Safety and CSF distribution of high-dose erlotinib and gefitinib in patients of non-small cell lung cancer (NSCLC) with brain metastases.

PURPOSE

Patients of non-small cell lung cancer (NSCLC) with brain metastases have limited treatment options. High-dose erlotinib (HDE) and gefitinib (HDG) have been tried in the past. This study investigates the cerebrospinal fluid (CSF) disposition and safety of both, high-dose erlotinib and gefitinib regimens.

METHODS

Eleven and nine patients were treated with erlotinib and gefitinib, respectively. All patients received 1 week of standard dose of erlotinib (150 mg OD) or gefitinib (250 mg OD), followed by the high dose (1500 mg weekly for erlotinib and 1250 mg OD for gefitinib) from day 8. Blood and CSF samples were collected on days 7 and 15, 4 h after the morning dose and drug levels determined using LC-MS/MS. Adverse events were documented as per CTCAE 4.03 till day 15.

RESULTS

Pulsatile HDE and daily HDG resulted in 1.4- and 1.9-fold increase in CSF levels, respectively. A constant 2% CSF penetration rate was observed across both doses of erlotinib, while for gefitinib the penetration rate for high dose was half that of the standard dose suggesting a nonlinear disposition. Three patients on HDE treatment discontinued treatment after the first dose due to intolerable toxicities, whereas HDG was better tolerated with no treatment discontinuations. Since CSF disposition of gefitinib followed saturable kinetics, a lower dose of 750 mg was found to achieve CSF concentrations comparable to that of the 1250 mg dose.

CONCLUSIONS

HDG was better tolerated than HDE. CSF disposition of gefitinib was found to be saturable at a higher dose. Based on these findings, the dose of 750 mg OD should be considered for further evaluation in this setting.