Role of the spleen on immunosuppression in esophageal and gastric cancer

Tumor metabolic and secondary lymphoid organ metabolic markers on 18F-fludeoxyglucose positron emission tomography predict prognosis of immune checkpoint inhibitors in advanced lung cancer

BACKGROUND

The purpose of this study was to investigate the predictive value of tumor metabolic parameters in combination with secondary lymphoid metabolic parameters on positron emission tomography (PET)/computed tomography (CT) for immune checkpoint inhibitor (ICI) prognosis in advanced lung cancer.

METHODS

This study retrospectively included 125 patients who underwent 18F-fludeoxyglucose (FDG) PET/CT before ICI therapy, including 41 patients who underwent a second PET/CT scan during ICI treatment. The measured PET/CT parameters included tumor metabolism parameters [maximum standardized uptake value (SUVmax), mean standardized uptake value (SUVmean), total lesion glycolysis (TLG), and total metabolic tumor volume (TMTV)] and secondary lymphoid organ metabolism parameters [spleen-to-liver SUVmax ratio (SLR) and bone marrow-to-liver SUVmax ratio (BLR)]. The correlation of PET/CT metabolic parameters with early ICI treatment response, progression-free survival (PFS), and overall survival (OS) was analyzed.

RESULTS

Within a median follow-up of 28.7 months, there were 44 responders and 81 non-responders. The median PFS was 8.6 months (95% confidence interval (CI): 5.872-11.328), and the median OS was 20.4 months (95% CI: 15.526-25.274). Pretreatment tumor metabolic parameters were not associated with early treatment responses. The high bone marrow metabolism (BLR >1.03) was significantly associated with a shorter PFS (p = 0.008). Patients with a high TMTV (>168 mL) and high spleen metabolism (SLR >1.08) had poor OS (p = 0.019 and p = 0.018, respectively). Among the 41 patients who underwent a second PET/CT scan, the ΔSUVmax was significantly lower (p = 0.01) and the SLR was significantly higher (p = 0.0086) in the responders. Populations with low-risk characteristics (low TMTV, low SLR, and ΔSLR > 0) had the longest survival times.

CONCLUSION

High pretreatment TMTV and SLR are associated with poor OS, and increased spleen metabolism after ICI therapy predicts treatment benefit. This indicates that the combination of tumor and spleen metabolic parameters is a valuable prognostic strategy.

Preoperative Splenic Density for the Prediction of Survival and Adjuvant Chemotherapy Benefits in Gastric Cancer

Background: We aimed to determine whether splenic features change during tumor progression by evaluating the clinicopathological characteristics relevant to splenic density in patients with gastric cancer (GC) and identify a new predictive indicator of prognosis and chemotherapy benefits.

Methods: In the present analysis, 408 patients who underwent gastrectomy were included. Density was expressed in mean spleen Hounsfield units on computed tomography. Other clinical characteristics and detailed follow-up data were collected. The cutoff splenic density was 47.8 by the Xtile software. The R software was used for characteristic differential analysis in patients with different splenic densities. The Cox proportional hazards model and forest plot were used for prognosis and chemotherapy benefit analyses.

Results: Patients with low splenic density had significantly worse 3-year disease-free survival (DFS) and overall survival (OS) rates (high vs low splenic density: DFS, 63.4% vs 44.6%, p<0.001; OS, 69.8% vs 52.4%, p<0.001). Splenic density showed strong negative correlations with age, number of metastasized lymph nodes, tumor size, and depth of tumor invasion. The benefits of adjuvant chemotherapy were better in the low splenic density group (hazard ratio of OS, 0.546; p=0.001) than in the high-density group (hazard ratio of OS, 0.701; p=0.106).

Conclusions: Patients with low splenic density tended to have more advanced tumors and poor prognosis, but better chemotherapy benefits. Splenic density can be regarded as a new indicator of chemotherapy benefits and increase the accuracy of preoperative staging evaluation. Moreover, preoperative evaluation of splenic density may help establish individualized treatment strategies.

Augumentation of splenic antitumor immunity by local immunotherapy in gastric cancer patients

We previously reported that the antitumor effect of OK-432, a streptococcal preparation, was markedly augmented when this agent was injected into tumors together with fibrinogen. In order to elucidate the effect of this treatment on the spleen, we assessed splenic function in gastric cancer patients receiving preoperative local immunotherapy with OK-432 and fibrinogen. Immunohistochemical studies of the spleen at 7 days after intratumoral injection therapy revealed numerous macrophages phagocytizing OK-432 in the splenic sinuses. Phenotypic analysis of splenocytes by flow cytometry revealed an increase in the CD4/CD8 ratio and in the expression of HLA-DR, CD25, and Leu M3 by splenic T cells of the patients treated with OK-432 plus fibrinogen when compared to patients treated with OK-432 alone or untreated patients. Splenic T cells from patients treated with OK-432 plus fibrinogen showed significantly higher cytotoxicity against Daudi and K562 cells than T cells from control patients (p < 0.05), and culture of these splenic T cells with recombinant IL-2 induced the expansion of lymphokine-activated killer cells. These results demonstrate that local immunotherapy with a mixture of OK-432 and fibrinogen effectively augumented splenic antitumor immunity in gastric cancer patients.

Two-color flow cytometric analysis of splenic lymphocyte subpopulations in patients with gastric cancer

Lymphocyte subpopulations of the spleen were assayed in 26 patients with gastric cancer and 5 patients with benign disease using two-color flow cytometric analysis. The ratio of Leu 2a+.Leu 15+ cells, or suppressor T cells, in the gastric cancer patients was about 6 per cent, being higher than that in the patients with benign disease (p less than 0.05). There were fewer Leu 7+.Leu 11- cells, or natural killer-NK-cells, in the gastric cancer patients in stage III or IV than in those with stages I or II (p less than 0.05). The ratio of Leu 3a+.Leu 8- cells, or helper T cells, in the stage IV patients accounted for about 15 per cent of the splenic lymphocytes, which was less than that seen in the patients in stages I or II (p less than 0.05). The ratio of Leu 2a+.Leu 15- cells, or cytotoxic T cells, was approximately twice that of suppressor T cells. The pre-operative administration of lentinan plus OK-432 increased the ratio of Leu 4+.HLA-DR+ cells, or activated T cells, and cytotoxic T cells (p less than 0.05 and p less than 0.01, respectively). The above results suggest that lymphocyte subpopulations in the spleen may have more immunosuppressive potential in proportion with the stage of gastric cancer, but that this reduced immune state may be altered when lentinan and OK-432 are given to these patients.

Complications of infection and immunologic status after surgery for patients with esophageal cancer

Correlations between defective cell-mediated immunity (CMI) and infections following surgery for esophageal cancer were evaluated. Peripheral lymphocytes, T cells, B cells, PHA transformation, and PPD skin test were measured in 81 patients with esophageal cancer, 58 with gastric cancer, and 50 healthy controls. The depression of CMI was predominant to a similar extent in patients with esophageal cancer and in those with gastric cancer. The average level of PHA transformation immediately before surgery was significantly lower in the esophageal cancer patients with fatal septic complications than in those without such problems. Although preoperative radiation therapy markedly depressed the levels of the four parameters, this association was also noted in 28 patients not given radiation. It thus appears that PHA transformation may be valuable in the prediction of fatal septic complications after major surgery in patients with esophageal cancer.

The regulation of natural killer cell activity by splenic nonspecific suppressor cells and its modification in cancer patients

Spleen cells (SC), splenic venous blood lymphocytes (SVL) and peripheral blood lymphocytes (PBL) from gastric and esophageal cancer patients were simultaneously tested for natural killer (NK) and nonspecific suppressor (Ts) cell activities. Furthermore, the influence of Ts activity on the augmentation of NK activity by a biological response modifier (BRM) was also investigated. Positive Ts activities were frequently detected in the SC, SVL and PBL of advanced cancer patients. The NK activities of SC and SVL were maintained even in advanced cancer patients, though significantly depressed NK activities were observed in the PBL of advanced cases. Cancer patient SC, SVL and PBL with positive Ts activity showed low NK activities. Moreover, the NK activities of SVL and PBL were low in the patients with positive Ts activity in SC. The NK activity of normal control PBL was strongly augmented by interleukin 2, interferon and OK-432. These BRMs exhibited comparable capacities to augment the NK activities of SC, SVL and PBL with negative Ts activity in cancer patients, however, the effects of these agents seemed to be low in cells with a positive Ts activity. These results suggested that NK activity might be regulated by nonspecific suppressor cells and the presence of suppressor cells might affect the augmentation of NK activity through BRM in circulating blood lymphocytes and also in spleen cells.