Resistance to mogamulizumab is associated with loss of CCR4 in cutaneous T-cell lymphoma

Abstract

Mogamulizumab is a humanized anti-CC chemokine receptor 4 (CCR4) antibody approved for the treatment of mycosis fungoides and Sézary syndrome. Despite almost universal expression of CCR4 in these diseases, most patients eventually develop resistance to mogamulizumab. We tested whether resistance to mogamulizumab is associated with loss of CCR4 expression. We identified 17 patients with mycosis fungoides or Sézary syndrome who either were intrinsically resistant or acquired resistance to mogamulizumab. Low expression of CCR4 by immunohistochemistry or flow cytometry was found in 65% of patients. Novel emergent CCR4 mutations targeting the N-terminal and transmembrane domains were found in 3 patients after disease progression. Emerging CCR4 copy number loss was detected in 2 patients with CCR4 mutations. Acquisition of CCR4 genomic alterations corresponded with loss of CCR4 antigen expression. We also report on outcomes of 3 cutaneous T-cell lymphoma (CTCL) patients with gain-of-function CCR4 mutations treated with mogamulizumab. Our study indicates that resistance to mogamulizumab in CTCL frequently involves loss of CCR4 expression and emergence of CCR4 genomic alterations. This finding has implications for management and monitoring of CTCL patients on mogamulizumab and development of future CCR4-directed therapies.

Graphical abstract

Figure 1.

CCR4 expression decreases in a subset of patients after mogamulizumab treatment. (A) Total duration of treatment with mogamulizumab and best treatment responses. (B) CCR4 IHC expression pre- and posttreatment with mogamulizumab. Bars indicate mean H score. Lines connect paired samples from the same patient. (C-D) MFI of CCR4 by flow cytometry before and after treatment using 2 CCR4 antibodies: 1G1 (C) and KM2160 (D). *P < .05 by Mann-Whitney U test. H score, percentage of the CCR4⁺ cells among all cells in the infiltrate x intensity of expression 0-3+.

Figure 2.

Mutations in CCR4 arising after mogamulizumab treatment result in decreased CCR4 expression and reduced antibody dependent cellular cytotoxicity. (A) Diagram of resistance-associated CCR4 mutations (red circles) in 3 mogamulizumab-treated patients in relation to the mogamulizumab-binding epitope, transmembrane domains, and previously described GoF mutations (blue circles). (B) Jurkat cells were transfected with either CCR4wt, CCR4M116R, or CCR4L21V. MFI of CCR4 by flow cytometry is shown using 2 CCR4 antibodies: 1G1 (left) and KM2160 (right). (C) Normalized copy ratio of reads binned across chromosome 3. Yellow line indicates segmented copy number alterations. (D) Antibody-dependent cellular cytotoxicity assay. Jurkat transfectants were cocultured with a Jurkat reporter cell line expressing FcγRIIIa and firefly luciferase under an NFAT response element. Cells were incubated overnight with or without the human anti-CCR4 antibody KM0761 prior to detection of luciferase activity. Erros bars indicate standard deviation. (E) IHC staining of CCR4 in skin biopsies of 3 patients before (top) and after (both) progression on mogamulizumab. Each row of images represents paired biopsies from the same patient. (F) Response to mogamulizumab in the skin (black) and blood (red) in a patient with Sézary syndrome and a C329X GoF mutation of CCR4.