Therapeutic Role and Toxicity Profile of High-Dose Interleukin-2 in Metastatic Melanoma and Renal Cell Carcinoma: A Narrative Review
Abstract
A narrative review examining the biological basis, clinical efficacy, toxicity profile and contemporary clinical relevance of high-dose interleukin-2 in metastatic melanoma and renal cell carcinoma.
High-dose interleukin-2 (HD IL-2) is one of the earliest clinically proven immunotherapy approaches for solid tumours. In a selected subset of patients with stage III or IV metastatic melanoma and renal cell carcinoma, HD IL-2 has demonstrated the ability to produce meaningful and prolonged therapeutic benefit, including durable remissions without further systemic treatment.
Durable therapeutic benefit from HD IL-2 depends on a strong immune response involving substantial proliferation and functional activation of immune effector cells, particularly cytotoxic T lymphocytes and natural killer cells. These mechanisms support immune-mediated tumour regression in responsive patients.
Evidence from early National Cancer Institute trials, multi-institutional studies and registry-based experience has demonstrated objective response rates of approximately 15–20% in metastatic melanoma and 20–25% in metastatic renal cell carcinoma. A small but clinically important minority of patients achieve durable complete remissions.
The clinical use of HD IL-2 is restricted by a narrow therapeutic window and substantial toxicity. Major adverse effects include capillary leak syndrome, cardiovascular instability, renal impairment and neuropsychiatric toxicity. Administration therefore requires inpatient care, intensive monitoring and experienced specialist centres.
Although contemporary oncology is dominated by immune checkpoint inhibitors and increasingly by engineered IL-2 variants, HD IL-2 retains historical and clinical importance because of its capacity to produce durable, treatment-free remissions in carefully selected patients.
Mechanistic, clinical and historical evidence synthesis.
Approximate objective response rate reported in metastatic melanoma.
Approximate objective response rate reported in metastatic renal cell carcinoma.
Literature reviewed through December 2025.
T-Cell & NK-Cell Activation
IL-2 promotes proliferation and activation of cytotoxic CD8+ T lymphocytes and natural killer cells, supporting both adaptive and innate antitumour immune activity.
Early Cancer Immunotherapy
High-dose IL-2 played a foundational role in demonstrating that immune-system modulation could produce tumour regression in metastatic solid malignancies and helped establish modern cancer immunotherapy.
15–20% Objective Response
The review reports objective response rates of approximately 15–20% in metastatic melanoma, with a small subset achieving prolonged complete remission.
20–25% Objective Response
In metastatic renal cell carcinoma, historical and registry-based experience suggests objective response rates of approximately 20–25%, again with durable complete responses in a minority of patients.
Treatment-Free Complete Remission
A distinctive feature of HD IL-2 is the possibility of long-term complete remission that persists for years after therapy has ended and may require no subsequent systemic treatment.
Capillary Leak Syndrome
Capillary leak syndrome is a defining treatment-related toxicity and contributes to hypotension, fluid shifts and haemodynamic instability during high-dose IL-2 therapy.
Cardiovascular, Renal & Neurological Effects
Other important toxicities described in the review include cardiovascular instability, reversible renal impairment and neuropsychiatric effects, requiring close inpatient observation.
Specialist Inpatient Therapy
Because of the intense physiological effects of HD IL-2, treatment is restricted to carefully selected patients with adequate cardiopulmonary and metabolic reserve and is administered in specialised centres.
Checkpoint Inhibitor Era
The role of conventional HD IL-2 has narrowed as immune checkpoint inhibitors have become dominant treatments for melanoma and renal cell carcinoma, offering broader clinical applicability and generally improved tolerability.
Engineered IL-2 Variants
The review discusses engineered IL-2 approaches designed to preserve or enhance antitumour immune activation while reducing regulatory T-cell stimulation and treatment-related toxicity.
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Narrative Review
This publication is a narrative review integrating mechanistic, historical and clinical evidence concerning high-dose interleukin-2 therapy in metastatic melanoma and renal cell carcinoma.
PubMed, Embase & Cochrane Library
The methodology describes searches of PubMed, Embase and the Cochrane Library to identify relevant oncology and immunotherapy literature.
1990 – December 2025
The review considered literature relating to the development, clinical use, efficacy, response durability and toxicity of high-dose IL-2 from 1990 through December 2025.
Clinical & Translational Literature
The review considered phase I–III clinical trials, large prospective and retrospective cohorts, national and international registries, and landmark translational studies relevant to high-dose IL-2.
Small & Non-Peer-Reviewed Reports
Case reports, small single-institution series and non-peer-reviewed sources were generally excluded unless they offered important historical or novel insight into IL-2 therapy.
Narrative Selection Bias
The author explicitly acknowledges that, unlike a systematic review, the narrative approach is susceptible to selection bias. Its advantage is the ability to integrate mechanistic, historical and clinical perspectives.
High-Dose Intravenous IL-2
The review describes contemporary high-dose IL-2 administration as intermittent intravenous bolus treatment, typically in highly specialised inpatient environments with intensive physiological monitoring.
Carefully Selected Candidates
Because of potentially life-threatening toxicity, eligible patients require adequate cardiopulmonary and metabolic reserve and must be managed by teams experienced in high-dose cytokine therapy.
Durable Complete Responses
Although overall response rates are modest, HD IL-2 remains notable for the possibility of durable complete responses and prolonged treatment-free survival in a small subset of appropriately selected patients.
Checkpoint Inhibitors & Engineered IL-2
The article places conventional high-dose IL-2 within modern treatment pathways increasingly dominated by immune checkpoint blockade and emerging engineered IL-2 variants designed to improve therapeutic selectivity and tolerability.
AI-Assisted Writing & Editing
The author declares the use of AI-assisted tools in the writing and editing of the manuscript. The author retains full responsibility for the scientific content, literature assessment, interpretation and editorial input. AI systems were not used to generate original scientific conclusions, interpret clinical data or analyse scientific data.
Sole Author
Dr. Ishaan Bakshi conceived, wrote, revised and approved the final manuscript.
Conflict of Interest & Funding
Conflict of Interest:
No conflict of interest.
Funding:
No funding received by the author.
Editorial Timeline
CC BY 4.0
This article is published by The Operating Room Global
Journal under the Creative Commons Attribution 4.0
International licence.
DOI: 10.64573/torgj2512004
Volume 2 · Issue 1 · 2026
The Operating Room Global Journal (TORGJ).
ISSN 3105-3262.
Article DOI: 10.64573/torgj2512004.
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