Lymphoma is a cancer that begins in cells of the immune system, in particular in the lymph system, an interconnected network of vessels and nodes that circulate a fluid called lymph . The lymph is rich in lymphocytes, a type of white blood cells that help the body fight off infections and other diseases . Lymphoma occurs when lymphocytes become cancerous . The two main types of lymphomas are Hodgkin lymphoma (HL) and non-Hodgkin lymphomas (NHL), and are differentiated by the type of lymphocytes affected and their appearance under the microscope [1, 3].
Hodgkin lymphoma (HL) is a type of neoplasms of the lymph nodes and the lymphatic system, originated from a specific type of white blood cells called lymphocytes (Figure 1). These lymphoid malignancies travel to other organs such as liver, lung and bone marrow, affecting their normal function . HLs containing cells called Reed-Sternberg cells are referred to as classical Hodgkin lymphoma (CHL), and those that present lymphocyte-predominant cells are known as nodular lymphocyte-predominant Hodgkin lymphoma (NLPHL) .
Every year, HL affects around 9,000 new people in the United States . Most patients are diagnosed between 15 and 30 years, followed by another peak in adults aged 55 years or older [3, 4]. In western countries, 95% of diagnosed patients will have CHL .
Figure 1: Schematic of normal blood cells and HL development
Although the treatment for HL depends of the stage of the disease, the main treatment strategies include radiotherapy, chemotherapy and steroid therapy . Treatment advances in the past few decades provided a significant improvement in the management of patients with HL . While over 80% of patients diagnosed with this malignancy achieve complete remission after initial treatment, around 20-30% of these patients will eventually relapse [4, 6]. Treatment for relapsed and refractory HL involves high dose therapy and, in some cases, stem cell transplant . Treatment morbidity and long-term toxicity has also become an increasing concern in this patient population . Therefore, development of new therapies is highly needed for relapsed and refractory HL to improve patient’s quality of life and minimize long-term toxicities.