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Pharmacological and genetic studies over the past decade have established the follicle-stimulating hormone (FSH) as an actionable target for diseases affecting millions, namely osteoporosis, obesity, and Alzheimer’s disease. Blocking FSH action prevents bone loss, fat gain, and neurodegeneration in mice. We recently developed a first-in-class, humanized, epitope-specific FSH-blocking antibody, MS-Hu6, with a KD of 7.52 nM. Using a Good Laboratory Practice (GLP)-compliant platform, we now report the efficacy of MS-Hu6 in preventing and treating osteoporosis in mice and parameters of acute safety in monkeys. Biodistribution studies using 89Zr-labeled, biotinylated or unconjugated MS-Hu6 in mice and monkeys showed localization to bone and bone marrow. The MS-Hu6 displayed a β phase t½ of 7.5 days (180 hr) in humanized Tg32 mice. We tested 217 variations of excipients using the protein thermal shift assay to generate a final formulation that rendered MS-Hu6 stable in solution upon freeze-thaw and at different temperatures, with minimal aggregation, and without self-, cross-, or hydrophobic interactions or appreciable binding to relevant human antigens. The MS-Hu6 showed the same level of “humanness” as human IgG1 in silico and was non-immunogenic in ELISpot assays for IL-2 and IFN-γ in human peripheral blood mononuclear cell cultures. We conclude that MS-Hu6 is efficacious, durable, and manufacturable, and is therefore poised for future human testing.

Pharmacological and genetic studies over the past decade suggest that FSH is an actionable target for diseases affecting millions, notably osteoporosis, obesity and Alzheimer's disease (AD). Blocking FSH action prevents bone loss (1, 2), fat and energy metabolism (3) and AD–like features in mice (4). We recently developed a first–in–class, humanized, epitope–specific FSH blocking antibody that binds to a 13–amino–acid–long sequence of FSHβ—"MS-Hu6"—with a KD of 7.52 nM (5). We showed that MS-Hu6 bound specifically to FSHβ and its different glycosylated forms, namely FSHβ21/18 and FSHβ24, without binding to LH and TSH. Here, using a GLP–compliant platform, we report the efficacy of MS-Hu6 in preventing obesity, osteoporosis and AD in mice. Notably, MS-Hu6-treated mice showed lower body weight and fat mass, increased lean mass (qNMR) and evidence of beiging in ThermoMice (IVIS imaging) compared with IgG–treated mice. Consistent with this, the thermogenic genes Ucp1 and Cidea were upregulated, whereas Pparg expression was attenuated in fat depots. Treatment of ThermoMice for 8 weeks also increased bone mineral density (BMD), improved microstructure (micro-CT), elevated bone formation (dynamic histomorphometry), and upregulated the osteoblastic genes Alp and Col1a1. The increase in bone mass and improved microstructure were replicated in C.J.R's lab using female mice 24 weeks post–ovariectomy. Preliminary testing using AD mice, namely APP/PS1 mice, showed that MS-Hu6 prevented the impairment in recognition and contextual memory. Biodistribution studies using 89Zr–labelled, biotinylated or unconjugated MS-Hu6 in mice and monkeys showed localization to bone, bone marrow and fat depots. MS-Hu6 displayed a β phase t½ of 13 days (316 hours) in humanized Tg32 mice, and bound endogenous FSH. In monkeys, an acute single injection of MS-Hu6 did not affect vitals, and biochemical parameters remained within the normative range. We tested 215 variations of excipients using the protein thermal shift assay to generate a final formulation that rendered MS-Hu6 stable in solution upon freeze–thaw and at different temperatures, with minimal aggregation, and without self–, cross–, or hydrophobic interactions or appreciable binding to relevant human antigens. MS-Hu6 showed the same level of "humanness" as human IgG1 in silico, and was non–immunogenic in ELISPOT assays for IL-2 and IFNγ in human peripheral blood mononuclear cell cultures. In conclusion, MS-Hu6 is efficacious, durable and manufacturable, and is therefore poised for future human testing as a multipurpose therapeutic for obesity, osteoporosis, and perhaps for AD.References: 1Sun et al., Cell, 2006, PMID: 16630814; Ji et al, PNAS, 2018, PMID: 29440419; 3Liu et al., Nature, 2017, PMID: 28538730; 4Xiong et al., Nature (In press); 5Gera et al., PNAS, 2020, PMID: 33127753 Presentation: Monday, June 13, 2022 12:30 p.m. - 2:30 p.m.

Pharmacological and genetic studies over the past decade have established FSH as an actionable target for diseases affecting millions, notably osteoporosis, obesity and Alzheimer’s disease (AD). Blocking FSH action prevents bone loss, fat gain and AD–like features in mice. We recently developed a first–in–class, humanized, epitope–specific FSH blocking antibody, MS-Hu6, with a KD of 7.52 nM. Using a GLP–compliant platform, we now report the efficacy of MS-Hu6 in preventing obesity and osteoporosis in mice, and parameters of acute safety in monkeys. Biodistribution studies using 89Zr–labelled, biotinylated or unconjugated MS-Hu6 in mice and monkeys showed localization to bone, bone marrow and fat depots. MS-Hu6 displayed a β phase t½ of 13 days (316 hours) in humanized Tg32 mice, and bound endogenous FSH. We tested 215 variations of excipients using the protein thermal shift assay to generate a final formulation that rendered MS-Hu6 stable in solution upon freeze–thaw and at different temperatures, with minimal aggregation, and without self–, cross–, or hydrophobic interactions or appreciable binding to relevant human antigens. MS-Hu6 showed the same level of “humanness” as human IgG1 in silico, and was non–immunogenic in ELISPOT assays for IL-2 and IFNγ in human peripheral blood mononuclear cell cultures. We conclude that MS-Hu6 is efficacious, durable and manufacturable, and is therefore poised for future human testing as a multipurpose therapeutic.

Alzheimer's disease has a higher incidence in older women, with a spike in cognitive decline that tracks with visceral adiposity, dysregulated energy homeostasis and bone loss during the menopausal transition

We report that two widely-used drugs for erectile dysfunction, tadalafil and vardenafil, trigger bone gain in mice through a combination of anabolic and antiresorptive actions on the skeleton. Both drugs were found to enhance osteoblastic bone formation in vivo using a unique gene footprint and to inhibit osteoclast formation. The target enzyme, phosphodiesterase 5A (PDE5A), was found to be expressed in mouse and human bone as well as in specific brain regions, namely the locus coeruleus, raphe pallidus, and paraventricular nucleus of the hypothalamus. Localization of PDE5A in sympathetic neurons was confirmed by coimmunolabeling with dopamine β-hydroxylase, as well as by retrograde bone-brain tracing using a sympathetic nerve-specific pseudorabies virus, PRV152. Both drugs elicited an antianabolic sympathetic imprint in osteoblasts, but with net bone gain. Unlike in humans, in whom vardenafil is more potent than tadalafil, the relative potencies were reversed with respect to their osteoprotective actions in mice. Structural modeling revealed a higher binding energy of tadalafil to mouse PDE5A compared with vardenafil, due to steric clashes of vardenafil with a single methionine residue at position 806 in mouse PDE5A. Collectively, our findings suggest that a balance between peripheral and central actions of PDE5A inhibitors on bone formation together with their antiresorptive actions specify the osteoprotective action of PDE5A blockade.