Efficacy and safety of regorafenib in the treatment of metastatic colorectal cancer: a retrospective cohort study.

Background: The majority of studies of regorafenib now were small-sample and single-arm, which potentially limits the strength of evidence. We conduct the study to identify the efficacy and safety of regorafenib for patients with metastatic colorectal cancer (mCRC) in real-world applications. Methods: mCRC patients who underwent regorafenib second line or post-second line treatment with at least one assessable lesion were analyzed. Patients received different doses of regorafenib and different combination regimens. The patients were followed up with laboratory tests and imaging examinations every 3 months to evaluate the efficacy and adverse events (AEs). The primary endpoint of this study was median overall survival (mOS), and the secondary endpoints were median progression-free survival (mPFS), the objective response rate (ORR), the disease control rate (DCR), and AEs. Results: A total of 77 patients (45 males and 32 females, aged 58.80±11.65 years) were enrolled in the study. Most primary tumors were located in the rectum (59.74%), and the vast majority of tumors (89.62%) had an adenocarcinoma histological type. The 77 patients had an mOS of 17.8 months, a progression-free survival (PFS) of 4.63 months, an ORR of 6.76%, and a DCR of 55.41%. Patients underwent regorafenib third-line therapy had significantly higher overall survival (OS) than those underwent regorafenib post- third-line treatment (P=0.03). The neutrophil to lymphocyte ratio (NLR) was an independent factor affecting the OS of the mCRC patients [hazard ratio (HR) =1.12, P=0.03]. In both univariate and multivariate analyses, discontinued use of regorafenib after progression reduced patients' PFS (HR =3.07, P<0.001; HR =2.78, P=0.007). In terms of the tolerated dose, patients receiving 120 mg regorafenib had the longest OS numbers, but there was no statistical difference. We analyzed the effect of the baseline NLR on the OS of patients receiving regorafenib combined with immunotherapy, and found that the NLR ratio cut-off value was 4.4, and patients with a NLR ratio ≤4.4 benefited significantly in terms of OS (P=0.03). The AEs included 21 (27.27%) cases of hand and foot skin reaction, 15 (19.48%) cases of fatigue, 9 (11.69%) cases of pain, 9 (11.69%) cases of nausea, 9 (11.69%) cases of fever, 9 (11.69%) cases of cough, and so on. Conclusions: Regorafenib is relatively effective and safe as a third-line and posterior treatment of mCRC. Patients underwent regorafenib third-line therapy had longer OS than those underwent regorafenib post- third-line treatment. Moreover, PFS benefits can still be obtained by continuing regorafenib treatment after progression. Grade 1-2 AEs were common, but these were usually tolerated by most patients.