A look at tumor lysis syndrome in the treatment of CLL

This study reviewed the occurrence and management of tumor lysis syndrome in patients receiving treatment for chronic lymphocytic leukemia (CLL).

Tumor lysis syndrome (TLS) is an uncommon but potentially life-threatening complication associated with the treatment of some cancers. TLS occurs when a large number of cancer cells are killed at once and their byproducts enter the bloodstream. If left untreated, TLS can lead to acute kidney failure, heart rate problems, neurological complications, and seizures. TLS has not commonly been observed in CLL patients treated with chemotherapies. New targeted therapies, such as idelalisib (Zydelig), ibrutinib (Imbruvica), and venetoclax (Venclexta), can cause rapid tumor reduction. This may increase the risk of TLS in CLL patients.

Approaches for preventing TLS include laboratory monitoring, drugs that lower the levels of uric acid (waste product caused by breaking down substances from food) in the blood, and proper hydration.

Risk of TLS is determined by tumor size, tumor breakdown, and symptoms. Other risk factors include additional medical conditions such as kidney disease, an enlarged spleen, dehydration, and low blood pressure.

Different therapies may also be associated with varying risk of TLS. For example, risk of TLS with venetoclax is often higher compared to other targeted therapies. A review of a number of studies concluded that tumor burden and reduced kidney function can identify patients treated with venetoclax at high risk of developing TLS. One study reported that 2 out of 45 CLL patients (4.4%) developed TLS after treatment with lenalidomide (Revlimid). No cases of TLS have been reported with idelalisib.

Hospitalization should be considered for patients at high risk of TLS. Patients at high risk should be monitored every 4 to 6 hours after starting therapy. Patients at medium risk should be monitored every 8 to 12 hours.

Adequate hydration and a high urine output (of at least 100 ml per hour) should be ensured before starting therapy. The general recommendation for patients treated with chemotherapy is that patients should continue to be monitored for at least 24 hours after finishing chemotherapy. Similar monitoring with new targeted therapies is important. While stepping up the dosage of venetoclax on the first 5 weeks of therapy, laboratory values should be monitored at 6 to 8 hours and for 24 hours after each new weekly dose. 

This study concluded that the overall incidence of TLS is low in CLL patients. However, the risk of TLS should be determined before starting therapy and monitored accordingly.