Merck, commonly known as MSD, has obtained breakthrough therapy designation from the US Food and Drug Administration (FDA) for its Keytruda (pembrolizumab) to treat patients with relapsed or refractory classical Hodgkin lymphoma (cHL).

Hodgkin lymphoma is a specific type of lymphoma and includes two subtypes: cHL and nodular lymphocyte predominant Hodgkin lymphoma.

Lymphoma is a type of blood cancer that affects the lymphatic system, which removes excess fluids from the body and produces immune cells.

Lymphoma cells are abnormal lymphocytes that multiply and collect in the lymph nodes and other tissues.

Keytruda is a humanised monoclonal antibody that increases the ability of the body's immune system to help detect and fight tumour cells.

It activates T lymphocytes that may affect both tumour cells and healthy cells, by blocking the interaction between PD-1 and its ligands, PD-L1 and PD-L2.

Merck Research Laboratories president Dr. Roger M. Perlmutter said: "Merck has launched an ambitious clinical development programme examining the efficacy of Keytruda in a broad range of solid and blood cancers, and our studies of relapsed or refractory classical Hodgkin lymphoma are quite promising.

"The FDA's breakthrough designation for this blood cancer provides an important mechanism to assist us in bringing this immunotherapy to patients who could benefit from its use."

The designation has been provided based on a data from ongoing Phase Ib KEYNOTE-013 and Phase II KEYNOTE-087 studies, which assessed efficacy of Keytruda.

Keytruda also obtained breakthrough status to treat specific patients with advanced melanoma, advanced non-small cell lung cancer (NSCLC), and advanced colorectal cancer.