Study 07-PIR-02 is a Phase 2 study designed to evaluate the safety and efficacy of NKTR-102 (PEG-irinotecan) for the treatment of patients with colorectal cancer (CRC). The study is comprised of two sequential components - Phase 2a and Phase 2b. The Phase 2a portion is an open-label, dose-finding trial in multiple solid tumor types that are refractory to standard curative or palliative therapies. The primary endpoint of the Phase 2a is to establish the /recommended Phase 2 Dose (RPTD) of NKTR-102 by measuring the frequency of Dose Limiting Toxicity (DLT). The Phase 2b portion is an open-label, randomized, two-arm study in patients with second-line metastatic colorectal cancer and study participants will be randomized (1:1) to receive either NKTR-102 and cetuximab or irinotecan and cetuximab. The primary endpoint of the Phase 2b portion of the trial is progression-free survival. Secondary endpoints for both the Phase 2a and 2b portion include response rate, response duration, overall survival, standard pharmacokinetics, and incidence of toxicities, including diarrhea and neutropenia.