Improved serologic responses to DTaP over Tdap vaccination in adult hematopoietic cell transplant recipients.

BACKGROUND: Hematopoietic cell transplantation (HCT) recipients have reduced antibody titers to tetanus, diphtheria, and pertussis. Tdap is approved for revaccinating adult HCT recipients in the United States, whereas DTaP is not approved in this population. To our knowledge, no studies to date have compared responses to DTaP versus Tdap in adult HCT patients. We conducted a retrospective study comparing responses to DTaP versus Tdap vaccines in otherwise similar adult HCT patients in order to determine if one of these vaccines elicits superior antibody responses. METHODS: We evaluated 43 allogeneic and autologous transplant recipients as a combined cohort and as separate subsets for vaccine specific antibody titers and proportion of strong vaccine responders. Subset analysis focused on the autologous transplant recipients. RESULTS: Higher median antibody titers were found to all vaccine components among DTaP recipients (diphtheria p = .021, pertussis p = .020, tetanus p = .007). DTaP recipients also had more strong responders to diphtheria and pertussis (diphtheria p = .002, pertussis p = .006). Among the autologous HCT recipient subset, there were more strong responders to diphtheria (p = .036). CONCLUSIONS: Our data shows that post-HCT vaccination with DTaP leads to higher antibody titers and more strong responders, which suggests that DTaP is more effective than Tdap in HCT recipients.

Gastrointestinal toxicity of high-dose melphalan in autologous hematopoietic stem cell transplantation: identification of risk factors and a benchmark for experimental therapies.

Gastrointestinal side effects are the dose-limiting toxicity of high-dose melphalan (HDM) in autologous hematopoietic stem-cell transplantation, but there are limited contemporary data on the incidence and severity of gastrointestinal toxicity associated with this regimen. We retrospectively studied 100 consecutive patients who received HDM alone or in combination with other conditioning agents. Patients had a median age of 56 (range 20-73); underlying diseases were myeloma (42%), lymphoma (42%), or amyloidosis (16%) and melphalan dosages were 200 (40%), 140 (59%), or 100 mg/m2 (1%). Ninety-seven percent of patients experienced diarrhea with a range of 1-18 bowel movements per day, 88% developed nausea, and 60% experienced vomiting. Abdominal CT scans rarely altered patient management, but stool studies were useful in identifying a treatable infectious source. Grade ≥ 2 diarrhea was associated with longer duration of diarrhea, longer length of stay, worse hypoalbuminemia, higher use of antibiotics, abdominal imaging, electrolyte repletions, and anti-diarrheal agents. Risk factors for severe diarrhea were female sex, melphalan dose, age > 50, creatinine clearance < 60 ml/min, and having a plasma cell neoplasm as opposed to lymphoma. Female sex was also associated with more severe nausea and vomiting. In summary, diarrhea remains an important toxicity of HDM and novel therapies for chemotherapy-induced diarrhea for patients undergoing stem-cell transplantation are needed. Grade 2 or higher diarrhea is associated with significant clinical consequences and should be used as the primary endpoint in prospective clinical trials.