The Sweden international was not in his house in Northumberland, in northeast England, when the gang broke in through a glass door last April, Newcastle Crown Court was told.
The thieves had already stolen jewellery and clothes worth more than £1 million from a businesswoman and designer goods worth £100,000 from another woman in the previous days.
Three members of the same family, living in Italy, have admitted conspiracy to commit burglary, the court heard.
A fourth family member, Valentino Nikolov, 32, denies the charge.
Dan Cordey, prosecuting, said Isak left his home between 16:00 and 22:00 BST on April 4th, and he discovered the break-in when he returned.
The gang broke into his TV room and "inside an untidy search took place", Cordey said.
Cash between £5,000 and £10,000 was taken, along with jewellery worth about £68,000 and Isak's Audi car, which a member of the public later found abandoned, jurors were told.
CCTV images of the break-in were recorded.
"This was a professional group of travelling burglars," said Cordey.
"It contained one female and three men - all related. Two of those men and one female have admitted their part in pleading guilty."
Cordey said the fourth man was the defendant Valentino Nikolov.
The gang arrived in Britain via a ferry from Calais to Dover last March, using a motor-home as their base, the court heard.
Nikolov, of Birmingham, is representing himself at the trial and requires an Italian interpreter.
Jurors have been told his brother Giacomo Nikolov, 28, his sister Jela Jovanovic, 43, and her son Charlie Jovanovic, 23, who all live in Italy, have admitted conspiracy to commit burglary.
Isak has enjoyed a standout season for Newcastle, scoring 22 goals in all competitions for Eddie Howe's team, who face Liverpool in the League Cup final at Wembley on March 16th.