Skin Toxicity Treatment in Metastatic Colorectal Cancer (mCRC) Patients Receiving Panitumumab + Irinotecan-based Therapy (STEPP)

Skin toxicities were assessed by the study clinician and graded according to the modified Common Toxicity Criteria for Adverse Events (CTCAE) v.3.0 Dermatology Toxicity Grading criteria, on a scale from Grade 1 (mild) to 4 (life-threatening). The specific skin toxicities of interest were pruritus, acneiform dermatitis, skin desquamation (also described as skin exfoliation), exfoliative dermatitis, paronychia, nail disorder, skin fissures, skin laceration, pruritic rash, pustular rash, skin infection, skin ulceration, and local infection.

The percentage of participants who developed at least 1 incidence of ≥ grade 2 skin toxicities of any type during the 6-week skin treatment period. Analysis of this endpoint was based on adverse event data associated with the "Skin and Subcutaneous Tissue Disorders" system organ class. Adverse events were graded according to the National Cancer Institute (NCI) CTCAE version 3.0.

The time to the first occurrence of specific grade 2 or higher skin toxicities of interest was defined as the time from the first dose of panitumumab to the date of first occurrence of specific ≥ grade 2 skin toxicities of interest. Participants who did not experience specific skin-related toxicities were censored at their last skin toxicity assessment during the skin toxicity assessment period. Skin toxicities were assessed by the study clinician and graded according to the modified CTCAE v.3.0 Dermatology Toxicity Grading criteria, on a scale from Grade 1 (mild) to 4 (life-threatening). The specific skin toxicities of interest were pruritus, acneiform dermatitis, skin desquamation (also described as skin exfoliation), exfoliative dermatitis, paronychia, nail disorder, skin fissures, skin laceration, pruritic rash, pustular rash, skin infection, skin ulceration, and local infection.

The percentage of participants with a most severe grade of 2, 3 or 4 specific skin toxicity of interest reported during the 6-week skin treatment period. Skin toxicities were assessed by the study clinician and graded according to the modified CTCAE v.3.0 Dermatology Toxicity Grading criteria, on a scale from Grade 1 (mild) to 4 (life-threatening). The specific skin toxicities of interest were pruritus, acneiform dermatitis, skin desquamation (also described as skin exfoliation), exfoliative dermatitis, paronychia, nail disorder, skin fissures, skin laceration, pruritic rash, pustular rash, skin infection, skin ulceration, and local infection.

Time to the first most severe grade ≥ 2 of all the specific skin-related toxicities of interest was defined as the time from the first dose of panitumumab to the date of the first occurrence of the most severe specific ≥ grade 2 skin toxicity of interest during the 6-week skin treatment period. Participants who did not experience any specific skin-related toxicity of grade ≥ 2 were censored at their last skin toxicity assessment during the 6-week skin toxicity assessment period. Skin toxicities were assessed by the study clinician and graded according to the modified CTCAE v.3.0 Dermatology Toxicity Grading criteria, on a scale from Grade 1 (mild) to 4 (life-threatening). The specific skin toxicities of interest were pruritus, acneiform dermatitis, skin desquamation (also described as skin exfoliation), exfoliative dermatitis, paronychia, nail disorder, skin fissures, skin laceration, pruritic rash, pustular rash, skin infection, skin ulceration, and local infection.

Tumor response was assessed by computed tomography (CT) scan or magnetic resonance imaging (MRI) of the abdomen, pelvis, and all other sites of disease. Disease assessments were performed by central review according to the modified response evaluation criteria in solid tumors (RECIST). Response rate is defined as the percentage of participants with a complete response (CR) or partial response (PR) at the Week 9/10 assessment visit and a corresponding CR or PR confirmed at the Week 13/14 assessment visit for the Q2W/Q3W regimens. CR: Disappearance of all target and non-target lesions and no new lesions. PR: Either the disappearance of all target lesions with persistence of one or more non-target lesion(s) not qualifying for either CR or progressive disease (PD; ≥ 25% increase in lesion size) and no new lesions, or, at least a 30% decrease in the size of target lesions with no progression of existing non-target lesions, and no new lesions.

Best overall response rate is defined as the percentage of participants with a complete response (CR) or partial response (PR) while on study. Tumor response was assessed by CT scan or MRI of the abdomen, pelvis, and all other sites of disease. Disease assessments were performed by central review according to the modified RECIST criteria. CR: Disappearance of all target and non-target lesions and no new lesions. PR: Either the disappearance of all target lesions with persistence of one or more non-target lesion(s) not qualifying for either CR or PD (≥ 25% increase in lesion size) and no new lesions, or, at least a 30% decrease in the size of target lesions with no progression of existing non-target lesions, and no new lesions.

Tumor response was assessed by CT scan or MRI of the abdomen, pelvis, and all other sites of disease. Disease assessments were performed by central review according to the modified response evaluation criteria in solid tumors (RECIST). Disease control rate is defined as the percentage of participants with a CR, PR or stable disease (SD) at the Week 9/10 assessment visit and a corresponding response (CR or PR) confirmed at the Week 13/14 assessment visit for the Q2W/Q3W regimens. SD: Neither sufficient shrinkage or increase in target lesions to qualify for PR or PD, with no progression of non-target lesions and no new lesions.

Time-to-treatment failure is defined as the time from the date of randomization to the first date of any of the following events: discontinuation of study therapy due to any reason (except for complete response and curative surgery), progression of disease, or death due to any cause. Participants who did not discontinue, who were still alive, and who did not have disease progression were censored at the date of last contact. Time to treatment failure was analyzed using the Kaplan-Meier method.

Time from the date of randomization to the date of observed disease progression or death due to disease progression. Participants who did not have documented disease progression were censored at the date of last tumor assessment; participants who died for reasons other than disease progression while on study were censored at the date of death. PD: At least a 20% increase in the size of target lesions, recorded since the treatment started, or at least a 25% increase in size of non-target lesions and the lesion(s) measure > 10 mm in one dimension, or the appearance of one or more new lesions. Time to progression was analyzed using the Kaplan-Meier method. This analysis excludes any data collected during follow-up for participants who began third-line treatment.

Overall Survival is defined as the time from the date of randomization to the date of death. Participants who did not die while on study or who were lost-to-follow-up were censored at their last contact date. Overall survival was analyzed using all data regardless of whether it was collected during second- or third-line treatment.

Defined as the time from the date of randomization to the first date of observed disease progression or death due to any cause (whichever comes first). Participants who were alive and had not progressed while on study were censored at the date of last progression-free tumor assessment.

Skin-related quality of life was assessed using the DLQI. The DLQI questionnaire asks participants to evaluate the degree that their skin condition has affected their quality of life in the last week. Participants answer 10 questions on a scale from 0 (not at all) to 3 (very much); The DLQI score is calculated by summing the scores for all questions, resulting in a maximum of 30 and a minimum of 0; higher scores indicate a more impaired quality of life.