Reply by Authors. Issue 4 (23rd October 2021) - Agarwal, Neeraj; McQuarrie, Kelly; Bjartell, Anders; Chowdhury, Simon; Pereira de Santana Gomes, Andrea J.; Chung, Byung Ha; Özgüroğlu, Mustafa; Juárez Soto, Álvaro; Merseburger, Axel S.; Uemura, Hirotsugu; Ye, Dingwei; Given, Robert; et al.