PIK3CA is mutated in ~15% of colorectal cancers (CRC). PI3K regulates immunity, inhibition potentially enhances anti-tumor immunity. We launched a phase 1/2 trial of copanlisib (PIK3CA inhibitor) and nivolumab (anti-PD-1) in metastatic microsatellite stable CRC (NCT03711058): Cohort A: PIK3CAwt (n = 17) and Cohort B: PIK3CAmut (n = 22). Copanlisib/nivolumab is well tolerated with recommended phase 2 dose of nivolumab 480 mg day 1 and copanlisib 60 mg days 1/8/15 of a 28-day cycle. Primary endpoint of objective response rate at 6 months was not met with Cohort A: 0/17 and Cohort B: 2/22 having 6-month treatment response. Secondary endpoints are median progression-free survival (Cohort A: 1.7 months; Cohort B: 1.6 months), median overall survival (Cohort A: 8.5 months; Cohort B: 6.7 months), duration of response (Cohort A: 13.1 months; Cohort B: 17 months) and 6-month disease control rate (Cohort A: 2/17; Cohort B: 3/22). Secondary endpoints were not statistically different between these cohorts.

Abstract Phosphatidylinositol-4,5-Bisphosphate 3-Kinase Catalytic Subunit Alpha (PIK3CA) is frequently mutated in CRC, leading to constitutive activation and enhanced cellular growth. PI3K also regulates immunity; inhibition of this pathway suppresses Tregs and myeloid derived suppressor cells resulting in enhanced anti-tumor immune responses. Murine experiments combining PD-1 and PI3K inhibition showed an increased CD8+ T cell:Treg ratio and improved survival compared to either alone. We launched a multicenter phase I/II investigation of copanlisib (PI3K inhibitor) and nivolumab (anti-PD-1) in 2 cohorts of patients with metastatic MSS CRC, Cohort 1: PIK3CA mutant (PI3KCAm) and Cohort 2: PIK3CA wild type (PIK3CAwt). From 2/2019 to 4/2022, 39 patients were enrolled: 6 in the phase 1 portion and 33 in phase 2 (22 PIK3CAm/17 PIK3CAwt). All patients had received at least 2 lines of prior therapy. Patient demographics and best treatment responses are in Table 1. There were no dose-limiting toxicities; toxicities were as expected and tolerable, most commonly hypertension in 16 (41%) patients and maculopapular rash in 4 (10%) patients. 3 patients in cohort 1 (14%) had partial responses (PR) and 3 had stable disease (SD): (range 1.7-4.7 mo.). One patient in Cohort 2 (6%) had a PR and 4 had SD: (range 3.8-7.4 mo.). Notably, all 4 responses have lasted more than 2 years. The trial incorporated robust translational correlates for mechanism interrogation with serial biopsies and blood draws. We will report circulating cytokine profiling, mass cytometry on PBMCs, and highly multiplexed immunofluorescence imaging (CyCIF) on paired pre- and on-treatment tissue specimens to i) dissect immune and PI3K pathway changes with treatment ii) correlate these to clinical responses and iii) determine baseline biomarkers of response and mechanism of effect. Overall copanlisib/nivolumab was well tolerated. The PIK3CAm CRC cohort met the primary endpoint for objective response rate but later than 6 months as responses were evolving. Table 1: Demographics and Best Treatment Responses of Patients Treated on NCT03711058: Study of Copanlisib and Nivolumab in MSS Colorectal Cancer Age Sex Race RAS-RAF status Best Response TMB Total (n=39) 58 (40-83) F: 53%(21), M: 47%(18) AA: 15%(6), AS: 8%(3), W: 77%(30) Altered: 67%(26), Wild type: 33%(13) PR: 10%(4), SD: 18%(7), PD: 72%(28) 5 (1-10) PIK3CA mutant (n=22) 57.5 (42-83) F: 73%(16), M: 27%(6) AA:23%(5), AS: 9%(2), W: 68%(15) Altered: 73%(16), Wild type: 27%(6) PR: 14%(3), SD: 14%(3), PD: 73%(16) 5 (1-10) Exon 9 mutation (n=13) 58 (45-83) F: 77%(10), M: 23%(3) AA: 15%(2), AS: 8%(1), W: 77%(10) Altered 85%(11), Wild type: 15%(2) PR: 8%(1), SD: 8%(1), PD: 85%(11) 7.9 (1-18) Exon 20 mutation (n=5) 62 (43-76) F: 80%(4), M: 20%(1) AA: 20%(1), W: 80%(4) Altered: 80%(4), Wild type: 20%(1) PR: 20%(1), SD: 20%(1), PD: 60%(3) 4 (3-8) Other (n=4) 46 (42-54) F: 50%(2), M: 50%(2) AS: 25%(1), AA: 50%(2), W: 25%(1) Altered: 75%(3), Wild type: 25%(1) PR: 25%(1), PD: 75%(3) 5.3 (3-7.6) PIK3CA wild type (n=17) 59 (40-81) F: 29%(5), M: 71%(12) AA: 6%(1), AS: 6%(1), W: 82%(15) Altered: 59%(10), Wild type: 41%(7) PR: 6%(1), SD: 24%(4), PD: 71%(12) 5.5 (1-9) AA: African American, AS: Asian, C: Caucasian, F: Female, M: Male, PD: Progressive disease, PR: Partial Response, SD: Stable disease Citation Format: Eric S. Christenson, Jeremiah A. Wala, Rose Parkinson, Natalie B. Collins, Christopher Jakubowski, Jea-Ren Lin, Hao Wang, Won Jin Ho, Sabrina Chan, Rachel Klein, Yvette Cetasaan, Emma Johnson, Maureen Berg, Jeffrey Meyerhardt, Benjamin Schlechter, Harshabad Singh, Peter K. Sorger, Marios Giannakis, Nilofer Azad. Phase 1/2 trial of copanlisib in combination with nivolumab for microsatellite stable (MSS) colorectal cancer (CRC) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(7_Suppl):Abstract nr CT007.

Abstract The histone variant H3.3 K27M mutation is common in diffuse midline gliomas (DMG) and is associated with poor prognosis. While some insights into K27M epigenetic functions have emerged, much less is known about how K27M impacts chromatin structure and function, and the resulting transcriptomic consequences. Recently, we developed isogenic CRISPR-edited DMG cell lines that are wild-type for histone H3.3 that can be compared to their matched K27M lines. ATAC-seq analysis of the matched sets of isogenic WT and H3.3K27M glioma cells pointed to unique K27M-associated accessible chromatin at regions corresponding to specific neurogenesis, NOTCH, and neuronal development pathways. These domains corresponded to genes that are overexpressed in H3.3K27M compared to our isogenic wild-type cell lines. Uniquely accessible enhancers and super-enhancers corresponding to increased gene expression in H3.3K27M cells were also mapped to genes involved in neurogenesis and NOTCH signaling, suggesting that these pathways are important for tumorigenesis. Motif analysis implicates specific transcription factors as central to the neuro-oncogenic K27M signaling pathway including, in particular, ASCL1 and NEUROD1. CUT&RUN for ASCL1 defined novel target genes in DMG and BioID identified key epigenomic cofactors for ASCL1 including SMARCA4. Large-scale computational analysis of both our and other groups’ data including by chromHMM identified novel functional chromatin domains and potential looping events related to K27M as well. Overall, our findings indicate that H3.3K27M changes specific chromatin functions altering neurodevelopmental gene expression resulting in aberrant activity of an oncogenic epigenomic program. Encouragingly, this program appears at least partially reversible upon editing K27M back to wild-type, pointing to potential translational impact moving forward to targeting this pathway.

Introduction: Cholangiocarcinomas (CCA) are rare, aggressive tumors often diagnosed in advanced stages with limited evidence guiding therapy on progression. Case Report: We report a case of advanced CCA with rapid and aberrant progression, refractory to multiple lines of therapy, that resulted in severe hepatic dysfunction secondary to tumor burden with a BRAF V600E mutation and high tumor proportion score (TPS) of 99%. To our knowledge, this is the first reported use of BRAF/MEK inhibition to target BRAF V600E in a patient with severe hepatic dysfunction leading to rapid normalization of the patient’s liver dysfunction within days. No adverse events were recorded during either initial titration or maintenance periods. Programmed death-1 (PD-1) inhibitor was added to BRAF/MEK inhibition, and the patient continues to have clinical therapeutic response. Conclusion: This case highlights the use of BRAF/MEK inhibition in CCA with BRAF V600E mutations in hepatic dysfunction due to tumor burden and the role of combining immune checkpoint inhibitors.

A neoadjuvant immunotherapy platform clinical trial allows for rapid evaluation of treatment-related changes in tumors and identifying targets to optimize treatment responses. We enrolled patients with resectable pancreatic adenocarcinoma into such a platform trial (NCT02451982) to receive pancreatic cancer GVAX vaccine with low-dose cyclophosphamide alone (Arm A; n = 16), with anti-PD-1 antibody nivolumab (Arm B; n = 14), and with both nivolumab and anti-CD137 agonist antibody urelumab (Arm C; n = 10), respectively. The primary endpoint for Arms A/B - treatment-related change in IL17A expression in vaccine-induced lymphoid aggregates - was previously published. Here, we report the primary endpoint for Arms B/C: treatment-related change in intratumoral CD8+ CD137+ cells and the secondary outcomes including safety, disease-free and overall survivals for all Arms. Treatment with GVAX+nivolumab+urelumab meets the primary endpoint by significantly increasing intratumoral CD8+ CD137+ cells ( p = 0.003) compared to GVAX+Nivolumab. All treatments are well-tolerated. Median disease-free and overall survivals, respectively, are 13.90/14.98/33.51 and 23.59/27.01/35.55 months for Arms A/B/C. GVAX+nivolumab+urelumab demonstrates numerically-improved disease-free survival (HR = 0.55, p = 0.242; HR = 0.51, p = 0.173) and overall survival (HR = 0.59, p = 0.377; HR = 0.53, p = 0.279) compared to GVAX and GVAX+nivolumab, respectively, although not statistically significant due to small sample size. Therefore, neoadjuvant and adjuvant GVAX with PD-1 blockade and CD137 agonist antibody therapy is safe, increases intratumoral activated, cytotoxic T cells, and demonstrates a potentially promising efficacy signal in resectable pancreatic adenocarcinoma that warrants further study.

Recent research on genomic profiling of pancreatic ductal adenocarcinoma (PDAC) has identified many potentially actionable alterations. However, the feasibility of using genomic profiling to guide routine clinical decision making for PDAC patients remains unclear. We retrospectively reviewed PDAC patients between October 2013 and December 2017, who underwent treatment at the Johns Hopkins Hospital and had clinical tumor next-generation sequencing (NGS) through commercial resources. Ninety-two patients with 93 tumors tested were included. Forty-eight (52%) patients had potentially curative surgeries. The median time from the tissue available to the NGS testing ordered was 229 days (interquartile range 62–415). A total of three (3%) patients had matched targeted therapies based on genomic profiling results. Genomic profiling guided personalized treatment for PDAC patients is feasible, but the percentage of patients who receive targeted therapy is low. The main challenges are ordering NGS testing early in the clinical course of the disease and the limited evidence of using a targeted approach in these patients. A real-time department level genomic testing ordering system in combination with an evidence-based flagging system for potentially actionable alterations could help address these shortcomings.

Background Data analysis of specimens from prior clinical trials identified the immune co-simulatory molecule CD137 within the tumor microenvironment(TME) of pancreatic ductal adenocarcinoma(PDAC) that remain to be activated following vaccine induced T cell and PD-1 inhibitory treatments. The requirement of CD137 was subsequently supported by preclinical studies. Therefore, we conducted a clinical trial of combining anti-CD137 agonist antibody urelumab, anti-PD-1 antagonist antibody nivolumab and a GM-CSF-secreting allogeneic tumor cell vaccine(GVAX) as neoadjuvant and adjuvant therapy for resectable PDAC. Methods Patients of >=18 years old with radiographic evidence of resectable PDACs were eligible for Arm C of this trial(NCT02451982) with an accrual goal of 10 evaluable subjects. The primary objective was to evaluate changes in numbers of tumor infiltrating CD137+CD8+ T cells. Secondary objectives were safety, overall survival, disease free survival, and other immune parameters. Patients who underwent R0/R1 resection were considered evaluable. All subjects received 480mg nivolumab and 8 mg urelumab both intravenously one day prior to receiving GVAX intradermally and two weeks before surgical resection (figure 1). After surgery, eligible patients continued to receive 5 combination immunotherapy cycles in addition to standard of care chemotherapy. Treatment-related toxicity and perioperative complications are monitored. Results Between February 2019 and August 2020, we completed planned enrollment and treated 10 evaluable patients, who underwent R0 surgical resection of their PDACs. Nausea is the most common adverse event attributed to urelumab (table 1). Other adverse events and perioperative complication were observed in a type, frequency and degree similar to other treatment arms. After repeated dosing, 1 patient demonstrated grade 1 arthritis; 1 patient demonstrated self-limited, transient grade 2 elevated LFTs; 1 patient developed grade 3 rashes, which responded quickly to oral steroid and did not recur after re-dosing. Interestingly, two out of 10 resected patients demonstrated CAP grade 2 pathologic responses in the resected PDACs after a single neoadjuvant treatment; this was not observed with other treatment cohorts(GVAX alone or GVAX+nivolumab) in this neoadjuvant platform trial. Nine out of 10 resected patients remain disease free after a median follow up of 12 months. Immunology endpoints are being analyzed by multiplex immunohistochemistry, DNA sequencing for neoantigen loads, and RNA/TCR sequencing. Conclusions Previous observations of liver toxicity with urelumab or other T cells agonists and severe immune-related adverse events were not observed in this trial, suggesting urelumab(8 mg) is safe as neoadjuvant/adjuvant therapy in this resectable PDAC patient population. Immune and clinical efficacy of anti-CD137 agonist-based combinations warrant further investigation. Acknowledgements This is an investigator initiated clinical trial and supported by the funding from the Rare Disease Program at Bristol-Myers Squibb. Trial Registration NCT02451982 Ethics Approval The study was approved by the Johns Hopkins Medical Institution Institutional Review Board, approved number IRB00050517

Pediatric high-grade gliomas often contain mutations in the H3F3A gene encoding the histone variant H3.3 and more rarely in canonical histone H3 family genes, a feature distinguishing them from adult gliomas. To define specific functionally significant changes in epigenomic states driven by mutant H3.3, we have utilized CRISPR-Cas9 to introduce specific H3.3 mutations (K27M, G34R) into formerly H3.3 wildtype (WT) brain and glioma cells, while in parallel also precisely reverting the pre-existing K27M and G34R mutations in patient-derived glioma cells to WT. In each case, gene editing was conducted on endogenous H3F3A alleles. Analyses of this overall panel of H3.3 gene-edited cells indicate that CRISPR-introduced K27M or G34R mutations within formerly H3.3 WT cells leads to increased gliomatypic signatures: elevated expression of specific oncogenes as well as neurogenesis and Notch signaling pathway genes, and perturbation of specific histone post-translational marks. Conversely, gene editing-based reversion of histone mutations to WT in primary glioma cells partially reverses glioma-associated phenotypes. Gene editing of K27M also yields coherent phenotype changes in xenograft assays. K27M and G34R mutations appear to function via both shared and unique epigenomic mechanisms. Targeting the mutant H3.3 effector pathways identified by our analyses in our full panel of cells with specific inhibitory drugs plus or minus irradiation defines differential, largely opposite responses of the parental and gene-edited cells. These defined pathways may serve as entry points for development of novel therapies specific for H3.3-mutant pediatric glioma. Overall, this system of gene editing gain and loss of mutant H3.3 provides new insights into oncohistone mechanisms and therapeutic strategies.

Background: Cancer-related gene mutations (CGMs), microsatellite instability (MSI), and tumor mutation burden (TMB) have been identified as potential targets for drugs and immunotherapeutics, providing an avenue for individual patient clinical decision-making. Data on CGMs, MSI, and TMB is limited.

Nanoparticles functionalized with chemotherapeutic drugs and MRI contrast agents can serve dual therapeutic and diagnostic applications. Nano-ablation (NA) employs reversible electroporation to temporarily increase cell membrane permeability, offering interventional oncologists a method to enhance drug delivery to tumors. However, it remains unknown if MRI can be combined with NA to predict intratumoral uptake of superparamagnetic iron oxide nanoparticles (SPIOs) injected intravenously. We aimed to test the hypothesis that T2*-w MRI can be used to quantitatively predict intratumoral uptake of SPIOs. Using the N1S1 model of hepatoma, we induced 11 liver tumors in Sprague-Dawley rats. T2*-w MRI was performed using a Bruker 7T ClinScan to determine baseline tumor T2* signal intensity. Two minutes after SPIO injection into the femoral vein, NA was applied to the liver tumor at 1300 V/cm (8 pulses, 100 μs pulse duration) using bipolar electrodes. Animals were euthanized 10 minutes after NA and MRI determined post-procedural tumor T2* signal intensity. We measured the iron concentration of the harvested tissue from treated subjects as a proxy for SPIO uptake using inductively-coupled plasma mass spectroscopy (ICP-MS). Mean tumor iron concentration was correlated with the mean change in tumor T2* (measured in ms) using linear regression, with p<0.05 considered significant. Change in T2*-w MRI signal intensity significantly correlated with tumor SPIO uptake after NA (p=0.014, r=0.71). On average, for each unit of T2* signal intensity change (one millisecond) there was 7.33 μg of iron uptake per mg of tumor tissue. Intratumoral uptake of SPIOs after NA can be successfully quantified with 7T MRI and this uptake correlates with gold standard pathology. Thus, MRI may be used as a non-invasive method to measure the dose of therapeutic nanoparticles taken up by target liver tumors. Before clinical translation, future studies should attempt to replicate these findings using a larger animal model of liver cancer at clinically relevant 1.5T or 3T MRI field strengths.

Rationale and Objectives: Electropermeabilization involves the application of electrical pulses to increase cell membrane permeability. The purpose of our study was to demonstrate the potential to use electroporation-mediated transcatheter arterial chemoembolization (E-TACE) approaches to increase liver tumor drug uptake while using magnetic resonance imaging (MRI) for intraprocedural optimization of these procedures. Methods: Fourteen VX2 tumors were grown in the left hepatic lobes of 8 rabbits. Two tumors were grown in each of 6 rabbits (1 tumor serving as E-TACE-treated tumor and the other as nonelectroporated control), and solitary larger tumors were grown in 2 rabbits (half of the tumor treated with E-TACE, remaining half serving as control). Each rabbit was selectively catheterized under digital subtraction angiography guidance. Baseline MRI was performed to generate tumor contrast enhancement curves following catheter-directed infusion of gadopentetate dimeglumine to estimate the proper time delay between subsequent bolus infusion of cisplatin and application of electrical pulses (electrodes were used to deliver 8, 100-μs, 1300-V pulses at the selected delay interval postinfusion). Three hours after E-TACE, rabbits were euthanized, and tumors were sectioned for inductively coupled plasma mass spectroscopy measurements of platinum concentration (serving as reference standard of cisplatin uptake levels). Results: Inductively coupled plasma mass spectroscopy results demonstrated significantly increased cisplatin uptake in E-TACE-treated tumor tissues, increases of 6.0 ± 3.3-fold compared with transcatheter infusion alone (P = 0.017). Conclusions: Our findings suggest that our E-TACE approach may significantly increase liver tumor drug uptake after targeted transcatheter infusion. MRI measurements permitted intraprocedural guidance during these catheter-directed E-TACE procedures.

There is a critical unmet need to monitor intratumoral drug uptake non-invasively. Superparamagnetic iron oxide nanoparticles (SPIOs) are agents with dual diagnostic and therapeutic properties that may meet this need. However, systemic (IV) administration results in unfavorable biodistribution with minimal tumor delivery. To overcome this limitation we propose nano-embolization (NE) as the image-guided delivery of SPIOs and embolic agents directly into the blood supply of tumors. It remains unknown if MRI can quantify the amount of NPs delivered to tumors during NE. Using VX2 liver tumors, we tested the hypotheses that a) NE increases uptake of therapeutic SPIOs over IV administration and b) 7T MRI can quantify intratumoral drug delivery. We induced VX2 liver tumors in 20 rabbits, evenly dividing them into NE and control (IV) groups. Both groups received doxorubicin-loaded therapeutic SPIOs at 0.56 mg/kg body weight. For the NE group, SPIOs and ethiodol were delivered into the hepatic artery under fluoroscopy. T2*-weighted gradient echo imaging (Bruker 7T ClinScan MRI) was performed on both groups pre and post-treatment to quantify SPIO delivery and uptake using T2*W mapping. After necropsy, we used ICP-MS as the gold standard to measure SPIO concentrations in normal liver and tumor pathological specimens. We compared SPIO uptake between the groups using ANOVA with post-hoc Tukey analysis, with p<0.05 considered significant. NE significantly increased tumor SPIO uptake 240% over IV delivery alone (340 vs. 140 μg Fe/mg, p<0.05). This correlated with T2*W MRI, which showed a significant T2 signal drop in NE tumors over controls (ΔT2: 47.4 ms vs. 18.9 ms, p<0.05). Furthermore, NE resulted in 75% less off target delivery to healthy liver tissue than IV delivery (p<0.05). NE improves tumor uptake of therapeutic SPIOs over conventional IV administration, with significantly less off-target delivery. 7T MRI can also quantify SPIO uptake non-invasively. To determine the optimal dose of therapeutic nanoparticles to inject, future studies should correlate SPIO delivery with tumor response.

Electropermeabilization involves application of electrical pulses to increase cell membrane permeability; electrochemotherapy (ECT) takes advantage of this phenomenon to increase tumor uptake of chemotherapeutic drugs. The purpose of this study was to demonstrate that MRI-guided ECT permits superior cisplatin uptake within targeted HCC compared to conventional systemic chemotherapy in a rodent HCC model. Two N1-S1 hepatomas were grown in six SD rats. Hepatomas grown in the left medial lobe were treated with MRI-guided ECT, while the hepatoma in the right lobe was not electroporated (serving as internal control). A pre-treatment dynamic contrast enhanced MRI (DCE-MRI) was performed with an injection of Gd-DTPA. A contrast enhancement curve was generated to estimate the time delay between bolus infusion and the period of maximum tumor uptake (used for planning purposes to optimize delay interval, Td, between later cisplatin infusion and application of electrical pulses). For ECT treated tumors, bi-polar electrodes (1cm spacing) were inserted straddling the targeted tumor and 8 100μs 1300V pulses were applied Td sec after IV cisplatin infusion. Next, an immediate post-treatment DCE-MRI was performed to monitor the reduction in tumor perfusion due to ECT vascular lock effects. Animals were euthanized 2 hours after treatment; both hepatoma and normal liver tissues were harvested and sectioned; ICP-MS was used for cisplatin concentration measurements to compare ECT to control tumors (paired t-test, p<0.05 considered significant). Post-ECT DCE-MRI demonstrated reductions to perfusion in electroporated tumors compared to the non-electroporated control tumors in each rat. ICP-MS analysis of platinum concentrations showed significant increases in cisplatin uptake in the ECT treated tumors compared to non-electroporated controls (60% increase, p=0.010 for paired comparisons). Our findings suggest that MRI-guided ECT permits superior chemotherapeutic drug uptake within targeted HCC compared to conventional chemotherapy in the N1-S1 model. MRI guidance should permit patient-specific adjustments to ECT timing parameters for optimal drug delivery to targeted hepatic tumors.

Superparamagnetic Iron Oxide nanoparticles (SPIOs) are an emerging class of agents with diagnostic and therapeutic properties. SPIOs injected systemically (IV) are sequestered by the reticuloendothelial system, with limited tumor uptake. Electroporation (EP) can modulate the influx of therapeutics into cells through the rapid, reversible induction of transmembrane pores. We propose electro-nanotherapy (electro-NT) as the EP of tissues following nanoparticle delivery as a method to increase drug uptake. The purpose of this study was to demonstrate the benefits of this combined locoregional approach in the N1S1 hepatoma model. We hypothesized that electro-NT increases uptake of therapeutic SPIOs over IV injection and that SPIO uptake can be detected with high-resolution 7T MRI. We grew N1S1 tumors in 20 Sprague-Dawley rats, which were evenly divided into electro-NT and control groups. Both groups received doxorubicin functionalized SPIOs, serving as dual imaging and therapeutic agents, at 0.56 mg/kg body weight IV. For the electro-NT group, following SPIO delivery, EP was applied directly to tumors at 500-V/cm field strength (8 pulses, 100-μs pulse duration). T2*-weighted gradient echo imaging (Bruker 7T ClinScan MRI) was performed on both groups pre and post-treatment to detect SPIO delivery and uptake using T2*W mapping. After euthanasia, tumors were harvested for evaluation by ICP-MS for iron concentration. SPIO uptake between the groups were compared with using ANOVA with post-hoc Tukey analysis, with p<0.05 considered significant. Electro-NT significantly increased tumor SPIO uptake over IV delivery alone. Tumors that received electro-NT had a 6.3 fold increase in SPIOs over controls (165 vs. 26.1 μg Fe/mg tissue, p<0.05). This correlated with T2*W MRI, which showed a significant T2 signal drop in electro-NT tumors over controls (T2: 33.5 ms vs. 103.4 ms, p<0.05). Electro-NT considerably improves tumor uptake of therapeutic SPIO over conventional IV administration. 7T MRI is capable of monitoring this SPIO uptake non-invasively. The next experimental steps should determine the efficacy of this new locoregional drug therapy.

PURPOSE:To investigate the contribution of proton density (PD) in T(2) -STIR based edema imaging in the setting of acute myocardial infarction (AMI). MATERIALS AND METHODS:Canines (n = 5), subjected to full occlusion of the left anterior descending artery for 3 hours, underwent serial magnetic resonance imaging (MRI) studies 2 hours postreperfusion (day 0) and on day 2. During each study, T(1) and T(2) maps, STIR (TE = 7.1 msec and 64 msec) and late gadolinium enhancement (LGE) images were acquired. Using T(1) and T(2) maps, relaxation and PD contributions to myocardial edema contrast (EC) in STIR images at both TEs were calculated. RESULTS:Edematous territories showed significant increase in PD (20.3 ± 14.3%, P < 0.05) relative to healthy territories. The contributions of T(1) changes and T(2) or PD changes toward EC were in opposite directions. One-tailed t-test confirmed that the mean T(2) and PD-based EC at both TEs were greater than zero. EC from STIR images at TE = 7.1 msec was dominated by PD than T(2) effects (94.3 ± 11.3% vs. 17.6 ± 2.5%, P < 0.05), while at TE = 64 msec, T(2) effects were significantly greater than PD effects (90.8 ± 20.3% vs. 12.5 ± 11.9%, P < 0.05). The contribution from PD in standard STIR acquisitions (TE = 64 msec) was significantly higher than 0 (P < 0.05). CONCLUSION:In addition to T(2) -weighting, edema detection in the setting of AMI with T(2) -weighted STIR imaging has a substantial contribution from PD changes, likely stemming from increased free-water content within the affected tissue. This suggests that imaging approaches that take advantage of both PD as well as T(2) effects may provide the optimal sensitivity for detecting myocardial edema.

Electropermeabilization involves the application of electrical pulses to increase cell membrane permeability; electrochemotherapy (ECT) takes advantage of this phenomenon to increase tumor uptake of drugs. The purpose of this study in the rabbit VX2 model was to demonstrate that MRI-monitored electroporation-mediated TACE (E-TACE) can increase selective liver tumor drug uptake compared conventional transcatheter infusion methods alone. Two VX2 liver tumors were grown in six rabbits (both implanted in the left medial lobe). Each rabbit was catheterized under DSA guidance with catheter placed in the left hepatic artery. Baseline TRIP-MRI was performed to generate tumor enhancement curves with an IA injection of Gd-DTPA. These contrast enhancement curves were generated to estimate time delay between IA bolus infusion and the period of maximum tumor uptake (for planning purposes to optimize delay interval, Td, between later IA Cisplatin infusion and application of electrical pulses). For E-TACE treated tumors (one tumor in each rabbit) electrodes were inserted straddling the targeted tumor and 8 100μs 1300V pulses applied at the selected delay interval Td after the Cisplatin infusion through the catheter. Next, a post TRIP-MRI scan was performed to assess tumor perfusion alterations and treatment related tumor signal intensity changes. After allowing 3 hours for Cisplatin wash out, rabbits were euthanized and tumor sectioned for ICP-MS measurement of intra-tumoral platinum concentrations. ICP-MS results demonstrated significantly increased Cisplatin uptake in E-TACE treated tumors, roughly 5-fold increase compared to transcatheter infusion alone in four rabbits (n=4/6). T2W-TSE images showed significant intra-tumoral T2 decreases in these four rabbits (likely due to high concentrations of Gd-DTPA) compared to the other two that showed no signal changes but had no differences in Cisplatin uptake. Our findings suggest that E-TACE may be effective for increasing tumor uptake of chemotherapeutic agents and that intra-procedural MRI should permit immediate confirmation of targeted drug delivery based upon signal changes only present in sufficiently treated tissues.