Breaking the Barrier—PEGylated Recombinant Human Hyaluronidase (PEGPH20)—A New Therapeutic Approach to the Treatment of Pancreatic Ductal Adenocarcinoma

N ew therapeutic approaches are urgently needed to improve survival for patients with metastatic pancreatic ductal adenocarcinoma (PDA). This carcinoma is characterized by a hyaluronan (HA)-rich desmoplastic stroma that raises tumor interstitial fluid pressure (IFP), which in turn compresses the vasculature and impedes access of anti-cancer therapies and immune cells to tumor sites. It is this biophysical barrier that is the target for PEGylated recombinant human hyaluronidase (PEGPH20; pegvorhyaluronidase alfa), which degrades HA polymers to tetraand hexa-saccharides to remodel the tumor stroma. In preclinical models, PEGPH20 reduced IFP, and expanded tumor vasculature to improve perfusion, which increased access for innate immune cells, antibodies and therapeutic agents. The results of a phase Ib study have suggested benefits in overall survival and progression-free survival (PFS) for patients with tumors that accumulate HA (termed HA-High) treated with a combination of gemcitabine and PEGPH20. A phase II study (HALO 109-202) demonstrated that HA could be a potential biomarker for identifying patients who may be most suitable for PEGPH20 treatment. HALO 109-202 showed positive outcomes for PFS especially in HA-High patients treated with PEGPH20 plus nab-paclitaxel and gemcitabine. A randomized, double-blind, phase III study (HALO 109-301) exploring the benefits of PEGPH20 in HA-High patients with PDA is ongoing. Other PEGPH20-based combinations are being investigated in multiple stroma-rich cancers, including lung, gastric, and breast. PEGPH20 is the most advanced therapy targeting the tumor stroma and has the potential to form the therapeutic backbone for the treatment of stroma-rich tumors.