We discussed the effect that disclosure of prior art genera and species would have on the novelty of a later claimed genera and species containing very similar subject matter. For example, we found that in certain cases, a prior art species could anticipate a later claimed genus. We also learned that an attempt to claim a91See, for example, Ruiz v. A.B. Chance Co., 234 F.3d 654, 668 (CAFC 2000) citing In re Hedges, 783
F.2d 1038, 1041 (CAFC 1986), “[P]roceeding contrary to the accepted wisdom. . . is ‘strong evidence of un obviousness”.
FIGURE : Venn diagram of relationship between prior art genus that encompasses alater claimed genus and species.
species that fell within an earlier disclosed genus might be anticipated, if the earlier claimed genus was small enough so that each and every member of the earlier claimed genus could be at once envisaged. However important these two situations are to patentability, they do not account for many possible situations that can occur when the prior art discloses a genus and an applicant is later attempting to claim aspecies or genus that somehow relates to that prior art genus (meaning the claim iseither enclosed, overlaps or abuts the earlier claimed genus). Given the importance of genera in the chemical arts, evidenced especially by the common adoption of Markush descriptions, it will be worthwhile to delve further into understanding these relationships in view of how they affect obviousness determinations.
To start, a situation that very often occurs in the chemical arts can be depicted symbolically (Figure above) in which a prior art genus is represented by the large circle. Most often, the prior art genus will be part of a patent or patent application publication but does not necessarily have to be; it might also be part of a disclosure in the general chemical literature. The prior art genus may or may not contain actual examples within its scope that have been prepared or otherwise singly identified in the prior art disclosure. The presence or absence of actual examples within the genus will often be an important aspect of the obviousness determination that we undertake,as is the size of the genus together, of course, with their structural relationship and related teachings with the genus and compounds we wish to claim. To “put some meaton the bones,” let’s take a look at the ways that a prior art genus may relate to our attempt to later claima species or genus that is somehow related to the prior art genus.
In this first scenario, a chemist has found that either a single compound or set of compounds that he has made falls entirely within the scope of a genus disclosed in the prior art. The applicant wishes to claim his own genus of compounds that he has also populated with a few working examples. In his patent application, he would most likely try to claim both the genus and the individual examples separately. The instinctive reaction of the practicing chemist in such a situation is to write off the pursuit of compounds that fall within a prior art genus. In this regard, it is important to appreciate that “The fact that a claimed species or subgenus is encompassed by a priorart genus is not sufficient by itself to establish a prima facie case of obviousness.”
As we proceed with the obviousness inquiry, we first focus on the prior art disclosure itself. According to the USPTO, patent examiners should take into account the following factors of the prior art:
The structure of the disclosed prior art genus and that of any expressly described genus, subgenus, or species within the disclosed genus.
Any physical or chemical properties and utilities disclosed for the genus as well as any suggested limitations on the usefulness of the genus and any problems alleged to be addressed by the genus.
The predictability of the technology.
The number of species encompassed by the genus taking into consideration all of the variables possible.
First, we will want to note the structure of the disclosed prior art genus, including any expressly described genus, subgenus, or species within the disclosed genus. If the genus is like the broader map, then any subgenus and/or species contained therein are like streets and house locations. As we determine the prior art effect that this genus map might have on any later attempt to claim compounds or subgenera falling within its purview, we need to closely consider the extent to which the map is already filled in and, accordingly, whether the details of the genus and its contents are sufficient to render the later claimed compounds obvious in view of the collective teachings of the prior art.
Next, we will need to consider any physical or chemical properties and utilities disclosed for the prior art genus, as well as any suggested limitations on the usefulness of the genus, and any problems alleged to be addressed by the genus. This is important, for example, because when we consider what motivates one of ordinary skill in the art, we cannot ignore the presence or absence of a disclosed utility. From In re Dillon we learned that the particular utility disclosed in the prior art was not important, only that a utility was disclosed such that one of ordinary skill in the art would have been motivated to prepare the later claimed compounds that are in question. However,there still must be a disclosed utility sufficient to motivate one to modify the prior art compounds or genus in such a way as to render a later claimed compound or genus obvious. Thus, for example, if a genus of compounds was disclosed together with information suggesting that genus of compounds was inactive or not useful, then it is highly unlikely that one of ordinary skill in the art would be motivated to make additional analogs or compounds within such a genus given its alleged lack of utility.
The third point requires that we consider the predictability of the art or technology in question. As we have previously discussed, where one is ascertaining the relative obviousness of a compound or genus of compounds relative to a prior art disclosure of a genus of compounds and related compounds, the obviousness or not of making changes to the prior art genus to arrive at the later claimed invention must take into account how predictable the result is likely to be—less predictability equals less likelihood of finding the motivation to make specific changes. Different areas of chemistry might have different relative degrees of predictability, depending on the narrower question of what is being looked into.
The last point concerns the size of the prior art genus. All things being equal, a large prior art genus is less instructive then a small prior art genus. An allegation that a very large prior art genus makes later claimed species or subgenus falling within that disclosure obvious is tantamount to saying the proverbial haystack makes every hidden needle obvious.
Once the prior art disclosure has been properly characterized according to the four factors just discussed, the next step is to compare the species or subgenus that the applicant wishes to any subgenus or species disclosed in the prior art according to the following process:
Compare the claimed species or subgenus to the prior art genus.
Identify the closest prior art species or subgenus to the claimed species or subgenus.
Make explicit findings of the similarities and differences in terms of structure, properties, and utility between the prior art genus, subgenus, species, and the claimed species or genus.
Then, looking at all the evidence before us, we will need to decide whether the priorart disclosure would have motivated one to make the later claimed invention and whether she would have a “reasonable chance of success” in doing so.
Of course, should this analysis result in a sufficient finding to make the later claimed species or genus obvious, then the applicant will have the opportunity to establish secondary evidence of non obviousness, such as unexpected properties, as we have already discussed.
To reduce these theoretical considerations to an example, let’s take a look at a hypothetical situation in which the prior art discloses a genus together with some compounds falling within the genus. In view of the prior art disclosure, we’ll do an analysis using the principles we have just discussed.
A chemist working for a small pharmaceutical company has discovered that a class of compounds she created up regulates insulin secretion in animal models of hypoinsulinemia and may be useful for the treatment of diabetes. The compounds appear to work by a different mechanism then currently used therapies and appear to be safe, having little or no apparent toxicity in various pre clinical toxicological models. The chemist creates a Markush representation of molecules that she believes will work for the desired utility and for which she believes she has provided sufficienten ablement for their preparation and use. She has also singled out one particularly good compound that may become a development candidate, a compound that she would like to claim separately from the genus. However, in her prior art search, she has become aware of a document that she is worried will impact the patentability of her invention. The prior art disclosure is a published patent application with a claim to a genus of compounds as well as two compounds that fall within the genus. It discloses that the compounds have a number of different utilities, including use as potential treatments for various maladies, but diabetes is not specifically mentioned.
The relevant structures are shown in Figure above.
The beginning of our analysis requires that we first appraise the prior art disclosure(“scope and content of the prior art”). The prior art describes a genus of compounds
FIGURE :Prior art disclosure and proposed genus and species.
with a bicyclic or tricyclic core, wherein when that core is tricyclic, the optional thirdring is further optionally substituted with numerous possible groups including C1-3alkyl. Appended to the core, attached via a carbon or nitrogen atom (the X group)of the core structure is a linker comprising an optional aromatic group (it is optional since Y can also be a bond) and a second aromatic or letterform group, where that second aromatic or heteroaromatic group is substituted with a further optionally substituted amino group.
Next, we move to step 2 of the evaluation of the prior art. There is utility for the prior art genus and compounds; they are reported to have activity as medicaments although a specific teaching regarding diabetes is not present. From In re Dillon,we know that the disclosure of any utility is enough to motivate one to modify the prior art structures. Had there been no disclosed utility for the compounds or if the disclosure had revealed an undesired activity or aspect of the compounds, then it is possible that a motivation to modify the prior art compounds would not have been present, but this is not the case here.
In regard to the predictability of the technology (step 3 of prior art analysis) we can probably make some generalizations but are limited by the facts as to how far we might go. In particular, we know that the chemical sciences are generally not very predictable; medicinal chemistry is particularly problematic on that score. One is trying to understand not only the attributes of one’s own compounds or genus but also the interaction that those compounds will have in complex biological systems where the fundamental nature of the drug target(s) interaction is generally not well understood. It has been shown time and time again that even very small changes in a drug’s structure can have profound effects on a molecule’s biological profile .Since an unpredictable technology is less likely to lead to obvious solutions based on prior art structures, we recognize that this factor cuts against a finding of obviousness based on those prior art structures.
The last step in the appraisal of the prior art genus is to examine the size of the genus, meaning the number of hypothetical members contained within the genus. Alarge genus dilutes the effect of whatever structures it is teaching because there are so many possibilities to consider.99 Since the number of possible structural embodiments of a genus is the product of the number of possible variations at each position, the present prior art genus is tremendously large, containing a very large number (at least many millions) of hypothetical compounds.
Having completed the prior art analysis, we next must appraise the compounds and genus that our chemist wishes to claim. Let’s first verify that our chemist’s proposed genus (and a fortiori the species falling within it) fall within the scope of the priorart genus. Starting with the left-hand side of the prior art genus first, we will set variables A and B to CH. Next, we note that variables C and D may be connected viaa linker such that the result can generate a five-member heteroaryl group, including one containing a single nitrogen in the backbone. Further, the five-member heteroaryl group is optionally substituted with from one to three groups, including a C1-3 alkyl.
The variables on the left-hand side of the prior art genus allow for a selection that would cover the left-hand side of the claimed species and subgenus. Moving to the right-hand side, the variable X can be set to a carbon atom, thus matching the proposed genus and species atom at that position. Y can be an aromatic ring or abond. When Y is a bond, the meaning is that Z and X will be directly bonded to each other. By selecting Y as a bond, the Z group can then be selected as a six-member aromatic (benzene ring), and R1 and R2 can be hydrogen or C1-3 alkyl. Through the process of picking and choosing the appropriate groups from the prior art Markushgenus, we are able to confirm that it does circumscribe the subgenus and species that our chemist wishes to patent, and so we understand the relationship between the compounds and the genus the chemist wishes to claim and the prior art genus.
Now that we’ve confirmed the relationship between the prior art disclosure and the chemist’s genus and species (matching that depicted in Figure 8.22) we can begin to make the critical point-by-point analysis to see if the prior art would render the claimed species and/or genus obvious.
Our first observation is that the prior art genus is very large, containing a very large number of hypothetical members. As we have already discussed, the larger the prior art genus (all things being equal), the less likely it is to suggest any particular embodiment falling within it. Second, the genus contains certain embodiments that are only optionally present and contains no additional instruction that would direct one to actually include such an embodiment. For example, the core structure that is specifically delineated in the prior art Markush is a bicyclic ring system that can be one of many possibilities, depending on whether the variable backbone members are selected as carbon or nitrogen. The ability to fuse a third ring on is only an optional embodiment, where that fused ring can be in one of three positions and where that fused ring can be chosen from potentially hundreds of different letterform systems. The Markush genus that is sought to be claimed requires a specificheteroaromatic ring (pyrrole) to be fused in a specific position, which together makeup the benzo[g]in dole ring system. In addition, we can see that the bicyclic core of the prior art Markush genus contains numerous optional nitrogen atoms at various positions. Thus what may at first look to be a single bicyclic core contains the possibility of dozens of different bicyclic ring systems, depending on the selection of A, B, C, and X. Further, there are additional optional substituents available to the prior art Markush that are not present in the proposed genus or species. For example,the prior art Markush allows for an additional aromatic linker Y to be present,whereas the proposed genus and species do not. Notice further that the aromatic and heteroaromatic choices in the linker (-Y-Z) piece of the prior art are defined onlygenerically, and in fact, each one of Y and Z must in turn be selected from a very large number of ring systems. Taken in sum, there are a very large number of possible ways that one of ordinary skill in the art could proceed from the prior art disclosure without ever finding their way to the later claimed genus. This means that the prior art genus, by itself , fails to render the later claimed genus obvious. How could it? Look at the prior art genus, now look at the proposed genus to be claimed.
Would the prior art genus motivate one to make the proposed genus or species? Of course not! What would have motivated, taught, or suggested one of ordinary skill in the art to make the proposed genus (and species) rather than any of the millions of other possibilities that the prior art genus might suggest? A synthetically skilled organic chemist could work many lifetimes randomly making analogs falling within the prior art genus and never even come close to making a compound falling within the later claimed genus.
We are not done yet however.We need to remember that the prior art is good for all that it teaches and thus we need to look at what else the prior art document provide sin the way of further direction. Of special interest, notice that not only does the priorart provide a genus of compounds having various asserted utilities but it also providesa couple of actual examples that fall within the genus scope. The question is whether these specifically disclosed prior art compounds direct us closer to our proposedgenusand compounds? First, we can see that both of the exemplified species are similar in structure to each other, containing tetrahydronaphthyridine core ring systems. Thusneither represents a benzo[g]indole as is required by the proposed genus and species.
In fact, neither prior art species even possesses a tricyclic core. Furthermore, the twoprior art examples contain the optional linker where Y is phenyl and such a group is not present on the proposed genus or species. So, would the specifically exemplified structures lead one closer to the later claimed Markush and species? The answer is almost certainly no, since if in fact these compounds are signposts, they are actually pointing away from the direction taken by the applicant’s claimed species and genus.
So, given the very large size of the genus, and the unpredictability of the art coupled with a lack of additional teaching that would motivate one to make the proposed genus or compound, the prior art disclosure in this hypothetical will not render the later claimed genus and species obvious.
We have just analyzed the situation in which a prior art genus, due to great breadth and insufficiency of any additional teaching, would not render obvious a later claimed narrow genus and compound falling within its scope. To clarify through comparison and distinction, let’s change the facts of the previous hypothetical scenario in a way that will help highlight the type of scenario that more readily avails itself to an allegation of obviousness. As we explain this alternate situation, we’ll keep closely in mind the factors that we discussed in our previous scenario, remaining vigilant
FIGURE : Narrower prior art genus and species.
to how they differ from the current scenario and why that makes a difference. In addition, to more approximately mimic what might happen in a real-world scenario,we will combine additional teachings from another prior art reference.
Let’s assume that reading the prior art further, our chemist notes an additional Markush genus is one of several preferred embodiments in the prior art reference and that a single compound D falling within the preferred embodiment is also disclosed(Figure above). Also, a quote from a second prior art reference has been included,which suggests the interchangeability of a thiophene for a phenyl group.
This preferred prior art Markush genus disclosure is much narrower than the
previous genus disclosure of Figure above. Many of the variable choices have been significantly narrowed or eliminated, resulting in a genus that creates a much tighter cage for the compounds and genus our chemist wishes to claim (thinking back to our original hypothetical Figure above the size of the outer circle representing the prior art genus has now been made much smaller). However, there is more. The priorart also teaches a specific example that contains a thiophene moiety directly bondedto a tetrahydrobenzo[g]indole (the same core as the proposed genus and species).From this, we can see that the claimed compound C in Figure above differs from priorart example D only in that the pendant amino-substituted thiophene group has been replaced by a pendant amino-substituted phenyl. Assuming utility was alleged or disclosed for compound D, a case of obviousness still requires that one have some reason (i.e., be motivated) to make the claimed compound or genus. The essential question in the instant case then boils down to whether the prior art would motivate,teach, or suggest one to substitute the thiophenyl group of the prior art with the phenylgroup of the claimed compound and genus; in other words, would it be obvious to substitute a phenyl group for the thiophene in the prior art? First, we can look to the express teaching of the genus itself. From the description of Z, it is apparent that a phenyl group is one of the four possible groups. So in addition to the teaching of a structurally very similar compound, the same reference also teaches a preferred subgenus where the thiophene is interchangeable with a phenyl group. Further yet,there is a second prior art reference that teaches the common interchangeability of athiophene group for a phenyl group. Since prior art reference 2 teaches that one of ordinary skill in the art would appreciate that a phenyl group and a thiophene share abioisosteric relationship and the prior art Markush provides a phenyl group as one of a limited number of choices for that position, one could make a very strong prima facie case that it would be obvious for one of ordinary skill in the art to prepare a phenylanalog of the compound D, which is the same structure as that desired to be claimed.The motivation is clear: the preparation of additional, biologically active compounds for use as medicines. Of course, the type of obviousness “proved” by the analysis of the prior art is prima facie only and still subject to the consideration of secondary evidence of non obviousness (Graham step 4). So it is likely that our chemist needs to find some secondary consideration, such as unusual results to differentiate her compound with a phenyl group from the prior art compound with a thiophene.
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