Expression of Hypoxia-Inducible Factor (HIF) Is An Independent Favorable Prognostic Factor in Diffuse Large B-Cell Lymphoma (DLBCL) Treated with R-CHOP
Authors: Evens Andrew M. , Sehn Laurie H. , Farinha Pedro , Schumacker Paul T , Raji Adekunle , Lu Yi , Nelson Beverly P. , Gascoyne Randy D. , Gordon Leo I. 
Published: April 2020

Abstract
HIF is a transcription factor that regulates gene expression in response to decreases in cellular oxygenation (hypoxia). Genes activated by HIF are involved in glycolysis, glucose transport, angiogenesis, cell proliferation, cell migration, cell metabolism, and cell survival. Many of these genes confer protection against the consequences of oxygen deprivation while others enhance resistance to chemotherapy or radiotherapy. Clinically, evidence of elevated HIF protein correlates with poor prognosis in lung, breast, colorectal, brain, pancreatic, ovarian, renal, and bladder cancers. Our preliminary tissue micro array (TMA) data suggested that HIF is frequently stabilized in lymphoma (BJH2008; 141:676), especially among patients with diffuse large B-cell lymphoma (DLBCL). We also found that constitutive expression of HIF-1α and/or HIF-2α is stabilized in a set of established lymphoma cell lines, underscoring the potential impact of HIF in lymphoma. To further investigate the importance of HIF, we examined TMAs for HIF-1α expression from 153 patients with DLBCL treated with CHOP or rituximab-CHOP (R-CHOP) at the BCCA between 1999–2002. Treatment was before (pre-rituximab) and after (post-rituximab) institution of a policy recommending the combination of rituximab with CHOP for all patients with newly diagnosed advanced-stage DLBCL (March 2001). Tissue sections were stained with monoclonal antibody to HIF-1α and expression (nuclear) was scored by computer (Automated Cellular Imaging System) and validated by pathology review. HIF was dichotomized as either negative (neg; no HIF staining) or positive (pos; score of 1 or greater). Of the 153 patients, 78 were consecutively treated with R-CHOP, while 75 had received CHOP. We found HIF pos expression in 63% (49/78) of patients treated with R-CHOP and 59% (44/75) treated with CHOP (p=NS). Further, based on the Hans algorithm, HIF was expressed in 62% of germinal center (GC) patients and 59% of non-GC patients (P=NS). In the R-CHOP group (see Figure 1A and 1B), the 5-year progression-free survival (PFS) was 45% for HIF neg patients vs 62% for HIF pos (log rank p=0.0187); while the 5-year overall survival (OS) was 48% for HIF neg vs 76% for HIF pos (log rank p=0.025).
In patients treated with CHOP, there was no difference in outcome between HIF pos and HIF neg subsets. In multivariate analysis in the R-CHOP treated group, controlling for the International Prognostic Index (IPI), HIF pos expression remained a significant independent predictor for OS (p=0.03), while the IPI was of borderline significance (p=0.051). Comparison with other biomarkers showed that HIF did not correlate with expression of bcl-2, CD10, MUM-1, or FOXP1; while a high correlation was detected with bcl-6 and HIF (among HIF pos R-CHOP patients, 94% were bcl-6 pos and 6% were bcl-6 neg; p=0.004). We conclude that expression of HIF-1α is an important and heretofore undiscovered independent favorable prognostic factor for PFS and OS in DLBCL patients treated with R-CHOP, but not in patients treated with CHOP. These data suggest there may be an important biological interaction between CD20 monoclonal antibody-based therapy and HIF or downstream genes regulated by HIF. Further study of this observation is warranted.
Figure 1. Survival according to HIF-1α status in patients treated with R-CHOP. Figure 1. Survival according to HIF-1α status in patients treated with R-CHOP.