Plasma Host-Microbe Proteomics to Predict Complications in High-risk Febrile Neutropenia

Febrile neutropenia (FN) is a common oncologic emergency in patients with hematologic malignancies, associated with high morbidity and mortality. Early identification of patients at higher risk of complications such as sepsis or septic shock is critical to optimize antimicrobial management. This study aims to characterize the human and microbial plasma proteome using high-resolution mass spectrometry to identify biomarker combinations ("combitypes") capable of predicting complications in oncohematologic patients with FN. A cohort of 350 adult patients with high-risk FN and initially uncomplicated clinical presentation will be enrolled across three tertiary hospitals. Plasma samples will be collected at fever onset (before antibiotic initiation) and after 48 hours. Proteomic data will be integrated with clinical information using multivariate and machine learning models to develop a predictive model for complications.

Inclusion Criteria: * Adults (≥18 years). * Written informed consent provided by patient or legal representative. * Diagnosis of hematologic malignancy under induction chemotherapy, post-allogeneic hematopoietic stem cell transplantation, or CAR-T therapy. * High-risk febrile neutropenia (ANC ≤ 100 cells/mm³, expected duration ≥ 7 days, or significant comorbidities). * Fever defined as oral temperature ≥38.3 °C once or ≥38.0 °C for ≥1 hour. * Hospitalized or requiring immediate admission at the time of FN diagnosis. ´- Initial uncomplicated clinical presentation, with no previous infection or colonization by multidrug-resistant bacteria. * Eligible for initial monotherapy with broad-spectrum empirical antibiotic. * Availability for serial plasma sampling and clinical follow-up. Exclusion Criteria: * Age \