This is a prospective, single-arm, phase II clinical trial that will enroll metastatic colorectal cancer patients with Cetuximab-Related Skin Toxicity, who will receive crisaborole ointment twice daily.

The efficacy of cetuximab has been demonstrated in treating metastatic colorectal cancer (mCRC). Skin toxicities, especially acneiform eruption, are the major side effects associated with cetuximab, which affect patients' quality of life and can lead to treatment discontinuation and cetuximab dose reduction.

This prospective, single-arm, phase II clinical trial aims to explore the efficacy and safety of crisaborole ointment in Cetuximab-Related Skin Toxicity. A total of 33 mCRC patients with acneiform eruption will be enrolled. All of the participants will receive crisaborole ointment twice daily. The total follow-up time is 12 weeks.

Inclusion Criteria:

1. Diagnosed mCRC and undergoing Cetuximab treatment;
2. ≥2 grade EGFR inhibitor-related acneiform eruption, evaluated by National Cancer Institute (NCI) Common Terminology Criteria Adverse Events (CTCAE）5.0;
3. Age 18 years and older；
4. ECOG performance status 0-2.；
5. Bone marrow ,brain, heart, kidney and other organ function well;；
6. Expected survival time more than 3 months;

Exclusion Criteria:

1. The presence of any active skin disease；
2. Undergoing any current hormone therapy for any other disease;
3. Prior allergic reaction or severe intolerance to crisaborole ointment