Can we predict chemo-induced hematotoxicity in elderly patients treated with pegylated liposomal doxorubicin? Results of a population-based model derived from the DOGMES phase II trial of the GINECO

IntroductionUse of anthracyclines is often limited in older patients due to cardiac and hematologic toxicities. Thanks to its reduced toxicity profile, Pegylated Liposomal Doxorubicin (PLD) allows an extended use of doxorubicin to this population. We aimed at modeling PLD-induced hematotoxicity in patients with metastatic breast cancer ≥ 70 years old and at finding predictive factors of neutrophil nadir value.MethodsSixty patients, enrolled in the DOGMES prospective multicentric phase II trial, were treated with PLD at 40 mg/m2 every 28 days during six cycles. Trial design included geriatric covariates assessment at inclusion and monitoring of cells count every week for three cycles. A population model was developed to describe hematopoiesis and hematopoietic reserve in these patients. The effect of co-administered G-CSF (granulocyte colony-stimulating factor) was also examined.ResultsA pharmacodynamic model was built using data from 53 patients not receiving G-CSF. This model assumed an instantaneous effect of PLD on the system. Based on this model, exact neutrophil nadir value was computed and ranged between 0.069 K/mm3 and 2.63 K/mm3 confirming the weak hematotoxicity of PLD. The same model was then applied to the 7 patients receiving G-CSF and showed that basal neutrophil count was higher for these patients. No other difference was found between both cohorts. Among the covariates collected, three were predictive of neutrophil nadir value: diabetes, frailty syndrome and assistance at home.ConclusionThis developed model allowed the identification of predictive factors of nadir ANC and the identification of patients that are more likely to develop hematotoxicity that should be monitored with attention.