On July 17th 2014, Amgen announced positive Phase 3 results for AMG-416 (formerly known as velcalcetide) for the treatment of secondary hyperparathyroidism (SHPT) in patients with chronic kidney disease (CKD) receiving hemodialysis (HD).

First, a bit of background on SHPT it is a disorder that develops early as an adaptive response to declining kidney function when the parathyroid glands increase the production of parathyroid hormone (PTH) in an effort to maintain normal levels of serum calcium and phosphorus. Ultimately, excess PTH production proves inadequate for maintaining normal serum calcium and phosphorous levels, which in turn can lead to significant clinical consequences. AMG-416 is being developed as a calcimimetic agent administered intravenously, which would be the first IV calcimimetic to the market. It is designed to bind and activate the calcium-sensing receptor on the parathyroid gland, thereby causing decreases in PTH.

Amgen obtained AMG-416 as part of the acquisition of KAI Pharmaceuticals, Inc. in July 2012 and these are the first results to be reported from the Phase 3 program - analysis of the data presented shows that the study met primary and all secondary endpoints. 75.3 percent of patients achieved a > 30 percent reduction from baseline in PTH compared with 9.6 percent in the placebo arm, a statistically significant result. Secondary endpoints included the percent change from baseline in serum phosphorus (P) concentration (mean changes of -9.63 percent and -1.60 percent among patients in the AMG-416 and placebo arms, respectively) and corrected calcium (cCa) concentration (mean changes of -6.69 percent and 0.58 percent among patients in the AMG-416 and placebo arms, respectively). Both of these secondary endpoint results were statistically significant.1

The TreatmentTrends®: Nephrology (US) Q2 2014 report published in June 2014 focuses on the management of SHPT and provides insights into physician perceptions of SHPT, based on primary market research of 203 U.S. nephrologists, and I thought I would share some findings from the report that highlights the potential opportunity for manufactures in this space. The report asks physicians for their perceived use of PTH modifiers such as nutritional vitamin D (NVD) products, active vitamin D (AVD) products, and calcimimetic agents such as Sensipar, in addition to other areas of nephrology, including phosphate binders, ESAs and IV/oral iron, but we will discuss these other areas at a later point in time.

In the PTH modifier market, Amgen's Sensipar is indicated for the treatment of SHPT in patients with CKD on dialysis and is taken orally. According to Amgen's 2013 annual report, Sensipar generated sales in excess of $1 billion in 20132 and according to Amgen's recent press release, total Sensipar sales increased 15% for the second quarter of 2014 versus the second quarter of 2013.3 In TreatmentTrends®: Nephrology (US) Q2 2014, surveyed nephrologists reported that nearly 40 percent of their HD patients and over 30 percent of their peritoneal dialysis (PD) patients were on Sensipar. However, after reviewing AMG-416's product profile, surveyed nephrologists estimated 36 percent of their dialysis patients as likely candidates for AMG-416 treatment, based on AMG-416's Phase 2 data alone. We are looking forward to how the positive findings from the Phase 3 trial will change nephrologists perceptions of AMG-416 in our TreatmentTrends®: Nephrology (US) Q3 2014 report, scheduled to publish in September 2014.

Assuming FDA approval, it will be interesting to see if AMG-416 stands to gain patient share at the expense of Sensipar, given the more convenient dosing option with AMG-416 for dialysis patients. Or, perhaps this was Amgen's plan all along to develop a new product to extend the patent life of their PTH modifier business given Sensipar's patents are expiring in 2015 and 2016 in the U.S.2

The report also asks nephrologists a series of barriers to increased Sensipar use and patient non-compliance was cited second most often by surveyed nephrologists, and for patients who receive dialysis treatment three times a week in the United States, things are looking positive for AMG-416 as an effective calcimimetic agent that can be administered intravenously with HD to help treat SHPT, which may improve compliance similar to the high perceived compliance of ESAs in the dialysis setting.

Renal treatments are interrelated and should use of calcimimetics increase with greater compliance with AMG-416, it will interesting to see what impact in use, if any, it will have on some of the other renal medications, most predominately phosphate binders and AVD. Today, we know that Sensipar may also be sometimes used to treat phosphorous, calcium and PTH and perhaps binder and AVD use will ultimately be impacted as well with greater use of calcimimetics. The chart from TreatmentTrends®: Nephrology (US) Q2 2014 below shows some of the reasons why nephrologists use Sensipar.

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