Lack of Durable Remission with Conventional-Dose Total Skin Electron Therapy for the Management of Sezary Syndrome and Multiply Relapsed Mycosis Fungoides

Advances in the pharmacological management of cutaneous T-cell lymphoma

INTRODUCTION

Current treatment guidelines for cutaneous T cell lymphoma (CTCL) advocate a stage-driven approach, considering clinical presentation, symptom burden, and patient comorbidities. Therapy selection hinges on factors like disease subtype, severity, and treatment availability. The primary goal is to enhance the quality of life by mitigating symptoms, as achieving lasting complete remission is infrequent.

AREAS COVERED

Over the past decade (2013-2023), the therapeutic landscape of CTCL has experienced substantial transformation with the introduction of innovative therapies. This review explores the main pivotal developments in traditional treatment schedules and recently introduced drugs, aiming to offer clinicians and researchers a thorough perspective on the decade's progress in the field.

EXPERT OPINION

Despite the progress made in CTCL therapeutics, ranging from topical chemotherapeutics to immunomodulatory agents, several unmet needs persist. Firstly, there is a pressing need for the incorporation of readily available predictors for treatment response, encompassing clinical, pathological, and molecular features. Secondly, a more profound comprehension of the tumor microenvironment is imperative to optimize the landscape of targetable molecules. Lastly, the undertaking of studies on combination regimens should be encouraged as it enhances therapy efficacies by synergistically combining agents with diverse modes of action.

International study of treatment efficacy in SS shows superiority of combination therapy and heterogeneity of treatment strategies

Despite increasing availability of therapies, patients with Sezary syndrome (SS) commonly endure multi-line treatment journeys, mostly with partial responses of short duration. Measuring clinical benefit is challenging; time-to-next-treatment (TTNT) provides a robust, objective measurement of efficacy. This international observational study examines patterns of clinical care and therapeutic benefit as measured by TTNT. TTNT was calculated for monotherapies and combination therapies, with consideration to treatment line. 178 patients with SS (73% de novo, 27% secondary) were included, receiving 721 lines of systemic therapy, with median follow-up of 56.9 months. Across all lines, 58 different therapeutic regimens were prescribed (54 were systemic therapies) and classified into 17 treatment groups. The most common first-line treatments were extracorporeal photopheresis (ECP)-containing combination therapy (20%) and retinoid monotherapy (19%). Median TTNT for all first-line therapies was short (5.4 months). First-line, combination therapies had longer median TTNT than monotherapies, 10.0 vs 5.0 months (P = .004), respectively. Later delivery of combination therapies was associated with shorter clinical benefit, with median TTNT reduced to 6.2 and 2.2 months for mid-line (2nd-4th line) and late-line (≥5th line), respectively (P < .001). First-line ECP-containing treatments were associated with longer median TTNT than non-ECP-containing treatments, 9.0 vs 4.9 months (P = .007). For both ECP-monotherapy and ECP-containing combination therapy, significant reductions in TTNT were seen in later lines. These data suggest therapeutic benefit from first-line delivery of combination therapy for SS and favor early inclusion of ECP in the treatment algorithm for those who can access it.

Low-Dose Total Skin Electron Beam Therapy as Part of a Multimodality Regimen for Treatment of Sézary Syndrome: Clinical, Immunologic, and Molecular Analysis

Importance

Sézary syndrome (SS) is an advanced form of cutaneous T-cell lymphoma with few long-term remissions observed.

Objective

To profile 3 patients with SS who have experienced long-term remission following the addition of low-dose total skin electron beam therapy (TSEBT) to systemic regimens of extracorporeal photopheresis, bexarotene, and interferon-γ.

Design, Setting, and Participants

This is a retrospective case series with additional investigations of patient-donated samples to assess therapeutic response. The study was conducted at the University of Pennsylvania Cutaneous Lymphoma Clinic and follows 3 patients with stage IVA1 CD4+ SS who presented to the clinic between November 1, 2009, and November 1, 2017, and who had a history of SS that was refractory to multimodality systemic therapy prior to receiving low-dose TSEBT.

Interventions

Patients were treated in a multimodality fashion with combined extracorporeal photopheresis, bexarotene, interferon-γ, and low-dose TSEBT.

Main Outcomes and Measures

To characterize treatment responses in these patients, the extent of skin disease was measured with the modified severity weighted assessment tool. Blood disease was measured with flow cytometric assessments of Sézary cell count, CD4:CD8 ratio, and high throughput sequencing of the T-cell receptors. To assess for restoration of immune function, we measured markers of immune exhaustion, including PD-1 (programmed cell death 1), TIGIT (T-cell immunoreceptor with immunoglobulin and ITIM domains), CTLA4 (cytotoxic T-lymphocyte-associated protein 4), TOX (thymocyte selection-associated high mobility group box protein), and Foxp3 (forkhead box P3) on circulating CD4 and CD8 T cells, along with production capacity of interferon-γ by lymphocytes following activation stimuli.

Results

Following administration of low-dose TSEBT and maintenance of the other therapies, remissions ranged from 24 to 30 months, with complete responses in 2 patients ongoing. Markers of immune exhaustion including PD-1, TIGIT, CTLA4, TOX, and Foxp3 were significantly reduced from baseline following TSEBT, along with enhanced production capacity of interferon-γ by lymphocytes following activation stimuli. High throughput sequencing demonstrated near-complete eradication of the circulating clone among 2 of 3 patients with stable levels in 1.

Conclusions and Relevance

We describe 3 patients who achieved long-term clinical and molecular remissions following low-dose TSEBT as part of a multimodality regimen for treatment of SS. As long-term remissions in SS are uncommon, this approach demonstrates promise, and clinical trials should be considered.

Mycosis fungoides and Sézary syndrome: Australian clinical practice statement

Primary cutaneous lymphomas represent a heterogeneous group of T- and B-cell lymphomas with distinct clinical presentations, histopathologic features, treatment approaches and outcomes. The cutaneous T-cell lymphomas, which include mycosis fungoides and Sézary syndrome, account for the majority of the cutaneous lymphomas. This Clinical Practice Statement is reflective of the current clinical practice in Australia. An expanded form of the Clinical Practice Statement (and updates), along with helpful patient resources and access to support groups, can be found at the following (http://www.australasianlymphomaalliance.org.au).

Time to Next Treatment as a Meaningful Endpoint for Trials of Primary Cutaneous Lymphoma

Time to next treatment (TTNT) is an emerging endpoint in clinical studies of primary cutaneous T-cell lymphomas (CTCL), with utility as a surrogate marker for the “duration of clinical benefit”. TTNT provides a highly clinically meaningful endpoint that uniquely reflects not only the duration of treatment efficacy on disease and symptom control, but also incorporates the patient experience by accounting for patient compliance and tolerance to the studied therapy(s). Given the distinct challenges of pin-pointing the exact date of progression in patients with multi-compartmental CTCL, TTNT overcomes many of the shortcomings of conventional, disease-focused, clinical endpoints in primary CTCL research. Although widely accepted in clinical research for numerous other incurable malignancies, TTNT currently lacks a standardised definition. In this paper, we describe the value of TTNT as a clinical endpoint, review the applications of TTNT in primary CTCL research, and propose a standardised definition of TTNT to be applied in future clinical research of primary CTCL therapies.