Overall Survival in Patients with Metastatic CRC During 1st-Line Anti-EGFR Treatment Depending on the Presence or Absence of Hypomagnesemia

Study Methodology and Population

A total of 68 patients with metastatic primarily unresectable CRC were included in a retrospective study at a hospital in Ogaki, Japan. From January 2010 to December 2019, they were indicated for first-line therapy with the anti-EGFR antibodies cetuximab (n = 37; median age 64 years) or panitumumab (n = 31; median age 68 years). Based on medical records, the following parameters were evaluated: overall survival (OS), duration of treatment, therapeutic response, reason for treatment discontinuation, and side effects (hypomagnesemia).

Results

In the group of patients treated with cetuximab, a higher percentage had peritoneal metastases (p = 0.014).

Complete and partial remission was achieved without statistically significant difference by 60.0% of patients treated with cetuximab and 72.0% treated with panitumumab (p = 0.470). Significantly longer OS was observed in the group of patients treated with panitumumab (median 1007 days) compared to cetuximab (median 735 days; p = 0.047).

Hypomagnesemia as a side effect of therapy was significantly more frequent (p = 0.009) in patients treated with panitumumab (n = 15) than with cetuximab (n = 7). However, no significant impact of the presence or absence of hypomagnesemia on OS was observed, which averaged 581, respectively, 717 days in cetuximab-treated patients with or without hypomagnesemia (p = 0.101) and 576, respectively, 528 days in panitumumab-treated patients (p = 0.345). There was also no noticeable impact of hypomagnesemia presence on the average duration of therapy, which averaged 296, respectively, 259 days in cetuximab-treated patients (p = 0.683) and 271, respectively, 150 days in panitumumab-treated patients (p = 0.043).

More patients discontinued treatment due to surgery after conversion treatment with panitumumab (32.3%) than with cetuximab (8.1%); conversely, the rate of treatment discontinuation due to disease progression was higher with cetuximab (72.3% vs. 29.0%; p = 0.001).

Conclusion

In this study, panitumumab therapy in patients with metastatic primarily unresectable CRC led to longer overall survival than treatment with cetuximab. Hypomagnesemia as a therapeutic side effect was more common with panitumumab treatment but did not have a significant impact on overall survival in this study.

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Source: Kimura M., Usami E., Yoshimura T. Effects of type of antibody to EGFR and hypomagnesemia on overall Survival in first-line treatment of patients with unresectable advanced/recurrent colorectal cancer. Anticancer Res 2020; 40 (12): 7135–7140, doi: 10.21873/anticanres.14743.