Thalidomide (T) in Combination with Fludarabine (F) as Initial Therapy for Patients (pts) with Treatment Naïve Chronic Lymphocytic Leukemia (CLL): Results of a Phase I Trial.

CLL is an incurable disease. Standard treatment with F results in an ORR of 63% (CR 20%). Improved RR are noted when F is combined with biologic agents such as rituximab. All pts eventually relapse with limited salvage options. TNF-a is an important cytokine in the pathogenesis of CLL. T is an immunomodulatory drug with anti- TNF-a, anti-VEGF and immunostimulatory activity. We have completed a phase I study combining T with F as an immunochemotherapeutic approach to enhance anti-CLL activity of F. Treatment-naïve pts requiring therapy for CLL were eligible for this study. T was started at D1 and continued for 6 months stepwise in 3 cohorts of T (100,200,300 mg). Standard dose F (25mg/m² x 5 D every 4 wks) was given for 4–6 cycles starting on D7. Antitumor activity of T alone was assessed at D7 prior to the first F dose. Low-dose coumadin (1 or 2 mg po qd) was used for prophylaxis against venous thromboembolism (VTE). Thirteen pts (9M, 4F; median age 65,range 38–74 yrs) have been enrolled on 3 dose levels (cohort #1 n =6, #2 n=3, #3 n=4). All pts are available for toxicity analysis. Pts were considered evaluable for response if they completed the intended 6 months of T. 3 pts were removed from study for toxicity (2VTE, 1 in the 1st week of therapy prior to F infusion, 2^nd during the 4^th cycle, 1 Hep C reactivation presumably secondary to F), without evidence of disease progression. 9 pts completed 6 months of therapy and are available for response (5CR and 4PR, ORR of 100%) median follow-up of 12+ (range 6–18+) months. Response to T alone, assessed on D7 of cycle 1, was noted at all dose levels, and no dose-limiting toxicity was noted. Flare reaction (tender swelling of lymph nodes) was noted in 5/13 pts (38%) and was the most common side effect. Rash, fatigue and constipation were noted in 30%, 23% and 15% of the pts, respectively. Of the 60 cycles given on this study, 9 (15%) and 3 (5%) episodes of Grade III and IV non-hematologic toxicities were noted, respectively. In this phase I study, the combination of T with F was well tolerated with improved ORR over F. T alone appears to be active in CLL with clinical activity noted as early as D 7 at all dose levels studied. The combination does not appear to increase the incidence of VTE compared to T alone. Ongoing phase II portion of this study will further establish the potential role of FT in CLL.