Erlotinib or gefitinib for the treatment of relapsed platinum pretreated non-small cell lung cancer and ovarian cancer: a systematic review

BACKGROUND

Platinum-based chemotherapy is the standard of care for ovarian cancer and non-small cell lung cancer (NSCLC). However, resistance to platinum agents invariably develops. Targeted therapies, such as tyrosine kinase inhibitors (TKIs), have great potential here as they exert their anti-tumour effect via alternative mechanisms to platinum-based drugs and as such may remain unaffected by emergent resistance to platinum.

METHODS

A systematic review was conducted to investigate whether two EGFR-TKIs, erlotinib and gefitinib, have efficacy in the platinum-resistance setting. Preclinical studies of platinum-resistant cancer cell lines, which had been subsequently treated with EGFR-TKIs, were sought to establish proof-of-concept. Clinical trials reporting administration of EGFR-TKIs to ovarian cancer and NSCLC patients relapsed after therapy with platinum drugs were investigated to determine sensitivity of these cohorts to EGFR-TKI treatment. The role of EGFR mutation, copy number and protein expression on response to EGFR-TKIs after failure of platinum chemotherapy were also investigated.

RESULTS

Preclinical models of platinum-resistant cancer were found which display a spectrum of cross-resistance profiles to EGFR-TKIs. Sensitivity to EGFR-TKIs is dependent on the activation of the EGFR pathway or EGFR interacting proteins such as HER-2. EGFR-TKIs show favourable response rates in platinum-pretreated NSCLC, 11.14% and 15.25% for 150mg/day erlotinib and 250mg/day gefitinib, respectively. These response rates significantly improve in patients of Asian descent (28.3% and 29.17%, respectively) and patients with EGFR activation mutations (41.6% and 63.89%, respectively) or increased copy number (33.3% and 45.45%, respectively). Gefitinib significantly outperformed erlotinib and should therefore be the EGFR-TKI of choice in platinum-pretreated relapsed NSCLC. In contrast, response rates are very poor to both erlotinib and gefitinib in platinum pretreated ovarian cancer, 0-5.9% and they should not be used in this cohort of patients. Preclinical models demonstrate that, while cross resistance can occur between platinums and EGFR-TKIs, there is not a generalised cross-resistance phenotype. Erlotinib and gefitinib are suitable for the treatment of platinum-pretreated NSCLC, particularly in patients with EGFR mutations or increases in copy number. Unfortunately, the high rates of EGFR protein overexpression in ovarian cancer are not translating to a clinically useful therapeutic target for EGFR-TKIs; EGFR mutations are rare in ovarian cancer. Newer TKIs may improve response rates in these cohorts and future clinical trials need to collect tumour biopsies from all patients to ensure the success of personalised chemotherapy.

Pharmacokinetic drug interactions with vandetanib during coadministration with rifampicin or itraconazole

BACKGROUND

Vandetanib, an inhibitor of vascular endothelial growth factor receptor 2 (VEGFR-2), epidermal growth factor receptor (EGFR), and rearranged during transfection (RET), is a developmental oncology drug, that is in part metabolized by cytochrome P450 (CYP) 3A4. Clinical studies were performed to assess the potential for 3A4 inhibitors and inducers to affect exposure to vandetanib.

OBJECTIVE

The aim of this study was to investigate the effects of a potent CYP3A4 inducer, rifampicin (Study A), and a potent CYP3A4 inhibitor, itraconazole (Study B), on the pharmacokinetics of a single 300 mg dose of vandetanib in healthy subjects.

STUDY DESIGN AND SETTING

Two phase I, randomized, open-label, two-way crossover, single-center studies.

PARTICIPANTS AND INTERVENTION

Study A: 18 healthy male subjects aged 21-44 years were randomized to receive each of the following two regimens, separated by a ≥6-week washout period: (i) oral rifampicin 600 mg/day on days 1-31 with a single oral dose of vandetanib 300 mg on day 10; and (ii) a single oral dose of vandetanib 300 mg on day 1. Study B: 16 healthy male subjects aged 20-44 years were randomized to receive each of the following two regimens, separated by a 3-month washout period: (i) oral itraconazole 200 mg/day on days 1-24 with a single oral dose of vandetanib 300 mg on day 4; and (ii) a single oral dose of vandetanib 300 mg on day 1.

MAIN OUTCOME MEASURE

Blood samples for measurement of vandetanib (both studies) concentrations and its metabolites, N-desmethylvandetanib and vandetanib N-oxide (Study A only), were collected before and at various timepoints after vandetanib administration for up to 28 days (Study A) and 37 days (Study B). Pharmacokinetic parameters were determined using non-compartmental methods. The area under the plasma concentration-time curve from time 0 to 504 hours (AUC(504)) and maximum plasma concentration (C(max)) of vandetanib were compared in the presence and absence of rifampicin, and in the presence and absence of itraconazole.

RESULTS

Study A: coadministration of vandetanib with rifampicin resulted in a statistically significant reduction in AUC(504) (geometric least square [GLS]mean ratio [vandetanib + rifampicin/vandetanib alone] 0.60; 90% CI 0.58, 0.63). There was no significant difference in C(max) of vandetanib (GLSmean ratio 1.03; 90% CI 0.95, 1.11). AUC(504) and C(max) of N-desmethylvandetanib increased by 266.0% and 414.3%, respectively, in the presence of rifampicin compared with vandetanib alone. Exposure to vandetanib N-oxide was very low compared with that of vandetanib, but was increased in the presence of rifampicin. Study B: coadministration of vandetanib with itraconazole resulted in a significant increase in AUC(504) (GLSmean ratio [vandetanib + itraconazole/vandetanib alone] 1.09; 90% CI 1.01, 1.18) and no significant change in C(max) (GLSmean ratio 0.96; 90% CI 0.83, 1.11). Vandetanib was well tolerated in both studies.

CONCLUSIONS

Exposure to vandetanib, as assessed by AUC(504) in healthy subjects, was reduced by around 40% when a single dose was given in combination with the potent CYP3A4 inducer rifampicin. Because of this, it may be appropriate to avoid coadministration of potent CYP3A4 inducers with vandetanib. Vandetanib exposure was increased by about 9% when it was taken in combination with the CYP3A4 inhibitor itraconazole. It is unlikely that coadministration of vandetanib and potent CYP3A4 inhibitors will need to be contraindicated.

Targeted therapies for non-small cell lung cancer: an evolving landscape

Over the past decade, a multitude of targeted agents have been explored in the treatment of advanced non-small cell lung cancer (NSCLC). Thus far, two broad classes of agents have been implemented in clinical practice: (a) vascular endothelial growth factor (VEGF)-directed therapies and (b) antagonists of the epidermal growth factor receptor (EGFR). In the former category, the agent bevacizumab (a monoclonal antibody) has shown landmark improvements in survival when added to cytotoxic therapy. Small molecule tyrosine kinase inhibitors (TKI) targeting the VEGF receptor (i.e., sunitinib, sorafenib, and vandetanib) show activity in phase II clinical studies. With respect to EGFR-directed therapies, the TKIs gefitinib and erlotinib have shown significant benefit, and have uncovered valuable information about the biology of lung cancer. Outside of therapies directed specifically at VEGF- and EGFR-mediated signaling, trials evaluating insulin-like growth factor-1 receptor (IGF-IR)-targeting agents, cyclooxygenase-2 (COX-2) inhibitors, c-met inhibitors, irreversible pan-HER inhibitors, mammalian target of rapamycin (mTOR) inhibitors, and histone deacetylase (HDAC) inhibitors are ongoing. Inhibitors of ALK show great promise in patients with the relevant gene translocation. Herein, the clinical development of novel therapies for NSCLC is described, including some discussion of relevant biomarkers and determination of synergy with both cytotoxic therapy and other targeted agents.

Updates in non-small cell lung cancer--insights from the 2009 45th annual meeting of the American Society of Clinical Oncology

We have reviewed the pivotal presentations in non-small cell lung cancer (NSCLC) from the 2009 annual meeting of the American Society of Clinical Oncology. We have discussed the scientific data, the impact on standards of care, and ongoing clinical trials.In patients with early-stage NSCLC, there is still no data to support the superiority of either neoadjuvant or adjuvant chemotherapy. However, adjuvant cisplatin-based chemotherapy has sustained the survival benefits after median follow-up of more than 9 years. The first-line treatment with inhibitors of epidermal growth factor receptor (EGFR) could be considered for the treatment of EGFR mutated patients with metastatic disease.Several maintenance studies with cytotoxic or biological agents have also demonstrated promising outcomes. Finally, novel targeted agents such as inhibitors of histone deacetylase and multi-targeted tyrosine kinase inhibitor have shown promising activity in NSCLC treatment.

Epidermal growth factor receptor inhibition in lung cancer: the evolving role of individualized therapy

Non-small cell lung cancer (NSCLC) is the major cause of cancer-related deaths in the USA and worldwide. Most patients present with advanced disease, and treatment options for these patients are generally limited to platinum-based chemotherapy and a few targeted therapies. Targeted agents currently in use for NSCLC inhibit oncogenic receptor tyrosine kinase pathways, such as the epidermal growth factor receptor (EGFR) pathway. While current EGFR-targeted agents, including erlotinib and gefitinib, may result in dramatic responses, they demonstrate efficacy in only a fraction of patients, and resistance to these agents frequently develops. In order to select patients most likely to benefit from blockade of EGFR pathways, investigators have focused on identifying molecular correlates of response to anti-EGFR therapy. New strategies to minimize the risk of resistance to EGFR inhibition have been employed in the development of next-generation EGFR tyrosine kinase inhibitors, such as PF00299804 and BIBW 2992; these include irreversibility of target binding, inhibition of multiple EGFR family receptors, and/or simultaneous inhibition of EGFR and other oncogenic pathways.

The role of EGFR inhibition in the treatment of non-small cell lung cancer

The identification of certain molecular mechanisms underlying lung carcinogenesis and progression has led to the development of targeted agents against different families of growth factors and receptors. The epidermal growth factor receptor (EGFR) is one such target for therapeutic exploitation. Inhibition of EGFR downstream signaling can be accomplished through two primary mechanisms: (a) the direct blocking of intracellular kinase activity with small-molecule tyrosine kinase inhibitors (TKIs) (e.g., gefitinib, erlotinib) and (b) the blocking of EGFR ligand binding using antibodies directed against the extracellular domain of the receptor (e.g., cetuximab). Resistance to available EGFR-targeted treatments has emerged as a substantial clinical issue in non-small cell lung cancer (NSCLC). Several novel agents with the potential to overcome such resistance are currently in clinical development, including irreversible EGFR TKIs, monoclonal antibodies, and TKIs directed against multiple signaling pathways. Here we discuss the clinical application of the currently available EGFR-targeted agents in NSCLC, the underlying mechanisms of resistance, and the novel agents in clinical development that may overcome resistance.