Inecalcitol is a vitamin D analogue in development by Hybrigenics against prostate cancer, in combination with existing treatments to improve their efficacy and/or to reduce their side effects.

Inecalcitol has been optimized to be more potent than calcitriol, the naturally active metabolite of vitamin D, to slow down proliferation of cancerous cells as well as hyper-proliferating normal cells, such as cells from skin affected by psoriasis , or from benign (non-cancerous) hypertrophic prostate.

Initially, vitamin D has been discovered for its major role in regulating calcium absorption from the gut, storage in mineral form in the bones, and excretion by the kidney. This is the reason why it is highly effective to prevent rickets in infants. However, vitamin D and calcitriol, its naturally active form, can cause hypercalcemia at high or frequently repeated doses; in turn, hypercalcemia can cause kidney toxicity by accumulation of calcium-containing micro-crystals and heart and muscle dysfunction by impairing contractions. Inecalcitol has also been optimized to have much less effect on calcemia, and therefore to be much less toxic than calcitriol.

Inecalcitol is currently in Phase II escalating dose tolerance study in prostate cancer patients, to determine the maximal tolerated dose which can be given orally every day. Then, Hybrigenics will perform a Phase III registration trial to compare the efficacy of existing treatment of prostate cancer on overall survival with or without inecalcitol.

Psoriasis in dermatology, and hyperparathyroidism , a condition resulting from chronic kidney disease, are two other diseases for which a few other optimized vitamin D analogues have already been successfully developed, registered and marketed. Inecalcitol will be proposed to companies specialized in these therapeutic areas for licensing-out in these indications.