Background: Thrombotic microangiopathy (TMA) is a potentially life-threatening complication associated with carfilzomib, a proteasome inhibitor approved for treating multiple myeloma. TMA typically presents within the initial months of treatment; however, delayed onset is rare and poses significant diagnostic challenges. Methods: We conducted a retrospective analysis of the medical records of a 47-year-old Caucasian woman diagnosed with IgA kappa myeloma who developed signs and symptoms consistent with TMA eleven months after the initiation of carfilzomib therapy and already in ongoing very good partial remission. Results: The clinical presentation included an acute onset of weakness, dizziness, somnolence, diffuse bruising, oliguria, jaundice, severe thrombocytopenia, and acute kidney injury. An immediate workup raised a strong suspicion for TMA, confirmed by laboratory findings of schistocytosis and complement activation. Following the immediate discontinuation of carfilzomib, the patient underwent 18 plasmapheresis (PEX) sessions and received supportive fresh frozen plasma transfusions, which resulted in the complete remission of TMA symptoms without the need for complement inhibitory therapy. Conclusions: The need for ongoing monitoring for TMA throughout carfilzomib therapy, regardless of treatment duration, is emphasized. Early diagnosis and intervention, including drug discontinuation and the timely initiation of PEX, are crucial for patient recovery.

Background: The optimal approach for adult patients hospitalized with severe and critical coronavirus disease 2019 (COVID-19), non-responsive to antiviral and immunomodulatory drugs, is not well established. Our aim was to evaluate feasibility and safety of extracorporeal photopheresis (ECP) in this setting. Methods: A prospective, single-center investigational study was performed between 2021 and 2022 at a tertiary referral center for COVID-19. Patients diagnosed with COVID-19 were screened, and cases with severe or critical disease fulfilling pre-defined clinical and biochemical criteria of non-response for >5 days, despite remdesivir, dexamethasone and immunomodulation (tocilizumab, baricitinib, ruxolitinib), were consecutively enrolled. After patient inclusion, two ECP sessions on two consecutive days per week for 2 weeks were applied. Patients were followed-up per protocol from study inclusion, and clinical, virological and radiological outcomes were assessed at the end of treatment (EOT) +28 days. Results: A total of seven patients were enrolled. At inclusion, four out of seven (57.1%) were admitted to the ICU, all patients had ongoing cytokine storm. Additionally, 3/7 (42.9%) had radiological progression on chest CT. At EOT+28 days, 2/7 (28.6%) patients died due to non-ECP-related causes. Among the survivors, no additional requirement for intensive care unit admission or radiological progression was observed, and invasive mechanical ventilation could be weaned off in 1/5 (20.0%). All patients achieved whole-blood SARS-CoV-2 RNAemia clearance, while 3/7 (42.9%) no longer showed detectable respiratory SARS-CoV-2 RNA. According to immune biomarker profiling, ECP mainly facilitated a decrease in plasma IL-6 and IL-17A levels, as well as the physiological regeneration of peripheral blood immunocyte subpopulations, notably CD8+/CD45RO+ memory T-cells. No safety signals were identified. Conclusions: ECP appears to be a safe and feasible option for adults hospitalized with severe or critical COVID-19 who do not respond to pharmacological interventions. Further trial data are warranted to assess its optimal use. Trial registration: ClinicalTrials.gov NCT05882331 (retrospectively registered).