Pharmacokinetics, safety, and efficacy of FOLFIRI plus bevacizumab in Japanese colorectal cancer patients with UGT1A1 gene polymorphisms

Development and Application of Physiologically-Based Pharmacokinetic Model to Predict Systemic and Organ Exposure of Colorectal Cancer Drugs

BACKGROUND/OBJECTIVES

Colorectal cancer (CRC) holds the third and second position among cancers affecting men and women, respectively. Frequently, the first-line treatment for metastatic CRC consists of the intravenous administration of 5-fluorouracil and leucovorin in combination with oxaliplatin or irinotecan. Physiologically-based pharmacokinetic models (PBPK) aim to mechanistically incorporate body physiology and drug physicochemical attributes, enabling the description of both systemic and organ drug exposure based on the treatment specificities. This bottom-up approach represents an opportunity to personalize treatment and minimize the therapeutic risk/benefit ratio through the understanding of drug distribution within colorectal tissue. This project has the goal of characterizing the systemic and tissue exposure of four anti-cancer drugs in humans using a PBPK platform fed with data from the literature.

METHODS

A literature search was performed to collect clinical data on systemic concentration versus time profiles. Physicochemical features were obtained from the literature, as well as parameters associated with distribution, metabolism, and excretion. The PBPK models were built using PK-Sim®.

RESULTS

The data from 51 clinical studies were extracted and combined in one single dataset. The PBPK models successfully described the exposure vs. time profiles with respect to both, with both the typical tendency and dispersion shown by the data. The percentage of observations falling within the two-fold error bounds ranged between 94 and 100%. The colon/plasma AUCinf ratios were similar for 5-FU, oxaliplatin, and leucovorin, but it was significantly higher for irinotecan.

CONCLUSIONS

The PBPK models support tailored treatment approaches by linking in vitro studies to organ exposure. These models serve as the initial step towards incorporating a dedicated tumor compartment, which will further account for the variability in tumor microenvironment characteristics to improve therapeutic strategies.

A Pilot Study of Silymarin as Supplementation to Reduce Toxicities in Metastatic Colorectal Cancer Patients Treated With First-Line FOLFIRI Plus Bevacizumab

Irinotecan, a topoisomerase inhibitor, is a common cytotoxic agent prescribed for metastatic colorectal cancer (mCRC) patients. Diarrhea is the most common adverse event (AE). The underlying mechanism of irinotecan-induced diarrhea is intestinal mucosal damage caused by SN-38 (active metabolite of irinotecan) hydrolyzed from SN-38G (inactive metabolite) by bacterial -glucuronidase (G). According to an animal study, silymarin reduces the activity of bacterial G without impairing antitumor efficacy. We conducted a prospective open-label pilot study to evaluate the effect of silymarin as supplementation in reducing toxicities of mCRC patients undergoing irinotecan-based chemotherapy. We enrolled and randomized 70 mCRC patients receiving first-line FOLFIRI (5-fluorouracil/leucovorin/irinotecan) plus bevacizumab. In each treatment cycle, the study group was administered silymarin capsules (150 mg) three times daily for 7 days. The study group experienced less AEs in diarrhea (5.7% vs. 14.6%, p=0.002) and nausea (27.0% vs. 40.2%, p=0.005) in comparison with the control group, but no significant differences in hepatic toxicities were observed. In conclusion, simultaneous administration of silymarin is a potential effective supplementation for reducing toxicities in mCRC patients undergoing first-line FOLFIRI plus bevacizumab, especially in diarrhea and nausea.

Safety and Tolerability of Anti-Angiogenic Protein Kinase Inhibitors and Vascular-Disrupting Agents in Cancer: Focus on Gastrointestinal Malignancies

Angiogenesis is an essential process for tumor growth and metastasis. Inhibition of angiogenesis as an anticancer strategy has shown significant results in a plethora of tumors. Anti-angiogenic agents are currently part of many standard-of-care options for several metastatic gastrointestinal cancers. Bevacizumab, aflibercept, ramucirumab, and regorafenib have significantly improved both progression-free and overall survival in different lines of treatment in metastatic colorectal cancer. Second-line ramucirumab and third-line apatinib are effective anti-angiogenic treatments for patients with metastatic gastric cancer. Unfortunately, the anti-angiogenic strategy has major practical limitations: resistance inevitably develops through redundancy of signaling pathways and selection for subclonal populations adapted for hypoxic conditions. Anti-angiogenic agents may be more effective in combination therapies, with not only cytotoxics but also other emerging compounds in the anti-angiogenic class or in the separate class of the so-called vascular-disrupting agents. This review aims to provide an overview of the approved and "under development" anti-angiogenic compounds as well as the vascular-disrupting agents in the treatment of gastrointestinal cancers, focusing on the actual body of knowledge available on therapy challenges, pharmacodynamic and pharmacokinetic mechanisms, safety profiles, promising predictive biomarkers, and future perspectives.

Targeting CRMP-4 by lentivirus-mediated RNA interference inhibits SW480 cell proliferation and colorectal cancer growth

The aim of the present study was to investigate the expression level of collapsin response mediator protein 4 (CRMP-4) in human colorectal cancer (CRC) tissue and to evauluate its impact on SW480 cell proliferation, in addition to tumor growth in a mouse xenograft model. Clinical CRC tissue samples were collected to detect the CRMP-4 protein expression levels using western blot and immunohistochemistry analyses. A specific small interfering RNA sequence targeting the CRMP-4 gene (DPYSL3) was constructed and transfected into an SW480 cell line using a lentivirus vector to obtain a stable cell line with low expression of CRMP-4. The effectiveness of the interference was evaluated using western blot and reverse transcription-quantitative polymerase chain reaction, and the cell proliferation was determined using MTT and BrdU colorimetric methods. Tumor growth was assessed by subcutaneously inoculating the constructed cells into BALB/c nude mice. The protein expression levels of CRMP-4 were markedly increased in colon tumor tissue of the human samples. The proliferation of SW480 cells and the tumor growth rate in nude mice of the si-CPMR-4 group were evidently depressed compared with the si-scramble group. Thus, the present results suggest that CRMP-4 may be involved in the pathogenesis of CRC.

Genotype-Guided Dosing Study of FOLFIRI plus Bevacizumab in Patients with Metastatic Colorectal Cancer

Purpose:UGT1A1*28 confers a higher risk of toxicity in patients treated with irinotecan. Patients with *1/*1 and *1/*28 genotypes might tolerate higher than standard doses of irinotecan. We aimed to identify the MTD of irinotecan in patients with metastatic colorectal cancer (mCRC) with *1/*1 and *1/*28 genotypes treated with FOLFIRI plus bevacizumab, and to determine whether bevacizumab alters irinotecan pharmacokinetics.Experimental Design: Previously untreated patients with mCRC (25 *1/*1; 23 *1/*28) were given FOLFIRI plus bevacizumab every 2 weeks. The irinotecan dose was escalated using a 3 + 3 design in each genotype group as follows: 260, 310, and 370 mg/m² The MTD was the highest dose at which <4/10 patients had a dose-limiting toxicity (DLT). Pharmacokinetics of irinotecan and SN-38 were measured on days 1 to 3 (without bevacizumab) and 15 to 17 (with bevacizumab).Results: For *1/*1 patients, 2 DLTs were observed among 10 patients at 310 mg/m², while 370 mg/m² was not tolerated (2 DLTs in 4 patients). For *1/*28 patients, 2 DLTs were observed among 10 patients at 260 mg/m², while 310 mg/m² was not tolerated (4 DLTs in 10 patients). Neutropenia and diarrhea were the most common DLTs. Changes in the AUCs of irinotecan and SN-38 associated with bevacizumab treatment were marginal.Conclusions: The MTD of irinotecan in FOLFIRI plus bevacizumab is 310 mg/m² for UGT1A1 *1/*1 patients and 260 mg/m² for *1/*28 patients. Bevacizumab does not alter the pharmacokinetics of irinotecan. The antitumor efficacy of these genotype-guided doses should be tested in future studies of patients with mCRC treated with FOLFIRI plus bevacizumab. Clin Cancer Res; 23(4); 918-24. ©2016 AACR.

Predictive and prognostic markers in the treatment of metastatic colorectal cancer (mCRC): personalized medicine at work

This article clarifies prognostic and predictive markers in the treatment of colorectal cancer. Multiple chemotherapeutic drugs are approved for metastatic colorectal cancer (mCRC), but available guidelines are often not helpful in directing drug selections. It would be desirable to define patient populations before chemotherapy by biomarkers that predict outcome and toxicities. RAS mutational evaluation remains the only established biomarker analysis in the treatment of mCRC. BRAF mutant tumors are associated with poor outcome. Chemotherapeutic combination therapies still remain the most active treatments in the armamentarium, and future trials should address the need to prospectively investigate and validate biomarkers.

Germline TYMS genotype is highly predictive in patients with metastatic gastrointestinal malignancies receiving capecitabine-based chemotherapy

PURPOSE

This work was initiated to extend data on the effect of pharmacogenetics and chemotherapy pharmacokinetics (PK) on clinical outcome in patients with gastrointestinal malignancies.

METHODS

We assessed 44 gene polymorphisms in 16 genes (TYMS, MTHFR, GSTP1, GSTM1, GSTT1, DPYD, XRCC1, XRCC3, XPD, ERCC1, RECQ1, RAD54L, ABCB1, ABCC2, ABCG2 and UGT2B7) in 64 patients with metastatic colorectal cancer (CRC) receiving capecitabine/oxaliplatin and 76 patients with advanced gastroesophageal cancer (GEC) receiving epirubicin/cisplatin/capecitabine, respectively. Plasma concentrations of anticancer drugs were measured for up to 24 h, and results were submitted to population PK analysis. We calculated the association between gene polymorphisms, chemotherapy exposure, tumor response, progression-free survival (PFS), overall survival (OS) and chemotherapy-related toxicity using appropriate statistical tests.

RESULTS

Patients with a low clearance of 5FU were at increased risk of neutropenia (P < 0.05) and hand-foot syndrome (P = 0.002). DPYD T85C, T1896C and A2846T mutant variants were associated with diarrhea (P < 0.05) and HFS (P < 0.02), and IVS14+1G>A additionally with diarrhea (P < 0.001). The TYMS 2R/3G, 3C/3G or 3G/3G promoter variants were associated with worse PFS in the CRC (HR = 2.0, P < 0.01) and GEC group (HR = 5.4, P < 0.001) and worse OS in the GEC group (HR = 4.7, P < 0.001). The GSTP1 A313G mutant variant was associated with a higher PFS (HR = 0.55, P = 0.001) and OS (HR = 0.60, P = 0.002) in the CRC group.

CONCLUSIONS

Germline polymorphisms of DPYD, TYMS and GSTP1 have a significant effect on toxicity and clinical outcome in patients receiving capecitabine-based chemotherapy for advanced colorectal or gastroesophageal cancer. These data should further be validated in prospective clinical studies.