Coach Kieran Crowley has selected a 26-man squad for the series.
Canada, ranked 13th in the world, meets the 17th-ranked U.S. Eagles on June 9 in Kingston, Ont., No. 11 Italy on June 15 in Toronto and No. 15 Georgia on June 23 in Burnaby, B.C.
Veterans missing include World Cup captain Pat Riordan and Ryan Smith, both of whom have retired.
"With retirement and unavailability of some players, we are looking at testing some of our younger players in these internationals to get a measure of where they are with their development," Crowley said in a statement. "We don't get too many opportunities to play quality teams like this."
The roster features six professional players including Sinclair, who is currently playing Super Rugby for the Stormers in South Africa, and van der Merwe (Glasgow Warriors).
Newcomers include Brett Beukeboom, Tyler Ardron, and Jeff Hassler.
"These matches will be a great test for our group, as it is the first time since the Rugby World Cup the team has been on the field," said Gareth Rees, Rugby Canada's national program manager. "Games such as these, are a great measuring stick for Canada to find out how we rank against similarly ranked teams as well as a fully professional Six Nations competitor (Italy)."
Ryan Hamilton, B.C, West Vancouver; Mike Pletch, Ontario Blues, Lucan, Ont; Hubert Buydens, Prairie Wolf Pack, Saskatoon; Doug Woolridge, Ontario Blues, Lindsay, Ont,; Tom Dolezal, Ontario Blues, London, Ont.; Andrew Tiedemann, Prairie Wolf Pack, St. Albert, Alta.; John Phelan, The Rock, Montreal; Tyler Hotson, Plymouth Albion, Vancouver; Brett Beukeboom, Ontario Blues, Lindsay, Ont.; Jebb Sinclair, Stormers, Charters Settlement, N.B.; Chauncey O'Toole, Atlantic Rock, Belleisle, N.B.; Nanyak Dala, Prairie Wolf Pack, Saskatoon; Aaron Carpenter, B.C.. Brantford, Ont,; Tyler Ardron, Ontario Blues, Lakefield Ont,; Sean White, unattached, Victoria; Ed Fairhurst, B.C., Regina; Connor Braid, B.C., Victoria; Matt Evans, Cornish Pirates, Duncan, B.C.; DTH van der Merwe, Glasgow Warriors, Victoria; Mike Scholz, Ontario Blues, Oakville, Ont.; Connor Trainor, B.C.; Vancouver; Sean Duke, B.C., Vancouver; Jeff Hassler, Prairie Wolfpack, Okotoks, Alta.; Ciaran Hearn, The Rock, Conception Bay, N.L.; Phil Mackenzie, Esher RFC, Oakville, Ont.; James Pritchard, Bedford Blues, Parkes, Australia.
June 9 -- Canada vs. U.S., Kingston, Ont.
June 15 -- Canada vs. Italy, Toronto.
June 23 -- Canada vs. Georgia, Burnaby, B.C.