High-dose Vorinostat effective at treating relapsed lymphomas

Patients whose aggressive lymphomas have relapsed or failed to respond to the current front-line chemotherapy regimen now have an effective second line of attack against their disease. Reporting the results of a first-of-its-kind phase 1 clinical trial to test the effectiveness of a new class of drugs to augment standard chemotherapy, a team led by Hutchinson Center scientists found that giving patients high doses of Vorinostat (suberoylanilide hydroxamic acid) in combination with commonly used second-line drugs resulted in a 70 percent response rate, including several patients whose lymphoma cells disappeared entirely.

The results were published online Jan. 29 in the British Journal of Haematology. According to Dr. Ajay Gopal, a researcher in Fred Hutch’s Clinical Research Division and corresponding author of the paper, the findings potentially solve the dilemma of how to effectively treat patients when modern cancer drugs fail after the first try. And, he said, it sets the stage for using a new class of drugs called histone-deacetylase inhibitors—of which Vorinostat is one—to sensitize tumor cells to the cancer-killing effects of chemotherapy.

Better transplant outcome

Patients treated in the trial had several types of lymphoma; however, the best responses were seen in those who had Hodgkin and diffuse large B-cell lymphomas, two of the most aggressive types that typically require a stem cell transplant if they are not cured after the first line of treatment. Knocking back the cancer raises the likelihood for a successful transplant.

"The better the response, the better the outcome will be when patients proceed to a stem cell transplant designed to cure them of their disease," said the study’s first author, Dr. Elizabeth Budde, also in the Clinical Research Division.

The researchers noted that while the current front-line chemotherapy drugs are the most effective yet against lymphomas, patients who relapse after receiving them are less likely to achieve long-term, disease-free survival when current second-line or "salvage" therapies are applied. This is because the cancers develop resistance to the drugs or the tumor’s biology changes in some way to reduce their effectiveness.

Lymphomas are cancers that strike the lymphatic system, which is a key part of the immune system. Lymphomas are broadly classified as either Hodgkin or non-Hodgkin. Some lymphomas are highly curable; others require complex treatment.

How Vorinostat works

Preclinical studies at Fred Hutch and other research centers have found Vorinostat to be effective when used along with the standard chemotherapy combo, known by the acronym (R)ICE for rituximab, ifosphamide, carboplatin and etoposide. Vorinostat works by blocking signals to tumor-suppressor genes, which allows those genes to induce tumor cell death.

The phase 1 trial involved 27 patients at about a dozen sites in the Puget Sound Oncology Consortium. Some level of response was observed in 19 patients, including eight complete responses. Because many of the patients were destined for an autologous hematopoietic stem cell transplant as the next treatment step, researchers also evaluated the ability to mobilize and collect the patients' peripheral blood stem cells after the drug therapy was administered. They were successful in 20 of 21 patients.

Budde said the next step is to conduct a phase 2 study of patients who have diffuse B-cell lymphoma because the drug regimen worked best in these patients and it is the most aggressive of lymphomas.

In addition to Budde and Gopal, study co-authors included researchers at the University of Washington; Massachusetts General Hospital, Valley Medical Center in Renton, Wash.; Great Falls Clinic in Great Falls, Mont.; and Yakima Regional Medical & Cardiac Center in Yakima, Wash.

The National Institutes of Health, Lymphoma Research Foundation, Leukemia and Lymphoma Society, the Mary A. Wright Memorial Research Fund, Washington Life Sciences Discovery Fund, and Merck Sharp & Dohme Corp. funded the study.