The Chairman then asked the FDA to explain the circumstances under which it would be "necessary for a biosimilar product to disclose in its labeling that it has not been found interchangeable with its reference product (or other products found biosimilar to the same reference product)." Id. (internal quotations omitted). The FDA responded on June 22, 2015, after AbbVie's submission of its initial citizen petition, and once again stated that "health care professionals should have product labeling that includes the essential scientific information necessary to make informed prescribing decisions for their patients." Id. (internal quotations omitted). However, the FDA told the HELP Committee that interchangeability information did not need to be included in biosimilar labeling because prescribers could obtain the omitted information in the Purple Book. Id. at 2-3. AbbVie argued that "[t]he proposition that The Purple Book could cure a material omission in the labeling for a biosimilar is indefensible." Id. at 3.