Cinacalcet Compound Patent Obvious and Anticipated

In Amgen Canada v. Mylan Pharmaceuticals ULC, 2015 FC 1244, a prohibition application under the PM(NOC) Regulations, Justice Phelan recently held that Amgen’s Canadian Patent 2,202,879 was obvious and anticipated.

Claim 1 of the 879 Patent is directed to trillions of calcimimetic compounds useful in modulating the activity of calcium ion receptors and for treating related diseases. Claim 5 of the 879 Patent, the only clam in issue, is directed cinacalcet and its salts.

No selection invention

Amgen’s conceded that cinacalcet was disclosed in the prior art but attempted to support the validity of claim 5 by arguing that cinacalcet was a selection invention because it has unexpected utility over the prior art genus as well as the former lead compound.

Justice Phelan rejected Amgen’s argument, holding that Amgen had failed to establish a substantial an unexpected advantage of cinacalcet. The mechanism by which cinacalcet works was disclosed in the prior art and there was nothing in the potency of cinacalcet that was surprising. In fact, 47 of the 61 compounds disclosed in Table 1 of the 879 Patent were more active than cinacalcet. The potency of cinacalcet was also within the range disclosed in the prior art.


A prior art application describing cinacalcet was filed in 1993 but only issued in 2011, after the 879 Patent has issued. Amgen argued that the earlier filed application was not prior art because it only issued after the 879 Patent. Justice Phelan rejected this argument, holding that Amgen had conflated the publication and issue date. Following Baker Petrolite, the critical date is the date of disclosure to the public. Since the publication of the earlier application preceded the filing date of the 879 Patent, it was prior art.


Following the test set out in Plavix, Justice Phelan held that the inventive concept of claim 5 is cinacalcet per se, not cinaclacet’s unexpected activity as a modulator of the calcium-sensing receptor. Justice Phelan further held that there was no difference between the inventive concept and the prior art. Cinacalcet, its structure and function, had been disclosed in the prior art and claim 5 merely gave further specificity. Alternatively, if there was a difference between the inventive concept and the prior art, the skilled person would have found cinacalcet using known screening assays and would only have to test 200 molecules.

Given the Court’s findings on novelty and obviousness, it was not necessary to address Mylan’s allegation of double patenting.

A copy of the decision may be found here.