The treatment of CLL is evolving as several active targeted agents have emerged. Most cases of early indolent CLL require no specific therapy, and the standard of care for early-stage disease has been observation. Indications for treatment include progressive fatigue, symptomatic lymphadenopathy, anemia, or thrombocytopenia. These patients have either symptomatic and progressive Rai stage II disease or stage III/IV disease. Initial treatment for patients with CLL consists of targeted biologic therapy in most cases. Options include ibrutinib (a Bruton tyrosine kinase inhibitor targeting B-cell receptor signaling) or venetoclax (a bcl2 inhibitor resulting in apoptosis) in combination with anti-CD20 antibody therapy. Choice between these agents is based on toxicity as well as preference. Ibrutinib is a well-tolerated, oral agent given at 420 mg daily; it can be associated with hypertension, cardiac arrhythmias, rash, and increased infections. Caution should be exercised when this agent is used in conjunction with CYP3A inhibitors or inducers. In addition, there is a potential for serious bleeding when it is used in patients taking warfarin. Venetoclax (slowly titrated up to 400 mg daily) is usually given for a shorter course of therapy and is associated with tumor lysis syndrome and neutropenia; some patients may require hospitalization for initial therapy. Venetoclax has to be combined with a monoclonal CD20 antibody, usually obinutuzumab, which can result in infusion reactions. Traditional combination chemotherapy is used only in selected cases (see Table 39–3). For older patients, chlorambucil, 0.6–1 mg/kg orally every 4 weeks, in combination with obinutuzumab is another therapy option.
For patients with relapsed or refractory disease, both venetoclax and ibrutinib or another BTK inhibitor, acalabrutinib, demonstrate significant activity, even for patients with high-risk genetics. Other options include idelalisib and duvelisib (inhibitors of PI3 kinase delta), which are associated with higher toxicity. The dosage for idelalisib is 150 mg orally twice a day, and the dosage for duvelisib is 25 mg orally twice a day. There are risks for colitis, liver injury, and fatal infectious complications in patients treated with PI3k inhibitors. Patients should be given antimicrobial prophylaxis and monitored closely while taking these agents.
Of note, BTK and PI3k inhibitors can be initially associated with marked lymphocytosis due to release of tumor cells from the lymph nodes into the peripheral blood. This results in a significant early reduction in lymphadenopathy but a potentially misleading, more delayed clearance of lymphocytes from peripheral blood and bone marrow.
Associated autoimmune hemolytic anemia or immune thrombocytopenia may require treatment with rituximab, prednisone, or splenectomy. Fludarabine should be avoided in patients with autoimmune hemolytic anemia since it may exacerbate it. Rituximab should be used with caution in patients with past hepatitis B virus (HBV) infection since HBV reactivation, fulminant hepatitis, and, rarely, death can occur without anti-HBV agent prophylaxis. Patients with recurrent bacterial infections and hypogammaglobulinemia benefit from prophylactic infusions of gamma globulin (0.4 g/kg/month), but this treatment is cumbersome and expensive, justified only when these infections are severe. Patients undergoing therapy with a nucleoside analog (fludarabine, pentostatin) should receive anti-infective prophylaxis for Pneumocystis jirovecii pneumonia, herpes viruses, and invasive fungal infections until there is evidence of T-cell recovery.
Allogeneic transplantation offers potentially curative treatment for patients with CLL, but it should be used only in patients whose disease cannot be controlled by the available therapies. Nonmyeloablative allogeneic transplant can result in over 40% long-term disease control in CLL but with risk of moderate toxicity.