Therapy Transition from Fingolimod to Oral Cladribine: Eliminating the Washout

Background: When planning care for patients with multiple sclerosis (MS), clinicians often balance the need for a timely transition to a new treatment and the potentially lasting immunologic effects of previous treatments. Clinical trials are designed to limit the carryover of previous medications when evaluating current therapy. The extent of the washout leaves patients at risk for relapses. In clinical practice, these washouts are often shortened to prevent relapse, but there is a lack of data to formally guide the optimal timeframe. In addition, the cladribine labelling recommends waiting to initiate cladribine until the absolute lymphocyte count (ALC) is within normal limits. For patients receiving fingolimod, this may result in a prolonged washout period and may increase the risk of relapse or even rebound disease activity.

Objectives: To evaluate the safety of transitioning from fingolimod to cladribine with a transition duration of 0 to 3 days on absolute lymphocyte count during year 1 of oral cladribine therapy.

Methods: Single center, retrospective study of ALC in MS patients transitioning from fingolimod to cladribine during year 1 and prior to starting year 2 of treatment.

Results: A total of 16 patients were identified. Baseline laboratory results were reflective of lymphocyte sequestration due to fingolimod therapy, mean ALC 0.48, range (0.11-2). At month 11, each patient met or exceeded the threshold ALC value of 0.8 x 10³ lymphocytes/uL recommended in the cladribine labelling prior to the start of year 2.

Conclusions: From a safety perspective, a washout period when switching from fingolimod to cladribine appears to be unnecessary. Despite the lack of washout, this transition did not adversely affect the reconstitution of lymphocytes and did not result in worsening lymphopenia from baseline.