Phase II and pharmacodynamic study of autophagy inhibition using hydroxychloroquine in patients with metastatic pancreatic adenocarcinoma

Abstract

Background: Autophagy is a catabolic pathway that permits cells to recycle intracellular macromolecules, and its inhibition reduces pancreatic cancer growth in model systems. We evaluated hydoxychloroquine (HCQ), an inhibitor of autophagy, in patients with pancreatic cancer and analyzed pharmacodynamic markers in treated patients and mice.

Methods: Patients with previously treated metastatic pancreatic cancer were administered HCQ at 400 mg (n = 10) or 600 mg (n = 10) twice daily. The primary endpoint was 2-month progression-free survival (PFS). We analyzed peripheral lymphocytes from treated mice to identify pharmacodynamic markers of autophagy inhibition that were then assessed in peripheral lymphocytes from patients.

Results: Among 20 patients enrolled, 2 (10%) were without progressive disease at 2 months. Median PFS and overall survival were 46.5 and 69.0 days, respectively. Treatment-related grade 3/4 adverse events were lymphopenia (n = 1) and elevated alanine aminotransferase (n = 1). Tolerability and efficacy were similar at the two dose levels. Analysis of treated murine lymphocytes suggested that LC3-II expression by Western blot is a reliable marker for autophagy inhibition. Analysis of LC3-II in patient lymphocytes demonstrated inconsistent autophagy inhibition.

Conclusion: Mouse studies identified LC3-II levels in peripheral lymphocytes as a potential pharmacodynamic marker of autophagy inhibition. In patients with previously treated metastatic pancreatic cancer, HCQ monotherapy achieved inconsistent autophagy inhibition and demonstrated negligible therapeutic efficacy.

©AlphaMed Press; the data published online to support this summary is the property of the authors.

Figures

Figure 1.

Ratio of LC3-II to actin as a biomarker for autophagy inhibition. (A): Autophagy inhibition in mouse lymphocytes. A Western blot probed for LC3, p62, and β-actin in the presence (first three lanes) or absence (second three lanes) of CQ treatment. Each lane comprised pooled lymphocyte samples from two to three individual mice treated with drug or control. (B): A bar graph displays the relative quantity of LC3-II (upper graph) and p62 (lower graph) as a ratio to β-actin as assessed by densitometry. Autophagy inhibition in circulating lymphocytes from patients receiving hydroxychloroquine (HCQ) at either 400 mg b.i.d. (C) or 600 mg b.i.d. (D). Each bar graph reflects results from a single patient prior to treatment (day 0), and then at one time point or more while receiving HCQ. For each patient, a baseline ratio of LC3-II to actin was determined based on assessment by densitometry of Western blot prior to starting (day 0) and then at one time point or more following initiation of HCQ. Graphs in red depict patients with a more than twofold increase in relative LC3-II levels on serial blood draws. Abbreviations: CQ, chloroquine; Ctrl, control.