Harper is currently filming The Town That Came A-Courtin, a TV movie for the UP cable channel in Canada. Based on the novel by Ronda Rich, the film also stars Lauren Holly and Cameron Bancroft. Harper will play the owner of a bed and breakfast.
In January, Harper, 73, was diagnosed with leptomeningeal carcinomatosis, a rare condition that occurs when cancer cells spread into the fluid-filled membrane surrounding the brain.
"When I learned that the remarkable Valerie Harper was interested in working, I was so excited, because that meant she was doing well," UP Programming Chief Barbara Fisher said in a statement. "We are thrilled to have this iconic talent in our film and awed by her determination to live each day to the fullest. She is truly an inspiration."
Harper became famous when she landed the sidekick role of Rhoda Morgenstern on the CBS comedy The Mary Tyler Moore Show. She then starred in her own spin-off Rhoda. She won four Emmys and a Golden Globe for the role. In 2009, Harper was diagnosed with lung cancer, which she wrote about in her recent memoir I, Rhoda.