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Oncolytic virotherapy aims to activate host antitumor immunity, but the effectiveness of current intratumoral herpes-simplex virus (HSV) based monotherapy is limited. Here, to boost the potency of cancer cell targeting α-herpesviruses derived from HSV or Varicella-Zoster Virus (VZV), we coinjected them with myeloid cell-tropic β-herpesviruses derived from cytomegalovirus (CMV) which can powerfully modulate immune responses. Co-administered CMV was shown to promote intratumoral replication of HSV, increase local release of pro-inflammatory cytokines, inhibit adaptive antiviral immune responses, enhance systemic antitumor responses, and lead to superior control of both injected and contralateral tumors. CMV-encoded myeloid-tropic genes, NK evasins (i.e. the vMHC-I homolog), and the m02-m16 region (involved in downregulating classical MHC-I) were implicated in enhancing antitumor activities. CMV is a promising adjuvant to reshape and enhance the antitumor immune responses following α-herpesvirus therapy.

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Although chimeric antigen receptor T (CART)–cell therapy has been successful in treating certain hematologic malignancies, wider adoption of CART-cell therapy is limited because of minimal activity in solid tumors and development of life-threatening toxicities, including cytokine release syndrome (CRS). There is a lack of a robust, clinically relevant imaging platform to monitor in vivo expansion and trafficking to tumor sites. To address this, we utilized the sodium iodide symporter (NIS) as a platform to image and track CART cells. We engineered CD19-directed and B-cell maturation antigen (BCMA)–directed CART cells to express NIS (NIS+CART19 and NIS+BCMA-CART, respectively) and tested the sensitivity of 18F-TFB-PET to detect trafficking and expansion in systemic and localized tumor models and in a CART-cell toxicity model. NIS+CART19 and NIS+BCMA-CART cells were generated through dual transduction with two vectors and demonstrated exclusive 125I uptake in vitro. 18F-TFB-PET detected NIS+CART cells in vivo to a sensitivity level of 40,000 cells. 18F-TFB-PET confirmed NIS+BCMA-CART-cell trafficking to the tumor sites in localized and systemic tumor models. In a xenograft model for CART-cell toxicity, 18F-TFB-PET revealed significant systemic uptake, correlating with CART-cell in vivo expansion, cytokine production, and development of CRS-associated clinical symptoms. NIS provides a sensitive, clinically applicable platform for CART-cell imaging with PET scan. 18F-TFB-PET detected CART-cell trafficking to tumor sites and in vivo expansion, correlating with the development of clinical and laboratory markers of CRS. These studies demonstrate a noninvasive, clinically relevant method to assess CART-cell functions in vivo.

Supplementary Table S1

Eligibility criteria to ensure pet dogs meet physical and laboratory candidacy for entry into this clinical trial

Summary of viral shedding in a variety of biological samples

A summary of canine patient disease types and methods to assess disease burden

Summary of viral transgene expression as assessed by measurement of human IFN-beta

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Representative histological sections of tumor removed from patient UTK01

Purpose: Attenuated measles viruses are promising experimental anticancer agents currently being evaluated in a phase I dose escalation trial for ovarian cancer patients. Virus attachment, entry, and subsequent intercellular fusion between infected and uninfected neighboring cells are mediated via the two measles receptors (CD46 and SLAM). To minimize potential toxicity due to measles virus–associated immunosuppression and infection of nontarget tissues, we sought to develop an ovarian cancer exclusive fully retargeted measles virus.Experimental Design and Results: Interactions of measles virus with its natural receptors were ablated, and a single-chain antibody (scFv) specific for α-folate receptor (FRα), a target overexpressed on 90% of nonmucinous ovarian cancer, was genetically engineered on the viral attachment protein (MV-αFR). Specificity of virus tropism was tested on tumor and normal cells. Biodistribution of measles virus infection was evaluated in measles-susceptible CD46 transgenic mice, whereas antitumor activity was monitored noninvasively by bioluminescence imaging in xenograft models. Tropism and fusogenic activity of MV-αFR was redirected exclusively to FRα without compromise to virus infectivity. In contrast to the parental virus, MV-αFR has no background infectivity on normal human cells. The antitumor activity of MV-αFR, as assessed by tumor volume reduction and overall survival increase, was equal to the parental virus in two models of human ovarian cancer (s.c. and i.p.).Conclusions: A FR-exclusive ovarian cancer targeted oncolytic virus was generated and shown to be therapeutically effective, thus introducing a new modality for FR targeting and a candidate measles virus for clinical testing.

Supplementary Figure 1 from Retargeted Oncolytic Measles Strains Entering via the EGFRvIII Receptor Maintain Significant Antitumor Activity against Gliomas with Increased Tumor Specificity

Among the best-characterized genetic alterations in gliomas is the amplification of the epidermal growth factor receptor (EGFR) gene, present in ∼40% of glioblastoma multiforme, and frequently associated with the EGFRvIII gene rearrangement. We have previously shown that attenuated vaccine strains of measles virus have potent antitumor activity against gliomas, and identified H protein mutations, which ablate recognition of the natural measles virus receptors CD46 and SLAM. Retargeted recombinant viruses were generated from the measles Edmonston-NSe vaccine strain displaying a single-chain antibody against EGFRvIII at the COOH terminus of H and containing the marker green fluorescent protein (GFP) gene in position 1. Two different H mutants were employed: HSNS (V451S, Y481N, and A527S)-CD46 blind, and HAA (Y481A and R533A)-CD46 and SLAM blind. MV-GFP virus was used as a positive control. Both EGFRvIII-retargeted viruses had significant antitumor activity against EGFRvIII-expressing glioblastoma multiforme but no cytopathic effect against normal cells. In an orthotopic model of EGFRvIII-expressing GBM39 xenografts, there was comparable therapeutic efficacy between retargeted strains and unmodified MV-GFP and statistically significant prolongation of survival in treated animals compared with the control group (P = 0.001). Formation of syncytia was observed in tumors treated with retargeted viruses, with a surrounding infiltrate consisting of macrophages and natural killer cells. In summary, EGFRvIII-retargeted oncolytic measles virus strains have comparable therapeutic efficacy with the unmodified MV-GFP strain against EGFRvIII-expressing glioma lines and xenografts with improved therapeutic index, a finding with potential translational implications in glioma virotherapy. (Cancer Res 2006; 66(24): 11840-50)

Supplementary Figure Legend from Retargeted Oncolytic Measles Strains Entering via the EGFRvIII Receptor Maintain Significant Antitumor Activity against Gliomas with Increased Tumor Specificity

Supplementary Figure 1 from Phase I Trial of Intraperitoneal Administration of an Oncolytic Measles Virus Strain Engineered to Express Carcinoembryonic Antigen for Recurrent Ovarian Cancer

Supplementary Figure 4 from Phase I Trial of Intraperitoneal Administration of an Oncolytic Measles Virus Strain Engineered to Express Carcinoembryonic Antigen for Recurrent Ovarian Cancer

Supplementary Figure Legends 1-5 from Phase I Trial of Intraperitoneal Administration of an Oncolytic Measles Virus Strain Engineered to Express Carcinoembryonic Antigen for Recurrent Ovarian Cancer

Supplementary Figure 5 from Phase I Trial of Intraperitoneal Administration of an Oncolytic Measles Virus Strain Engineered to Express Carcinoembryonic Antigen for Recurrent Ovarian Cancer

Supplementary Figure 2 from Phase I Trial of Intraperitoneal Administration of an Oncolytic Measles Virus Strain Engineered to Express Carcinoembryonic Antigen for Recurrent Ovarian Cancer

Supplementary Figure 3 from Phase I Trial of Intraperitoneal Administration of an Oncolytic Measles Virus Strain Engineered to Express Carcinoembryonic Antigen for Recurrent Ovarian Cancer

Supplementary Table 1 from Phase I Trial of Intraperitoneal Administration of an Oncolytic Measles Virus Strain Engineered to Express Carcinoembryonic Antigen for Recurrent Ovarian Cancer

Although chimeric antigen receptor T (CART)–cell therapy has been successful in treating certain hematologic malignancies, wider adoption of CART-cell therapy is limited because of minimal activity in solid tumors and development of life-threatening toxicities, including cytokine release syndrome (CRS). There is a lack of a robust, clinically relevant imaging platform to monitor in vivo expansion and trafficking to tumor sites. To address this, we utilized the sodium iodide symporter (NIS) as a platform to image and track CART cells. We engineered CD19-directed and B-cell maturation antigen (BCMA)–directed CART cells to express NIS (NIS+CART19 and NIS+BCMA-CART, respectively) and tested the sensitivity of 18F-TFB-PET to detect trafficking and expansion in systemic and localized tumor models and in a CART-cell toxicity model. NIS+CART19 and NIS+BCMA-CART cells were generated through dual transduction with two vectors and demonstrated exclusive 125I uptake in vitro. 18F-TFB-PET detected NIS+CART cells in vivo to a sensitivity level of 40,000 cells. 18F-TFB-PET confirmed NIS+BCMA-CART-cell trafficking to the tumor sites in localized and systemic tumor models. In a xenograft model for CART-cell toxicity, 18F-TFB-PET revealed significant systemic uptake, correlating with CART-cell in vivo expansion, cytokine production, and development of CRS-associated clinical symptoms. NIS provides a sensitive, clinically applicable platform for CART-cell imaging with PET scan. 18F-TFB-PET detected CART-cell trafficking to tumor sites and in vivo expansion, correlating with the development of clinical and laboratory markers of CRS. These studies demonstrate a noninvasive, clinically relevant method to assess CART-cell functions in vivo.

Reporter gene imaging (RGI) can accelerate development timelines for gene and viral therapies by facilitating rapid and noninvasive in vivo studies to determine the biodistribution, magnitude, and durability of viral gene expression and/or virus infection. Functional molecular imaging systems used for this purpose can be divided broadly into deep-tissue and optical modalities. Deep-tissue modalities, which can be used in animals of any size as well as in human subjects, encompass single photon emission computed tomography (SPECT), positron emission tomography (PET), and functional/molecular magnetic resonance imaging (f/mMRI). Optical modalities encompass fluorescence, bioluminescence, Cerenkov luminescence, and photoacoustic imaging and are suitable only for small animal imaging. Here we discuss the mechanisms of action and relative merits of currently available reporter gene systems, highlighting the strengths and weaknesses of deep tissue versus optical imaging systems and the hardware/reagents that are used for data capture and processing. In light of recent technological advances, falling costs of imaging instruments, better availability of novel radioactive and optical tracers, and a growing realization that RGI can give invaluable insights across the entire in vivo translational spectrum, the approach is becoming increasingly essential to facilitate the competitive development of new virus- and gene-based drugs., Graphical abstract, Reporter gene imaging can accelerate the clinical translation and development of oncolytic virotherapy and gene therapy vectors. Here we review common reporter genes for radionuclide, magnetic resonance, and optical imaging modalities. We highlight the elegance of the sodium iodide symporter (NIS) that is amenable to SPECT or PET imaging in mice, large animals, and humans.

Oncolytic virus therapy leads to immunogenic death of virus-infected tumor cells and this has been shown in preclinical models to enhance the cytotoxic T-lymphocyte response against tumor-associated antigens (TAAs), leading to killing of uninfected tumor cells. To investigate whether oncolytic virotherapy can increase immune responses to tumor antigens in human subjects, we studied T-cell responses against a panel of known myeloma TAAs using PBMC samples obtained from ten myeloma patients before and after systemic administration of an oncolytic measles virus encoding sodium iodide symporter (MV-NIS). Despite their prior exposures to multiple immunosuppressive antimyeloma treatment regimens, T-cell responses to some of the TAAs were detectable even before measles virotherapy. Measurable baseline T-cell responses against MAGE-C1 and hTERT were present. Furthermore, MV-NIS treatment significantly (P

Virus neutralizing antibody (vnAb) titers are the strongest laboratory correlate of protection from SARS-CoV-2. Providing individuals with real-time measures of their vnAb titers is predicted to improve their ability to make personal wellness decisions. Yet, widespread commercial testing of SARS-CoV-2 vnAbs does not currently occur. Here, we examined whether knowing their vnAb titer impacted wellness decision-making among individuals. To this end, starting on January 1, 2021, we offered all employees from two companies free IMMUNO-COV™ testing and conducted a survey to assess their behaviors and decisions regarding booster vaccination. IMMUNO-COV is a clinically validated, surrogate virus assay that quantitates serum titers of SARS-CoV-2 vnAbs. To help participants gauge their level of protection based on their vnAb titer, we calibrated IMMUNO-COV titers to the World Health Organization (WHO) International Standard (IU/mL), making them comparable to published reports of correlates of protection, and we fit historical IMMUNO-COV vnAb titer values into predictive models of immune protection from COVID-19. As expected, data for the 56 program participants showed variability in vnAb titers post vaccination, rates vnAb decay, and fold-increases in vnAb titers after booster vaccination. Based on the participant survey, the majority (66%) of participants indicated that knowing their vnAb titer impacted their social behaviors and/or their decision on the timing of a booster vaccination. Several participants indicated that knowing their vnAb titer contributed to their peace of mind regarding their high level of protection from COVID-19. Together, these data demonstrate that regular determination of SARS-CoV-2 neutralizing antibody titers can significantly impact decisions regarding social interactions and timing of booster vaccinations.

Oncologic viruses (OV) can induce tumor death through both direct oncolysis and immune-mediated destruction. Our study investigates the use of a novel OV with a Vesicular Stomatitis Virus (VSV) vector modified to express interferon-beta (IFN-b) and Tyrosinase Related Protein 1 (TYRP1) (VSV-IFNb-TYRP1). VSV is an attractive vector since humans are not naturally infected with VSV; thus, pre-existing immunity is minimal. IFN-b leads to increased T-cell responses and tumor cell apoptosis, while TYRP1, a melanocyte differentiation antigen, increases immunogenicity of the therapy. We conducted a Phase 1 clinical trial with a 3+3 design in patients with metastatic uveal melanoma. VSV-IFNb-TYRP1 was injected into a liver metastasis under image guidance, then administered on the same day as a single intravenous (IV) infusion. IV doses started at dose level (DL) 1 1 × 1010 TCID50, then escalated to DL2 3 × 10 10, DL3 1 × 1011, and DL4 3 × 1011. The dose delivered intratumorally (IT) varied based on the IV dose. The primary endpoints were safety and maximum tolerated dose (MTD). Efficacy was a secondary endpoint. Correlative studies focused on understanding viral pharmacokinetics (PK) and immunological responses induced by VSV-IFNb-TYRP1 therapy. Twelve patients with previously treated metastatic uveal melanoma were enrolled. Median follow up was 19.1 months. Four DLs were evaluated with one patient at DL4 experiencing dose limiting toxicities (DLTs), including decreased platelet count (grade 3), increased aspartate aminotransferase (AST), and cytokine release syndrome (CRS). Non-DLTs at DL4 were fatigue, fever, CRS, hematological toxicities (decreased platelets and lymphocytes), and AST elevation. Four patients had stable disease (SD) and 8 had progressive disease (PD) as their best response. ELIspot data show that three of the four patients with response to TYRP1 also had a response to gp100, suggesting possible epitope spreading. These four patients received immune checkpoint inhibitor treatment as the next line of therapy, which led to clinical benefit for two patients. Our study evaluated VSV-IFNb-TYRP1 administered via IT and IV routes in a previously treated population of metastatic uveal melanoma patients and found no major safety events. Although there were no clear objective responses to VSV-IFNb-TYRP1, dose-dependent immunogenicity to melanoma antigens was seen. While OV response alone is not sufficient for clinical benefit, the evidence of epitope spreading is encouraging. Future studies of VSV-IFNb-TYRP1 will evaluate combinations with other therapies. Citation Format: Katherine E. Smith, Adam Weisbrod, Carrie Strand, Jacob Allerd, Jose S. Pulido, Alysha Newsom, Lianwen Zhang, Nandakumar Packiriswamy, Heather Montane, Lisa Kottschade, Anastasios Dimou, Yiyi Yan, Markovic Svetomir, Kah Whye Peng, Richard G. Vile, Matthew S. Block, Roxana S. Dronca. Phase I trial of vesicular stomatitis virus expressing human interferon beta and tyrosinase related protein 1 (VSV-IFNb-TYRP1) in metastatic ocular melanoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 2 (Clinical Trials and Late-Breaking Research); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(8_Suppl):Abstract nr CT207.

TPS657 Background: Poorly differentiated neuroendocrine carcinoma (NEC) is an aggressive malignancy comprising both pulmonary and extrapulmonary primary sites. NEC includes both small cell lung cancer (SCLC) and large cell neuroendocrine carcinoma (LCNEC), as well as other neuroendocrine carcinomas arising from any primary organ. A substantial portion (~40%) of NEC arises from gastrointestinal primary sites. The optimal systemic therapy beyond first line platinum and etoposide is not established. There is a critical need to improve upon the median survival in the second line, as most patients do not survive more than 6 months. The efficacy of single agent immune checkpoint inhibitors (ICIs) in NEC has been disappointing. One possible explanation for this is that the tumor microenvironment in NEC is non-inflamed. VSV-IFNβ-NIS is a vesicular stomatitis virus (VSV)-based oncolytic virus being tested in multiple early phase clinical trials. Preliminary studies of immune responses in patients receiving VSV-IFNβ-NIS therapy suggest some patients develop T cell responses to viral antigens and known tumor antigens. We hypothesize that VSV-IFNβ-NIS therapy may convert a non-inflamed or immune-excluded phenotype in NEC to a highly inflamed phenotype that sensitizes the tumor to ICIs. Methods: This is a phase 1-2 safety run-in study designed to determine the safety of VSV-IFNβ-NIS in combination with a single agent ICI, pembrolizumab, followed by dose expansion in patients with refractory non-small cell lung cancer (NSCLC) or NEC. The safety run-in portion of this study has been completed, and we are presently testing the recommended phase 2 dose (RP2D) of VSV-IFNβ-NIS in an expansion cohort of patients with SCLC or NEC of any primary site. Patients must have previously progressed on at least one line of systemic therapy. Prior treatment with checkpoint inhibitors is permitted. Patients are treated one time with the RP2D of 1.0x10^11 TCID50 VSV-IFNβ-NIS on day 1, followed by pembrolizumab on day 8 and then pembrolizumab every 21 days until progression, up to 2 years. The primary objective is to estimate the response rate by RECIST 1.1. Secondary objectives include estimation of disease-control rate, duration or response, progression-free survival, overall survival, and safety signals. The NEC expansion cohort will seek to enroll 10 patients. If at least one objective response is observed, and safety is confirmed, the regimen will be considered for future study. Clinical trial information: NCT03647163 .

BackgroundOncolytic viruses (OVs) show significant potential for treating tumors alongside immunotherapies.1 VV1 is an OV derived from the innocuous vesicular stomatitis virus (VSV). VV1 has been engineered to expresses human interferon (IFN) β and thyroidal sodium iodide symporter (NIS).2 VV1-infected cells produce IFNβ, which protects non-cancer cells from VV1 and allows VV1 to spread more efficiently in cancerous tissue.3 4 NIS expression on cells imports 99mTc pertechnetate, which facilitates in vivo imaging of virus infection.2 This three-part, phase 1–2 study was designed to determine the safety and tolerability of VV1 in patients with advanced unresectable and metastatic solid tumors. Here we report on the second part of this study: selection of recommended phase 2 regimen (RP2D), comprising further assessment of both duration and dose.MethodsPatients (n=29) were enrolled to receive a single IV infusion of VVI monotherapy. 23 patients received IV VV1 1.7 x1010 TCID50 over 15, 30, 60 or 180 min. Six patients received 1.0 x1011 TCID50 over 30 min with aggressive premedication and fluid support overnight. Patients were monitored for dose limiting toxicities over 21 days with efficacy assessments after 6 weeks and then every 3 months for survival. The primary objective was to establish the safety and tolerability of IV VV1. Secondary objectives included preliminary efficacy, pharmacokinetics and pharmacodynamics.ResultsIn this study VV1, demonstrated an acceptable safety profile. No deaths or Grade 4 infusion-related reactions (IRR) were reported. VV1 shedding by buccal swabs was negative at all study visits. Peak IFNβ serum levels and preliminary efficacy signals (2 PRs) were associated with 30 min infusion duration and higher dose, with RECIST data pending for 1 x 1011(table 1).Abstract 505 Table 1ConclusionsIn this study, the absence of viral shedding demonstrates that VV1 is safe for patient and caregiver with little/no environmental impact. There was no difference in safety between the lower and the higher dose infusions. In this patient population acceptable tolerability was observed at the higher dose with 30 min duration, thus the RP2D is 1x 1011 over 30 mins.Trial RegistrationNCT02923466ReferencesHemminki O, Dos Santos JM, Hemminki A. Oncolytic viruses for cancer immunotherapy. J Hematol Oncol 2020;13(1):84.Naik S, Nace R, Federspiel MJ, Barber GN, Peng KW, Russell SJ. Curative one-shot systemic virotherapy in murine myeloma. Leukemia 2012;26(8):1870–1878.Barber GN. Vesicular stomatitis virus as an oncolytic vector. Viral Immunol 2004;17(4):516–527.Lichty BD, Power AT, Stojdl DF, Bell JC. Vesicular stomatitis virus: re-inventing the bullet. Trends Mol Med 2004;10(5):210–216.Ethics ApprovalEthics approval was granted by WCG IRB. IRB tracking number: 20163005. Voluntary written informed consent was obtained from every patient prior to participation.

An orally active vaccine capable of boosting SARS-CoV-2 immune responses in previously infected or vaccinated individuals would help efforts to achieve and sustain herd immunity. Unlike mRNA-loaded lipid nanoparticles and recombinant replication-defective adenoviruses, replicating vesicular stomatitis viruses with SARS-CoV-2 spike glycoproteins (VSV-SARS2) were poorly immunogenic after intramuscular administration in clinical trials. Here, by G protein trans-complementation, we generated VSV-SARS2(+G) virions with expanded target cell tropism. Compared to parental VSV-SARS2, G-supplemented viruses were orally active in virus-naive and vaccine-primed cynomolgus macaques, powerfully boosting SARS-CoV-2 neutralizing antibody titers. Clinical testing of this oral VSV-SARS2(+G) vaccine is planned.

The treatment focus for multiple myeloma (MM) has recently pivoted towards immune modulating strategies, with T-cell redirection therapies currently at the forefront of drug development. Yet, despite this revolution in treatment, MM remains without a sustainable cure. At the same time, tremendous advancement has been made in recombinant and gene editing techniques for oncolytic viruses (OV), which have increased their tumor specificity, improved safety, and enhanced the oncolytic and immunostimulatory potential. These breakthrough developments in oncolytic virotherapy have opened new avenues for OVs to be used in combination with other immune-based therapies such as checkpoint inhibitors, chimeric antigen receptor T-cells (CAR-T) and bispecific T-cell engagers. In this review, the authors place the spotlight on systemic oncolytic virotherapy as an adaptable immunotherapeutic for MM, highlight the unique mechanism of OVs in activating the immune-suppressive marrow microenvironment, and lastly showcase the OV platforms and the promising combination strategies in the pipeline for MM.

Noninvasive dual-imaging methods that provide an early readout on tumor permissiveness to virus infection and tumor cell death could be valuable in optimizing development of oncolytic virotherapies. Here, we have used the sodium iodide symporter (NIS) and 125I radiotracer to detect infection and replicative spread of an oncolytic vesicular stomatitis virus (VSV) in VSV-susceptible (MPC-11 tumor) versus VSV-resistant (CT26 tumor) tumors in BALB/c mice. In conjunction, tumor cell death was imaged simultaneously using technetium (99mTc)-duramycin that binds phosphatidylethanolamine in apoptotic and necrotic cells. Dual-isotope single-photon emission computed tomography/computed tomography (SPECT/CT) imaging showed areas of virus infection (NIS and 125I), which overlapped well with areas of tumor cell death (99mTc-duramycin imaging) in susceptible tumors. Multiple infectious foci arose early in MPC-11 tumors, which rapidly expanded throughout the tumor parenchyma over time. There was a dose-dependent increase in numbers of infectious centers and 99mTc-duramycin-positive areas with viral dose. In contrast, NIS or duramycin signals were minimal in VSV-resistant CT26 tumors. Combinatorial use of NIS and 99mTc-duramycin SPECT imaging for simultaneous monitoring of oncolytic virotherapy (OV) spread and the presence or absence of treatment-associated cell death could be useful to guide development of combination treatment strategies to enhance therapeutic outcome.

Recent measles epidemics in US and European cities where vaccination coverage has declined are providing a harsh reminder for the need to maintain protective levels of immunity across the entire population. Vaccine uptake rates have been declining in large part because of public misinformation regarding a possible association between measles vaccination and autism for which there is no scientific basis. The purpose of this article is to address a new misinformed antivaccination argument-that measles immunity is undesirable because measles virus is protective against cancer. Having worked for many years to develop engineered measles viruses as anticancer therapies, we have concluded (1) that measles is not protective against cancer and (2) that its potential utility as a cancer therapy will be enhanced, not diminished, by prior vaccination.

Targeting the B-cell receptor and phosphatidylinositol 3-kinase/mTOR signaling pathways has shown meaningful, but incomplete, antitumor activity in lymphoma. Glycogen synthase kinase 3 (GSK3) α and β are 2 homologous and functionally overlapping serine/threonine kinases that phosphorylate multiple protein substrates in several key signaling pathways. To date, no agent targeting GSK3 has been approved for lymphoma therapy. We show that lymphoma cells abundantly express GSK3α and GSK3β compared with normal B and T lymphocytes at the messenger RNA and protein levels. Utilizing a new GSK3 inhibitor 9-ING-41 and by genetic deletion of GSK3α and GSK3β genes using CRISPR/CAS9 knockout, GSK3 was demonstrated to be functionally important to lymphoma cell growth and proliferation. GSK3β binds to centrosomes and microtubules, and lymphoma cells treated with 9-ING-41 become arrested in mitotic prophase, supporting the notion that GSK3β is necessary for the progression of mitosis. By analyzing recently published RNA sequencing data on 234 diffuse large B-cell lymphoma patients, we found that higher expression of GSK3α or GSK3β correlates well with shorter overall survival. These data provide rationale for testing GSK3 inhibitors in lymphoma patient trials.

New immuno-oncology therapies are improving cancer treatments beyond the former standard of care, as evidenced by the recent and continuing clinical approvals for immunotherapies in a broad range of indications. However, a majority of patients (particularly those with immunologically cold tumors) still do not benefit, highlighting the need for rational combination approaches. Oncolytic viruses (OV) both directly kill tumor cells and inflame the tumor microenvironment. While OV spread can be limited by the generation of antiviral immune responses, the initial local tumor cell killing can reverse the immunosuppressive tumor microenvironment, resulting in more effective release of tumor-associated antigens (TAAs), cross-presentation, and antitumoral effector T cell recruitment. Moreover, many OVs can be engineered to express immunomodulatory genes. Rational combination approaches to cancer immunotherapy include the use of OVs in combination with immune checkpoint inhibitors (ICIs) or adoptive T cell therapy (ACT) to promote sustained antitumoral immune responses. OV combinations have additive or synergistic efficacy in preclinical tumor models with ICIs or ACT. Several preclinical studies have confirmed systemic reactivation and proliferation of adoptively transferred antitumoral T cells in conjunction with oncolytic OVs (expressing cytokines or TAAs) resulting from the specific tumor cell killing and immunostimulation of the tumor microenvironment which leads to increased tumor trafficking, activity, and survival. Recent clinical trials combining OVs with ICIs have shown additive effects in melanoma. Additional clinical data in an expanded range of patient indications are eagerly awaited. The relative timings of OV and ICI combination remains under-studied and is an area for continued exploration. Studies systematically exploring the effects of systemic ICIs prior to, concomitantly with, or following OV therapy will aid in the future design of clinical trials to enhance efficacy and increase patient response rates.

TPS9595 Background: There is a need for novel immunotherapies to address the patient population that never or no longer responds to immune checkpoint inhibitors (CPI). VV1 is an oncolytic vesicular stomatitis virus engineered to express human interferon beta (IFNβ) to enhance cellular anti-tumor immune responses and tumor selectivity. Phase 1 studies demonstrated VV1 anti-tumor activity in several malignancies with or without a CPI. We are exploring ways to optimize VV1 efficacy in combination with cemiplimab, an anti-PD1 antibody approved for lung, basal and squamous cell skin cancers. Recent clinical data support a 5-fold higher dose of VV1 than was previously explored, and pre-clinical data show synergy between the oncolytic and an anti-CTLA4 antibody, in addition to cemiplimab, supporting exploration of a triplet. What was originally a five-arm study of intravenous (IV) VV1 in combination with IV cemiplimab has been amended to focus on 2 means of optimizing efficacy: use of a higher dose of VV1 and triplet combination in proof-of-concept populations. Methods: We are now enrolling pts with advanced melanoma (after progression on anti-PD1) and plan to include 1st-line NSCLC pts with PD-L1 expression ≥50%. The study is first exploring the preliminary anti-tumor activity, safety, and immunogenic activity of the combination of IV VV1 at a dose of 1.0 x 1011 TCID50 once on D1 followed by IV cemiplimab Q3W starting on D8, or the same regimen with an additional intratumoral injection of VV1 1.0 x 109 TCID50 once on D1 for pts with accessible lesions. Pts receive IV cemiplimab Q3W until confirmed disease progression or intolerable toxicity. Once at least 6 pts have been treated with acceptable safety across the 2 melanoma doublet cohorts using this higher dose of VV1, a 3rd melanoma cohort will open to add a single dose of ipilimumab 50 mg on D1 (all IV triplet). Once 6 melanoma pts have received the triplet safely, the 1st-line NSCLC cohort will open. All cohort decisions are guided by a Data Review Committee. Cohorts will be expanded based on a Simon 2-stage design using a type I error rate of 0.05 and power of 85%. Null ORR is 10% with a target of 35% for 2nd line melanoma and null ORR is 40% in 1st line NSCLC with a target of 70%. Each melanoma cohort will require a response in ≥2 of 10 pts in the 1st stage to add 11 more in the 2nd stage, while NSCLC will first need 5/9 evaluable pts to respond, then an additional 13 to complete the design. Response is assessed at week 7 then Q9W per RECIST v1.1. The study includes serial biopsies in ≥3/10 pts in Stage 1 of each of the IV melanoma cohorts (doublet and triplet therapy), all pts in Stage 2 of these IV melanoma cohorts, and all pts in both Stage 1 and Stage 2 of the IV/IT melanoma cohort, to permit a thorough investigation of the impact of the 3 immunotherapies under investigation. The study is currently ongoing in the USA. Clinical trial information: NCT04291105.

Context This is the first in human Phase 1 dose escalation trial of oncolytic Vesicular Stomatitis Virus (VSV) incorporating interferon beta and sodium iodine symporter transgenes (VSV-IFNβ-NIS) to be administered intravenously in patients with relapsed and refractory hematologic malignancies. Objective The primary objective was to determine the maximum tolerated dose of VSV-IFNβ-NIS as a single agent. The secondary objectives were to determine safety and efficacy of VSV-IFNβ-NIS. Correlative objectives included monitoring viremia and virus shedding. Design This was a 3+3 phase 1 clinical trial from April 2017 to August 2020 including adult patients (pts) with relapsed refractory multiple myeloma (MM), T-cell lymphoma (TCL), or acute myeloid leukemia (AML). Results Fifteen patients received VSV-IFNβ-NIS: MM (7), TCL (7), and AML (1); median age was 64 years, 60% male, and median prior lines of systemic cancer therapies was 5 (range, 2 to 11). Three patients were treated at each dose level (DL) 1 through 3 (respectively 0.05, 0.17, and 0.5 x 1011 TCID50), and 6 at DL 4 (1.7x1011 TCID50). There were no dose-limiting toxicities. Hematologic AEs, particularly lymphopenia (73%) were the predominant grade 3 and 4 AEs. Non-hematologic AE of interest were grade 1 (6.7%) and 2 (46.6%) cytokine release syndrome, of which only 1 patient required transient norepinephrine support. Objective responses were seen in patients with TCL. There was a 3-month partial response (PR) in a patient treated at DL 2 after 11 prior systemic therapies. However, compelling responses were seen at DL 4 with a deepening 6-month PR in a patient with PTCL and ongoing CR, even 14 months after VSV in another patient with cutaneous relapse of PTCL; both patients received 5 prior lines of therapy. Viremia rapidly declined after infusion, and there was no significant viral shedding. Neutralizing anti-VSV antibodies developed by day 29. IFNβ appeared to indicate intratumoral amplification with TCL patients mounting the highest levels. Conclusions A single intravenous dose of VSV-IFNβ-NIS up to 1.7x1011 is safe in heavily pre-treated patients with hematologic malignancies and appears to be most effective as a single agent at DL 4, especially in patients with TCL. Future trials of combination strategies with immune-modulatory drugs are currently being planned. Grant Acknowledgements Mayo Clinic Multiple Myeloma Specialized Program of Research Excellence (SPORE), Grohne gifts, Phillips gift, and Liu gift.

Neutralizing antibodies are key determinants of protection from future infection, yet well-validated high-throughput assays for measuring titers of SARS-CoV-2-neutralizing antibodies are not generally available. Here, we describe the development and validation of IMMUNO-COV v2.0, a scalable surrogate virus assay, which titrates antibodies that block infection of Vero-ACE2 cells by a luciferase-encoding vesicular stomatitis virus displaying SARS-CoV-2 spike glycoproteins (VSV-SARS2-Fluc). Antibody titers, calculated using a standard curve consisting of stepped concentrations of SARS-CoV-2 spike monoclonal antibody, correlated closely (P < 0.0001) with titers obtained from a gold standard 50% plaque-reduction neutralization test (PRNT50%) performed using a clinical isolate of SARS-CoV-2. IMMUNO-COV v2.0 was comprehensively validated using data acquired from 242 assay runs performed over 7 days by five analysts, utilizing two separate virus lots, and 176 blood samples. Assay performance was acceptable for clinical use in human serum and plasma based on parameters including linearity, dynamic range, limit of blank and limit of detection, dilutional linearity and parallelism, precision, clinical agreement, matrix equivalence, clinical specificity and sensitivity, and robustness. Sufficient VSV-SARS2-Fluc virus reagent has been banked to test 5 million clinical samples. Notably, a significant drop in IMMUNO-COV v2.0 neutralizing antibody titers was observed over a 6-month period in people recovered from SARS-CoV-2 infection. Together, our results demonstrate the feasibility and utility of IMMUNO-COV v2.0 for measuring SARS-CoV-2-neutralizing antibodies in vaccinated individuals and those recovering from natural infections. Such monitoring can be used to better understand what levels of neutralizing antibodies are required for protection from SARS-CoV-2 and what booster dosing schedules are needed to sustain vaccine-induced immunity. IMPORTANCE Since its emergence at the end of 2019, SARS-CoV-2, the causative agent of COVID-19, has caused over 100 million infections and 2.4 million deaths worldwide. Recently, countries have begun administering approved COVID-19 vaccines, which elicit strong immune responses and prevent disease in most vaccinated individuals. A key component of the protective immune response is the production of neutralizing antibodies capable of preventing future SARS-CoV-2 infection. Yet, fundamental questions remain regarding the longevity of neutralizing antibody responses following infection or vaccination and the level of neutralizing antibodies required to confer protection. Our work is significant as it describes the development and validation of a scalable clinical assay that measures SARS-CoV-2-neutraling antibody titers. We have critical virus reagent to test over 5 million samples, making our assay well suited for widespread monitoring of SARS-CoV-2-neutralizing antibodies, which can in turn be used to inform vaccine dosing schedules and answer fundamental questions regarding SARS-CoV-2 immunity.

The sodium iodide symporter (NIS) is widely used as a reporter gene to noninvasively monitor the biodistribution and durability of vector-mediated gene expression via gamma scintigraphy, single-photon emission computed tomography (SPECT), and positron-emission tomography (PET). However, the approach is limited by background signal due to radiotracer uptake by endogenous NIS-expressing tissues. In this study, using the SPECT tracer pertechnetate (99mTcO4) and the PET tracer tetrafluoroborate (B18F4), in combination with the NIS inhibitor perchlorate, we compared the transport properties of human NIS and minke whale (Balaenoptera acutorostrata scammoni) NIS in vitro and in vivo. Based on its relative resistance to perchlorate, the NIS protein from minke whale appeared to be the superior candidate reporter gene. SPECT and PET imaging studies in nude mice challenged with NIS-encoding adeno-associated virus (AAV)-9 vectors confirmed that minke whale NIS, in contrast to human and endogenous mouse NIS, continues to function as a reliable reporter even when background radiotracer uptake by endogenous NIS is blocked by perchlorate., Graphical Abstract, Uptake of radioisotopes by endogenous sodium iodide symporter (NIS) limits the efficacy and safety of NIS-mediated bioimaging and radionuclide therapy. Use of the naturally perchlorate-resistant NIS protein from minke whales and the NIS inhibitor perchlorate for in vivo imaging improves image clarity and reduces uptake in endogenous NIS-expressing tissues.