Second-line Study of PEGPH20 and Pembro for HA High Metastatic PDAC

Combination strategies geared towards blocking the PD1/PD-L1 inhibitory pathway, such as with pembrolizumab, concurrent with stroma depletion (PEGPH20) may induce synergistic anti-cancer activity and immune responses in pancreatic cancer. Effective harnessing of the immune system and rational combinations with stroma-targeting biological agents (PEGPH20) is a novel field that needs to be explored in pancreatic cancer. This phase II trial will determine the efficacy of pembrolizumab plus PEGPH20 in metastatic pancreatic cancer patients who have HA-high tumor expression. Stroma and immune-related biomarkers will be tested prospectively in blood and tumor biopsies at baseline, after 6 weeks of therapy, and at time of cancer progression. A phase I study with pembrolizumab and PEGPH20 is ongoing in lung and gastric cancer patients (NCT02563548), and demonstrated safety and tolerability of this combination at the doses administered in this study (Halozyme data). Immunotherapies have the potential to induce durable therapeutic responses although this typically occurs in a small fraction of patients. Biomarker-guided patient selection can, in principle, identify those patients most likely to benefit. The investigators hypothesize that stroma remodeling with PEGPH20 will potentiate effector CD8 T cell lymphocyte infiltration and sensitize pancreatic cancer to immune therapy, and that immunologic, and/or genomic biomarkers will identify patient subsets most likely to benefit. As examples, MSI-high status and high tumor mutational burden (hypermutation) have been linked to sensitivity to immune checkpoint inhibitors (Le et al. 2015, Le et al. 2016). Assays may include but are not limited to: Immunohistochemical analysis, profiling of the immune transcriptome, circulating cytokine analyses, flow cytometric analyses of peripheral and intratumoral immune response. This is an open label non-randomized Phase II trial for patients with previously treated metastatic ductal pancreatic adenocarcinoma with HA-high expression, to assess the progression-free survival rate (PFS) of patients treated with this combination therapy. Secondary endpoints will assess safety and tolerability, overall response rate (ORR), disease control rate (DCR= CR+PR+SD), duration of response and stable disease (DOR), and overall survival (OS). There will be an estimated 35 patients enrolled into the study, using 5 centers in the U.S. Overall response rates as well as individual categories of response (CR, PR, SD, and PD) will be determined using RECIST 1.1. Time-to-event endpoints, including PFS and OS will be assessed using the Kaplan-Meier method. Toxicity (adverse events) will be recorded using the NCI CTCAE, version 5.0 (published Nov 2017, Appendix B). All patients will start treatment with PEGPH20 3 microgram/kg IV weekly x 3, and pembrolizumab 200 mg IV every 3 weeks, in 3-week cycles. Patients may remain on treatment with PEGPH20 in combination with pembrolizumab as long as they are receiving clinical benefit, until disease progression per RECIST 1.1 criteria, or until untolerable toxicity develops, whichever comes first. If no disease progression, patients will be allowed to remain on study treatment for up to 24 months. If no disease progression, but with unacceptable toxicity from PEGPH20, patients will be allowed to continue on pembrolizumab alone for up to 24 months if deemed appropriate by the investigator. If pembrolizumab needs to be discontinued for toxicity, patients may continue treatment with PEGPH20 alone. The estimated duration for accrual is anticipated to be 12 months. Patients will be followed up for a minimum of 6 months. The overall study duration is estimated at approximately 18 months.