Targeting the Wnt signaling pathway for the development of novel therapies for osteoporosis

An in situ depot for the sustained release of a TLR7/8 agonist in combination with a TGFβ inhibitor promotes anti-tumor immune responses

Cancer curing immune responses against heterogeneous solid cancers require that a coordinated immune activation is initiated in the antigen avid but immunosuppressive tumor microenvironment (TME). The plastic TME, and the poor systemic tolerability of immune activating drugs are, however, fundamental barriers to generating curative anticancer immune responses. Here, we introduce the CarboCell technology to overcome these barriers by forming an intratumoral sustained drug release depot that provides high payloads of immune stimulatory drugs selectively within the TME. The CarboCell thereby induces a hot spot for immune cell training and polarization and further drives and maintains the tumor-draining lymph nodes in an anticancer and immune activated state. Mechanistically, this transforms cancerous tissues, consequently generating systemic anticancer immunoreactivity. CarboCell can be injected through standard thin-needle technologies and has inherent imaging contrast which secure accurate intratumoral positioning. In particular, here we report the therapeutic performance for a dual-drug CarboCell providing sustained release of a Toll-like receptor 7/8 agonist and a transforming growth factor-β inhibitor in preclinical tumor models in female mice.

Novel approaches to the treatment of osteoporosis

Despite the availability of efficacious treatments for fracture reduction in patients with osteoporosis, there are still unmet needs requiring a broader range of therapeutics. In particular, agents that are capable of replacing already lost bone and that also drastically reduce the risk of non-vertebral fractures are needed. Studies of rare bone diseases in humans and animal genetics have identified targets in bone cells for the development of therapies for osteoporosis with novel mechanisms of action. Here, we review these new developments, with emphasis on inhibitors of cathepsin K in osteoclasts and sclerostin in osteocytes, which are currently studied in phase 3 clinical trials.

Osteoanabolics

Osteoporosis is characterized by reduced bone mass, impaired bone quality, and a propensity to fracture. An "osteoanabolic" should be referred to any therapy that helps increase bone mass. Bone mass represents 80% of bone mechanical strength. A low bone mass therefore provides the strongest association of future risk of fracture. This review aims to discuss all available and future therapies that attempt to increase bone mass be it organic or inorganic.

Targeting sclerostin as potential treatment of osteoporosis

In recent years, study of rare bone diseases has led to the identification of signalling pathways that regulate bone formation and provided targets for the development of novel therapeutic agents to stimulate bone formation in patients with osteoporosis. Studies of two bone sclerosing dysplasias, sclerosteosis and van Buchem disease led to the identification of sclerostin, a negative regulator of bone formation. Sclerostin binds to LRP5/6 and inhibits Wnt signalling, but its precise molecular mechanism of action is not yet known. Its expression is restricted in the skeleton to osteocytes and is modified by mechanical loading and parathyroid hormone treatment. Sclerostin deficiency reproduces the findings of the human diseases in mice, while sclerostin excess leads to bone loss and reduced bone strength. An antibody to sclerostin increased bone formation dramatically at all bone envelopes in ovariectomised rats and intact monkeys, without affecting bone resorption and improved bone strength. In initial human studies, a single injection of the antibody to postmenopausal women increased serum P1NP and transiently decreased serum CTX. Clinical phase II studies with this antibody are currently underway.