A Model-Based Framework to Identify Optimal Administration Protocols for Immunotherapies in Castration-Resistance Prostate Cancer

Prostate cancer (PCa) is one of the most frequent cancer in male population. Androgen deprivation therapy is the first-line strategy for the metastatic stage of the disease, but, inevitably, PCa develops resistance to castration (CRPC), becoming incurable. In recent years, clinical trials are testing the efficacy of anti-CTLA4 on CRPC. However, this tumor seems to be resistant to immunotherapies that are very effective in other types of cancers, and, so far, only the dendritic cell vaccine sipuleucel-T has been approved. In this work, we employ a mathematical model of CRPC to determine the optimal administration protocol of ipilimumab, a particular anti-CTLA4, as single treatment or in combination with the sipuleucel-T, by considering both the effect on tumor population and the drug toxicity. To this end, we first introduce a dose-depending function of toxicity, estimated from experimental data, then we define two different optimization problems. We show the results obtained by imposing different constraints, and how these change by varying drug efficacy. Our results suggest administration of high-doses for a brief period, which is predicted to be more efficient than solutions with prolonged low-doses. The model also highlights a synergy between ipilimumab and sipuleucel-T, which leads to a better tumor control with lower doses of ipilimumab. Finally, tumor eradication is also conceivable, but it depends on patient-specific parameters.

Phase I Clinical Trial of an Autologous Dendritic Cell Vaccine Against HER2 Shows Safety and Preliminary Clinical Efficacy

BackgroundDespite recent advances, there is an urgent need for agents targeting HER2-expressing cancers other than breast cancer. We report a phase I study (NCT01730118) of a dendritic cell (DC) vaccine targeting HER2 in patients with metastatic cancer or bladder cancer at high risk of relapse.Patients and MethodsPart 1 of the study enrolled patients with HER2-expressing metastatic cancer that had progressed after at least standard treatment and patients who underwent definitive treatment for invasive bladder cancer with no evidence of disease at the time of enrollment. Part 2 enrolled patients with HER2-expressing metastatic cancer who had progressed after anti-HER2 therapy. The DC vaccines were prepared from autologous monocytes and transduced with an adenoviral vector expressing the extracellular and transmembrane domains of HER2 (AdHER2). A total of five doses were planned, and adverse events were recorded in patients who received at least one dose. Objective response was evaluated by unidimensional immune-related response criteria every 8 weeks in patients who received at least two doses. Humoral and cellular immunogenicity were assessed in patients who received more than three doses.ResultsA total of 33 patients were enrolled at four dose levels (5 × 106, 10 × 106, 20 × 106, and 40 × 106 DCs). Median follow-up duration was 36 weeks (4–124); 10 patients completed five doses. The main reason for going off-study was disease progression. The main adverse events attributable to the vaccine were injection-site reactions. No cardiac toxicity was noted. Seven of 21 evaluable patients (33.3%) demonstrated clinical benefit (1 complete response, 1 partial response, and 5 stable disease). After ≥3 doses, an antibody response was detected in 3 of 13 patients (23.1%), including patients with complete and partial responses. Lymphocytes from 10 of 11 patients (90.9%) showed induction of anti-HER2 responses measured by the production of at least one of interferon-gamma, granzyme B, or tumor necrosis factor-alpha, and there were multifunctional responses in 8 of 11 patients (72.7%).ConclusionsThe AdHER2 DC vaccine showed evidence of immunogenicity and preliminary clinical benefit in patients with HER2-expressing cancers, along with an excellent safety profile. It shows promise for further clinical applications, especially in combination regimens.

Characteristics and features of the formation of humoral immunity after immunization with Sputnik V and Vero Cell vaccines

The presented work contains an analysis of seroprevalence, tension, and duration of post-vaccination immunity to the SARS-CoV-2 coronavirus in the residents of the Republic of Belarus after immunization with two vaccine preparations available in the country: Sputnik V and Vero Cell.It was found that seroconversion after the injection of the Vero Cell vaccine occurred significantly later than after the Sputnik V vaccine (p < 0.001). Nevertheless, two-stage immunization with the vaccines provided a sufficiently high efficiency of the inoculated antibodies to the S protein of the COVID-19 pathogen: the proportion of seropositive persons reached 99.19 [96.89; 99.97] % for Sputnik V and 96.03 [90.81; 98.53] % for Vero Cell. The efficiency of antibody formation after immunization with the Vero Cell vaccine was lower in older persons (in the group > 65 years). The proportion of individuals with the highest IgG score for the SARS-CoV-2 S protein was higher after the Sputnik V administration compared to that in response to the Vero Cell vaccine (p < 0.05), and gradually decreased over time. However, no significant decrease in the level of seropositive individuals after 90 days from the start of immunization with the both vaccine preparations was detected. In COVID-19 survivors immunized with the Sputnik V vaccine, the quantitative indicators of post-vaccination antibodies reached their peak values after 1 dose of the vaccine. The obtained results complement the accumulated world science and practical information on the problem of the postvaccination immunity formation in the context of the use of different drugs against COVID-19.>< 0.001). Nevertheless, two-stage immunization with the vaccines provided a sufficiently high efficiency of the inoculated antibodies to the S protein of the COVID-19 pathogen: the proportion of seropositive persons reached 99.19 [96.89; 99.97] % for Sputnik V and 96.03 [90.81; 98.53] % for Vero Cell. The efficiency of antibody formation after immunization with the Vero Cell vaccine was lower in older persons (in the group > 65 years). The proportion of individuals with the highest IgG score for the SARS-CoV-2 S protein was higher after the Sputnik V administration compared to that in response to the Vero Cell vaccine (p < 0.05), and gradually decreased over time. However, no significant decrease in the level of seropositive individuals after 90 days from the start of immunization with the both vaccine preparations was detected. In COVID-19 survivors immunized with the Sputnik V vaccine, the quantitative indicators of post-vaccination antibodies reached their peak values after 1 dose of the vaccine.The obtained results complement the accumulated world science and practical information on the problem of the postvaccination immunity formation in the context of the use of different drugs against COVID-19.

A Personalized Neoantigen Vaccine in Combination with Platinum-Based Chemotherapy Induces a T-Cell Response Coinciding with a Complete Response in Endometrial Carcinoma

Endometrial cancer (EC) is a common gynecological malignancy and the fourth most common malignancy in European and North American women. Amongst EC, the advanced serous, p53-mutated, and pMMR subtypes have the highest risk of relapse despite optimal standard of care therapy. At present, there is no standard of care maintenance treatment to prevent relapse among these high-risk patients. Vaccines are a form of immunotherapy that can potentially increase the immunogenicity of pMMR, serous, and p53-mutated tumors to render them responsive to check point inhibitor-based immunotherapy. We demonstrate, for the first time, the feasibility of generating a personalized dendritic cell vaccine pulsed with peptide neoantigens in a patient with pMMR, p53-mutated, and serous endometrial adenocarcinoma (SEC). The personalized vaccine was administered in combination with systemic chemotherapy to treat an inoperable metastatic recurrence. This treatment association demonstrated the safety and immunogenicity of the personalized dendritic cell vaccine. Interestingly, a complete oncological response was obtained with respect to both radiological assessment and the tumor marker CA-125.

Evaluation of B-Cell Kinetics After Acellular Pertussis Vaccination in Four Cohorts of Different Age and Priming Background

Pertussis is a vaccine-preventable disease caused by the bacterium Bordetella pertussis. Over the past years, the incidence and mortality of pertussis increased significantly. A possible cause is the switch from whole cell to acellular pertussis vaccines, although other factors may also contribute. To develop future vaccines and improve current vaccination strategies, it is critical to understand factors influencing the generation of immunological memory. We applied high-dimensional flow cytometry to investigate changes in B cells in individuals of different ages and distinct priming backgrounds upon administration of an acellular pertussis booster vaccine. These findings were correlated to vaccine-specific plasma cells and serum Ig levels. Expansion and maturation of plasma cells 7 days post-vaccination was the most prominent cellular change in all age groups, and was most pronounced for more mature IgG1+ plasma cells. Cellular responses were stronger in individuals primed with whole cell vaccine than in individuals primed with acellular vaccine. Moreover, IgG1+ plasma cell expansion weakly correlated with Prn- and PT- specific serum IgG levels. Our study points at plasma cells as a potential early cellular marker of an immune response and contributes to understanding differences in immune responses between age groups and priming backgrounds.

Melanoma Stem Cell Vaccine Modified with IL-33 Induces Anti-Tumor Immunity by Activating CD8+T Cells

Background: Melanoma stem cells (MSCs)-based vaccine strategies have been a potent immunotherapeutic approach for melanoma treatment, which aimed at inducing specific anti-tumor immunity and targeting cancer stem-like cells. To boost anti-melanoma activity induced by B16F10 CD44+CD133+ MSCs (B16F10 MSCs) vaccine, we generated a novel vaccine expressing IL-33. Tumor growth and pulmonary metastasis were assessed to estimate the effectiveness of the vaccine. Methods: The antitumor effect of the vaccine was observed in this study. The mechanism of inducing anti-tumor immunity was detected by flow cytometric assays, cytotoxicity assays, and ELISA, including expression of CD8+T cells surface and intracellular molecules, the cytotoxic activity of splenocytes in the immunized mice and secretion of serum cytokines.Results: We found that MSCs vaccine expressing IL-33 significantly inhibited melanoma growth and reduced the lung melanoma nodules. Mechanistic investigations established that the vaccine-primed CD8+T cells could selectively target MSCs and confer anti-tumor immunity, which included promoting the proliferation of CD8+T cells, inhibiting the differentiated depletion of CD8+T cells in vivo, inducing the formation of memory CD8+T cells, and activating specific cytotoxic T lymphocyte (CTL) immune response. Conclusions: MSCs vaccine expressing IL-33 is able to initiate anti-tumor specific immune response by activating CD8+T cells.

Treatment with an Allogeneic Leukemia-Derived Dendritic Cell Vaccine in AML Patients Shows MRD Conversion and Improved Survival

Background. Persistence of measurable residual disease (MRD) is a poor prognostic factor and predicts relapse in acute myeloid leukemia (AML). In a phase I study, the allogeneic leukemia-derived dendritic cell vaccine, DCP-001, has shown safety and humoral and cellular immune responses (A.A. van de Loosdrecht, et al. Cancer Immunol. Immunother. 2018;67:1505). In the current phase II study, (Clintrials.gov: NCT03697707) we report on progress and evaluation of MRD conversion, as primary endpoint, relapse free and overall survival. Methods. AML-patients, ineligible at screening for HSCT, who are in first complete remission (CR1) but with MRD receive 4 biweekly doses of 25e6 or 50e6 cells per vaccination (cells/vc) followed by 2 doses of 10e6 cells/vc as boosts at week 14 and 18. MRD is assessed at 4 timepoints (baseline, week 14, 20 and 32) by flow cytometry and/or molecular analyses. Primary endpoints are the effect of vaccination on MRD status and safety and tolerability of the two vaccination schedules. Secondary endpoints include relapse free, overall survival and immunological response evaluation. Results. As of 28 th July 2021, 19 patients have been enrolled, of which 10 patients have been given at least 4 vaccinations with 25e6 cells/vc and 9 with 50e6 cells/vc. No serious adverse events (AE) or severe AE (grade 3 or higher) related to DCP-001 have been reported. AE's related to DCP-001 are mainly injection site reactions, occurring within 48 hours after intradermal administration. In the 25e6 cells/vc cohort all patients have completed the treatment phase up to week 32, allowing full assessment of MRD response. Three patients have converted to MRD negative, 4 patients relapsed (followed by HSCT for 1 patient), 3 patients remained MRD positive, of which 2 patients underwent HSCT immediately after completion of the full dosing schedule. In this cohort 2 patients eventually died during follow up. Treatment is still ongoing in the 50e6 dose cohort, with thus far one additional MRD conversion reported and two relapses, 3 patients with stable MRD levels, and 3 have no MRD data available yet. Median follow-up of patients in the 25e6 cells/vc cohort was 288 days (range 148 - 546). Median RFS and OS have not yet been reached, but estimated RFS and OS at 12 months is calculated at 57% and 79%, respectively (Figure 1). MRD converted patients after DCP-001 vaccination, showed improved survival, compared to patients without MRD conversion (Figure 2). All 4 patients who converted to MRD negative are still in CR and alive (FU median 423.5 days (range 140 - 546). Immunological monitoring of patients is currently being performed. As previously reported (abstract #168, ASH2020), 3 of 4 evaluable patients show at least 1 or more responses against tumor-associated antigens known to be present in DCP-001 in IFNy ELISPOT assay. Conclusion/discussion. Four patients have shown MRD conversion (3 in the 25e6 dose cohort, and 1 in the 50e6 dose cohort). Six patients remained in complete remission with stable or declining levels of MRD, 6 patients relapsed and for 3 patients no MRD data is available yet. Median RFS and OS have not yet been reached. MRD conversion showed improved relapse free and overall survival. Treatment with DCP-001 is very well tolerated, with limited side effects mainly related to intradermal administration. Immunological analyses for specific tumor-associated antigen responses and general immune profiling are currently being performed. Preliminary data from this study shows that the relapse vaccine DCP-001 is a promising treatment for patients with AML in complete remission but with residual disease aiming to deepen responses and prolong survival. Its excellent safety profile allows for future combination therapy. Figure 1 Figure 1. Disclosures Van de Loosdrecht: Novartis: Consultancy; Alexion: Consultancy; Roche: Consultancy; Amgen: Consultancy; Celgene: Consultancy, Research Funding. Cloos: Takeda: Research Funding; Novartis: Consultancy, Other, Research Funding; Navigate: Patents & Royalties; Merus: Other, Research Funding; Janssen: Research Funding; Helsinn: Other; Genentech: Research Funding; DC-One: Other, Research Funding; Astellas: Speakers Bureau. Platzbecker: AbbVie: Honoraria; Janssen: Honoraria; Novartis: Honoraria; Celgene/BMS: Honoraria; Geron: Honoraria; Takeda: Honoraria. Holderried: Gilead Sciences: Consultancy, Membership on an entity's Board of Directors or advisory committees; Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees; Amgen: Speakers Bureau; MSD: Speakers Bureau; GSK: Consultancy, Membership on an entity's Board of Directors or advisory committees; Celgene: Consultancy, Membership on an entity's Board of Directors or advisory committees; Sanofi: Consultancy, Membership on an entity's Board of Directors or advisory committees; Jazz Pharmaceuticals: Consultancy, Membership on an entity's Board of Directors or advisory committees; Therakos: Other: Travel support; Abbvie: Other: Travel support; Medac: Other: Travel support; Eurocept Pharmaceuticals: Other: Travel support; Janssen: Other: Travel support; Daiichi Sankyo: Other: travel support. Giagounidis: Novartis: Membership on an entity's Board of Directors or advisory committees; Amgen: Membership on an entity's Board of Directors or advisory committees. van Zeeburg: Immunicum AB: Current Employment; Kiadis: Ended employment in the past 24 months. Rovers: Immunicum AB: Current Employment. Gjertsen: KinN Therapeutics: Current holder of stock options in a privately-held company; Alden Cancer Therapy: Current holder of stock options in a privately-held company; Pfizer Inc.: Consultancy; BerGenBio: Consultancy; Novartis: Consultancy.