Allen (elbow) isn't participating in practice Thursday, Chris Brown of the Bills' official site reports.
The Bills already ruled Allen out for their Week 8 game against the Patriots three days ago, so it's not expected he'll practice Thursday through Saturday while he nurses a sprained throwing elbow. Derek Anderson will earn a second straight start Monday in Allen's stead, despite an ugly showing in his team debut in the 37-5 loss to Indianapolis in Week 7.