P927: CLINICAL CHARACTERISTICS, SURVIVAL OUTCOMES AND PROGNOSIS IN 123 IMMUNOGLOBULIN D MULTIPLE MYELOMA PATIENTS: A RETROSPECTIVE SINGLE-CENTER

Field: Medicine (Health Sciences)

Background: Immunoglobulin D (IgD) myeloma is a rare subtype of multiple myeloma (MM), and has been considered to have a more aggressive course and poor outcome. With the rapid progress of multiple myeloma treatment, including the application of proteasome inhibitors and immunomodulatory drugs and the promotion of autologous stem cell transplantation (ASCT), the prognosis of MM patients has been greatly improved. Considering the development of MM treatment, the survival outcome and prognostic factors of IgD MM patients are now controversial. Aims: To evaluate the clinical characteristics, survival outcomes and prognosis of IgD myeloma patients in the era of novel therapy. Methods: We retrospectively analyzed the clinical characteristics of 123 IgD MM patients and compared them with other MM subtypes. At the same time, we also discussed the survival outcomes and prognostic factors of IgD myeloma patients under different treatment modes. Results: Male to female ratio was 2.2, median age was 55 years (29-79 years)， with preponderance of lambda light chains (89.4%). IgD myeloma more likely presented advanced stage when diagnosed: higher frequencies of ISS stage Ⅲ, R-ISS stage Ⅲ, renal dysfunction, high lactate dehydrogenase (LDH) level, high β2MG level and high bone marrow plasmacytosis. Additionally, the genetics of IgD myeloma patients were also different from other subtypes myeloma. Complex karyotypes were more common in IgD myeloma patients (23.9% vs. 14.8%, p=0.017). Cytogenetic abnormalities demonstrated by FISH could be found in 86% (80/93) of the IgD myeloma patients. The frequencies of t (11;14) (38.6% vs. 13.6%, p=0.000) and 1q21 amplification (72.0% vs. 53.9%, p=0.001) were much higher in IgD MM patients than other subtypes myeloma, while deletion of 13q (34.4% vs. 45.7%, p=0.032) and high risk cytogenetic abnormalities (HRCA) (23.0% vs. 37.9%, p=0.009) were less. 71 IgD MM patients received induction therapy based on ‘novel therapies’, 26 on ‘traditional therapies’. Compared with ‘traditional therapies’, ‘novel therapies’ significantly improved the prognosis of IgD patients (PFS 16.9 vs. 29.1 months, P=0.008; OS 37.6 vs. 70.8 months, P=0.002). Further analysis of the ‘novel therapies’ group found that, in non-transplant patients, the prognosis of the IgD and non-IgD patients was similar, but in transplant patients, IgD MM patients showed worse outcomes compared to non-IgD MM patients (figure). Multivariate analysis of 71 IgD patients who received ‘novel therapies’ identified that R-ISS stage Ⅲ, complex karyotypes and deletion of 13q were independent adverse factors for OS, whereas complex karyotypes and thrombocytopenia were independent adverse factors for PFS. Image:Summary/Conclusion: In summary, our study compared the clinical characteristics of IgD and non-IgD MM patients, IgD myeloma patients are younger, have higher tumor burden and advanced disease stage. In addition, their genetics are significantly different from non-IgD MM: IgD MM patients have more complex karyotypes, amplification of 1q21 and t (11;14), while less deletion of 13q and HRCA. Meanwhile, we found that although new drugs combined with ASCT significantly improved the prognosis of MM patients, the improvement of IgD MM is less obvious than that of non-IgD MM patients, suggesting more targeted drugs need to be developed for patients with IgD MM. Finally, we identified that R-ISS stage Ⅲ, complex karyotypes and deletion of 13q were independent adverse factors for OS, indicating that R-ISS is still useful way to predict the outcomes of patients with IgD myeloma.