Treatment with Fludarabine and Rituximab Produces Extended Overall Survival (OS) and Progression-Free Survival (PFS) in Chronic Lymphocytic Leukemia (CLL) without Increased Risk of Second Malignancy: Long-Term Follow up of CALGB Study 9712

Abstract 539 Introduction: The addition of rituximab to fludarabine-based regimens in CLL has been shown to produce high response rates with extended remissions. The long-term follow-up of these regimens with respect to progression, survival, and development of secondary malignancies has been limited. Patients and Methods: We report the long-term follow up of the chemoimmunotherapy trial CALGB 9712 (Blood 2003;101:6-14). This trial randomized 104 untreated, symptomatic patients to receive either 6 monthly cycles of fludarabine plus rituximab (FR) followed 2 months later by 4 weekly doses of rituximab (concurrent arm) or 6 monthly cycles of single agent fludarabine followed by rituximab consolidation using 4 weekly doses (sequential arm). With a median follow up of 92 months (range: 60-107), we analyzed the updated CALGB database and flow sheets submitted by treating physicians. Results: The overall response rate (ORR) was 84% (95% CI: 77%-91%), with a 90% ORR in the concurrent group (95% CI: 82%-98%) and a 77% ORR in the sequential group (95% CI: 66%-89%). Complete response (CR) was seen in 38% of patients (95% CI: 30%-45%), and partial response (PR) in 46% (95% CI: 38%-54%). The median OS was 85 months (95% CI: 71-95), with 71% of patients alive at 5 years (95% CI: 61%-79%). The median PFS was 37 months (95% CI: 27-45), with 27% progression-free at 5 years (95% CI: 19%-36%). With long-term follow up, the estimated median OS and PFS for the concurrent group were 84 months (95% CI: 57-100) and 32 months (95% CI: 23-55), respectively; the median OS and PFS for the sequential group were 91 months (95% CI: 71-110) and 40 months (95% CI: 23-50), respectively. Patients with del(17p13.1)/del(11q22.3)(18 patients) and unmutated IgVH(43 patients) continue to have an inferior OS (P=0.01 and P=0.04, respectively) and PFS (P=0.03 and P=0.04, respectively) compared to those without these abnormalities. We next assessed the frequency of therapy-related myeloid neoplasms (t-MN) and other cancers occurring after this chemoimmunotherapy regimen. No patient has developed MDS or AML prior to relapse. One patient (1%) developed t-MDS following relapse and receipt of FCR 41 months after completing trial therapy; t-MDS was diagnosed 9 months later. Richter's transformation was noted in three (3%) of the CALGB 9712 patients with large cell (n=2) or Hodgkin lymphoma (n=1). Second malignancies have included localized basal cell or squamous cell skin cancer in 12 (12%) patients whereas 11 (11%) have developed other epithelial malignancies including 4 GI, 3 lung, 3 melanomas, and 1 prostate cancer. Conclusions: Long-term follow up of patients enrolled on CALGB 9712 demonstrates extended OS and PFS with fludarabine plus rituximab, given either concurrently or sequentially, with an estimated 17%(95% CI: 9%-27%) of responders still in remission 8 years later. Looking at other published data, patients treated with FR administered concurrently or sequentially do not appear to have an increased risk of t-MN or second cancers. These long-term data reaffirm that FR is one of several acceptable frontline treatments for symptomatic patients with CLL. Disclosures: Morrison: Genentech: Speakers Bureau.