Recovery of blood T-cell subsets after chemotherapy for childhood acute lymphoblastic leukemia

Temporal evolution and differential patterns of cellular reconstitution after therapy for childhood cancers

The cellular reconstitution after childhood cancer therapy is associated with the risk of infection and efficacy of revaccination. Many studies have described the reconstitution after stem cell transplantation (SCT). The recovery after cancer treatment in children who have not undergone SCT has mainly been investigated in acute lymphoblastic leukemia (ALL), less for solid tumors. Here, we have examined the temporal evolution of total leukocyte, neutrophil and lymphocyte counts as surrogate parameters for the post-therapeutic immune recovery in a cohort of n = 52 patients with ALL in comparison to n = 58 patients with Hodgkin's disease (HD) and n = 22 patients with Ewing sarcoma (ES). Patients with ALL showed an efficient increase in blood counts reaching the age-adjusted lower limits of normal between 4 and 5 months after the end of maintenance therapy. The two groups of patients with HD and ES exhibited a comparably delayed recovery of total leukocytes due to a protracted post-therapeutic lymphopenia which was most pronounced in patients with HD after irradiation. Overall, we observed a clearly more efficient resurgence of total lymphocyte counts in patients aged below 12 years compared to patients aged 12 to 18 years. Our results underline that the kinetics of cellular reconstitution after therapy for HD and ES differ significantly from ALL and depend on treatment regimens and modalities as well as on patient age. This suggests a need for disease, treatment, and age specific recommendations concerning the duration of infection prophylaxis and the timing of revaccination.

Umbilical cord blood: A promising source for allogeneic CAR-T cells

Chimeric antigen receptor T (CAR-T) cell therapy is an effective treatment for relapsed and refractory acute lymphoblastic leukemia (R/R ALL). However, autologous CAR-T cells derived from patients with B-ALL often show poor amplification ability, exhaustion, and anergy. To overcome these limitations, allogeneic CAR-T cells may be used as effective substitutes; however, which source would be the best substitute is unclear. In this study, we compared the immunophenotype and antitumor efficacy of anti-CD19 CAR-T cells derived from healthy donor cord blood (CB), healthy donor peripheral blood (PB), and PB of B-ALL patients [PB (patient)] in vitro and NOD-Prkdcem26cd52Il2rgem26Cd22/Nju (NCG)-immunodeficient mice, respectively. The results revealed that CAR-T cells derived from healthy donor CB and PB showed a higher proportion of naive T cells and longer tumor suppression in tumor-bearing mice than those of PB (patient). PB (patient) CAR-T cells had a higher proportion of regulatory T cells (Treg cells) and released high levels of interluekin-10 (IL-10), which also suggest a poor prognosis. Thus, CAR-T cells derived from healthy donors have better antitumor efficacy than CAR-T cells derived from PB (patient), and CB may be a good source of allogeneic CAR-T cells.

Effect of GATA3 rs3824662 gene polymorphism in Han Chinese children with pre-B-cell acute lymphoblastic leukemia with 10 years follow-up

PURPOSE

To evaluate the influence of GATA3 rs3824662 on pre-B-cell acute lymphoblastic leukemia (pre-B-cell ALL) susceptibility and long-term prognosis in Han Chinese children with pre-B-cell ALL treated with the CCLG-2008 protocol at the Children's Hospital of Soochow University.

METHODS

A total of 256 patients with childhood pre-B-cell ALL under the CCLG-2008 protocol were enrolled in this study, and 174 healthy children were used as case controls. GATA3 rs3824662 genotyping was performed using a polymerase chain reaction, followed by Sanger sequencing. The association of genotype with clinical characteristics, treatment response, adverse events, and outcomes were analyzed.

RESULTS

The A allele frequency of GATA3 rs3824662 in patients with pre-B cell ALL was significantly higher than that in healthy children (OR = 1.41, 95% CI = 1.042-1.908; P = 0.026). Among patients with pre-B-cell ALL, the GATA3 rs3824662 AA genotype was associated with poor prednisolone response and high blast cell burden on day 15 of the induction therapy (P = 0.011 and 0.007, respectively). Patients with the rs3824662 AA variant suffered more episodes of sepsis than those with the CC or CA variants (P = 0.021). The GATA3 rs3824662 AA genotype was significantly associated with sepsis [hazard ratio (HR) = 3.375; P = 0.01]. No significant differences were found in the cumulative incidence of relapse, overall survival, and event-free survival among all genotypes.

CONCLUSION

GATA3 rs3824662 was associated with susceptibility in Han Chinese children with pre-B-cell ALL and could be a possible risk factor for poor early treatment response and treatment-related sepsis.

Baseline CD3+CD56+ (NKT-like) Cells and the Outcome of Influenza Vaccination in Children Undergoing Chemotherapy

Background

In children undergoing chemotherapy yearly influenza vaccination is recommended by treatment protocols. We investigated the relationship between cellular immunity and the antibody response to inactivated influenza vaccines.

Methods

25 patients (age: 2-18 years) undergoing chemotherapy for different malignancies participated in our study. Flow cytometric detection of peripheral blood lymphocyte subpopulations together with hemagglutination inhibition antibody titers were measured before and 21-28 days after vaccination. We examined the ratio and total numbers of CD3+, CD4+, CD8+ T cells, activated helper (CD3+CD4+CD25^low), regulatory (CD3+CD4+CD25^high), naive (CD3+CD45RA+) and memory (CD3+CD45RO+) T cells, CD56+NK, and CD3+CD56+ (NKT-like) cells. Relationships between specific antibody responses (seroprotection, seroconversion, geometric mean titer (GMT), geometric mean fold increase (GMFI)) and the ratios and counts of lymphocyte subpopulations were evaluated using one-way ANOVA and the paired sample t test after dichotomization according to age-related reference values.

Results

Patients with CD4+ lymphocyte levels in the normal age-specific range showed significantly better response regarding postvaccination GMT elevation for H1N1 and H3N2 strains (97.52 vs. 19.2, p=0.019, 80 vs. 14.43, p=0.021, respectively). GMFI results were significant only against B strain (2.69-fold vs. 1.23-fold, p=0.046). Prevaccination CD3+CD56+ (NKT-like) cells above predicted values according to age showed significant associations both in postvaccination GMT elevation (H1N1: 75.11 vs. 14.14, p=0.010; H3N2: 62.18 vs. 11.22, p=0.012; B: 22.69 vs. 6.67, p=0.043) and GMFI against all three strains (H1N1: 3.76-fold vs. 1.06-fold, p=0.015; H3N2: 2.74-fold vs. 1, p=0.013; B: 2.57-fold vs. 1, p=0.008). By one-way ANOVA, we found a positive relation between absolute lymphocyte cell count above 1000/µl and the postvaccination GMT elevation against H3N2 (12.81 vs. 56.56, p=0.032), and GMFI regarding H1N1 (1.22-fold vs. 3.48-fold, p=0.044).

Conclusions

In addition to verifying the predictive value of absolute lymphocyte count above 1000/µl, our results suggest an association between NKT-like cell counts and the specific antibody response against all three investigated influenza strains in highly immunosuppressed patients. Furthermore, prevaccination CD4+ lymphocyte levels in the normal age-specific range may influence seroresponse.

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.

Immune reconstitution in children following chemotherapy for acute leukemia

Although survival rates for pediatric acute lymphoblastic leukemia are now excellent, this is at the expense of prolonged chemotherapy regimens. We report the long-term immune effects in children treated according to the UK Medical Research Council UKALL 2003 protocol. Peripheral blood lymphocyte subsets and immunoglobulin levels were studied in 116 participants, at six time points, during and for 18-month following treatment, with 30-39 patients analyzed at each time point. Total lymphocytes were reduced during maintenance chemotherapy and remained low 18 months following treatment completion. CD4 T cells remained significantly reduced 18 months after treatment, but CD8 cells and natural killer cells recovered to normal values. The fall in naïve B-cell numbers during maintenance was most marked, but numbers recovered rapidly after cessation of treatment. Memory B cells, particularly nonclass-switched memory B cells, remained below normal levels 18 months following treatment. All immunoglobulin subclasses were reduced during treatment compared to normal values, with IgM levels most affected. This study demonstrates that immune reconstitution differs between lymphocyte compartments. Although total B-cell numbers recover rapidly, disruption of memory/naïve balance persists and T-cell compartment persist at 18 months. This highlights the impact of modern chemotherapy regimens on immunity, and thus, infectious susceptibility and response to immunization.

Changes in hepatitis B antibody status after chemotherapy in children with acute lymphoblastic leukemia

BACKGROUND

Children with cancer may be at an increased risk of infection with hepatitis B virus (HBV) when levels of hepatitis B antibodies are reduced owing to chemotherapy-induced immunosuppression. This study evaluated the changes in HBV antibody status and HBV infections after chemotherapy in children with acute lymphoblastic leukemia (ALL).

PROCEDURE

The data of patients with ALL diagnosed between April 2007 and March 2013 were retrospectively collected. Hepatitis B surface antibody (HBsAb) titers were defined as negative at levels <10 IU/L. The HBsAb titers were individually compared before and after chemotherapy.

RESULTS

A total of 88 patients were included in this study. At the time of diagnosis, 32 (36.4%) and 56 (63.6%) patients were HBsAb negative and HBsAb positive, respectively. The 56 HBsAb-positive patients were categorized into two groups, namely, group A with 44 patients (78.6%, 44/56) who became HBsAb negative after chemotherapy, and group B with 12 patients (21.4%) who remained HBsAb positive. On multivariate analysis, lower initial levels of HBsAb titers were associated with HBsAb negativity after chemotherapy (relative risk: 1.003, 95% confidence interval: 1.001-1.006; P = .009).

CONCLUSION

This study demonstrated that patients with a low level of prechemotherapy HBsAb titers were likely to become HBsAb negative after chemotherapy. Therefore, evaluation of HBsAb status may be necessary after the completion of chemotherapy in children with ALL.

Immune Thrombocytopenia in a Child With Refractory Langerhans Cell Histiocytosis Following Cladribine Containing Therapy

In this report, we present a young infant with multisystem Langerhans cell histiocytosis, who after cladribine and cytarabine salvage treatment developed immune thrombocytopenia (IT). On review of the literature, there were no previous reports of Langerhans cell histiocytosis-associated IT. Treatment of the IT with intravenous immunoglobulin and oral corticosteroids was unsuccessful. Eltrombopag, in combination with a 4-day course of dexamethasone was commenced as second-line therapy. Platelet recovery occurred 10 days after initiation of eltrombopag. The immune thrombocytopenia remains in long-term remission despite cessation of eltrombopag. Eltrombopag was safe and well tolerated.

Immunization status in childhood cancer survivors: A hidden risk which could be prevented

BACKGROUND

A limited number of studies have examined the vaccine-specific antibody status of children with cancer. There are disagreements over the guidelines for postcancer immunization strategy.

METHODS

Our study was an observational, cross-sectional retrospective review of data collected on children who were seen in the outpatient clinic at King Abdullah Medical City, Oncology Center, Jeddah, the Kingdom of Saudi Arabia. Our aim was to evaluate the seropositive status to vaccine-preventable diseases: measles, mumps, rubella, diphtheria, tetanus, polio, and Haemophilus influenzae type B (HIB) in childhood cancer survivors at our center in order to plan future vaccination for these children and establish a simple revaccination schedule.

RESULTS

Forty-seven patients (21 boys and 26 girls) were included in the study. Age at the time of cancer diagnosis (mean±standard deviation) was 5.68±3.79 years and age at test sampling was 10.68±3.79 years. Acute leukemia was the most common cancer (49% of patients), followed by lymphoma (28%), brain tumors (13%), and solid tumors (10%). Treatment intensities (according to the Treatment Intensity Rating Scale, version 3.0; ITR-3) were 2, 3, and 4 for 26 patients (55%), 20 patients (43%), and one patient (2.1%), respectively. We found that 93% of our patients were considered seronegative (unprotected) for at least one vaccine-preventable disease. The seronegative rates for measles, mumps, rubella, diphtheria, tetanus, polio, and HIB were 46.8%, 36.2%, 36.2%, 46.8%, 61.7%, 17.1%, and 42.6%, respectively. Criteria including age at diagnosis, age at sampling, type of malignancy, and treatment intensity were not significantly different between seropositive and seronegative patients.

CONCLUSION

Seronegative rates for vaccine-preventable diseases were very high in childhood cancer survivors, which represented a subpopulation of high-risk patients who could benefit from revaccination. We suggest a universal revaccination approach for all childhood cancer survivors, which is easily applicable and of low cost.

Varicella zoster immune status in children treated for acute leukemia

Children treated for acute leukemia are at increased risk of severe infection with varicella zoster virus (VZV). We studied the VZV sero-status of children with acute leukemia prior to starting chemotherapy and after completion of chemotherapy. VZV sero-status was assessed using time resolved fluorescence immunoassay (TRFIA) before starting treatment and 6 months after completion of treatment. Prior to starting treatment for acute leukemia, a significant proportion of children (35%) are VZV seronegative. On completion of treatment most patients maintained protective VZV antibody levels; however, 35% had reduced/loss VZV antibody to a level considered non-protective and susceptible to VZV infection.

Infections among long-term survivors of childhood and adolescent cancer: a report from the Childhood Cancer Survivor Study

BACKGROUND

Little is known about infections among adult survivors of childhood cancer. The authors report the occurrence of infections and risk factors for infections in a large cohort of survivors of childhood cancer.

METHODS

The Childhood Cancer Survivor Study cohort was used to compare incidence rates of infections among 12,360 5-year survivors of childhood cancer with the rates of 4023 siblings. Infection-related mortality of survivors was compared with that of the US population. Demographic and treatment variables were analyzed using Poisson regression to determine the rate ratios (RRs) and corresponding 95% confidence intervals (CIs) for associations with infectious complications.

RESULTS

Compared with the US population, survivors were at an increased risk of death from infectious causes (standardized mortality ratio [SMR], 4.2; 95% CI, 3.2-5.4), with the greatest risk observed among females (SMR, 3.2; 95% CI, 1.5-6.9) and among those who had been exposed to total body irradiation (SMR, 7.8; 95% CI, 1.8-33.0). Survivors also reported higher rates than siblings of overall infectious complications (RR, 1.3; 95% CI, 1.2-1.4) and higher rates of all categories of infection.

CONCLUSIONS

Survivors of childhood cancer remain at elevated risk for developing infectious-related complications, and they have a higher risk of infection-related mortality years after therapy. Further investigation is needed to provide insight into the mechanisms for the observed excess risks.

2013 IDSA clinical practice guideline for vaccination of the immunocompromised host

An international panel of experts prepared an evidenced-based guideline for vaccination of immunocompromised adults and children. These guidelines are intended for use by primary care and subspecialty providers who care for immunocompromised patients. Evidence was often limited. Areas that warrant future investigation are highlighted.

The effect of red ginseng extract on inflammatory cytokines after chemotherapy in children

Ginseng has been used as an herbal medicine, widely used in Asian countries, for long time. Recently, beneficial effects for immune functions of Korean red ginseng (KRG) have been reported in adults. This study was performed to investigate the effects of ginseng on immune functions in children after cessation of chemotherapy or stem cell transplantation for advanced cancer. Thirty patients, who were diagnosed and treated for leukemia and solid cancer at the department of pediatrics and adolescence of the Yeungnam University Hospital from June 2004 to June 2009, were enrolled for the study. The study group consisted of 19 patients who received KRG extract (60 mg/kg/d) for 1 yr and 11 patients who did not receive KRG extract were the control group. Blood samples were collected every 6 mo. Immune assays included circulating lymphocyte subpopulation, serum cytokines (IL- 2, IL-10, IL-12, TNF-alpha, and IFN-gamma), and total concentrations of serum IgG, IgA, and IgM subclasses. Age at diagnosis ranged from 2 mo to 15 yr (median 5 yr). Nine patients received stem cell transplantation. The cytokines of the KRG treated group were decreasing more rapidly than that of the control group. Lymphocyte subpopulations (T cell, B cell, NK cell, T4, T8, and T4/ T8 ratio) and serum immunoglobulin subclasses (IgG, IgA, and IgM) did not show significant differences between the study and the control groups. This study suggests that KRG extract might have a stabilizing effect on the inflammatory cytokines in children with cancer after chemotherapy.

Immune reconstitution in children following chemotherapy for haematological malignancies: a long-term follow-up

Modern intensive chemotherapy for childhood haematological malignancies has led to high cure rates, but has detrimental effects on the immune system. There is little knowledge concerning long-term recovery of the adaptive immune system. Here we studied the long-term reconstitution of the adaptive immune system in 31 children treated for haematological malignancies between July 2000 and October 2006. We performed detailed phenotypical and functional analyses of the various B and T cell subpopulations until 5 years after chemotherapy. We show that recovery of newly-developed transitional B cells and naive B and T cells occurred rapidly, within months, whereas recovery of the different memory B and T cell subpopulations was slower and incomplete, even after 5 years post-chemotherapy. The speed of B and T cell recovery was age-independent, despite a significant contribution of the thymus to T cell recovery. Plasmablast B cell levels remained above normal and immunoglobulin levels normalised within 1 week. Functional T cell responses were normal, even within the first year post-chemotherapy. This study shows that after intensive chemotherapy for haematological malignancies in children, numbers of several memory B and T cell subpopulations were decreased on the long term, while functional T cell responses were not compromised.

Pandemic influenza A (2009 H1N1) in children with acute lymphoblastic leukaemia

Pandemic influenza A (2009-H1N1) usually results in mild clinical illness, but in some individuals it can be life-threatening. There are no reports of this disease among paediatric patients with acute lymphoblastic leukaemia (ALL). We report ten consecutive patients with ALL and pandemic influenza treated in a single institution. Median age was 7 years (range: 3-12). All were treated with oseltamivir. There were no deaths. Two patients under intensive chemotherapy developed pneumonia and one required ventilatory support. ALL patients under maintenance treatment had mild disease. In conclusion, in our series only patients under intensive treatment developed a moderate to severe disease.

Immune-based therapeutics for pediatric cancer

IMPORTANCE OF THE FIELD

Although most children with cancer are cured, there remain significant limitations of standard treatment, most notably chemotherapy resistance and non-specific toxicities. Novel immune-based therapies that target pediatric malignancies offer attractive adjuncts and/or alternatives to commonly employed cytotoxic regimens of chemotherapy or radiotherapy. Elucidation of the principles of tumor biology and the development of novel laboratory technologies over the last decade have led to substantial progress in bringing immunotherapies to the bedside.

AREAS COVERED IN THIS REVIEW

Current immunotherapeutic clinical trials in pediatric oncology and the science behind their development are reviewed.

WHAT THE READER WILL GAIN

Most of the immune-based therapies studied to date have been well tolerated, and some have shown promise in the setting of refractory or high-risk malignancies, demonstrating that immunotherapy has the potential to overcome resistance to conventional chemotherapy.

TAKE HOME MESSAGE

Some immune-based therapies, such as ch14.18 and MTP-PE, have already been proven effective in phase III randomized trials. Further studies are needed to optimize and integrate other therapies into standard regimens, and to test them in randomized trials for patients with childhood cancer.

Impact of influenza-like illness and effectiveness of influenza vaccination in oncohematological children who have completed cancer therapy

In order to evaluate the impact of influenza-like illness and the effectiveness of influenza vaccination in children with oncohematological disease who have completed cancer therapy, 182 children with a diagnosis of oncohematological disease were divided into two subgroups on the basis of the length of time off therapy (<6 months or 6-24 months) and randomised 1:1 to receive influenza vaccination or not. The controls were 91 otherwise healthy children unvaccinated against influenza. The results show that the clinical and socioeconomic impact of influenza-like illnesses and the effectiveness of influenza vaccination in oncohematological children who have completed cancer therapy are related to the length of the off therapy period, and seem to be significantly greater in those who have been off therapy for less than 6 months in comparison with healthy controls. This suggests that the administration of influenza vaccination should be strongly recommended only among oncohematological children who have been off therapy for less than 6 months.

Humoral immune response after post-chemotherapy booster diphtheria-tetanus-pertussis vaccine in pediatric oncology patients

BACKGROUND

The role of post-chemotherapy booster vaccination in pediatric oncology children remains to be established. In this randomized controlled study, we studied the effect of immune responses to diphtheria-tetanus-pertussis (DTP) booster vaccination in children 6 months after completing chemotherapy.

METHODS

Children 1-18 years old with chemotherapy completed for 6 months (baseline) were eligible. Subjects were randomized into vaccine and control group. In the former, three doses of DTP vaccine (Aventis Pasteur Inc., Lyon, France) were administered. IgG antibody titers against diphtheria, tetanus, pertussis, hepatitis B, measles, mumps, and rubella antibodies were measured serially in vaccine and control groups. Subsets of circulating lymphocytes (CD3(+), CD4(+), CD8(+), CD19(+), and CD16/56(+)) were quantified by flow cytometry using fluorescence-labeled monoclonal antibodies.

RESULTS

Fifty-six children (28 vaccinees; 28 controls) were enrolled. Protective antibody levels against diphtheria, tetanus, pertussis were found at baseline in 83.6%, 96.5%, 96.1% of them respectively. After three doses of DTP, all vaccinees demonstrated a sustain rise in antibody levels and the antibody titers were significantly higher than control group. 35.8% of subjects were susceptible to measles mumps and rubella infection and 69% showed anti-HBs antibody titer less than protective level up to 18 months after stopping chemotherapy.

CONCLUSIONS

Post-chemotherapy booster vaccinations produced a strong and sustained effect in humoral immunity against vaccine-preventable infectious diseases.

Longitudinal assessment of immunological status and rate of immune recovery following treatment in children with ALL

BACKGROUND

We prospectively evaluated the immunological status, immune recovery and risk of infection in pediatric ALL patients treated on the BFM 95 protocol.

PROCEDURE

Humoral and cellular immunity were evaluated in 72 children with ALL at the end of intensive therapy and values were compared to those at the completion of therapy and 6-monthly. Parameters investigated included lymphocyte subpopulation by flow cytometry, immunoglobulin levels by nephelometry, antibody titers to previous immunizations and delayed hypersensitivity with skin testing. Immune responses were correlated to duration of therapy, CNS radiotherapy, age and sex.

RESULTS

Humoral immunity was severely depressed by the end of intensive therapy with low immunoglobulin levels and CD19, improved after therapy cessation. Cellular immune responses were normal at the end of intensive treatment but declined significantly by the end of therapy and both CD4 and CD8 remained low at later evaluation points whereas CD4/CD8 ratio was increasing. Duration of therapy and CNS radiotherapy did not affect the rate of immune recovery whereas female had higher CD19, CD45RO, and IgM and children >7 years had higher CD19 and lower CD16 and CD3DR. Among immunized children, 86.7% maintained protective antibodies to MMR and 63% to polio. Despite impairment of immunity, infections outside the neutropenic periods were common viral illnesses.

CONCLUSION

Humoral immunity was depressed in children with ALL at the end of intensive therapy but began to recover after cessation of therapy. In contrast, cellular immunity declined significantly by the end of therapy and remained abnormal for at least 1 year post-therapy.

Vaccinations in children treated with standard-dose cancer therapy or hematopoietic stem cell transplantation

Most children with cancer are immunocompromised during therapy and for a variable period after completion of therapy. They are at an increased risk of infections, including vaccine-preventable infections. There is a reduction in immunity to vaccine-preventable diseases after completion of standard-dose chemotherapy and after hematopoietic stem cell transplant. It is important to protect these children against vaccine-preventable diseases by reimmunization.

Immune response to conjugated meningococcal C vaccine in pediatric oncology patients

BACKGROUND

Following outbreaks of meningococcal disease in Quebec in 1991-1993 and 2000-2001, a mass vaccination campaign was performed. In 2001-2002, children aged 2 months to 20 years were immunized with the Meningococcal CRM197 vaccine (Menjugate). We examined the response of pediatric oncology patients during or following maintenance chemotherapy and post-bone-marrow transplantation to Meningococcal C vaccine.

PROCEDURE

This was an open label descriptive study of a cohort of patients from the oncology clinic at the Montreal Children's Hospital. A positive vaccine response was defined as a fourfold increase in specific IgG from baseline and a bactericidal assay using human complement (hBCA) titer >1:4.

RESULTS

Of the 25 patients with ALL, 13 had a serologic response (average 60-fold increase). The serologic responders had a higher mean B cell count (0.262) compared to non-responders 0.068 x 10.9/L [t(23) = 2.843 (P < 0.05)]. Eleven of the 12 non-responders and 4 of the responders were on maintenance chemotherapy. In addition, two of the five patients post-bone-marrow transplant, responded. Fifteen of the 34 patients (44%) had an adequate hBCA response (mean titer 61). The group included 14/18 serologic responders with hBCA response (P < 0.001) and 16/17 non-serologic responders with no hBCA response (P < 0.001).

CONCLUSIONS

Meningococcal C-conjugate vaccine produced variable responses in children with common cancers. Proximity to chemotherapy and total B cell number may help predict likelihood of response.

Revaccination of Children after Completion of Standard Chemotherapy for Acute Leukemia

BACKGROUND

After the treatment of patients with acute leukemia, there is a decrease in vaccine-specific antibody and an increased susceptibility to certain vaccine-preventable diseases. A simple revaccination schedule is warranted.

METHOD

Fifty-nine children (age, 1-18 years) who had completed standard chemotherapy in accordance with Medical Research Council of United Kingdom protocols were recruited. All children received a single dose of Haemophilus influenzae type b (Hib), tetanus, diphtheria, acellular pertussis, meningococcus C, polio, measles, mumps, and rubella vaccines > or = 6 months after completion of treatment. Antibody concentrations were measured before vaccination and 2-4 weeks and 12 months after vaccination.

RESULTS

Prevaccination antibody levels were protective for all patients for tetanus (geometric mean concentration [GMC], 0.13 IU/mL; 95% CI, 0.1-0.17 IU/mL), for 87% for Hib (GMC, 0.5 microg/mL; 95% CI, 0.37-0.74 microg/mL), for 71% for measles (GMC, 301 mIU/mL; 95% CI, 163-557 mIU/mL), for 12% for meningococcus C (geometric mean titer [GMT], 1:2.9; 95% CI, 1:2.2 to 1:3.9), and for 11% for all 3 poliovirus serotypes. Revaccination resulted in a significant increase in levels of antibody to each vaccine antigen, with 100% of patients achieving optimal antitetanus antibody concentrations (defined as > 0.1 IU/mL; 1.5 IU/mL; 95% CI, 1.1-2.1 IU/mL), 93% achieving optimal antibody concentrations to Hib (defined as > 1.0 microg/mL; 6.5 microg/mL; 95% CI, 5.1-8.2 microg/mL), 94% achieving optimal antibody concentrations to measles (defined as > or = 120 mIU/mL; 2720 mIU/mL; 95% CI, 1423-5198 mIU/mL), 96% achieving optimal antibody concentrations to meningococcus C (defined as > or = 1:8; 1:1000; 95% CI, 1:483-1:2064), and 85% achieving optimal antibody concentrations to all the 3 poliovirus serotypes (defined as > or = 1:8). For the majority of subjects, protection persisted for at least 12 months after vaccination.

CONCLUSION

Revaccination of children after standard chemotherapy is important, and protection can be achieved in the majority of these children using a simple schedule of 1 vaccine dose at 6 months after completion of leukemia therapy.

Immune thrombocytopenia following successful treatment of cancer in children

A predisposition to developing immune thrombocytopenia (ITP) has not been reported in survivors of childhood cancer. We report a case series of childhood cancer survivors who developed an isolated thrombocytopenia in the presence of a normocellular bone marrow. Five children, two with endodermal sinus tumors and three with acute lymphoblastic leukemia, developed ITP at a median of 4 years (range: 0.2-8 years) after completion of therapy. We suggest the association of ITP in survivors of childhood malignancy may not be co-incidental as chemotherapy may cause persistent immune dysfunction.

Decreased numbers of CD4+ T lymphocytes in peripheral blood after treatment of childhood acute lymphoblastic leukemia

Treatment-related immunosuppression in patients with acute lymphoblastic leukemia (ALL) is associated with increased susceptibility to infectious diseases, also after the treatment. The aim of the present study was the detailed evaluation of T lymphocyte subsets in peripheral blood in children after treatment of ALL. All children were treated according to the BFM 90 protocol. The patients were divided into 5 groups of 30 children in each, depending on the time from cessation of the ALL treatment. A control group consisted of 30 healthy children subjected to elective "1-day" surgery. The children's age ranged from 6 to 18 years. The examinations were performed in FACScan flow cytometer with the use of wide set of monoclonal antibodies: CD3, CD4, CD8, TCRalphabeta, TCRgammadelta, CD19, CD25, CD45RA, CD45RO, CD69, HLA-DR, CD16 and CD56, which particularly allowed detailed analysis of T lymphocytes. The results showed that most parameters in children 1 year after ALL treatment completion were similar to healthy children. However, we observed persistently low CD4+ T cell numbers, both CD45RA+ as well as CD45RO+ subsets as compared to the control group. This might reflect decreased regenerative potential of immunological system in children 1 year after ALL treatment.

Immune reconstitution after childhood acute lymphoblastic leukemia is most severely affected in the high risk group

OBJECTIVE

The aim was to examine the immune reconstitution after current chemotherapy for childhood ALL, with a special focus on finding immunologic variables that predict a poor immune response to vaccinations.

PROCEDURE

In a cross-sectional study of 31 children after treatment with the NOPHO ALL-1992 protocol peripheral blood lymphocyte subsets, T- and B-cell function in vitro and serum immunoglobulins (Ig) were measured. All patients were examined once, at 1 or at 6 months after cessation of chemotherapy, immediately before vaccination with DT and Hib.

RESULTS

Lymphocytes, T-cells, and CD4+ T-cells were low at 6 months after treatment. Naive T-cell subsets were more reduced than memory subsets. In the high risk (HR) ALL group, CD8+ T-cells were reduced at 6 months. NK-cells were low at 1 month, but normal at 6 months; however, the CD3+CD56+ (NKT) subset was reduced at both time points. Total B-cell number was low at 1 month, but normal at 6 months. A relative increase of CD5+ B-cells (B-1 cells) was evident, particularly in the HR group. Antigen-independent T- and B-cell function in vitro were affected at 1 month, but virtually normalized at 6 months. Serum IgM level was decreased at 1 month and IgG3 level was increased at 1 and 6 months.

CONCLUSIONS

This study shows that immune reconstitution after childhood ALL is slower than previously reported and emphasizes the influence of treatment intensity. The most intensively treated patients still have persistent abnormalities in T-, B-, and NK-cell subsets at 6 months post therapy and show a poor response to immunization with T-cell dependent antigens. In the HR group, routine re-immunizations before this time point are of limited benefit, and the effect of repeated vaccinations should be evaluated.

Intensive treatment for childhood acute lymphoblastic leukemia reduces immune responses to diphtheria, tetanus, and Haemophilus influenzae type b

OBJECTIVES

Immunity to diphtheria toxoid (D), tetanus toxoid (T), and Haemophilus influenzae type b (Hib) is affected in children with acute lymphoblastic leukemia (ALL). The aims were to examine immunity and to compare the response to immunization at 1 or 6 months after treatment.

METHODS

Thirty-one patients were immunized with DT and conjugated Hib vaccine (ActHib) at 1 month or 6 months after treatment of ALL with the NOPHO 92 protocol. Antibody levels were determined before and 3 weeks after vaccination. Specific T and Hib antibody-secreting cells of IgG/IgA/IgM isotypes were analyzed in peripheral blood using an ELISPOT technique.

RESULTS

All specific antibody levels decreased during ALL treatment, and protective levels after treatment were noted for 17% against D, 33% against T, and 100% against Hib. No high-risk patient had full D or T protection after treatment. After vaccination all the standard- and intermediate-risk patients achieved full protection against D, T, and Hib. The high-risk group showed insufficient immune response (full protection after vaccination: D 56%, T 22%, Hib 78%). No difference was found between vaccination at 1 month or 6 months after treatment. The poor antibody production in the high-risk group correlated to low numbers of antibody-secreting cells.

CONCLUSIONS

Nonprotective antibody levels against D, T, and Hib after childhood ALL are more common than previously thought. Insufficient immune response was restricted to the high-risk group and was related to a low number of memory B cells in this study. Immunizations should be included in follow-up after childhood ALL, and the policy should be adapted to treatment intensity.

Current chemotherapy protocols for childhood acute lymphoblastic leukemia induce loss of humoral immunity to viral vaccination antigens

OBJECTIVE

To evaluate viral vaccination immunity and booster responses in children treated successfully for acute lymphoblastic leukemia by chemotherapy and to study the response to treatment of antibody-producing plasma cells that are important for persistence of humoral immunity.

METHODS

Forty-three children who were in continuous first remission for a median of 5 years (range: 2-12 years) were studied. Before the leukemia was diagnosed, all children had been immunized against measles, mumps, and rubella according to the Swedish National immunization program. We analyzed levels of serum antibodies against measles and rubella by enzyme immunoassays. Avidity tests for measles antibodies were concomitantly performed by enzyme-linked immunosorbent assay for measles virus immunoglobulin G detection. The proportion of plasma cells in bone marrow was studied by flow cytometry at different times during treatment and follow-up. Children who lacked protective levels of antibodies to vaccination antigens were reimmunized. Serum was collected 3 months after immunization to assess vaccination responses.

RESULTS

After completion of the treatment, only 26 of the 43 children (60%) were found to be immune against measles and 31 (72%) against rubella. The proportion of bone marrow plasma cells decreased during treatment but returned to normal after 6 months. Revaccination caused both primary and secondary immune responses. Six of the 14 children without immunity failed to achieve protective levels of specific antibodies against measles and 3 against rubella.

CONCLUSIONS

Our finding of loss of antibodies against measles and rubella in children treated with intensive chemotherapy suggests that reimmunization of these patients is necessary after completion of the treatment. To determine reimmunization schedules for children treated with chemotherapy, vaccination responses need to be studied further.

Langerhans cell histiocytosis following childhood acute lymphoblastic leukemia

Langerhans cell histiocytosis (LCH) is a clonal proliferation of Langerhans cells of unknown etiology that results in a range of clinical manifestations. LCH has been known to be associated with a variety of malignant diseases. A 7-year-old boy was treated for standard-risk acute lymphoblastic leukemia (ALL) at age 2 years, on a Children's Cancer Group chemotherapy protocol for 3 years and developed LCH 2 years after completion of chemotherapy. The case and a review of literature on the association of LCH and ALL are presented.

Intact T-cell regenerative capacity in childhood acute lymphoblastic leukemia after remission induction therapy

BACKGROUND

Acute lymphoblastic leukemia (ALL) is a bone marrow disease. This may adversely affect the capacity of T cells to recover from chemotherapy-induced T-cell depletion and thus contribute to the prevailing immune deficiency in ALL patients.

PROCEDURE

We tested the capacity of T-cells to regenerate in 18 ALL children in first clinical remission (median age 4.2 years) at the time of hematologic reconstitution after BFM-ALL induction therapy (treatment-free interval 22 days, median; range 12 to 52 days). All patients had experienced a period of leukopenia (white blood cell count [WBC] <0.95 x 10(9)/l, median) during the final four weeks of induction therapy. T-cells and T-cell subsets were examined by FACS.

RESULTS

At the time of investigation the WBC was near normal (3.5 x 10(9)/l, median). Surprisingly, most cases (78%) showed a complete regeneration of T-cells and its subsets including 1) normal total (CD3+) T-cells (1635/microl, median; range 756-3440/microl); 2) normal T-helper (CD4+) cells (697/microl, median; range 128-1523/microl); and 3) normal T-cytotoxic/suppressor (CD8+) cells (686/microl, median; range 348-1540/microl). Eight patients achieved a normal CD4+/CD8+ ratio (0.8, median). Subset analyses of T-helper cells revealed a normal proportion of CD4+CD45RA+ cells (52%, median) in all but one patient below the age of 6 years, indicating an intact residual thymic activity. No correlation was observed between age at diagnosis and a normal CD4+ count (r = 0.086) or between a normal CD4+ count and a normal proportion of CD4+CD45RA+ cells r = 0.136). A long-term survey in four patients showed altered T-cells after reinduction and during maintenance therapy.

CONCLUSIONS

The findings suggest that ALL per se does not inhibit T-cell regenerative capacity. Thus, the frequently observed longlasting impairment of the T-cell system in ALL is attributable to the treatment rather than to the underlying disease.

Humoral immunity against diphtheria, tetanus and poliomyelitis after antineoplastic therapy in children and adolescents--a retrospective analysis

Serum antibodies against diphtheria- and tetanus-toxin were measured in 71 children and against poliomyelitis viruses 1-3 in 65 children and adolescents 0-18 months after cessation of antineoplastic therapy. Non or marginally protective serum titers were found in 62% of patients against diphtheria, in 18% of patients against tetanus and in 72% of patients against one or more poliomyelitis virus serotypes. Of these patients, 55%, 46% and 75% were immunized adequately according to age against diphtheria, tetanus and poliomyelitis, respectively. In 50% or more of patients a lack of protective immunity against diphtheria, tetanus and poliomyelitis was found which could not be explained by an inadequate immunization status. This suggests that other factors (e.g. influence of underlying illness, antineoplastic therapy or both on lymphocytes) might be responsible for these findings and this deserves further investigation. Measurement of serum antibodies against vaccine-preventable illnesses and consecutive booster immunizations are an essential part of long-term follow up in pediatric patients after antineoplastic therapy.

Military service of male survivors of childhood malignancies

BACKGROUND

The objective of this study was to assess the eligibility for and the course of compulsory military service of childhood cancer survivors.

METHODS

The medical, military recruitment, conscription, and military service data of male Finnish childhood cancer survivors were collected from manually filed records. Inclusion criteria were: survivors born 1977 or earlier, treated for a malignancy between birth and age 15 years, and followed by a pediatrician until at least age 18 years. The documents of 207 survivors from the Pediatric Clinics of Finnish University Hospitals were examined, and 130 of these survivors were considered eligible for military service. Demographic factors, the predictors of fitness for military service, factors associated with service interruption, the attained level of military training, and the health status of conscripts during service were evaluated. Comparisons were made with the Finnish male population of the same age and with conscripts serving at the corresponding time.

RESULTS

Approximately 60% of studied survivors were enlisted. Positive predictors of fitness for service were year of birth of 1973 or later (odds ratio [OR], 3.2), height at call-up age of 170-174.9 cm (OR, 3.6), and the man's own positive opinion of his fitness for service (OR, 62.3). Negative predictors were age at diagnosis > or = 11 years (OR, 0.5), central nervous system radiotherapy (OR, 0.3), limb defects (OR, 0.02), and the group of sequelae concerning neurologic, cardiopulmonary, and gastrointestinal systems, or secondary malignancies (OR, 0.3). Survivors interrupted their service more often (20%) (P < 0.001). Leukemia survivors were less likely to interrupt their service (7%) compared with other survivors (P = 0.04). Factors associated with service interruption were: diagnosis (P = 0.04), the man's own opinion of his fitness for service (P = 0.013), surgery (P = 0.003), and height (P = 0.049), weight (P = 0.019), and body mass index (P = 0.035) at the beginning of military service. The attained level of military training was equal to that of controls. The survivors visited the garrison physician less frequently in total (mean, 5.9 times) (P < 0.001), visited because of infections as much as controls, and were off duty more (mean, 11.9 days) (P = 0.012) than controls.

CONCLUSIONS

The current study found that childhood cancer survivors were less likely to meet the requirements set for military service in Finland. The causes of rejection usually were obvious, but approximately 30% were rejected merely on the basis of a former cancer diagnosis. However, enlisted survivors coped well with military service if their treatment sequelae were taken into consideration carefully at the time of enlistment. Vocational opportunities within the armed forces might be an appropriate career option even for survivors of childhood malignancies.