HD-IL-2 meta-analysis

Background

Pooled analysis of 270 patients with metastatic melanoma treated with high-dose bolus interleukin-2 (HDIL-2, aldesleukin) across 8 clinical trials conducted 1985-1993.

Interventions and follow up

Regimen: high-dose IL-2 600,000-720,000 IU/kg IV over 15min q8h x14 doses over 5d, rest 6-9d, then a second 14-dose cycle; repeated q6-12wk
Design: pooled retrospective analysis of 8 trials
Primary endpoint: objective response rate and durability of response
Median follow-up: 62mo (~5.1yr)

Results

ORR: 16% overall
CR: 6%; PR: 10%
Median duration of response: not reached for CR; 5.9mo for PR
mPFS: 13.1mo
mOS: 11.4mo

Adverse events

Cardiovascular/capillary leak: hypotension 64%, tachycardia 17%
Organ toxicities: pulmonary 31% (grade 3 in 9%), renal 49%, GI 24%, infections 15%
Treatment-related death: 2.2% (n=6); toxicity resembles septic shock and requires ICU-level care with frequent vasopressor support

Conclusions

High-dose IL-2 produced durable complete responses in a minority of metastatic melanoma patients (median OS 11.4mo), establishing the first immunotherapy capable of inducing long-term remissions and presaging the modern checkpoint-inhibitor era.

Key Limitations

Pooled, non-randomized retrospective data; low overall response rate with substantial life-threatening toxicity restricting use to fit patients at specialized centers; superseded by checkpoint inhibitors with better efficacy and tolerability.

Clinical Context

Supported FDA approval of high-dose IL-2 for metastatic melanoma (1998), the standard for durable responses prior to checkpoint inhibitors. Now rarely used given the superiority and tolerability of anti-PD-1-based therapy. ESMO favors checkpoint inhibition first-line.

References