As we learned in chapter 3, a patentable invention must satisfy four substantive requirements. It must be patent eligible. It must be useful. It must be new. And it must not have been obvious. These requirements apply to the claimed invention per se. In other words, it is the invention itself that must be patent eligible, useful, new, and nonobvious.
For an invention to be patented, though, the patent document itself must meet additional substantive requirements. These requirements include written description, enablement, definiteness, and best mode. The written-description, enablement, and definiteness requirements, in particular, present special challenges to those patenting biotech and pharmaceutical inventions.
For a claimed invention, it is not enough that the patent specification discloses a hoped-for property or result. There must be more.
The U.S. patent statute requires that the patent specification contain a written description of the invention. For a description to satisfy this requirement, it must permit one skilled in the art to know the identity of the invention purportedly described. It must demonstrate to the skilled person that the inventor was in possession of the invention as of the patent application’s filing date—if not physically, then intellectually.
Written-description determinations hinge on certain factual considerations. These include, for example, the extent of existing knowledge in the relevant art and the predictability of the aspect of invention at issue. So, for example, for an invention in a predictable technology, a narrow disclosure might very well satisfy the written-description requirement with respect to a broad claim. In an unpredictable technology, however, a narrow disclosure would be less likely to satisfy the written-description requirement for a broad claim, as the skilled person would have been less likely to deem the inventor in possession of the broadly claimed invention.
Typically, for inventions such as therapeutic and diagnostic compounds, the patent specification must provide the compound’s structure to satisfy the written-description requirement. Physically depositing samples such as cell lines, antibodies, and other biomolecules with a depository such as the American Type Culture Collection (ATCC) is another way to satisfy the written-description requirement.
EXAMPLE 4.1
Claim 1 of a U.S. patent provides a peptide that has a length of twenty to thirty amino acid residues and that specifically inhibits human Kinase X.
The underlying discovery is of human Kinase X and its role in tumor development. The invention therefore has potential use as an antitumor drug.
The specification gives no examples of the claimed peptide and gives no guidance as to its structural features or methods for developing it. It merely states that the peptide must have the length and inhibitory function recited in the claim.
In this scenario, the specification does not show that the inventor was in possession of the claimed peptide. Rather, it merely states the hoped-for feature of a peptide having an as-yet undefined structure. Hence, the written-description requirement would not likely be satisfied.
Here, though, the specification gives a detailed description of the consensus sequence required for inhibitory activity against Kinase X and the amino acid residues permitted in the nonconsensus positions.
In this scenario, the detailed structural information shows the inventor’s possession of the claimed peptide. Thus, the written-description requirement would likely be satisfied.
EXAMPLE 4.3
Claim 1 of a U.S. patent provides an antibody that specifically binds to Antigen X (AgX). Detecting AgX is useful for, among other things, diagnosing certain metabolic disorders.
The specification discloses the full structure of AgX such that a skilled person could easily produce and use it to generate antibodies that specifically bind to it.
The claimed antibody need only bind to AgX, without performing any function beyond that. The written-description requirement would likely be satisfied for claim 1.
EXAMPLE 4.4
Claim 1 of a U.S. patent provides an antibody that specifically binds to Antigen Y (AgY) and lyses HIV-infected cells.
The specification discloses the full structure of AgY, such that a skilled person could easily produce and use it to generate antibodies that specifically bind to it. However, the specification provides no examples of the claimed antibody, nor any guidance as to how to achieve lysis of HIV-infected cells.
In this scenario, the specification does not show possession of the claimed antibody, and the written-description requirement would not likely be satisfied.
In addition to providing a written description of the claimed invention, the patent specification must also enable the invention.
There has been controversy over whether the enablement and written-description requirements are in fact distinct. Both arise from the same sentence of the U.S. patent statute. Steps that can satisfy the written-description requirement—such as providing nucleic acid and amino acid sequences in the specification or making biological deposits to the ATCC—can also satisfy the enablement requirement, depending on the facts. Despite this overlap, the two requirements differ and must be satisfied independently.
According to the quid pro quo requirement discussed in chapter 1, an inventor must disclose her patented invention to the public in exchange for the powerful exclusionary right that is the patent. This act would be an empty gesture unless the disclosure enabled others to practice the invention. The enablement requirement ensures that this happens.
To satisfy this requirement, the specification must show a skilled person how to make and use, or practice, the invention without undue experimentation. It is not enough for a specification to disclose a mere starting point for further research that might lead to a desired invention.
Enablement is defined as of the patent application’s filing date. Also, since showing how to use the invention is required for enablement, it follows that a specification cannot enable an invention that has no use.
Determining whether undue experimentation is needed requires weighing the relevant facts. There is no universal requirement as to which facts must be weighed in each instance or how they must be weighed. However, courts have suggested a number of factors helpful in this regard. There are eight factors, in particular, that are frequently used in resolving enablement questions. These are commonly known as the Wands factors, based on the Federal Circuit’s 1988 In re Wands decision. They include claim breadth, the nature of the invention, the state of the prior art, the level of ordinary skill, the level of predictability in the art, the amount of direction in the disclosure, the existence of working examples, and the amount of experimentation needed to practice the invention based on the disclosure.
Claim 1 of a U.S. patent provides a method for treating cardiac ischemia in an afflicted human subject. It comprises intravenously administering autologous myoblasts coated with a humanized antibody bispecific for (i) an antigen unique to myoblasts, and (ii) an antigen unique to target cardiac cells.
The specification discloses procedures for isolating autologous myoblasts and treating them with bispecific antibodies. The specification also discloses the amino acid sequences of several such antibodies useful for this method and the particular epitopes to which the antibodies bind.
However, the specification does not give any guidance as to how many coated myoblasts are to be intravenously administered, under what conditions, and according to what regimen. In particular, among the many things not disclosed in the specification is the dosing regimen needed to ensure that the myoblasts reach their target in sufficient numbers, differentiate in a way that repairs ischemia, and don’t migrate or differentiate in any other way.
Assuming that the absence of dosing guidance would necessitate undue experimentation to practice the claimed method, the enablement requirement is not met. The fact that a skilled person could make the coated myoblasts without undue experimentation does not change the result—the claimed method is still not enabled.
EXAMPLE 4.6
Claim 1 of a U.S. patent provides a method for treating a human subject afflicted with rheumatoid arthritis. It comprises administering Antibody X (AbX) in a manner effective to treat the rheumatoid arthritis without increasing the subject’s risk of viral infection.
The patent specification provides the amino acid sequence of AbX such that a skilled person could easily make it. However, the specification does not provide any dosage information for administering AbX. For example, no information is given as to how much AbX to administer per kilogram of subject body weight, what administration route to use, how often administration should occur, or over what duration administration should occur.
Assuming that arriving at an effective administration scheme would require undue experimentation, the enablement requirement would not be met for claim 1.
Here, though, the specification provides a specific dosing regimen for AbX. In one experimental example, 50 mg of AbX is administered subcutaneously as an initial dose, followed by 25 mg of AbX subcutaneously once per week for twelve weeks. Meanwhile, the specification discloses AbX simply as an anti-TNF antibody having a human Fc region and a humanized murine Fab region. No information is given as to the required antigen-binding affinity, sequence, or epitope, and no guidance is given as to how to arrive at this information. Assume, here, that the steps needed to determine such information would constitute undue experimentation.
Even though the details of AbX administration are provided, the absence of the structural information needed to make AbX means that claim 1 is not enabled.
EXAMPLE 4.8
Assume the same facts as in example 4.6. Again, the claimed method requires administering AbX in a manner effective to treat rheumatoid arthritis without increasing the subject’s risk of viral infection. The specification describes the amino acid sequence of AbX such that a skilled person could easily make it.
Now, however, the specification also provides dosage information for administering AbX. For example, it provides information as to how much AbX to administer per kilogram of subject body weight, what administration route to use, how often administration should occur, and over what duration administration should occur. As a result, arriving at an effective administration scheme would not require undue experimentation.
Given these facts, the enablement requirement would likely be met for claim 1.
As we know from chapter 1, a patent claim must set forth the boundaries of the invention. More precisely, the patent law requires the claims to particularly point out and distinctly claim the invention. A claim’s scope cannot be ambiguous or vague when read in light of the specification.
Although seldom a basis for invalidating an issued patent, this definiteness requirement is still vital to informing others what they are not at liberty to practice absent permission from the patent holder. The requirements of definiteness and the principles of claim construction (covered in chapter 2) are related yet distinct.
In theory, virtually any claim term can be indefinite under the right—or wrong—circumstances. Certain terms used in the biotech and pharmaceutical fields, though, are particularly susceptible to indefiniteness unless the specification sufficiently explains them. Examples of those terms include homologous (regarding nucleotide and amino acid sequences), functional (regarding compound analogs), sufficient (regarding enzyme activity and drug efficacy), and variant (regarding structural analogs of biomolecules).
EXAMPLE 4.9
Claim 1 of a U.S. patent provides a lipid vesicle suitable for drug delivery. The claimed vesicle has a defined composition and a diameter of 200 nm ± 20 nm.
The specification describes Method X and Method Y, two known methods for measuring lipid vesicle diameters. Method X typically yields vesicle diameter measurements twice as large as those obtained using Method Y. Neither claim 1 nor the specification states whether the recited diameter is determined using Method X or Y (or another method, for that matter).
Given this uncertainty, claim 1 is likely indefinite. Otherwise, claim 1 would, in effect, encompass at least two inventions. The first would be a lipid vesicle having a diameter of 200 nm ± 20 nm as measured by Method X. The second would be a lipid vesicle having this diameter as measured, instead, by Method Y. For at least this reason, claim 1 would fail to inform others what they are not at liberty to do absent permission from the patent holder.
EXAMPLE 4.10
Here, though, claim 1 provides a lipid vesicle having, in relevant part, a diameter of 200 nm ± 20 nm as measured by Method X. Given these facts, claim 1 likely satisfies the definiteness requirement.