Hypoxia is a common feature of the tumor microenvironment, including that of triple-negative breast cancer (TNBC), an aggressive breast cancer subtype with a high five-year mortality rate. Using [18F]-fluoromisonidazole (FMISO) positron emission tomography (PET) imaging, we aimed to monitor changes in response to immunotherapy (IMT) with chemotherapy in TNBC. TNBC-tumor-bearing mice received paclitaxel (PTX) ± immune checkpoint inhibitors anti-programmed death 1 and anti-cytotoxic T-lymphocyte 4. FMISO-PET imaging was performed on treatment days 0, 6, and 12. Max and mean standard uptake values (SUVmax and SUVmean, respectively), histological analyses, and flow cytometry results were compared. FMISO-PET imaging revealed differences in tumor biology between treatment groups prior to tumor volume changes. 4T1 responders showed SUVmean 1.6-fold lower (p = 0.02) and 1.8-fold lower (p = 0.02) than non-responders on days 6 and 12, respectively. E0771 responders showed SUVmean 3.6-fold lower (p = 0.001) and 2.7-fold lower (p = 0.03) than non-responders on days 6 and 12, respectively. Immunohistochemical analyses revealed IMT plus PTX decreased hypoxia and proliferation and increased vascularity compared to control. Combination IMT/PTX recovered the loss of CD4+ T-cells observed with single-agent therapies. PET imaging can provide timely, longitudinal data on the TNBC tumor microenvironment, specifically intratumoral hypoxia, predicting therapeutic response to IMT plus chemotherapy.

Questions and concerns regarding the efficacy and immunogenicity of coronavirus disease 2019 (COVID-19) vaccines have plagued scientists since the BNT162b2 mRNA vaccine was introduced in late 2020. As a result, decisions about vaccine boosters based on breakthrough infection rates and the decline of antibody titers have commanded worldwide attention and research. COVID-19 patients have displayed continued severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-spike-protein-specific antibodies and neutralizing antibodies in longitudinal studies; in addition, cytokine activation has been detected at early steps following SARS-CoV-2 infection. Epitopes that are highly reactive and can mediate long-term antibody responses have been identified at the spike and ORF1ab proteins. The N-terminal domain of the S1 and S2 subunits is the location of important SARS-CoV-2 spike protein epitopes. High sequence identity between earlier and newer variants of SARS-CoV-2 and different degrees of sequence homology among endemic human coronaviruses have been observed. Understanding the extent and duration of protective immunity is consequential for determining the course of the COVID-19 pandemic. Further knowledge of memory responses to different variants of SARS-CoV-2 is needed to improve the design of the vaccine.

Our results from quantitative RT-PCR, Western blotting, immunohistochemistry, and the tissue microarray of medullary thyroid cancer (MTC) cell lines and patient specimens confirm that VGSC subtype NaV1.7 is uniquely expressed in aggressive MTC and not expressed in normal thyroid cells and tissues. We establish the druggability of NaV1.7 in MTC by identifying a novel inhibitor (SV188) and investigate its mode of binding and ability to inhibit INa current in NaV1.7. The whole-cell patch-clamp studies of the SV188 in the NaV1.7 channels expressed in HEK-293 cells show that SV188 inhibited the INa current in NaV1.7 with an IC50 value of 3.6 µM by a voltage- and use-dependent blockade mechanism, and the maximum inhibitory effect is observed when the channel is open. SV188 inhibited the viability of MTC cell lines, MZ-CRC-1 and TT, with IC50 values of 8.47 μM and 9.32 μM, respectively, and significantly inhibited the invasion of MZ-CRC-1 cells by 35% and 52% at 3 μM and 6 μM, respectively. In contrast, SV188 had no effect on the invasion of TT cells derived from primary tumor, which have lower basal expression of NaV1.7. In addition, SV188 at 3 μM significantly inhibited the migration of MZ-CRC-1 and TT cells by 27% and 57%, respectively.

Background: Novel immune-promoting therapeutics for glioblastoma multiforme (GBM), such as oncolytic herpes simplex viruses (oHSV) and immune checkpoint inhibitors (ICI), have the potential to improve overall survival and lead to long-term remission, however their clinical benefit remains inconsistent. Under standard of care imaging, assessment of immunotherapeutic response can be limited by apparent radiological tumor progression associated with treatment-induced inflammation and immune infiltration. This has led to a need for better understanding of immune cell dynamics and immunotherapy response in GBM. The objective of this study is to evaluate changes in CD8+ infiltration and its relation to therapy response, through positron emission tomography (PET) imaging, in preclinical GBM. Methods: GSC005-luc orthotopic GBM models (n= 40) were treated with saline, M002 oHSV, anti-PD1 or combination immunotherapy following three weeks of tumor growth. One-week post-treatment, [89Zr]-CD8 PET imaging was performed and biologically validated through ex vivo PET, autoradiography and staining for H&E and CD8 immunohistochemistry (IHC). Further, longitudinal changes in CD8 infiltration were evaluated via [89Zr]-CD8 PET imaging one- and three-weeks post-immunotherapy with responses monitored every three days via bioluminescence imaging (BLI). Statistical analysis involved one-way ANOVA and unpaired T-test, with p<0.05 considered significant. Results: Linear correlations were seen between in vivo PET signal and ex vivo uptake (r=0.61, p<0.01), autoradiography (r=0.46, p<0.01), and IHC tumor CD8+ cell density (r=0.55, p<0.01) one-week post-treatment. Immunotherapy efficacy, defined by decreased BLI signal, resembled clinical findings as only a subset of mice exhibited long-term positive response measured by BLI signal decrease (n=9/24). Response classification revealed increased CD8+ cell tumor localization, as measured by peak standardized uptake value (SUVpeak) tumor to background ratio (TBR), in non-responders (p<0.01) and decreased heterogeneity in signal distribution in responders (p<0.05) relative to controls early in the course of therapy. Conclusions: Early CD8 infiltration and uptake distribution from CD8-PET imaging provides potential imaging metrics of therapeutic response to oHSV immunotherapy in GBM. Development of these immune-focused imaging approaches for the assessment of positive immunotherapeutic effects in GBM is beneficial for the better understanding of immune cell dynamics and their relation to clinical outcomes. Citation Format: Carlos A. Gallegos, Yun Lu, Alessandro Mascioni, Fang Jia, Jennifer C. Clements, Patrick N. Song, Shannon E. Lynch, Jason M. Warram, James M. Markert, Anna Sorace. Molecular imaging of CD8 infiltration following combination immunotherapy in preclinical glioblastoma. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 3576.