been mainly focused on the treatment of solid tumors and not too much about their efficacy on leukemias is known. In this study we test, for the first time on leukemic cells, a combined therapy that associates the conventional chemotherapeutic agent fluorouracil (5FU), used as a source of DNA damage, and a PARP inhibitor, rucaparib. We demonstrate the efficacy and the specificity of this combined therapy in killing both acute myeloid leukemia and acute lymphoid leukemia cells in vitro and in vivo. We clearly show that the inhibition of DNA repair induced by rucaparib is synthetic lethal with the DNA damage caused by 5FU in leukemic cells. Therefore, we propose a new therapeutic strategy able to enhance the cytotoxic effect of DNA-damaging agents in leukemia cells via inhibiting the repair of damaged DNA.

Acute lymphoblastic leukemia in adolescents and young adults

The cure rate of acute lymphoblastic leukemia (ALL) in children is 80%, compared to less than half in adults. A major proportion of this cure rate drop occurs in adolescents and young adults (AYAs). The age range defining this population varies between studies, biological characteristics are different from both younger children and older adults, and AYAs are treated either by pediatric or adult oncologists, who often apply different treatment approaches to the same ALL patient population. The outcome of AYAs aged 15-21 years treated by more contemporary pediatric protocols is similar to that of younger children but is inferior when using adult regimens. This motivated studying AYA patients, including those above the age of 21 years, with pediatric or 'pediatrics-inspired' regimens that intensified nonmyelosuppressive drugs such as vincristine, steroids and asparaginase, with very promising preliminary results. Discovering new mutations in AYA ALL will help stratify patients into risk subgroups and identify targets for novel agents. This, together with fine-tuning pediatric chemotherapy principles will hopefully finally decrease the cure rate gap between children and AYAs - and even older adults.