Insights into defective serological memory after acute lymphoblastic leukaemia treatment: The role of the plasma cell survival niche, memory B-cells and gut microbiota in vaccine responses

Real-world vaccination status of children with hematologic tumors before and after chemotherapy

BACKGROUND

There is a high incidence and mortality rate in children with hematologic tumors (CHT), who are more prone to various infectious diseases. This study aims to clarify the real-world National Immunization Program (NIP) vaccination status of CHT before and after chemotherapy.

METHODS

Medical records, NIP vaccination data, and the Adverse Event Following Immunization (AEFI) of CHT who were admitted to the Children's Hospital, Zhejiang University School of Medicine from January 1, 2011 to December 1, 2021 were completely collected.

RESULTS

Total of 2,874 CHT were included and 1975 (68.7%) had vaccination records. Among the enrolled patients, the vaccination rate of all NIP vaccines was lower than 90% before diagnosis. Only 24.29% of CHT (410/1688) resumed vaccination after chemotherapy, and 69.02% (283/410) resumed vaccination more than 12 months after chemotherapy. No uncommon or serious side effects were reported.

CONCLUSION

The vaccination rate of CHT after chemotherapy was lower than that before the disease was diagnosed. It is necessary to provide more evidence-based support and formulate specific regimens to perfect the vaccination procedure after chemotherapy, so as to improve the quality of life of CHT.

Mechanisms of Immunosuppressive Tumor Evasion: Focus on Acute Lymphoblastic Leukemia

Acute lymphoblastic leukemia (ALL) is a malignancy with high heterogeneity in its biological features and treatments. Although the overall survival (OS) of patients with ALL has recently improved considerably, owing to the application of conventional chemo-therapeutic agents, approximately 20% of the pediatric cases and 40-50% of the adult patients relapse during and after the treatment period. The potential mechanisms that cause relapse involve clonal evolution, innate and acquired chemoresistance, and the ability of ALL cells to escape the immune-suppressive tumor response. Currently, immunotherapy in combination with conventional treatment is used to enhance the immune response against tumor cells, thereby significantly improving the OS in patients with ALL. Therefore, understanding the mechanisms of immune evasion by leukemia cells could be useful for developing novel therapeutic strategies.

T Cell Subsets During Early Life and Their Implication in the Treatment of Childhood Acute Lymphoblastic Leukemia

The immune system plays a major role in recognizing and eliminating malignant cells, and this has been exploited in the development of immunotherapies aimed at either activating or reactivating the anti-tumor activity of a patient's immune system. A wide range of therapeutic approaches involving T lymphocytes, such as programmed cell death protein ligand-1 (PDL-1) inhibitors, cytotoxic T-lymphocyte-associated protein-4 (CTLA-4) blockers, and CD19-targeted T-cell therapy through chimeric antigen receptor (CAR)-T cells or CD19/CD3 bi-specific T-cell engagers, have been introduced to the field of oncology, leading to significant improvements in overall survival of adult cancer patients. During the past few years, the availability and approval of T-cell based immunotherapies have become a reality also for the treatment of childhood cancers. However, the distribution, ratio of regulatory to effector cells and the quality of T-cell responses early in life are distinct from those during adolescence and adulthood, raising the possibility that these differences impact the efficacy of immunotherapy. Herein we provide a brief overview of the properties of conventional T cell subsets during early life. Focusing on the most common cancer type during childhood, acute lymphoblastic leukemia (ALL), we describe how current conventional therapies used against ALL influence the T-cell compartment of small children. We describe early life T-cell responses in relation to immunotherapies engaging T-cell anticancer reactivity and present our opinion that it is not only immaturity of the adaptive immune system, but also the impact of an immunosuppressive environment that may prove disadvantageous in the setting of immunotherapies targeting pediatric cancer cells.

Impact of chemotherapy on lymphocytes and serological memory in recovered COVID-19 patients with acute leukemia

Chemotherapy is the major method of treatment for acute leukemia to date, while intensive chemotherapy may impair immunity. We previously reported that leukemia patients were more susceptible to COVID-19 than the overall population. However, for COVID-19 recovered patients with leukemia, the impacts of intensive chemotherapy on the immune memory of COVID-19 are unknown. This study characterized the changes in immune cells and SARS-CoV-2 antibodies in acute leukemia patients, who underwent chemotherapy after recovering from COVID-19. The study enrolled three groups of individuals. One group was a total of three acute leukemia patients, who recovered well from COVID-19 before the last cycle of chemotherapy. The other two groups were six COVID-19 recovered healthy people, and six normal uninfected healthy people, respectively. Levels of B cells, T cells, and NK cells in peripheral blood were analyzed by multiparameter flow cytometry. Besides, the SARS-CoV-2 antibodies were monitored. The results showed that B cells were severely decreased after chemotherapy, especially memory B cells. Most of the T cells and NK cells showed only minor changes after chemotherapy, except for γδ T cells. The serum levels of SARS-CoV-2 antibodies were not significantly affected after chemotherapy in two leukemia patients. However, interestingly, one leukemia patient's SARS-CoV-2 IgM showed dramatically increase, suggesting possible loss of serological memory after chemotherapy. These findings raised the concern for the stability of immune memory against SARS-CoV-2 during chemotherapy and the choice of anti-leukemia treatment in the COVID-19 pandemic.

Intestinal Dysbiosis and Development of Cardiometabolic Disorders in Childhood Cancer Survivors: A Critical Review

Significance: Survivors of pediatric cancers have a high risk of developing side effects after the end of their treatments. Many potential factors have been associated with the onset of cardiometabolic disorders (CMD), including cancer disease itself, chemotherapy, hormonal treatment, radiotherapy, and genetics. However, the precise etiology and underlying mechanisms of these long-term complications are poorly understood. Recent Advances: Greater awareness is currently paid to the role of microbiota in the emergence of cancers and modulation of cancer therapies in both children and adults. Alterations in the composition and diversity of intestinal microbiota can clearly influence tumor development and progression as well as immune responses and clinical output. As dysbiosis is closely linked to the development of host metabolic diseases, including obesity, metabolic syndrome, type 2 diabetes, and non-alcoholic fatty liver disease, it may increase the risk of CMD in cancer populations. Critical Issues: Only limited studies targeting the profile of intestinal dysbiosis before and after cancer treatment have been conducted. Further, the exact contribution of intestinal dysbiosis to the development of CMD in cancer survivors is poorly appreciated. This review intends to clarify the influence of gut microbiota on CMD in childhood cancer survivors, elucidate the potential mechanisms, and evaluate the latest research on the interplay between diet/food supplement, microbiota, and cancer-related CMD. Future Directions: The implication of intestinal dysbiosis in late metabolic complications of childhood cancer survivors should be clarified. Intervention strategies could be developed to reduce the risk of survivors to CMD. Antioxid. Redox Signal. 34, 223-251.

Deficits in the IgG+ memory B-cell recovery after anthracycline treatment is confined to the spleen of rhesus macaques

Objectives

Loss of vaccine‐induced antibodies (Abs) after chemotherapy against paediatric acute lymphoblastic leukaemia (ALL) is common and often necessitates re‐immunisation after cessation of treatment. Even so, some ALL survivors fail to mount or to maintain protective Abs. Germinal centres (GCs) are clusters of proliferating B cells in follicles of secondary lymphoid tissues (SLTs) formed during adaptive immune responses and the origins of long‐lived memory B and plasma cells that are the source of Abs. Furthermore, productive GC reactions depend on T follicular helper (T_FH) cells. To understand why chemotherapy induces deficits in Ab responses, we examined how SLTs were affected by chemotherapy.

Methods

Rhesus macaques were infused with either three cycles of the anthracycline doxorubicin or saline, followed by immunisation with a de novo and booster antigen. Spleen and lymph nodes were removed, and memory B, bulk T and T_FH cells were examined.

Results

Despite adequate GC morphology, a diminished memory and IgG⁺ B‐cell population along with diminished total and booster vaccine‐specific IgG‐producing memory B cells were noted in the spleens of macaques with past doxorubicin exposure compared to the saline‐treated controls (P < 0.05). Intact bulk T and T_FH cells were found in the SLTs of treated macaques, which displayed higher CD40L upregulation capacity by their splenic CXCR5⁺ helper T cells (P < 0.01). In contrast to the spleen, the immune cell populations studied were comparable between the lymph nodes of both saline‐ and doxorubicin‐treated macaques.

Conclusion

Our findings suggest that the splenic memory B‐cell subset, compared to its lymph node counterpart, is more severely altered by anthracycline treatment.

Altered proportions of circulating CXCR5+ helper T cells do not dampen influenza vaccine responses in children with rheumatic disease

Biological therapy options for the treatment of rheumatic disease target molecules that can affect the cross-talk between innate and adaptive immune responses upon vaccination. Influenza vaccination in children with rheumatic disease has been recommended, but there are only sparse data on the quality of vaccine responses from pediatric patients treated with biological therapy. We conducted an influenza vaccine study over 3 consecutive seasons where the antibody response to TIV was evaluated in children with PRD (n = 78), including both non-treated (n = 17) and treated (with methotrexate, TNF-inhibitors with or without methotrexate, or IL-inhibitors, n = 61) children as well as healthy age-matched controls (n = 24). Peripheral B cells, T and NK cell populations, as well as CXCR5+ (follicular) helper T cells (T_FH) and chemokines involved in antibody responses were assessed prior to immunization in the same cohort. Data on disease duration, therapy and data on previous influenza vaccinations were retrieved. The proportion of circulating T_FH cells were significantly lower in non-treated children with PRD compared to treated patients and healthy controls. The significantly lower proportion of T_FH cells was mirrored by a marked significant increase in CXCL13 serum level, the ligand for CXCR5, with higher levels in non-treated children with PRD compared to treated patients and healthy controls. However, the proportion of T_FH cells or CXCL13 level at the time of vaccination was not a predictor of the antibody response to TIV in this cohort of children. Children with PRD had an overall similar response to TIV as healthy children. Although not significant, children treated with TNF-inhibitors differed as a few children remained seronegative towards H3N2- and influenza B viruses after immunization. Our data show that children with PRD respond to TIV as healthy children. Furthermore, plasma CXCL13 levels did not correlate to the proportion of T_FH cells in blood prior to immunisation, or to antibody responses following immunization.