The American Association of Physicists in Medicine (AAPM), along with the SPIE (the international society for optics and photonics) and the National Cancer Institute (NCI), will conduct a part 2 “Grand Challenge” on the development of quantitative multi-parametric magnetic resonance imaging (MRI) biomarkers for the determination of Gleason Grade Group in prostate cancer. As part of the 2017 AAPM Annual Meeting, the PROSTATEx-2 Challenge will provide a unique opportunity for participants to compare their algorithms with those of others from academia, industry, and government in a structured, direct way using the same data sets.  To learn more about the challenge please visit http://www.aapm.org/GrandChallenge/PROSTATEx-2/default.asp. To register for the challenge visit http://spiechallenges.cloudapp.net/. Data from TCIA that was used by this challenge is available at SPIE-AAPM-NCI PROSTATEx Challenges.