OPKO Health, Inc., a multi-national biopharmaceutical and diagnostics company, has completed the acquisition of Cytochroma Inc. (Markham, Canada). Cytochroma's lead products include CTAP101 capsules, a vitamin D prohormone to treat secondary hyperparathyroidism (SHPT) in patients with stage 3 or 4 chronic kidney disease (CKD) and vitamin D insufficiency, and Fermagate tablets, a new and potent non-absorbed phosphate binder to treat hyperphosphatemia in CKD patients on chronic hemodialysis.

CTAP101 capsules have been shown in a phase 2b clinical trial to effectively and safely treat SHPT and the underlying vitamin D insufficiency in pre-dialysis patients. Vitamin D insufficiency arises in CKD due to the abnormal upregulation of CYP24, an enzyme which destroys vitamin D and its metabolites. Studies in CKD patients have demonstrated that currently available over-the-counter and prescription vitamin D products cannot reliably raise blood vitamin D prohormone levels and effectively treat SHPT. CTAP101 Capsules are in phase 3 clinical trials in the United States.

The new phosphate binder, Fermagate tablets, has been shown to be safe and effective in treating hyperphosphatemia in phase 2 and 3 trials in CKD patients undergoing chronic hemodialysis. Hyperphosphatemia contributes to soft tissue mineralization and affects approximately 90% of dialysis patients. Dialysis patients require ongoing phosphate binder treatment to maintain normal serum phosphorus levels. Opko is working with US and European regulatory authorities to finalize the remaining phase 3 clinical programme for Fermagate tablets.

CKD is a condition characterized by progressive decline in renal function. The kidney is normally responsible for excreting waste and excess water from the body and for regulating various hormones. CKD is classified in five stages — mild (stage 1) to severe (stage 5) disease — according to glomerular filtration rate. According to the National Kidney Foundation, CKD afflicts over 26 million people in the US, including more than eight million patients with stage 3 or 4 CKD. In stage 5, kidney function is minimal to absent and patients require regular dialysis or a kidney transplant for survival.

Vitamin D insufficiency is a condition in which blood levels of vitamin D prohormones, collectively known as 25-hydroxyvitamin D, are inadequate. An estimated 70-90% of CKD patients have vitamin D insufficiency which can lead to SHPT and its debilitating consequences.

SHPT is a condition commonly associated with CKD in which the parathyroid glands secrete excessive amounts of parathyroid hormone (PTH). SHPT arises as a result of vitamin D insufficiency or impaired kidney function. Prolonged elevation of blood PTH causes excessive calcium and phosphorus to be released from bone, leading to elevated serum calcium and phosphorus levels, softening of the bones (osteomalacia) and calcification of vascular and renal tissues. SHPT affects 40-60% of patients with stage 3 or 4 CKD and approximately 90% of patients with stage 5.

Hyperphosphatemia, or elevated serum phosphorus, is common in dialysis patients and tightly linked to the progression of SHPT. The kidneys provide the primary route of excretion for excess phosphorus absorbed from ingested food. As kidney function worsens, serum phosphorus levels increase and directly stimulate PTH secretion. Stage 5 CKD patients must reduce their dietary phosphate intake and usually require regular treatment with phosphate binding agents to lower serum phosphorus to meet the recommendations of the National Kidney Foundation's Clinical Practice Guidelines that serum phosphorus levels should be maintained at or below 5.5 mg/dL.