3-Hydroxy-Kyurenine [BSA]

Anemia often coincides with depression and impaired quality of life (QoL) in cancer patients. Sustained immune activation can lead to the development of anemia. Furthermore, it also may go along with changes in tryptophan and phenylalanine metabolism. The aim of our pilot study was to study the relationship between anemia, immune-mediated changes in amino acid metabolism, and the QoL and mood of cancer patients. Questionnaires to measure QoL and depression were completed by 152 patients with solid tumors. Hemoglobin, parameters of immune activation as well as tryptophan and phenylalanine metabolism were determined in the patients' sera. Anemic patients (51.7%) presented with higher inflammatory markers, and a higher tryptophan breakdown with lower tryptophan concentrations. They reported an impaired QoL and had higher depression scores. Patients with an impaired QoL (65.8%) also suffered from more fatigue and impaired physical, emotional, and social functioning. They, furthermore, presented with higher concentrations of inflammatory markers (C-reactive protein (CRP) and neopterin) as well as higher tryptophan degradation (in men) and higher phenylalanine concentrations (in women). Sixty-one patients (40.1%) had (mostly mild) depression. In these patients, a higher degree of Th1 immune activation was found. The results of our study suggest that cancer-related anemia goes along with an impaired QoL, which is also associated with immune-mediated disturbances of tryptophan and phenylalanine metabolism.

An option currently being explored for the treatment of COVID-19 is the use of interferons (INFs), either alone or in combination with other antiviral agents. INFs are known to shift the metabolism of tryptophan (TRP) away from its role as a precursor of serotonin. For some patients, reduction in TRP levels may either expose an underlying vulnerability to depression or trigger a de novo episode of depression. This Commentary discusses the pathway involved and recommends in-hospital augmentation with foods or supplements that increase TRP levels for COVID-19 patients treated with INFs. Selective serotonin reuptake inhibitors may also be tried if the depressive symptomatology is not short-lived.