Well, you know how hope tends to fare in 100 Land: The series, which never got a formal title, is now thoroughly dead, per Deadline, before it even got a chance to get off the ground. The show in question would have taken place 97 years before the beginning of the original series, playing out the immediate aftermath of the nuclear apocalypse that forced humanity into the extreme conditions it’s laboring under when the flagship series begins.
The prequel show—which would have supposedly run jointly on The CW and HBO Max—was greenlit back in October 2019, shortly after the conclusion of The 100's sixth season. The show wasn’t ordered to series in May 2020 (which was a pretty, uh, eventful month in terms of efforts to keep TV production alive, anyway) but wasn’t canceled, either; CW president Mark Pedowitz went so far as to reassure fans in May of this year that the show was “not done in any way, shape or form.”
Well, an appropriate shape or form now appears to have been found, because the series is now apparently as dead as a love interest on, well, The 100. That comes after a more unofficial failure point last year, when The CW allowed its options on Iola Evans, Adain Bradley, and Leo Howard, who all appeared in the backdoor pilot for the series, to expire.
The prequel, like The 100 itself, was developed by Jason Rothenberg.