Date of Award

January 2017

Document Type

Open Access Thesis

Degree Name

Medical Doctor (MD)

Department

Medicine

First Advisor

David L. Rimm

Abstract

Predictive biomarkers for antibodies against programmed death 1 (PD-1) remain a major unmet need in metastatic melanoma. Thus, we evaluated three alternative tissue- and blood based markers biomarkers for response to anti-PD-1 therapy. First, pre-treatment melanoma samples were assayed for expression of: 1) IRF-1, a PD-L1 transcription factor, as a proxy for a tumor’s capacity to express PD-L1, and 2) an immune activation panel consisting of CD3, Ki67, and Granzyme B to distinguish immune-active and immune-quiescent tumors. Additionally, we conducted pilot studies to determine the feasibility of measuring soluble PD-L1 in the plasma of cancer patients.

For tissue-based assays, samples from melanoma patients that received nivolumab, pembrolizumab, or combination ipilimumab/nivolumab at Yale New Haven Hospital from May 2013 to March 2016 were collected. Expression of IRF-1 and PD-L1 in archival pre-treatment formalin-fixed, paraffin-embedded tumor samples were assessed by the AQUA method of quantitative immunofluorescence. Objective radiographic response (ORR) and progression-free survival (PFS) were assessed using modified RECIST v1.1 criteria. For pilot studies of sPD-L1, plasma from 62 patients with non-small cell lung cancer and 10 cancer-free controls were accessed from pre-existing de-identified tissue banks at Yale School of Medicine.

Nuclear IRF-1 expression was higher in patients with partial or complete response (PR/CR) than in patients with stable or progressive disease (SD/PD) (p = 0.044). There was an insignificant trend toward higher PD-L1 expression in patients with PR/CR (p = 0.085). PFS was higher in the IRF-1-high group than the IRF-1-low group (p = 0.017), while PD-L1 expression had no effect on PFS (p = 0.83). In a subset analysis, a strong association between IRF-1 and PFS is seen in patients treated with combination ipilimumab and nivolumab (p = 0.0051). Higher CD3 infiltrates were more likely to be associated with PR/CR (p = 0.0067) and with improved PFS (p = 0.017). Conversely, higher expression of Granzyme B within CD3+ cells was associated with SD/PD (p = 0.023) and a trend toward inferior PFS (p = 0.066). Soluble PD-L1 in human plasma was detected by ELISA, and was elevated in NSCLC cases compared to controls (p < 0.0001).

As a measure of PD-L1 expression capability, IRF-1 expression may be a more valuable predictive biomarker for anti-PD-1 therapy than PD-L1 itself. Additionally, patients with quiescent immune infiltrates may benefit more from anti-PD-1 therapy than those with immune-active tumors. The viability of plasma-based predictive biomarkers for immunotherapies warrants additional investigation.

Comments

This is an Open Access Thesis.

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