Friday, June 23, 2006

Lemley comment on Metabolite case

Patently-O has a quote from Mark Lemley concerning the Metabolite case:

Don't believe everything you read in dissents. I represented the patent owner in this case. The idea that the patent could be infringed merely by "thinking about" a correlation is a misunderstanding caused by lack of knowledge of patent law. The claimed process had two steps (1) drawing blood and assaying it for total homocysteine, and (2) correlating an elevated level of total homocysteine with a vitamin deficiency. Step 2 could be performed mentally, but that doesn't mean that patent could be infringed just by thinking.

Dennis Crouch responded:

Mark, I agree that the dissent's description of the claim in question was not correct. But, yours might not be correct either. The claim requires "assaying a body fluid for an elevated level of total homocysteine; and correlating an elevated level of total homocysteine in said body fluid with a deficiency of cobalamin or folate." I don't see any blood draw requirements.

***
The patent at issue is US 4,940,658.

Claim 13 states:

A method for detecting a deficiency of cobalamin or folate in warm-blooded animals comprising the steps of:

assaying a body fluid for an elevated level of total homocysteine; and

correlating an elevated level of total homocysteine in said body fluid with a deficiency of cobalamin or folate.

Claim 1 is directed to a method of assaying:

A method of assaying for the amount of one or more sulfhydryl amino acid species present in a given sample, said method comprising:

(a) combining said sample with an internal reference standard comprising a known amount of each sulfhydryl amino acid species to be assayed, labelled with a suitable marker;

(b) adding sufficient reducing agent to insure randomization of the labelled and unlabelled sulfhydryl amino acids present;

(c) measuring the relative amounts of labelled and unlabelled sulfhydryl amino acid present for each species with a mass spectrometer;

(d) calculating the ratio of labelled to unlabelled sulfhydryl amino acid present for each species; and

(e) deriving the amount of unlabelled sulfhydryl amino acid present for each species in said given sample.

The only mention of "assaying" outside of the claims is in the sentence:

Accordingly, the present invention provides a preferred method of assaying the total cysteine and/or total homocysteine in a given sample using mass spectroscopy.

Although Dennis Crouch wrote: An assay is simply a test, and this particular claim provides no limit on what the assay could be, the text in the specification suggests that the disclosure is an assay using mass spectrometry [the inventors mistakenly state "spectroscopy" but mass spectrometry is not a "spectroscopy."] However, the inventors speak of a preferred method, so that the assay is directed to measuring the amount of cysteine or homocysteine, by whatever approach.

The word "correlating" appears only in claims 13 and 14, and not in the specification itself.

Within the specification, one has:

It has now been discovered that the clinical spectrum of cobalamin deficiency is much broader than previously recognized and that many cobalamin-deficient patients are not anemic, or only moderately anemic; that in many cases their red blood cells are not macrocytic, or only moderately macrocytic; that in many cases a variety of neurologic abnormalities other than peripheral neuropathy and ataxia are present; and that in many cases the serum cobalamin level is only slightly decreased and may actually be normal, even with the improved assays above using purified intrinsic factor. Accordingly, there is a need for an improved assay for cobalamin deficiency, preferably one in which cobalamin deficiency can be distinguished from folate deficiency. [IPBiz: !]

The first sentence of the "summary of invention:"

It has now been discovered that an elevated level of total homocysteine in tissues of warmblooded animals correlates both with cobalamin deficiency and with folic acid deficiency; an animal with elevated levels of total homocysteine is likely to have one or both deficiencies but the assay does not distinguish between the two.

Later in the summary:

It has been discovered that elevated levels of homocysteine in body tissue correlate with decreased levels of cobalamin and/or folic acid in said body tissue. Accordingly, assays for homocysteine can be used to determine the presence or absence of cobalamin and/or folic acid deficiency in warm-blooded animals. Suitable assays for this purpose include any assays capable of determining levels of homocysteine in body tissues, preferably body fluids, preferably urine or blood. Serum and plasma are particularly preferred.

The use of the word "or" in claim 13 becomes interesting.

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