Initial Response to Cancer Treatment Could Predict Survival Outcomes

A greater depth of tumor response (DepOR) to treatment was associated with longer progression-free survival (PFS) and overall survival (OS) in patients with non-small cell lung cancer (NSCLC) receiving an ALK inhibitor (ALKi) or an anti-PD-1 antibody (Ab), according to a recent study.

In their study, researchers analyzed data from 2 randomized controlled trials that used an ALKi and 2 randomized control trials that used an anti-PD-1 Ab. Patients were grouped according to DepOR quartiles by the percentage of maximal tumor shrinkage from 0% to 100%. Hazard ratios (HR) were calculated to determine the association between DepOR and OS and PFS.
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Among the 305 patients in the ALKi trials, 12 were in quartile 0 (no shrinkage), 39 were in 1 quartile (shrinkage of 1%-25% shrinkage), 70 were in quartile 2 (shrinkage of 26%-50%), 144 were in quartile 3 (shrinkage of 51%-75%), and 40 were in quartile 4 (shrinkage of 76%-100%). Each category of tumor reduction for these patients was associated with increases in PFS and OS. The HRs for DepOR vs PFS were 0.19, 0.11, 0.05, and 0.03 for quartiles 1 through 4, respectively, and the HRs for DepOR vs OS were 0.94, 0.56, 0.28, and 0.05 for quartiles 1 through 4, respectively.

Among the 355 patients in the PD-1 trials, 168 were in quartile 0, 70 were in quartile 1, 44 were in quartile 2, 45 were in quartile 3, and 28 were in quartile 4. The DepOR vs PFS HRs were 0.3, 0.22, 0.09, and 0.07 for quartiles 1 through 4, respectively, and DepOR vs OS HRs were 0.52, 0.47, 0.07, and 0.14 for quartiles 1 through 4, respectively. There were significant differences in PFS and OS between patients who experienced tumor reductions of 0% to 50% and those who experienced reductions of 51% to 100%, but there were no significant differences between patients within quartiles.

“Our analysis suggests a greater DepOR is associated with longer PFS and OS for patients receiving ALKi or anti-PD1 Ab,” the researchers concluded. “Overall, this suggests that DepOR may provide an additional outcome measure for clinical trials, and may allow better comparisons of treatment activity.”

—Melissa Weiss

Reference:

McCoach CE, Blumenthal GM, Zhang L, et al. Exploratory analysis of the association of depth of response and survival in patients with metastatic non-small cell lung cancer treated with a targeted therapy or immunotherapy [published online August 2, 2017]. Ann Oncol. https://doi.org/10.1093/annonc/mdx414.