Complete remission of mantle-cell non-Hodgkin lymphoma with a dendritic cell vaccine

Background. Persistence of measurable residual disease (MRD) in patients with acute myeloid leukemia (AML) remains a poor prognostic factor and unmet medical need. The allogeneic leukemia-derived dendritic cell vaccine, DCP-001, has shown in a phase I study to generate both humoral and cellular immune responses and is safe for clinical practice (van de Loosdrecht et al., Cancer Immunol. Immunother. 2018). In the current phase II study (Clintrials.gov: NCT03697707) we show the capability of DCP-001 to convert MRD positive patients to negative, leading to deeper remissions. Additionally, it is shown that DCP-001 induces immune responses, also specifically against tumor associated antigens known to be present in DCP-001 and relevant for AML. Methods. The current trial aims to enroll up to 20 AML -patients, ineligible for HSCT, who are in in first complete remission (CR1) but who are still MRD positive. MRD is assessed in the bone marrow through flow cytometry and/or qPCR (eg NPM1). Patients receive a primary vaccination regimen of 4 times 25.106or 50.106cells per vaccination, biweekly, followed by two booster vaccinations (10.106cells/vaccination) at week 14 and 18 after start of treatment. Primary endpoints of this trial are the safety and tolerability of the two vaccination schedules and the effect of vaccination on the MRD status. Additionally, cellular and humoral immune response induced by DCP-001 are evaluated in peripheral blood using several assay methods, including flow cytometry and IFN-ϒ ELISpot against known TAA's such as WT-1, RHAMM and PRAME. Results. Up to 15 July 2020, ten patients (age 41-76; 5 male, 5 female) have been enrolled and dosed within the study, completing the first dose cohort of 25.106cells/vaccination. All vaccinations were well tolerated and adverse events to the vaccine were limited to local injection site reactions such as redness, swelling and warmth (maximum grade 2). Three of the ten patient relapsed before the vaccination schedule was completed. Four patients could be evaluated for MRD; Two patients became MRD negative at the first timepoint after the initial vaccinations (week 14), and remained negative until end of active FU (week 32), two other patients remained in CR, but with MRD positivity. For the remaining three patients, to date, no MRD outcome is available yet but patients remain in CR (see swimmers plot for overview, Figure 1). Evaluation of the immune response before, during and after DCP-001 vaccination has only be performed in a small subset of three patients thus far. Of these patients one showed a clinical response becoming MRD negative after vaccination. In this patient we observed an increase in tumor specific functional T-cells assessed by IFNγ ELISPOT, either as a recall or primary response, as shown by the response observed to WT-1 (see for example Figure 2). These tumor associated antigens are known to be expressed by DCP-001 and included WT1, PRAME and RHAMM. Induction of specific memory CD8 and CD4 cells could be observed upon vaccination which might be related to the clinical response. Conclusion/discussion.Preliminary data from this ongoing study confirms that vaccination with DCP-001 is able to generate a tumor-specific immune response and may lead to potential tumor control. Two patients were actually converted from being MRD positive at start of vaccination to MRD negative during the study. These patients continue to be in complete remission for at least a year after vaccination. This study continues to enroll patients at a higher vaccine dose of 50.106cells per vaccination and additional data on induced immune responses and MRD status will be shown. Disclosures van de Loosdrecht: novartis: Honoraria; celgene: Honoraria. Wagner:Novartis: Membership on an entity's Board of Directors or advisory committees; Shire: Other: Travel grand; MSD: Membership on an entity's Board of Directors or advisory committees; Medac: Other: Travel grand; Kite/Gilead: Membership on an entity's Board of Directors or advisory committees. Platzbecker:Amgen: Honoraria, Research Funding; Janssen: Consultancy, Honoraria, Research Funding; BMS: Consultancy, Honoraria; Novartis: Consultancy, Honoraria, Research Funding; AbbVie: Consultancy, Honoraria; Takeda: Consultancy, Honoraria; Geron: Consultancy, Honoraria. Rovers:DCprime: Current Employment.

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Durable Responses and Survival in High Risk AML and MDS Patients Treated with an Allogeneic Leukemia-Derived Dendritic Cell Vaccine

Blood ◽

10.1182/blood-2019-127881 ◽

2019 ◽

Vol 134 (Supplement_1) ◽

pp. 1381-1381 ◽

Cited By ~ 1

Author(s):

Luca L.G. Janssen ◽

Theresia M. Westers ◽

Jeroen Rovers ◽

Peter Valk ◽

Jacqueline Cloos ◽

...

Keyword(s):

Clinical Trial ◽

Dendritic Cell ◽

High Risk ◽

Complete Remission ◽

Research Funding ◽

Medical Center ◽

Phase 1 ◽

Dendritic Cell Vaccine ◽

Cell Vaccine

Background. Maintenance of induced responses remains a significant unmet medical need in patients with acute myeloid leukemia (AML) or high risk myelodysplastic syndrome (MDS) not eligible for allogeneic hematopoietic stem cell transplantation (HSCT). The allogeneic leukemia-derived dendritic cell vaccine, DCP-001, has shown to generate both humoral and cellular immune responses and is safe for clinical practice (van de Loosdrecht et al., Cancer Immunol. Immunother. 2018). In this study we show additional data on long-term follow up and patient-related risk factors from the phase 1 study. Methods. AML- or MDS-patients (n=12), ineligible for HSCT, were included in a post-hoc clinical analysis of the DCP-001 phase I trial, receiving DCP-001 vaccination at the Amsterdam University Medical Center, VU University Medical Center, Amsterdam, the Netherlands (NCT01373515). All clinical data, including baseline characteristics as cytogenetics, pre-and post-vaccination treatment and morphologic blast counts in follow up, were retrospectively collected from corresponding patient files. Targeted next generation sequencing (NGS) gene panel data and cytogenetics were utilized to determine (cyto-)genetic risks following the European Leukemia Net (ELN) 2017 criteria. We defined 'response' as decreased or stable morphologic blast counts in bone marrow at day 126 (last day of official study evaluation) compared to study entry. Results. Seven out of twelve patients responded to treatment, the other patients showed progressive disease (data are summarized in table 1). The median relapse free survival (RFS) for the responding patients was 420 days (range 90-1849) and overall survival (OS) was 1090 days (90-2160); two patients died early in complete remission (CR) due to infection (respectively at 90 and 184 days). Notably, three of these patients were intermediate risk and four were poor risk patients based on the ELN risk classification for AML or Revised International Prognostic Scoring System (IPSS-R) for MDS. The median OS for the non-responders was 144 days (range 59-209). These five patients had relapsed or refractory disease at start of vaccination with detectable circulating peripheral blasts; four of them received additional azacitidine (AZA) therapy prior to vaccination. Moreover, they were vaccinated after induction and consolidation therapy with a median time between diagnosis and first vaccination of 611 days (219-2310) compared to 240 days (105-1398) for the seven responding patients. Of the latter, all were in complete remission (CR) (n=5) or had morphologic marrow blast counts <10% (n=2) at the start of vaccination. Two responders that progressed and two that relapsed after vaccination were treated with AZA, resulting in one complete remission and two partial responses (one non-evaluable due to sample failure), see figure 1. Conclusion/discussion. Clinical data of the phase 1 trial show that DCP-001 may prolong duration of remission or smoldering disease in intermediate and high risk AML or MDS patients. Response was associated with treatment by vaccination shortly after achieving CR. This should be taken into account in selection criteria of future vaccination studies. Hence, an international multi-center phase 2 study (ADVANCE II; NCT03697707) is currently being conducted to determine the effect of DCP-001 on measurable residual disease (MRD) in AML patients, aiming to convert them to a MRD negative state. Furthermore, we demonstrated that AZA can be applied as rescue therapy upon progression after vaccination. Disclosures Rovers: DCprime: Employment. Cloos:Daiicchi Sankyo: Speakers Bureau; Glycomimetics: Research Funding; Takeda: Research Funding; Novartis: Other: MRD assessments of clinical trials, Research Funding; Merus: Other: MRD assessment of a clinical trial , Research Funding; Genentech: Consultancy, Research Funding; Helsinn: Other: MRD assessment of a clinical trial; DCPrime: Other: MRD assessment of a clinical trial. de Gruijl:DCprime: Consultancy, Membership on an entity's Board of Directors or advisory committees.

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