Prosecuting method of treatment and diagnostic method claims

The US Supreme Court’s 2012 Mayo decision cast doubts over the patentability of certain life sciences innovations. What do recent judgments tell us about how best to seek protection for method of treatment and diagnostic method claims?

As of 2018, the Court of Appeals for the Federal Circuit has consistently found method of treatment claims eligible for patent protection, with landmark case Vanda Pharms Inc v West-Ward Pharms Int’l Ltd (887 F 3d 1117 (Fed Cir 2018)) being both cheered and criticised for appearing to guarantee patent eligibility to any claim reciting a treatment step.

Since it was issued, the Federal Circuit has treated Vanda as a foil to Mayo Collaborative Services v Prometheus Labs Inc (566 US 66 (2012)), drawing a line between patent-eligible method claims that recite administering a drug in a required, specific treatment regimen (Vanda) and patent-ineligible method claims that incidentally recite administering a drug to determine (but not necessarily act on) an improved treatment regimen (see generally Natural Alternatives Int’l Inc v Creative Compounds LLC, 918 F 3d 1338 (Fed Cir 2019); Endo Pharms Inc v Teva Pharms USA Inc, 17-1240, 17-1455, 17-1887 (Fed Cir 2019)).

The Federal Circuit’s decision in Natural Alternatives was rendered at the pleadings stage and relied heavily on generous claim constructions (proposed by the patentee) that required administering “unnatural quantities” of a natural substance to alter a human’s physiology. The court found the asserted claims patent eligible after comparing them to key qualities of the Vanda claims, reciting “a specific method of treatment for specific patients using a specific compound at specific doses to achieve a specific outcome” (Natural Alternatives, 918 F 3d at 1345-1346 (quoting Vanda, 887 F 3d at 1136)).

Although Natural Alternatives’ claims did not explicitly recite a “specific dose”, the Federal Circuit found that the claims satisfied this element in view of:

  • a claim limitation that the natural substance is administered “effective” to achieve a recited result; and dosing guidance in the specification (Id at 1346).

The court also appeared unperturbed that the claims did not address a specific patient population (Id at 1345).

Likewise, the Federal Circuit in Endo held that the asserted claims were “directed to a specific method of treatment for specific patients using a specific compound at specific doses to achieve a specific outcome” and thus patent eligible (Endo, 17-1240 at 12 (quoting Vanda, 887 F 3d at 1136)). Similar to Natural Alternatives’ claims, Endo’s claims instructed administering a drug in an effective amount (for Endo, “a lower dosage”) to achieve a recited result. While the Federal Circuit made no comment on whether Endo’s specification provided further guidance as to a “specific dose”, it found that the claim as a whole provided sufficient information on how to adjust doses. Thus, the court held that “any differences in specificity are not of a sufficient degree to convince us to conclude that the claims here should be ineligible as compared to the claims in Vanda” (Id at 14).

However, not all recent case law suggests that any method of treatment claim is eligible for patent protection. In INO Therapeutics LLC v Praxair Distrib Inc (782 Fed Appx 1001 (Fed Cir 2019)), the Federal Circuit held a series of method of treatment claims to be patent ineligible because they recited treating one patient sub-set in a standard manner (administering 20ppm inhaled nitric oxide (iNO)) while withholding treatment from another patient sub-set. The claims required identifying patients for treatment based on a natural condition: whether they had left ventricular dysfunction.

Thus, the court found that the claims covered “a method in which, for the iNO-excluded patients, the body’s natural processes are simply allowed to take place. Consequently, the claim[s] here [are] directed to the natural phenomenon” (Id). Although INO is a non-precedential opinion, it appears to signal that a method of treatment claim (or a method of diagnosis plus treatment claim) must affirmatively treat all recited patients. Perhaps more controversially, INO may conflict with the implication from Vanda that an affirmative, specific treatment step is patent eligible, regardless of whether it is novel and non-obvious.

All of this case law is worth bearing in mind as applicants look to prosecute the strongest method of treatment patents.

Key steps to prosecuting method of treatment claims in the United States

Draft method of treatment claims to recite specific treatment steps

The Federal Circuit’s analyses and holdings in Vanda, Natural Alternatives, Endo and INO highlight the importance of framing a claim to recite an active drug administration step, where the drug alters the recipient’s physiology, and further framing a claim to recite only subjects that receive the claimed treatment. This is critical when it comes to aligning a claim with Vanda and distinguishing it from Mayo. Although the holding in Vanda focuses on the specificity of various claim elements, subsequent cases have revealed that the courts may not require all elements (eg, specific patients) to appear in a given claim in order to render it eligible for patent protection. Moreover, the case law suggests a loose definition of ‘specificity’ and permits reading in guidance from the overall disclosure. In light of this permissive attitude, any method of treatment-type claim would likely be deemed patent eligible under the current case law. Still, applicants should exhibit caution by incorporating more explicit specificity into their method of treatment claims that at least parallels the specific limitations discussed in Vanda. However, in order to avoid unnecessarily disclaiming the claim scope, applicants may wish to recite more specific elements in dependent claims, while keeping their independent claims broader.

The recitation of specific, active treatment steps was further endorsed in the 17 October 2019 update to the USPTO guidance on subject-matter eligibility. This identifies three factors for determining whether a claim reciting a method of treatment or a method of prophylaxis is directed to patent-eligible subject matter. The first factor requires “particularity” (eg, by limiting a claim to recite a specific drug or class of drugs, rather than leaving the identity of the treatment open-ended). Dose limitations similarly contribute to a claim’s particularity. The second and third factors require a relevant link between the recited drug and the recited purpose of treatment or prophylaxis, and that the treatment or prophylaxis meaningfully limits the application of a natural phenomenon, respectively. The USPTO guidance indicates that fulfilling all three factors demonstrates more than the mere application of a natural law and aligns a claim with the patent-eligible claims in Vanda.

Clarify that any natural substance is administered in an unnatural way

In addition, the courts may scrutinise claims in which the administered substance occurs in nature or is commonly consumed by the intended recipients more deeply. For example, some of the claims at issue in Natural Alternatives required administering beta-alanine, which naturally occurs in small quantities in food and thus is naturally administered to humans through their diets. For this reason, it was crucial to the claims’ validity that they require administering unnaturally high amounts of beta-alanine. Natural Alternatives therefore teaches applicants to recite claim language that signifies a change from how a natural substance may be administered in nature (eg, by specifying unnatural doses or reciting an end result that occurs only with unnatural doses). Applicants could also demonstrate patent eligibility by reciting an unnatural route of administration.

Recent 101 case law for diagnostic method claims

In contrast to method of treatment claims, diagnostic claims and method of detection claims have not fared well before the Federal Circuit. For example, in Roche Molecular Sys Inc v Cepheid (905 F 3d 1363 (Fed Cir 2018)), the Federal Circuit held claims to a method of detecting mycobacterium tuberculosis using polymerase chain reaction (PCR) to be patent ineligible. The court reasoned that bacterial DNA is naturally occurring, PCR is routine and conventional, and detecting bacteria based on PCR outputs constitutes a mental step (Id at 1371).

Similarly, the Federal Circuit held diagnostic claims to be patent ineligible in Athena Diagnostics Inc v Mayo Collaborative Servs LLC (915 F 3d 743 (Fed Cir 2019)). The asserted claims in Athena recited detecting naturally occurring auto-antibodies (eg, using a radio-labelled molecule). Although Athena argued that the claims covered a new and innovative laboratory technique, the Federal Circuit agreed with Mayo that the claims were directed to a natural law – namely, the correlation between auto-antibodies and a disease state, and routine and conventional means to detect those auto-antibodies (Id at 750).

The Federal Circuit clarified that using an unnatural substance (eg, a radio-labelled molecule) does not render a claim patent eligible when the unnatural substance is part of a standard technique used “in a standard way to observe a natural law” (Id at 754–55). The court then dismissed an appeal for en banc review. Despite many judges commiserating with Athena’s concern for the future of the diagnostics industry, they stated that the courts were bound by precedent to find diagnostic claims invalid.

The judges instead called on Congress or the Supreme Court to clarify or repair the patent-eligibility standards for diagnostic method claims (see generally Athena Diagnostics Inc v Mayo Collaborative Servs, LLC, 17-2508 (Fed Cir 2019), dissents and concurrences to en banc dismissal). Although Senators Tillis and Coons have been working on proposed bill language intended to loosen the restrictions on diagnostics and detection method claims, as yet, no bill has been introduced. Meanwhile, the Supreme Court recently denied Athena’s petition for certiorari. The Federal Circuit’s non-precedential decision in Cleveland Clinic Foundation v True Health Diagnostics LLC (18-1218 (Fed Cir 2019)) applied similar logic to Athena. The claims at issue recite a method of detecting elevated myeloperoxidase (MPO) and were modelled on a patent-eligible claim, according to published USPTO guidance.

Nevertheless, the Federal Circuit identified the claims as drawn to “known methods to detect MPO levels in plasma, comparing them to standard MPO levels, and reaching a conclusion” and thus to the observation of a natural law through routine and conventional means (Id at 10). In fact, the court emphasised that “the specification and prosecution history plainly concede that each of the process steps was well-known in the art” (Id at 11). Lastly, the Federal Circuit reconciled the contradictory USPTO guidance by explicitly rejecting it, stating that “we are mindful of the need for consistent application of our case law” (Id at 13).

Key steps to prosecuting diagnostic method claims in the United States

Consider whether and when to characterise a method as ‘routine’ or ‘conventional’

Applicants often refer to techniques as routine or conventional, perhaps to briefly describe a method outside the focus of the invention or in arguments traversing a written description or enablement rejection. However, examiners and the courts may use these stipulations to find claims ineligible for patent protection. Thus, applicants should use this language sparingly and only when uncontroversial.

Treat USPTO guidance with caution

In light of the Federal Circuit’s (albeit non-precedential) decision in Cleveland Clinic, applicants should not rely on USPTO guidance solely to inform the bounds of a patent-eligible or ineligible claim. Instead, they would be better served by modelling their claims on patent-eligible claims discussed in case law and by diversifying their claim language to safeguard against further changes in the law.

Maintain pending US applications and pursue claims to a variety of invention categories

Short of inventing new processes, assay components or the like for diagnosing patients or detecting natural substances, claims exclusively reciting these types of subject matter are patent ineligible under the current law. One route to protecting patent-eligible claims may be to combine a diagnostic or detection step with a subsequent method of treatment step, ideally preceded by a method of treatment-type preamble. For example, the claims might parallel the patent-eligible Vanda claims, which recite a method of treating a disease comprising a diagnostic step (eg, genotyping) followed by a treatment regimen (eg, modified dosing) dictated by the diagnostic step.

This strategy comports with the Federal Circuit’s finding that the structurally similar (although substantively different) claims in Endo and Vanda were “legally indistinguishable” (Endo, 17-1240 at 12). Of course, applicants pursuing this approach will need to support and enable the added treatment step and its link to the diagnostic or detection method. This may add significant time and/or expense to developing the invention and the preparation of patent applications.

Applicants might also try to claim diagnostic or detection inventions through a kit claim. However, at least one district court has found these to be “method claims [to a natural phenomenon] in the guise of a device” and thus ineligible for patent protection (Esoterix Genetic Labs LLC v Qiagen Inc, 2016 WL 4555613 at *8 (D Mass, 31 August 2016) (quoting CLS Bank Int’l v Alice Corp Pty, 717 F 3d 1269, 1288 (Fed Cir 2013) aff’d 573 US 208 (2014)). Therefore, applicants electing this option should proceed with caution and pursue alternative claiming formats as well, such as the above-mentioned Vanda-like diagnosis-plus-treatment structure.

Other avenues to pursue

If applicants still want to claim the diagnostic or detection method itself, they may need to wait for legislation or a Supreme Court decision to lift the patent-ineligibility cloud from this subject matter. As a result, applicants may be tempted to keep their diagnostic or detection methods trade secrets until (and unless) the law permits patent protection. However, this tactic carries the risk of disclosure, reverse engineering or competition from others who independently make the same discovery. The trade secret route also prevents applicants from protecting their inventions in other major jurisdictions (eg, Europe), which permit in vitro detection claims, as well as claims reciting compositions for use in diagnosis.

Applicants may reap more benefits from filing an application disclosing and claiming both current patent-eligible subject matter (if available) and the diagnostic or detection methods that they hope to patent in the future. This approach offers at least three advantages. First, it secures an earlier priority date than waiting would, and guards against disclosures or uses by others. Second, and related to the first advantage, this approach frees applicants to make disclosures about their inventions (eg, to promote or sell their product), without fear of creating prior art against themselves. Third, by including claims to different invention categories (eg, methods of treatment, diagnosis and detection), applicants’ may better maximise the patent term. In particular, applications claiming different invention categories should trigger a restriction requirement, allowing the applicants to file divisional applications and avoid filing terminal disclaimers. With these advantages in place, applicants may pursue the easier, patent-eligible subject matter first while waiting to pursue diagnostic or detection method claims until future divisional applications, by which time the law may have shifted.

That said, there is no guarantee that either the Supreme Court or Congress will restore patent eligibility to method of diagnosis or detection claims. Thus, to best position themselves in this uncertain legal landscape, applicants should maintain pending applications in the United States and monitor both case law and legislative developments in order to inform their product development and patent filing strategies.

Action plan

In the aftermath of the Supreme Court’s Mayo decision and subsequent Federal Circuit rulings on subject patent eligibility, the following should be kept in mind:

  • The Federal Circuit has repeatedly found that method of treatment claims are not ineligible for patent protection under Mayo.
  • However, it is not the case that any method of treatment claim is patentable. Applicants should draft method of treatment claims to recite specific treatment steps and should specify that natural substances are administered in an unnatural way.
  • In contrast, diagnostic claims and methods of detection have fared badly at the Federal Circuit, with such claims often being invalidated for claiming unpatentable laws of nature.
  • Applicants for such claims should be careful when characterising steps as routine or conventional. They should also maintain pending US applications and pursue claims to a variety of invention categories.

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