Viable Tumor Tissue Research Articles

Ex vivo assessment of cellular mass response for personalized therapy selection of hyperthermic intraperitoneal chemotherapy (HIPEC) agents.

3132 Background: Despite progress in the development of HIPEC protocols for the treatment of peritoneal carcinomatosis, agent selection remains largely empiric with few biomarkers for guiding treatment. Ex vivo assessment of drug response using single-cell mass measurements offers a promising option for therapy selection. Previously, we have shown that mass response testing (MRT) is a malignancy- and drug-agnostic means of assessing drug response (1) and can predict a patient’s clinical response to therapy in a range of solid and hematological malignancies (2). Methods: Tissue specimens were collected from patients with peritoneal carcinomatosis as part of an ancillary study for a HIPEC clinical trial (NCT04847063) to explore the feasibility of performing MRT with these specimen types. Briefly, after overnight shipment of viable tumor tissue, tumor cells were isolated and treated with various therapies ex vivo. Single-cell mass distributions of vehicle and drug-treated populations were compared to determine the functional activity of each agent. Results: MRT was attempted for 60 patients with metastatic disease, 10 of whom had peritoneal carcinomatosis and ultimately received HIPEC. The HIPEC cases included histologies such as peritoneal mesothelioma (n=4), colorectal cancer (n=3), ovarian cancer (n=2), and small bowel adenocarcinoma (n=1). In total, 8 out of 10 peritoneal specimens had a sufficiently high tumor cell count, viability, and purity to perform MRT. These specimens displayed clear and statistically distinguishable mass response patterns of response and non-response to several different agents commonly used for HIPEC treatment such as cisplatin, oxaliplatin, doxorubicin, and mitomycin C. Study design:These feasibility results serve as the foundational data for launching a single-site phase II interventional study at the NCI’s Center for Cancer Research. The study will evaluate the potential benefit of personalized treatment regimens determined by MRT for patients with peritoneal carcinomatosis, particularly mesothelioma, a context where therapeutic options have relative equipoise in clinical efficacy. Tumor biopsies will be obtained via laparoscopy prior to HIPEC and submitted to a CLIA-certified lab for MRT to assess the responses of various clinically acceptable agents. The HIPEC regimen will be selected based on these MRT results returned within two days of sample collection. Enrolled patients will then undergo cytoreduction and HIPEC, and progression-free and overall survival will be monitored. As a single-arm, non-randomized trial, patient responses will be compared with a matched synthetic control to assess the impact of MRT on efficacy of HIPEC regimens. Conclusions: MRT is feasible for peritoneal carcinomatosis tissues, with future studies focusing on its role in guiding HIPEC treatment. 1. Nat Comm Bio,2022. 2. JCO PO, 2024. Clinical trial information: NCT04847063 .

Abstract 7550: KB-0742, an oral highly selective CDK9 inhibitor, demonstrates preclinical activity in transcription factor fusion driven adenoid cystic carcinoma patient-derived models

Abstract Adenoid Cystic Carcinoma (ACC) is an aggressive rare type of cancer of the secretory glands with no approved targeted therapy and high unmet clinical need. Deregulated transcription driven by MYB-NFIB or MYBL1-NFIB transcription factor (TF) fusions are a hallmark of ACC pathogenesis. More aggressive disease and resistance to therapy has been associated with co-mutation in NOTCH. Although direct targeting of oncogenic TF fusions has remained challenging, targeting of their activity via transcriptional cofactors has emerged as an attractive and clinically actionable strategy. Cyclin-dependent kinase 9 (CDK9) is a key potentiator of TF activity via its ability to act both as an upstream regulator of TF expression and a downstream cofactor. KB-0742 is a potent, selective, and orally bioavailable inhibitor of CDK9 with a long plasma half-life. KB-0742 is being studied in an ongoing Phase 1/2 study (NCT04718675) in advanced solid tumors including ACC. KB-0742 has demonstrated on-mechanism, single agent anti-tumor activity and a manageable safety profile in heavily pre-treated patients (0-11 prior lines of therapy) with transcriptionally addicted solid tumors. Here we present the preclinical rationale for targeting of oncogenic fusion TF activity in ACC. XenoSTART Patient-Derived Xenograft (XPDX) models were established from viable human tumor tissue for in vivo and ex vivo testing. Cell viability was assessed by CellTiter GLO reagent and phase imaging. Changes in MYB-fusion transcripts were assessed by RNA-Seq. Tumor Fragments (~70 mg) from ACCx5M1, ACCx6, ACCx9, ACCx11 models were implanted into athymic nude mice. Animals were treated with either vehicle (normal saline) or 60 mg/kg KB-0742 on a Q3D/week until tumors reached 2500 mm3 or up to 60 days post start of treatment. In a retrospective analysis using real world data, ACC has a low incidence of genomic instability and high rates of MYB fusions detectable by RNA-seq, making immunotherapy challenging but creating an opportunity for targeting MYB transcription. In primary MYB-fusion positive and NOTCH co-mutated patient-derived spheroid models, KB-0742 treatment induced strong antiproliferative activity and cytotoxicity. Importantly, KB-0742 demonstrated stronger cytotoxic effects when compared to historical control agents. In XPDXs, CDK9 inhibition with KB-0742 resulted in antiproliferative activity and stronger tumor growth inhibition in MYB-fusion positive and NOTCH co-mutated tumor models compared to MYB-fusion positive only models.These data demonstrate KB-0742 is effective in preclinical models of ACC suggesting KB-0742 may be a promising therapeutic option for ACC patients. KB-0742 is currently being evaluated in a phase 1/2 dose-escalation and cohort expansion trial in patients with ACC and other transcriptionally addicted tumors (NCT04718675). Citation Format: Michael R. McKeown, Luis A. Carvajal, Tressa R. Hood, Nicole S. Burr, Jeffrey Kaufman, Adam Boynton, Kameron Mori, Tessa DesRochers, Michael Wick, Charles Y. Lin, Jorge F. DiMartino. KB-0742, an oral highly selective CDK9 inhibitor, demonstrates preclinical activity in transcription factor fusion driven adenoid cystic carcinoma patient-derived models [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 7550.

Advances in MRI-Based Assessment of Rectal Cancer Post-Neoadjuvant Therapy: A Comprehensive Review.

Rectal cancer presents significant diagnostic and therapeutic challenges, with neoadjuvant therapy playing a pivotal role in improving resectability and patient outcomes. MRI serves as a critical tool in assessing treatment response. However, differentiating viable tumor tissue from therapy-induced changes on MRI remains a complex task. In this comprehensive review, we explore treatment options for rectal cancer based on resectability status, focusing on the role of MRI in guiding therapeutic decisions. We delve into the nuances of MRI-based evaluation of treatment response following neoadjuvant therapy, paying particular attention to emerging techniques like radiomics. Drawing from our insights based on the literature, we provide essential recommendations for post-neoadjuvant therapy management of rectal cancer, all within the context of MRI-based findings.

The use of weakly supervised machine learning for necrosis assessment in patients with osteosarcoma: A pilot study.

Percent necrosis (PN) following chemotherapy is a prognostic factor for survival in osteosarcoma. Pathologists estimate PN by calculating tumor viability over an average of whole-slide images (WSIs). This non-standardized, labor-intensive process requires specialized training and has high interobserver variability. Therefore, we aimed to develop a machine-learning model capable of calculating PN in osteosarcoma with similar accuracy to that of a musculoskeletal pathologist. In this proof-of-concept study, we retrospectively obtained sixWSIs from twopatients with conventional osteosarcomas. A weakly supervised learning model was trained by using coarse and incomplete annotations of viable tumor, necrotic tumor, and nontumor tissue in WSIs. Weakly supervised learning refers to processes capable of creating predictive models on the basis of partially and imprecisely annotated data. Once "trained," the model segmented areas of tissue and determined PN of the same sixWSIs. To assess model fidelity, the pathologist also estimated PN of each WSI, and we compared the estimates using Pearson's correlation and mean absolute error (MAE). MAEwas 15% over the sixsamples, and 6.4% when an outlier was removed, for which the model inaccurately labeled cartilaginous tissue. The model and pathologist estimates were strongly, positively correlated (r = 0.85). Thus, we created and trained a weakly supervised machine learning model to segment viable tumor, necrotic tumor, and nontumor and to calculate PN with accuracy similar to that of a musculoskeletal pathologist. We expect improvement can be achieved by annotating cartilaginous and other mesenchymal tissue for better representation of the histological heterogeneity in osteosarcoma.

P15.14.A DIFFERENTIATE TREATMENT EFFECTS FROM DISEASE PROGRESSION IN TREATED BRAIN TUMOR: PROMISING RESULTS USING DELAYED CONTRAST MRI

Abstract BACKGROUND Treatment effects are reported in about 30% of treated glioma and brain metastases (BMs) characterized by increasing volume of contrast enhancing regions on MRI, similarly to tumor progression. Data interpretation are often difficult. The most methodology used to distinguish this 2 conditions is perfusion MRI; treatment effects are characterized by a decreased relative cerebral blood volume (rCBV) while persistent or progressive tumors by high rCBV. Limits of perfusion MRI are represented by overlap between two conditions, low spatial resolution, and presence of susceptibility artifacts. To overcome this crucial issue, encouraging results have been obtained using delayed contrast MRI that through contrast clearance analysis (CCA) allows to calculate high resolution maps called “treatment response assessment maps” (TRAMs). We prospectively evaluated patients with doubtful framework between treatment effects (TE) and tumor progression (TP) aiming to assess the ability of CCA in differentiate this two conditions in a cohort of treated brain tumor patients. MATERIAL AND METHODS Maps (TRAMS) were calculated through contrast clearance analysis (CCA) by subtracting ceT1MRI images acquired 5 minutes after contrast injection from images acquired at least 60-105 minutes after. Diagnosis of persistent tumors or disease progression was based on presence of contrast clearance (CC) region in blue, and treatment effects on contrast accumulation (CA) region in red. Data of CCA were compared to perfusion MRI. All images were uploaded, co-registered and elaborate into the image workstation of Brainlab. Whole tumor and enhancing tumor volumes were segmented and perfusion measures in area of signal alteration. TRAMs were generated and at last the calculation of effective volume of viable tumor tissue (CC region) and treatment-induced tissue changes within each lesion (CA region) have been calculated. RESULTS From February 2021 and November 2022, 62 patient (96 delayed-contrast-MRI) with doubtful framework between TE and TP underwent CCA and perfusion-MRI. Twenty-five treated for newly diagnosed glioma, 13 for recurrence, and 37 for BMs. Significantly increased rCBV value in CC regions compared to CA was observed (p=0.01). Patients with TP showed significantly greater CC that subjects with stable disease/partial response 33% vs 78% (p=0.01). TRAMs metric were in agreement with perfusion results. Greater accuracy of TRAMs compared to perfusion-MRI in discriminate TE from TP 81% vs 69% has been observed. CONCLUSION In our experience CCA tool compared to perfusion MRI had a greater accuracy in discriminating true tumor progression from treatment induced tissue changes, and can be of improvement in patient management.

Establishment of patient-derived tumor organoids to functionally inform treatment decisions in metastatic colorectal cancer

Metastatic colorectal cancer (mCRC) patients tend to have modest benefits from molecularly driven therapeutics. Patient-derived tumor organoids (PDTOs) represent an unmatched model to elucidate tumor resistance to therapy, due to their high capacity to resemble tumor characteristics. We used viable tumor tissue from two cohorts of patients with mCRC, naïve or refractory to treatment, respectively, for generating PDTOs. The derived models were subjected to a 6-day drug screening assay (DSA) with a comprehensive pipeline of chemotherapy and targeted drugs against almost all the actionable mCRC molecular drivers. For the second cohort DSA data were matched with those from PDTO genotyping. A total of 40 PDTOs included in the two cohorts were derived from mCRC primary tumors or metastases. The first cohort included 31 PDTOs derived from patients treated in front line. For this cohort, DSA results were matched with patient responses. Moreover, RAS/BRAF mutational status was matched with DSA cetuximab response. Ten out of 12 (83.3%) RAS wild-type PDTOs responded to cetuximab, while all the mutant PDTOs, 8 out of 8 (100%), were resistant. For the second cohort (chemorefractory patients), we used part of tumor tissue for genotyping. Four out of nine DSA/genotyping data resulted applicable in the clinic. Two RAS-mutant mCRC patients have been treated with FOLFOX-bevacizumab and mitomycin-capecitabine in third line, respectively, based on DSA results, obtaining disease control. One patient was treated with nivolumab-second mitochondrial-derived activator of caspases mimetic (phase I trial) due to high tumor mutational burden at genotyping, experiencing stable disease. In one case, the presence of BRCA2 mutation correlated with DSA sensitivity to olaparib; however, the patient could not receive the therapy. Using CRC as a model, we have designed and validated a clinically applicable methodology to potentially inform clinical decisions with functional data. Undoubtedly, further larger analyses are needed to improve methodology success rates and propose suitable treatment strategies for mCRC patients.

Breast cancer patient-derived explant cultures recapitulate in vivo drug responses.

Assessment of drug sensitivity in tumor tissue ex vivo may significantly contribute to functional diagnostics to guide personalized treatment of cancer. Tumor organoid- and explant-cultures have become attractive tools towards this goal, although culturing conditions for breast cancer (BC) tissue have been among the most challenging to develop. Validation of possibilities to detect concordant responses in individual tumors and their respective cultures ex vivo is still needed. Here we employed BC patient-derived xenografts (PDXs) with distinct drug sensitivity, to evaluate different conditions for tissue dissociation, culturing and monitoring of treatment efficacy ex vivo, aiming to recapitulate the in vivo drug responses. The common challenge of discriminating between tumor and normal cells in the cultured tissue was also addressed. Following conventional enzymatic dissociation of BC tissue, the tumor cells stayed within the non-disrupted tissue fragments, while the single cells represented mostly normal host cells. By culturing such fragments as explants, viable tumor tissue could be maintained and treated ex vivo, providing representative indications on efficacy of the tested treatment. Thus, drug sensitivity profiles, including acquired chemoresistance seen in the PDXs, were recapitulated in the respective explants. To detect the concordant responses, however, the effect monitoring had to be harmonized with the characteristics of the cultured tissue. In conclusion, we present the feasibility of BC explants ex vivo to capture differences in drug sensitivity of individual tumors. The established protocols will aid in setting up an analogous platform for BC patient biopsies with the aim to facilitate functional precision medicine.

IMMULAB: A phase II trial of immunotherapy with pembrolizumab in combination with local ablation for patients with early-stage hepatocellular carcinoma (HCC).

555 Background: Percutaneous ablation of neoplastic tissue by radiofrequency ablation (RFA), microwave ablation (MWA) or brachytherapy is considered a potentially curative treatment for early HCC, but recurrence rates are high. Local ablative therapies release immunogenic stimuli that can trigger an anti-tumoral immune response, which is, however, dampened by counter-regulatory mechanisms mediated through immune checkpoints, such as CTLA-4 and PD-1. Combining local therapies with immunotherapies may shift the balance to a more robust immunostimulatory response. We therefore hypothesized that peri-interventional treatment with pembrolizumab may synergize with and improve outcome of local ablative therapy. Methods: This single arm phase II trial investigates peri-interventional treatment with pembrolizumab combined with RFA/MWA or brachytherapy, or - as recommended for tumors larger than 3 cm – combined with TACE and RFA/MWA or brachytherapy in early-stage HCC with maintained liver function (Child Pugh A) who did not receive prior local or systemic therapy. Pembrolizumab (200mg, q3w) was administered intravenously for 2 cycles, followed by radiologic imaging and local therapy. Pembrolizumab was continued for up to 12 months. The primary efficacy endpoint was defined as overall response rate (ORR, RECIST 1.1) after 2 cycles of pembrolizumab and before local therapy while secondary endpoints are time to recurrence (TTR, defined as the length of time after performance of local ablation resulting in confirmed absence of viable tumor tissue until documented tumor recurrence), recurrence free survival and overall survival (OS) along with safety and tolerability. Results: 30 patients (pts, ECOG 0 or 1) were enrolled in 9 centers in Germany, with a median age of 70 years and a predominance of male pts (73.3%). All pts received at least 1 dose of study treatment and the median number of cycles was 13. ORR was 13.3%, with 6.7% complete responses (CR) and 6.7% partial responses (PR) after two cycles of pembrolizumab and before local ablation. Subsequent local ablation was performed in 25/30 pts. With ongoing follow-up median of 14 months (Sep 2022), provisional median overall survival time (mOS) was not reached and provisional median time to recurrence (TTR) was 17.41 months. No new safety signs were observed. Conclusions: The study did not meet its primary endpoint. The hypothesized ORR of 30% before local therapy was not reached. However, there is evidence for the efficacy of peri-interventional treatment with pembrolizumab combined with local ablative therapy without new safety signals. Our findings support further evaluation of this combination treatment in early-stage HCC. Clinical trial information: NCT03753659 .

SLC-0111, an inhibitor of carbonic anhydrase IX, attenuates hepatoblastoma cell viability and migration.

In response to hypoxia, tumor cells undergo transcriptional reprogramming including upregulation of carbonic anhydrase (CA) IX, a metalloenzyme that maintains acid-base balance. CAIX overexpression has been shown to correlate with poor prognosis in various cancers, but the role of this CA isoform in hepatoblastoma (HB) has not been examined. We surveyed the expression of CAIX in HB specimens and assessed the impact of SLC-0111, a CAIX inhibitor, on cultured HB cells in normoxic and hypoxic conditions. CAIX immunoreactivity was detected in 15 out of 21 archival pathology HB specimens. The CAIX-positive cells clustered in the middle of viable tumor tissue or next to necrotic areas. Tissue expression of CAIX mRNA was associated with metastasis and poor clinical outcome of HB. Hypoxia induced a striking upregulation of CAIX mRNA and protein in three HB cell models: the immortalized human HB cell line HUH6 and patient xenograft-derived lines HB-295 and HB-303. Administration of SLC-0111 abrogated the hypoxia-induced upregulation of CAIX and decreased HB cell viability, both in monolayer and spheroid cultures. In addition, SLC-0111 reduced HB cell motility in a wound healing assay. Transcriptomic changes triggered by SLC-0111 administration differed under normoxic vs. hypoxic conditions, although SLC-0111 elicited upregulation of several tumor suppressor genes under both conditions. Hypoxia induces CAIX expression in HB cells, and the CAIX inhibitor SLC-0111 has in vitro activity against these malignant cells.

Evaluation of functional and metabolic tumor volume using voxel-wise analysis in childhood rhabdomyosarcoma

BackgroundCross-sectional imaging-based morphological characteristics of pediatric rhabdomyosarcoma have failed to predict outcomes.ObjectiveTo evaluate the feasibility and possible value of generating tumor sub-volumes using voxel-wise analysis of metabolic and functional data from positron emission tomography/magnetic resonance imaging (PET/MR) or PET/computed tomography (CT) and MRI in rhabdomyosarcoma.Materials and methodsThirty-four examinations in 17 patients who received PET/MRI or PET/CT plus MRI were analyzed. The volume of interest included total tumor volume before and after therapy. Apparent diffusion coefficients (ADC) and standard uptake values (SUV) were determined voxel-wise. Voxels were assigned to three different groups based on ADC and SUV: “viable tumor tissue,” “intermediate tissue” or “possible necrosis.” In a second approach, data were grouped into three clusters using the Gaussian mixture model. The ratio of these clusters to total tumor volume and changes due to chemotherapy were correlated with clinical and histopathological data.ResultsAfter chemotherapy, the proportion of voxels in the different groups changed significantly. A significant reduction of the proportion of voxels assigned to cluster 1 was found, from a mean of 36.4% to 2.5% (P < 0.001). There was a significant increase in the proportion of voxels in cluster 3 following chemotherapy from 24.8% to 81.6% (P = 0.02). The proportion of voxels in cluster 2 differed depending on the presence or absence of tumor recurrence, falling from 48% to 10% post-chemotherapy in the group with no tumor recurrence (P < 0.05) and from 29% to 23% (P > 0.05) in the group with tumor recurrence.ConclusionVoxel-wise evaluation of multimodal data in rhabdomyosarcoma is feasible. Our initial results suggest that the different distribution of sub-volumes before and after therapy may have prognostic significance.

CD8 Presence and Dynamics in Glofitamab-Treated Patients with Relapsed/Refractory B-Cell Non-Hodgkin Lymphoma Using the CD8-Specific PET Tracer 89Zr-Crefmirlimab Berdoxam

Background: Glofitamab, a CD20xCD3 T-cell-engaging bispecific monoclonal antibody with a novel 2:1 (CD20:CD3) configuration, redirects T cells to eliminate normal and malignant B cells. In ongoing Phase I/II trials, glofitamab has shown high response rates and durable complete responses in patients with relapsed/refractory (R/R) B-cell lymphomas (Hutchings et al. 2021, J Clin Oncol), including diffuse large B-cell lymphoma (DLBCL; Dickinson et al. ASCO 2022). In this imaging study (NCT03533283), the glofitamab-mediated effects on the distribution of CD8-expressing cells, such as cytotoxic T cells, in patients with R/R B-cell non-Hodgkin lymphoma (NHL) were captured with the novel 89Zr-radiolabeled anti-CD8 humanized minibody crefmirlimab berdoxam (CD8 tracer) for positron emission tomography (PET). Methods: Patients received obinutuzumab (1000 mg) once 7 days before the 1st glofitamab dose; glofitamab was then given as step-up doses on Day 1 (2.5 mg) and Day 8 (10 mg). The baseline infusion of the CD8 tracer was administered prior to obinutuzumab and the on-treatment infusion of the CD8 tracer was performed 48 h (±24 h) after the 1st or 2nd glofitamab dose. The tracer was infused at a fixed dose of 37 MBq (1.5 mg protein); PET/CT scans were performed 24 h post infusion. The primary endpoint was quantification of changes of CD8 tracer uptake (SUVmax) in tumor lesions before and after glofitamab treatment. Paired biopsies for CD8 immunohistochemistry (IHC) and serum pharmacokinetic samples were taken at baseline and on-treatment. Results: To date, 9 evaluable patients with a median of 2 prior treatment lines (range: 1-6) with B-cell NHL (follicular lymphoma (FL), n=5; transformed FL, n=1; DLBCL, n=3) were enrolled. CD8 tracer infusions were well tolerated with no reported tracer-related adverse events. No difference in serum clearance of the CD8 tracer was observed between baseline and on-treatment infusions. Tracer uptake was detected in CD8 rich tissues (e.g. spleen, bone marrow, lymph nodes) and clearance organs (liver, kidney, intestine). Three patients with DLBCL received on-treatment CD8-PET/CT scans after the 2nd glofitamab dose. 11 analyzed DLBCL lesions showed variable CD8 tracer uptake at baseline between SUVmax 2.6-38.27. Following treatment with glofitamab, the signal in 64% of the analyzed lesions was increased 1.2-3.3-fold while the signal in 18% of the lesions was stable and 18% showed a decreased signal compared to baseline. The distribution of the CD8 tracer in individual lesions was highly heterogeneous with areas of low and higher uptake (Fig. 1A). The CD8 IHC of paired biopsy samples taken after PET scans in 1 patient with DLBCL showed good correspondence between PET and IHC signal. The on-treatment biopsy contained quantifiable T cell amounts without detection of viable tumor tissue, suggesting a fast onset of glofitamab activity prior to the selected imaging/biopsy timepoint. 6 patients with FL were analyzed. In 87% of the analyzed 39 FL lesions, a high and heterogenous CD8-tracer uptake between SUVmax 5.3-29.2 was observed at baseline. After one dose of 2.5 mg glofitamab, 36% of the analyzed lesions showed a stable or ≤1.3-fold increase of CD8-tracer uptake. In 64% of the analyzed lesions a ≤2.1-fold decrease of CD8-tracer uptake was observed (Fig.1B). After the 2nd glofitamab dose, CD8-PET-scans of patients with FL revealed that in 86% of the analyzed lesions CD8 tracer uptake decreased 1.2-11.9-fold compared with baseline scans, accompanied by shrinkage of lesion size as detected on low dose CT. Conclusions: Changes in the uptake of the CD8 tracer were observed early after treatment with glofitamab. Preliminary results suggest indication-specific differences in T-cell dynamics after two treatment interventions with glofitamab. In DLBCL, the CD8 tracer confirmed recruitment of T cells to the majority of tumor lesions after two glofitamab treatments. In FL, the preliminary CD8-tracer results suggest that the intra tumoral T cells exhibit their antitumoral effects immediately after glofitamab administration and thus faster compared to the glofitamab-mediated effects in DLBCL. In addition these data indicate that the optimal imaging time point is after the 1st glofitamab dose. 89Zr-crefmirlimab berdoxam is a promising innovative tool to assess the presence and dynamic change of CD8 T cells after treatment with novel immunotherapies for hematological malignancies. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

P05.02.A 18F-FACBC PET/MRI in diagnostic assessment of gliomas

Abstract Background and Theory MRI and histopathological tissue sampling are routinely done as part of the diagnostic work-up of patients with glioma. MRI provides anatomical images with high resolution and excellent soft-tissue contrast. But this modality has limitations in identifying tumor grade, true tumor extension and differentiate viable tumor tissue from treatment induced changes. PET can provide quantitative information of cellular activity and metabolism, and may therefore have additional value compared to MRI alone. Objective The aim of this study was to find the sensitivity of [18F]FACBC PET in gliomas, and evaluate if PET imaging with this tracer can improve differentiation between low-and high-grade gliomas. Methods Patients with suspicion of primary (n=19) or recurrent gliomas (n=8) were recruited to this study from St. Olavs hospital, Trondheim University Hospital, Trondheim, and from the University Hospital of North Norway, Tromsø. PET acquisitions (30-45 min post injection) using the amino acid radiotracer [18F]FACBC (3 MBq/kg) were performed simultaneously to MRI acquisitions (T1 with and without contrast, FLAIR, and UTE for attenuation correction. The sensitivity of [18F]FACBC PET in glioma detection was assessed using histopathology as reference. Tumor-to-background ratios (TBRs) were compared to tumor subtype and grade to assess the diagnostic value of this tracer for glioma diagnostics. Results Histopathology revealed 2 WHO grade 1 gliomas (pilocytic astrocytoma n=1, pilocytic astrocytoma/ganglioglioma n=1), 7 WHO grade 2 gliomas(astrocytoma n=4, oligodendroglioma n=3), 7 WHO grade 3 gliomas(astrocytoma n=5, oligodendroglioma n=2) and 12 WHO grade 4 tumors(astrocytoma n=1, glioblastoma n=11). [18F]FACBC PET provided a sensitivity of 74.1% in the detection of gliomas. PET uptake was observed in all grade 4 tumors, 5/7 grade 3 tumors, 2/7 grade 2 tumors, and all grade 1 tumors. TBRpeak was high with a median value of 9.4 (range: 2.1-34.9) in PET positive tumors. Only tumors with a TBRpeak &amp;gt; 2.0 were detected with [18F]FACBC PET. TBRpeak was highest for grade 1 gliomas with a median value of 20.6, and increased significantly from grade 2 to grade 4 tumors with median values of 1.7 (grade 2), 6.2 (grade 3) and 12.4 (grade 4) (Kruskal-Wallis, p=0.001). Conclusion [18F]FACBC PET demonstrated high uptake in the majority of gliomas, and there was a clear tendency to higher uptake in the higher grade tumors. [18F]FACBC PET may be useful in the differentiation between glioms grades and subtypes. A future study using the same patient data will be performed to evaluate the assessment of [18F]FACBC PET in neurosurgical treatment planning. Image-localized biopsies from different regions of each tumor will be correlated to fused PET/MRI images to evaluate if [18F]FACBC PET can be used to guide surgical resection and to improve accuracy in histopathological tissue sampling.

Abstract 2071: Probody-interferon-alpha 2b combines antitumor activity with improved tolerability

Abstract Type I interferons can exert direct antitumor effects, modulate tumor stroma, and induce de novo antitumor immune responses. They have demonstrated combination activity with PD-(L)1 blockade to potentially expand the benefit to patients with unresponsive tumors. Despite its potential, the toxicity of interferon alpha has limited its clinical use. Here we applied CytomX proprietary Probody® Therapeutics (Pb-Tx) technology to create a conditionally active IFN-α2b (Pb-IFN-α2b) with minimal activity in its prodrug form. The prodrug is activated in the tumor microenvironment (TME), leading to preferential activity in the TME but not in healthy tissues. Pb-IFN-α2b demonstrated an enhanced tolerability profile compared to standard IFN therapy without compromising its antitumor effects. The Pb-Tx platform technology attenuates activity of a molecule by blocking its active regions through affinity or steric interference. Such blockade, termed masking, is reversed upon proteolytic cleavage of a substrate-containing linker between the molecule and the mask by tumor associated proteases. Pb-IFN molecules were engineered with a dual masking approach combining the effects of steric inhibition by Fc fusion and affinity interference by a peptide mask. Pb-IFN-α2b demonstrated significant reduction (1000-fold or more) of its specific activity in vitro, including antiproliferative effects and immune cell activation. Treatment with tumor-associated proteases or exposure to viable tumor tissues fully restored its activity. Activated but not masked Pb-IFN-α2b induced a gene expression profile consistent with interferon signaling in primary human immune cells. In vitro studies with dissociated human tumors demonstrated the ability of Pb-IFN to activate tumor immune infiltrate, which could be further enhanced by concomitant PD-L1 blockade. Antitumor activity of the Pb-IFN-α2b in xenograft studies is equal to or greater than Peg-IFN-α2b. Pb-IFN-α2b demonstrated significant antitumor activity in syngeneic mouse tumor models without evidence of toxicity. Consistent with in vitro observations, this anti-tumor activity was further enhanced by PD-(L)1 blockade. Toxicology studies performed in hamsters demonstrated enhanced tolerability of the molecule compared to its unmasked control. Pb-IFN-α2b did not cause hematological changes or body weight loss associated with unmasked interferon. In cynomolgus monkey Pb-IFN-α2b demonstrated linear pharmacokinetics, extended half-life, and was well tolerated at doses up to 15 mg/kg. Pb-IFN-α2b shows improved tolerability and antitumor activity in preclinical studies compared to traditional IFN treatment. These data support Probody cytokine therapeutics as a promising addition to current immunotherapy regimens, potentially expanding their benefits to patients with typically unresponsive tumors. Citation Format: Alexey Berezhnoy, Hsin Wang, Nicole Lapuyade, Na Cai, Carol LePage, Michael B. Winter, Ivan Ye, Hong Lu, Michael Krimm, Ken Wong, Robert T. Dunn, Leila Boustany, Madan Paidhungat, Marcia Belvin, Erwan Le Scolan, Dylan Daniel. Probody-interferon-alpha 2b combines antitumor activity with improved tolerability [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 2071.

The Incidence and Its Associated Factors Relevant to Brain Radionecrosis That Requires Intervention Following Single or Fractionated Stereotactic Radiosurgery Using Vero4DRT for Brain Metastases.

Purpose: Several factors, including the surrounding brain volume receiving specific doses, have hitherto been reported to correlate with brain radionecrosis (BR) after single or fractionated stereotactic radiosurgery (sSRS or fSRS) for brain metastases (BMs); however, those, especially for fSRS, have not yet been fully elucidated. Furthermore, the clinical outcome data of patients with BM treated with SRS using Vero4DRT are extremely limited. Therefore, this study aimed to demonstrate the incidence of BR requiring intervention (BRRI) and its highly correlated factors.Materials and Methods: Patients with BMs treated with sSRS or fSRS using Vero4DRT at Toyohashi Municipal Hospital between July 2017 and June 2021 were retrospectively reviewed, of whom patients were available for at least 20 weeks of magnetic resonance imaging follow-up from SRS were included, and analyzed. The prescribed dose fractionation schemes to the planning target volume (PTV) boundary included 24 Gy (sSRS), 35 Gy (5 fractions [fr]), 42 Gy (10 fr), and 30 Gy (3 fr), according to the tumor volume and location. The volume of the surrounding normal brain receiving 84 Gy (V84 Gy, biologically effective dose [BED2] based on a linear-quadratic model with an alpha/beta ratio of 2, single-dose equivalent [SDE] to 12 Gy), V112 Gy (BED2, SDE to 14 Gy) for all lesions, and all irradiated volume, including gross tumor volume (GTV) receiving 81.6 Gy (81.6 Gy vol., BED2) for fSRS were calculated, for which cerebrospinal fluid and bone volumes were cautiously excluded. The diagnosis of tumor progression or BR dominance was based on serial T1/T2 matching.Results: Sixty patients with 120 lesions (65 treated with sSRS and 55 treated with fSRS) were included in the final analysis, with a median follow-up period of 65 weeks. The local control rate at one year was 87.5%. The cumulative incidence of BRRI within two years was 11.5%. The risk of symptomatic BR was significantly higher for V84 Gy >10 cc (p <0.001) and V112 Gy >5 cc (p = 0.021). In the fSRS group, the cumulative incidence of Grade 3 BR and those requiring resection was significantly higher for 81.6 Gy vol. >14 cc (p = 0.003 and p = 0.004, respectively). The coexistence of viable tumor tissue and BR could not be ruled out for enlarging lesions after the nadir response, especially for fSRS, due to a lower BED10 to GTV margin (<80 Gy, BED10).Conclusions: Stereotactic irradiation with Vero4DRT provided efficacy and safety comparable to previous linear accelerator series, and most of the dose-volume thresholds for BRRI presented in this study were notably lower than those reported in previous studies. This study suggests that the indication of single and up to 5 frSRS should be limited to far smaller tumors than previously acknowledged to ensure long-term safety and efficacy.

5-Aminolevulinic Acid-Induced Protoporphyrin IX Fluorescence Imaging for Tumor Detection: Recent Advances and Challenges

5-Aminolevulinic acid (5-ALA) is a natural amino acid and a precursor of heme and chlorophyll. Exogenously administered 5-ALA is metabolized into protoporphyrin IX (PpIX). PpIX accumulates in cancer cells because of the low activity of ferrochelatase, an enzyme that metabolizes PpIX to heme. High expression of 5-ALA influx transporters, such as peptide transporters 1/2, in cancer cells also enhances PpIX production. Because PpIX radiates red fluorescence when excited with blue/violet light, 5-ALA has been used for the visualization of various tumors. 5-ALA photodynamic diagnosis (PDD) has been shown to improve the tumor removal rate in high-grade gliomas and non-muscular invasive bladder cancers. However, 5-ALA PDD remains a challenge as a diagnostic method because tissue autofluorescence interferes with PpIX signals in cases where tumors emit only weak signals, and non-tumorous lesions, such as inflammatory sites, tend to emit PpIX fluorescence. Here, we review the current outline of 5-ALA PDD and strategies for improving its diagnostic applicability for tumor detection, focusing on optical techniques and 5-ALA metabolic pathways in both viable and necrotic tumor tissues.

Complications Risk Assessment and Imaging Findings of Thermal Ablation Treatment in Liver Cancers: What the Radiologist Should Expect.

One of the major fields of application of ablation treatment is liver tumors. With respect to HCC, ablation treatments are considered as upfront treatments in patients with early-stage disease, while in colorectal liver metastases (CLM), they can be employed as an upfront treatment or in association with surgical resection. The main prognostic feature of ablation is the tumor size, since the goal of the treatment is the necrosis of all viable tumor tissue with an adequate tumor-free margin. Radiofrequency ablation (RFA) and microwave ablation (MWA) are the most employed ablation techniques. Ablation therapies in HCC and liver metastases have presented a challenge to radiologists, who need to assess response to determine complication-related treatment. Complications, defined as any unexpected variation from a procedural course, and adverse events, defined as any actual or potential injury related to the treatment, could occur either during the procedure or afterwards. To date, RFA and MWA have shown no statistically significant differences in mortality rates or major or minor complications. To reduce the rate of major complications, patient selection and risk assessment are essential. To determine the right cost-benefit ratio for the ablation method to be used, it is necessary to identify patients at high risk of infections, coagulation disorders and previous abdominal surgery interventions. Based on risk assessment, during the procedure as part of surveillance, the radiologists should pay attention to several complications, such as vascular, biliary, mechanical and infectious. Multiphase CT is an imaging tool chosen in emergency settings. The radiologist should report technical success, treatment efficacy, and complications. The complications should be assessed according to well-defined classification systems, and these complications should be categorized consistently according to severity and time of occurrence.

A Narrative Review of Ultrasound Technologies for the Prediction of Neoadjuvant Chemotherapy Response in Breast Cancer.

The incidence and mortality rate of breast cancer (BC) in women currently ranks first worldwide, and neoadjuvant chemotherapy (NAC) is widely used in patients with BC. A variety of imaging assessment methods have been used to predict and evaluate the response to NAC. Ultrasound (US) has many advantages, such as being inexpensive and offering a convenient modality for follow-up detection without radiation emission. Although conventional grayscale US is typically used to predict the response to NAC, this approach is limited in its ability to distinguish viable tumor tissue from fibrotic scar tissue. Contrast-enhanced ultrasound (CEUS) combined with a time-intensity curve (TIC) not only provides information on blood perfusion but also reveals a variety of quantitative parameters; elastography has the potential capacity to predict NAC efficiency by evaluating tissue stiffness. Both CEUS and elastography can greatly improve the accuracy of predicting NAC responses. Other US techniques, including three-dimensional (3D) techniques, quantitative ultrasound (QUS) and US-guided near-infrared (NIR) diffuse optical tomography (DOT) systems, also have advantages in assessing NAC response. This paper reviews the different US technologies used for predicting NAC response in BC patients based on the previous literature.

Abstract 2705: Spatial transcriptomics - a valuable tool to visualize compound effect in precision cut cancer tissue slices (PCCTS)

Abstract The recent advances in immunotherapies, such as immune checkpoint modulators, bispecific antibodies, and adoptive T-cell transfer, opens new opportunities for the treatment of cancer. Having this broad spectrum of new therapeutic agents available, the demand for predictive and robust preclinical models to minimize translational failures in immuno-oncology is increasing. Indivumed has successfully implemented the model of Precision Cut Cancer Tissue Slices (PCCTS) derived from viable human tumor tissue to serve as a platform for testing different applications such as chemotherapeutic agents, small molecules and antibodies. In this study, we investigated the effects of OKT3® (Muromonab), a therapeutic antibody against CD3, on PCCTS from a patient diagnosed with non-small cell lung cancer (NSCLC) in respect of gene expression changes using Spatial Transcriptomics. Spatial Transcriptomics (10x Genomics) is a technique to spatially resolve whole RNA-seq information. Tissue sections were prepared using a Krumdieck Tissue slicer and fresh tissue sections were incubated for 24 h with 10 µg/ml OKT3 followed by performing the Visium Spatial Gene Expression Workflow from 10x Genomics. For this purpose, a glass slide containing spatially barcoded capture probes were used to bind mRNAs of a tissue section. Following cDNA synthesis and library preparation, the libraries were sequenced using standard RNA-seq technology. Specific sequence barcodes allowed to assign gene expression data to the histological positions in the tissue. For visualization of gene expression patterns, the software Space Ranger and Loupe Browser were used. This method enabled the identification of cellular subpopulations in the spatial context before and after treatment with OKT3, whereas molecular identities and positional information of diverse cells would have been lost upon transcriptome analysis of bulk samples. Our data showed significant differences between untreated and OKT3 treated tissue slices especially in the microenvironment that encompasses inflammatory cells, extracellular matrix, and stromal cells interacting with tumor cells for cancer growth and progression. The combination of the PCCTS platform with Spatial Transcriptomics has been shown to be most valuable for the understanding of compound effects. The location of cells and their changes in gene expression patterns are important to understand tissue functionality and corresponding pathological changes. Citation Format: Nicole Kerstedt, Nicole Grabinski, Kristina Bernoth, Monika Schoeppler, Bita Motamedi-Baniassad, Jana Krueger, Moiken Petersen, Hartmut Juhl, Kerstin A. David. Spatial transcriptomics - a valuable tool to visualize compound effect in precision cut cancer tissue slices (PCCTS) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 2705.

Organotypic Slice Cultures as Preclinical Models of Tumor Microenvironment in Primary Pancreatic Cancer and Metastasis.

Realistic preclinical models of primary pancreatic cancer and metastasis are urgently needed to test the therapy response ex vivo and facilitate personalized patient treatment. However, the absence of tumor-specific microenvironment in currently used models, e.g., patient-derived cell lines and xenografts, only allows limited predictive insights. Organotypic slice cultures (OTSCs) comprise intact multicellular tissue, which can be rapidly used for the spatially resolved drug response testing. This protocol describes the generation and cultivation of viable tumor slices of pancreatic cancer and its metastasis. Briefly, tissue is casted in low melt agarose and stored in cold isotonic buffer. Next, tissue slices of 300 µm thickness are generated with a vibratome. After preparation, slices are cultured at an air-liquid interface using cell culture inserts and an appropriate cultivation medium. During cultivation, changes in cell differentiation and viability can be monitored. Additionally, this technique enables the application of treatment to viable human tumor tissue ex vivo and subsequent downstream analyses, such as transcriptome and proteome profiling. OTSCs provide a unique opportunity to test the individual treatment response ex vivo and identify individual transcriptomic and proteomic profiles associated with the respective response of distinct slices of a tumor. OTSCs can be further explored to identify therapeutic strategies to personalize treatment of primary pancreatic cancer and metastasis.

Role of diffusion weighted MRI in patients with hepatocellular carcinoma: prediction and assessment of response to trans-arterial chemoembolization

Aim: The study goal is to detect if apparent diffusion coefficient (ADC), a quantitative parameter of diffusion-weighted imaging (DWI), can recognize HCC post TACE residuals. Results were obtained by using MRI_DWI & ADC and were compared with those of Tri phasic-computed tomography (CT). patient and Methods MRI-DWI was performed to 20 patients with 24 HCC focal lesions before and 1month after TACE to calculate the ADC value of HCC. Patients were also evaluated with Tri phasic-CT after TACE. CT was performed within 1 month after TACE. Results: All patients under the study shows pretreatment restricted Diffusion weighted images with low ADC value. Mean ADC value before treatment was 1.14× 10¯³ ±0.29× 10¯³ and ranged from 0.819× 10¯³ to 2.48× 10¯³. 9 cases (45%) cases show post-TACE good therapeutic response with facilitated diffusion & mean ADC value 1.32×10¯³ with significant increase compared to pre-treatment values. 11 cases (55%) shows post-TACE partial or no therapeutic response with restricted diffusion & mean ADC value 1.18×10¯³. However, there was no statistical significant difference between ADC value of resolved and that of residual cases (P-value=0.067), DWI could predict the response of treatment as CT by 100%. All cases of Good therapeutic response had a facilitated diffusion, all cases of partial therapeutic response had a restricted diffusion but less than pretreatment and all cases with no therapeutic response had a restricted diffusion but more than pretreatment. Conclusion DWI could evaluate HCC necrosis of tumor after chemoembolization, and the ADC importance might be its ability to detect viable necrotic tumor tissues. Furthermore, DWI-MRI determines improved liver lesion location. So, DWI can be used as an option for HCC patients short term follow up after chemoembolization and may direct patient control for decreasing radiation CT examination exposure and the danger of contrast material-induced nephropathy.