|The following article features coverage from the 2021 American Society of Clinical Oncology (ASCO) Annual Meeting. Click here to read more of Cancer Therapy Advisor‘s conference coverage.|
Panitumumab plus 5-fluorouracil/leucovorin (5FU/LV) should be regarded as the “preferred option” of maintenance therapy in patients with RAS wild-type metastatic colorectal cancer (mCRC), according to a presenter at the 2021 American Society of Clinical Oncology (ASCO) Annual Meeting.
Dominik Paul Modest, MD, of University Hospital of Munich in Germany, presented results from a phase 2 trial (ClinicalTrials.gov Identifier: NCT01991873) of panitumumab plus 5FU/LV at the meeting.
The PANAMA trial was designed to evaluate the efficacy and safety of panitumumab plus 5FU/LV as maintenance therapy in patients with RAS wild-type mCRC.
A total of 377 patients received induction with 6 cycles of 5FU/LV and oxaliplatin (FOLFOX) plus panitumumab. Patients who continued on study were randomly assigned to receive maintenance with 5FU/LV plus panitumumab (n = 125) or 5FU/LV alone (n = 123).
If their disease progressed, patients went on to receive reinduction with FOLFOX plus panitumumab, regardless of their prior treatment arm.
At baseline, the median age was 66 years in the panitumumab arm and 65 years in 5FU/LV-alone arm; 69.6% of the panitumumab arm and 63.4% of 5FU/LV-alone arm were men. Eastern Cooperative Oncology Group performance status was 0 in 56.8% of the panitumumab arm and 60.2% of the 5FU/LV-alone arm.
At the data cutoff, progression-free survival (PFS) was improved by adding panitumumab to 5FU/LV. The median PFS was 8.8 months in the panitumumab arm and 5.7 months in the 5FU/LV-alone arm (hazard ratio [HR], 0.72; 80% CI, 0.60-0.85; P =.014).
The overall survival (OS) data are not yet mature but numerically favored the panitumumab arm. The median OS was 28.7 months in the panitumumab arm and 25.7 months in the 5FU/LV-alone arm (HR, 0.84; 95% CI, 0.60-1.18; P =.32).
The objective response rate (ORR) during maintenance therapy was higher in the panitumumab arm than in the 5FU/LV-alone arm — 40.8% and 26.0%, respectively (odds ratio, 1.96; 95% CI, 1.14-3.36; P =.02).
Adverse events of special interest during maintenance were more frequent in the panitumumab arm. The most common grade 3-4 adverse events with panitumumab were skin rash (7.2% vs 0% in the 5FU/LV-alone arm), hypomagnesemia (6.4% vs 0%), paronychia (4.8% vs 0%), and infection (4% vs 0.8%).
Reinduction therapy was used more frequently in the 5FU/LV-alone arm (n = 75) than in the panitumumab arm (n = 45), and outcomes of reinduction favored the 5FU/LV-alone arm.
The ORR with reinduction was 8.9% in the panitumumab arm and 34.7% in the 5FU/LV-alone arm (HR, 0.18; 95% CI, 0.06-0.57; P =.002). The median PFS was 3.3 months and 5.8 months, respectively (HR, 2.62; 95% CI, 1.71-4.02; P <.001).
“Panitumumab is active as maintenance therapy in combination with 5FU/LV,” Dr Modest said in closing. “Therefore, the combination of 5FU/LV plus panitumumab should be regarded as the preferred option of maintenance therapy following FOLFOX-panitumumab in patients with RAS wild-type metastatic colorectal cancer.”
Disclosures: This research was supported by Amgen and Arbeitsgemeinschaft Internistische Onkologie (AIO). Some study authors declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of disclosures.
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Modest DP, Karthaus M, Frühauf S, et al. Maintenance therapy with 5-fluoruracil/leucovorin (5FU/LV) plus panitumumab (pmab) or 5FU/LV alone in RAS wildtype (WILD-TYPE) metastatic colorectal cancer (mCRC) – the PANAMA trial (AIO KRK 0212). J Clin Oncol. 2021;39:(suppl 15; abstr 3503). doi:10.1200/JCO.2021.39.15_suppl.3503