Adding aggressive local radiotherapy to treatment with tyrosine kinase inhibitor (TKI) significantly improved progression-free and overall survival in patients with previously untreated, EGFR-mutated, oligometastatic non–small cell lung cancer (NSCLC) in a phase 3 trial presented as part of the American Society of Clinical Oncology virtual scientific program.
Sixty-eight patients were randomized at diagnosis to receive a first-generation TKI plus stereotactic body radiation therapy (SBRT) to all disease sites. The other 68 patients were randomized to receive a TKI alone, but 3 patients were lost follow-up and not included in the analysis. The TKIs used were gefitinib, erlotinib, and icotinib.
At baseline, patients had a maximum of two lesions in any one organ and no more than five metastases overall. Patients with brain metastases were excluded.
The median progression-free survival was 20.2 months in the SBRT arm and 12.5 months in the TKI-only arm (hazard ratio, 0.618; P < .001). The median overall survival was 25.5 months and 17.4 months, respectively (HR, 0.682; P < .001).
There were no grade 4/5 adverse events nor any statistically significant between-group differences in grade 3 events.
‘Compelling’ data with caveats
The study results suggest that “aggressive local therapy to sites at diagnosis should be explored further in large cohort phase 3 trials as a standard treatment option in this clinical scenario,” said investigator Xiao-shan Wang, MD, PhD, of the University of Electronic Science and Technology of China and Sichuan Provincial People’s Hospital in Chengdu.
“The data are compelling,” Dr. Wang added. “As we attempt to maximize the benefits of EGFR-directed targeted therapies, we are likely going to be moving away from a sequentially administered approach to treatment and considering combinations.”
The new findings, combined with prior phase 2 results, support “incorporation of upfront SBRT with TKI into practice for selected patients with oligometastatic disease, with the open question remaining of how many metastases are too many,” said study discussant Rachel Sanborn, MD, of Providence Cancer Institute Franz Clinic in Portland, Ore.
However, “it’s important to make note of the baseline characteristics of the patients enrolled,” she said.
Twelve percent of patients in the control arm and 4% of those in the SBRT group had EGFR exon 20 insertions. This “imbalance could have negatively impacted the outcomes in the TKI-alone arm,” Dr. Sanborn said.
Also, a higher proportion of patients in the TKI-alone arm received gefitinib, and “there was no information offered on second-line therapies in the study, which might have also affected outcomes,” Dr. Sanborn added.
Additional details
The study (NCT02893332) enrolled NSCLC patients with a life expectancy of at least 6 months and an Eastern Cooperative Oncology Group performance status score of 0-2. NSCLC was confirmed by pathology and EGFR mutations by gene sequencing.
The radiation dose was 25-40 Gy in five fractions. Gefitinib was used in 47% of patients in the SBRT arm and 58% of the control group. Erlotinib was used in 44% of the SBRT arm and 35% of controls. Icotinib was used by less than 10% of patients in each group.
Grade 3 skin rash occurred in 50% of patients in the SBRT arm and 62% of those in the TKI-alone arm. Grade 3 pneumonitis occurred in 30% and 15%, respectively. Grade 3 esophagitis occurred in 15% of patients in both arms.
One patient in the TKI arm had severe liver injury. One patient in the SBRT arm fractured a rib, which was considered probably related to the radiation.
Multivariate analysis revealed that, in addition to SBRT, lower baseline performance status score (0 vs. 1-2) and fewer metastases (<2 vs. ≥3) were protective for progression-free survival. Lower performance scores, fewer metastases, lower T stage (T1-2 vs. T3-4), and exon 19 versus exon 20 and 21 mutations were protective for overall survival.
The study arms were well balanced at baseline. The mean patient age was 66.9 years in the SBRT arm and 63.32 years in the TKI-only arm. In both arms, most patients were women (63% and 60%, respectively).
The study was sponsored by Sichuan Provincial People’s Hospital. The investigators and Dr. Sanborn have no relevant disclosures.
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SOURCE: Wang X et al. ASCO 2020, Abstract 9508.