PD-L1 Expression Linked to Survival in Unresectable/Recurrent Gastric Cancer Chemotherapy Analysis
An ancillary analysis of a phase III trial evaluates the prognostic value of different PD-L1 scoring methods in patients treated with chemotherapy alone.
Key takeaways
- An ancillary analysis of the JCOG1013 trial evaluated PD-L1 expression in 540 patients with unresectable/recurrent gastric cancer.
- A tumor proportion score (TPS) of 1% or greater was significantly associated with longer overall survival and progression-free survival.
- A combined positive score (CPS) of 5 or greater did not show a significant association with survival outcomes.
- TPS may serve as an independent favorable prognostic factor for patients receiving chemotherapy alone.
Researchers evaluating gastric cancer markers have identified a potential prognostic indicator for patients with unresectable/recurrent gastric cancer undergoing standard chemotherapy. In an ancillary analysis of a phase III clinical trial, published in the British Journal of Cancer in September 2026, investigators evaluated the prognostic value of PD-L1 expression in patients who did not receive immunotherapy.
The original trial, JCOG1013 (clinical trial registration UMIN000007652), compared two chemotherapy regimens for unresectable/recurrent gastric cancer and demonstrated no overall survival or progression-free survival benefit of docetaxel, cisplatin, and S-1 over cisplatin and S-1. This ancillary analysis, designated JCOG1013A1, evaluated the prognostic value of PD-L1 expression in these patients.
The prognostic significance of PD-L1 expression in unresectable/recurrent gastric cancer treated by first-line chemotherapy without an immune checkpoint inhibitor has remained unclear. This analysis reveals the prognostic value of PD-L1 expression for survival in patients treated with chemotherapy alone.
What Happened
In this ancillary analysis, researchers evaluated pretreatment tumor specimens from 540 of the 741 patients originally enrolled in the JCOG1013 phase III trial. PD-L1 expression was assessed using the Dako 28-8 pharmDx assay. Investigators calculated two metrics: the combined positive score (CPS) and the tumor proportion score (TPS).
PD-L1 positivity was defined as a CPS of 5 or greater, or a TPS of 1% or greater. The researchers then conducted univariable and multivariable analyses to evaluate the association between these scores and overall survival (OS) as well as progression-free survival (PFS).
What The Evidence Shows
In univariable analyses, neither a CPS of 5 or greater nor a TPS of 1% or greater was significantly associated with overall survival or progression-free survival.
In multivariable analyses, the two metrics showed different results:
A CPS of 5 or greater was not significantly associated with overall survival (hazard ratio [HR] 0.86, 95% confidence interval [CI] 0.71-1.04; p = 0.127) or progression-free survival (HR 0.92, 95% CI 0.77-1.11; p = 0.392).
However, a TPS of 1% or greater was significantly associated with longer overall survival (HR 0.78, 95% confidence interval [CI] 0.62-0.97; p = 0.028) and longer progression-free survival (HR 0.76, 95% confidence interval [CI] 0.62-0.94; p = 0.012).
What We Don't Know Yet
While the analysis identifies a TPS of 1% or greater as an independent favorable prognostic factor, it represents an ancillary analysis of the JCOG1013 trial, evaluating a subset of 540 patients out of the 741 originally enrolled. Additionally, because the trial evaluated chemotherapy regimens without immune checkpoint inhibitors, these findings do not address how these markers would perform in patients receiving immunotherapy.
What Comes Next
Whether these results can be replicated in other cohorts is an open question. Additionally, the biological mechanisms explaining why a TPS of 1% or greater correlates with survival outcomes, while CPS does not, remain to be determined.
What This Means
The results suggest that a TPS of 1% or greater acts as an independent favorable prognostic marker for survival in patients with unresectable/recurrent gastric cancer undergoing chemotherapy alone. This indicates that measuring TPS may carry distinct prognostic value in patients who do not receive immune checkpoint inhibitors, whereas CPS did not show a statistically significant prognostic relationship in this setting.
Original Source
British Journal of Cancer (September 2026): "PD-L1 expression and survival in unresectable/recurrent gastric cancer treated by 1st-line treatment without immune checkpoint inhibitors: JCOG1013A1." PMID: 42697937.
Questions readers ask
- What did the JCOG1013A1 study evaluate?
- It evaluated the prognostic value of PD-L1 expression using CPS and TPS in patients with unresectable/recurrent gastric cancer treated with first-line chemotherapy without an immune checkpoint inhibitor.
- Did TPS or CPS show a stronger association with survival?
- In multivariable analyses, a TPS of 1% or greater was significantly associated with longer overall survival (p=0.028) and progression-free survival (p=0.012), while a CPS of 5 or greater was not significantly associated with either outcome.
What this means
A TPS of 1% or greater serves as an independent favorable prognostic marker for survival in patients with unresectable/recurrent gastric cancer receiving chemotherapy alone. Conversely, a CPS of 5 or greater did not show a statistically significant prognostic relationship with survival in this setting.
Limitations and uncertainties
- This study is an ancillary analysis of a subset of patients (540 out of 741) from the JCOG1013 trial. The findings are limited to patients receiving first-line chemotherapy alone without immune checkpoint inhibitors.
