ASCO-SITC 2019: Predicting Response to Immunotherapy in NSCLC
Posted: Thursday, March 21, 2019
Sequencing plasma circulating tumor DNA (ctDNA) may help to predict tumor response to PD-1 inhibitors in patients with advanced non–small cell lung cancer (NSCLC). Nicolas Guibert, MD, PhD, of Toulouse University Hospital, France, and colleagues presented their study findings at the 2019 American Society of Clinical Oncology (ASCO)–Society for Immunotherapy of Cancer (SITC) Clinical Immuno-Oncology Symposium in San Francisco (Abstract 103).
Plasma samples were collected and evaluated from 39 responders (progression-free survival of more than 6 months) and 47 nonresponders (progressive disease at first evaluation) before treatment with nivolumab. The ctDNA’s molecular profile as well as early kinetics were analyzed at both initial collection and after 1 month of treatment.
Detection of a targetable oncogenic driver such as EGFR or ALK was associated with progressive disease. The presence of PTEN or STK11 mutations was correlated with worse outcomes: progression-free survival of 1.5 months vs. 8 months without the mutations. However, KRAS and TP53 mutations were associated with good outcomes: progression-free survival of 11 months vs. 2 months with normal genes. These results suggest that patients with a high “immune score” (no driver mutation, PTEN/STK11 normal, KRAS/TP53 mutation) have better survival than those with a low “immune score” (driver mutation, PTEN/STK11 mutation, KRAS/TP53 normal; progression-free survival of 14 months vs. 2 months).
The molecular response could be correlated with clinical outcomes as well, they reported. Patients with an early decrease in ctDNA had a progression-free survival of 14 months compared with 2 months in those with an increase in ctDNA. Using the cutoff of 30% and 50% of plasma response increased the probability of ctDNA in predicting the response (hazard ratio = 4 and 4.17).
Disclosure: The study authors’ disclosure information may be found at coi.asco.org.
