EORTC/ASCO guidelines recommend primary prophylaxis (PP) with granulocyte colony stimulating factor (G-CSF) when the risk of chemotherapy (CT)-induced febrile neutropenia (FN) is ≥20%. Without G-CSF prophylaxis, FN risk in patients with non-Hodgkin's lymphoma (NHL) receiving CHOP is up to 50%, and over 50% of FN occurs in cycle 1. Physicians often delay/reduce dose to manage neutropenia, potentially compromising CT efficacy.We identified 3 prospective clinical trials that assessed PP of neutropenia with pegfilgrastim (Neulasta®) 6 mg once per cycle in NHL patients receiving CHOP or CHOP-like regimens ± rituximab. In a retrospective integrated analysis, data from the 3 trials were combined to evaluate the efficacy and safety of PP with pegfilgrastim in a large NHL population. The primary outcome measure was the proportion of patients developing FN.In all, 280 patients started the first cycle of CT, of whom 275 (98%) received pegfilgrastim as PP and were included in the present analyses. The proportion of patients experiencing FN over all cycles was relatively low (15%), and approximately half of FN cases occurred during cycle 1 (Table). WHO grade 3/4 hematological toxicities occurred in the following proportions of patients: white blood cell count (WBC) <2.0×109/L, 63%; absolute neutrophil count (ANC) <1.0×109/L, 67%; hemoglobin <8.0 g/dL, 8%; and platelets <50×109/L, 21%. Grade 4 WBC <1.0×109/L and ANC <0.5×109/L were observed in 39% and 55% of patients. Fifteen percent of patients were hospitalized due to a neutropenic event and 11% were hospitalized due to FN. Anti-infectives were prescribed for 59% of patients. Across all CT cycles, relative dose intensity (RDI) ≥85% was achieved by 88% of patients and RDI ≥90% by 83% of patients. Pegfilgrastim was also effective as PP against FN in the subgroup aged ≥65 years (n=167), who are more susceptible to neutropenia. FN occurred in 17% of these patients (vs 12% of those aged <65 years). Hospitalization due to neutropenic events and FN occurred in 19% and 14% of patients ≥65 years old compared with 9% and 6% of those aged <65 years.To conclude, in this population, PP of FN with pegfilgrastim was associated with a relatively low occurrence of FN (15%) and a high proportion of patients achieving RDI ≥90%. These data support the use of pegfilgrastim 6 mg as PP against FN and neutropenic complications in NHL patients receiving CHOP-like CT, particularly the elderly for whom risk of FN and hospitalization is greatest. These findings support current ASCO/EORTC guideline recommendations.Patients starting each cycle, n (%)Patients with, n (%) [95% CI]FNRDI ≥90%Cycle 1275 (100)20 (7) [4, 10]250 (91) [88, 94]Cycle 2259 (94)7 (3) [1, 5]225 (87) [83, 91]Cycle 3244 (89)7 (3) [1, 5]202 (83) [78, 88]Cycle 4221 (80)8 (4) [1, 6]174 (79) [73, 84]Cycle 5173 (63)2 (1) [0, 3]132 (76) [70, 83]Cycle 6158 (57)5 (3) [0, 6]132 (84) [78, 89]Cycle 7*23 (13)018 (78) [61, 95]Cycle 8*19 (11)015 (79) [61, 97]All cycles275 (100)41 (15) [11, 19]228 (83) [78, 87]*Data from one study only