T-cell immunoglobulin and ITIM domains expression in newly diagnosed Egyptian multiple myeloma patients

Context
T-cell immunoglobulin and ITIM domains (TIGIT) is a potential immune checkpoint for natural killer (NK)-cell exhaustion in multiple myeloma (MM). Its high expression in several cancers is associated with poor outcomes. However, its role in the survival of MM patients has not yet been entirely understood.


Aims
This study aimed to assess TIGIT expression in newly diagnosed MM (NDMM) patients and its role in their survival.


Settings and design
Two study designs were applied in the current study. First a case–control study was executed. the second applied study design was an observational follow-up for NDMM patients to evaluate the survival outcome at clinical hematology unit in internal medicine department, Assiut University Hospital, Asyut governorate in Upper Egypt.


Patients and methods
For evaluating TIGIT expression on NK cells and NKT lymphocytes, 21 NDMM patients and 21 control subjects were recruited at the clinical hematology unit in Assiut University Hospital. Baseline peripheral blood samples were obtained from the studied subjects for TIGIT detection by flow cytometry (FACS CANTO ll (BD Bioscience-San Jose, California, USA, serial no V33896201978; 3lasers, 8 color) present at flow cytometry lab at South Egypt cancer institute. Follow-up for the studied MM cases was done to evaluate their survival.


Statistical analysis used
Statistical analysis was done using SPSS (statistical package for the social science; SPSS Inc., Chicago, Illinois, USA) version 22. Quantitative data were described in terms of mean ± SD/ standard error or median/range. The qualitative data were presented in the form of frequencies and percentages. Receiver operating characteristic curve analysis was used to determine the best cut-off points for TIGIT expression on NK cells and NKT cells. The survival of the patients was assessed using Kaplan–Meier survival analysis and the difference between the curves was analyzed using the log-rank test. A P value less than 0.05 is considered significant.


Results
Among the NDMM studied patients, TIGIT expression on CD16+CD56+NK dim cells was high in 61.9%, TIGIT on CD16+CD56+NK bright cells was high in nearly 43%, while TIGIT on CD16+CD56+CD3+NKT cells were high in all the studied MM patients (100%). Mean values of TIGIT expressions were significantly higher among cases compared with the controls. The Kaplan–Meier analysis revealed that TIGIT had no significant effect on patients’ survival.


Conclusions
TIGIT is highly expressed in NK, and NKT cells of NDMM patients. However, it has no considerable impact on survival.