Tumor Lysis Syndrome (TLS): TLS, including death, has been reported in patients receiving GAZYVA. GAZYVA works to break down cancer cells quickly. As cancer cells break apart, their contents are released into the blood. These contents may cause damage to organs and the heart, and may lead to kidney failure requiring the need for dialysis treatment. Your doctor may prescribe medication to help prevent TLS. Your doctor will also conduct regular blood tests to check for TLS. Symptoms of TLS may include nausea, vomiting, diarrhea, and tiredness