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PDF file, 128K, Depletion of myeloid-derived suppressive cells.

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PDF file, 197K, Antitumor activity of intracranial CNT-CpG.

Purpose: Targeted nanotherapies are being developed to improve tumor drug delivery and enhance therapeutic response. Techniques that can predict response will facilitate clinical translation and may help define optimal treatment strategies. We evaluated the efficacy of diffusion-weighted magnetic resonance imaging to monitor early response to CRLX101 (a cyclodextrin-based polymer particle containing the DNA topoisomerase I inhibitor camptothecin) nanotherapy (formerly IT-101), and explored its potential as a therapeutic response predictor using a mechanistic model of tumor cell proliferation.Experimental Design: Diffusion MRI was serially conducted following CRLX101 administration in a mouse lymphoma model. Apparent diffusion coefficients (ADCs) extracted from the data were used as treatment response biomarkers. Animals treated with irinotecan (CPT-11) and saline were imaged for comparison. ADC data were also input into a mathematical model of tumor growth. Histological analysis using cleaved-caspase 3, terminal deoxynucleotidyl transferase–mediated dUTP nick end labeling, Ki-67, and hematoxylin and eosin (H&E) were conducted on tumor samples for correlation with imaging results.Results: CRLX101-treated tumors at day 2, 4, and 7 posttreatment exhibited changes in mean ADC = 16 ± 9%, 24 ± 10%, 49 ± 17%, and size (TV) = −5 ± 3%, −30 ± 4%, and −45 ± 13%, respectively. Both parameters were statistically greater than controls [p(ADC) ≤ 0.02, and p(TV) ≤ 0.01 at day 4 and 7], and noticeably greater than CPT-11–treated tumors (ADC = 5 ± 5%, 14 ± 7%, and 18 ± 6%; TV = −15 ± 5%, −22 ± 13%, and −26 ± 8%). Model-derived parameters for cell proliferation obtained using ADC data distinguished CRLX101-treated tumors from controls (P = 0.02).Conclusions: Temporal changes in ADC specified early CRLX101 treatment response and could be used to model image-derived cell proliferation rates following treatment. Comparisons of targeted and nontargeted treatments highlight the utility of noninvasive imaging and modeling to evaluate, monitor, and predict responses to targeted nanotherapeutics. Clin Cancer Res; 19(9); 2518–27. ©2013 AACR.

PDF file, 73K, In vitro CNT-CpG activity assay.

Purpose: Recently, we showed that intratumoral delivery of low-dose, immunostimulatory CpG oligodeoxynucleotides conjugated with carbon nanotubes (CNT-CpG) was more effective than free CpG and not only eradicated intracranial (i.c.) gliomas but also induced antitumor immunity that protected mice from subsequent i.c. or systemic tumor rechallenge. Here, we examined whether the same “intracerebral immunotherapy” strategy could be applied to the treatment of metastatic brain tumors.Experimental Design: Mice with both i.c. and s.c. melanomas were injected intratumorally with CNT-CpG into either location. Antitumor responses were assessed by flow cytometry, bioluminescent imaging, and animal survival.Results: When given s.c., CNT-CpG response was mostly local, and it only modestly inhibited the growth of i.c. melanomas. However, i.c. CNT-CpG abrogated the growth of not only brain but also s.c. tumors. Furthermore, compared with s.c. injections, i.c. CNT-CpG elicited a stronger inflammatory response that resulted in more potent antitumor cytotoxicity and improved in vivo trafficking of effector cells into both i.c. and s.c. tumors. To investigate factors that accounted for these observations, CNT-CpG biodistribution and cellular inflammatory responses were examined in both tumor locations. Intracranial melanomas retained the CNT-CpG particles longer and were infiltrated by Toll-like receptor (TLR-9)–positive microglia. In contrast, myeloid-derived suppressive cells were more abundant in s.c. tumors. Although depletion of these cells before s.c. CNT-CpG therapy enhanced its cytotoxic responses, antitumor responses to brain melanomas were unchanged.Conclusions: These findings suggest that intracerebral CNT-CpG immunotherapy is more effective than systemic therapy in generating antitumor responses that target both brain and systemic melanomas. Clin Cancer Res; 18(20); 5628–38. ©2012 AACR.

PDF file - 64K, Boxplots of cellular proliferation rates for different treatment groups calculated by applying ADC data to a logistic model of tumor growth. Boxplots for (A) control, (B) CRLX101 and (C) CPT-11 animals between day 0/2, day 0/4, day 2/4, and day 4/7 are shown.

PDF file - 74K, P-values of histological comparisons of CRLX101 and CPT-11 cohorts with controls on different days. Statistically significant values are highlighted (p < 0.01, *, p < 0.05, �).

PDF file - 112K, Quantitative histological assessment of CRLX101 and CPT-11 response. Tumors treated with CRLX101 (5 mg/kg), CPT-11 (100 mg/kg) or saline were harvested for histology on days 0, 2, 4, and 7. Tumor samples were subsequently sectioned and stained with (A) Cleaved caspase-3 (co-stained with hematoxylin), (B) TUNEL (co-stained with hematoxylin), (C) Ki-67 (co-stained with hematoxylin) and (D) H&E. Three fields of view from each tumor slide were analyzed to obtain measurements of positive cleaved caspase-3 and TUNEL staining, percentage of Ki-67 expression and cellular density (as demonstrated by hematoxylin staining). Statistically significant values, as compared to the control cohort for each time point, are highlighted (p < 0.01, *, p < 0.05, �). Error bars denote standard error.

Supporting Information from Optimizing Radiolabeled Engineered Anti-p185HER2 Antibody Fragments for In vivo Imaging

Supplementary Video 2 from Combining Adoptive Cellular and Immunocytokine Therapies to Improve Treatment of B-Lineage Malignancy

Supplementary Video 1 from Combining Adoptive Cellular and Immunocytokine Therapies to Improve Treatment of B-Lineage Malignancy

Currently, the lineage-specific cell-surface molecules CD19 and CD20 present on many B-cell malignancies are targets for both antibody- and cell-based therapies. Coupling these two treatment modalities is predicted to improve the antitumor effect, particularly for tumors resistant to single-agent biotherapies. This can be shown using an immunocytokine, composed of a CD20-specific monoclonal antibody fused to biologically active interleukin 2 (IL-2), combined with ex vivo expanded human umbilical cord blood–derived CD8+ T cells, that have been genetically modified to be CD19 specific, for adoptive transfer after allogeneic hematopoietic stem-cell transplantation. We show that a benefit of targeted delivery of recombinant IL-2 by the immunocytokine to the CD19+CD20+ tumor microenvironment is improved in vivo persistence of the CD19-specific T cells, and this results in an augmented cell-mediated antitumor effect. Phase I trials are under way using anti-CD20-IL-2 immunocytokine and CD19-specific T cells as monotherapies, and our results warrant clinical trials using combination of these two immunotherapies. [Cancer Res 2007;67(6):2872–80]