COCOON Trial: Prophylactic Dermatologic Management in First‑Line EGFR‑Mutant NSCLC

An interim analysis of a randomized phase II dataset in advanced EGFR-mutant NSCLC reported lower early rates of moderate-to-severe dermatologic adverse events among patients assigned to a preemptive, bundled dermatologic protocol during initiation of first-line amivantamab plus lazertinib. In the COCOON trial interim analysis, the proportion of patients with any grade ≥2 dermatologic adverse event by 12 weeks was reported as 38.6% with enhanced prophylaxis versus 76.5% with standard reactive management, with p<0.0001. The interim report also outlined regimen components, dermatology-attributed treatment modifications, and tolerability findings over the same early time window.

The enhanced intervention was described as a structured package started with therapy, rather than symptom-triggered management. The prophylactic dermatologic bundle included oral doxycycline or minocycline at 100 mg twice daily for 12 weeks, along with daily use of a ceramide-based moisturizer planned for 12 months. Participants also used a 4% chlorhexidine wash applied daily to fingernails and toenails throughout therapy. After week 12, topical 1% clindamycin was introduced for daily scalp application beginning at week 13, and a smartphone-based tool was used to support completion of the prophylaxis steps. The comparator arm was described at a high level as standard reactive care during therapy initiation.

For additional dermatologic outcomes within 12 weeks, severe (grade 3) dermatologic AEs were reported less often with enhanced prophylaxis than with standard reactive management (4.3% vs 8.8%). The interim findings were also presented as consistent with fewer grade 3 dermatologic events in patients assigned to preemptive management compared with reactive management. The analysis further characterized the strategy as reducing the likelihood of more consequential early dermatologic toxicity, rather than shifting the timing of events within the same initial treatment window.

Dermatology-related treatment modification metrics were also reported during the same early period. Authors noted lower overall rates of dose interruptions (16% vs 34%), dose reductions (7% vs 19%), and discontinuations attributed to skin adverse events (1.4% vs 4.4%) for patients assigned to enhanced prophylaxis compared with reactive management. These percentages were presented as observed arm-level contrasts in the interim dataset, without extending interpretation beyond the 12-week analysis horizon. In this interim analysis, the prophylaxis approach was linked with fewer dermatology-attributed treatment modifications early in therapy.

Regarding tolerability of the prophylaxis measures, the antibiotic component was described as generally well tolerated, with infrequent mild photosensitivity or gastrointestinal upset, and no reported grade ≥3 events attributed to the antibiotics or Clostridioides difficile infections in the interim analysis. The topical and antiseptic elements were associated with infrequent mild local irritation in the reporting. Early antitumor activity assessed at 12 weeks was described as similar between arms, with an investigator-assessed objective response rate of about 80% and an interpretation that early activity did not appear reduced in this interim dataset.