Abstract 468P
Background
It is widely accepted that mCRC is a heterogeneous disease and that not every mCRC patient will benefit the most from the same treatment. Therefore, we conducted a study wherein FOLFOX plus panitumumab versus FOLFOX plus bevacizumab in patients with RAS WT unresectable mCRC was compared.
Methods
In this phase II study, 40 patients with mCRC were enrolled from 6 centres and were assigned 1:1 to the panitumumab or bevacizumab arm. The primary endpoint was progression free survival (PFS). Secondary endpoints included overall survival (OS), objective response rate (ORR), resection rate (RR) and safety profile.
Results
Cox proportional hazard analysis showed no significant difference in PFS (Hazard Ratio (HR) 0.789; 95% Confidence Interval (CI) 0.24-2.63; p=.700) with a median PFS of 13.58 months in the panitumumab arm and 9.33 months in the bevacizumab arm. Also, for OS no significant difference could be demonstrated (HR 0.673; 95% CI 0.28-1.60; p=.371). The RR and ORR were numerically higher in the panitumumab arm (3/20 and 16/19) than the bevacizumab arm (1/20 and 11/20). Data on adverse events and toxicity can be found in the accompanying table. Data of extended molecular testing and tumour location will be presented at the congress. Table: 468P
| Panitumumab (n = 20) | Bevacizumab (n = 20) | P value | |
| Sex Male/Female | 14/6 | 14/6 | |
| Age Median Range | 68 47-81 | 67 47-86 | |
| Median PFS | 13.58 months (95% CI 5.91-21.25) | 9.33 months (95% CI 0.00-20.34) | 0.700 |
| Median OS | 29.49 months (95% CI 19.60-39.37) | 31.16 months (95% CI 14.71-47.61) | 0.371 |
| Adverse events (AE) grade 3-4 | 15/20 (75%) | 6/20 (30%) | |
| Severe Adverse Events | 8/20 (40%) | 4/20 (20%) | |
| Grade 3-4 skin toxicity | 5/20 (25%) | 0/20 (0%) | |
| Grade 2 infusion reaction | 2/20 (10%) | 0/20 (0%) | |
| Treatment discontinuation because of AE or unacceptable toxicity | 4/20 (20%) | 1/20 (5%) | |
| Objective response rate | 16/19 (84%) | 11/20 (55%) | |
| Resection rate | 3/20 (15%) | 1/20 (5%) | |
| Early tumor shrinkage | 15/17 (88%) | 9/18 (50%) |
Conclusions
This trial shows no significant difference in PFS or OS (as can be expected based on the limited sample size) and the expected toxicity profiles were observed for each treatment group. The panitumumab arm showed a trend to a higher PFS, ORR and RR, which suggests important efficacy of this therapy. However, the results of this study must be interpreted with caution since this is a small study population. We conclude that the optimal therapy remains to be determined and that the development of predictive biomarkers in the future, might aid in the selection of the optimal therapy for mCRC patients.
Clinical trial identification
Editorial acknowledgement
Legal entity responsible for the study
Principal Investigators: Prof. Dr. Marc Peeters and Prof. Dr. Christian Rolfo.
Funding
Amgen.
Disclosure
C.D. Rolfo: Speaker Bureau/Expert testimony: Novartis; Speaker Bureau/Expert testimony: MSD; Advisory/Consultancy: Astra Zeneca; Advisory/Consultancy, Research grant/Funding (institution): Guardant Health; Research grant/Funding (institution): OncoDNA; Advisory/Consultancy: Mylan; Research grant/Funding (institution): Biocept. K. Op de Beeck: Advisory/Consultancy: Amgen. M. Peeters: Advisory/Consultancy, Speaker Bureau/Expert testimony, Research grant/Funding (institution): Amgen; Advisory/Consultancy, Speaker Bureau/Expert testimony, Research grant/Funding (institution): Bayer; Advisory/Consultancy: IQVIA; Advisory/Consultancy, Research grant/Funding (institution): Ipsen; Advisory/Consultancy: Remedus; Advisory/Consultancy, Speaker Bureau/Expert testimony: Sanofi; Advisory/Consultancy, Speaker Bureau/Expert testimony: Servier; Advisory/Consultancy, Speaker Bureau/Expert testimony: Sirtex; Advisory/Consultancy: Terumo; Speaker Bureau/Expert testimony: Celgene; Speaker Bureau/Expert testimony: MerckSerono; Speaker Bureau/Expert testimony, Research grant/Funding (institution): Roche; Research grant/Funding (institution): Novartis. All other authors have declared no conflicts of interest.