Abstract 5165: Cancer associated macrophage-like cells as a blood-based biomarker for the screening of solid tumors
Authors: Adams Daniel , Alpaugh Katherine , Cristofanilli Massimo , Martin Stuart , Chumsri Saranya , Bergen Raymond C. , Tsai Susan , Edelman Martin , Zhu Peixuan , Li Shuhong , Makarova Olga V. , Amstutz Platte T. , Tang Cha-Mei , Marks Jeffrey R. 
Published: August 2015

Background:

Blood-based biopsies can be used as a non-invasive method to recover both Circulating Tumor Cells (CTCs) and Circulating Cancer Associated Macrophage-Like cells (CAMLs) from the blood of cancer patients. CAMLs are a newly-defined circulating immune cell type, described as a subtype of circulating stromal cells, known to engulf tumor cells/debris. CAMLs are identified by their large size, 30-300 microns, and aberrant nuclear structure. We studied the peripheral blood of cancer patients to ascertain the prevalence, specificity and sensitivity of CAMLs in relation to their disease status at presentation, including a variety of benign and malignant diseases. We supply evidence that this previously unidentified circulating cell can be used as a screening tool to detect solid tumors in numerous malignancy subtypes in all disease stages.

Methods:

CellSieveTM microfilters were used to isolate CAMLs from 7.5 mL of whole peripheral blood. The pore size of CellSieveTM is 7 microns, capable of isolating both CTCs and CAMLs based on size. Collected cells were fixed, permeabilized, and stained with DAPI and antibodies against cytokeratin 8, 18 and 19, CD14, and CD45. CAMLs were defined as enlarged, multinuclear cells with diffuse cytoplasmic cytokeratin staining, and/or CD14+, and/or CD45+. CTCs were defined as filamentous cytokeratin cells that are CD45-.

Study 1: Blinded peripheral blood samples from 61 cancer patients were tested, including Stage I-IV breast, pancreatic, lung and prostate cancers, and newly diagnosed, untreated patients. Non-blinded blood samples from 30 healthy volunteers served as controls.

Study 2: Double blinded peripheral blood samples from 20 patients with abnormal mammogram results were drawn at time of tissue biopsy and screened. After analysis, unblinding showed a distribution of malignant breast disease (n = 10), benign (n = 8), or atypical hyperplasia (AH) (n = 2).

Results:

Study 1: CAMLs were found in 94% patients with Stage III/IV cancers, 87% with Stage I/II cancers, and 89% of all patients, regardless of cancer type. Specifically, CAMLs were found in 77% of prostate, 100% of pancreatic, 80% of lung, and 100% of breast patient samples. CAMLs were not found in healthy control samples (sensitivity: 84-96%, Specificity: 100%, PPV: 100%, NPV: 88-97%).

Study 2: CAMLs were found in 8 patients with malignant disease, 2 with benign disease, and 2 with AH (sensitivity: 80%, Specificity: 75%, PPV: 80%, NPV: 75%)

Conclusions:

We present evidence that CAMLs can be used as a non-invasive blood based biopsy, to detect the anatomical presence of solid malignancies and potentially pre-malignant lesions. The presence of CAMLs in newly diagnosed patient samples suggests their use as a blood biomarker for early stage cancer screening in a broad population. Preliminary data from a double blind breast cancer study suggests that CAMLs may differentiate between benign and malignant breast diseases.

Citation Format: Daniel Adams, Katherine Alpaugh, Massimo Cristofanilli, Stuart Martin, Saranya Chumsri, Raymond C. Bergen, Susan Tsai, Martin Edelman, Peixuan Zhu, Shuhong Li, Olga V. Makarova, Platte T. Amstutz, Cha-Mei Tang, Jeffrey R. Marks. Cancer associated macrophage-like cells as a blood-based biomarker for the screening of solid tumors. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 5165. doi:10.1158/1538-7445.AM2015-5165