Evaluation of the usefulness of protocol-based magnesium supplementation for hypomagnesemia in patients with advanced or recurrent colorectal cancer treated with panitumumab.

Purpose: Panitumumab (Pmab) is associated with a higher incidence and severity of hypomagnesemia compared to cetuximab, necessitating appropriate monitoring and management strategies. This study aimed to evaluate the efficacy of protocol-based magnesium (Mg) supplementation for treating hypomagnesemia in patients with advanced or recurrent colorectal cancer receiving Pmab.

Methods: In this retrospective study, patients with colorectal cancer treated with Pmab between October 2010 and September 2023 were divided into two groups: the pre-protocol group (n = 30) and the post-protocol group (n = 30). The incidence of hypomagnesemia was compared between the groups. The hypomagnesemia management protocol included Mg supplementation at grade 1 (< LLN-1.2 mg/dL), initially with 20 mL (1 mEq/mL) of Mg sulfate injection. If Mg levels continued to decrease despite supplementation, the dose was increased to 40 mL (1 mEq/mL).

Results: No significant difference was observed in the frequency of hypomagnesemia between the pre-protocol (56.7%, 17/30) and post-protocol (53.3%, 16/30) groups (P = 1.000). However, the incidence of grade 3 or higher hypomagnesemia was significantly lower in the post-protocol group than in the pre-protocol group (3.3%, 1/30 vs. 30.0%, 9/30; P = 0.012). The rate of deterioration from grade 1 to grade 3 or higher in patients who received Mg supplementation was significantly lower in the post-protocol group than in the pre-protocol group (6.3%, 1/16 vs. 60.0%, 9/15; P = 0.002).

Conclusion: Early Mg supplementation effectively reduced the incidence of severe hypomagnesemia, highlighting the utility of this protocol in managing hypomagnesemia in Pmab-treated patients.