Moses Odubajo netted Orient's opener in Tuesday night's clash at Brisbane Road after keeper Chris Day saved from Chris Dagnall, who went on to score the second goal in the 23rd minute after David Mooney dispossessed defender Luke Jones.
Orient move second but are level on points with third-placed Wolves, who have two games in hand.
Fourth-placed Preston were held to a goalless draw away to MK Dons.
MK's Daniel Powell had the two best chances, the second of which saw Jack King brilliantly head his effort off the goal-line.
Carl McHugh's looping header in the last minute earned Bradford a 1-0 home win over Port Vale.
It was City's first win in 14 games and lifted them to 11th in the table.
Carlisle came from behind to beat Coventry 2-1 at Sixfields.
Franck Moussa gave Coventry a half-time lead but Liam Noble equalised (55) and Sam Byrne slotted home a 70th-minute winner from Lee Miller's through-ball.
The match between Crawley and Tranmere was postponed, the latest in a string of postponements for Crawley who now have up to seven games in hand on the teams around them in the table.