The series will no longer count two years' worth of races.
World Marathon Majors champ Rita Jeptoo is under fire after failing a test for EPO in September.
The Kenyan was tested in late September before defending her Chicago Marathon title.
Toni Reavis explains why the Boston Marathon is such a big deal.
There is $500,000 World Marathon Majors title is on the line.
The running community applauds these efforts.
It’s much easier to talk about anti-doping than to actually do it, and so far, it’s not clear what the plan is.
Announcement comes on same day that three Kenyan marathoners get banned for doping.
It's now the sixth event in the series.