Holding: A claimed solution to a problem that is not known in the prior art is not automatically non-obvious. Motivation analysis for obviousness is not limited by the specific problem that is identified by the inventors.
ImmunoGen is the applicant for US Patent Application No. 14/509,809, which is directed to a dosing regimen for administering a patented antibody drug conjugate (ADC), called IMGN853, that may be used to treat ovarian and peritoneal cancers. Despite showing usefulness for cancer treatment, IMGN853 may cause ocular toxicity in humans leading to keratitis and blurred vision. The ‘809 Application attempts to develop an effective dosing regiment of IMGN853 that reduces the change of adverse side effects.
Claim 1 of the ‘809 Application recites a method for treating ovarian cancer or cancer of the peritoneum that comprises administering an immunoconjugate to the patient that binds to FOLR1 polypeptide. The immunoconjugate is “administered at a dose of 6 milligrams (mg) per kilogram (kg) of adjusted ideal body weight (AIBW) of the patient.” Using IMGN853 to treat ovarian or peritoneum cancer was already known at the time of filing, so patentability depends on this dosing limitation.
The ‘809 Application was rejected by the patent examiner and this rejection was affirmed by the PTAB. ImmunoGen brought suit in the Eastern District of Virginia seeking a judgment pursuant to 35 U.S.C. § 145, declaring that ImmunoGen was entitled to a patent for the claimed invention. The district court initially entered summary judgment of unpatentability finding that the term “AIBW” was indefinite; the dosing limitation was obvious in view of the prior art; and the claims are unpatentable for obviousness-type double patenting. The Federal Circuit vacated the summary judgment decision and remanded to the district court. In a three-day bench trial, the district court, once again, found the claims to be indefinite for failing to define AIBW and found the claims to be obvious in view of the prior art. ImmunoGen appealed this decision.
The Federal Circuit only considered the issue of obviousness, upholding the district court’s ruling that the ‘809 Application was obvious in view of the prior art. ImmunoGen argued that the district court erred in finding a motivation to combine the cited prior art because at the time the ‘809 Application was filed, it was unknown that IMGN853 may cause ocular toxicity in humans. However, the Federal Circuit declined to create a blanket rule that when a particular problem was not known in the art, then the claimed solution must be non-obvious. Neither the particular motivation of the patentee or the purpose of the patentee is controlling when determining obviousness. Instead, the objective reach of the claim should be considered. Motivation analysis to determine obviousness is not limited by the problem or need recognized by the inventor.
In this case, although IMGN853 was not specifically known to cause ocular toxicity at the priority date of the ‘809 Application, it was known that immunoconjugates that contain the maytansinoid DM4 could potentially cause ocular toxicity. Since IMGN853 includes DM4, the Federal Circuit found that there was no clear error in the district court’s finding that a person of ordinary skill in the art would have understood ocular toxicity as a potential risk of the administration of IMGN853.
ImmunoGen also argued that the district court erred by finding that a person of ordinary skill in the art would have tried AIBW dosing for IMGN853 to try to reduce the risk of ocular toxicity. It was already known that modifying dosing could reduce toxicity for other drugs associated with DM4, and AIBW was a known dosing methodology for cancer drugs. The Federal Circuit agreed with the district court that although AIBW had never been used particularly for administering ADCs, based on the prior art, it would have been obvious for a person of ordinary skill in the art to try this dosing method for IMGN853.
The Federal Circuit also affirmed the district court’s finding that the claimed dose of 6 mg/kg AIBW was obvious in view of the prior art. One of ImmunoGen’s prior patents disclosed dosing IMGN853 at about 6 mg/kg of total body weight rather than AIBW. Given that AIBW dosing was already known in the prior art, a person of ordinary skill in the art would likely start testing AIBW dosing around 6mg/kg. Additionally, in certain situations where the patient weighs the ideal body weight, the AIBW would be equal to their total body weight. Further, obviousness did not depend on a person of ordinary skill in the art having a reasonable expectation of success in eliminating ocular toxicity with the 6 mg/kg AIBW dosing. Instead, the district court only needed to show a reasonable expectation of success in treating ovarian and peritoneal cancers. Analysis of a reasonable expectation of success must be tied to the scope of the claimed invention, and none of the claims of the ‘809 Application discussed ocular toxicity.
Federal Circuit Precedential 
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