• Recent studies indicate that engaging in moderate to vigorous physical activity may enhance the effectiveness of rituximab, a monoclonal antibody therapy used in treating chronic lymphocytic leukemia (CLL).
• Researchers based in England discovered that such exercise prompted a rise in natural killer cells, which, when combined with rituximab, help target and destroy cancerous cells in the bloodstream.
• Although experts acknowledge the growing evidence suggesting the immune-boosting capacity of exercise in fighting cancer, they emphasize that the small number of participants in this study limits the broader applicability of the findings.

A new study reveals that short bursts of high-intensity exercise may improve the potency of rituximab, an antibody used commonly in treating chronic lymphocytic leukemia (CLL).

Experts from the Universities of Birmingham and Bath in the UK recently shared their findings in the journal Brain, Behavior, and Immunity, where they explored exercise’s impact on a cohort of 20 CLL patients.

These participants, none of whom had previously undergone cancer treatment, participated in cycling sessions lasting 20 to 30 minutes as part of the study.

Moderate to vigorous cycling during these sessions elevated the number of natural killer cells—a key type of anti-cancer immune cell—by as much as 254%.

When combined with rituximab, which binds to proteins on the cancer cells, effectively helping natural killer cells recognize and eliminate them, the post-exercise samples demonstrated that these immune responses were twice as effective.

“This is the first research to showcase how a single bout of intense cycling enhances rituximab-facilitated ADCC [antibody-dependent cellular cytotoxicity] against self-derived CLL cells in a lab setting,” the authors write.

They further note a unique observation: “This marked increase and mobilization of CD5+CD19+ CLL cells and their subtypes in response to vigorous cycling are novel. CLL cells exhibit similarities to healthy B-cells, such as possessing CD19 markers, and in healthy individuals, these B-cell levels may increase up to 100% after similar cycling exercises.”

Questions remain on exercise's exact role in cancer treatment

Dr. Catherine S. Diefenbach, director of the Clinical Lymphoma Program at Perlmutter Cancer Center, NYU Langone Health, provided her perspective to Medical News Today on the study, noting that while the results are promising, there’s significant uncertainty owing to the small sample size.

“This pilot study involving 20 patients in a highly controlled setting — where exercise is introduced in a specific, measured manner — offers interesting biological insights, demonstrating active NK cell function and improved CLL cell targeting via Rituxan [rituximab],” Diefenbach stated.

However, she warned, “The results must be confirmed in broader studies with more diverse patient populations. Moreover, it remains unclear if these findings influence the actual clinical progression of CLL, particularly regarding response to therapy or disease management.”

She emphasized, “The study primarily highlights enhanced CLL cell death through Rituxan but does not provide evidence that exercise impacts overall disease outcomes. Currently, I’m unaware of any cancer trials that have definitively proven a positive impact of physical activity on clinical results.”

Dr. Wael Harb, a board-certified oncologist at MemorialCare Cancer Institute in Orange County, California, who also was not involved with the study, echoed these sentiments and raised additional questions regarding practicality.

“There’s a fundamental issue with applying these findings broadly,” Harb noted. “Patients who can perform high-intensity exercises might already have healthier immune systems than those who aren’t able to. This limitation, along with the study’s size, makes it hard to draw wide-reaching conclusions.” Harb also expressed caution about interpreting data from in vitro experiments when compared to real-world bodily responses.

“The critical question is whether these results translate into long-term clinical benefits,” he added. “We need longitudinal studies to determine if exercise contributes to better treatment responses, longer remission periods, or symptom relief in leukemia patients. Studying this further will require randomized trials where exercise is carefully integrated into standard treatment protocols.”

– Dr. Wael Harb

How might physical activity affect cancer treatment?

Cancer therapies like chemotherapy and surgery often induce extreme fatigue, yet more evidence is emerging to suggest that exercise may activate immune cells.

Dr. Harb explained that physical activity is widely known for its ability to boost immune function, and some recent studies have investigated how both short bursts and regular exercise routines influence cancer progression.

“We encourage regular physical activity and exercise as part of cancer treatment protocols, as there is increasing evidence that supports their role in strengthening the immune system,” he commented. “Over the years, we’ve realized how critical the immune system is in combating cancer.”

“In fact,” Harb added, “many innovative therapies today are designed to harness the power of the immune system to fight cancer. However, there are still some challenges regarding the intensity of exercise that can be safely recommended.”

“The idea of vigorous exercise raises concerns since not every patient can participate in high-intensity activity, particularly depending on age or accompanying health conditions,” Harb pointed out. “Further research should focus on balancing practical considerations while exploring how physical activity enhances treatment outcomes.”

– Dr. Wael Harb