17p deletion—A genetic change (also called a mutation) in which part of chromosome 17 is missing in some CLL cells. 17p deletion in people with CLL is associated with poor response to chemotherapy.

Anemia—Fewer than normal red blood cells in the blood.

B lymphocytes—A type of white blood cell that helps the body fight infection.

BCL-2—A specific protein that may build up in cells and prevent apoptosis, which means it may prevent cancer cells from self-destructing naturally. VENCLEXTA works by blocking BCL-2.

Bone marrow—The spongy liquid center of the bones.

Chemotherapy—A treatment that uses powerful chemicals to kill fast-growing cells in your body.

CLL—CLL, or chronic lymphocytic leukemia, is a usually slow-growing blood cancer that affects B cells, also called B lymphocytes. B cells are a type of white blood cell that helps fight infection.

CBC—Complete blood count. A routine blood test that checks the level of your cells.

CR —Complete remission. This means that all signs and symptoms of cancer disappeared for a period of time, although cancer may still be in your body.

CRi—Complete remission with incomplete marrow recovery. This means that signs and symptoms of cancer disappeared for a period of time except that platelet, white blood cell, or red blood cell counts remained low.

Leukemia—Cancer of the cells that make up your blood. Usually leukemia is a cancer of the white blood cells, but can affect other blood cell types. CLL and SLL are types of leukemia.

Lymph nodes—Filters throughout the body that trap substances and contain white blood cells, which fight infection and disease.

Neutropenia—Fewer than normal white blood cells in the blood.

nPR—Nodular partial remission. This means that most signs and symptoms of cancer disappeared for a period of time except for some remaining cancer cells in your bone marrow.

Platelets—Cells that make up part of the blood. Platelets help form blood clots from injuries such as cuts, scrapes, or bruises.

PR—Partial remission. This means the cancer is greatly improved and there are fewer cancer cells, but evidence of the cancer is still in your body.

Progression-free survival rate—This is the percentage of people who remain alive and who did not experience a worsening of the disease during or after treatment.

Red blood cells—Cells that make up part of the blood. Red blood cells carry oxygen to other cells throughout the body.

Refractory—When cancer doesn’t respond or stops responding to a treatment.

Relapsed—When a treatment works for a while, but after some time the cancer returns.

Remission—A decrease in or disappearance of signs and symptoms of cancer.

SLL—SLL, or small lymphocytic lymphoma, is closely related to CLL. However, SLL cancer cells are mostly found in the lymph nodes rather than in the blood and bone marrow.

White blood cells—Cells that make up part of the blood. White blood cells help the immune system fight bacteria and viruses.