BACKGROUND The lymphocyte-depleting antibody alemtuzumab is a highly effective treatment for relapsing-remitting multiple sclerosis (RRMS); however, 50% of patients develop novel autoimmunity after treatment. Most at risk are individuals who reconstitute their T cell pool by proliferating residual cells, rather than producing new T cells in the thymus, raising the possibility that autoimmunity might be prevented by increasing thymopoiesis. Keratinocyte growth factor (palifermin) promotes thymopoiesis in nonhuman primates.METHODS Following a dose tolerability substudy, individuals with RRMS (duration ≤10 years; expanded disability status scale ≤5.0, with ≥2 relapses in the previous 2 years) were randomized to placebo or 180 μg/kg/d palifermin, given for 3 days immediately before and after each cycle of alemtuzumab, with repeat doses at month 1 (M1) and M3. The interim primary endpoint was naive CD4+ T cell count at M6. Exploratory endpoints included number of recent thymic emigrants (RTEs) and signal joint T cell receptor excision circles/ml (sjTRECs/ml) of blood. The trial’s primary endpoint was incidence of autoimmunity at M30.RESULTS At M6, individuals receiving palifermin had fewer naive CD4+ T cells (2.229 × 107/l vs. 7.733 × 107/l; P = 0.007), RTEs (16% vs. 34%), and sjTRECs/ml (1100 vs. 3396), leading to protocol-defined termination of recruitment. No difference was observed in the rate of autoimmunity between the 2 groups.CONCLUSION In contrast with animal studies, palifermin reduced thymopoiesis in our patients. These results offer a note of caution to those using palifermin to promote thymopoiesis in other settings, particularly in the oncology/hematology setting, where alemtuzumab is often used as part of the conditioning regime.TRIAL REGISTRATION ClinicalTrials.gov NCT01712945.FUNDING MRC and Moulton Charitable Trust.
Alasdair J. Coles, Laura Azzopardi, Onajite Kousin-Ezewu, Harpreet Kaur Mullay, Sara A.J. Thompson, Lorna Jarvis, Jessica Davies, Sarah Howlett, Daniel Rainbow, Judith Babar, Timothy J. Sadler, J. William L. Brown, Edward Needham, Karen May, Zoya G. Georgieva, Adam E. Handel, Stefano Maio, Mary Deadman, Ioanna Rota, Georg Holländer, Sarah Dawson, David Jayne, Ruth Seggewiss-Bernhardt, Daniel C. Douek, John D. Isaacs, Joanne L. Jones
Guidelines: The Editorial Board will only consider letters that we deem relevant and of interest to our readers. We will not post data that have not been subjected to peer review, nor will we post letters that are essentially a reiteration of another letter. All accepted letters will be posted on our website within one week of acceptance. We reserve the right to edit any letter for length, content, and clarity. Authors of all accepted letters will be asked to preview any changes. Authors will be notified by e-mail if their letters were not accepted. As this is a final decision, no appeals will be considered.
Specific requirements: All letters must be 400 words or fewer. You may enter the letter as plain text or HTML. The author's name and e-mail address are required, and will be posted with the letter. All possible conflicts of interest must be noted, even if they are not posted. If you wish to include a figure (keep in mind that non-peer-reviewed data will not be posted), please contact the editors directly at firstname.lastname@example.org.