Clinical Research and Genomic Analysis on Relapsed or Refractory Angioimmunoblastic T Cell Lymphoma with Chidamide Monotherapy

BACKGROUND: This study was to evaluate the efficacy and safety of chidamide monotherapy, which is a new histone deacetylase inhibitor (HDAci) of the benzamide class, in relapsed or refractory Angioimmunoblastic T cell lymphoma (AITL), to investigate its genomic expression signatures as well as the mechanisms of chidamide's anti-lymphoma effect and its resistance.

METHODS: Two cases with relapsed or refractory AITL were treated with chidamide. We performed a repeated biopsy on relapsed lymphomas and did whole genome next-generation sequencing (NGS) testing on drug -resistant tumor samples.

RESULTS: The first patient is a 54-year-old man presented with stage Ⅳ AITL. He underwent autologous stem cell transplantation in his first complete remission (CR) but relapsed 7 months later. In view of resistance to multiple lines of chemotherapy and poor performance status, chidamide was adaministered orally at a standard dose of 30mg twice a week. Pulmonary lesions regressed quickly and a second CR was achieved. Adverse events included grade 2 cytopenias, diarrhea, and reversible QT interval prolongation. The disease free survival was 6 months and AITL relapsed again 4 months ago. He responded to low-dose chidamide combined with lenalidomide and dexamethasone and remains well. Formalin-fixed, paraffin-embeded tumor tissues collected at first relapse were tackled for whole-genome sequencing. The other patient is a 62-year-old woman who had stage Ⅲ AITL. Disease progressed after two cycles of combined chemotherapy, thereafter a standard dose of chidamide monotherapy was initiated. With well tolerability, an unconfirmed CR was achieved and lasted for nearly 3 months. She is still alive but remains refractory to various salvage therapeutics, including chemotherapies, arsenic trioxide, thalidomide, and pralatrexate. A rebiopsy was perferomed and the histopathological findings confirmed the relapse of AITL, associated with Epstein-barr virus infection. Fresh tumor tissues were sent for whole-genome sequencing. In both cases, NGS testing identified mutations of RHOA gene, epigenetic regulators TET2, IDH1, and DNMT3A, as well as CD28.

CONCLUSIONS: Chidamide, a low nanomolar inhibitor of HDAC1, 2, 3, and 10, was approved in China for the management of relapsed and/or refractory peripheral T cell lymphoma. It's reported that patients with AITL tended to have higher response rates and more durable responses to chidamide treatment. Our report showed single-agent chidamide is a reasonable approach to treat the formidable disease but seemed difficult to achieve a sustained remission. Various genetic, epigenetic, and immune alterations involve in the pathogensis of AITL, which provide targets for chidamide therapy. High-throughput sequencing approach is very helpful to clarify the mechanisms.