Cetuximab Effective in Patients With CRC After Induction Chemotherapy

Patients with metastatic colorectal cancer (mCRC) could be effectively treated after initial induction chemotherapy with maintenance therapy (MT) of cetuximab (CET) alone or CET with chemotherapy, according to a study published in Cancer Management and Research. The medication had a tolerable safety profile to go along with the improved survival benefits.

CRC is the second leading cause of cancer death in the world, with an estimated 935,000 deaths related to CRC in 2020. CET is a recombinant, chimeric immunoglobulin monoclonal antibody that has been shown to have efficacy in treating patients with mCRC. However, treating mCRC with combined MT and CET has been controversial and the consensus for an MT regimen using CET has not been reached. This study aimed to review data on the safety and efficacy of MT when primarily using CET in patients with mCRC.

Doctor displaying intestinal tract | Image credit: mi_viri - stock.adobe.com

Patients for this study were all from Qilu Hospital in Shandong University. All patients needed to have unresectable or recurrent mCRC, have wild-type RAS and RAF status, possess information on the efficacy evaluation after induction treatment, have a lesion that could be measure in 1 dimension, and have adequate hematologic, hepatic, and renal function. All patients data were collected from January 2016 to December 2020.

All patients received either MT based in CET, such as CET alone or CET with 1 of irinotecan or capecitabin, or observation. The patients received their dose of CET every 2 weeks, which amounted to 500 mg/m². Tumors were assessed after every 3 to 4 cycles of treatment.

There were 81 patients in this study who were treated with both chemotherapy and CET after induction therapy. The median age was 64 (range, 22-83) years and 75.3% were men. Left-sided primary CRC was the most common diagnosis with 96.3% of patients reporting it. Peritoneal metastasis was found in 17.3% of patients and 75.3% had a resection surgery. A total of 60.5% of patients had a partial response (PR) after induction treatment and 39.5% had stable disease (SD).

CET or CET with chemotherapy was prescribed to 75.3% of patients, of which 34.4% used CET alone and 65.6% had both. Dose reduction was found in 19.7% of patients and 60.7% of patients had to discontinue MT due to the progression of their disease; 19.7% discontinued due to adverse events.

The follow-up period was a median duration of 16.5 (range, 3.5-60.5) months. The 81 patients enrolled in the follow-up period had a median progression-free survival (PFS) of 10.5 (95% CI, 8.8-12.2) months and the PFS during MT and observation period (mnPFS) was 6.0 (95% CI, 5.0-7.0) months. PFS and mnPFS was positively associated with MT, PR/CR in induction therapy, and no peritoneal metastasis.

The PFS and nmPFS were found to be 11.4 (95% CI, 9.0-13.8) months and 6.4 (95% CI, 4.8-8.0) months respectively in the subgroup analysis of the MT group. The observation group was noticeably lower at 9.0 (95% CI, 7.7-10.3) months and 4.6 (95% CI, 3.3-5.9) months respectively. Patients who had peritoneal metastasis had a shorter mnPFS compared with those who didn’t.

Adverse events were less prevalent in patients who were treated with MT compared with induction chemotherapy, with 100% of patients reporting toxicity of any grade. MT had adverse events most commonly in grades 1 and 2 of toxicity, with grade 3 prevalence low. All treatment-related toxicities and adverse events were well tolerated. Patients more often had adverse events if they were on both CET and chemotherapy compared with CET alone, including nausea (27.5% vs 4.8%), neutropenia (42.5% vs 9.5%), and fatigue (55.0% vs 23.8%).

There were some limitations to this study. Subgroup analyses were limited to the small sample size, especially for those patients who weren’t on MT. Follow-up was short, which led to the overall survival number not being collected.

Patients who had MT based in cetuximab had improved PFS and mnPFS without severe adverse events after induction therapy. Using CET alone proved as effective as combined MT.

Reference

Xuan T, Wang Z, Meng S, Li J, Li J, Cao F, Qu L. Efficacy and safety of maintenance therapy using cetuximab in patients with metastatic colorectal cancer: retrospective study. Cancer Manag Res. 2024;16:185-197. doi:10.2147/cmar.s443666