Immune cell subsets
In the fingolimod-naive cohort, changes in immune cell subsets were expected and characteristic. Overall CD4+ count declined from baseline to month 6, and the decrease was “driven primarily by a decline in CD4+ naive T cells and CD4+ central memory T cells.” CD4+ effector memory cells, CD4+ Th1 cells, CD4+ Th2 cells, and CD4+ Th17 cells were less affected. “The effector cells do not have an expression of CCR7 [C-C chemokine receptor type 7] so they tend not to hone to the lymph nodes anyway,” Dr. Cree said.
CD8+ cells followed a similar pattern. “The overall count goes down, but perhaps not as much as with the CD4+ cells. The central memory and naive cells are affected a little bit more than the effector memory cells,” Dr. Cree said. “Then we see a comparable pattern with B cells. The absolute CD19+ counts go down. They’re driven by a decline in the naive cells. ... with less of a decline in memory cells and almost no decline in regulatory cells.”
Among innate immune cells, monocytes increased slightly, neutrophils declined, as expected, and natural killer cells declined slightly.
“When you turn your attention to ... those patients who have been on fingolimod, you do not see these changes for the lymphocytes,” Dr. Cree said. “Those lymphocytes are already sequestered, and we are really not seeing much of a change over time at all.”
A measure of CNS injury
In the treatment-naive cohort, serum neurofilament light chain (NfL) declined, but this measure did not change by much in the treatment-experienced cohort.
Among patients already on fingolimod, the serum NfL reduction “that would be anticipated as a therapeutic benefit from fingolimod is already being realized,” he said.
The serum NfL levels in the treatment-naive cohort at 6 months were similar to those of the treatment-experienced cohort at baseline, which indicates that “the impact of fingolimod in reducing circulating neurofilament – a marker of central nervous system injury – is seen within 6 months of treatment and likely persists as patients continue on fingolimod therapy,” Dr. Cree said.
Baseline anti-JCV antibody index was about the same for the treatment-naive and treatment-experienced cohorts (1.28 vs. 1.39, respectively), and this measure did not meaningfully change over 6 months in either cohort.
No new adverse events were identified in this interim analysis. Most common adverse events occurred more frequently in the treatment-naive cohort than in the treatment-experienced cohort, including headache (7.2% vs. 1.9%), upper respiratory tract infection (4.2% vs. 1.9%), pain in extremity (4.2% vs. 1.4%), lymphopenia (4.8% vs. 0.5%), anxiety (3.6% vs. 1.4%), fatigue (3.6% vs. 1.4%), nausea (3.0% vs. 0.9%), dizziness (3.0% vs. 0.5%), hypoesthesia (3.0% vs. 0.5%), and tremor (3.0% vs. 0%). An exception was falls, which occurred in 3.0% of the treatment-naive cohort and 4.6% of the treatment-experienced cohort.
Serious adverse events were about equal between the two groups (4.2% of the treatment-naive group and 5.1% of the treatment-experienced group), and adverse events leading to treatment discontinuation were more common in the fingolimod-naive cohort (10.2% vs. 5.6%).
Novartis funded the study, and four of the authors are Novartis employees. Dr. Cree disclosed consulting fees from Novartis and other pharmaceutical companies. His coauthors disclosed consulting fees, speaking fees, research support, and serving on advisory boards for pharmaceutical companies, including Novartis.
SOURCE: Mao-Draayer Y et al. CMSC 2019. Abstract DXM03.