Irinotecan (CPT-11) in Triplet Combinations in Patients with Advanced Non–Small-Cell Lung Cancer: A Review and Report of a Phase I/II Trial

Results from an in vitro and a clinical/pharmacological phase I study with the combination irinotecan and sorafenib

PURPOSE

This single-centre, open-label, phase I dose-escalation study was performed to investigate the safety, pharmacokinetics (PK) and efficacy of sorafenib, a multi-kinase inhibitor, combined with irinotecan, a cytotoxic agent, in patients with advanced, refractory solid tumours.

PATIENTS AND METHODS

In an initial dose-escalation phase, patients received irinotecan 125 mg/m(2) and sorafenib 100, 200 and 400 mg twice daily (bid) (cohorts 1-3). In an extended phase, colorectal cancer (CRC) patients received fixed-dose irinotecan 140 mg and sorafenib 400 mg bid (cohort 4).

RESULTS

Thirty-four patients were treated: 20 in the dose-escalation phase (common tumour types: CRC [45%], ovarian [5%], pancreatic [5%]) and 14 patients in the CRC extension. Frequent drug-related adverse events were gastrointestinal symptoms, dermatological reactions and constitutional symptoms. The maximum tolerated dose was not reached. Generally, concomitant administration of irinotecan had no impact on the PK of sorafenib. Sorafenib 100 or 200 mg bid had no impact on the PK of irinotecan or its metabolite SN38. In contrast, sorafenib 400 mg bid significantly increased irinotecan and SN38 exposures; however, this was not associated with increased toxicities. Stable disease was achieved in 12/20 (60%) evaluable patients in cohorts 1-3, and 10/13 (77%) evaluable patients in cohort 4. A further patient from cohort 4 had a partial response of >200 days. The increase of SN38 exposure might be due to inhibition of formation of the SN38 glucuronide by sorafenib. In vitro, sorafenib strongly inhibited SN38 glucuronidation in human liver microsomes as indicated by a K(i) value of 2.7 micromol/l.

CONCLUSION

Sorafenib 400 mg bid can be combined with irinotecan 125 mg/m(2) or 140 mg for the treatment of patients with advanced, refractory solid tumours, although monitoring for toxicity is recommended.

The role of irinotecan combined with Cisplatin or Carboplatin in the treatment of advanced non-small-cell lung cancer

More than one third of all non-small-cell lung cancer (NSCLC) patients present with advanced stage IV disease with metastases or with stage IIIB disease with a malignant pleural or pericardial effusion. The prognosis for these patients remains poor despite some improvement in survival produced by 2-drug chemotherapy combinations. With the best 2-drug combinations, the expected median survival is 8-9 months and > 80% of patients die within 2 years of diagnosis. The overall response rate to the best combination is < 40% and the complete response rate is only 1%. Clearly, superior therapies are needed. The topoisomerase I inhibitors have been developed because the topoisomerase I enzyme plays a critical role in the DNA repair process. Irinotecan is a topoisomerase I inhibitor developed during the 1990s. It was initially approved in the United States for the treatment of colorectal cancer. In early trials, considerable activity was seen in both small-cell lung cancer and NSCLC. These observations led to combination studies with cisplatin. Cisplatin-based therapy had become a standard approach in both stage IV disease and in combination with chest radiotherapy in stage IIIB disease because metaanalyses of randomized trials showed that cisplatin-based therapy significantly improved survival. Randomized trials also showed that cisplatin-based therapy improved symptoms in the majority of patients and improved quality of life. In early combination studies, the irinotecan/cisplatin combination produced responses in an average of 40% of patients and produced median survival times that averaged about 10 months. In randomized trials comparing irinotecan/cisplatin to vindesine/cisplatin, the irinotecan/cisplatin combination was slightly better than irinotecan alone and vindesine/cisplatin. These encouraging results led to ongoing randomized trials comparing the 2-drug combination of irinotecan/cisplatin to other 2-drug combinations. Irinotecan has also been combined safely and effectively with carboplatin. The 2-drug combination of irinotecan/carboplatin produced results similar to those achieved with irinotecan/cisplatin. Irinotecan has also been incorporated into 3-drug combinations such as irinotecan/carboplatin/paclitaxel with encouraging results. A randomized trial comparing docetaxel/irinotecan to docetaxel/cisplatin showed similar results. Randomized trials comparing the 3-drug combination to a 2-drug combination are in progress. The irinotecan/cisplatin combination has considerable activity in the second-line setting. Randomized trials comparing this combination to docetaxel are needed. Irinotecan is an active agent in the first- and second- line therapy of NSCLC.