Abstract

Abstract 1383

Introduction:

Lenalidomide (L) has activity in relapsed chronic lymphocytic leukemia (CLL). The mechanism of action is not well understood but may involve stimulation of anti-leukemic immune responses. Myelosuppression especially neutropenia is a concerning side effect. We reasoned that pulsed dosing of lenalidomide could reduce myelosuppression while maintaining the immune stimulatory effect. To test this concept we initiated a single center, phase II trial (ClinicalTrials.gov Identifier: NCT00465127) of lenalidomide given in cycles of 3 weeks on, 3 weeks off drug (42 day cycles).

Methods:

Patients (pts) with relapsed CLL or small lymphocytic lymphoma with ANC>500/ul and platelets >20,000/ul were eligible. The primary endpoint defined as response after 4 cycles has been recorded for all participants. Pts with partial response were allowed to receive up to 4 additional cycles. The starting dose for the first 10 pts was 20 mg daily; the starting dose for pt 11 onwards was lowered to 10 mg daily because of toxicities observed in other L trials for CLL. TLS prophylaxis with Allopurinol was mandated during cycle 1–3. Deep venous thrombosis (DVT) prophylaxis was not mandated unless risk factors were present. Ibuprofen and corticosteroids were allowed to treat symptoms of a cytokine release syndrome (CRS, defined by LN swelling, fever, fatigue, pain, chills, dehydration). Responses were assessed by IWCLL criteria and included CT scanning. Patient characteristics (n=33) were: median age 64 years (36-78); median number of prior therapies 3 (range 1–7); 52% Rai stage III-IV; 70% bulky disease; 30% fludarabine refractory; 56% (of 27 pts) ZAP70 pos; 64% (of 25 pts) unmutated immune globulin VH mutation status; 43% del 17p; 15% del 11q.

Results:

A total of 131 cycles of L were given. 31 pts received at least 2 cycles of therapy (range 2–8) and were evaluable for response: 5 (16%) partial response (PR), 18 (58%) stable disease, and 8 (26%) progressive disease. 4 of 5 responding pts had del 17p and bulky disease. In responders (n=5, PR) vs non responders (n=26, SD+PD) the PFS was 16 vs 6 months (p>0.01), and the time to next therapy was 17 vs 6 months (p>0.01), respectively. Once treatment was stopped, duration of response was short lived (median 6 months, range 2–18). 4 out of 5 responders were observed in the 20 mg dose starting group versus only 1 responder in the 10 mg group (p=0.03). There was no difference in the CRS score between the 2 groups (2.5 vs 1.5, p=0.17). Hematologic responses were observed in 11 out of 24 CLL pts (45%). At the completion of 4 cycles CD4 and CD8 counts increased by 20%, while NK cell counts remained unchanged. Dose modifications/withdrawl: 41% of cycles required dose adjustments prior to or during cycles 1–4. 9 pts (27%) did not complete 4 cycles of L because of: autoimmune cytopenias (2 pts), side effects (4 pts; CRS 1 pt, neutropenia 3 pts), withdrawal from study (2 pts), and disease progression (1 pt). Toxicity: Gr 3/4 neutropenia was observed in 56% of 131 cycles, often worsening with cumulative cycles. Gr 3/4 thombocytopenia and anemia were seen in 30% and 15% of cycles, respectively. Gr 1/2 and 3/4 infections occurred in 23% and 11% of cycles, respectively, 8 of those in the setting of neutropenia. Gr 3 CMV colitis, PCP pneumonia and Candedemia each were observed once. 1 patient died from streptococcal sepsis in cycle 4. Gr 1/2 and 3/4 CRS were observed in 43% and 10% of cycles, respectively. A CRS was encountered in 78% of first cycles typically within the first week, and in 48%, 38% and 30% of cycles 2–4, respectively. 6 DVTs (Gr 3) were diagnosed in 5 pts. Other common side effects were fatigue (62%), rash (39%) and muscle cramps (27%), all Gr 1/2. No case of tumor lysis syndrome was seen.

Conclusion:

L cycled 3 weeks on, 3 weeks off led to stable disease in the majority of pts and induced PRs in 16% of relapsed CLL patients with high risk disease. Pulse dosing of L did not lead to reduced toxicities. Myelosuppression and infections remain a major concern. 4 out of 5 responders were observed in the 20 mg cohort arguing for higher L starting doses. Notably, side effects, particularly the CRS, were similar in the two cohorts. Once L was discontinued, the duration of response was short, suggesting a need for continued therapy in pts who are able to tolerate the drug.

Disclosures:

Off Label Use: Lenalidomide is not FDA approved in Chronic Lymphocytic leukemia.

Author notes

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Asterisk with author names denotes non-ASH members.