今日上午A股跌幅最大企业，凯因科技主动撤回乙肝药上市申请

Group 1 - The core point of the article is that Kaiyin Technology (688687.SH) has voluntarily withdrawn its application for the listing of its hepatitis B drug, leading to a significant drop in its stock price by 11.78% on January 21, making it the largest decline in the A-share market that morning [1] - The company received a termination notice from the National Medical Products Administration, which approved the withdrawal of its drug registration application for Pegylated Interferon α-2 Injection (new hepatitis B indication) [1] - Pegylated Interferon α-2 Injection is a novel long-acting interferon developed by Kaiyin Technology, which was approved in 2018 for the treatment of adult chronic hepatitis C [1]