Anna Maria Fink

Despite promising results with targeted drugs, chemoimmunotherapy with fludarabine, cyclophosphamide (FC), and rituximab (R) remains the standard therapy for fit patients with untreated chronic lymphocytic leukemia (CLL). Herein, we present the long-term follow-up of the randomized CLL8 trial reporting safety and efficacy of FC and FCR treatment of 817 treatment-naïve patients with CLL. The primary end point was progression-free survival (PFS). With a median follow-up of 5.9 years, median PFS were 56.8 and 32.9 months for the FCR and FC group (hazard ratio [HR], 0.59; 95% confidence interval [CI], 0.50-0.69, P < .001). Median overall survival (OS) was not reached for the FCR group and was 86.0 months for the FC group (HR, 0.68; 95% CI, 0.54-0.89, P = .001). In patients with mutated IGHV (IGHV MUT), FCR improved PFS and OS compared with FC (PFS: HR, 0.47; 95% CI, 0.33-0.68, P < .001; OS: HR, 0.62; 95% CI, 0.34-1.11, P = .1). This improvement remained applicable for all cytogenetic subgroups other than del(17p). Long-term safety analyses showed that FCR had a higher rate of prolonged neutropenia during the first year after treatment (16.6% vs 8.8%; P = .007). Secondary malignancies including Richter's transformation occurred in 13.1% in the FCR group and in 17.4% in the FC group (P = .1). First-line chemoimmunotherapy with FCR induces long-term remissions and highly relevant improvement in OS in specific genetic subgroups of fit patients with CLL, in particular those with IGHV MUT. This trial was registered at www.clinicaltrials.gov as #NCT00281918.

Mutations in TP53, NOTCH1, and SF3B1 were analyzed in the CLL8 study evaluating first-line therapy with fludarabine and cyclophosphamide (FC) or FC with rituximab (FCR) among patients with untreated chronic lymphocytic leukemia (CLL). TP53, NOTCH1, and SF3B1 were mutated in 11.5%, 10.0%, and 18.4% of patients, respectively. NOTCH1(mut) and SF3B1(mut) virtually showed mutual exclusivity (0.6% concurrence), but TP53(mut) was frequently found in NOTCH1(mut) (16.1%) and in SF3B1(mut) (14.0%) patients. There were few significant associations with clinical and laboratory characteristics, but genetic markers had a strong influence on response and survival. In multivariable analyses, an independent prognostic impact was found for FCR, thymidine kinase (TK) ≥10 U/L, unmutated IGHV, 11q deletion, 17p deletion, TP53(mut), and SF3B1(mut) on progression-free survival; and for FCR, age ≥65 years, Eastern Cooperative Oncology Group performance status ≥1, β2-microglobulin ≥3.5 mg/L, TK ≥10 U/L, unmutated IGHV, 17p deletion, and TP53(mut) on overall survival. Notably, predictive marker analysis identified an interaction of NOTCH1 mutational status and treatment in that rituximab failed to improve response and survival in patients with NOTCH1(mut). In conclusion, TP53 and SF3B1 mutations appear among the strongest prognostic markers in CLL patients receiving current-standard first-line therapy. NOTCH1(mut) was identified as a predictive marker for decreased benefit from the addition of rituximab to FC. This study is registered at www.clinicaltrials.gov as #NCT00281918.

PURPOSE: To determine the clinical significance of flow cytometric minimal residual disease (MRD) quantification in chronic lymphocytic leukemia (CLL) in addition to pretherapeutic risk factors and to compare the prognostic impact of MRD between the arms of the German CLL Study Group CLL8 trial. PATIENTS AND METHODS: MRD levels were prospectively quantified in 1,775 blood and bone marrow samples from 493 patients randomly assigned to receive fludarabine and cyclophosphamide (FC) or FC plus rituximab (FCR). Patients were categorized by MRD into low- (< 10(-4)), intermediate- (≥ 10(-4) to <10(-2)), and high-level (≥ 10(-2)) groups. RESULTS: Low MRD levels during and after therapy were associated with longer progression-free survival (PFS) and overall survival (OS; P < .0001). Median PFS is estimated at 68.7, 40.5, and 15.4 months for low, intermediate, and high MRD levels, respectively, when assessed 2 months after therapy. Compared with patients with low MRD, greater risks of disease progression were associated with intermediate and high MRD levels (hazard ratios, 2.49 and 14.7, respectively; both P < .0001). Median OS was 48.4 months in patients with high MRD and was not reached for lower MRD levels. MRD remained predictive for OS and PFS in multivariate analyses that included the most important pretherapeutic risk markers in CLL. PFS and OS did not differ between treatment arms within each MRD category. However, FCR induced low MRD levels more frequently than FC. CONCLUSION: MRD levels independently predict OS and PFS in CLL. Therefore, MRD quantification might serve as a surrogate marker to assess treatment efficacy in randomized trials before clinical end points can be evaluated.

Purpose To determine the value of minimal residual disease (MRD) assessments, together with the evaluation of clinical response in chronic lymphocytic leukemia according to the 2008 International Workshop on Chronic Lymphocytic Leukemia criteria. Patients and Methods Progression-free survival (PFS) and overall survival of 554 patients from two randomized trials of the German CLL Study Group (CLL8: fludarabine and cyclophosphamide [FC] v FC plus rituximab; CLL10: FC plus rituximab v bendamustine plus rituximab) were analyzed according to MRD assessed in peripheral blood at a threshold of 10 −4 and clinical response. The prognostic value of different parameters defining a partial response (PR) was further investigated. Results Patients with MRD-negative complete remission (CR), MRD-negative PR, MRD-positive CR, and MRD-positive PR experienced a median PFS from a landmark at end of treatment of 61 months, 54 months, 35 months, and 21 months, respectively. PFS did not differ significantly between MRD-negative CR and MRD-negative PR; however, PFS was longer for MRD-negative PR than for MRD-positive CR ( P = .048) and for MRD-positive CR compared with MRD-positive PR ( P = .002). Compared with MRD-negative CR, only patients with MRD-positive PR had a significantly shorter overall survival (not reached v 72 months; P = .001), whereas there was no detectable difference for patients with MRD-negative PR or MRD-positive CR ( P = 0.612 and P = 0.853, respectively). Patients with MRD-negative PR who presented with residual splenomegaly had only a similar PFS (63 months) compared with patients with MRD-negative CR (61 months; P = .354), whereas patients with MRD-negative PR with lymphadenopathy showed a shorter PFS (31 months; P &lt; .001). Conclusion MRD quantification allows for improved PFS prediction in both patients who achive PR and CR, which thus supports its application in all responders. In contrast to residual lymphadenopathy, persisting splenomegaly does not impact outcome in patients with MRD-negative PR.