CD47-blocking immunotherapies stimulate macrophage-mediated destruction of small-cell lung cancer
Kipp Weiskopf, … , Irving L. Weissman, Julien Sage
Kipp Weiskopf, … , Irving L. Weissman, Julien Sage
Published June 13, 2016
Citation Information: J Clin Invest. 2016;126(7):2610-2620. https://doi.org/10.1172/JCI81603.
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Concise Communication Oncology

CD47-blocking immunotherapies stimulate macrophage-mediated destruction of small-cell lung cancer

Abstract

Small-cell lung cancer (SCLC) is a highly aggressive subtype of lung cancer with limited treatment options. CD47 is a cell-surface molecule that promotes immune evasion by engaging signal-regulatory protein alpha (SIRPα), which serves as an inhibitory receptor on macrophages. Here, we found that CD47 is highly expressed on the surface of human SCLC cells; therefore, we investigated CD47-blocking immunotherapies as a potential approach for SCLC treatment. Disruption of the interaction of CD47 with SIRPα using anti-CD47 antibodies induced macrophage-mediated phagocytosis of human SCLC patient cells in culture. In a murine model, administration of CD47-blocking antibodies or targeted inactivation of the Cd47 gene markedly inhibited SCLC tumor growth. Furthermore, using comprehensive antibody arrays, we identified several possible therapeutic targets on the surface of SCLC cells. Antibodies to these targets, including CD56/neural cell adhesion molecule (NCAM), promoted phagocytosis in human SCLC cell lines that was enhanced when combined with CD47-blocking therapies. In light of recent clinical trials for CD47-blocking therapies in cancer treatment, these findings identify disruption of the CD47/SIRPα axis as a potential immunotherapeutic strategy for SCLC. This approach could enable personalized immunotherapeutic regimens in patients with SCLC and other cancers.

Authors

Kipp Weiskopf, Nadine S. Jahchan, Peter J. Schnorr, Sandra Cristea, Aaron M. Ring, Roy L. Maute, Anne K. Volkmer, Jens-Peter Volkmer, Jie Liu, Jing Shan Lim, Dian Yang, Garrett Seitz, Thuyen Nguyen, Di Wu, Kevin Jude, Heather Guerston, Amira Barkal, Francesca Trapani, Julie George, John T. Poirier, Eric E. Gardner, Linde A. Miles, Elisa de Stanchina, Shane M. Lofgren, Hannes Vogel, Monte M. Winslow, Caroline Dive, Roman K. Thomas, Charles M. Rudin, Matt van de Rijn, Ravindra Majeti, K. Christopher Garcia, Irving L. Weissman, Julien Sage

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Figure 1

CD47 is a therapeutic target for SCLC.

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CD47 is a therapeutic target for SCLC. (A) Histological analysis of macr...
(A) Histological analysis of macrophage infiltration in SCLC patient samples (n = 79). Specimens were stained for the macrophage markers CD68 and CD163. Samples were scored from 1 to 3 (1, low; 2, moderate; 3, intense) based on macrophage infiltration, with representative images of each score depicted (left). One sample exhibited no evidence of macrophage infiltration (not shown). Chart depicts a summary of macrophage infiltration scores as varied by tumor stage (right) (correlation coefficient r = 0.2721; P = 0.0153). Scale bar: 300 μm. (B) CD47 expression on human SCLC cell lines (n = 6) by flow cytometry. Dotted black line, unstained NCI-H82 cells. (C) CD47 expression on SCLC patient sample PDX NJH29 (left) and quantification of CD47 on PDX samples from chemonaive patients (n = 3) and patients with recurrent tumors after chemotherapy (treated, n = 4). (D) Gating strategy used for flow cytometry analysis of phagocytosis assays performed with human macrophages (CD45+) and calcein AM–labeled SCLC cells. Percentages of calcein AM+ macrophages out of total CD45+ macrophage population are indicated. (E) Representative images of cell populations after sorting. The double-positive population contains macrophages with engulfed tumor cells. Scale bar: 20 μm. Experiment performed twice with similar results. (F) Summary of phagocytosis assays using human macrophages and calcein AM–labeled SCLC cell lines (left) or primary NJH29 SCLC cells as analyzed by flow cytometry. SCLC cells were treated with vehicle control (PBS) or anti-CD47 antibodies (Hu5F9-G4). Assays performed with macrophages from independent donors (n = 4) and depicted as the percentages of calcein AM+ macrophages (right) or normalized to the maximal response by each donor (left). Data represent mean ± SD. **P < 0.01; ****P < 0.0001, 2-way ANOVA with Šidák correction (left) or 2-tailed t test (right).