Confounding mitigation for the exposure-response relationship of bevacizumab in colorectal cancer patients

AIMS

The exposure-response relationship of bevacizumab may be confounded by various factors, including baseline characteristics, time-dependent target engagement and recursive relationships between exposure and response, requiring effective mitigation. This study aimed to investigate the exposure-response relationships of bevacizumab in metastatic colorectal cancer (mCRC) patients while mitigating potential biases.

METHODS

Bevacizumab pharmacokinetics was described using target-mediated drug disposition modelling. Relationships between target kinetics, progression-free (PFS) and overall (OS) survivals were assessed using joint pharmacokinetic and parametric hazard function models. Both prognostic-driven and response-driven potential biases were mitigated. These models evaluated the impact of increased antigen target levels, clearance and intensified dosing regimen on survival.

RESULTS

Estimated target-mediated pharmacokinetic parameters in 130 assessed patients were baseline target levels (R0  = 8.4 nM), steady-state dissociation constant (KSS  = 10 nM) and antibody-target complexes elimination constant (kint  = 0.52 day-1 ). The distribution of R0 was significantly associated with increased baseline concentrations of carcinoembryonic antigen, circulating vascular endothelial growth factor and the presence of extrahepatic metastases. Unbound target levels (R) significantly influenced both progression and death hazard functions. Increasing baseline target levels and/or clearance values led to decreased bevacizumab unbound concentrations, increased R levels and shortened PFS and OS, while increasing bevacizumab dose led to decreased R and longer survival.

CONCLUSION

This study is the first to demonstrate the relationship between bevacizumab concentrations, target involvement and clinical efficacy by effectively mitigating potential sources of bias. Most of the target amount may be tumoural in mCRC. Future studies should provide a more in-depth description of this relationship.

Treatment patterns and direct medical costs of metastatic colorectal cancer patients: a retrospective study of electronic medical records from urban China

Objectives: To describe direct medical costs associated with each line of treatment among metastatic colorectal cancer (mCRC) patients in China.Methods: Electronic medical records between 2011 and 2016 were extracted from 12 tertiary hospitals in China for adult patients who initiated third-line treatment at least nine months before the end of data collection. Direct medical costs included costs of wards, diagnostic tests, surgical procedures, special materials, drugs and others. Costs were assessed by line of treatment, and drug costs were further breakdown for patients receiving chemotherapy alone and those receiving chemo- and biologics-combined therapy.Results: Of the 404 mCRC patients, the mean age was 55 years old and 62% were male. Oxaliplatin- and irinotecan-based regimens dominated first- and second-line treatment, respectively (44 and 37%). From first- to second- to third-line, the proportion of patients receiving targeted biologics increased from 18% at first-line and 12% at second-line to 34% at third-line; median number of treatment cycles reduced from 6 to 4 and to 2. The corresponding mean direct medical costs per person per cycle increased from $2,514 to $2,678 to $5,121. Mean drug costs per cycle increased from $2,314 to $2,673 to $4,316 among patients receiving chemotherapy alone and from $3,245 to $2,717 to $6,533 among patients receiving chemo- and biologics-combined therapy.Conclusions: Before 2017, mCRC patients in China did not receive the maximum benefits of precision medicine breakthroughs. Reduced treatment cycles and increased costs per cycle from first- to third-line suggested poor healthcare resource utilization. With earlier initiation and more treatment cycles, targeted biologics may better demonstrate their effectiveness among Chinese patients. Our findings reflected the urgent need to increase drug accessibility in China before 2017 and underscore that including innovative biologics into Chinese health insurance plans can reduce patients' economic burden and improve the management of mCRC.

Effects of a Multikinase Inhibitor Motesanib (AMG 706) Alone and Combined with the Selective DuP-697 COX-2 Inhibitor on Colorectal Cancer Cells

In the present study, we investigated the effects of motesanib (AMG 706), a multikinase inhibitor alone and in combination with DuP-697, an irreversible selective inhibitor of COX-2, on cell proliferation, angiogenesis, and apoptosis induction in a human colorectal cancer cell line (HT29). Real time cell analysis (RTCA, Xcelligence system) was used to determine the effects on colorectal cancer cell proliferation. Apoptosis was assessed with annexin V staining and angiogenesis was determined with chorioallantoic membrane model. We found that motesanib alone exerted antiproliferative, antiangiogenic and apoptotic effects on HT29 colorectal cancer cells. Combination with DUP-697 increased the antiproliferative, antiangiogenic and apoptotic effects. Results of this study indicate that motesanib may be a good choice in treatment of colorectal tumors. In addition, the increased effects of combination of motesanib with DuP-697 raise the possibility of using lower doses of these drugs and therefore avoid/minimize the dose-dependent side effects generally observed.

Endothelial Cell Proliferation and Vascular Endothelial Growth Factor Expression in Primary Colorectal Cancer and Corresponding Liver Metastases

BACKGROUND

. Colorectal carcinoma (CRC) is one of the major causes of cancer death worldwide. Data from the literature indicate differences between the proliferation rate of endothelial cells relative to the morphology growth type, possibly due to origin of specimens (autopsy material, surgery fragments) or quantification methods. Vascular endothelial growth factor (VEGF) is a factor that stimulates the proliferation of endothelial cells. It is expressed in more than 90% of cases of metastatic CRC.

AIM

The aim of this study was to evaluate the endothelial cell proliferation and VEGF expression in primary tumors and corresponding liver metastases.

MATERIALS AND METHODS

Our study included 24 recent biopsies of primary tumors and corresponding liver metastases of CRC cases. CD34/ Ki67 double immunostaining and RNA scope assay for VEGF were performed.

RESULTS

In the primary tumors analysis of VEGFmRNA expression indicated no significant correlation with differentiation grade, proliferative and non-proliferative vessels in the intratumoral and peritumoral areas. In contrast, in the corresponding liver metastases, VEGFmRNA expression significantly correlated with the total number of non- proliferative vessels and total number of vessels. CD34/ Ki67 double immunostaining in the cases with poorly differentiated carcinoma indicated a high number of proliferating endothelial cells in the peritumoral area and a low number in the intratumoral area for the primary tumor. Moderately differentiated carcinomas of colon showed no proliferating endothelial cells in the intratumoral area in half of the cases included in the study, for both, primary tumor and liver metastasis. In well differentiated CRCs, in primary tumors, a high proliferation rate of endothelial cells in the intratumoral area and a lower proliferation rate in the peritumoral area were found. A low value was found in corresponding liver metastasis.

CONCLUSIONS

The absence of proliferative endothelial cells in half of the cases for the primary tumors and liver metastases in moderately differentiated carcinoma suggest a vascular mimicry phenomenon. The mismatch between the total number of vessels and endothelial proliferation in primary tumors indicate that a functional vascular network is already formed or the existence of some mechanisms influenced by other angiogenic factors.

XELOX plus bevacizumab vs. FOLFIRI plus bevacizumab treatment for first-line chemotherapy in metastatic colon cancer: a retrospective study of the Anatolian Society of Medical Oncology

BACKGROUND

XELOX plus bevacizumab (XELOX-Bev) and FOLFIRI plus Bevacizumab (FOLFIRI - Bev) treatments are an effective strategies patients with metastatic colorectal cancer (mCRC).The aim of this study was to compare efficacy of first-line XELOX-Bev treatment vs FOLFIRI-Bev treatment for mCRC.

MATERIALS AND METHODS

A total of 409 patients with mCRC who received chemotherapy were included and divided into 2 groups. Group 1 (n=298) received XELOX-Bev and Group 2 (n=111) FOLFIRI-Bev. Comparisons were made in terms of overall (OS) and progression-free (PFS) survival, response rate (RR), and grade 3-4 toxicity.

RESULTS

Median follow-up was 11 months in Group 1 and 15 months for Group 2. Complete remission was observed in 29 (9.7%) and 2 (1.8%) patients, partial remission in 139 (46.6%) and 27 (24.5%) , stable disease in 88 (29.5%) and 49 (44.1%) and progressive disease in 42 (14.1%) and 33 (30.0%) patients in Group 1 and 2, respectively. Median OS was 25 months (range 2-57 months, 95%CI; 22.2-27.7) for Group 1 and 20 months (range 1-67 months, 95%CI; 16.8-23.1) for Group 2 (p=0.036). Median PFS was 9.6 months (range 2-36 months, 95%CI; 8.8-10.4) for Group 1 and 9 months (range 1-44 months, 95%CI; 7.4-10.5) for Group 2 (p=0.019). Objective RR was 56.4% in Group 1 and 26.1% in Group 2 (p<0.001).

CONCLUSIONS

First-line XELOX-Bev is more effective with a better response rate, prolongation of median PFS/OS, and a superior safety profile compared with FOLFIRI-Bev.