Impact of Different Chemotherapy Regimen in Comorbid Patients with Advanced Chronic Lymphocytic Leukemia: Metaanalysis of Two Phase-III-Trials of the German CLL Study Group.

Introduction: Since chronic lymphocytic leukemia (CLL) is a disease of elderly patients (pts) comorbidity is a frequent feature which has already been shown to be associated with survival-shortening in lymphoma patients. It has been hypothesized that intensity of chemotherapy may interfere with treatment outcome, but the precise mechanisms underlying the impact of comorbidity are still not understood. Consequently, comorbitity currently keeps away oncologists from administering intense combined (immuno−)chemotherapy to pts with CLL and concomitant diseases.

Patients & methods: 554 pts treated in two different phase-III-trials of the GCLLSG were eligible for this analysis: 362 pts (65%) younger than 65 years were treated on the CLL4-protocol with Fludarabine (F) or Fludarabine-Cyclophosphamide (FC) and 192 pts (35%) aged 65 years and older on the CLL5-protocol with F or Chlorambucile (Clb). The mean age for all pts was 61 years; 68% of the pts were male.

Results: Comorbidity was present in 53% of the pts, 25% had at least two comorbidities. The most common comorbidities were: hypertension (19%), lipometabolic disorders (16%), diabetes mellitus (10%) and coronary heart disease (7%).

Progression free survival (PFS) and overall survival (OS) were significantly shorter in comorbid pts (median OS: 43,5 vs. 51,6 months, p=0,01; median PFS: 20,3 vs. 23,5 months, p=0,03). Survival was also impaired if pts had a higher number of comorbidities (PFS & OS: p=0,0001) or more severe concomitant diseases (PFS: p=0,007, OS: p=0,0000).

Whereas this impact of comorbidity on OS was not significant in the FC- and Clb-arm, comorbid pts treated with F had a significantly shorter survival (median OS: 38,29 vs. 51,58 months, p=0,0452). Notably only the younger F-treated comorbid pts were affected by this disadvantage (CLL4: p=0,0221).

Although myelotoxicity, infections and all grade III–IV adverse effects were not influenced by comorbidity, pts with concomitant disease had a higher rate of treatment terminations (38% vs. 25%, p=0,002). The higher percentage of dose reductions and treatment terminations for comorbid pts were only significant in the subgroup of F-treated pts (dose reduction: 31% vs. 19,1%, p=0,029; treatment termination in the younger CLL4-pts: 28,2% vs. 18,0%, p=0,023).

Administration of more intense chemotherapy-regimen improved the survival of pts with concomitant disease (median OS: FC: not reached, F: 38,29 and Clb: 33,72 months, p=0,0248; median PFS: FC: not reached, F: 18,8 and Clb: 14,1 months, p=0,0000). A multivariate analysis on the prognostic impact of comorbidity and different chemotherapy regimen will be presented.

Conclusions: Due to the here presented results the wide impact of comorbidity in CLL pts is apparent. It should be considered when it comes to treatment decisions eventhough this population was selected due to the strict criteria of the clinical trial. The mechanism of survival shortening in comorbid pts with CLL is not yet understood, but seems to be related with dose reductions and treatment terminations. Additional harm to these pts by an insufficient treatment and a poor control of the CLL ought to be avoided.

As more intense chemotherapy-regimen, like FC are feasible for pts with comorbidity, more trials surveying these therapies in pts with more severe concomitant disease are needed.