Background: Multiple myeloma (MM) is a major health concern. Understanding the different burden and tendency of MM in different regions is crucial for formulating specific local strategies. Therefore, we evaluated the epidemiologic patterns and explored the risk factors for MM death. Methods: Data on MM were collected from the 2019 Global Burden of Disease study. We used incidence, mortality, and disability adjusted life-years to estimate the global, regional, and national burden of MM. Results: In 2019, there were 155,688 (95% UI, 136,585 – 172,577) MM cases worldwide, of which 84,516 (54.3%, 70,924 – 94,910) were of men. The age-standardized incidence rate (ASIR) was 1.72/100,000 persons (95% UI, 1.59–1.93) in 1990 and 1.92/100,000 persons (95% UI, 1.68–2.12) in 2019. The number of MM deaths increased 1.19-fold from 51,862 (95% UI, 47,710–58,979) in 1990 to 113,474 (95% UI, 99,527 – 121,735) in 2019; the age-standardized death rate (ASDR) was 1.42/100,000 persons (95% UI, 1.24–1.52) in 2019. In recent 15 years, ASDR showed a steady tendency for men, and a downward tendency for women. Countries with high social-demographic indexes exhibited a higher ASIR and ASDR. Australasia, North America, and Western Europe had the highest ASIR and ASDR, with 46.3% incident cases and 41.8% death cases. Monaco had the highest ASIR and ASDR, which was almost half as high as the second highest country Barbados. In addition, United Arab Emirates and Qatar had the largest growth multiple in ASIR and ASDR, which was twice the third country Djibouti. Conclusions: Globally, incident and death MM cases have more than doubled over the past 30 years. The increasing global burden may continue with population aging, whereas mortality may continue to decrease with the progression of medical technology. The global burden pattern of MM was diverse, therefore specific local strategies based on different burden patterns for MM are necessary.

Chimeric antigen receptor-modified (CAR) T cells targeting CD19 (CART19) have shown therapeutical activities in CD19+ malignancies. However, the etiological nature of neurologic complications remains a conundrum. In our study, the evidence of blood-brain barrier (BBB)-penetrating CAR T cells as a culprit was revealed. A patient with acute lymphocytic leukemia developed sustained pyrexia with tremors about 6 h after CART19 infusion, followed by a grade 2 cytokine release syndrome (CRS) and neurological symptoms in the next 3 days. Contrast-enhanced magnetic resonance showed signs of intracranial edema. Lumbar puncture on day 5 showed an over 400-mmH2O cerebrospinal pressure. The cerebrospinal fluid (CSF) contained 20 WBCs/μL with predominant CD3+ T cells. qPCR analysis for CAR constructs showed 3,032,265 copies/μg DNA in CSF and 988,747 copies/μg DNA in blood. Cytokine levels including IFN-γ and IL-6 in CSF were extremely higher than those in the serum. Methyprednisone was administrated and the symptoms relieved gradually. The predominance of CART19 in CSF and the huge discrepancies in cytokine distributions indicated the development of a cerebral CRS, presumably featured as CSF cytokines largely in situ produced by BBB-penetrating CAR T cells. For the first time, we reported the development of cerebral CRS triggered by BBB-penetrating CAR T cells. Trial registration: ChiCTR-OCC-15007008 .

Background: Consolidative allogeneic hematopoietic stem cell transplantation is a controversial option for patients with relapsed/refractory acute lymphoblastic leukemia after chimeric antigen receptor T cell (CAR-T) therapy. We performed a multicenter retrospective study to assess whether patients can benefit from haploidentical hematopoietic stem cell transplantation after CAR-T therapy. Methods: A total of 122 patients after CAR-T therapy were enrolled, including 67 patients without subsequent transplantation (non-transplant group) and 55 patients with subsequent haploidentical hematopoietic stem cell transplantation (transplant group). Long-term outcome was assessed, as was its association with baseline patient characteristics. Results: Compared with the non-transplant group, transplantation recipients had a higher 2-year overall survival (OS; 77.0% versus 36.4%; P < 0.001) and leukemia-free survival (LFS; 65.6% versus 32.8%; P < 0.001). Multivariate analysis showed that minimal residual disease (MRD) positivity at transplantation is an independent factor associated with poor LFS (P = 0.005), OS (P = 0.035), and high cumulative incidence rate of relapse (P = 0.045). Pre-transplant MRD-negative recipients (MRD− group) had a lower cumulative incidence of relapse (17.3%) than those in the non-transplant group (67.2%; P < 0.001) and pre-transplant MRD-positive recipients (MRD+ group) (65.8%; P = 0.006). The cumulative incidence of relapse in MRD+ and non-transplant groups did not differ significantly (P = 0.139). The 2-year LFS in the non-transplant, MRD+, and MRD− groups was 32.8%, 27.6%, and 76.1%, respectively. The MRD− group had a higher LFS than the non-transplantation group (P < 0.001) and MRD+ group (P = 0.007), whereas the LFS in the MRD+ and non-transplant groups did not differ significantly (P = 0.305). The 2-year OS of the MRD− group was higher than that of the non-transplant group (83.3% versus 36.4%; P < 0.001) but did not differ from that of the MRD+ group (83.3% versus 62.7%; P = 0.069). The OS in the non-transplant and MRD+ groups did not differ significantly (P = 0.231). Conclusion: Haploidentical hematopoietic stem cell transplantation with pre-transplant MRD negativity after CAR-T therapy could greatly improve LFS and OS in patients with relapsed/refractory acute lymphoblastic leukemia. Trial registration: The study was registered in the Chinese clinical trial registry (ChiCTR1900023957).

Chimeric antigen receptor T‐cell (CAR‐T) treatment has revolutionized the landscape of cancer therapy with significant efficacy on hematologic malignancy, especially in relapsed and refractory B cell malignancies. However, unexpected serious toxicities such as cytokine release syndrome (CRS) and immune effector cell‐associated neurotoxicity syndrome (ICANS) still hamper its broad application. Clinical trials using CAR‐T cells targeting specific antigens on tumor cell surface have provided valuable information about the characteristics of ICANS. With unclear mechanism of ICANS after CAR‐T treatment, unremitting efforts have been devoted to further exploration. Clinical findings from patients with ICANS strongly indicated existence of overactivated peripheral immune response followed by endothelial activation‐induced blood–brain barrier (BBB) dysfunction, which triggers subsequent central nervous system (CNS) inflammation and neurotoxicity. Several animal models have been built but failed to fully replicate the whole spectrum of ICANS in human. Hopefully, novel and powerful technologies like single‐cell analysis may help decipher the precise cellular response within CNS from a different perspective when ICANS happens. Moreover, multidisciplinary cooperation among the subjects of immunology, hematology, and neurology will facilitate better understanding about the complex immune interaction between the peripheral, protective barriers, and CNS in ICANS. This review elaborates recent findings about ICANS after CAR‐T treatment from bed to bench, and discusses the potential cellular and molecular mechanisms that may promote effective management in the future.This article is categorized under: Cancer > Biomedical Engineering Immune System Diseases > Molecular and Cellular Physiology Neurological Diseases > Molecular and Cellular Physiology