Patent eligible Laboratory methods

Yoshiya Nakamura | July 13, 2016

Rapid Litigation Management Ltd. v. CellzDirect, Inc.

July 5, 2016

Before Prost, Moore and Stoll.  Opinion by Prost.


Patented claims at issue were directed to a method of producing a desired preparation of hepatocytes (liver cells) useful for laboratory tests such as drug safety tests.  The claimed process was invented based on the discovery that liver cells are capable of surviving multiple freeze-thaw cycles, which provides desired pool samples of hepatocytes from multiple donners.  The district court held that the claims were invalid under 35 U.S.C. §101.  CAFC vacated the decision, holding that the claimed process is not directed to a patent-ineligible concept.


近年最高裁判決の下、自然法則または自然現象を優位に超える特徴をクレームに記載しなければ特許対象にはならない。地裁は肝細胞が冷凍保存可能であることはその細胞の自然能力の発揮にすぎず、本特許の方法は自然法則の利用を優位に超える特徴を記載していないとして同特許を無効にした。高裁はその地裁判決を破棄し、従来の知見反して肝細胞の冷凍を2回以上繰り返す工程を記載した本特許の方法は従来の方法にはない利点があるから特許可能対象であると判示した。複数回の冷凍保存を行うことができるという科学的発見に基づくシンプルな発明コンセプトであるが、新規で有用な結果をもたらす方法は特許対象になりえることが示された。このケースは発見を利用する発明を新規な「方法」として記載することで特許対象になり得ることを示しているが、その肝細胞を「プロダクト」としてクレームした場合は自然物の寄せ集めであり特許対象になりえないことも示唆された(Funk Bros判決参照)。一方で、101条の特許対象要件の判断において従来技術との対比が重要な意味を持ち得ることを示した判決でもある。


Claim 1 representative of the ’929 patent (U.S. Patent No. 7,604,929):

  1.  A method of producing a desired preparation of multi-cryopreserved hepatocytes, said hepatocytes being capable of being frozen and thawed at least two times, and in which greater than 70% of the hepatocytes of said preparation are viable after the final thaw, said method comprising:

(A) subjecting hepatocytes that have been frozen and thawed to density gradient fractionation to separate viable hepatocytes from nonviable hepatocytes,

(B) recovering the separated viable hepatocytes, and

(C) cryopreserving the recovered viable hepatocytes to thereby form said desired preparation of hepatocytes without requiring a density gradient step after thawing the hepatocytes for the second time, wherein the hepatocytes are not plated between the first and second cryopreservations, and wherein greater than 70% of the hepatocytes of said preparation are viable after the final thaw.

Steps of freezing cells for preservation and thawing them to recover have been a well-known cryopreservation technique to keep the source of cells for later use such as laboratory tests.  Hepatocytes (liver cells) have a short lifespan, and the number of available cell donners is limited.  Making a pool of frozen liver cells from different donors would be useful to prepare a group of cells representing average liver cells.  However, the number of viable liver cells after the cryopreservation was limited.  Because of the poor recovery rate, it was understood that liver cells could be frozen only once and recovered viable cells were only for immediate use.  The recovered, but unused cells were discarded.  Despite the common knowledges, the inventors of the ’929 patent have found that liver cells are capable of surviving multiple freeze-thaw cycles, and applied this discovery to improve the conventional method to be a useful method for the “desired preparation of hepatocytes” by refreezing only viable cells after the first freeze-thaw cycle for later use.

The district court found the patented method invalid under 35 U.S.C. §101 as holding that the method was simply directed to the discovery of law of nature, that is, liver cells are capable of surviving multiple freeze-thaw cycles.

As an answer to the question in “step 1” of the Mayo-Alice tests as to whether the claim is directed to exceptions of patent eligible subject matter, CAFC noted:

It is enough in this case to recognize that the claims are simply not directed to the ability of hepatocytes to survive multiple freeze-thaw cycles. Rather, the claims of the ’929 patent are directed to a new and useful laboratory technique for preserving hepatocytes. This type of constructive process, carried out by an artisan to achieve “a new and useful end,” is precisely the type of claim that is eligible for patenting. Alice, 134 S. Ct. at 2354 (quoting Gottschalk v. Benson, 409 U.S. 63, 67 (1972)). .. They employed their natural discovery to create a new and improved way of preserving hepatocyte cells for later use.

CAFC thus held that the patented method easily passed the question of step 1.

Regarding the “significant more” question in “step 2” of the Mayo/Alice tests, CAFC noted that the claimed method “applies the discovery that hepatocytes can be twice frozen to achieve a new and useful preservation process” as there are a number of benefits from the refreeze-thaw technique such as to eliminate the discard of unused cells and provide useful pool samples in advance and preserving them for later use.

CAFC distinguished this case from Mayo by noting that the invalidated diagnostic claims only added knowledge of the natural law to “already being performed” steps such as administering a drug, measuring metabolite levels, and adjusting dosage, and thus were insufficient to pass the question of step 2.  Unlike Mayo, CAFC viewed the patented laboratory method here as claiming “not simply an observation or detection of the ability of hepatocytes to survive multiple freeze-thaw cycles,” but directed to a useful “end result,” i.e., the “new and improved technique, for producing a tangible and useful result, falls squarely outside those categories of inventions that are ‘directed to’ patent ineligible concepts.”

CAFC further noted that although each step of freezing, thawing and separating cells was known in the art, but this does not necessarily make the method unpatentable, because, when viewed as a whole, “a new combination of steps in a process may be patentable even though all the constituents of the combination were well known and in common use before the combination was made” (citing Diehr).  Here, CAFC found that the claimed process of “preserving hepatocytes by repeating those steps was itself far from routine and conventional.”

While confirming that “patent-eligibility does not turn on ease of execution or obviousness of application,” CAFC mentioned patentee’s teaching away arguments:

We made similar observations earlier in this litigation, noting that “the prior art taught away from multiple freezings,” as “[a] single round of freezing severely damages hepatocyte cells and results in lower cell viability.” … Repeating a step that the art taught should be performed only once can hardly be considered routine or conventional. This is true even though it was the inventor’s discovery of something natural that led them to do so. Just as in Diehr, it is the particular “combination of steps” that is patentable here.

CAFC distinguished this case from the decision in Funk Bros which held that a mixture of different bacterial species from nature was not patent eligible because “[e]ach species has the same effect it always had.”  It is true that hepatocytes are still hepatocytes maintaining the same functions even after the repeated freeze-thaw steps.  CAFC rejected the argument and noted that the claims at issue were “a new and useful process of creating that pool, not to the pool itself.”

Take Away

Always consider method claims reaching any benefits or advantages (new end results) which prior art could not.

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