Drugs that free the body’s immune system to fight cancer have shown strong preliminary results in treating Hodgkin’s lymphoma, shrinking tumors in well over half of patients who had exhausted many other treatment options, researchers reported on Saturday.

The drugs have already generated great excitement because of their strong early results on various so-called solid tumors, particularly melanoma but also lung cancer, kidney cancer and some others. The results announced on Saturday represent the strongest evidence to date that the medicines, known as PD-1 inhibitors, also have promise for at least some of the so-called liquid tumors of the blood and bone marrow.

In a small study, the drug nivolumab, from Bristol-Myers Squibb, significantly shrank tumors in 20 of 23 patients, or 87 percent, with Hodgkin’s lymphoma. Four of the 23 patients, or 17 percent, had a complete response, meaning the total or near total disappearance of tumors.

The Merck drug pembrolizumab shrank tumors in 66 percent of 29 patients with Hodgkin’s, with 21 percent having a complete response.