Jennifer Maas TV Business Writer What started as a singing competition special featuring Wiz Khalifa and Bebe Rexha that aired during NBA All-Star Weekend on TNT is now being shopped as a full-format series, Variety has learned. From “The Biggest Loser” and “World of Dance” executive producer Alex Katz, co-founder of Anagram Studios, the special was titled “The Sum” and though it prominently featured Wiz Khalifa and Rexha, they weren’t the competitors. Their fans, singing along to their hit songs, were the real players. Per “The Sum’s” description, “‘The Sum’ is an original concept based on the best part of any concert — fans singing along with the artists, also known as ‘the common chorus effect.’ In ‘The Sum,’ fans share the spotlight with their favorite music stars by performing a song together.”