Chemotherapy-induced loss of protective antibody titers against commonest vaccine-preventable infections in patients with pediatric Hodgkin lymphoma

Introduction Loss of protective humoral immunity after cancer treatment has previously been recognized. Magnitude of this side effect depends on type of neoplasm, as well as the treatment strength and duration. The mechanism of loss is multifactorial; it involves depletion of memory B- and plasma cells, and their antibody production capacity [1]. It was demonstrated that after cessation of therapy for acute lymphoblastic leukemia (ALL), serum immunoglobulin (IgG) levels, which is a reflection of B cell function, will recover around 6 months off therapy, although it still may be suboptimal [2] [3]. Several studies have been published, testing only specific vaccine titers in isolated subsets of pediatric cancer patients, with somewhat inconclusive results about whether patients should be tested and revaccinated for preventable diseases[4] [5]. The pattern of loss of protective humoral immunity in pediatric Hodgkin lymphoma patients remains uncharacterized. We evaluated spectrum of loss of vaccination titers in pediatric HL patients, in order to determine if standardized evaluation and re-vaccination protocols should be instituted.

Methods Retrospective chart review of 156 HL and ALL patients treated at Cleveland Clinic Children’s Hospital (CCCH), who were off therapy ≥ 6 months. Confirmation of vaccination per CDC schedule prior to diagnosis was made through EMR. Patients who had one or more serum antibody measurement against Hepatitis B, Measles, Mumps, Rubella, Varicella, Diphtheria or Tetanus, per CCCH laboratory reference standards were noted. Patients with pre-existing PID; treatment with IVIG; immunosuppressant therapy for another diagnosis; disease progression requiring ASCT, were excluded.

Results Thirty six HL patients were identified. Humoral immunity testing was performed in 16 patients (44%). The loss or equivocal titers for the following vaccines were noted; hepatitis B (13/16=81%), measles (7/16=44%), mumps (3/16=19%), rubella (2/16=13%), varicella (8/16=50%), diphtheria (5/16=31%), tetanus (2/16=13%). The most drastic changes were seen in HL patients treated on high-risk protocols. Results were similar to the ones seen in ALL patients.

Conclusion Results of this pilot project suggest that routine evaluation of antibody titers post-treatment in pediatric HL patients should be implemented uniformly as there are marked decline in protective IgG levels. Implementing a standardized re-vaccination schedule for all HL patients off-treatment will ensure seroprotection against common preventable diseases.

Conflict of Interest:

none

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