Extracellular Vesicles Isolated from Plasma of Multiple Myeloma Patients Treated with Daratumumab Express CD38, PD-L1, and the Complement Inhibitory Proteins CD55 and CD59.

Daratumumab (DARA) has improved the outcome of treatment of multiple myeloma (MM). DARA acts via complement-dependent and -independent mechanisms. Resistance to DARA may result from upregulation of the complement inhibitory proteins CD55 and CD59, downregulation of the DARA target CD38 on myeloma cells or altered expression of the checkpoint inhibitor ligand programmed death ligand-1 (PD-L1) or other mechanisms. In this study, EVs were isolated from peripheral blood (PB) and bone marrow (BM) from multiple myeloma (MM) patients treated with DARA and PB of healthy controls. EV size and number and the expression of CD38, CD55, CD59 and PD-L1 as well as the EV markers CD9, CD63, CD81, CD147 were determined by flow cytometry. Results reveal that all patient EV samples express CD38, PD-L1, CD55 and CD59. The level of CD55 and CD59 are elevated on MM PB EVs compared with healthy controls, and the level of PD-L1 on MM PB EVs is higher in patients responding to treatment with DARA. CD147, a marker of various aspects of malignant behaviour of cancer cells and a potential target for therapy, was significantly elevated on MM EVs compared with healthy controls. Furthermore, mass spectrometry data suggests that MM PB EVs bind DARA. This study reveals a MM PB and BM EV protein signature that may have diagnostic and prognostic value.

Clinically-suspected cast nephropathy: A retrospective, national, real-world study.

Presentation with severe acute kidney injury due to cast nephropathy (CN) is a medical emergency in multiple myeloma (MM), with high risk of dialysis-dependent renal failure and death. Accrual of patients with CN into interventional studies is difficult, while phase III trials exclude patients with severe renal insufficiency. Real-world data are warranted. We assessed 2252 patients from the population-based Danish Multiple Myeloma Registry (DMMR) who were diagnosed between 2013 and 2017. We identified 204 patients with clinically-suspected CN, defined as serum creatinine concentration >177 µmol/L and serum free light chain (sFLC) concentration >1000 mg/L at the time of diagnosis. The median age was 72 years. Thirty-one percent of patients presented with dialysis-dependent renal failure. Kidney biopsies were performed in 19% of patients and showed CN in 74% of cases. Despite prompt initiation of bortezomib-based therapy in 94% of patients, 33% of patients died in the first year after diagnosis. Compared with the rest of the patients in the DMMR with symptomatic MM, patients with clinically-suspected CN had worse overall survival (OS) irrespective of transplant eligibility. Achievement of renal recovery was associated with deep reductions of involved sFLC. Achievement of very good partial response or better in the first line of therapy and/or deep reduction of involved sFLC at 3 months after initiation of therapy were associated with superior OS. In conclusion, MM patients presenting with clinically-suspected CN have an alarmingly high one-year mortality when treated with current standards of care. Early and deep hematologic response is crucial for survival.

Long term molecular responses in a cohort of Danish patients with essential thrombocythemia, polycythemia vera and myelofibrosis treated with recombinant interferon alpha.

Within recent years data has accumulated demonstrating the efficacy of recombinant interferon alpha2 (rIFN-alpha2) in the treatment of chronic myeloproliferative neoplasms (MPNs). We report on clinical and molecular data in the largest cohort of JAK2 V617F mutant MPN Danish patients (n=102) being treated long-term with rIFN-alpha2 (rIFN-alpha2a and rIFN-alpha2b in a non-clinical trial setting. The median follow-up was 42 months. We substantiate the capacity of rIFN-alpha2 to induce complete hematologic remissions (ET 95%, PV 68%) and molecular response. In total 76 patients (74.5%) had a decline in JAK2 V617F allele burden with a median reduction from baseline of 59% (95% c.i. 50-73%, range 3-99%). A decline in JAK2 V617F allele burden was recorded in both ET (median 24-10% (95% c.i.: 8-16%), and PV (median 59-35% (95% c.i.: 17-33%). Patients with the lowest pre-treatment JAK2 V617F allele burdens tend to achieve the most favourable responses on long term treatment with rIFN-alpha2. Eleven patients (10%) had deep molecular remissions with ≤ 2% JAK2 V617F mutant DNA. Finally, long term treatment with rIFN-alpha2 was associated with a very low thrombosis rate. Our observations are supportive of the concept of early up-front treatment with rIFN-alpha2.