In a “Report and Recommendation on Defendants’ Joint Motion To Dismiss,” U.S. Magistrate Judge Cabell of the U.S. District Court for the District of Massachusetts determined that TB test kit claims do not satisfy the patent eligibility requirement of 35 USC § 101, but declined to reach the same conclusion with regard to related method claims. The decision was issued in Oxford Immunotec Ltd. v. Qiagen, Inc., where Oxford has asserted that Qiagen’s test kits for diagnosing TB infection in vitro infringe a number of its patents.

The TB Test Kit Claims At Issue

Three TB test kit claims from three different patents were at issue:

Claim 7 of U.S. Patent 7,632,646  (issued December 15, 2009):

7. A kit for diagnosing infection in a human host by, or exposure of a human host to, a mycobacterium that expresses ESAT-6, comprising a panel of eight peptides represented by SEQ ID NOS: 1 to 8.

Claim 17 of U.S. Patent No. 7,901,898 (issued March 8, 2011):

17. A kit for diagnosing infection in a human host by, or exposure of a human host to, a mycobacterium that expresses ESAT-6, comprising a peptide represented by SEQ ID NO: 1.

Claim 17 of U.S. Patent No. 8,216,795 (issued July 10, 2012):

17. A kit for in vitro diagnosis which distinguishes between (a) exposure of a human host to Mycobacterium tuberculosis and (b) vaccination of the human host with BCG, comprising a peptide panel, wherein the peptide panel comprises peptide SEQ. ID. No: 1.

The Magistrate Judge found the kit claims to be ineligible despite the ability of the recited peptides to “perform differently than peptides contained in an intact ESAT-6 strand” and despite the fact that the recited peptides are “synthetically created.” Citing Myriad, the Magistrate Judge focused on the fact that it was “undisputed that the peptides have not been changed beyond the act of isolation.” As such, “the isolated peptides are products of nature.”

The TB Test Method Claims At Issue

Three TB test method claims from three different patents were at issue:

Claim 1 of U.S. Patent No. 8,507,211 (issued August 13, 2013):

1. A method of in vitro diagnosis of Mycobacterium tuberculosis infection in a host, comprising (a) keeping a population of T cells isolated from said host in contact with a peptide panel comprising one or more epitopes contained within peptide SEQ ID NO: 1, and (b) detecting a recognition response by the T cells to the peptide panel.

Claim 1 of U.S. Patent No. 9,005,902 (issued April 14, 2015)

1. A method of in vitro diagnosis of Mycobacterium tuberculosis infection in a host, comprising (a) keeping a population of T cells isolated from said host in contact with a peptide panel comprising one or more epitopes contained within one or more peptides selected from the group consisting of: SEQ ID NO: 1, peptide SEQ ID NO: 2, peptide SEQ ID NO: 3, peptide SEQ ID NO: 4, peptide SEQ ID NO: 5, peptide SEQ ID NO: 6, peptide SEQ ID NO: 7, and peptide SEQ ID NO: 8, and (b) detecting a recognition response by the T cells to the peptide panel.

Claim 6 of U.S. Patent No. 8,617,821 (issued December 31, 2013):

6. An assay for identifying Mycobacterium tuberculosis-specific immediate effector T cells in a subject, comprising: (a) providing a sample from said subject containing T cells; (b) exposing said T cells to an immunogenic amount of a peptide subfragment of ESAT-6 that contains a CD8+ epitope; (c) incubating said T cells for a period of time which is not sufficient to effect differentiation of quiescent T cells to immediate effector T cells; and (d) determining whether said T cells are activated by said peptide subfragment by measuring secretion of a cytokine from said T cells, wherein activation of said T cells identifies the presence of Mycobacterium tuberculosis-specific immediate effector T cells in said subject.

The Magistrate Judge found that the method claims relate to a law of nature: “which specific peptides in ESAT-6 are most likely to induce a recognition response by the T-cells of patients who have TB without creating false positive responses by the T-cells of those who have merely been vaccinated.” Nevertheless, the Magistrate Judge determined–at least for this preliminary stage–that “the patented invention improves on existing methods for diagnosing TB by making diagnosis more convenient, less dependent on a physician’s subjective interpretation of results, and more accurate,” and so could be patent-eligible.

The Magistrate Judge summarized his findings as follows:

At this early juncture, the Court concludes that the in vitro aspect of the plaintiff’s tuberculosis test is an “inventive concept” because it improves on prior methods of detecting tuberculosis infection. It follows that the method claims, which describe the in vitro test, are potentially drawn to patentable subject matter. In contrast, the kit claims only describe the peptide panel itself and do not involve the “inventive concept” of an in vitro test, and thus are not drawn to patentable subject matter.

Will the method claims survive further scrutiny?