Can erlotinib be used at a reduced dose to treat EGFR-mutated advanced non-small cell cancer?

This study was carried out to look at the use of a reduced dose of erlotinib (Tarceva) in the treatment of EGFR-mutated advanced non-small cell lung cancer (NSCLC). The authors found that lower-dose erlotinib was as effective as standard dose gefitinib (Iressa) in these patients.

NSCLC is the most common form of lung cancer. NSCLC is responsible for around 85% of all lung cancer diagnoses. Treatment for NSCLC is usually chemotherapy, radiotherapy, and surgical removal of tumors. Despite this, NSCLC can be difficult to treat. Epidermal growth factor receptor (EGFR)-positive NSCLC means that tumors have on their surface a protein (EGFR) that causes excess growth of cancer cells. 

Erlotinib and gefitinib are targeted therapies against the EGFR protein. These slow the growth of cancerous cells that are EGFR-positive. Erlotinib can be highly toxic at standard doses (150 mg per day). Previous studies have not indicated the effectiveness of erlotinib when it is used at a reduced dose.

There were 157 patients with EGFR-positive advanced NSCLC involved in this trial. 74 patients received lower dose erlotinib (100 mg/day) and 83 received standard-dose gefitinib (250 mg/day). The average follow-up for this trial was 21.4 months. 

91% in the erlotinib group experienced disease control (DCR; tumor shrinks in response to treatment or stops growing). This was compared to 93% of the patients in the gefitinib group. 62% in the erlotinib group and 53% in the gefitinib group responded to treatment. Response to treatment lasted a shorter amount of time with erlotinib (7.7 months) compared to geftinib treatment (10.6 months).

There was no significant difference in survival without disease progression between both groups (10.1 months with erlotinib and 11.3 months with geftinib). The average overall survival of patients was also similar between both groups (26.6 months with erlotinib and 28.7 months with geftinib). 

Overall, there were no significant differences in side effects between the 2 groups. Patients in the gefitinib experienced more serious side effects (13%) compared to 5% of the erlotinib group. 12 patients in the gefitinib group stopped therapy due to side effects such as liver damage, rash and mouth sores compared to 3 patients in the erlotinib group who stopped treatment due to skin reactions. 

The authors found that lower-dose erlotinib (100 mg/d) was as effective as standard-dose gefitinib (250 mg/d) in treating EGFR-mutated advanced NSCLC. 

This trial included a small number of participants. Larger studies are needed.