Continuous administration of the p38α inhibitor neflamapimod during the subacute phase after transient ischemia-induced stroke in the rat promotes dose-dependent functional recovery accompanied by increase in brain BDNF protein level

Abstract

There is unmet need for effective stroke therapies. Numerous neuroprotection attempts for acute cerebral ischemia have failed and there is growing interest in developing therapies that widen the treatment initiation window and promote functional recovery through increasing synaptic plasticity. The p38 mitogen-activated protein kinase is an already proven target for acute experimental stroke intervention and was hypothesized to also contribute to neuroinflammation-mediated impairment of recovery during the subacute phase. Neflamapimod, an orally bioavailable, brain-penetrant, potent and selective small molecule p38 inhibitor was evaluated as a subacute phase stroke treatment to promote recovery in this research study. Neflamapimod administration at two clinically relevant dose levels was initiated outside of the previously characterized neuroprotection window of less than 24 hours after stroke for p38 inhibitors to rats after transient middle cerebral artery occlusion. Continuous administration of neflamapimod, starting at 48 hours after reperfusion, significantly improved behavioral outcomes assessed by the modified neurological severity score at four- and six-weeks post stroke in a dose-dependent manner. Neflamapimod also demonstrated beneficial effects on additional measures of sensory and motor function and resulted in a dose-related increase in the terminal brain-derived neurotrophic factor protein level in both the injured and uninjured brain hemisphere. Variable interleukin-1{beta} levels were detected in the injured brain hemisphere at study termination in a subset of the animals within every test group, implying ongoing, chronic inflammation, however, no clear neflamapimod effect on interleukin-1{beta} production was observable. The dose-related in vivo efficacy of neflamapimod offers the possibility of both expanding the window for initiation of therapy after stroke and for improving recovery after a completed stroke. Since neflamapimod is already in mid-stage clinical trials for Alzheimers disease and related dementias, the current results make it especially attractive for evaluation in a proof-of- concept clinical trial as therapeutic to promote recovery after ischemic stroke.