Jamie Roberts scored on his Harlequins debut as Calvisano shipped nine tries in European Challenge Cup defeat at The Stoop.
The Wales centre was joined on the scoresheet by Marland Yarde, Kyle Sinckler, Jack Clifford, Ross Chisholm, Charlie Walker, Ben Botica, Tim Swiel and Karl Dickson. Botica also added 14 points with the boot.
Marco Susio scored Calvisano's only try, while Florin Vlaicu added the conversion that briefly levelled the scores.
Elsewhere, Newport Gwent Dragons stunned Pau as they claimed a bonus-point 34-17 victory in France.
The Dragons stormed into a 24-0 half-time lead thanks to tries from Cory Hill, Ashton Hewitt and Jason Tovey.
Remarkably, Carl Meyer's try eight minutes after the break gave the visitors a bonus point and ensured they led by 31 points.
Pau then put together something of a fight back as Paddy Butler, Mosese Ratuvou and Watisoni Votu breached the Welsh team's defence, but the Dragons weren't to be denied a famous win.
Newport now lead Sale by two points at the top of Pool Two after the Aviva Premiership side scored two tries in the last 10 minutes to secure a 31-10 home win over Castres.
Johnnie Beattie had narrowed the deficit to just six points as he scored Castres' only try but Neil Briggs and Johnny Leota both touched down to add to Viliami Fihaki's early score and wrap up victory.
Joe Ford, meanwhile, scored 11 points from the kicking tee while Danny Cipriani converted Leota's try and added a late penalty.
Brive enhanced their chances of making the knockout rounds with a 33-3 defeat of Russian side Enisei-STM.
The hosts ran in five tries in all to secure a bonus point and draw within two points of Connacht, who play Newcastle on Sunday.
In Italy, former All Black Mils Muliaina scored as Zebre won for the second time in this year's tournament, beating La Rochelle.
Muliaina struck with five minutes remaining, putting the seal on a 25-5 victory.