A Phase I Study of Escalated Dose Subcutaneous Alemtuzumab Given Weekly with Rituximab In Relapsed CLL/SLL.

Alemtuzumab is an anti-CD52 antibody originally approved for intravenous administration three times per week to CLL patients refractory to fludarabine and previously exposed to alkylators. Since that time subcutaneous administration three times per week has become widespread because of its reduced infusional toxicity and recently demonstrated equivalent efficacy. In this study we assessed the tolerability, efficacy and pharmacokinetics of administering alemtuzumab subcutaneously weekly at up to 90 mg per dose following an initial 3+3 dose escalation (see table); we further added weekly rituximab in hopes of enhancing activity in lymph nodes. Treatment was administered in up to two eight week blocks with response evaluation between; the second 8 week block continued the dose and schedule used in weeks 5–8. No more than 45 mg was given per subcutaneous injection site.

28 patients were enrolled on this study between 7/2006 and 1/2010. The median age was 62 (range 47–76), and 75% were male. The median time from diagnosis to starting study therapy was 94 mos (14-236 mos). A majority of patients (82%) had Rai stage 3–4 disease and the median number of prior therapies was 4 (1-11). 20/28 patients (71%) had high risk deletions of 17p or 11q. 13/16 (81%) had unmutated IGVH, and 14/19 (74%) were positive for ZAP70. Early study withdrawals occurred due to pre-existing and persistent thrombocytopenia requiring study therapy to be held (n=2), persistent fever attributed to alemtuzumab (n=1), PML in retrospect present prior to study entry (n=1), and a DLT (grade 3 rituximab reaction) which was observed on dose level 2 prior to dose escalation of alemtuzumab. Overall, therapy was well tolerated; injection site reactions were minimal, primarily grade 1 (n=11) with only two grade 2 events. Other toxicities were as expected with alemtuzumab in this patient population, including grade 3–4 neutropenia (54%), grade 3–4 thrombocytopenia (57%), and single cases each of grade 3 rash, AIHA, pulmonary embolism, MRSA bacteremia, diverticular abscess, pulmonary Cryptococcus, EBV lymphoma and metastatic colon cancer. The ORR by NCI-WG criteria at wk 8 was 61% (95% CI 42–76%), with CR rate 11% (95% CI 4–27%). Two of 14 patients who completed a second eight week cycle improved their response (one PR from SD, and one CR from PR). A planned endpoint of this study was to compare lymph node staging by CT to PE, and we found that using CT scans to evaluate nodal response at 8 weeks decreased the ORR rate to 14% (95% CI 6–31%), with no CRs. Bone marrow was completely cleared of disease by 8 weeks in 8 patients and by 16 weeks in an additional 4 patients. The median PFS for the entire population was 13 months with a median follow-up of 9 months in patients who have not progressed. 10 patients have died, 5 of disease, 3 of second malignancies, 1 of PML and 1 of SCT complications. The median OS from study entry is 47 months, with 10 patients having undergone subsequent SCT. Following initiation of therapy we observed a >1,700X decrease in the median CD19⁺5⁺ cell count in peripheral blood by the start of week 3. Similar rapid depletion of all T and NK cell subsets was also observed, with first signs of recovery at week 28, and more definite recovery at week 40. Preliminary pharmacokinetic data demonstrated lower maximum levels of rituximab (p=0.06) and alemtuzumab (p=0.05) in patients with >80% bone marrow replacement by CLL but not in those with bulky lymphadenopathy. A trend toward higher alemtuzumab levels was observed in those patients with complete bone marrow clearance (p=0.1) but not in those with objective response. In conclusion, we found that administration of alemtuzumab at 90 mg subcutaneously weekly in combination with rituximab was well-tolerated, convenient and resulted in sustained adequate blood levels of both drugs in most patients. Response rates were high although in this relapsed refractory CLL population, abdominal lymphadenopathy was common, resulting in a decreased response rate when CT scans were included in staging. PFS and OS were favorable for this novel combination regimen and many patients went on to SCT.

Brown:Genzyme: Research Funding; Celgene: Consultancy, Research Funding; Calistoga: Consultancy; Genentech: Consultancy. Off Label Use: alternative schedule of alemtuzumab. Kipps:GlaxoSmithKline: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Genentech: Research Funding; Celgene: Consultancy, Membership on an entity's Board of Directors or advisory committees; Celgene: Research Funding; Genzyme: Research Funding; Memgen: Research Funding; Igenica: Consultancy, Membership on an entity's Board of Directors or advisory committees; Sanofi Aventis: Research Funding; Abbott Laboratories: Research Funding.