Discussion
BIPN, neuropathy, axonal damage, neurotoxic, Neurotoxicity
MYELOMA, DISEASE, NEUROPATHY
In this cross-sectional analysis, we found that patients with BTZ treatment either at present or in the past had higher serum NfL levels than controls, and that patients with ongoing BTZ treatment had higher NfL levels than patients with BTZ treatment in the past. There was a trend towards an increase in NfL levels across neuropathy severity grades in the OT group, and NfL levels correlated with neurophysiological measures of axonal damage.In this analysis, we included patients with BTZ therapy with and without neuropathy, to first analyze the effect of BTZ on NfL levels in general. In our cohort, more patients had neuropathy than described in the literature; there were only 4 patients in the OT and 3 in the PT group without neuropathy. However, the OT patients were included into the study within the first 5 BTZ cycles. Whether these patients will develop neuropathy later will be the question of a follow-up study, providing longitudinal data, and thus also information on the relation of NfL levels and the course of BIPN.Our clinical findings are in agreement with the disease pattern of BIPN described before [Neurotoxicity in general is often related to the cumulative dose of chemotherapeutic agents [NfL has recently been investigated in patients receiving other neurotoxic agents like vincristine and paclitaxel [Our study has some limitations, first, its cross-sectional design. A longitudinal evaluation will be needed to assess the predictive value of NfL for BIPN. Furthermore, patients received individual therapy regimens in combination with BTZ based on myeloma parameters and the patient's constitution (Suppl. Table 1).The question also arises whether different pathophysiological processes take place in the acute and chronic phases of BIPN: although the PT group was somewhat more severely affected, the patients from this group nevertheless had NfL values that are closer to the control values, the longer the time since the last application. Follow up of patients in whom BIPN does not regress even months to years after discontinuation of BTZ is warranted.In conclusion