Interim Serum Soluble Interleukin-2 Receptor Levels Are Strongly Associated with Prognosis in Newly Diagnosis DLBCL Patients

Serum soluble interleukin-2 receptor (sIL2R) levels are often measured to evaluate the state of lymphoma. The serum sIL2R level at diagnosis has been reported to be correlated with the prognosis of diffuse large B cell lymphoma (DLBCL) patients treated with the R-CHOP regimen. However, it is unclear whether interim sIL2R levels are associated with prognosis in DLBCL. Here, we analyzed the prognostic impact of interim serum sIL2R levels in DLBCL. We retrospectively examined data for DLBCL patients who started receiving chemotherapy at the Japanese Red Cross Society Kyoto Daini Hospital between January 2012 and December 2018. All of the patients received R-CHOP-like regimens (rituximab plus pirarubicin or adriamycin, cyclophosphamide, vincristine, and prednisolone). The interim sIL2R level (I-IL2R) was defined as the value measured after the third chemotherapy cycle. I-IL2R levels of >700 U/ml were regarded as positive. The primary endpoints of this study were progression-free survival (PFS) and overall survival (OS). The unadjusted probabilities of PFS and OS were estimated using the Kaplan-Meier method. The log-rank test and multivariate Cox regression analysis were used to assess the prognostic value of each clinical variable. In total, 102 patients were enrolled. The patients' median age was 73.5 years (range, 35-88), 58 patients (56.9%) were male, and 52 (51.0%) had poor revised International Prognostic Index scores. The median follow-up time was 25.2 months (range, 3.7-88.6). Twenty-three patients (22.5%) were I-IL2R-positive (>700 U/ml). Univariate analysis revealed that I-IL2R-positivity was associated with a poor prognosis. The 3-y PFS rates of the I-IL2R-negative (700 U/ml) patients were 60.4% (95% confidence interval [95%CI], 46.2-71.9) and 37.5% (95%CI, 15.7-59.4; p