Immunization after the elective end of antineoplastic chemotherapy in children

Humoral profiling of pediatric patients with cancer reveals robust immunity following anti-SARS-CoV-2 vaccination superior to natural infection

BACKGROUND

Pediatric patients with cancer infected with COVID-19 may be at higher risk of severe disease and may be unable to mount an adequate response to the virus due to compromised immunity secondary to their cancer therapy.

PROCEDURE

This study presents immunologic analyses of 20 pediatric patients with cancer, on active chemotherapy or having previously received chemotherapy, and measures their immunoglobulin titers and activation of cellular immunity response to acute SARS-CoV-2 infection and COVID-19 vaccination compared with healthy pediatric controls.

RESULTS

Forty-three patients were enrolled, of which 10 were actively receiving chemotherapy, 10 had previously received chemotherapy, and 23 were healthy controls. Pediatric patients with cancer had similar immunoglobulin titers, antibody binding capacity, and effector function assay activity after vaccination against COVID-19 compared with healthy controls, though more variability in response was noted in the cohort actively receiving chemotherapy. Compared with acute infection, vaccination against COVID-19 produced superior immunoglobulin responses, particularly IgA1, IgG1, and IgG3, and elicited superior binding capacity and effector function in children with cancer and healthy controls.

CONCLUSIONS

Pediatric patients receiving chemotherapy and those who had previously received chemotherapy had adequate immune activation after both vaccination and acute infection compared to healthy pediatric controls, although there was a demonstrated variability in response for the patients on active chemotherapy. Vaccination against COVID-19 produced superior immune responses compared to acute SARS-CoV-2 infection in pediatric patients with cancer and healthy children, underscoring the importance of vaccination even in previously infected individuals.

Assessment of Humoral Immunity to Measles Virus in Cancer Survivor Children after Chemotherapy: A Case-Control Study

This case-control study was conducted to determine the antibody titer against the measles virus in childhood cancer survivors' post-chemotherapy treatment to determine the patient's immune status against the measles virus. We enrolled 38 children who were in complete remission and whose treatments had been stopped for at least 3 months and 38 age and sex-matched healthy controls. We analyzed the medical records of the cancer survivors, and each study participant's serum sample was analyzed by the ELISA method to determine the antibody titer against measles. The cancer survivors had significantly lower measles antibody titers than the healthy control participants, and 78.9% of cancer survivors were unprotected (seronegative) compared to 7.9% in healthy controls. After multivariate analysis, there was no statistically significant factor associated with loss of protective humoral immunity against measles. These results underline the need for post-chemotherapy measles antibody testing and revaccination of seronegative survivors.

Vaccination in pediatric cancer survivors: Vaccination rates, immune status, and knowledge regarding compliance

BACKGROUND

Vaccination recommendations for childhood cancer survivors are ambiguous. Limited data exist on vaccination rates and patient/caregiver knowledge of vaccination postchemotherapy.

PROCEDURE

A single-institution study of childhood cancer survivors treated from 1996 to 2018. Study included a retrospective chart review assessing patient's vaccination status, survey of patient's/caregiver's knowledge/beliefs regarding vaccination postchemotherapy, and assessment of immunoglobulin titers.

RESULTS

A total of 120 patient charts were included. Vaccination records were available for 82% (98/120) of patients, 57% (56/98) were up to date with vaccinations before chemotherapy, and 83% (81/98) received vaccinations after chemotherapy. Children who resumed vaccination postchemotherapy were younger at cancer diagnosis compared to those who did not resume vaccination (2 vs 4 years, P < .02). Median time since chemotherapy was higher in vaccinated versus unvaccinated patients (107 vs 60 months, P < .02). Immunoglobulin titers were assessed in 27 patients, and 74% (20/27) were not immune to one or more infections tested. Lack of immunity to pneumococcal strains was the most common. There was no difference in median age at diagnosis or time since chemotherapy completion in immune versus nonimmune patients. In 33 surveyed patients/caregivers, 33% (11/33) were not advised about resuming vaccinations postchemotherapy. Over one-third (12/33) of respondents were concerned about vaccination safety after chemotherapy, although 88% (29/33) agreed they would vaccinate if recommended by their pediatrician/pediatric oncologist.

CONCLUSIONS

Most childhood cancer survivors resume vaccinations postchemotherapy. Considerable variability exists in vaccination timing after chemotherapy. Pediatric oncologists play a central role in educating patients/pediatricians about vaccination recommendations postchemotherapy.

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.

Postchemotherapy Immunization Practices for Non-HSCT Pediatric Oncology Patients

Pediatric oncology patients treated with antineoplastic therapy have impaired immune systems that lead to loss of protective antibodies. They require reimmunization to protect against vaccine-preventable diseases. There are a paucity of studies on the clinical practice of pediatric oncologists and the available recommendations are heterogenous. This study describes current reimmunization practices among pediatric oncologists. We surveyed the Children's Oncology Group (COG)-identified principle investigators to capture clinical practices among pediatric oncologists within their institutions regarding reimmunization of non-hematopoietic stem cell transplantation patients. The majority of respondents did not routinely assess vaccine-related immune status; those who did most frequently assessed 6 months after cessation of therapies. Methods of assessment included type of therapy received, vaccine titers, and absolute lymphocyte counts. Providers from smaller institutions were more likely to check vaccine titers than those from larger institutions. More than half of the surveyed institutions did not have standardized guidelines available for practitioners. There are variations in reimmunization practices among pediatric oncologists despite available guidelines on recommended schedules. Further research is needed to identify the safest and most cost-effective way to insure immunity to infectious disease after the treatment of childhood cancer.

Late Infection-Related Mortality in Asplenic Survivors of Childhood Cancer: A Report From the Childhood Cancer Survivor Study

Purpose Infection-related outcomes associated with asplenia or impaired splenic function in survivors of childhood cancer remains understudied. Methods Late infection-related mortality was evaluated in 20,026 5-year survivors of childhood cancer (diagnosed < 21 years of age from 1970 to 1999; median age at diagnosis, 7.0 years [range, 0 to 20 years]; median follow-up, 26 years [range, 5 to 44 years]) using cumulative incidence and piecewise-exponential regression models to estimate adjusted relative rates (RRs). Splenic radiation was approximated using average dose (direct and/or indirect) to the left upper quadrant of the abdomen (hereafter, referred to as splenic radiation). Results Within 5 years of diagnosis, 1,354 survivors (6.8%) had a splenectomy and 9,442 (46%) had splenic radiation without splenectomy. With 62 deaths, the cumulative incidence of infection-related late mortality was 1.5% (95% CI, 0.7% to 2.2%) at 35 years after splenectomy and 0.6% (95% CI, 0.4% to 0.8%) after splenic radiation. Splenectomy (RR, 7.7; 95% CI, 3.1 to 19.1) was independently associated with late infection-related mortality. Splenic radiation was associated with increasing risk for late infection-related mortality in a dose-response relationship (0.1 to 9.9 Gy: RR, 2.0; 95% CI, 0.9 to 4.5; 10 to 19.9 Gy: RR, 5.5; 95% CI, 1.9 to 15.4; ≥ 20 Gy: RR, 6.0; 95% CI, 1.8 to 20.2). High-dose alkylator chemotherapy exposure was also independently associated with an increased risk of infection-related mortality (RR, 1.9; 95% CI, 1.1 to 3.4). Conclusion Splenectomy and splenic radiation significantly increase risk for late infection-related mortality. Even low- to intermediate-dose radiation exposure confers increased risk, suggesting that the spleen is highly radiosensitive. These findings should inform long-term follow-up guidelines for survivors of childhood cancer and should lead clinicians to avoid or reduce radiation exposure involving the spleen whenever possible.

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.

Human Papillomavirus Vaccination Rates in Young Cancer Survivors

Purpose

Cancer survivors are at high risk for human papillomavirus (HPV)-related morbidities; we estimated the prevalence of HPV vaccine initiation in cancer survivors versus the US population and examined predictors of noninitiation.

Methods

Participants included 982 cancer survivors (9 to 26 years of age; 1 to 5 years postcompletion of therapy); we assessed HPV vaccine initiation, sociodemographic and clinical characteristics, and vaccine-specific health beliefs; age-, sex-, and year-matched US population comparisons were from the National Immunization Survey-Teen and the National Health Interview Survey (2012-2015).

Results

The mean age at the time of the study was 16.3 ± 4.7 years; the mean time off therapy was 2.7 ± 1.2 years; participants were 55% male and 66% non-Hispanic white; 59% had leukemia/lymphoma. Vaccine initiation rates were significantly lower in cancer survivors versus the general population (23.8%; 95% CI, 20.6% to 27.0% v 40.5%; 95% CI, 40.2% to 40.7%; P < .001); survivors were more likely to be HPV vaccine-naïve than general population peers (odds ratio [OR], 1.72; 95% CI, 1.41 to 2.09; P < .001). Initiation in adolescent survivors (ages 13 to 17 years) was 22.0% (95% CI, 17.3% to 26.7%), significantly lower than population peers (42.5%; 95% CI, 42.2% to 42.8%; P < .001). Initiation in young adult survivors and peers (ages 18 to 26 years) was comparably low (25.3%; 95% CI, 20.9% to 29.7% v 24.2%; 95% CI, 23.6% to 24.9%). Predictors of noninitiation included lack of provider recommendation (OR, 10.8; 95% CI, 6.5 to 18.0; P < .001), survivors' perceived lack of insurance coverage for HPV vaccine (OR, 6.6; 95% CI, 3.9 to 11.0; P < .001), male sex (OR, 2.9; 95% CI, 1.7 to 4.8; P < .001), endorsement of vaccine-related barriers (OR, 2.7; 95% CI, 1.6 to 4.6; P < .001), and younger age (9 to 12 years; OR, 3.7; 95% CI, 1.8-7.6; P < .001; comparison, 13 to 17 years).

Conclusion

HPV vaccine initiation rates in cancer survivors are low. Lack of provider recommendation and barriers to vaccine receipt should be targeted in vaccine promotion efforts.

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.

Impact of treatment reduction for childhood acute lymphoblastic leukemia on serum immunoglobulins and antibodies against vaccine-preventable diseases

BACKGROUND

The consequences of current intensive chemotherapy for childhood acute lymphoblastic leukemia (ALL) for immune defense are a matter of concern. The purpose of this study was to examine the effect of reduced compared with intensive (conventional) ALL chemotherapy on serum immunoglobulin levels and specific antibody concentrations against vaccine-preventable diseases.

PROCEDURE

Patients treated according to Dutch Childhood Oncology Group ALL 10 protocol were stratified by minimal residual disease to receive reduced (standard risk; SR) or intensive (medium risk; MR) intensification/maintenance treatment. Between November 2004 and July 2009 we compared serum immunoglobulins of 110 patients and specific antibodies against diphtheria toxin, tetanus toxin, and Bordetella pertussis antigens of 41 patients of SR and MR groups during chemotherapy.

RESULTS

Immunoglobulin levels showed significantly different patterns between the SR and MR groups. In the MR group IgG, IgA, and IgM levels decreased towards the end of intensive treatment; in the SR group IgG levels increased while IgA and IgM stabilized. In both groups IgM and IgG levels were most affected. Specific antibody levels against vaccine-preventable diseases decreased in both groups, but more profound in MR group.

CONCLUSIONS

Although reduced chemotherapy is beneficial for immunoglobulin level recovery and might prevent susceptibility for infections, specific antibodies remain decreased.

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.

Survivors of childhood cancer: an Australian audit of vaccination status after treatment

BACKGROUND

Survivors of childhood and adolescent cancer are at risk of vaccine preventable diseases and are recommended to receive booster vaccinations post-chemotherapy. The aim of this study was to describe the compliance of post-chemotherapy revaccination of childhood cancer survivors relative to current Australian guidelines.

PROCEDURES

A multi-faceted retrospective review of childhood cancer survivors at the Royal Children's Hospital, Melbourne, Australia was undertaken. Immunisation status was reviewed through four sources: (1) hospital records; (2) telephone survey of consenting participants; (3) Australian Childhood Immunization Register (ACIR); and (4) family practitioners immunisation records. Participants were 0-18 years, and at least 6 months post-treatment for their cancer.

RESULTS

The study was conducted between March and September 2006. Eighty-nine patients with a median age at diagnosis of 5.3 years were included, 56% of patients had a diagnosis of leukaemia and 44% solid tumours. The median duration since completion of therapy was 3.1 years. Reviewing all sources, 39% (35/89) of participants had no evidence of booster vaccinations post-completion of therapy. Younger age (P = 0.001), and those diagnosed with leukaemia (P = 0.04) were more likely to have received at least one booster vaccine. Forty-seven percent (42/89) had received at least one influenza vaccination.

CONCLUSION

This study highlights poor compliance with current guidelines for re-vaccination in survivors of childhood and adolescent cancer. More evidence is required and these re-vaccination guidelines need to take into account treatment intensity. Multi-component strategies are essential to ensure protection from vaccine preventable diseases in this population.

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