SAN FRANCISCO — Melky Cabrera was suspended 50 games Wednesday following a positive test for testosterone, putting an abrupt end to what had been an MVP-caliber regular season and throwing the San Francisco Giants’ playoff hopes into doubt.

Cabrera leads the National League with 159 hits, and is second in batting average behind Pittsburgh’s Andrew McCutchen. Cabrera’s penalty was the first for a high-profile player since last year’s NL MVP, Ryan Braun, had his suspension overturned by an arbitrator last winter.

“My positive test was the result of my use of a substance I should not have used,” Cabrera said in a statement released by the union. “I accept my suspension under the Joint Drug Program and I will try to move on with my life. I am deeply sorry for my mistake and I apologize to my teammates, to the San Francisco Giants organization and to the fans for letting them down.”

The suspension would extend into the playoffs if the Giants advance.

Cabrera is batting .346 with 11 home runs and 60 RBIs in his first season with San Francisco and is five hits shy of 1,000 in his big league career. Flashing bright orange spikes, he singled and hit a two-run homer last month in the National League’s 8-0 win in the All-Star game, earning MVP honors for the game and securing homefield advantage for the World Series.

“It’s disappointing. Obviously, Melky means a lot to all of us, was part of our championship and provided some really good moments here,” Yankees manager Joe Girardi said. “It’s something that everyone has to deal with and it’s something baseball is trying to stay away from and it happened.”

Cabrera could still win the NL batting title. He has 501 plate appearances, one less than the minimum required to win a batting championship for a player on a team playing 162 games. However, under 10.22(a) of the Official Baseball Rules, he would win the batting title if an extra hitless at-bat is added to his average and it remains higher than that of any other qualifying player.

He will miss the final 45 games of the regular season and serve the remainder of the suspension at the start of next season or during the postseason, depending on whether the Giants make the playoffs and how far they advance. If the Giants wanted him to become active in the middle of a playoff series, they would have to play a man short from the start of the series until the suspension ends because rosters can’t be altered mid-series.

“We were extremely disappointed,” the Giants said in a statement. “We fully support Major League Baseball’s policy and its efforts to eliminate performance enhancing drugs from our game.”

Cabrera became the second Giants player to receive a drug suspension this season. Reliever Guillermo Mota was penalized for 100 games in May, becoming just the third major league player disciplined twice for positive drug tests. Mota is eligible to return Aug. 28, barring rainouts, and began a minor league rehabilitation assignment Tuesday with the Giants’ rookie team in Arizona.

It was not immediately known whether Cabrera’s positive test occurred before the All-Star game. The union initially filed a grievance, which would have caused the case to go before an arbitrator, but then dropped it, a person familiar with the process said. The person spoke on condition of anonymity because that detail was not announced.

Cabrera told CSN Bay Area on July 27 that he had been tested for performance-enhancing drugs the previous week, though it’s unknown whether the test he referenced resulted in the positive test.