Cycle 1
Name	NC/NA, %	Grade 1, %	Grade 2, %	Grade 3, %	Grade 4, %	Grade 5, %	All grades, %
Rash maculo‐papular	11	11	67	11	0	0	89
Fatigue (asthenia, lethargy, malaise)	56	22	22	0	0	0	44
Diarrhea	56	22	11	11	0	0	44
Vomiting	78	0	22	0	0	0	22
Anorexia	78	11	11	0	0	0	22
Alanine aminotransferase increased	89	0	0	11	0	0	11
Aspartate aminotransferase increased	78	11	11	0	0	0	22
Distension/bloating, abdominal	89	11	0	0	0	0	11
Hair loss/alopecia (scalp or body)	89	11	0	0	0	0	11
Dry skin	89	11	0	0	0	0	11
Headache	89	11	0	0	0	0	11
Confusion	89	11	0	0	0	0	11
Edema limbs	89	11	0	0	0	0	11
Edema face	89	11	0	0	0	0	11
Creatinine increased	89	11	0	0	0	0	11
Dyspnea (shortness of breath)	89	11	0	0	0	0	11
Pruritus/itching	89	11	0	0	0	0	11
Irritability	89	0	11	0	0	0	11

Adverse Events Legend

Treatment‐related adverse events occurred in all patients (100%). Most were low‐grade, with only one patient (11%) experiencing grade 3 adverse events. No grade 4 or 5 events occurred. Consistent with previously reported data on trametinib [5], the most common toxicity was rash (89%). Six of nine patients required dose reduction secondary to rash (four patients’ dose reduced to 1.5 mg, two patients’ dose reduced to 1.0 mg). Other common toxicities included fatigue (44%), diarrhea (44%), aspartate aminotransferase/alanine aminotransferase (AST/ALT) elevations (22%), and anorexia (22%). One patient discontinued treatment because of toxicity; this patient experienced grade 3 rash as well as diarrhea, elevated AST/ALT, and fatigue (Table 2).

Abbreviation: NC/NA, no change from baseline/no adverse event.