Cardinal Francis George has asked for continued prayers after being dropped from a cancer drug's clinical trial, which was determined to be ineffective for him.

"He is at peace, but he counts on everyone's prayers that he might be of service to the Lord and His Church in the time left to him," the Archdiocese of Chicago said Dec. 31.

"Cardinal George would like to thank all those who have been praying for him, and asks them to continue to do so. You and those you love are remembered in his prayers as well."

The 77-year-old cardinal and archbishop emeritus of Chicago had been taking part in a clinical trial conducted by University of Chicago Medicine, while also being cared for by Loyola University Hospital.

The drug, from the pharmaceutical company Genentech, is designed with the intention of helping the human body's immune system recognize and attack cancerous cells, the Chicago Sun-Times reports. Tests indicated that the drug has not been effective for the cardinal.

The archdiocese said the physicians and others overseeing the treatment of the cardinal have assured him that the information gathered in the clinical trial will help benefit others.

Cardinal George will meet with his doctors to discuss how to address his cancer's side effects. His cancer at present has not spread to any vital organs.

The cardinal was first diagnosed with bladder cancer in 2006. He then underwent a five-hour operation at age 69 to remove his bladder, prostate gland and sections of his ureters, the tubes which connect the kidneys to the bladder.

In August 2012, doctors discovered that cancerous cells had returned to his kidney and to a nodule in his liver.

Last year, the cardinal said that the cancer "will most probably eventually be the cause of my death."

Cardinal George headed the Archdiocese of Chicago from 1997 to 2014, when he was succeeded by Archbishop Blase Cupich. The cardinal was the first Chicago native to become the city's archbishop.