Population pharmacokinetic and exposure simulation analysis for cediranib (AZD2171) in pooled Phase I/II studies in patients with cancer

VEGF pathway inhibition potentiates PARP inhibitor efficacy in ovarian cancer independent of BRCA status

Poly ADP-ribose polymerase inhibitors (PARPi) have transformed ovarian cancer (OC) treatment, primarily for tumours deficient in homologous recombination repair. Combining VEGF-signalling inhibitors with PARPi has enhanced clinical benefit in OC. To study drivers of efficacy when combining PARP inhibition and VEGF-signalling, a cohort of patient-derived ovarian cancer xenografts (OC-PDXs), representative of the molecular characteristics and drug sensitivity of patient tumours, were treated with the PARPi olaparib and the VEGFR inhibitor cediranib at clinically relevant doses. The combination showed broad anti-tumour activity, reducing growth of all OC-PDXs, regardless of the homologous recombination repair (HRR) mutational status, with greater additive combination benefit in tumours poorly sensitive to platinum and olaparib. In orthotopic models, the combined treatment reduced tumour dissemination in the peritoneal cavity and prolonged survival. Enhanced combination benefit was independent of tumour cell expression of receptor tyrosine kinases targeted by cediranib, and not associated with change in expression of genes associated with DNA repair machinery. However, the combination of cediranib with olaparib was effective in reducing tumour vasculature in all the OC-PDXs. Collectively our data suggest that olaparib and cediranib act through complementary mechanisms affecting tumour cells and tumour microenvironment, respectively. This detailed analysis of the combined effect of VEGF-signalling and PARP inhibitors in OC-PDXs suggest that despite broad activity, there is no dominant common mechanistic inter-dependency driving therapeutic benefit.

Pharmacogenetic-Based Interactions between Nutraceuticals and Angiogenesis Inhibitors

Background: Angiogenesis inhibitors (AIs) have become established as an effective cancer treatment. Whereas their interactions with antineoplastic drugs have extensively been investigated, little is known of the effect of their co-administration with nutraceuticals/dietary supplements (N/DSs), which are often self-prescribed. N/DSs comprise a wide range of products such as herbs, nutrients, vitamins, minerals, and probiotics. Assessment of their interactions with cancer drugs, particularly AIs, is hampered by the difficulty of gauging the amount of active substances patients actually take. Moreover, there is no agreement on which approach should be used to determine which N/DSs are most likely to influence AI treatment efficacy. We present a comprehensive review of the metabolic routes of the major AIs and their possible interactions with N/DSs. Methods: The PubMed and Cochrane databases were searched for papers describing the metabolic routes of the main AIs and N/DSs. Results: Data from the 133 studies thus identified were used to compile a diagnostic table reporting known and expected AI-N/DS interactions based on their metabolization pathways. AIs and N/DSs sharing the cytochrome P450 pathway are at risk of negative interactions. Conclusions: Recent advances in pharmacogenetics offer exceptional opportunities to identify prognostic and predictive markers to enhance the efficacy of individualized AI treatments. The table provides a guide to genotyping patients who are due to receive AIs and is a promising tool to prevent occult AI-N/DS interactions in poor metabolizers. N/DS use by cancer patients receiving AIs is a topical problem requiring urgent attention from the scientific community.

Clinical Pharmacokinetics and Pharmacodynamics of Cediranib

Cediranib potently and selectively inhibits all three vascular endothelial growth factor receptors (VEGFR-1, -2 and -3), and clinical studies have shown that it is effective in patients with ovarian cancer at a dose of 20 mg/day. Cediranib is absorbed moderately slowly; a high-fat meal reduced the cediranib area under the plasma concentration-time curve (AUC) by 24% and maximum plasma concentration (C _max) by 33%. Cediranib binds to serum albumin and α1-acid glycoprotein; protein binding in human plasma is approximately 95%. The cediranib AUC and C _max increase proportionally with dose from 0.5 to 60 mg, and cediranib has linear pharmacokinetics (PK) over time. Cediranib is metabolized via flavin-containing monooxygenase 1 and 3 (FMO1, FMO3) and uridine 5'-diphospho-glucuronosyltransferase (UGT) 1A4. Cediranib and its metabolites are mainly excreted in faeces (59%), with <1% of unchanged drug being excreted in urine. The apparent oral clearance is moderate and the mean terminal half-life is 22 h. Cediranib is a substrate of multidrug resistance-1 (MDR1) protein (also known as P-glycoprotein [P-gp]). Coadministration with ketoconazole, a potent P-gp inhibitor, increases cediranib AUC at steady-state (AUC_ss) in patients by 21%, while coadministration with rifampicin, a potent inducer of P-gp, decreases cediranib AUC_ss by 39%. Administration of cediranib with chemotherapies demonstrated minimal PK impact on each other. No dose adjustment is recommended for patients with mild or moderate hepatic or renal impairment, and no dose adjustment is needed on the basis of age and body weight. A pooled analysis at doses of 0.5-60 mg showed no significant increase in QTc intervals. Increases in blood pressure and the incidence of diarrhoea were associated with increased cediranib dose and systemic exposure.

Population exposure-safety analysis of cediranib for Phase I and II studies in patients with cancer

AIMS

A multistudy analysis of cediranib, a potent, selective inhibitor of all three vascular endothelial growth factor receptors (VEGFR-1, -2 and -3), was conducted to establish population exposure-safety models for the relationship of cediranib exposure to the safety endpoints, diastolic and systolic blood pressure (DBP and SBP) and diarrhoea in cancer patients. These models were applied to predict safety outcomes for different cediranib dose regimens.

METHODS

Models for hypertension and diarrhoea were constructed based on data from 10 Phase I and three Phase II studies comprising 631 cancer patients following cediranib once-daily oral dosing. Daily DBP and SBP were simultaneously characterized using indirect response models for predicted cediranib concentration-time courses, while daily diarrhoea events were modelled as ordered categorical variables with a proportional odds model with a Markov element for predicted average cediranib concentrations.

RESULTS

For 20 mg cediranib once-daily oral administration, the mean increase in DBP and SBP was predicted to be 7 (95% CI 3-13) and 8 mmHg (95% CI 3-16), respectively, while the probability of mild diarrhoea, but not the severity, was predicted to increase over time. Severe diarrhoea was predicted to be resolved rapidly upon discontinuation of cediranib treatment.

CONCLUSIONS

Maximum blood pressure increase was observed within the first few days of cediranib treatment, consistent with the pharmacokinetic profile of cediranib reaching steady state in about 5 days. The probability of diarrhoea increased with cediranib concentration but was far more dependent on the status of diarrhoea predicted on the previous day.

Population pharmacokinetic and exposure simulation analysis for cediranib (AZD2171) in pooled Phase I/II studies in patients with cancer

AIMS

A population pharmacokinetic (PK) model was developed for cediranib to simulate cediranib exposure for different doses, including comedication with strong uridine glucuronosyl transferase/P-glycoprotein inducers such as rifampicin, in cancer patients.

METHODS

Plasma concentrations and covariates from 625 cancer patients after single or multiple oral cediranib administrations ranging from 0.5 to 90 mg in 19 Phase I and II studies were included in the analysis. Stepwise covariate modelling was used to develop the population PK model. The final model was used to simulate cediranib exposure in cancer patients to evaluate cediranib target coverage and the need for dose adjustment for covariates or coadministration with rifampicin.

RESULTS

A two-compartment model with sequential zero- and first-order absorption and first-order elimination adequately described the cediranib concentration-time courses. Body weight and age were identified as having statistically significant impact on cediranib PK, but only <21% impact on AUC and maximum concentrations. Simulated lower bounds of 90% prediction interval or median of unbound cediranib concentrations after cediranib 15 or 20 mg exceeded the IC₅₀ for vascular endothelial growth factor receptors-1, -2 and -3. Exposures of cediranib 20 or 30 mg with coadministration of rifampicin were comparable to those of 15 or 20 mg, respectively, without coadministration.

CONCLUSIONS

No covariate was identified to require dose adjustment for cediranib. Cediranib exposure following 15 or 20 mg daily dose administration is adequate overall for inhibition of in vitro estimated vascular endothelial growth factor receptor-1, -2 and -3 activities. An increase in cediranib dose may be needed for cediranib coadministered with strong uridine glucuronosyl transferase/P-glycoprotein inducers such as rifampicin.