Response rate for NSCLC
Response rate in NSCLC therapy
Response rates (RR) represent the percentage of patients whose cancer shrinks plus or the percentage of patients whose cancer disappears after treatment.
Response rates of NSCLC to the various agents are an important issue. Response to chemotherapy depends on the stage, being over 70% in stage II or III and about 40-50% in good performance stage IV. Tyrosine kinase inhibitors (TKI’s: erlotinib, gefitinib) have an RR of 15-20% overall. But in tumors with an EGFR mutation in which the therapy with TKI’s makes sense, the RR is over 70%. For bevacizumab so far no predictor of efficacy is available, and also for chemotherapy good predictors are lacking. Histology seems to matter.
In advanced stages of NSCLC, the drug regimen of single or combined treatment has great influence on response rates. Therapy with a single cytotoxic agent (e.g. cisplatin) gives a RR of about 10%. Cisplatin combined with another cytotoxic drug (paclitaxel) improves the RR (26%), whereas a combination of 3 drugs (cisplatin, paclitaxel and gemcitabine) achieves RRs of nearly 50%.
As the RR is disappointing and thus a large group of patients receives treatment without any benefit, predictors for efficacy have to be developed as available now for TKI’s. Also because therapy is very expensive (2000 euro per month for biologicals and the newest chemotherapeutic agents), this is an important issue.