In cases that reached final written decisions or were substantively denied institution, about 38% of claims that were originally challenged in PGR petitions were cancelled or found unpatentable. This statistic accounts for challenged claims which were denied institution for substantive reasons, as opposed to procedural reasons (e.g., time-barred). The analysis includes decisions not to institute through 2016, and final decisions through 2017, in order to account for the fact that final decisions typically issue about one year after the institution decisions. Unlike IPR and CBM proceedings, PGR proceedings can only be initiated for patents having a claim with an effective filing date that is on or after March 16, 2013, and can be filed on any ground (i.e., 101, 102, 103, or 112). The sample size available as of December 2017 was small (339 challenged claims). Consequently, it may be too soon to draw conclusions.