Identification of New Antibodies Targeting Malignant Plasma Cells for Immunotherapy by Next-Generation Sequencing-Assisted Phage Display

To identify new antibodies for the treatment of plasma cell disorders including multiple myeloma (MM), a single-chain Fragment variable (scFv) antibody library was generated by immunizing mice with patient-derived malignant plasma cells. To enrich antibodies binding myeloma antigens, phage display with cellular panning was performed. After depleting the immune library with leukocytes of healthy donors, selection of antibodies was done with L-363 plasma cell line in two consecutive panning rounds. Monitoring the antibodies’ enrichment throughout the panning by next-generation sequencing (NGS) identified several promising candidates. Initially, 41 unique scFv antibodies evolving from different B cell clones were selected. Nine of these antibodies strongly binding to myeloma cells and weakly binding to peripheral blood mononuclear cells (PBMC) were characterized. Using stably transfected Chinese hamster ovary cells expressing individual myeloma-associated antigens revealed that two antibodies bind CD38 and intercellular adhesion molecule-1 (ICAM-1), respectively, and 7 antibodies target yet unknown antigens. To evaluate the therapeutic potential of our new antibodies, in a first proof-of-concept study the CD38 binding scFv phage antibody was converted into a chimeric IgG1. Further analyses revealed that #5-CD38-IgG1 shared an overlapping epitope with daratumumab and isatuximab and had potent anti-myeloma activity comparable to the two clinically approved CD38 antibodies. These results indicate that by phage display and deep sequencing, new antibodies with therapeutic potential for MM immunotherapy can be identified.

Real-world data on survival improvement in patients with multiple myeloma treated at a single institution over a 45-year period

The prognostic landscape of multiple myeloma (MM) has evolved significantly over the last few decades. There are, however, few data measuring such improvement in real-world patients. This study aimed to investigate trends in survival improvement over 45 years, and the associated clinical factors, in an unselected population of patients with MM. Between 1970 and 2015, 1 161 MM patients were included. Patients were classified into three calendar periods (1970-1984, 1985-1999, and 2000-2015), according to the treatment received; polychemotherapy, autologous stem cell transplantation, and novel drugs respectively. We analysed relative survival (RS) to accurately evaluate MM-related death rates after excluding the mortality expected in the general population. RS at five years increased from 27% in 1970-1984 to 38% and 56% in the next two calendar periods respectively. The improvement to survival was greater in the younger population, but it was also observed in elderly patients and those with poor performance status and more advanced disease. Although myeloma is still a non-curable disease, encouraging results have been observed in the last decades. Progress is expected to continue with the use of new generations of anti-myeloma drugs, and will, hopefully, be documented in real-world patients by the appropriate population-based studies.