Age-Dependent Cellular and Behavioral Deficits Induced by Molecularly Targeted Drugs Are Reversible

Abstract

Newly developed targeted anticancer drugs inhibit signaling pathways commonly altered in adult and pediatric cancers. However, as these pathways are also essential for normal brain development, concerns have emerged of neurologic sequelae resulting specifically from their application in pediatric cancers. The neural substrates and age dependency of these druginduced effects in vivo are unknown, and their long-term behavioral consequences have not been characterized. This study defines the age-dependent cellular and behavioral effects of these drugs on normally developing brains and determines their reversibility with post-drug intervention. Mice at different postnatal ages received short courses of molecularly targeted drugs in regimens analagous to clinical treatment. Analysis of rapidly developing brain structures important for sensorimotor and cognitive function showed that, while adult administration was without effect, earlier neonatal administration of targeted therapies attenuated white matter oligodendroglia and hippocampal neuronal development more profoundly than later administration, leading to long-lasting behavioral deficits. This functional impairment was reversed by rehabilitation with physical and cognitive enrichment. Our findings demonstrate age-dependent, reversible effects of these drugs on brain development, which are important considerations as treatment options expand for pediatric cancers.Significance: Targeted therapeutics elicit age-dependent longterm consequences on the developing brain that can be ameliorated with environmental enrichment. Cancer Res; 1-15. Ó2018 AACR.

Conventional laboratory housing increases morbidity and mortality in research rodents: results of a meta-analysis

“…Conversely (but equally concerning), some null or adverse results in CH animals instead indicate promising therapies if subjects are better housed. For example, the harmful neurological side-effects of some novel anti-cancer agents on CH mice are diminished or even abolished in mice in less poor conditions [ 117 ]; in stroke research, epidermal growth factor does not improve recovery in CH rats, but does for rats in improved housing [ 118 ]; and flu vaccines which elicit only weak antigen-specific immunity in CH mice, have much greater benefits in better-housed conspecifics [ 119 ]. ‘Would conducting experiments under more than one set of conditions improve translation of knowledge to the clinic?’ ask Hylander & Repasky (2016) in Trends in Cancer [ 83 ] .…”