St. Louis Cardinals pitcher Miles Mikolas will be reevaluated in four-to-six weeks after receiving a stem cell injection due to a small calcification found within the flexor tendon of his throwing arm.

Mikolas, 32, left Sunday’s game against the Chicago Cubs after four innings. It was his first start since 2019 after undergoing surgery to repair the tendon while missing the early portion of this season with a sore shoulder.

The Cardinals indicated he’ll be reevaluated in four-to-six weeks and are hopeful he can return this season.

Mikolas signed a four-year, $68 million deal with St. Louis before the 2019 season. He went 18-4 with a 2.83 ERA in 2018 after returning from playing in Japan the previous three years.

Since his new contract took effect, Mikolas has made just the one start, last Sunday.