Victory on the road at Catalans Dragons sees London Broncos join three other teams on 18 points at the foot of Super League.
Ratu Naulago scored twice as Hull FC eased past Super League strugglers Wakefield Trinity on Sunday.
Salford Red Devils cruised against London Broncos, while Hull KR beat Castleford Tigers in dramatic circumstances.
St Helens have only lost three games all year in Super League, but two of those defeats have come at London Broncos.
Having seen health problems halt a boxing career, Manu Vatuvei has now also called time on his rugby league playing days.
Super League table-toppers St Helens moved 10 points clear after a 32-10 win over Wigan Warriors, while Salford surprised Warrington.
Darnell McIntosh played a starring role as Huddersfield Giants ended a four-game losing streak with victory at Salford Red Devils.
Warrington Wolves looked set to close the gap on Super League leaders St Helens, but Jonny Lomax inspired his side to yet another victory.
Leeds Rhinos have brought in Robert Lui and Shaun Lunt, with Tui Lolohea and Matt Parcell leaving Headingley.
New Zealand Warriors great Manu Vatuvei has not played since 2017 and revealed on Wednesday he has a cyst in his brain.