Introduction
Immunosequencing is an emerging clinical test to identify, quantify, and track dominant T-cell clones in cutaneous T-cell lymphoma (CTCL). Previous immunosequencing studies found tumor clone frequency (TCF), as defined by the percentage of the dominant malignant T-cell clone among other T cells, as a prognostic factor for patients with early-stage mycosis fungoides (MF).
Objective
To evaluate the real-life clinical applications of immunosequencing, we analyzed the results of T-cell receptor immunosequencing in our cohort and correlated them with each patient's clinical presentation.
Methods
A retrospective chart review of MF immunosequencing data was performed from 2019 to 2024. 103 patients with MF were included with 75 patients (72.8%) with early-stage disease. ClonoSEQ, an immunosequencing assay approved for clinical use, was used to identify dominant clones in skin biopsies.
Results
Review of immunosequencing data found 23.6% of biopsies did not have a dominant clone identified while 53.9% of biopsies had one dominant clone and 22.5% had multiple dominant clones. Of the multiple dominant clones, 26% were single base mutated intraclonal variants, and their emergence coincided with disease progression.
Additionally, the average TCF percent change throughout a patient's clinical course was 35.9%. A similar percent change was observed among biopsies taken on the same day that differed by anatomical location (37.58%). Most cases demonstrated a >20% change in TCF in both scenarios (70.73% throughout clinical course; 74.19% by anatomical location).
Conclusion
Overall, we found a large degree of intra- and inter-patient variability among the distribution and frequency of dominant malignant T-cell clones in our cohort. Our findings highlight the heterogeneity in distribution of malignant clones and the importance of correlating clonality with the patient's clinical presentation.
