Abstract 2740: PEGylated recombinant hyaluronidase PH20 (pegvorhyaluronidase alfa PEGPH20) converts HA-rich tumors from resistant to sensitive to anti-PD-L1 immunotherapy in murine syngeneic breast cancer models

Abstract

Abstract Hyaluronan (HA) is an extracellular glycosaminoglycan that accumulates in the tumor microenvironment (TME) of many solid tumors. In preclinical studies, enzymatic degradation of TME HA by intravenous PEGylated recombinant human hyaluronidase PH20 (PEGPH20) remodels the TME, reduces tumor interstitial fluid pressure, decompresses tumor blood vessels, and facilitates delivery of chemotherapeutics. PEGPH20-mediated HA degradation increases anti-PD-L1 efficacy in HA-rich EMT-6 tumors and enhances CD8+ T-cell infiltration in tumors. Cancer patients can be resistant to anti-PD-L1; strategies to increase T cell infiltration may lead to anti-PD-L1 effectiveness in nonresponders. We hypothesized that PEGPH20 may convert HA-rich tumors with low T cell infiltration from resistant to sensitive to anti-PD-L1 immunotherapy. 4T1 breast cancer cells transduced with HAS3 to generate HA-rich 4T1/HAS3 cells averaged ~2.9×104 CD8+ T cell/g tumor on day 18 post-tumor inoculation and were resistant to anti-PD-L1 monotherapy. PEGPH20 treatment of 4T1/HAS3 tumors significantly increased CD8+ T cell infiltration to ~7.2×104/g tumor (p=0.0007) and 4T1/HAS3 tumors became sensitive to anti-PD-L1 treatment. PEGPH20 + anti-PD-L1 led to 64.0% tumor growth inhibition (TGI; p<0.0001 vs vehicle + isotype antibody [IgG2b]) vs PEGPH20 alone (10.7% TGI) or anti-PD-L1 alone (-5.1% TGI). PEGPH20 significantly increased infiltration of CD4+ T cells and NK cells, and decreased the percentage of CD11b+GR1+ myeloid derived suppressive cells among CD45+ cells, vs vehicle + IgG2b in 4T1/HAS3 tumors. EMT-6 tumors were sensitive to anti-PD-L1 when starting tumor size was small (~133 mm3) but became resistant with larger starting tumor size (~325 mm3). PEGPH20 + anti-PD-L1 converted larger EMT-6 tumors to sensitive to anti-PD-L1 with 64.9% TGI (p=0.049 vs vehicle + IgG2b), whereas neither PEGPH20 alone nor anti-PD-L1 alone significantly inhibited tumor growth. Small EMT-6 tumors (~136 mm3) were resistant to a lower dose of anti-PD-L1; however, PEGPH20 + low-dose anti-PD-L1 converted EMT-6 tumors from resistant to sensitive to low-dose anti-PD-L1 (65.4% TGI, p<0.0001 vs vehicle + IgG2b). Imaging studies using fluorescence-labeled anti-PD-L1 antibody showed PEGPH20 enhanced the accumulation of anti-PD-L1 in TME. Our data suggest that PEGPH20-mediated HA removal increases infiltration of lymphocytes and immunotherapeutic antibody accumulation in HA-rich tumors. PEGPH20 converts HA-rich tumors from resistant to sensitive to anti-PD-L1. Clinical trials are ongoing to evaluate PEGPH20 + anti-PD-L1 in patients with cholangiocarcinoma/gallbladder cancer (NCT03267940) and gastric cancer (NCT03281369), and to evaluate PEGPH20 + anti-PD-1 in patients with non-small cell lung cancer and gastric cancer (NCT02563548). Citation Format: Renee Clift, Xiaoming Li, Barbara Blouw, Curtis B. Thompson, Yujun Huang. PEGylated recombinant hyaluronidase PH20 (pegvorhyaluronidase alfa PEGPH20) converts HA-rich tumors from resistant to sensitive to anti-PD-L1 immunotherapy in murine syngeneic breast cancer models [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 2740.