PD-L1 Levels Fail to Predict ALK Inhibitor Benefit in Lung Cancer Cohort

A new multicenter Japanese study now offers a clear, if sobering, answer: it does not. The research, published in Medical Oncology, analyzed 129 patients with advanced or recurrent ALK-positive non-small cell lung cancer treated at 13 Japanese institutions between July 2014 and December 2022. Every patient had PD-L1 levels assessed with the standard 22C3 antibody and expressed as a tumor proportion score, and every patient received at least one ALK inhibitor, most commonly alectinib.

The team, led by Ryo Sawada and Koichi Takayama, split the cohort into a low-PD-L1 group with scores below 50 percent, comprising 74 patients, and a high-PD-L1 group at or above 50 percent, comprising 55 patients. The primary question was whether PD-L1 status predicted progression-free survival on the first ALK inhibitor. It did not.

Patients with low PD-L1 expression survived a median of 29.7 months without progression, while those with high expression reached 35.0 months, a difference that produced a hazard ratio of 1.01 with a 95 percent confidence interval spanning 0.63 to 1.63 and a p-value of 0.961. In plain terms, the two curves were statistically indistinguishable. Response rates told the same story.

Tumors shrank measurably in 86.5 percent of the low-PD-L1 group and 85.5 percent of the high-PD-L1 group, with confidence intervals that overlapped almost completely and a p-value of exactly 1.00. Overall survival showed a numerical gap in the opposite direction, with median survival of 119.9 months in the low-PD-L1 group versus 76.6 months in the high-PD-L1 group, but this difference did not reach statistical significance, yielding a hazard ratio of 1.74 and a p-value of 0.095. The authors urge caution in reading anything into that survival gap.

Because the study was retrospective and the number of overall survival events was limited, the apparent difference could easily reflect chance, imbalances in patient characteristics, or follow-up patterns rather than a true biological effect. The confidence interval around the survival hazard ratio is wide, meaning the data are compatible with anything from a modest advantage for high-PD-L1 patients to a substantial disadvantage. One finding did stand out, however, and it concerns safety rather than efficacy.

Severe adverse events, graded 3 or higher, occurred in 21.8 percent of patients with high PD-L1 expression compared with just 5.4 percent of those with low expression. The study design strengthens the interpretation of the efficacy result in several ways. No patient received concurrent cytotoxic chemotherapy or immune checkpoint inhibitors while taking their first ALK inhibitor, removing a major source of confounding.

The frequency of prior systemic therapy before starting the ALK inhibitor was also similar between the two PD-L1 groups, so differences in treatment history are unlikely to explain the null finding. Why does this matter clinically? These data argue against that logic, at least for alectinib, the dominant drug in the cohort.

The tumor proportion score appears to carry no meaningful information about how well an ALK inhibitor will control the disease. The biology behind the result is also worth noting. The investigators conclude that intratumoral PD-L1 expression was not significantly associated with the efficacy of ALK inhibitor therapy in this cohort, and they call for prospective studies with larger cohorts to validate the observations, particularly the numerical survival difference and the toxicity imbalance.

The drug works just as well, on average, whether the tumor lights up for PD-L1 or not, though the possibility that high-expression tumors carry a higher risk of severe side effects deserves closer scrutiny in future trials.

Subject of Research: Association between intratumoral PD-L1 expression and efficacy of ALK tyrosine kinase inhibitors in advanced ALK-positive non-small cell lung cancer

Article Title: Effect of Intratumoral PD-L1 Expression on Treatment Efficacy of ALK Tyrosine Kinase Inhibitors for Advanced or Recurrent ALK-Positive Non-small Cell Lung Cancer

Article References: Sawada, R., Yamada, T., Goto, Y., Negi, Y., Nakao, A., Yoshimura, A., Furuya, N., Oba, T., Hibino, M., Nakatani, H., Taniguchi, H., Ohtsubo, A., Watanabe, S., Yamada, T., Chihara, Y., Kijima, T., & Takayama, K. (2026). Effect of Intratumoral PD-L1 Expression on Treatment Efficacy of ALK Tyrosine Kinase Inhibitors for Advanced or Recurrent ALK-Positive Non-small Cell Lung Cancer. Medical Oncology, 43(11), Article 357. https://doi.org/10.1007/s12032-026-03477-2

Image Credits: AI Generated

DOI: 10.1007/s12032-026-03477-2

Keywords: PD-L1, ALK inhibitors, non-small cell lung cancer, alectinib, progression-free survival, tumor proportion score, retrospective cohort, adverse events, biomarker, targeted therapy, immunotherapy, oncology