Safety and Efficacy of Re-Immunization with Inactivated Vaccines in Multiple Myeloma Patients on Lenalidomide Maintenance Following Autologous Hematopoietic Stem Cell Transplantation (Auto HCT)

Introduction: Lenalidomide maintenance (LM) is the standard of care for multiple myeloma (MM) patients after Auto HCT to prolong progression free survival. Although CDC guidelines recommend vaccination starting 12 months after HCT, there is varying practice amongst institutions regarding revaccination in patients on maintenance therapy, with some not vaccinating at all. Due to decreased vaccine rates among the general population causing decreases in herd immunity, we aim to establish the safety and efficacy of revaccinating patients on LM. Methods: We retrospectively identified MM patients from the institutional registry who received first Auto HCT within one year of diagnosis, were transplanted in 2013, and were on LM at time of re-immunization. Vaccine responses were determined based on comparison of pre- and post- vaccination titers. We then classified patients as responders, non-responders, immune by pre-vaccination titer, and not evaluable due to missing data (not receiving vaccine or missing either pre or post-vaccination titers) and used descriptive statistics to summarize the results for each vaccine. Adverse events due to vaccination were retrospectively collected. Results: 24 patients met inclusion criteria (median age, 57 years; range, 35-71; 50% males). Median time to vaccination was 12.6 months (range 11.9-16.8) after Auto HCT. 23 patients received the Haemophilus influenzae type b (Hib) vaccine and all completed the series per CDC guidelines. With 25% starting immune and 13% not evaluable, 58% responded (95% of evaluable) (Figure 1). Pneumococcal vaccination with Prevnar 13 occurred in 23 and all completed the series. All patients had lost their immunity prior to vaccination, but 54% responded to the vaccine (59% of evaluable). 23 patients received the Polio vaccine with 21 completing the full series. With 63% retaining immunity, 29% responded to the inactivated polio vaccine (100% of evaluable). Only 9 patients completed the full Tdap vaccine series, but 22 received at least 1 dose. Tetanus, diphtheria, and pertussis had 63%, 75%, and 71% responders (94, 90, 85% of evaluable), with 21%, 0% and 4% starting immune, respectively. Fewer patients received and completed the Hepatitis A and B vaccines with 15 patients receiving the Hepatitis A vaccine as single agent vaccine or as combined Twinrix (8 completing), and 16 patients receiving the Hepatitis B vaccine as either single agent or combined Twinrix (7 completing). Responses occurred in 47% and 53% (64 & 67% of evaluable), with 20% and 13% starting immune, respectively. No patients had any adverse events. These response rates are consistent with reports in patients notreceiving LM and support preliminary data that lenalidomide may augment vaccine responses. Conclusions: Re-immunization with inactivated vaccines in patients on LM is both safe and effective, offering this population immunity to vaccine preventable diseases.