Targeting Pathogenic Lafora Bodies in Lafora Disease Using an Antibody-Enzyme Fusion.

Lafora disease (LD) is a fatal childhood epilepsy caused by recessive mutations in either the EPM2A or EPM2B gene. A hallmark of LD is the intracellular accumulation of insoluble polysaccharide deposits known as Lafora bodies (LBs) in the brain and other tissues. In LD mouse models, genetic reduction of glycogen synthesis eliminates LB formation and rescues the neurological phenotype. Therefore, LBs have become a therapeutic target for ameliorating LD. Herein, we demonstrate that human pancreatic α-amylase degrades LBs. We fused this amylase to a cell-penetrating antibody fragment, and this antibody-enzyme fusion (VAL-0417) degrades LBs in vitro and dramatically reduces LB loads in vivo in Epm2a-/- mice. Using metabolomics and multivariate analysis, we demonstrate that VAL-0417 treatment of Epm2a-/- mice reverses the metabolic phenotype to a wild-type profile. VAL-0417 is a promising drug for the treatment of LD and a putative precision therapy platform for intractable epilepsy.

Radiolabeled antibodies directed at CD45 for conditioning prior to allogeneic transplantation in acute myeloid leukemia and myelodysplastic syndrome.

While allogeneic hematopoietic cell transplantation (HCT) may offer the best chance of cure for patients suffering from aggressive hematological malignancies such as acute myeloid leukemia, acute lymphoblastic leukemia, and myelodysplastic syndrome, successful outcomes for the subgroup of patients with high-risk disease remain disappointing and lag behind those of lower-risk patients. Because relatively high rates of relapse are an important contributor to these poor outcomes, efforts have explored approaches to increase the cytotoxic effects of treatment. Relapse rates have been shown to improve with the addition of increased doses of total body irradiation (TBI) and/or the introduction of additional chemotherapy to a HCT conditioning regimen. However, the increase in TBI dose and/or additional chemotherapy has also been associated with a significant increase in life-threatening toxicities, resulting in no change in overall survival. Radioimmunotherapy (RIT) has been employed as an adjunct to HCT where targeted delivery of radiation may allow for further escalation of therapy to reduce relapse with minimal toxicity. In this review we describe these efforts, including the benefits of escalating the dose of radiation to sites of hematologic disease prior to HCT, the various cellular targets for antibody-mediated delivery of radiation, as well as the rationale for incorporation of various radionuclides such as alpha emitters and beta emitters into the preparative regimen prior to HCT. Lastly, newer novel approaches such as pretargeted RIT (PRIT) are described as a method to further increase delivery of targeted radiation to hematological tissues while sparing noninvolved organs.