Phase IB/II Study of Second-Line Therapy with Panitumumab, Irinotecan, and Everolimus (PIE) in KRAS Wild-Type Metastatic Colorectal Cancer

Purpose: Inhibition of mTOR in addition to EGFR may overcome resistance to EGFR inhibitors in metastatic colorectal cancer (mCRC). This phase Ib/II study evaluated the safety and efficacy of the combination of irinotecan, panitumumab, and everolimus.Patients and Methods: Patients with KRAS exon 2 wild-type (WT) mCRC following failure of fluoropyrimidine-based therapy received i.v. irinotecan and panitumumab every 2 weeks, and everolimus orally throughout a 14-day cycle. The primary endpoint of the phase II study was response rate (RR). Secondary survival outcomes were calculated using the Kaplan-Meier method, and results were analyzed as intention to treat. A preplanned exploratory biomarker analysis was performed.Results: Forty-nine patients were enrolled. Dose level 1 (irinotecan 200 mg/m², panitumumab 6 mg/kg, and everolimus 5 mg alternate day) was declared the MTD with no dose-limiting toxicities in six patients. Forty patients were treated at dose level 1: median age, 60 years (37-76); 65% male; 45% and 52.5%, respectively, with Eastern Cooperative Oncology Group values of 0/1. Median dose intensity was 85%. Grade 3 toxicities were diarrhea (23%), mucositis (18%), rash (13%), fatigue (8%), dehydration (5%), neutropenia (20%), febrile neutropenia (8%), hypomagnesemia (20%), and hypokalemia (8%). Grade 4 toxicities were hypomagnesemia (5%) and neutropenia (3%). RR was 48%, and stable disease was 43%. Median progression-free survival (PFS) was 5.6 months, and median overall survival (OS) was 10.8 months. Twenty-five patients were RAS/RAF WT and had an RR of 60%, median PFS of 6.4 months, and OS of 11.8 months.Conclusions: The toxicity of the panitumumab, irinotecan, and everolimus regimen is as expected and manageable. The RR of 60% in all RAS/RAF WT supports further study of this combination. Clin Cancer Res; 24(16); 3838-44. ©2018 AACR.

Persistent oxaliplatin (OX) induced peripheral neuropathy in patients (pts) with colorectal cancer: A descriptive study

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Background: Available data suggest that the OX-induced neuropathy is usually reversible and a minority of pts will have persistent severe (grade 3) side effects (24.1% any grade and 0.7% grade 3 at 18 months follow up from MOSAIC trial). We have explored the frequency of persistent peripheral neuropathy in pts who received OX for colorectal cancer at 2 local centres in South Australia. Methods: Pts who completed treatment with OX for colorectal cancer at least 20 months prior to entering the study were eligible and were sent consent and questionnaire. Neuropathy questions were adapted from the FACT/GOG-Ntx (V.4) questionnaire. No pts received Calcium and Magnesium with OX. Statistical tests used to analyze the data were t-test and chi- square. Results: Of the 56 eligible pts, 27 consented to enrol in the study. Median age was 66 yrs. 19 were stage 3, 8 stage 4. Mean total OX dose was 712.1 mg/m2 (range: 170 - 1200 mg/m2); mean number of OX cycles was 8.2 (range 2 - 13), median time between last dose of OX and completing the questionnaire was 37 months (range 20 - 93). 7 pts (25.9%) had a history of diabetes mellitus and 7 had significant alcohol intake. No pts had neuropathic symptoms prior to treatment with OX. 25 pts (92.7%) experienced neuropathic symptoms during their treatment, 11 had grade 2, and 2 had grade 3 symptoms (limiting self care activities of daily living). At the time of completing the questionnaire, 17 pts (63%) were still symptomatic with 9 pts (33.3%) having grade 2 and 3 pts (11.1%) having grade 3 neuropathic symptoms. In the cohort of pts with persistent grade 2 symptoms, 3 pts had walking difficulty and 2 pts could not drive safely due to side effects. Persistent grade 2/3 symptoms were more common in pts who received total OX doses of 722 mg/m2 or more (p < 0.05). Conclusions: Our observation indicates that a majority of pts will have persistent neuropathy more than 20 months after completing treatment with OX and a significant proportion will still have grade 2/3 symptoms. Higher total OX dose might be one of the risk factors in this group. These results should be further prospectively evaluated in a larger population as these long term side effects may affect pts’ daily activities and safety.