Pilot experience with continuous infusion alemtuzumab in patients with fludarabine-refractory chronic lymphocytic leukemia

Alemtuzumab use in relapsed and refractory chronic lymphocytic leukemia: a history and discussion of future rational use

In this review, we outline the clinical experience with single-agent alemtuzumab as a treatment for relapsed and refractory chronic lymphocytic leukemia (CLL) in both prospective and retrospective trials and describe the multiagent use of the drug with the goal of updating clinicians on recent developments and possible future rational combinations. Alemtuzumab, an antibody targeting the lymphocyte-specific surface marker CD52, is an approved agent for the treatment of CLL. Despite its demonstrated efficacy, likely secondary to concerns regarding infectious complications, it is most commonly used in the relapsed and refractory setting. Given alemtuzumab's unique mechanism of action it has been demonstrated to have activity in disease that is refractory to both alkylating agents and purine analogs. Furthermore, it has activity in TP53-mutated disease, which has the worst prognosis of any subset of CLL. Alemtuzumab has greater efficacy on circulating disease relative to nodal disease. Rational combinations are attempting to use these attributes to increase response rates in patients with relapsed and refractory disease.

Alemtuzumab by continuous intravenous infusion followed by subcutaneous injection plus rituximab in the treatment of patients with chronic lymphocytic leukemia recurrence

BACKGROUND

Monoclonal antibodies may be used more effectively in combination. A previous study of intravenous (iv) bolus alemtuzumab plus rituximab in patients with chronic lymphocytic leukemia (CLL) recurrence produced a response rate of 54% after a 4-week treatment period.

METHODS

To optimize dose, schedule, and route of alemtuzumab, a study was designed exploring continuous intravenous infusion (civ) followed by subcutaneous (sc) alemtuzumab together with weekly iv rituximab in patients with previously treated CLL.

RESULTS

Data from 40 patients with a median age of 59 years, and a median of 3 prior regimens (range, 1-8 regimens) were evaluable. Approximately 64% of patients were fludarabine-refractory. Seven patients (18%) achieved a complete response (CR), 4 (10%) a nodular partial response (nPR), and 10 (25%) a partial response for an overall response rate of 53%. Of 11 major responses (CR, nPR), 8 occurred after cycle 1. Response rates were highest in blood (94%), followed by liver/spleen (82%), bone marrow (68%), and lymph nodes (51%). The combination did not generate unexpected toxicities. Cytomegalovirus (CMV) reactivations occurred in 6 patients (15%) and responded well to anti-CMV therapy. High titers of anti-idiotype antibodies after sc alemtuzumab were demonstrated in 1 patient, but remained without clinical sequelae.

CONCLUSIONS

The combination of civ/sc alemtuzumab plus rituximab has activity in some patients with recurrent/refractory CLL and maximum response is achieved after 1 cycle (4 weeks) in 73% of patients. Further exploration in other settings of CLL together with accompanying pharmacokinetic studies is recommended.