Best of AACR Journals

Cancer Research
Research Article
Complex Tumor Genomes Inferred from Single
Circulating Tumor Cells by Array-CGH and
Next-Generation Sequencing
Jochen B. Geigl
Ellen Heitzer, Martina Auer, Christin Gasch, Martin Pichler, Peter Ulz, Eva Maria Hoffmann, Sigurd Lax,
Julie Waldispuehl-Geigl, Oliver Mauermann, Carolin Lackner, Gerald Höfler, Florian Eisner, Heinz Sill,
Hellmut Samonigg, Klaus Pantel, Sabine Riethdorf, Thomas Bauernhofer, Jochen B. Geigl, and Michael R. Speicher
Michael R. Speicher
Abstract
Circulating tumor cells (CTC) released into blood from primary
cancers and metastases reflect the current status of tumor
genotypes, which are prone to changes. Here, we conducted
the first comprehensive genomic profiling of CTCs using array–
comparative genomic hybridization (CGH) and next-generation
sequencing. We used the U.S. Food and Drug Administration–
cleared CellSearch system, which detected CTCs in 21 of 37
patients (range, 1–202/7.5 mL sample) with stage IV colorectal
carcinoma. In total, we were able to isolate 37 intact CTCs from
six patients and identified in those multiple colorectal cancer–
associated copy number changes, many of which were also
present in the respective primary tumor. We then used massive
parallel sequencing of a panel of 68 colorectal cancer–associated
genes to compare the mutation spectrum in the primary tumors,
metastases, and the corresponding CTCs from two of these
patients. Mutations in known driver genes [e.g., adenomatous
polyposis coli (APC), KRAS, or PIK3CA] found in the primary
tumor and metastasis were also detected in corresponding
CTCs. However, we also observed mutations exclusively in
CTCs. To address whether these mutations were derived from
a small subclone in the primary tumor or represented new
variants of metastatic cells, we conducted additional deep
sequencing of the primary tumor and metastasis and applied
a customized statistical algorithm for analysis. We found that
most mutations initially found only in CTCs were also present
at subclonal level in the primary tumors and metastases from
the same patient. This study paves the way to use CTCs as a
liquid biopsy in patients with cancer, providing more effective
options to monitor tumor genomes that are prone to change
during progression, treatment, and relapse. Cancer Res; 73(10);
2965–75. ©2013 AACR.
Cancer Res May 15, 2013 73:2965–75; Published OnlineFirst March
7, 2013; doi: 10.1158/0008-5472.CAN-12-4140
Research Article
Targeting Tumor-Infiltrating Macrophages Decreases
Tumor-Initiating Cells, Relieves Immunosuppression,
and Improves Chemotherapeutic Responses
Jonathan B. Mitchem, Donal J. Brennan, Brett L. Knolhoff, Brian A. Belt, Yu Zhu, Dominic E. Sanford, Larisa Belaygorod,
Danielle Carpenter, Lynne Collins, David Piwnica-Worms, Stephen Hewitt, Girish Mallya Udupi, William M. Gallagher,
Craig Wegner, Brian L. West, Andrea Wang-Gillam, Peter Goedegebuure, David C. Linehan, and David G. DeNardo
David G. DeNardo
Abstract
Tumor-infiltrating immune cells can promote chemoresistance
and metastatic spread in aggressive tumors. Consequently, the
type and quality of immune responses present in the neoplastic
stroma are highly predictive of patient outcome in several cancer
types. In addition to host immune responses, intrinsic tumor cell
activities that mimic stem cell properties have been linked to
chemoresistance, metastatic dissemination, and the induction of
immune suppression. Cancer stem cells are far from a static cell
population; rather, their presence seems to be controlled by highly
dynamic processes that are dependent on cues from the tumor
stroma. However, the impact immune responses have on tumor
stem cell differentiation or expansion is not well understood. In
this study, we show that targeting tumor-infiltrating macrophages
(TAM) and inflammatory monocytes by inhibiting either the
myeloid cell receptors colony-stimulating factor-1 receptor (CSF1R)
or chemokine (C–C motif) receptor 2 (CCR2) decreases the number
of tumor-initiating cells (TIC) in pancreatic tumors. Targeting CCR2
or CSF1R improves chemotherapeutic efficacy, inhibits metastasis,
and increases antitumor T-cell responses. Tumor-educated
macrophages also directly enhanced the tumor-initiating capacity
of pancreatic tumor cells by activating the transcription factor
STAT3, thereby facilitating macrophage-mediated suppression of
CD8 + T lymphocytes. Together, our findings show how targeting
TAMs can effectively overcome therapeutic resistance mediated by
TICs. Cancer Res; 73(3); 1128–41. ©2012 AACR.
Cancer Res February 1, 2013 73:1128–41; Published OnlineFirst
December 5, 2012; doi: 10.1158/0008-5472.CAN-12-2731
The Best of the AACR Journals 15