Study Supports Use of Rituximab-containing Therapies in CAD

Therapies that contain Rituximab may be effective for people with cold agglutinin disease (CAD), a study suggests.

The study, “Rituximab-containing therapy for cold agglutinin disease: a retrospective study of 16 patients,” was published in Scientific Reports.

CAD is caused by cold agglutinins — a type of self-targeting antibody that binds to red blood cells (RBCs) at low temperatures, leading to their destruction and anemia.

Specific medicines for CAD patients remain scarce. Also, as the disease is rare, clinical trials of potential therapies face challenges of recruiting a large enough group of participants.

Rituximab works by killing B-cells, the immune cells primarily responsible for antibody production. The therapy is approved to treat certain types of blood cancers, among other indications. Rituximab also is used as a first-line treatment for CAD, either alone or in combination with other medicines.

Here, researchers from China reported data for 16 people with CAD who were treated with a rituximab-containing therapy at Peking Union Medical College Hospital for at least one month between 2012 and 2019. Of the 16 participants, 11 were men, five were women, and the median age at symptom onset was 63.5 years.

Most patients had cold-induced circulatory symptoms (75%) and manifestations related to anemia such as fatigue and weakness (81.3%). Five (31.3%) received RBC transfusions before therapy.

Six individuals received rituximab with or without the corticosteroid prednisone. The remaining 10 received one of the following combinations: rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone (R-CHOP, one person); rituximab, cyclophosphamide, vincristine, and prednisone (R-CVP, two people); dexamethasone, rituximab, and cyclophosphamide (DRC, three patients); and rituximab, fludarabine, and cyclophosphamide (RFC, four participants).

A complete response to therapy included disappearance of clinical symptoms of CAD, absence of anemia, no signs of RBC death, and normal bone marrow assessments. A partial response to therapy was defined as a stable increase in hemoglobin levels, a decrease in cold agglutinin levels, and eased clinical symptoms, without the need for transfusions. (Hemoglobin is the protein that carries oxygen in the bloodstream.)

Individuals who did not meet the criteria for a complete or partial response were labeled as no response.

In total, 13 (81%) of the participants had a partial response, three of whom fulfilled all complete response criteria except for the bone marrow assessment.

The remaining three patients were labeled as no response. One of these individuals showed a decrease in anemia-related symptoms, but did not fulfill the criteria of partial response, the researchers said.

Response rates of treatment with rituximab (with or without prednisone) did not differ significantly from combination therapies.

The most commonly reported adverse event (side effect) was severe or life-threatening neutropenia (a decrease in a type of immune cell called neutrophils), seen in three participants. Yet, only one of these patients experienced an infection. In addition, one participant had anaphylaxis — a severe allergic reaction — in response to rituximab.

“Regarding the safety of the therapy, our study shows acceptable outcomes,” the researchers wrote. “Thus, we think it reasonable to choose a rituximab-based therapy in accordance with individual patient characteristics, weighing the efficacy and tolerance of the treatment.”

Median progression-free survival, or the time without disease progression, was 36 months (three years).

The median follow-up time was 16 months. During this period, five participants experienced relapses. Three of these relapses were treated successfully with rituximab-containing therapies, and one was controlled successfully with another B-cell-targeting therapy, zanubrutinib (sold as Brukinsa for adults with mantle cell lymphoma).

The remaining individual who relapsed died of disease progression five months after starting treatment, before additional treatments could be administered. One other individual died during follow-up, but the cause of death was not known.

According to the investigators, study limitations include the low number of participants and the fact that different rituximab-containing therapies were all analyzed together.

“In conclusion, our study shows a favourable effect of rituximab-containing therapy in patients with CAD,” the researchers wrote. Yet, “it is difficult to determine which specific regimen is better, and further prospective trials are required to optimize the therapy.”