Refractory hypokalemia caused by cetuximab with advanced colorectal cancer patients: the case series and literature review

Abstract

Cetuximab is the first-line treatment for advanced metastatic colon cancer. But cetuximab can cause electrolyte disturbances, including hypomagnesemia and hypokalemia. Among them, hypokalemia is often caused by hypomagnesemia, not directly caused by cetuximab. This article reports two cases of refractory hypokalemia caused by cetuximab without hypomagnesemia. The two patients had no abnormalities in serum potassium before cetuximab treatment. The occurrence of hypokalemia was clearly correlated with the cetuximab, and they were significantly improved after stopping or reducing the dose. At the same time, the appearance of hypokalemia is significantly related to the efficacy of cetuximab. They have received 37 and 35 cycles of cetuximab-related therapy, with condition stable periods of 12.8 and 15.1 months, respectively. Obviously, our report refutes the above view. In our opinion, hypokalemia, a side effect of cetuximab, may be directly caused by it, rather than secondary to hypomagnesemia. Similar to hypomagnesemia, the appearance of hypokalemia often indicates a better curative effect of cetuximab.

Fig. 1

The clinical data, changes in blood potassium, and treatment history of patient 1. (a) Changes of serum potassium and serum magnesium of patient 1. (b) Patient 1 adrenal glands have no obvious abnormalities as indicated by the red arrows. (c) Treatment timeline of patient 1. Cet, cetuximab; XELOX, Xeloda plus oxaliplatin; FOLFIRI, irinotecan, leucovorin plus fluorouracil; XELIRI, irinotecan plus Xeloda; PD, progressive disease.

Fig. 2

The clinical data, changes in blood potassium, and treatment history of patient 2. (a) Changes of serum potassium and serum magnesium of patient 2. (b) Patient 2 adrenal glands slightly enlarged on CT plain scan as indicated by the red arrows. (c) Patient 2 mineralocorticoid. (d) Treatment timeline of patient 2. mFOLFOX6, oxaliplatin, leucovorin plus fluorouracil; PD, progressive disease; SBRT, stereotactic body radiation therapy.

Fig. 3

Naranjo Algorithm Assessment. According to the results of the total score, it was divided into four grades: ‘positive’, ‘likely’, ‘possible’, and ‘suspicious’, which were used to describe the degree of causality of adverse reactions. Positive ≥ 9 points; likely 5–8 points; possible 1–4 points; suspicious ≤ 0 points.