Development of Pirenzepine for HIV-SN - PROJECT SUMMARY
Over 36.7 million people worldwide, including 1.2 million people in the USA are HIV positive. HIV-associated
sensory neuropathy (HIV-SN) is the most frequent neurological manifestation of HIV and is characterized as a
distal symmetrical, predominantly sensory, polyneuropathy. HIV-SN may represent 2 clinically indistinguishable
neuropathies with distinct pathogenesis: a distal axonal degeneration caused by interaction of sensory neurons
with HIV-associated proteins such as gp120 and Tat and also an anti-retroviral therapy (ART)-induced toxic
neuropathy, ART may also potentiate the HIV-SN induced by HIV proteins. Recent studies have implicated
mitochondrial dysfunction in the pathogenesis of HIV-SN and disruption of neuronal mitochondrial biogenesis
and quality control (biogenesis-mitophagy axis) occurs in HIV-SN patients. There is no current treatment that
targets a pathological process underlying HIV-SN, but the emerging appreciation of the role of mitochondrial
dysfunction in the underlying pathogenesis provides a potential therapeutic approach. The academic founders
of WinSanTor recently reported that neurite outgrowth from peripheral sensory neurons is under a cholinergic
constraint mechanism mediated by type 1 muscarinic receptors (M1R). Stimulation of the M1R restrains
mitochondrial function, thereby limiting neuronal energy supply and neurite growth. Conversely, inhibition of M1R
activates AMP-activated protein kinase (AMPK) with subsequent enhancement of mitochondrial bioenergetic
function and neurite regeneration. M1R inhibition also prevents and reverses indices of distal degenerative
neuropathy in animal models of diabetic and chemotherapy-induced neuropathy. These promising findings
suggest that the therapeutic efficacy of M1R antagonists has the potential to extend across diverse peripheral
neuropathies in which mitochondrial function is compromised. We have recently found that mouse models that
overexpress HIV-associated proteins exhibit mitochondrial dysfunction and develop symptoms of neuropathy.
Further,
reduced neurite outgrowth from sensory neurons exposed to the HIV protein gp120 in vitro was
prevented by treatment with the M1R antagonist pirenzepine, while loss of corneal nerves induced by delivery
of gp120 to the eye of normal mice was both prevented and reversed by concurrent topical application of
a M1R
antagonist. Based on these results, the goal of this Phase I STTR project is to 1) evaluate efficacy of pirenzepine
against neuropathy in mice expressing HIV-Tat protein; 2) evaluate efficacy of pirenzepine against neuropathy
in mice expressing HIV-gp120 protein with concurrent ART therapy. Successful completion of this Phase I
project will support further pre-clinical development of pirenzepine as a novel therapeutic for treatment of HIV-
SN. In Phase II, we will further define the safety/toxicology profiles of pirenzepine to support filing of an IND
application with the FDA.
