How Ex parte Chowdhury Can Help in Future Patent Examination
The PTAB’s informative decision in Ex parte Chowdhury provides applicants with a useful basis for responding to improper Markush grouping rejections, particularly in biotechnology method and combination claims. It emphasizes that the grouped alternatives must be assessed according to their role in the claimed invention.
In Chowdhury, the examiner rejected groups of microRNAs because their different nucleotide sequences allegedly lacked sufficient structural similarity. The Board reversed, finding that the microRNAs were interchangeable for their claimed purpose: serving as measurable biomarkers of radiation exposure. Differences in their individual biological activities did not defeat that shared role.
In future examination, applicants can use this reasoning to explain why structural differences among listed alternatives do not necessarily make a Markush group improper. A response should identify the members’ relevant similarities, connect those similarities to their common use, and cite specification support showing that the alternatives can achieve the same intended result within the claimed method or combination. This approach addresses the requirements of structural similarity and common use in the context of the invention.
The decision also offers a drafting lesson: applications should clearly explain why grouped alternatives belong together and how each performs the claimed role. Such disclosure may strengthen later responses to Markush objections. Any application of this reasoning to antibody claims remains case dependent, and establishing a proper grouping does not itself resolve separate enablement or written-description issues.