NKTR-102 Versus Irinotecan in Patients With Second-Line, Irinotecan-Naïve, KRAS Mutant, Colorectal Cancer

PFS was defined as the time from the date of randomisation to the date of disease progression (assessed by central radiological review according to Response Evaluation Criteria in Solid Tumors [RECIST] 1.1) or death due to any cause, whichever comes first. PFS was determined using the intention-to-treat (ITT) population which included all randomized patients who underwent baseline evaluation, with treatment assigned according to randomized arm. For patients whose disease did not progress or who did not die, the PFS time was censored at the time of the last tumor assessment that demonstrated lack of disease progression. For patients who received new anti-cancer therapy, the PFS time was censored at the time of last tumor assessment prior to the new anti-cancer therapy starts.

Duration of OS was defined as the time from the date of randomization to the date of death due to any cause. Patients were followed until their date of death, loss to follow-up, withdrawal of consent for further follow-up for survival, or final database closure. Patients who were lost-to-follow-up or were not known to have died were censored at last date they were shown to be alive. Patients who did not have any follow-up since the date of randomization were censored at the date of randomization.

ORR was defined as the proportion of patients with a complete response (CR) or a partial response (PR) per RECIST 1.1 based upon the best response as assessed by central radiological review; confirmation of response was not required. The analyses were performed for patients in the ITT population who had measurable disease as determined by the central imaging facility at baseline.

Progressive Disease (PD) is defined as at least a 20% increase in the sum of the diameters of target lesions, taking as reference the smallest sum on study (this includes the baseline sum if that was the smallest on study); in addition to a relative increase of 20%, the sum must have also demonstrated an absolute increase of at least 5 mm. CR is defined as disappearance of all target lesions; any pathological lymph nodes (whether target or non-target) must have had a reduction in short axis to < 10 mm. PR is defined as at least a 30% decrease in the sum of diameters of target lesions, taking as reference the baseline sum diameters

An adverse event (AE) was any untoward medical occurrence in a patient administered a pharmaceutical product which did not necessarily have a causal relationship with the treatment. An AE could have been any unfavorable and unintended sign, symptom, or disease temporally associated with the use of a medicinal product, whether or not considered related to the medicinal product. Pre-existing events, which increased in frequency or severity or changed in nature during or as a consequence of use of the study medication were also considered as AEs. All AEs were assessed for severity using the National Cancer Institute - Common Terminology Criteria for Adverse Events (NCI-CTCAE), Version 3.0. If a particular AE was not listed in the NCI CTCAE Version 3.0, the following criteria were used: Grade 3 = severe; Grade 4 = life threatening or disabling; Grade 5 = death.

Blood samples for PK analysis were collected from 4 patients only, 3 from the irinotecan treatment arm and 1 from the NKTR-102 treatment arm. NKTR-102, irinotecan, SN38, SN38-G, 7-ethyl-10-[4-N-(5-aminopentanoic acid)-1-piperidino]carbonyloxycamptothecin, and 7-ethyl-10-(4-amino-1-piperidino) carbonyloxycamptothecin concentration levels were determined. However, due to the limited number of patients with PK samples, no further PK analysis was conducted.