Pfizer says its experimental drug for deadly condition that causes appetite and weight loss in cancer patients shows positive trial results

Pfizer's experimental drug for a common, life-threatening condition that causes cancer patients to lose their appetite and weight showed positive results in a midstage trial, the drugmaker said Saturday. 

Patients with the condition, called cancer cachexia, who took Pfizer's treatment saw improvements in body weight, muscle mass, quality of life and physical function, according to the drugmaker. The results could pave the way for the drug, a monoclonal antibody called ponsegromab, to become the first treatment approved in the U.S. specifically for cancer cachexia. 

The condition affects about 9 million people worldwide, and 80% of cancer patients suffering from it are expected to die within one year of diagnosis, according to the company.

Patients with cancer cachexia don't eat enough food to meet their body's energy needs, causing significant fat and muscle loss and leaving them weak, fatigued and, in some cases, unable to perform daily activities. Cancer cachexia is currently defined as a loss of 5% or more body weight over the past six months in cancer patients, along with symptoms such as fatigue, according to the National Cancer Institute.

The symptoms of the condition can make cancer treatments less effective and contribute to lower survival rates, Pfizer said. 

"We would see ponsegromab fitting into the treatment of cancer patients, really addressing that unmet need in cachexia, and through that, improving their wellness, their ability to care for themselves, and we would also hope their ability to tolerate more treatment," Charlotte Allerton, Pfizer's head of discovery and early development, told CNBC in an interview. 

Pfizer has not disclosed the estimated revenue opportunity of the drug, which could potentially be