Search

Raman spectroscopy provides excellent specificity forin vivopreclinical imaging through a readout of fingerprint-like spectra. To achieve sufficient sensitivity forin vivoRaman imaging, metallic gold nanoparticles larger than 10 nm were employed to amplify Raman signals via surface-enhanced Raman scattering (SERS). However, the inability to excrete such large gold nanoparticles has restricted the translation of Raman imaging. Here we present Raman-active metallic gold supraclusters that are biodegradable and excretable as nanoclusters. Although the small size of the gold nanocluster building blocks compromises the electromagnetic field enhancement effect, the supraclusters exhibit bright and prominent Raman scattering comparable to that of large gold nanoparticle-based SERS nanotags due to high loading of NIR-resonant Raman dyes and much suppressed fluorescence background by metallic supraclusters. The bright Raman scattering of the supraclusters was pH-responsive, and we successfully performedin vivoRaman imaging of acidic tumors in mice. Furthermore, in contrast to large gold nanoparticles that remain in the liver and spleen, the supraclusters dissociated into small nanoclusters, and 73% of the administered dose to mice was excreted over 4 months. The highly excretable Raman supraclusters demonstrated here offer great potential for clinical applications ofin vivoRaman imaging by replacing non-excretable large gold nanoparticles.

This presentation will start with a tribute to Sanjiv Sam Gambhir. Sam is recognized as a founding father of molecular imaging and created the Molecular Imaging Program at Stanford. Molecular imaging is an interdisciplinary biomedical imaging subfield that focuses on mapping biological molecules and processes of clinical interest within living subjects. Sam also had a vision for precision health, asking us to “think about how to either prevent cancer or detect cancer very early when we have the best chance of making a difference.” He was convinced that a revolution in precision health was coming, and may have arrived, and inspired us all with his vision. Our program continues to build upon this vision. Within our molecular imaging program, 34 radiopharmaceutical INDs are in place with human studies underway spanning tumor targeting, immune cell imaging, metabolic imaging, and imaging of gene expression, among other areas. The growth of liquid biopsy techniques in cancer screening opens new opportunities to develop the molecular imaging field to provide the means to map and assess early disease. Concurrently, the field of theragnostics, radio-theragnostics in particular, is rapidly growing. Theragnostics is a unique treatment regimen in that the spatial distribution of the target protein is first imaged in each patient and, when appropriate, the targeted therapeutic isotope is injected and tracked with imaging. The needs of both early detection and theragnostics center around the selection of targets that are present in disease but not found in normal tissue. As with disease detection through blood markers, pan-cancer targets are of particular interest for molecular imaging. 18F-FDG has been widely applied to detect disease and characterize tissue metabolic activity; however, it is limited by lack of cellular specificity. Fibroblast activation protein, extracellular matrix proteins, glycolytic enzymes and immune cell markers are among the many features that can also be mapped with imaging. In particular, imaging of activated fibroblasts and CD8+ T cells are under evaluation as complementary or alternative molecular imaging approaches. Further, the emergence of spatial transcriptomics and highly multiplexed immunohistochemical methods are opening possibilities to identify targets from fine needle aspirates and core biopsies that are obtained under imaging guidance. In order to enhance the utility of imaging with positron emission tomography (PET) and computed tomography (CT), efforts are underway to reduce the radioactivity associated with these imaging studies by extending the field of view of the PET scanner, increasing CT sensitivity and efficiently using the CT x-ray spectrum via photon-counting detectors, or pairing PET with MRI. Finally, multiplexed PET imaging is technically feasible. Together, these developments are advancing molecular imaging for early multi-cancer detection and characterization of disease. Citation Format: Katherine Ferrara. Molecular imaging and multi-cancer detection for precision medicine. [abstract]. In: Proceedings of the AACR Special Conference: Precision Prevention, Early Detection, and Interception of Cancer; 2022 Nov 17-19; Austin, TX. Philadelphia (PA): AACR; Can Prev Res 2023;16(1 Suppl): Abstract nr IA004.

The tumor microenvironment (TME) subtype is a critical factor when combining immunotherapy with tumor debulking strategies such as ultrasound ablation. To understand the effects of the TME subtype, we studied two multi-site murine cancer models, an immune-suppressed KPC (Kras+/LSL-G12D; Trp53+/LSL-R172H; Pdx1-Cre) pancreatic adenocarcinoma (MT4) model and a neu deletion HER2+ (NDL) mammary adenocarcinoma model with a larger naïve lymphocyte population. After profiling the two models with histology and single-cell sequencing, we designed immunotherapy combinations with Magnetic Resonance-guided Focused Ultrasound (MRgFUS) thermal ablation that were specific to each TME subtype. To understand the impact of the molecular and cellular differences upon each model, we characterized the treatment effect with transcriptomic analysis and digital cytometry. We found that combining MRgFUS ablation with immunotherapy reduced tumor growth and extended survival by at least 2-fold in the MT4 pancreatic cancer model. Gene set enrichment analysis (GSEA) of bulk RNA sequencing data indicated that the combination of ablation with immunotherapy preferentially enriched functional annotations for leukocyte migration in the MT4 model and wound healing and inflammatory cytokines in the NDL model (e.g. for IL6: 1.6 fold increase in MT4 vs 10.3 fold in NDL tumors). We then particularly focused on whether dendritic cell (DC) activation and CD4 T cell populations could be enhanced when ablating pancreatic tumors. By CIBERSORTx digital cytometry, aCD40 + aPD-1 combinations increased the presence of activated DCs in MT4 tumors by 2.4-fold. Activated DCs were also increased by CP4 (aCD40 + aPD-1 + CTLA-4) alone 1.7 fold or in combination with ablation in both treated (2.4 fold) and distant (2.2 fold) lesions. Ablation combined with aPD-1 alone did not significantly impact DCs in the MT4 model. In addition, CD4 lymphocytes increased 5 and 8 fold in treated and distant tumors by ablation combined with CP4 in the MT4 model. Taken together, inflammatory cytokines were preferentially elevated by ablation in a dense epithelial breast cancer as compared with a pancreatic tumor model. Further, the results suggest that aCD40 immunotherapy retains efficacy when combined with thermal ablation in pancreatic tumors. This work can inform clinical translation of ablative and immunotherapy combination protocols. Citation Format: James Wang, Brett Z. Fite, Aris Kare, Bo Wu, Marina N. Raie, Spencer Tumbale, Ryan R. Davis, Clifford G. Tepper, Katherine Ferrara. TME subtype impacts response to combined thermal ablation and immunotherapy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 6314.

465 Background: TURBT is the standard surgical procedure for diagnosis, staging, and initial treatment of non-muscle invasive bladder cancer. This study aimed to identify current geographic trends associated with the use and cost of TURBT in Medicare beneficiaries. Methods: The Medicare Limited Data Set 100% sample of outpatient and 5% sample of carrier claims data from Q1 2019 to Q3 2020 was used for analysis. Patients who underwent TURBT were identified using CPT codes (55234, 52235, 52240). An analysis of variance (ANOVA) test was run comparing the difference in average claim payment amount, average beneficiary payment to physician, and average allowed charge amount between each region (West, Midwest, Northeast, and South). If the ANOVA test found a significant difference between regions, a t-test was run for all combinations of regions. Results: In the outpatient setting, we identified a total of 92,938 TURBT procedures between 2019 and Q3 2020, including 23,039 (Midwest), 19,890 (Northeast), 33,379 (South), and 16,630 (West). The average Medicare claim payment amount was $2,755 overall, $2,566 (Midwest), $2,866 (Northeast), $2,497 (South), and $3,092 (West). Beneficiaries paid an average of $605 in the Midwest, $673 in the Northeast, $572 in the South, and $697 in the West. The average total charge was $7,343, $7,189, $8,510, and $10,028 in the Midwest, Northeast, South, and West respectively. In the outpatient setting, there were no statistical differences for any cost related variables between the four regions. In the physician office setting, we identified 8,035 TURBT between 2019 and Q3 2020. There were 1,776, 1,577, 3,153, and 1,529 TURBT procedures in the Midwest, Northeast, South, and West, respectively. The average Medicare claim cost was $383 (Midwest), $372 (Northeast), $423 (South), and $417 (West). The average total allowed charges on the claim was $415 overall, and $392, $404, $430, and $432 in the Midwest, Northeast, South, and West, respectively. There was a significant statistical difference (p = 0.0154) for the average claim payment amount between the South and the Northeast. The two regions differed in average claim payment amount by $51 (95% CI: $15, $87). There was a significant difference in the average allowed charge amount between the South and Midwest (p = 0.019) and the West and Midwest (p = 0.016). Compared to the South, the Midwest had a lower average charge amount by $37 (95% CI: $9, $66). The West had a higher average charge amount than the Midwest by $40 (95% CI: $12, $68). Conclusions: This analysis demonstrated a significant difference in the cost of TURBT between regions in the physician office setting. The South had a significant higher claim payment amount than the Northeast. The allowed charge amount in the physician office setting for the South and the West were significantly higher than the Midwest.

Therapeutic applications of ultrasound have been considered for over 40 years, with the mild hyperthermia and associated increases in perfusion produced by ultrasound harnessed in many of the earliest treatments. More recently, new mechanisms for ultrasound-based or ultrasound-enhanced therapies have been described, and there is now great momentum and enthusiasm for the clinical translation of these techniques. This dedicated issue of Advanced Drug Delivery Reviews, entitled "Ultrasound for Drug and Gene Delivery," addresses the mechanisms by which ultrasound can enhance local drug and gene delivery and the applications that have been demonstrated at this time. In this commentary, the identified mechanisms, delivery vehicles, applications and current bottlenecks for translation of these techniques are summarized.

We sought to use ultrasonography to quantify renal size and echogenicity in a mouse model of polycystic kidney disease. We imaged 36 wild-type (WT) and juvenile cystic kidney (jck) mice by using a standard ultrasound unit and 10-5 MHz linear transducer. Mice were imaged at 3 (6 WT, 7 jck), 6 (7 WT, 5 jck), and 9 (6 WT, 5 jck) wk of age. Kidney length, width, and height were recorded for volume calculation. Sagittal images of both kidneys were recorded for assessment of intensity. Quantitative values were obtained from areas of similar depth and gain settings. Kidney and liver intensities were determined for calculation of their ratio. Representative histologic kidney sections were stained with hematoxylin and eosin and digitized for calculation of cyst number, mean cyst area, and percentage cystic area. We found that renal volume was greater in jck than WT mice at 3 (P0.0001), 6 (P0.0001), and 9 (P0.0001) wk of age. In addition, kidney intensity and kidney:liver ratio were higher in jck than WT mice at 3 (P0.002 for both parameters), 6 (P0.04), and 9 wk (P0.008). Kidneys with smaller mean cyst size and less percentage cystic space had higher intensity values. We therefore conclude that ultrasound measures of renal volume and intensity can noninvasively identify jck-affected mice as early as 3 wk of age. Cortical intensity is greater in jck versus WT mice and appears affected by percentage cyst area and mean cyst size.