Phase II Study of Pegvorhyaluronidase Alfa (PEGPH20) and Pembrolizumab for Patients with Hyaluronan-High, Pretreated Metastatic Pancreatic Ductal Adenocarcinoma: PCRT16-001

<b>Background</b>: Stromal hyaluronic acid (HA) poses a physical barrier and protects tumor cells from immune surveillance. Stroma targeting with pegylated human recombinant PH20 hyaluronidase (PEGPH20) demonstrated improved infiltration of cytotoxic T-lymphocytes and delivery of chemotherapy and PD1/PD-L1 antibodies in tumor models. This multicenter phase II study of PEGPH20 plus pembrolizumab evaluated the efficacy, safety and immune and stromal biomarkers in patients with HA-high refractory metastatic pancreatic ductal adenocarcinoma (mPDA). <b>Patients and Methods</b>: Patients were treated with PEGPH20 3 µg/kg IV weekly and pembrolizumab 200 mg IV in 3-week cycles. Tumor and blood samples were collected at baseline and on-study for biomarker analyses. <b>Results:</b> Between May and November 2019, 38 patients were screened and 8 treated, with median age 68 years (range 60-73) and median two (range 1-4) prior therapies. The study was closed to accrual early by pharmaceutical sponsor. Treatment was well tolerated, with expected grade 1/2 musculoskeletal toxicities. Best response was stable disease in 2 of 7 evaluable patients (29%). Median overall and progression-free survival were 7.2 months (95% CI 1.2-11.8) and 1.5 months (95% CI 0.9-4.4), respectively. Prolonged survival (range 10.2-27.6 months) occurred in patients treated with subsequent chemotherapy. Higher baseline tumor T cell receptor (TCR) clonality correlated with longer survival. <b>Conclusions</b>: Pembrolizumab with PEGPH20 was safe but did not have significant efficacy in refractory HA-high metastatic PDA.