Lack of pharmacokinetic drug-drug interaction between ramucirumab and irinotecan in patients with advanced solid tumors

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.

Individualization of Irinotecan Treatment: A Review of Pharmacokinetics, Pharmacodynamics, and Pharmacogenetics

Since its clinical introduction in 1998, the topoisomerase I inhibitor irinotecan has been widely used in the treatment of solid tumors, including colorectal, pancreatic, and lung cancer. Irinotecan therapy is characterized by several dose-limiting toxicities and large interindividual pharmacokinetic variability. Irinotecan has a highly complex metabolism, including hydrolyzation by carboxylesterases to its active metabolite SN-38, which is 100- to 1000-fold more active compared with irinotecan itself. Several phase I and II enzymes, including cytochrome P450 (CYP) 3A4 and uridine diphosphate glucuronosyltransferase (UGT) 1A, are involved in the formation of inactive metabolites, making its metabolism prone to environmental and genetic influences. Genetic variants in the DNA of these enzymes and transporters could predict a part of the drug-related toxicity and efficacy of treatment, which has been shown in retrospective and prospective trials and meta-analyses. Patient characteristics, lifestyle and comedication also influence irinotecan pharmacokinetics. Other factors, including dietary restriction, are currently being studied. Meanwhile, a more tailored approach to prevent excessive toxicity and optimize efficacy is warranted. This review provides an updated overview on today’s literature on irinotecan pharmacokinetics, pharmacodynamics, and pharmacogenetics.

Ramucirumab for the treatment of metastatic gastric or gastroesophageal junction adenocarcinoma following disease progression on first-line platinum- or fluoropyrimidine-containing combination therapy in Japanese patients: a phase 2, open-label study

BACKGROUND

Ramucirumab, a monoclonal antibody vascular endothelial growth factor receptor-2 antagonist, given as monotherapy improved survival in a global phase 3 study (REGARD) of patients with gastric cancer. However, REGARD did not include Japanese patients. This study evaluated the efficacy and safety of ramucirumab monotherapy in Japanese patients with advanced gastric cancer.

METHODS

This multicenter, open-label, nonrandomized phase 2 study (Clinicaltrials.gov: NCT01983878) was performed at 16 Japanese sites. Patients with advanced gastric or gastroesophageal junction cancer after disease progression following first-line chemotherapy received intravenous ramucirumab 8 mg/kg every 2 weeks. Primary efficacy outcome: 12-week progression-free survival rate (PFS).

RESULTS

Thirty-six patients were enrolled. The 12-week PFS rate was 23.8% [90% confidence interval (CI) 12.4-37.2); the primary outcome was not met as the lower limit of the CI was outside the threshold of 16%. Median PFS was 6.6 weeks (90% CI 6.1-7.1). No patients achieved an objective response, and 11 (31%) patients achieved disease control. Median overall survival was 8.6 months (90% CI 5.7-10.7). The most frequent treatment-emergent adverse events (TEAEs) were diarrhea (9/36; 25%) and decreased appetite (8/36; 22%). Three patients reported Grade ≥ 3 ileus; all other Grade ≥ 3 TEAEs were reported by ≤ 2 patients. The most frequent adverse events of special interest (AESIs) were hypertension (10/36; 28%), bleeding/hemorrhage (7/36; 19%), and proteinuria (7/36; 19%). All Grade ≥ 3 AESIs were reported by ≤ 2 patients.

CONCLUSIONS

These findings suggest that ramucirumab monotherapy has clinical activity and a manageable safety profile in Japanese patients with gastric cancer after disease progression following first-line chemotherapy.