Aclarubicin Plus Cyclophosphamide, Vincristine, and Prednisone (CAOP) in Patients With Previously Treated Cutaneous T-cell Lymphoma

The estimated incidence of CTCL in China is 6.9 per million, accounting for 75% to 80% of primary cutaneous lymphomas. CTCL has diverse subtypes, stages, and clinical manifestations, with mycosis fungoides (MF) being the most common subtype. The etiology of CTCL remains unclear, but it may be related to DNA damage, epigenetic regulation, programmed cell death, and abnormalities in the T-cell receptor (TCR) signaling pathway.

The diagnosis and classification of CTCL primarily refer to the 5th edition of the World Health Organization (WHO) Classification of Hematopoietic and Lymphoid Neoplasms. A definitive diagnosis requires a comprehensive assessment of the patient's clinical presentation, histopathological findings, immunohistochemical staining, and TCR gene rearrangement testing. Sézary syndrome (SS) is no longer classified as CTCL in 5th edition of the WHO Classification. However, due to its close association with MF, current treatment recommendations still do not separate SS from MF. Early skin manifestations of CTCL include patchy or plaque-like lesions. Advanced stages may develop tumors or erythroderma. Extracutaneous involvement may also occur, often with regional lymph node involvement and the presence of atypical lymphocytes in the peripheral blood. Prognostic factors for CTCL include the presence of extracutaneous involvement, the body surface area of affected skin, the type of skin lesion, and the pathological type. Currently, disease staging and treatment efficacy assessment are primarily based on the 2022 ISCL/USCC/EORTC recommended criteria.

Commonly used systemic therapies for CTCL include interferon α, oral retinoids, histone deacetylase inhibitors, CD30 antibody-drug conjugates (velutuximab), and CCR4 monoclonal antibodies (moglizumab). The global Phase III MAVORIC study of moglizumab demonstrated a median progression-free survival (PFS) of 7.7 months and a median time to next treatment (TTNT) of 11 months in adult patients with relapsed/refractory SS or stage III-IV MF. The objective response rate (ORR) in hematology was 68%, and the ORR in skin reached 42%. However, due to cost and accessibility, clinical application in China remains limited. For patients who have failed these systemic therapies, existing combination chemotherapy regimens, while effective, are limited by patient tolerance, toxicity, and comorbidities, making continued use difficult.

Aclarubicin (Acla) is an anthracycline anticancer drug. In vitro, Acla has demonstrated potent cytotoxicity against various lymphoma and T-lymphocytic leukemia cell lines. Mechanistic studies of anthracyclines have revealed that doxorubicin, epirubicin, daunorubicin, and idarubicin all induce tumor cell apoptosis through two mechanisms: 1. DNA damage: through inhibition of topoisomerase II (Topo II), leading to DNA double-strand breaks (DSBs); and 2. Chromatin damage: through histone removal, causing chromatin alterations at specific genomic loci. However, these dual mechanisms also lead to dose-dependent, irreversible cardiotoxicity. Compared with classic anthracyclines (such as doxorubicin and daunorubicin), Acla does not cause DNA damage and accumulates significantly in lymphoid tissues (spleen, thymus, and lymph nodes), with poor distribution to other tissues. Consequently, its cardiotoxicity is significantly reduced. Even at high cumulative doses, it is less likely to cause cardiac dysfunction. Therefore, Acla may offer a safer option for elderly patients or those with concomitant heart disease. Previous studies have shown that the combination of Acla and cytarabine (such as the CAG regimen) has some efficacy and is well tolerated in relapsed/refractory and elderly patients with acute myeloid leukemia. In the 1980s and 1990s, studies explored the use of Acla in chemotherapy regimens for non-Hodgkin's lymphoma and Hodgkin's lymphoma, demonstrating some activity. Small studies have shown that Acla monotherapy can achieve a response rate of approximately 30% in patients with advanced non-hedging lymphoma, without compromising cardiac function. Japanese researchers have found that combination chemotherapy regimens containing Acla in T-cell lymphomas exhibit superior efficacy.

In this study, the investigators will replace doxorubicin in the traditional CHOP regimen with aclarubicin, a drug with proven efficacy and low cardiotoxicity, to create a novel aclarubicin, cyclophosphamide, vincristine, and prednisone (CAOP) regimen for patients with relapsed/refractory CTCL and SS who have received at least one prior systemic therapy. This combination chemotherapy regimen may improve efficacy while balancing tolerability and safety, providing a new treatment option for elderly patients with CTCL.