Abstract 3284: HB-201 and HB-202, an arenavirus-based immunotherapy, induces tumor T cell infiltration in patients with HNSCC and other HPV16+ tumors

Background: Human Papillomavirus 16 (HPV16) is the most common etiologic agent of HPV-associated cancers. Treatment options are limited for patients with HPV16+ recurrent or metastatic cancers. HPV16 E7 and E6 oncogenes constitute attractive immunotherapeutic targets. HB-201 and HB-202 are live-attenuated replicating vectors based on LCMV and PICV arenaviruses, respectively, that express the same non-oncogenic HPV16 E7E6 fusion protein for induction of tumor specific T cell responses.

Methods: A Phase I/II open labelled clinical trial of HB-201 single vector therapy and HB-202/HB-201 alternating two-vector therapy in patients with treatment-refractory HPV16+ cancers is currently ongoing (NCT04180215). To assess circulating E6/E7 specific T cell responses, IFN-γ enzyme-linked immunospot (ELISpot) and intracellular cytokine staining were performed on pre- and post-treatment peripheral blood mononuclear cells (PBMCs). Evaluation of T cell infiltration and PD-L1 status in tumor bed was performed on paired tissue biopsies from a subset of patients by multiplex immunofluorescence.

Results: Single vector therapy (HB-201) and alternating two-vector therapy (HB-202/HB-201) rapidly induce high E6/E7 specific T cell levels, reaching up to ~40% of the circulating CD8+ T cell pool. Alternating two-vector therapy seems to maintain E6/E7 specific T cell responses better in continuous dosing compared to single vector therapy. Furthermore, we demonstrate tumor tissue T cell infiltration in more than 50% of patient samples analyzed. Currently, in depth sequencing of paired biopsies is underway to characterize the tumor microenvironment in response to HB-201 and HB-202/HB-201 treatment.

Conclusion: In this updated dataset, we show that HB-201 and HB-202/HB-201, rapidly induce unprecedented E6/E7 specific T cell levels in circulation following a single dose. Furthermore, these data are seen in conjunction with a pronounced increase of post-treatment CD8+ T cells in tumor, suggesting E6/E7 specific T cell infiltration. Our arenavirus vectors expressing the E7E6 fusion antigen demonstrate an attractive and safe therapy for patients with treatment refractory HPV16+ cancers. The ability of replicating arenavirus vectors to incorporate a broad range of antigens and the potent T cell inducing capacity provide a strong rationale to apply this novel therapy to other cancers.

Citation Format: Donna Edwards, Michael Schwendinger, Kia Katchar, Katia Schlienger, Klaus Orlinger, Igor Matushansky, Henning Lauterbach. HB-201 and HB-202, an arenavirus-based immunotherapy, induces tumor T cell infiltration in patients with HNSCC and other HPV16+ tumors [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 3284.

Abstract LB049: Preliminary analysis of immunogenicity of HB-201 and HB-202, an arenavirus-based cancer immunotherapy, in patients with advanced HPV16-positive cancers

Background: Human Papillomavirus 16 (HPV16) is linked to most HPV-associated cancers such as cervical, head and neck, vaginal and anal cancers. Treatment options are limited for patients with HPV16+ recurrent or metastatic cancers. The generation and maintenance of the HPV16+ malignant state requires the stable expression of HPV16-specific E7 and E6 oncogenes, which therefore constitute attractive targets for immunotherapy. HB-201 and HB-202 are both replicating live-attenuated vectors based on arenaviruses LCMV and PICV, respectively, expressing the same non-oncogenic HPV16 E7E6 fusion protein for induction of tumor specific T-cell responses. In preclinical models, administration of HB-201 alone and sequential administration of HB-202 followed by HB-201 was safe and demonstrated potent immunogenicity by induction of E7 and E6 -specific CD8+ T cell responses and efficient tumor control of HPV+ TC-1 tumors. Methods: A first-in-human, Phase I/II open-labelled clinical trial of HB-201 single vector therapy and HB-201 & HB-202 two-vector therapy in patients with treatment-refractory HPV16+ cancers is currently ongoing (NCT04180215). Here, we present first immunogenicity results from the dose escalation phase I of this study. The phase I of the trial is designed to evaluate different dose levels and dosing schedules of HB-201 as a single-vector therapy or as an alternating two-vector therapy together with HB-202. Peripheral blood mononuclear cells (PBMCs) were collected before and after treatment from all patients. PBMCs from a subset of patients were examined for HPV16-specific T cell responses measured by IFN-γ enzyme-linked immunospot. Paired tissue biopsy and serum samples were also collected and being currently evaluated for histology and pharmacokinetics. Results: We demonstrated induction of a directly ex vivo (i.e. no expansion) detectable HPV16-specific T-cell response in PBMCs from patients receiving a single dose of HB-201 or HB-202. Additional exploratory analysis will be available at the time of the meeting. Conclusion: These preliminary data demonstrate for the first time with arenavirus vectors, the induction of HPV16-specific T cells in cancer patients following a single injection of HB-201 or HB-202. Arenavirus vectors expressing E7E6 may constitute a new potential therapy for patients with treatment refractory HPV16+ cancers. Clinical data will be presented in an upcoming scientific meeting. Additional schedules, alternating two-vector therapy with HB-201/HB-202, and combination with anti-PD-1 mAbs are being explored in additional cohorts.

Citation Format: Kia Katchar, Michael Schwendinger, Diane DaSilva, Henning Lauterbach, Klaus Orlinger, Xiaoping Qing, Daniel Pinschewer, Igor Matushansky. Preliminary analysis of immunogenicity of HB-201 and HB-202, an arenavirus-based cancer immunotherapy, in patients with advanced HPV16-positive cancers [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 LB049.

A Randomized Dose-Escalating Phase I Trial of a Replication-Deficient Lymphocytic Choriomeningitis Virus Vector-Based Vaccine Against Human Cytomegalovirus

BACKGROUND

A vaccine (HB-101) consisting of 2 nonreplicating lymphocytic choriomeningitis virus (LCMV) vectors expressing the human cytomegalovirus antigens glycoprotein B (gB) and the 65-kD phosphoprotein (pp65), respectively, is in development to prevent cytomegalovirus infection.

METHODS

HB-101 was tested in cytomegalovirus-naive, healthy adults in a randomized, double-blind, placebo-controlled, dose-escalation Phase I trial. Fifty-four subjects received low, medium, or high dose of HB-101 or placebo by intramuscular administration at Month 0, 1, and 3. Safety and immunogenicity were the respective primary and secondary endpoints. Subjects were followed for 12 months after the initial immunization.

RESULTS

Vaccination was associated with transient mild to moderate adverse events. HB-101 administration induced dose-dependent gB- and pp65-specific cellular responses, dominated by pp65-specific CD8 T cells, a high fraction of which were polyfunctional. Two administrations were sufficient to elicit dose-dependent gB-binding and cytomegalovirus-neutralizing antibodies (Abs). Cytomegalovirus-specific immune responses were boosted after each administration. Only 1 of 42 vaccine recipients mounted a transient LCMV vector-neutralizing Ab response.

CONCLUSIONS

HB-101 was well tolerated and induced cytomegalovirus-specific polyfunctional CD8 T-cell and neutralizing Ab responses in the majority of subjects. Lack of vector-neutralizing Ab responses should facilitate booster vaccinations. These results justify further clinical evaluation of this vaccine candidate.

Vectors based on modified vaccinia Ankara expressing influenza H5N1 hemagglutinin induce substantial cross-clade protective immunity

BACKGROUND

New highly pathogenic H5N1 influenza viruses are continuing to evolve with a potential threat for an influenza pandemic. So far, the H5N1 influenza viruses have not widely circulated in humans and therefore constitute a high risk for the non immune population. The aim of this study was to evaluate the cross-protective potential of the hemagglutinins of five H5N1 strains of divergent clades using a live attenuated modified vaccinia Ankara (MVA) vector vaccine.

METHODOLOGY/PRINCIPAL FINDINGS

The replication-deficient MVA virus was used to express influenza hemagglutinin (HA) proteins. Specifically, recombinant MVA viruses expressing the HA genes of the clade 1 virus A/Vietnam/1203/2004 (VN/1203), the clade 2.1.3 virus A/Indonesia/5/2005 (IN5/05), the clade 2.2 viruses A/turkey/Turkey/1/2005 (TT01/05) and A/chicken/Egypt/3/2006 (CE/06), and the clade 2.3.4 virus A/Anhui/1/2005 (AH1/05) were constructed. These experimental live vaccines were assessed in a lethal mouse model. Mice vaccinated with the VN/1203 hemagglutinin-expressing MVA induced excellent protection against all the above mentioned clades. Also mice vaccinated with the IN5/05 HA expressing MVA induced substantial protection against homologous and heterologous AH1/05 challenge. After vaccination with the CE/06 HA expressing MVA, mice were fully protected against clade 2.2 challenge and partially protected against challenge of other clades. Mice vaccinated with AH1/05 HA expressing MVA vectors were only partially protected against homologous and heterologous challenge. The live vaccines induced substantial amounts of neutralizing antibodies, mainly directed against the homologous challenge virus, and high levels of HA-specific IFN-γ secreting CD4 and CD8 T-cells against epitopes conserved among the H5 clades and subclades.

CONCLUSIONS/SIGNIFICANCE

The highest level of cross-protection was induced by the HA derived from the VN/1203 strain, suggesting that pandemic H5 vaccines utilizing MVA vector technology, should be based on the VN/1203 hemagglutinin. Furthermore, the recombinant MVA-HA-VN, as characterized in the present study, would be a promising candidate for such a vaccine.

A whole virus pandemic influenza H1N1 vaccine is highly immunogenic and protective in active immunization and passive protection mouse models

The recent emergence and rapid spread of a novel swine-derived H1N1 influenza virus has resulted in the first influenza pandemic of this century. Monovalent vaccines have undergone preclinical and clinical development prior to initiation of mass immunization campaigns. We have carried out a series of immunogenicity and protection studies following active immunization of mice, which indicate that a whole virus, nonadjuvanted vaccine is immunogenic at low doses and protects against live virus challenge. The immunogenicity in this model was comparable to that of a whole virus H5N1 vaccine, which had previously been demonstrated to induce high levels of seroprotection in clinical studies. The efficacy of the H1N1 pandemic vaccine in protecting against live virus challenge was also seen to be equivalent to that of the H5N1 vaccine. The protective efficacy of the H1N1 vaccine was also confirmed using a severe combined immunodeficient (SCID) mouse model. It was demonstrated that mouse and guinea pig immune sera elicited following active H1N1 vaccination resulted in 100% protection of SCID mice following passive transfer of immune sera and lethal challenge. The immune responses to a whole virus pandemic H1N1 and a split seasonal H1N1 vaccine were also compared in this study. It was demonstrated that the whole virus vaccine induced a balanced Th-1 and Th-2 response in mice, whereas the split vaccine induced mainly a Th-2 response and only minimal levels of Th-1 responses. These data supported the initiation of clinical studies with the same low doses of whole virus vaccine that had previously been demonstrated to be immunogenic in clinical studies with a whole virus H5N1 vaccine.

Seasonal influenza vaccine elicits heterosubtypic immunity against H5N1 that can be further boosted by H5N1 vaccination

Recent findings indicate that seasonal influenza vaccination or infection of healthy humans may contribute to heterosubtypic immunity against new influenza A subtypes, such as H5N1. Here, we investigated whether seasonal influenza vaccination in a mouse model could induce any immunity against the H5N1 subtype. It could be demonstrated that, largely due to the H1N1 component strain A/NewCaledonia/20/99, parenteral immunization of mice with a trivalent seasonal influenza vaccine elicited heterosubtype H5-reactive antibodies able to confer partial protection against H5N1 influenza virus infection. Furthermore, the trivalent seasonal influenza vaccine was found to be compatible with a whole virus H5N1 vaccine in a heterologous prime-boost immunization regimen, achieving superior efficacy compared to a single immunization with an equivalent low-dose of the H5N1 vaccine.

[Right sided lower abdominal pain two weeks after delivery]

We report the CT imaging findings of a 33 year old patient who presented to the emergency department with increasing right lower abdominal pain and shivering. She delivered a healthy baby two weeks ago after induction in the 39th week of pregnancy due to a large fetus. Two days after delivery, sterilisation was performed. Clinically the primary differential diagnosis was appendicitis. However, computed tomography revealed thrombosis of the right ovarian vein. Consequently, management was altered appropriately with administration of antibiotics as well as a therapeutic dose of low molecular weight heparin.

Inhibition of HIV-1 infection in vitro by monoclonal antibodies to the complement receptor type 3 (CR3): an accessory role for CR3 during virus entry?

Adhesion molecules are known to contribute to infectivity of HIV-1. Here we tested whether the complement receptor type 3 (CR3, CD11b), an alpha(m)beta2 integrin, plays an accessory role in the infection process of HIV-1, because ICAM-1, a ligand of CR3, is present on the envelope of HIV-1. In addition, the viral transmembrane protein gp41 shares four regions of homology with the complement component C3, a further CR3 ligand. Infection of PBMCs with HIV-IIIB and primary isolates was partially inhibited by anti-CR3 antibodies. A peptide derived from the complement component C3, covering the CR3-binding site of C3 and sharing strong similarity to the immunosuppressive region of gp41, significantly reduced the HIV-1 titer in infection assays. Recombinant soluble gp41 (rsgp41) and the peptide covering the immunosuppressive domain of gp41 inhibited the rosetting of iC3b-coated sheep erythrocytes with U937 via complement receptors (CRs) with an efficiency comparable to monoclonal anti-CR antibodies. In addition, sub-populations of CD4 + and CD8 + T-cells isolated from HIV-infected individuals were found to upregulate CR3 as determined by FACS analysis and on the mRNA level. Since gp41 has been implicated in viral fusion, an interaction of its C3-homology region in gp41 or an interaction of ICAM on the surface of free virus with CRs might contribute to facilitate viral entry.

[Thrombolysis following myocardial infarct. European Secondary Prevention Study]

For evaluation of the management of patients with acute myocardial infarction, all cases of ten Zurich hospitals (278, 184 men and 94 women) in the period from 1 January to 31 March 1993 were analyzed retrospectively. 223 patients were released from hospital, 55 died. A follow-up was done 6 months after the patient's discharge by means of a questionnaires to the family doctor (return rate: 65.9%). 48.5% of patients were referred to hospital within the first 6 h. after onset of symptoms, 64% within the first 12 h. 28% (n = 76) of the patients received a thrombolytic therapy, of which 91% (n = 69) got streptokinase and 9% (n = 7) got tissue plasminogen activator. In 81% of the cases the thrombolytic therapy was done within the first hour in hospital, in accumulated 97% of the cases within two hours. In the age group under 65 years (39% of the patients, n = 109), 48 patients received thrombolysis (odds ratio [OR] = 1.0). In the age group between 65 and 74 years (24.5 % of the patients, n = 68), 19 patients received thrombolysis (OR: 0.49; 95% CI: 0.42-0.99; p < 0.05), and in the age group over 74 years (36.5% of the patients, n = 101), 9 patients were received thrombolysis (OR: 0.12; 95% CI: 0.05-0.28; p < 0.0001). 31% of the patients (n = 46) received a coronary angiography, 15% (n = 22) had coronary angioplasty, and 11% (n = 1) received coronary bypass surgery. There is evidence that there should be more importance attached to early hospitalization, if acute myocardial infarction is suspected. Thereby age alone should be considered as a contraindication for thrombolytic therapy. The issue of assumed underuse of thrombolytic therapy should be investigated all over Switzerland.

Ligation of the functional domain of complement receptor type 2 (CR2, CD21) is relevant for complex formation in T cell lines

We investigated the potential of CD21, the complement receptor type 2, to form receptor complexes with other membrane molecules on T cell lines. CD21 from T cell lines transformed with human T cell leukemia virus type I (MT2, HUT-102, C5.MJ, Mondi, and C91.PL) and T cell lines that were not virus transformed was analyzed by coprecipitation following cell lysis with digitonin. mAbs binding to functional and nonfunctional epitopes of CD21 and a polyclonal antiserum against its intracellular portion precipitated CD21, which was indistinguishable from CD21 on B cell lines. In contrast to B cells, where CD21 is complexed with CD19 and CD81 (target of anti-proliferative Ab 1) or, alternatively, with CD35 (CR1), no surface molecules could be coprecipitated with three of four mAbs from these T cell lines. Therefore, we assume that CD21 is not part of a preformed complex in T cell lines. OKB7, the only mAb directed against the functional C3d binding site, coprecipitated two proteins of 105 and 55 Mr with CD21 from MT2 and Mondi cells and from the T cell lines Jurkat E6-1 and SupT1. These bands were also recovered with CD21 precipitated from MT2 cells with C3d bound to Sepharose via the internal thioester, but were absent in CD21-expressing B cell lines. As C3d and OKB7 are functional ligands for B cells, we propose that upon ligation on T cells, CD21 associates with molecules of 105/55 Mr in the plasma membrane. Whether this is the first event of a signal delivered to the T cell is under current investigation.

Ligation of the functional domain of complement receptor type 2 (CR2, CD21) is relevant for complex formation in T cell lines

We investigated the potential of CD21, the complement receptor type 2, to form receptor complexes with other membrane molecules on T cell lines. CD21 from T cell lines transformed with human T cell leukemia virus type I (MT2, HUT-102, C5.MJ, Mondi, and C91.PL) and T cell lines that were not virus transformed was analyzed by coprecipitation following cell lysis with digitonin. mAbs binding to functional and nonfunctional epitopes of CD21 and a polyclonal antiserum against its intracellular portion precipitated CD21, which was indistinguishable from CD21 on B cell lines. In contrast to B cells, where CD21 is complexed with CD19 and CD81 (target of anti-proliferative Ab 1) or, alternatively, with CD35 (CR1), no surface molecules could be coprecipitated with three of four mAbs from these T cell lines. Therefore, we assume that CD21 is not part of a preformed complex in T cell lines. OKB7, the only mAb directed against the functional C3d binding site, coprecipitated two proteins of 105 and 55 Mr with CD21 from MT2 and Mondi cells and from the T cell lines Jurkat E6-1 and SupT1. These bands were also recovered with CD21 precipitated from MT2 cells with C3d bound to Sepharose via the internal thioester, but were absent in CD21-expressing B cell lines. As C3d and OKB7 are functional ligands for B cells, we propose that upon ligation on T cells, CD21 associates with molecules of 105/55 Mr in the plasma membrane. Whether this is the first event of a signal delivered to the T cell is under current investigation.

A general enhancement scheme in heteronuclear multidimensional NMR employing pulsed field gradients

General pulse sequence elements that achieve sensitivity-enhanced coherence transfer from a heteronucleus to protons of arbitrary multiplicity are introduced. The building blocks are derived from the sensitivity-enhancement scheme introduced by Cavanagh et al. ((1991) J. Magn. Reson., 91, 429-436), which was used in conjunction with gradient coherence selection by Kay et al. ((1992) J. Am. Chem. Soc., 114, 10663-10665), as well as from a multiple-pulse sequence effecting a heteronuclear planar coupling Hamiltonian. The building blocks are incorporated into heteronuclear correlation experiments, in conjunction with coherence selection by the formation of a heteronuclear gradient echo. This allows for efficient water suppression without the need for water presaturation. The methods are demonstrated in HSQC-type experiments on a sample of a decapeptide in H2O. The novel pulse sequence elements can be incorporated into multidimensional experiments.