Blood alkaline phosphatase predicts prognosis of patients with advanced HER2-negative gastric cancer receiving immunotherapy

Background: Immune checkpoint blockade is effective against many cancer types, but few patients achieve a complete response (OR). Therefore, effective prognostic biomarkers are needed for metastatic gastric cancer (GC) patients after immune treatment. The present study assessed the value of hematological parameters as markers of the effectiveness of immune checkpoint blockade among metastatic GC patients.

Methods: This retrospective study included patients with metastatic GC who underwent multiline chemotherapy including at least two courses of immunotherapy between September 2018 and December 2020. Patient and tumor characteristics were tested for prognostic significance by analysis of variance or chi-square test. Kaplan-Meier and Cox analyses were performed to identify factors associated with progression-free survival (PFS).

Results: Sixty-one GC patients (mean age 55.61±11.97 years, range 23-80 years, 24 females, and 37 males) were included, and 27, 9 and 25 cases had organ only, peritoneum only, and simultaneous organ and peritoneum metastasis, respectively. Gastrectomy was performed in 24 cases, and there was no operative treatment in the other 37 cases, while all patients received two or more lines of chemotherapy. After immune treatment, 13 patients achieved a partial response (PR), 16 stable disease (SD), and 32 progressive disease (PD). The median PFS was 4.93±3.47 months. An alkaline phosphatase (ALP) level >225 U/L, a lactate dehydrogenase level (LDH) >299 U/L, and a body mass index (BMI) >24 kg/m² were associated with a short PFS (P=0.01, P=0.008, and P=0.039, respectively). A Cox multivariate proportional hazard model indicated that higher ALP level was a significant prognostic indicator for adverse PFS.

Conclusions: Our data show an ALP cutoff of 225 U/L offered good prognostic sensitivity for HER2-negative metastatic GC. ALP measurement represents a convenient, cost-effective, and relatively sensitive screening tool, and prospective studies involving its evaluation in addition to other biomarkers in metastatic GC patients are indicated.