Immunodeficiency in children with acute lymphoblastic leukemia after completion of modern aggressive chemotherapeutic regimens

Postchemotherapy immune status in infants with acute lymphoblastic leukemia: A report from the JPLSG MLL-10 trial

The MLL-10 trial (UMIN000004801) modified a Children's Oncology Group (COG) AALL0631 therapy for infants with KMT2A-rearranged acute lymphoblastic leukemia (ALL). In 2016, one registered case developed secondary immunodeficiency during maintenance therapy and eventually died due to cytomegalovirus infection. Around the same time, fatal secondary immunodeficiencies were reported in five infants with ALL in North America who had received COG-based chemotherapy between 1996 and 2015. Given these cases, we decided to conduct a retrospective study on the postchemotherapy immune status of infants with ALL. A questionnaire collected data on posttreatment immune function, frequency of infections, and supportive care for the 34 infants in the MLL-10 trial. Patients receiving allogeneic hematopoietic stem cell transplantation in first remission were excluded. Responses to the survey were obtained in 28 cases (85%). Most patients were immunocompetent after the completion of chemotherapy (median follow-up duration from the day of chemotherapy completion was 431 days), except for the aforementioned case. There were seven patients with nonsevere viral infection, all of whom recovered. In conclusion, severe chemotherapy-induced immunodeficiency in infants with ALL appears to be rare, but prospective data collection of immune function is necessary to clarify this finding.

Molecular characterization of hepatitis B virus (HBV) isolated from a pediatric case of acute lymphoid leukemia, with a delayed response to antiviral treatment: a case report

BACKGROUND

Tenofovir disoproxil fumarate (TDF) is effectively used as the first-line antiviral for chronic hepatitis B virus (HBV) infection in adults and children older than 12 years. To date, no confirmed case of virologic breakthrough (VBT) in a pediatric case has been reported.

CASE PRESENTATION

Here we describe a case of a 5-year old, asymptomatically infected with HBV infection two months after chemotherapy for precursor B acute lymphoblastic leukemia (ALL). Although the 5-year old male is South African, his family originated from Guinea. At the end of the one-year follow-up, the infection progressed to chronic HBV infection, with a high viral load. At 36 weeks (8 months) post-treatment with lamivudine (LAM), there was a partial virologic response (PVR) and after 61 weeks (14 months), he was switched to TDF rescue monotherapy. Even with TDF treatment, he still experienced VBT and subsequent PVR. The full-length genome of HBV isolated 78 weeks after the switch to rescue TDF monotherapy was sequenced and belonged to genotype E. In addition to the LAM mutations (rtS256G and rtM267L), missense mutations in B-cell, T-cell, HLA class I and II-restricted epitopes emerged, which were to evade and escape host surveillance, leading to delayed viral clearance, persistence and disease progression. Two further events of VBT occurred between weeks 113 and 141 of TDF rescue-therapy. Viral loads and liver enzymes are normalizing progressively with long-term therapy.

CONCLUSION

Although the host immune reconstitution may be delayed, prolonged TDF treatment was effective in treating this pediatric case of HBV infection with VBT and PVR.

Chemotherapy-Induced Serological Impact in Hepatitis B Surface Antibody Titers in Children with Acute Lymphoblastic Leukemia

Objective In our study, we aimed to assess the differences in antibody titers against hepatitis B virus (HBV) prior and post leukemia therapy in children with acute lymphoblastic leukemia (ALL).

Methods Serum hepatitis B surface antibody (anti-HBs) levels of 96 ALL patients were compared before and postcessation of leukemia therapy from patients' medical records.

Results Fifty-five patients were male (57.2%) and 41 patients were female (42.7%), and the mean age was 6.1 years (range, 1 ± 15 years) at the time of diagnosis. Thirty (32.3%) patients were anti-HBs negative, and 66 (68.7%) patients were anti-HBs positive at initial diagnosis. Anti-HBs–positive 66 patients were categorized into two groups, the first group consisted of 28 (42.4%) anti-HBs–negative patients, and the second group consisted of 38 (57.6%) anti-HBs–positive patients after leukemia therapy. On binary logistic regression analysis, lower initial anti-HBs titers were found to be related to anti-HBs negative results post leukemia therapy (relative risk = 3.696, 95% confidence interval: 2.046–6.678; p = 0.001). The area under the curve was 0.849 with 76.1% sensitivity (95% confidence interval: 0.60–0.87; p = 0.001) and 82.6% specificity (95% confidence interval: 0.69–0.91; p = 0.001); the initial anti-HBs titer cut-off value was found 42.9 IU/L.

Conclusion Patients with low-serum anti-HBs titers before leukemia therapy were likely to become anti-HBs negative post leukemia therapy. Therefore, it is necessary to evaluate anti-HBs titers after completing immunosuppressive therapy in patients with ALL.

Thirteen-Valent Pneumococcal Conjugate Vaccine in Children With Acute Lymphoblastic Leukemia: Protective Immunity Can Be Achieved on Completion of Treatment

BACKGROUND

Children with acute lymphoblastic leukemia (ALL) are at increased risk of developing invasive pneumococcal disease. This study describes the immunogenicity of 13-valent pneumococcal conjugate vaccine (PCV13) during and after chemotherapy.

METHODS

Children with ALL were allocated to study groups and received a single dose of PCV13: group 1, maintenance chemotherapy; group 2, end of chemotherapy; group 3, 6 months after chemotherapy. A protective vaccine response was defined as at least 10 of 12 serotypes (or >83% of serotypes with data) achieving postvaccination serotype-specific immunoglobulin G ≥0.35 µg/mL and ≥4-fold rise, compared to prevaccination at 1 and 12 months.

RESULTS

One hundred eighteen children were recruited. Only 12.8% (5/39; 95% confidence interval [CI], 4.3%-27.4%) of patients vaccinated during maintenance (group 1) achieved a protective response at 1 month postvaccination and none had a protective response at 12 months. For group 2 patients, 59.5% (22/37; 95% CI, 42.1%-75.3%) achieved a response at 1 month and 37.9% (11/29; 95% CI, 20.7%-57.7%) maintained immunity at 12 months. For group 3 patients, 56.8% (21/37; 95% CI, 39.5%-72.9%) achieved a protective response at 1 month and 43.3% (13/30; 95% CI, 25.5%-62.6%) maintained immunity at 12 months.

CONCLUSIONS

This study demonstrated that the earliest time point at which protective immunity can be achieved in children with ALL is on completion of chemotherapy. This is earlier than current recommendations and may improve protection during a period when children are most susceptible to infection.

CLINICAL TRIALS REGISTRATION

EudraCT 2009-011587-11.

Post-Chemotherapy Titer Status and Need for Revaccination After Treatment for Childhood Cancer

Objectives. To evaluate the strategy of checking vaccine titers after completion of chemotherapy. Study Design. Retrospective review of pediatric oncology patients who completed chemotherapy. Demographics, post-chemotherapy titers, and absolute lymphocyte counts (ALCs) were analyzed. Results. Ninety patients met inclusion criteria, and 87% of patients had at least one titer checked. Comparing patients <7 years and those ≥7 years at diagnosis, there was no difference in incidence of negative titers except mumps; those <7 years old were more likely to have negative titers (58% vs 20%, P = .003). Comparing those <13 years old to ≥13 years old, there was no difference in negative titers except mumps (45% vs 19%, P = .02) and tetanus (44% vs 0%, P = .002). No patient maintained all protective titers after completion of chemotherapy. Time to ALC recovery was not predictive of positive titers. Conclusion. Checking titers after chemotherapy is not recommended. Providers should assume loss of immunity.

Haemophilus influenzae type b capsular polysaccharide antibody levels in Japanese young patients with hematological malignancies and asplenia

Individuals with immunosuppressive condition have a high risk of invasive Haemophilus influenzae type b (Hib) infection. In Japan, routine Hib vaccination program for children under 5 years old was introduced in December 2008. However, the national policy does not make provision for individuals aged ≥5 years who have medical conditions associated with a high risk of invasive Hib disease to receive Hib vaccine. We measured serum anti-polyribosylribitol phosphate specific (anti-PRP) antibodies to Hib in patients aged ≥5 years with hematological malignancies and asplenia and evaluated their levels of anti-PRP antibodies in post administration of Hib vaccine era. A total of 65 patients (48 with hematological malignancies, and 17 with asplenia) were included in this study, of which 84% had not received Hib vaccine. In addition, 95.4% had short-term protective levels of anti-PRP antibodies (defined as ≥0.15 μg/mL) and 41.5% had long-term protective levels of anti-PRP antibodies (defined as ≥1.0 μg/mL). Five patients had low anti-PRP antibody levels despite a history of Hib vaccination. Our results suggest that young patients with underlying diseases such as hematological malignancies and asplenia may be at risk of invasive Hib disease. Hence, we recommend they should receive Hib vaccines even if they are over the age limit for routine Hib vaccination program.

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.

Invasive Haemophilus Influenzae Type B Infections in Children with Cancer in the Era of Infant HIB Immunization Programs (1991-2014): A Report From the Canadian Immunization Monitoring Program Active

We studied the epidemiology of Haemophilus influenzae type b infections among children with cancer admitted to Canadian pediatric hospitals. From 1991 to 2014, 13 cases among children with cancer were identified through active surveillance. Average age was 6.7 years. Six of 7 cases eligible for infant immunization were age-appropriately immunized (vaccine failures). Children with cancer may benefit from booster Hib immunization.

Humoral immune response of childhood acute lymphoblastic leukemia survivors against the measles, mumps, and rubella vaccination

BACKGROUND

There is a great risk of infection with viral-vaccine-preventable diseases like measles, mumps, and rubella (MMR) infections after the end of chemotherapy treatment of children with acute lymphoblastic leukemia (ALL), which could have been prevented with MMR vaccination. Previous studies reported widely variable rates of seropositivity (seroprotection) for MMR after ALL treatment ends. Also, few studies evaluated the response to MMR booster vaccinations after the end of ALL treatment and reported unclear and difficult to interpret results.

MATERIAL AND METHODS

This retrospective cross-sectional study evaluated the prevalence of seropositive (protection) antibody titer levels for MMR among ALL childhood survivors who were followed-up at Jeddah Oncology Center, Saudi Arabia. The aim of the study was also to investigate and analyze the response of seronegative patients to a booster MMR vaccination.

RESULTS

Fifty-seven ALL children were evaluated. Thirty-five patients (61.4%) were seropositive/seroprotected and the remaining 22 patients (38.6%) were seronegative for MMR. ALL Children under the age of 5 years had a higher prevalence of seronegative titers. Interestingly, the prevalence of seroprotection decreased as the time interval increased post-treatment, while seroconversion rates after administering a booster MMR vaccine were 57.1%, 87.5%, and 78.6%, respectively for MMR.

CONCLUSION

We suggest the need for booster MMR vaccination, especially for ALL children under the age of 5 years and those who experienced a protracted time interval post-treatment.

Assessment of Humoral Immunity to Hepatitis B, Measles, Rubella, and Mumps in Children After Chemotherapy

BACKGROUND

Cancer survival rates and longevity of patients after therapy have significantly improved during the last few decades. Therefore, lasting protection against infections should be provided.

PROCEDURE

A total of 162 children diagnosed with acute lymphoblastic leukemia, acute myelogenous leukemia, solid tumors, non-Hodgkin lymphoma, and Hodgkin lymphoma were enrolled in the study. Antibody levels against hepatitis B virus was assessed both at the time of diagnosis and within 6 months after completion of chemotherapy. However, measles, mumps, and rubella (MMR) antibodies levels were measured just within 6 months after completion of chemotherapy.

RESULTS

Anti-HBs antibody titers had decreased below the protective level after treatment in 25 of 96 patients having protective antibody levels for hepatitis B virus before therapy. In 66 patients without pretreatment protective levels of antibody, in spite of the immunization during chemotherapy, only 6 of them were found to be anti-HBS positive after treatment. In 153 patients previously vaccinated with MMR, 19 had protective antibody titers after treatment. MMR seropositivities were negatively correlated to age as expected.

CONCLUSIONS

Our data demonstrate that a significant number of children lose preexisting humoral immunity against MMR and hepatitis B after completion of chemotherapy.

Dynamic re-immunization of off-treatment childhood cancer survivors: An implementation feasibility study

There are no universally approved re-vaccination guidelines for non-transplant pediatric cancer survivors. We hypothesized that by utilizing a response-based re-vaccination schedule, we could tailor vaccine schedules in off-treatment cancer survivors. Pre-vaccination antibody levels were obtained in 7 patients at an average of 20 days after the end of treatment date. In those without protective antibody levels, we administered vaccines 3 months after completion of treatment. Revaccinating patients 3 months after the end of treatment date resulted in protective antibody levels for most vaccines. We showed, on a preliminary basis, that vaccinating non-transplanted pediatric cancer survivors can be dynamically implemented in children with recovering immune function.

Assessment of hepatitis B virus antibody titers in childhood cancer survivors

Pediatric patients suffering from cancer are at risk of hepatitis B virus (HBV) infection and its related complications even though it is considered a vaccine preventable disease. Little is known of the effects of chemotherapy, and even less is known regarding the impact of HBV booster on HBV antibody titers. It is the purpose of this study to investigate and measure the prevalence of the antihepatitis B surface antibodies (HBsAb) in childhood cancer survivors after completion of their chemotherapy treatment and to further evaluate survivors' response to a single booster dose of HBV vaccine. This observational, cross-sectional retrospective study included 43 patients, of which 37 (86%) were found to be seronegative (HBsAb titer <10 mIU/ml). The notable result was that, of the seronegative patients who received a booster dose of HBV vaccine, 90% of the tested cases exhibited a successful raising of HBsAb titers >10 mIU/ml.

CONCLUSION

Childhood cancer survivors have high seronegative rates for HBV and the majority of the patients achieved HBsAb titer > 10mIU/ml with a single booster dose of HBV vaccine, which is worth further investigation and research. This study suggests revaccination against HBV post-chemotherapy treatment, as the recommended advice, especially in countries with a high prevalence of HBV infection. What is Known: • There is a variable prevalence of low HBsAb titers measured after the end of chemotherapy in childhood cancer survivors. • There are no universal guidelines for revaccination of these patients. What is New: • This research identified that 86% of childhood cancer survivors treated with standard chemotherapy were seronegative for HBV infection. • A single booster dose HBV vaccine was successful for the majority of patients (90%) to achieve HBsAb titers >10 mIU/ml.

Immunization practices in acute lymphocytic leukemia and post-hematopoietic stem cell transplant in Canadian Pediatric Hematology/Oncology centers

There are no Canadian immunization guidelines for children treated for malignancy. Guidelines do exist for patients who underwent hematopoietic stem cell transplant (HSCT), but they provide broad timeframes for initiating vaccination; there is no standard schedule. The optimal approach to immunization in these populations is unclear. We sought to describe immunization practices at Canadian Pediatric Hematology/Oncology centers. A 43-item online questionnaire was distributed to the 16 programs in the C(17) research network of pediatric hematology/oncology centers to capture information on timing and criteria for immunization of patients with acute lymphocytic leukemia (ALL) and those who have undergone HSCT. At each center, 1-2 physicians or pharmacists completed the survey to reflect center-wide immunization practices. Responses were received from 11/16 (69%) programs; 11 respondents reported on practices for patients with ALL and 9 reported on practices for patients who are post-HSCT. In 5/11 ALL programs (45%) re-immunization is recommended routinely after chemotherapy, starting 3-6 months post-chemotherapy. In HSCT programs, timing of pneumococcal conjugate vaccination (PCV) varied from 3 months post-HSCT (4 programs) to 12 months post-HSCT (4 programs). Live vaccines were administered 24 months post-HSCT in 8/9 programs. All HSCT programs considered graft-versus-host-disease and 7 considered discontinuation of immunosuppression in immunization decisions. Pediatric hematology/oncology programs were divided in regards to re-immunization of patients with ALL post-chemotherapy. After HSCT, timing of PCV administration varied, with 4 programs initiating immunization later than Canadian guidelines recommend (3-9 months post-HSCT). These findings suggest a need to standardize immunization practices in these populations.

[Seroconversion in response to a reinforced primary hepatitis B vaccination in children with cancer]

INTRODUCTION

Immune response against vaccine antigens may be impaired in children with cancer. The aim of this study was to evaluate the seroconversion response against hepatitis B vaccination (HBV) at the time of chemotherapy onset and/or remission in children with cancer.

PATIENTS AND METHOD

Prospective, two-centre, controlled, non-randomised study conducted on children recently diagnosed with cancer, paired with healthy subjects. Cases received HBV at time 0, 1 and 6 months with DNA recombinant HBV at a dose of 20 and 40 μg if < or > than 10 years of age, respectively, at the time of diagnosis for solids tumours and after the remission in case of haematological tumours. Controls received the same schedule, but at of 10 and 20 μg doses, respectively. HBs antibodies were measured in serum samples obtained at 2, 8 and 12 months post-vaccination. Protective titres were defined as > 10 mIU/ml at 8th month of follow up.

RESULTS

A total of 78 children with cancer and 25 healthy controls were analysed at month 8th of follow up. Seroconversion rates in the cancer group reached 26.9%, with no differences by age, gender or type of tumour (P = .13, .29, and .44, respectively). Control group seroconversion was 100% at the 8th month, with P < .0001 compared with the cancer group. At month 12 of follow up, just 31.9% of children with cancer achieved anti-HBs antibodies > 10 mIU/ml.

CONCLUSIONS

Vaccination against hepatitis B with three doses of DNA recombinant vaccine at an increased concentration, administrated at the time of onset of chemotherapy and/or remission provided an insufficient immune response in a majority of children with cancer. More immunogenic vaccines should be evaluated in this special population, such as a third generation, with more immunogenic adjuvants, enhanced schedules at 0, 1, 2, 6 month, evaluation of antibody titres at month 8 and 12h to evaluate the need for further booster doses.

Guidelines on vaccinations in paediatric haematology and oncology patients

OBJECTIVE

Vaccinations are the most important tool to prevent infectious diseases. Chemotherapy-induced immune depression may impact the efficacy of vaccinations in children.

PATIENTS AND METHODS

A panel of experts of the supportive care working group of the Italian Association Paediatric Haematology Oncology (AIEOP) addressed this issue by guidelines on vaccinations in paediatric cancer patients. The literature published between 1980 and 2013 was reviewed.

RESULTS AND CONCLUSION

During intensive chemotherapy, vaccination turned out to be effective for hepatitis A and B, whilst vaccinations with toxoid, protein subunits, or bacterial antigens should be postponed to the less intensive phases, to achieve an adequate immune response. Apart from varicella, the administration of live-attenuated-virus vaccines is not recommended during this phase. Family members should remain on recommended vaccination schedules, including toxoid, inactivated vaccine (also poliomyelitis), and live-attenuated vaccines (varicella, measles, mumps, and rubella). By the time of completion of chemotherapy, insufficient serum antibody levels for vaccine-preventable diseases have been reported, while immunological memory appears to be preserved. Once immunological recovery is completed, usually after 6 months, response to booster or vaccination is generally good and allows patients to be protected and also to contribute to herd immunity.

Protecting pediatric oncology patients from influenza

Influenza is a common respiratory pathogen. Its severity can be unpredictable, but people with chronic illness are at increased risk of severe infection, complications, and death from influenza. This review examines evidence to support various strategies to protect pediatric oncology patients from influenza-related morbidity. Influenza vaccination should be considered standard. Additional evidence-supported measures include antiviral treatment, antiviral prophylaxis, cohorting of patients, and hospital infection control measures. Data from other high-risk populations support the vaccination of family members, double-dose or high-dose vaccination, and the use of barrier methods. These measures have the potential to optimize patient outcomes because there will be fewer treatment interruptions for acute illness. These strategies can also protect patients from prolonged hospitalizations and morbidity related to influenza.

Antibody responses to Hepatitis B and measles-mumps-rubella vaccines in children who received chemotherapy for acute lymphoblastic leukemia

Objective

To evaluate viral vaccine antibody levels in children with acute lymphoblastic leukemia after chemotherapy and after vaccine booster doses.

Methods

Antibody levels against hepatitis B, rubella, measles and mumps vaccine antigens were evaluated in 33 children after completing chemotherapy (before and after vaccine booster doses) and the results were compared to the data of 33 healthy children matched for gender, age and social class.

Results

After chemotherapy, 75.9%, 67.9%, 59.3% and 51.7% of the patients showed low antibody titers that would be unlikely to protect against exposure to measles, rubella, hepatitis B and mumps, respectively. After receiving a vaccine booster dose for these antigens the patients had high antibody levels consistent with potential protection against measles, mumps and hepatitis B, but not against rubella.

Conclusion

Extra doses of measles-mumps-rubella plus hepatitis B vaccines are recommended in acute lymphoblastic leukemia patients submitted to treatment after hematologic recovery. After this, viral vaccine antibody levels should be verified to define the individual's protective status.

Innate immune responses to Stenotrophomonas maltophilia in immunocompromised pediatric patients and the effect of taurolidine

BACKGROUND

Stenotrophomonas maltophilia is an emerging pathogen causing invasive infections in immunocompromised pediatric patients, including neonates and pediatric oncology patients. Information on innate immune responses to S. maltophilia and its potential modulation are scarce.

METHODS

We established an in vitro S. maltophilia whole blood sepsis model and studied the proinflammatory cytokine production of CD14-positive cells by flow cytometry. We compared the cytokine expression of term newborns (n = 13) and healthy adults (n = 10) and investigated in vitro responses of pediatric oncology patients after recovery from neutropenia (n = 10) with healthy adults (n = 10). We further evaluated the immunomodulatory role of the amino-acid derivative taurolidine in our in vitro sepsis model.

RESULTS

Proinflammatory cytokine responses to S. maltophilia were largely diminished in the neonatal population. No remarkable differences were noted for cytokine responses between pediatric oncology patients and healthy controls. Taurolidine inhibited immunoglobulin (IL)-6, IL-8 and tumor necrosis factor-alpha expression in a dose dependent-fashion in both, pediatric oncology patients and healthy controls.

CONCLUSION

Deficient immune responses to S. maltophilia require optimized prevention strategies against infection in immunocompromised patients, including neonates. Taurolidine may be an effective immunomodulatory agent in a clinical setting.

Immunization in special populations

In summary, immunizations in special populations require understanding the underlying disease and how it might affect the immune system's ability to mount an antibody response to vaccines or predispose certain patient populations to developing certain serious infections. There is still a great need for research on the optimal timing of vaccines after transplants, how to assess protection and development of a protective antibody response after immunization, and whether certain groups (eg, HIV) need to be revaccinated after a certain amount of time if their antibody levels decline. In addition, there are limited data on efficacy of the newer vaccines in these special patient populations, which also requires further investigation.

Preventing varicella in children with malignancies: what is the evidence?

PURPOSE OF REVIEW

The prevention of varicella in children with cancer is generally agreed to be an important goal, because of their elevated risk of varicella zoster virus (VZV)-associated morbidity and mortality. However, there is a lack of consensus on the best means of achieving this. Here, we review the existing evidence in relation to postexposure prophylaxis against varicella in this group and summarize data regarding the role of active vaccination.

RECENT FINDINGS

Death from varicella during treatment for cancer is now rare, but VZV disease and its prevention remain significant problems in paediatric oncology practice. Measures to reduce VZV exposure amongst seronegative individuals are often neglected. When exposure is known to have occurred, early administration of varicella zoster immune globulin (VZIG) is generally protective against severe and complicated varicella. However, many centres in the UK and Japan use an oral antiviral agent, aciclovir, in place of VZIG. Published evidence for the efficacy of aciclovir as postexposure prophylaxis (PEP) relates mostly to healthy children, with no controlled studies in the immunocompromised.

SUMMARY

Good evidence already supports the administration of varicella vaccine to healthy susceptible family contacts of children with malignancy, but not to patients themselves. Further data are urgently needed to inform the choice of PEP against VZV in the immunocompromised.

Measles, mumps, and rubella antibody status and response to immunization in children after therapy for acute lymphoblastic leukemia

Seventy-seven patients with acute lymphoblastic leukemia (ALL) who were in complete remission and whose therapies had been stopped for at least 6 months before enrollment in this study were retrospectively analyzed regarding their antibody status for measles, mumps, and rubella, with the aim to demonstrate the seropositivity rate after treatment in the authors' group. Each patient's serum samples were analyzed by enzyme-linked immunosorbent assay (ELISA) method to determine the antibody titers before and after immunization. Measles serology was available in 77 children; 45 (58%) were seronegative. Initial ages of measle-seronegative patients were statistically lower than those of seropositive cases (median 3.29 versus 4.91 years, respectively). Mumps serology was available in 76 children; 36 (47%) were seronegative. Mumps-seropositive cases tended to have more frequent previous history of infection than seronegative cases (55.0% versus 28.6%, respectively, P = .05). Rubella serology was available in 76 children, and 20 (26.3%) were seronegative. It was determined that initial ages of rubella-seronegative patients were statistically lower than those of seropositive cases (median 3.03 versus 4.32 years, respectively). The authors concluded based on the results of their study that at a median of 3.31 years after completion of chemotherapy for ALL, the majority of cases had antibody levels lower than protective values for measles (58.4%); however, these values were 47.3% for mumps and 26.3% for rubella. Seroconversion rates after measles (55%) and mumps vaccination (57.1%) were still low. However, in the available cases, relatively adequate response to rubella vaccination (92.3%) was observed.

Humoral immunity against hepatitis B, tetanus, and diphtheria following chemotherapy for hematologic malignancies: a report and review of literature

Malignancy and its treatment are major causes of secondary immunodeficiency in childhood. The authors investigated the effects of chemotherapy on humoral immunity against hepatitis B, tetanus, and diphtheria in children with hematologic malignancies. The authors recruited 54 patients with hematologic malignancies after the completion of chemotherapy (group A), 25 patients with newly diagnosed hematologic malignancies before initiation of chemotherapy (group B), and 74 healthy controls (group C). All participants had been vaccinated against hepatitis B, tetanus, and diphtheria according to the Iranian national vaccination scheme. Patients in group A achieved protective levels of diphtheria and hepatitis B antibodies significantly less frequently than the other 2 groups and protective levels of tetanus antibody significantly less frequently than group C (P <.05). After controlling for age, the association observed for tetanus lost its significance, but chemotherapy was a significant and independent predictor of failure to achieve protective levels of antibodies against diphtheria (odds ratio [OR] = 7.7, P < .001) and hepatitis B (OR = 3.13, P = .008). These results indicate that chemotherapy has independent adverse effects on vaccine-induced antibody protection against diphtheria and hepatitis B.

Vaccinations in children with cancer

Children with cancer may be immunocompromised as a result of their primary underlying disease and/or the use of prolonged and intensive chemotherapy administered with or without irradiation. The damage to the immune system varies with the age of the patient, the type of cancer, and the intensity of the chemotherapy used to treat it. This review analyses the data regarding the immunogenicity, efficacy, safety and tolerability of the vaccines usually recommended in the first years of life in order to help pediatricians choose the best immunisation programme against vaccine-preventable disease in children with cancer receiving standard-dose chemotherapy. Areas for future research are highlighted because new data are required to be able to draw up evidence-based recommendations that will ensure adequate protection against infectious diseases in such high-risk children.

Humoral immunity to diphtheria, tetanus, measles, and hemophilus influenzae type b in children with acute lymphoblastic leukemia and response to re-vaccination

OBJECTIVE

Loss of immunity to previous vaccination and timing of re-vaccination in children receiving chemotherapy remains controversial. The aim of this study was to investigate the immunity to vaccine preventable diseases in children with acute lymphoblastic leukemia (ALL).

PROCEDURE

Sixty-one patients with ALL and 13 healthy siblings were enrolled. Three study groups included newly diagnosed patients (group 1), patients on maintenance chemotherapy (group 2), and patients that completed chemotherapy (group 3). Blood samples for baseline antibody titers were obtained from all the patients and controls. Patients in group 2 were vaccinated with diphtheria, tetanus, and hemophilus influenzae type b (Hib). Patients in group 3 and controls received the measles vaccine in addition to all the above vaccines. In groups 2 and 3, post-vaccination antibody titers were also obtained.

RESULTS

Patients and controls had no Hib vaccine during primary vaccination. After chemotherapy median antibody levels against diphtheria, tetanus, measles, and Hib were decreased but tetanus antibodies were still at the protective levels. Proportions of the patients with protective levels were 11.1%, 83.3%, 16.7%, and 16.7% for diphtheria, tetanus, Hib, and measles, respectively. Vaccination achieved protective antibody levels in 81%, 100%, 89.5%, and 70% of the patients for diphtheria, tetanus, Hib, and measles, respectively. Vaccine responses during maintenance were also satisfying.

CONCLUSION

We recommend re-vaccination after 3 months of cessation of chemotherapy. Administration of Hib vaccine may be beneficial after the first 3 months of maintenance chemotherapy especially in children with no primary vaccination followed by a second booster dose after cessation of therapy to increase immunity.

Immunization after the elective end of antineoplastic chemotherapy in children

The aim of the present commentary is to discuss the multifaceted topic of vaccinations after treatment for cancer in the pediatric age. Publications in this field reveal conflicting data and opinions; no evidence-based guidelines currently exist. However, in spite of several discrepancies some commonly accepted information and conclusions exist. Efforts to find a common strategy of re-immunization should be directed towards setting up prospective studies on sufficient numbers of patients to obtain statistically relevant end points.

Changes in acetylcholinesterase (AchE) activity in lymphocytes and whole blood in acute lymphoblastic leukemia patients

BACKGROUND

Acute lymphoblastic leukemia (ALL) is a type of cancer that affects lymphocytes and it is the most common form of cancer in children. Acetylcholinesterase (AChE) is well known as having non-cholinergic functions and has been detected in the blood and plasma of humans including in lymphocytes. Thus, we investigated whole blood and lymphocyte AChE activity in patients with ALL.

METHODS

This study was performed on 72 children with ALL divided into 4 groups: newly diagnosed, remission induction, remission maintenance and out-of-treatment and one control group of 50 healthy subjects. We determined AChE activity in whole blood and lymphocytes of these patients.

RESULTS

Results demonstrated that whole blood AChE activity was enhanced in the newly diagnosed group and reduced in the remission induction and remission maintenance groups in relation to the control group. For lymphocyte AChE activity we found an increase in the newly diagnosed group and a decrease in the remission induction group in relation to the control.

CONCLUSIONS

These results suggest that AChE activity was altered in ALL patients. This fact may be related with the essential role played by AChE in the development of hematological disease and its contribution to the regulation of immune function.

L-Asparaginase: A Promising Chemotherapeutic Agent

This article comprises detailed information about L-asparaginase, encompassing topics such as microbial and plant sources of L-asparaginase, treatment with L-asparaginase, mechanism of action of L-asparaginase, production, purification, properties, expression and characteristics of l-asparaginase along with information about studies on the structure of L-asparaginase. Although L-asparaginase has been reviewed by Savitri and Azmi (2003), our effort has been to include recent and updated information about the enzyme covering new aspects such as structural modification and immobilization of L-asparaginase, recombinant L-asparaginase, resistance to L-asparaginase, methods of assay of L-asparagine and L-asparaginase activity using the biosensor approach, L-asparaginase activity in soil and the factors affecting it. Also, side-effects of L-asparaginase treatment in acute lymphoblastic leukemia (ALL) have been discussed in the current review. L-asparaginase has been and is still one of the most widely studied therapeutic enzymes by researchers and scientists worldwide.

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.

Dendritic cell regeneration in the bone marrow of children treated for acute lymphoblastic leukaemia

Dendritic cells (DC) play a pivotal role in coordinating functions of the immune system. Little is known about DC levels in the bone marrow (BM) of patients receiving cytostatic treatment. We investigated DC levels by flow cytometry in BM at diagnosis, during and post-treatment in 76 children with acute lymphoblastic leukaemia (ALL). The levels of both plasmacytoid DC (pDC) and myeloid DC (mDC) were profoundly reduced at diagnosis. However, the levels of pDC and mDC were significantly higher in T-precursor ALL patients when compared with B-precursor ALL patient group (P = 0.044 and 0.041 respectively). Both subsets normalized in both standard-risk (SR) and high-risk patients after the end of induction at day 50. Patients with minimal residual disease (MRD) at day 50 had significantly higher pDC levels than MRD-negative patients (P = 0.021). In B-precursor SR ALL patients, mDC levels but not pDC levels decreased during prolonged maintenance treatment, remaining reduced at the end of treatment (P = 0.032) and at 6 months post-treatment (P = 0.028). In conclusion, levels of DC in BM normalize quickly in children treated for ALL. Long-term treatment may more profoundly affect mDC subset, which shows reduced levels several months after treatment.

Unexpected protection from infection by two booster hepatitis B virus vaccination in children with acute lymphoblastic leukemia

The protective power of two booster dose vaccination against hepatitis B virus (HBV) infection has not been previously studied in patients with acute lymphoblastic leukemia (ALL) who remained unresponsive to immunization. The aim of this study was to determine the HBV infection rate in vaccinated and unvaccinated patients with or without seroconversion and to compare these groups in respect to HBV infection rate. The study group included 111 male and 85 female ALL patients with a mean age of 6.23+/-4.10 years. Patients were divided into three groups as follows: Group 1 included 82 patients who were vaccinated during maintenance chemotherapy, Group 2 included 87 unvaccinated patients, and Group 3 included 27 patients who were vaccinated prior to the diagnosis of ALL. Seroconversion was obtained in 35.4% (29/82) of patients in Group 1. The incidence of HBV infection was significantly lower in Group 1 (4/82, 4.8%) than in Group 2 (25/87, 28.7%). When we compared only the seronegative patients in Group 1 with Group 2 in respect to HBV infection rate, Group 1 still had a significantly lower HBV infection rate than Group 2 (7.5% versus 28.7%) (p<0.001). No patients in Group 3 (n=27) had HBV infection. In addition to the seroconversion level, infection rate is also important in the evaluation of the effectiveness of vaccination. Our study results suggest that a high protective role of HBV vaccination was also observed in non-seroconversion ALL patients. The effect of cellular immunity on the protection against infection should also be investigated in such patients with further studies.

Loss of antibodies and response to (re-)vaccination in children after treatment for acute lymphocytic leukemia: a systematic review

Intensified chemotherapy regimens resulting in improved survival of children with acute lymphocytic leukemia (ALL) lead to concerns about therapy-induced immune damage reflected by the loss of protection of previous immunizations and the efficacy of (re-)vaccination. The severity of secondary immunodeficiency, however, is not clear and knowledge is based on a limited number of studies. We performed a systematic review on literature concerning vaccination data of children with ALL published since 1980. Eight studies fulfilled the inclusion criteria. Regarding antibody titers after treatment, the number of children who had preserved the defined protection level for antibodies differed widely, ranging from 17 to 98% for diphtheria, 27 to 82% for Bordetella pertussis, 20 to 98% for tetanus, 62 to 100% for poliomyelitis, 35 to 100% for Haemophilus influenzae type B (HiB), 29 to 92% for mumps, 29 to 60% for measles and 72 to 92% for rubella. Most patients however responded to revaccination, demonstrating immunological recovery. Although the designs and results of the included studies varied widely, it can be concluded that cytostatic therapy for ALL in children results in a temporarily reduction of specific antibody levels. Memory is preserved but revaccination may be warranted. This is the first systematic review and the best possible current approximation of chemotherapy-induced immune damage in children after ALL treatment.