The court affirmed the district court's decision that IMMUNOGEN's patent application for a specific dosing regimen of its cancer drug, IMGN853, was unpatentable due to obviousness. The central issue was whether using an adjusted ideal body weight (AIBW) based dosage of 6 mg/kg for the drug would have been obvious to someone skilled in the art at the time of the invention, considering existing knowledge about the drug and dosing methods, even if the specific ocular toxicity problem the inventors aimed to solve was not yet publicly known for this drug. The court found that prior art disclosed similar dosing and recognized the potential for toxicity, making the claimed dosing regimen obvious.