Abstract 283: PEGylated recombinant hyaluronidase PH20 (PEGPH20) enhances pemetrexed antitumor efficacy in a human nonsquamous NSCLC xenograft model

Introduction: Hyaluronan (HA) is an extracellular matrix glycosaminoglycan that has been shown to accumulate at high levels in several cancers, including non-small cell lung cancer (NSCLC). The accumulation of HA in NSCLC is associated with a more aggressive phenotype and shortened overall survival. In a prevalence analysis using tissue microarrays of archival human specimens (N = 194) stained by affinity histochemistry, we demonstrated that 55% of adenocarcinomas, 74% of squamous cell carcinomas and 83% of large cell carcinomas accumulated HA. The engineered enzyme PEGylated recombinant human hyaluronidase PH20 (PEGPH20) removes HA from the tumor microenvironment. PEGPH20-based therapies are being evaluated in clinical studies of several solid tumors, including NSCLC (NCT02346370, NCT02563548). Herein, we evaluated the hypothesis that PEGPH20 combination therapy could enhance the efficacy of pemetrexed (PEM), a folate antimetabolite approved by FDA as a first-line treatment in combination with cisplatin, against locally advanced and metastatic NSCLC in patients with non-squamous histology. Methods: We evaluated PEGPH20 plus PEM in a NSCLC xenograft model. First, the human NSCLC adenocarinoma cell line A549 was transduced with hyaluronan synthase-3 (HAS3) to generate the A549/HAS3 cell line. Next, A549/HAS3 cells were inoculated adjacent to the tibial periosteum of nude mice and tumor growth was monitored via ultrasonography. When tumors size reached ∼250 mm3, mice were staged into six groups: (1) vehicle; (2) PEGPH20, (3) PEM daily, (4) PEM weekly, (5) PEGPH20+PEM daily or (6) PEGPH20+PEM weekly. Vascular volume, hypoxia and tumor growth inhibition (TGI) were assessed using conventional methods. Affinity histochemical staining for HA was performed on formalin-fixed paraffin-embedded tissue sections after harvest. Results: A549/HAS3 tumors grew faster than parental A549 tumors in vivo. PEGPH20 monotherapy significantly reduced tumoral HA, increased vascular volume and reduced hypoxia in tumors. Further, TGI with PEGPH20+PEM, weekly or daily, was 29.7 or 31.1%, respectively, whereas in either PEGPH20 alone or PEM alone, both were