"Jeopardy!" host Alex Trebek revealed that he is undergoing another round of chemotherapy after a setback in his battle with pancreatic cancer. He first revealed the news Tuesday morning in an interview with ABC's "Good Morning America." 

"Jeopardy!" later published a video with an update from Trebek

"One of the things I have learned in the past six months is that the course of pancreatic cancer treatment is not a straightforward affair. There are always curves and unexpected events," Trebek described. He went on to tell fans how earlier this Summer they thought he was done with chemo because he was making such good progress. 

"That was a bit premature and certainly over optimistic," Trebek explained. After issues with immunotherapy, doctors revisited his situation and advised him to do more chemotherapy. 

The longtime game show host announced in March that he had been diagnosed with stage 4 pancreatic cancer. "I'm going to fight this, and I'm going to keep working," Trebek said in his first video message to fans. "Keep the faith and we'll win. We'll get it done. "

Just months later in August, Trebek announced he was "on the mend" and done with chemotherapy.

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"I've gone through a lot of chemotherapy and thankfully that is now over. I'm on the mend and that's all I can hope for right now," Trebek revealed during a video previewing season 36 of the longtime game show. 

Now, his doctors have decided to have him undergo another round of chemotherapy after he lost a large amount of weight and his numbers increased dramatically.

"I was doing so well," he told "Good Morning America." "And my numbers went down to the equivalent of a normal human being who does not have pancreatic cancer. So we were all very optimistic. And they said, 'Good, we're gonna stop chemo, we'll start you on immunotherapy,'" 

But, then Trebek lost 12 pounds in a week. "My numbers went sky high, much higher than they were when I was first diagnosed. So, the doctors have decided that I have to undergo chemo again and that's what I'm doing," he said.

Early on in his cancer treatment, Trebek discussed his battle with depression that started when he was first diagnosed. The host recalled how he was "writhing in pain" between tapings during the end of the last season. 

Since his diagnosis, Trebek has received an outpouring of support from fans, friends and family.

"They have been an inspiration to me. That's really what it's all about," he said.