END-STAGE RENAL DISEASE
In the U.S., according to data from the U.S. Renal Data System, there are approximately 600,000 patients with end-stage renal disease (ESRD) and the number of ESRD patients is projected to continue to rise in the future. The majority of ESRD patients, over 400,000, require dialysis. Worldwide, there are approximately 2.8 million patients with ESRD, with the majority of ESRD patients, over 2 million, requiring dialysis. Phosphate retention and the resulting hyperphosphatemia in patients with ESRD on dialysis are usually associated with secondary hyperparathyroidism, renal osteodystrophy, soft tissue mineralization and the progression of renal failure. ESRD patients usually require treatment with phosphate-binding agents to lower and maintain serum phosphorus at acceptable levels.
Aluminum-type phosphate binders were widely used in the past. However, the systemic absorption of aluminum from these agents and the potential toxicity associated with their use no longer make this type of binder a viable long-term treatment option.
Calcium-type phosphate binders are commonly used to bind dietary phosphate; however, they promote positive net calcium balance and an increased risk of metastatic calcification in many patients, especially in those patients taking vitamin D analogs and those with adynamic bone disease.
Non-calcium-based, non-absorbed phosphate binders, including sevelamer hydrochloride and sevelamer carbonate are among the most prescribed phosphate binders in the U.S. Compared to the calcium-type binders, fewer coronary and aortic calcifications have been documented, however, there is a risk of metabolic acidosis with sevelamer hydrochloride, as well as the potential for gastrointestinal problems, and sevelamer can affect concomitant vitamin K and vitamin D treatment.
Lanthanum-type phosphate binders are another alternative. Lanthanum is a rare earth element and is minimally absorbed in the gastrointestinal tract. Lower level tissue deposition, particularly in bone and liver, has been observed in animals. However, the long-term effects due to the accumulation of lanthanum in these tissues have not been clearly determined.
The need for alternative phosphate-binding agents has long been recognized, especially given the increasing prevalence of ESRD as well as shortcomings with current therapies.
NON-DIALYSIS DEPENDENT CHRONIC KIDNEY DISEASE:
It is estimated that approximately 10 to 15% of the U.S. adult population is affected by non-dialysis dependent CKD, or NDD-CKD, a condition generally characterized by greater than 50% reduction of normal kidney function. In addition, elevated levels of serum phosphorus become more prevalent in Stages 3 to 5 NDD-CKD patients. Several studies have shown that higher serum phosphorus concentrations may be associated with increased mortality and morbidity in CKD, however, no phosphate binders are currently FDA approved for NDD-CKD.
Iron deficiency anemia, which develops early in the course of CKD and worsens with disease progression, is extremely prevalent in the NDD-CKD population and is associated with fatigue, lethargy, decreased quality of life and is also believed to be associated with cardiovascular complications, hospitalizations, and increased mortality. Based on data contained in a 2009 publication in the Journal of the American Society of Nephrology, it is estimated that over 1.5 million adults with NDD-CKD in the U.S. alone are also afflicted with iron deficiency anemia. To combat this anemia, iron replacement therapy is essential to increase iron stores, such as ferritin and TSAT levels, and raise hemoglobin levels. Currently available oral iron supplements are associated with limited efficacy and dose-limiting tolerability issues.
No oral iron agents are currently FDA approved to treat iron deficiency anemia in NDD-CKD. Erythropoiesis-Stimulating Agents (ESA) and IV iron are not frequently administered in NDD-CKD due to both the FDA warning label of potential cardiovascular risk for ESAs and logistical complications associated with administering IV medicines in office settings which lack the necessary facilities, such as emergency equipment and/or emergency medical access. Consequently, the NDD-CKD patient population remains underserved.
Zerenex has the potential to be an effective and safe treatment for lowering and/or maintaining serum phosphorus levels, and treating iron deficiency, in patients with ESRD and NDD-CKD.