Life after Fludarabine, Cyclophosphamide, & Rituximab (FCR) - the Clinical Outcome of Patients with Chronic Lymphocytic Leukemia Who Receive Salvage Treatment after Frontline FCR.
Authors: Tam Constantine S. , Wierda William G. , O’Brien Susan , Lerner Susan , Khouri Issa F , Kantarjian Hagop M. , Keating Michael J 
Published: April 2020

Abstract
The FCR regimen is the most active treatment program in CLL, with 72% of frontline patients achieving a complete remission (CR) lasting a median of 7 years. However, most patients are not cured and will eventually relapse with CLL. In order to evaluate how these patients should be subsequently managed, we analyzed our institutional experience with 300 patients treated with frontline FCR (Blood 112:975). After a median follow-up of 6 years, 116 patients (39%) had failed FCR therapy with 13 primary refractory disease and 103 relapses from partial remission (PR), nodular PR (nPR) or CR. Compared with patients in ongoing remission, relapsed/refractory patients had more adverse baseline characteristics including a greater proportion with performance status ≥ 1 (71% vs 53% p=0.002), elevated β2m (54% vs 36% p=0.002), white cell count ≥ 150 x 10^9/L (25% vs 12% p=0.003), unmutated IgVH (81% vs 44% p&lt;0.001) and ZAP-70 positivity (78% vs 49% p&lt;0.001). The aim of the current analysis was to determine the duration of survival (OS) following second-line therapy in 97 patients who had completed salvage treatment. The median follow-up was 32 (range 3 – 69) months, and the median OS (mOS) was 32 months. Characteristics associated with favorable OS were: (1) previous best response to FCR of nPR/CR lasting ≥ 18 months (mOS 47 months, vs 13 months for primary refractory disease, PR or nPR/CR lasting &lt;18 months p=0.002); (2) β2m &lt; 3.0 mg/L (mOS not reached, vs 17 months p=0.0003) and (3) platelets ≥ 100x10^9/L (mOS 47 months, vs 15 months p=0.004). Poor risk cytogenetic abnormalities were common at FCR failure: among 38 assessable patients, 7 (18%) had 17p- and 18 (47%) had 11q- by conventional karyotyping and/or FISH. Although patients with 17p- or 11q- had an inferior survival, this survival disadvantage was confined entirely to those who also had an elevated β2m ≥ 3.0 mg/L. Surprisingly, patients relapsing after durable FCR remissions (≥ 5 years) and patients with slowly progressive relapse (time to salvage ≥ 12 months after FCR failure) had similar OS as their more adverse counterparts (p=0.76 and 0.86 respectively). A prognostic model comprising β2m and platelet count effectively divided patients into low, intermediate and high risk categories with mOS of &gt;45, 32 and 13 months respectively (p&lt;0.0001). Patients received treatment chosen at the discretion of individual treating physicians and the CR rate of second-line therapy were: FCR (n=30), 17%; rituximab (n=25), 4%; alemtuzumab ± rituximab (n=16), 31%; FCR & alemtuzumab (CFAR, n=9), 56%; lymphoma-type chemotherapy (n=5), 0%; other treatment (n=12), 0%. The CR rate for CFAR was significantly higher than that of FCR (p=0.03), although the median remission duration (30 vs 20 months) and OS (44 vs 32 months) were similar (p=0.87 and 0.51 respectively). None of the regimens showed a significant survival benefit. Allogeneic stem cell transplantation (SCT) was performed in 27 (28%) patients at a median of 15 months after first salvage. Patients receiving SCT had a significantly superior OS than those who did not undergo SCT (not reached vs 30 months, p=0.03). Of the 14 patients surviving for more than four years, 11 (79%) had undergone a SCT. Patients who fail FCR therapy had high risk disease features including elevated β2m, unmutated IgVH and ZAP-70 positivity, and most had adverse cytogenetic findings at relapse. Results of salvage therapy in this group were poor with a median survival of less than three years. The majority of long-term survivors had received allogeneic stem cell transplantation.