Safety and efficacy of mecapegfilgrastim in preventing neutropenia in patients with head and neck cancer: a multicenter, prospective, observational, real-world study

Background: Mecapegfilgrastim, a long-acting granulocyte colony-stimulating factor, is approved in China for neutropenia prevention. However, data on its safety and efficacy in patients with head and neck cancer remain limited. This study aimed to evaluate the safety and efficacy of mecapegfilgrastim in preventing neutropenia among these patients undergoing chemotherapy, particularly those receiving chemoradiotherapy or chemoimmunotherapy. Methods: This prospective, non-interventional, real-world study enrolled patients aged >= 18 years with pathologically or cytohistologically confirmed head and neck cancer who were deemed tolerable to mecapegfilgrastim. The administration of mecapegfilgrastim was determined by the local physicians. Patients were observed for up to four chemotherapy cycles, with follow-up 30 +/- 2 days post-final administration. The primary outcome was the incidence of adverse events following mecapegfilgrastim administration. Secondary outcomes included the incidence of grade >= 3 and grade 4 neutropenia [defined as absolute neutrophil count (ANC) <1.0x109/L and ANC <0.5x109/L, respectively], febrile neutropenia (FN), and infections across all chemotherapy cycles. Results: Between May 2019 and November 2021, 197 patients were enrolled from 24 sites across China. The median age was 53 years, and 76.6% were male. Among them, 25.9% underwent chemoradiotherapy and 38.6% received chemoimmunotherapy. Treatment-related adverse events (TRAEs) of any grade occurred in 18 (9.1%) of all patients, 6 (11.8%) of the 51 patients who underwent chemoradiotherapy, and 4 (5.3%) of the 76 patients who received chemoimmunotherapy. The most common TRAEs of any grade were increased (n=10, 5.1%) and decreased (n=5, 2.5%) white blood cell count. When mecapegfilgrastim was administered prophylactically during the initial chemotherapy cycle, grade >= 3 neutropenia occurred in 5.1% of 178 cycles with combined immunotherapy and 6.4% of 267 cycles without immunotherapy. No FN cases were observed in the immunotherapy group. Among 119 cycles with radiotherapy, grade >= 3 neutropenia occurred in 5.0%, compared to 6.1% in the 326 cycles without radiotherapy, with one FN case reported. Across 445 chemotherapy cycles with prophylactic mecapegfilgrastim, grade >= 3 neutropenia occurred in 26 cycles (5.8%), grade 4 neutropenia in 16 cycles (3.6%), FN in 1 cycle (0.2%), and infections in 7 cycles (1.6%). Conclusions: Mecapegfilgrastim demonstrated promising efficacy and safety in preventing neutropenia in patients with head and neck cancer, particularly those undergoing chemoradiotherapy or chemoimmunotherapy. Mecapegfilgrastim was well tolerated, with no new safety signals identified. These real-world findings support its continued use for neutropenia prevention in patients with head and neck cancer.