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We report a Leishmania infantum reactivation in an immunocompetent patient manifesting as visceral leishmaniasis with secondary IgA nephropathy nine years after an initial episode of mucosal leishmaniasis, which had been treated with liposomal amphotericin B.

Patients with new-onset malignant spinal lesions often have an urgent need for local spine intervention and systemic therapy. For optimal management, it is crucial to diagnose the underlying disease as quickly and reliably as possible. The aim of our current study was to determine the feasibility, sensitivity, specificity, and diagnostic certainty of complementary cytological evaluation of spinal lesions suspected of malignancy. In 44 patients, we performed histopathological biopsies and in parallel cytologic preparations from the malignant site. Cytological smears were prepared and stained for May-Grunwald and Giemsa. Bone biopsies were histopathologically analyzed according to the existing standard-of-care practices. In 42 of 44 cases (95%), a cytological sample was successfully obtained. In 40 cases (95.2%, Cohen’s kappa: 0.77), the cytological diagnosis agreed with the histological diagnosis regarding the identification of a malignant lesion. This resulted in a sensitivity of 97% and a specificity of 80% as well as a diagnostic safety of 95%. Cytological analysis in the context of spinal surgery proved sufficient to establish a diagnosis of malignancy or its exclusion, expanding the existing diagnostic spectrum. Furthermore, implementation of this process as a routine clinical diagnostic might shorten the time to diagnosis and improve the treatment of this vulnerable patient group.

Background: Progression of chronic myeloid leukemia (CML) is frequently accompanied by cytogenetic evolution, with an extra copy of the Philadelphia chromosome, trisomy 8 and 19, and isochromosome (17p) commonly detected. Translocations involving 11q23 chromosomal region have been rarely reported in CML. The few reported patients with blast crisis (BC) of CML carrying an 11q rearrangement have insufficient responses to tyrosine kinase inhibitors (TKIs) and possess a poor prognosis. Case report: We report the case of a 30-year-old man with CML who had a fulminant myeloid BC 4 months after initiation of first-line therapy with the TKI dasatinib, despite showing an optimal response at the 3-month timepoint. Despite cytoreductive therapy with hydroxyurea and 3rd-generation TKI ponatinib, the patient died within 10 days after the diagnosis of BC. Cytogenetic analyses revealed additional genetic aberrations including trisomy 8 and t(9;11)(p21;q23) involving the mixed lineage leukemia ( MLL) gene. Conclusion: The presence of 11q23 rearrangements in the relapse clone in BC of CML most likely accounts for the adverse clinical outcome. Thus, in the case of rapid and unexpected BC, the presence of 11q rearrangements should be tested together with other additional chromosomal alterations, and immediate addition of chemotherapy to the TKIs should be evaluated.

Background: High-risk (HR) multiple myeloma (MM) has an impaired prognostic outcome. Addition of anti-CD38 monoclonal antibodies to standard-of-care regimens improved response rates and depth of response. Here, we report a prespecified interim analysis (IA) following induction therapy with the quadruplet regimen isatuximab, carfilzomib, lenalidomide and dexamethasone (Isa-KRd) in newly diagnosed (ND) HR MM patients (pts) in the phase II multicentric GMMG-CONCEPT trial (NCT03104842). Methods: 153 pts with HR NDMM were enrolled into the trial, the IA reports on the first 50 pts evaluable for IA. Pts receive Isa-KRd in induction, consolidation and Isa-KR maintenance. Transplant eligible pts undergo high-dose therapy. This IA reports on overall response rates (ORR) during induction. Findings: 50 pts were included in the IA population for ORR. HR MM was defined by del17p in 52%, t(4;14) in 38%, t(14;16) in 12% and > 3 copies 1q21 in 42% and ISS stage 2/3 disease. 46/50 pts completed induction treatment. ORR was 100%, with 5 pts (10·0%) showing partial response (PR), 22 (44·0%; including 4 in arm B) very good partial response (VGPR) and 23 (46·0%) complete response (CR). Hematologic grade 3/4 treatment-emergent adverse events (≥ 10%) were neutropenia (34·0%), leukopenia (26·0%) and thrombocytopenia (14·0%). Main non-hematologic toxicities grade 3/4 were hypertension (12·0%) and infection (8·0%). Interpretation: We report for the first time on a trial investigating Isa-KRd quadruplet treatment in solely HR NDMM. Isa-KRd induction induces rapid and deep responses. The overall safety profile is consistent with previous reports. Trial Registration: The trial is registered at clinicaltrials.gov (NCT03104842). Funding Statement: Study drug and financial support by Amgen, Celgene-BMS and Sanofi. Declaration of Interests: Dr. Leypoldt reports grants and non-financial support from Celgene-BMS, grants and non-financial support from Sanofi, grants and non-financial support from Amgen, during the conduct of the study; non-financial support from GSK, non-financial support from Abbvie, outside the submitted work; Dr. Asemissen has nothing to disclose. Dr. Besemer has nothing to disclose. Dr. Hanel reports personal fees from Celgene, personal fees from Novartis, personal fees from Takeda, personal fees from Amgen, during the conduct of the study; Dr. Blau has nothing to disclose. Dr. Gorner has nothing to disclose. Dr. Ko has nothing to disclose. Dr. Reinhardt reports personal fees from Abbvie, grants from Gilead, personal fees from Merck, other from CDL Therapeutics GmbH, outside the submitted work; Dr. Staib reports grants, personal fees, non-financial support and other from Abbvie, grants, personal fees, non-financial support and other from Amgen, grants, personal fees, non-financial support and other from Celgene, grants, personal fees, non-financial support and other from Janssen-Cilag, grants, personal fees, non-financial support and other from Novartis, grants, personal fees, non-financial support and other from Gilead, grants, personal fees, non-financial support and other from Pfizer, grants, personal fees, non-financial support and other from Roche, outside the submitted work; Dr. Mann has nothing to disclose. Dr. Lutz has nothing to disclose. Dr. Munder reports personal fees and non-financial support from Janssen, personal fees and non-financial support from Amgen, grants from Incyte, personal fees and non-financial support from BMS, personal fees from Abbvie, personal fees from Sanofi, personal fees from GSK, personal fees from Takeda, outside the submitted work; Dr. Graeven reports personal fees from Amgen, personal fees and non-financial support from Boehringer Ingelheim, personal fees from Daichi Sankyo, personal fees from Servier, personal fees from Celgene, personal fees from Astra Zeneca, personal fees from Johnson Johnson, non-financial support from Merck, personal fees from MSD, personal fees from BMS, during the conduct of the study; Dr. Peceny reports grants and personal fees from Sanofi Genzyme, grants from Novartis, grants from DRK Blutspendedienst NSTOB, grants from Boehringer Ingelheim Pharma GmbH & Co KG, grants from Celgene, outside the submitted work; Dr. Salwender reports personal fees from Bristol-Myers Squibb/Celgene, personal fees from Janssen Cilag, personal fees from Glaxo Smith Kline, personal fees from Oncopeptides, personal fees from Takeda, personal fees from Sanofi, personal fees from AbbVie, personal fees from Amgen, outside the submitted work; Dr. Jauch has nothing to disclose. Dr. Zago has nothing to disclose. Axel Benner has nothing to disclose. Dr. Tichy has nothing to disclose. Dr. Bokemeyer reports personal fees from Sanofi Aventis, personal fees from Merck KgA, personal fees from Bristol-Myers Squibb, personal fees from Merck Sharp & Dohme, personal fees from Lilly Imclone, personal fees from Bayer Healthcare, personal fees from GSO Contract research, personal fees from AOK-Rheinland-Hamburg, personal fees from Novartis, outside the submitted work; Dr. Goldschmidt reports grants, personal fees, non-financial support and other from Amgen, grants, personal fees, non-financial support and other from BMS, grants, personal fees, non-financial support and other from Celgene, grants, personal fees, and other from Chugai, grants, personal fees, non-financial support and other from Janssen, grants, personal fees, non-financial support and other from Sanofi, other from Incyte, other from Molecular Partners, other from Merck Sharp and Dohme (MSD), other from Mundipharma, grants, personal fees, non-financial support and other from Takeda, personal fees and other from Novartis, personal fees from Adaptive Biotechnology, personal fees from GlaxoSmithKline (GSK), outside the submitted work. Dr. Weisel reports grants from AMGEN, grants from Celgene, grants from Sanofi, during the conduct of the study; grants, personal fees and non-financial support from Amgen, personal fees and non-financial support from BMS, grants, personal fees and non-financial support from Celgene, personal fees from Adaptive Biotech, grants, personal fees and non-financial support from Janssen, personal fees and non-financial support from GSK, personal fees from Karyopharm, grants, personal fees and non-financial support from Sanofi, personal fees and non-financial support from Takeda, personal fees from Oncopeptides, personal fees from Roche, outside the submitted work. Ethics Approval Statement: All patients provided written informed consent. The trial was approved by the competent authorities and the Tuebingen University Ethics Committee.

Background: In newly-diagnosed multiple myeloma (NDMM), lenalidomide/bortezomib/dexamethasone (RVd) is one of the most widely used combination regimens. Anti-CD38 monoclonal antibodies (CD38-moAb) increase efficacy when added to standard-of-care regimens. Here we present the first primary endpoint of the randomized, open-label, multicenter, phase III GMMG-HD7 trial, comparing RVd without (arm IA) or with the CD38-moAb isatuximab (Isa, arm IB) with regard to the rate of minimal residual disease (MRD) negativity after induction therapy in patients with transplant-eligible NDMM. Patients and Methods: Patients with transplant-eligible NDMM at 67 sites in Germany were equally randomized to receive three 42-day cycles of RVd (lenalidomide 25 mg/d p.o., d1-14 and d22-35; bortezomib 1.3 mg/m 2 s.c. d1, 4, 8, 11, 22, 25, 29, 32; dexamethasone 20 mg/d d1-2, 4-5, 8-9, 11-12, 15, 22-23, 25-26, 29-30, 32-33) in both arms. Isa was added to arm IB only (10 mg/kg i.v., cycle 1: d 1, 8, 15, 22, 29; cycles 2-3: d 1, 15, 29). Randomization for induction was stratified according to revised International Staging System (R-ISS). Primary endpoint of the trial was MRD negativity assessed by next-generation flow (NGF, cut off 1x10 -5) after induction. Secondary endpoints included rates of complete response (CR) after induction and safety. Data cut-off for the present analysis was April 2021. Results: Between 10/2018 and 09/2020, 662 patients were included in the trial. 660 patients were eligible for intention-to-treat analysis and 658 patients started induction (RVd: 329/328 and Isa-RVd: 331/330). Median age was 58 (range 26-70) years and baseline characteristics were well balanced between treatment arms. On induction, 35 (10.6%) and 18 (5.4%) patients discontinued treatment in the RVd vs. Isa-RVd arms (p=0.02). Among these, 8 (2.4%, RVd) vs. 7 (2.1%, Isa-RVd) patients discontinued induction due to adverse events (AE). 293 (89.1%) vs. 312 (94.3%) patients in the RVd vs. Isa-RVd arms continued further study treatment after induction. MRD negativity rates after induction were 35.6% vs. 50.1% (odds ratio [OR]=1.83, 95% confidence interval [95% CI]: 1.34-2.51, p At least one AE (grade ≥3) on induction occurred in 61.3% (RVd) and 63.6% (Isa-RVd) of patients (p=0.57). Most common AE (grade ≥3) by system organ class (SOC) for RVd vs. Isa-RVd were: "investigations": 23.5% vs. 23.9% (p=0.93), "blood and lymphatic system disorders": 16.8% vs. 25.8% (p=0.006), "infections and infestations": 10.4% vs. 13.0% (p=0.33) and "nervous system disorders": 10.1% vs. 8.5% (p=0.50). Rates of serious AE (SAE, any grade) on induction were similar between RVd and Isa-RVd (36.3% vs. 34.8%, p=0.75). Eight (RVd) and four (Isa-RVd) patients died during induction. Conclusions: The GMMG-HD7 trial met its primary endpoint. To the best of our knowledge this is the first phase III trial to demonstrate superiority of MRD negativity rates after induction by adding a CD38-moAb to RVd. There were no increased rates of SAE or early discontinuation in patients treated with Isa-RVd compared to RVd. The trial is ongoing, including analyses post autologous transplantation, which is followed by a second randomization to compare the efficacy of the addition of Isa to lenalidomide maintenance. Disclosures Goldschmidt: Takeda: Consultancy, Research Funding; Sanofi: Consultancy, Honoraria, Other: Grants and/or Provision of Investigational Medicinal Product, Research Funding; Adaptive Biotechnology: Consultancy; Incyte: Research Funding; GSK: Honoraria; Chugai: Honoraria, Other: Grants and/or Provision of Investigational Medicinal Product, Research Funding; Celgene: Consultancy, Honoraria, Other: Grants and/or Provision of Investigational Medicinal Product, Research Funding; BMS: Consultancy, Honoraria, Other: Grants and/or Provision of Investigational Medicinal Product, Research Funding; Janssen: Consultancy, Honoraria, Other: Grants and/or Provision of Investigational Medicinal Product, Research Funding; Johns Hopkins University: Other: Grant; Molecular Partners: Research Funding; MSD: Research Funding; Mundipharma: Research Funding; Dietmar-Hopp-Foundation: Other: Grant; Novartis: Honoraria, Research Funding; Amgen: Consultancy, Honoraria, Other: Grants and/or Provision of Investigational Medicinal Product, Research Funding. Mai: Celgene / BMS: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: travel accommodations and expenses, Research Funding; Glaxo Smith Kline: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: travel accommodations and expenses, Research Funding; Takeda: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: travel accommodations and expenses, Research Funding; Janssen-Cilag: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: travel accommodations and expenses, Research Funding. Fenk: Takeda: Honoraria; GSK: Honoraria; Amgen: Honoraria; Janssen: Honoraria; BMS/Celgene: Honoraria. Besemer: Takeda: Honoraria; Janssen: Honoraria; GSK: Honoraria. Dürig: Janssen: Membership on an entity's Board of Directors or advisory committees, Other: Travel Support, Speakers Bureau; Celgene: Membership on an entity's Board of Directors or advisory committees, Other: Travel Support, Speakers Bureau; Takeda: Membership on an entity's Board of Directors or advisory committees; BMS: Membership on an entity's Board of Directors or advisory committees. Schroers: BMS/Celgene: Consultancy, Honoraria; Janssen: Consultancy, Honoraria; GSK: Consultancy, Honoraria; Takeda: Honoraria. Metzler: Takeda: Consultancy; BMS: Consultancy; GSK: Consultancy; Amgen: Consultancy; Janssen: Consultancy; AstraZeneca: Consultancy; Pfizer: Consultancy; Sanofi: Consultancy. Haenel: Takeda: Consultancy, Honoraria; Jazz: Consultancy, Honoraria; GSK: Consultancy; Bayer Vital: Honoraria; Roche: Consultancy, Honoraria; Novartis: Consultancy, Honoraria; Amgen: Consultancy; Celgene: Consultancy, Honoraria. Mann: Cellgene: Consultancy. Asemissen: GSK: Honoraria; Pfizer: Honoraria; Celgene BMS: Honoraria. Heilmeier: Sanofi-Aventis Dtld. GmbH: Consultancy. Kriegsmann: Sanofi: Honoraria. Weinhold: Sanofi: Honoraria. Holderried: Amgen: Speakers Bureau; GSK: Consultancy, Membership on an entity's Board of Directors or advisory committees; Eurocept Pharmaceuticals: Other: Travel support; MSD: Speakers Bureau; Gilead Sciences: Consultancy, Membership on an entity's Board of Directors or advisory committees; Abbvie: Other: Travel support; Sanofi: 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; Celgene: Consultancy, Membership on an entity's Board of Directors or advisory committees; Janssen: Other: Travel support; Therakos: Other: Travel support; Daiichi Sankyo: Other: travel support; Medac: Other: Travel support; Jazz Pharmaceuticals: Consultancy, Membership on an entity's Board of Directors or advisory committees. Trautmann-Grill: Sanofi: Consultancy, Honoraria; Takeda: Consultancy, Honoraria; Janssen: Consultancy, Honoraria; GSK: Consultancy, Honoraria. Gezer: Amgen: Consultancy, Other: Invited Speaker; Takeda: Consultancy, Other: Invited Speaker; BMS: Consultancy, Other: Invited Speaker; Celgene: Consultancy, Other: Invited Speaker. Khandanpour: GSK: Honoraria; Takeda: Honoraria; Janssen: Honoraria; AstraZeneca: Honoraria, Research Funding; Pfizer: Honoraria; Sanofi: Honoraria, Research Funding; BMS/Celgene: Honoraria. Knauf: Amgen: Honoraria; Abbvie: Honoraria; Beigene: Consultancy, Honoraria; BMS: Honoraria; Celgene: Honoraria; Janssen: Consultancy, Honoraria; Sanofi: Honoraria; AstraZeneca: Consultancy, Honoraria. Munder: GSK: Consultancy; Amgen: Honoraria; Sanofi: Consultancy; Takeda: Consultancy, Honoraria; Abbvie: Consultancy; BMS: Consultancy, Honoraria; Janssen: Consultancy, Honoraria; Incyte: Research Funding. Hoffmann: Sanofi-Aventis: Consultancy. Raab: Roche: Consultancy; GSK: Honoraria, Membership on an entity's Board of Directors or advisory committees; Novartis: Membership on an entity's Board of Directors or advisory committees, Research Funding; Celgene: Membership on an entity's Board of Directors or advisory committees; Sanofi: Membership on an entity's Board of Directors or advisory committees, Research Funding; Abbvie: Consultancy, Honoraria; Janssen: Membership on an entity's Board of Directors or advisory committees; BMS: Consultancy, Membership on an entity's Board of Directors or advisory committees; Amgen: Consultancy, Membership on an entity's Board of Directors or advisory committees. Salwender: GlaxoSmithKline: Honoraria, Other: TRAVEL, ACCOMMODATIONS, EXPENSES; Sanofi: Honoraria, Other: TRAVEL, ACCOMMODATIONS, EXPENSES; Chugai: Honoraria; Oncopeptides: Honoraria; Takeda: Honoraria; Amgen: Honoraria, Other: TRAVEL, ACCOMMODATIONS, EXPENSES; AbbVie: Honoraria, Other: TRAVEL, ACCOMMODATIONS, EXPENSES; Janssen-Cilag: Honoraria, Other: TRAVEL, ACCOMMODATIONS, EXPENSES; Bristol-Myers Squibb/Celgene: Honoraria, Other: TRAVEL, ACCOMMODATIONS, EXPENSES; Pfizer: Honoraria. Weisel: Adaptive Biotechnologies: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Celgene: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Bristol Myers Squibb: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Takeda: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Amgen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Sanofi: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Karyopharm: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Roche: Honoraria; Janssen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; GSK: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Oncopeptides: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Abbvie: Consultancy; Novartis: Honoraria; Pfizer: Honoraria. OffLabel Disclosure: Isatuximab prior to ASCT in NDMM

Cancer immunotherapy with antibodies targeting immune checkpoints, such as programmed cell death protein 1 (PD-1), shows encouraging results, but reliable biomarkers predicting response to this costly and potentially toxic treatment approach are still lacking. To explore an immune signature predictive for response, we performed liquid biopsy immunoprofiling in 18 cancer patients undergoing PD-1 inhibition before and shortly after initiation of treatment by multicolor flow cytometry and next-generation T- and B-cell immunosequencing (TCRs/IGH). Findings were correlated with clinical outcomes. We found almost complete saturation of surface PD-1 on all T-cell subsets after the first dose of the antibody. Both T- and B-cell compartments quantitatively expanded during treatment. These expansions were mainly driven by an increase in the activated T-cell compartments, as well as of naive B- and plasma cells. Deep immunosequencing revealed a clear diversification pattern of the clonal T-cell space indicative of antigenic selection in 47% of patients, while the remaining patients showed stable repertoires. 43% of the patients with a diversification pattern showed disease control in response to the PD-1 inhibitor. No disease stabilizations were observed without clonal T-cell space diversification. Our data show for the first time a clear impact of PD-1 targeting not only on circulating T-cells, but also on B-lineage cells, shedding light on the complexity of the anti-tumor immune response. Liquid biopsy T-cell next-generation immunosequencing should be prospectively evaluated as part of a composite response prediction biomarker panel in the context of clinical studies.

8508 Background: High-risk (HR) multiple myeloma (MM) still has a significant impaired prognostic outcome. Addition of CD38 monoclonal antibodies to standard-of-care regimens significantly improved response rates and depth of response in newly diagnosed (ND) and relapsed/refractory MM patients (pts). Here, we report the prespecified end of induction interim analysis (IA) of the investigator-initiated GMMG-CONCEPT trial (NCT03104842), evaluating the quadruplet regimen isatuximab plus carfilzomib, lenalidomide and dexamethasone (Isa-KRd) in HR NDMM pts. Methods: 153 pts with HR NDMM are planned to be included into the trial. HR MM is defined by the presence of del17p or t(4;14) or t(14;16) or > 3 copies 1q21 and ISS 2 or 3 stage disease. Pts receive 6 cycles of Isa-KRd induction, 4 cycles of Isa-KRd consolidation and Isa-KR maintenance. Transplant eligible pts (arm A) undergo high-dose therapy. Transplant ineligible pts (arm B) receive 2 additional cycles of Isa-KRd induction. The primary endpoint is MRD negativity measured by next-generation flow after consolidation. This IA reports on overall response rates (ORR) after induction. Additional MRD analysis will be presented. Results: 50 pts (46 arm A, 4 arm B) were included in the IA population for ORR. HR MM was defined by del17p in 52%, t(4;14) in 38%, t(14;16) in 12% and > 3 copies 1q21 in 42%. 39/46 pts in arm A and 4/4 pts in arm B completed induction treatment. ORR was 100%, with 5 pts (10.0%) showing partial response (PR), 22 (44.0%; including 4 in arm B) very good partial response (VGPR) and 23 (46.0 %) complete response (CR). Median stem cell yield was 6.6 × 106CD34+ cells/kg. Grade 3/4 treatment-emergent adverse events (≥ 10%) with Isa-KRd included neutropenia (34.0%), leukopenia (26.0%) and thrombocytopenia (14.0%). Main non-hematologic toxicities grade 3/4 were hypertension (12.0%) and infection (8.0%). Conclusions: To the best of our knowledge, we report for the first time on a trial investigating solely HR NDMM and Isa-KRd quadruplet treatment. Isa-KRd induction induces deep responses in HR MM pts. The overall safety profile of Isa-KRd is expected and consistent with previous reports. The study is ongoing, with pts continuing to be included. Clinical trial information: 03104842 .

In myelodysplastic syndromes with a partial deletion of the long arm of chromosome 5, del(5q), lenalidomide is believed to reverse anergic T-cell immunity in the bone marrow resulting in suppression of the del(5q) clone. In this study we used next-generation sequencing of immunoglobulin heavy chain (IGH) and T-cell receptor beta (TRB) rearrangements in bone marrow-residing and peripheral blood-circulating lymphocytes of patients with del(5q) myelodysplastic syndromes to assess the immune architecture and track adaptive immune responses during treatment with lenalidomide. The baseline bone marrow B-cell space in patients was comparable to that of age-matched healthy controls in terms of gene usage and IGH clonality, but showed a higher percentage of hypermutated IGH sequences, indicating an expanded number of antigen-experienced B lineage cells. Bone marrow B lineage clonality decreased significantly and hypermutated IGH clones normalized upon lenalidomide treatment, well in line with the proliferative effect on healthy antigen-inexperienced B-cell precursors previously described for this drug. The T-cell space in bone marrow of patients with del(5q) myelodysplastic syndromes showed higher TRB clonality compared to that of healthy controls. Upon lenalidomide treatment, myelodysplastic syndrome-specific T-cell clusters with low to medium spontaneous generation probabilities emerged; these clusters were shared across patients, indicating a common antigen-driven T-cell response pattern. Hence, we observed B lineage diversification and generation of new, antigen-dependent T-cell clusters, compatible with a model of adaptive immunity induced against the del(5q) clone by lenalidomide. Overall, this supports the concept that lenalidomide not only alters the functional T-cell state, but also the composition of the T- and B-cell repertoires in del(5q) myelodysplastic syndromes.

[Figure][1] A 32-year-old man presented with skin lesions, leukocytosis (white blood cells, 162 × 109/L), thrombocytopenia (34 × 109/L), and elevated lactate dehydrogenase (1000 U/L). The blood film was consistent with chronic myelogenous leukemia (CML) with 3% “normal” blasts and a

Cancer immunotherapy with antibodies targeting immune checkpoints, such as programmed cell death protein 1 (PD-1), shows encouraging results, but reliable biomarkers predicting response to this costly and potentially toxic treatment approach are still lacking. To explore an immune signature predictive for response, we performed liquid biopsy immunoprofiling in 18 cancer patients undergoing PD-1 inhibition before and shortly after initiation of treatment by multicolor flow cytometry and next-generation T- and B-cell immunosequencing (TCRß/IGH). Findings were correlated with clinical outcomes. We found almost complete saturation of surface PD-1 on all T-cell subsets after the first dose of the antibody. Both T- and B-cell compartments quantitatively expanded during treatment. These expansions were mainly driven by an increase in the activated T-cell compartments, as well as of naïve B- and plasma cells. Deep immunosequencing revealed a clear diversification pattern of the clonal T-cell space indicative of antigenic selection in 47% of patients, while the remaining patients showed stable repertoires. 43% of the patients with a diversification pattern showed disease control in response to the PD-1 inhibitor. No disease stabilizations were observed without clonal T-cell space diversification. Our data show for the first time a clear impact of PD-1 targeting not only on circulating T-cells, but also on B-lineage cells, shedding light on the complexity of the anti-tumor immune response. Liquid biopsy T-cell next-generation immunosequencing should be prospectively evaluated as part of a composite response prediction biomarker panel in the context of clinical studies.

Background Tyrosine kinase inhibitors (TKI) such as sorafenib have substantially improved the prognosis of metastatic renal cell carcinoma (mRCC) patients, but long-term remissions have only been reached with immunotherapy. Sequencing or combining TKI treatment with immunotherapy may represent an attractive therapeutic concept. However, in vitro data have shown that TKI may not only affect tumour cells, but also inhibit signalling in immune effector cells. Therefore, we asked whether sorafenib had an influence on peripheral immune effector cells in a cohort of 35 mRCC patients receiving sorafenib treatment. Methods Peripheral blood (pB) samples were analysed at baseline and after 8 weeks of treatment. IL-10 and TGF-s mRNA levels were quantified by RT-PCR; regulatory T cell (Treg) counts and intracellular cytokine responses (TNF-α, IFN-γ, IL-10 and TGF-s) of mononuclear cell subsets were determined by flow cytometry after in vitro stimulation with PMA/ionomycin. Results Sorafenib did not alter the elevated TGF-s and IL-10 mRNA levels or elevated frequencies of IL-10 and TGF-s producing monocytes and had no influence on type 1 cytokine responses in pB. CD4+CD25high FOXP3+/CD3+ T cells, likely representing Treg cells, decreased during sorafenib therapy. Conclusions In vivo, sorafenib treatment was associated with a decrease in frequency of Treg cells without influencing the function of peripheral immune effector cells. Therefore, although sorafenib did not convert the immunosuppressive phenotype associated with mRCC, it seemed to be a possible candidate for combination with immunotherapy.

This study investigated the immunogenicity of Wilms tumor gene product 1 (WT1)–peptide vaccination in WT1-expressing acute myeloid leukemia (AML) and myelodysplastic syndrome (MDS) patients without curative treatment option. Vaccination consisted of granulocyte-macrophage colony-stimulating factor subcutaneously days 1 to 4, and WT1.126-134 peptide and 1 mg keyhole limpet hemocyanin on day 3. The initial 9 patients received 4 vaccinations biweekly, then monthly, and the subsequent 10 patients received continual biweekly vaccination. Seventeen AML patients and 2 refractory anemia with excess blasts patients received a median of 11 vaccinations. Treatment was well tolerated. Objective responses in AML patients were 10 stable diseases (SDs) including 4 SDs with more than 50% blast reduction and 2 with hematologic improvement. An additional 4 patients had clinical benefit after initial progression, including 1 complete remission and 3 SDs. WT1 mRNA levels decreased at least 3-fold from baseline in 35% of patients. In 8 of 18 patients, WT1-tetramer+ T cells increased in blood and in 8 of 17 patients in bone marrow, with a median frequency in bone marrow of 0.18% at baseline and 0.41% in week 18. This WT1 vaccination study provides immunologic, molecular, and preliminary evidence of potential clinical efficacy in AML patients, warranting further investigations.

Regulatory T-cells (Treg) have been the focus of immunologic research due to their role in establishing tolerance for harmless antigens versus allowing immune responses against foes. Increased Treg frequencies measured by mRNA expression or protein synthesis of the Treg marker FOXP3 were found in various cancers, indicating that dysregulation of Treg levels contributes to tumor establishment. Furthermore, they constitute a key target of immunomodulatory therapies in cancer as well as transplantation settings. One core obstacle for understanding the role of Treg, thus far, is the inability of FOXP3 mRNA or protein detection methods to differentiate between Treg and activated T cells. These difficulties are aggravated by the technical demands of sample logistics and processing. Based on Treg-specific DNA demethylation within the FOXP3 locus, we present a novel method for monitoring Treg in human peripheral blood and solid tissues. We found that Treg numbers are significantly increased in the peripheral blood of patients with interleukin 2–treated melanoma and in formalin-fixed tissue from patients with lung and colon carcinomas. Conversely, we show that immunosuppressive therapy including therapeutic antibodies leads to a significant reduction of Treg from the peripheral blood of transplantation patients. In addition, Treg numbers are predictively elevated in the peripheral blood of patients with various solid tumors. Although our data generally correspond to data obtained with gene expression and protein-based methods, the results are less fluctuating and more specific to Treg. The assay presented here measures Treg robustly in blood and solid tissues regardless of conservation levels, promising fast screening of Treg in various clinical settings. [Cancer Res 2009;69(2):599–608]

Here we report that genetically engineered yeast of the strain Saccharomyces cerevisiae expressing full-length influenza matrix protein (IMP) attached to the yeast cell wall are a very versatile host for antigen delivery. Feeding of dendritic cells with either intact yeast expressing IMP protein or soluble IMP protein cleaved off the cell wall resulted in protein uptake, processing and cross-presentation of IMP-derived peptides. This process was analysed using previously established T-cell lines recognizing the immuno-dominant 58–66 peptide when presented by HLA-A2*0201 complexes. In addition, IMP 58–66 /HLA-A2*0201-specific antibodies were selected from a naive phage library which confirmed that peptide presentation was an active process of endocellular uptake and not just a result of external peptide loading. Moreover, MHC peptide antibodies could block the recognition of peptide-presenting dendritic cells by IMP 58–66 -specific T-cells in a dose dependent manner. There was no difference in T-cell recognition when either intact yeast or yeast cell extracts were used for DC feeding. Together, these data demonstrate that yeast derived proteins either in their soluble form or as part of a whole yeast vaccine are taken up, processed and presented by dendritic cells in HLA class I context.

Purpose: Preclinical investigations suggest that histamine dihydrochloride (HDC) protects T cells and natural killer cells from inhibition by monocyte-derived reactive oxygen metabolites and synergizes with interleukin (IL) 2 in inducing T-cell activation. Here, we investigate whether this mechanism is operational in patients with melanoma treated with HDC as an adjunct to IL-2. Experimental Design: Melanoma patients having liver metastases were treated with IL-2 with or without HDC within a randomized, multicenter, phase III trial. The effect of HDC on type 1 and type 2 T-cell cytokine production was investigated in peripheral blood samples from 19 patients with the use of intracellular cytokine flow cytometry. Melanoma-specific T-cell responses were analyzed in eight HLA-A2–positive patients. Results: Frequencies of CD3+ T cells producing IFN-γ (type 1 T cells) in response to phorbol myristate acetate/ionomycin increased (median, 1.8-fold) in patients receiving IL-2 plus HDC but not in those receiving IL-2 alone (P < 0.01 for comparison between arms). In contrast, the number of IL-13-producing type 2 T cells that increased in patients after treatment with IL-2 was not modulated by HDC. Melanoma- and tyrosinase-specific IFN-γ and IL-13-producing T cells were detected in two of four HLA-A2–positive patients with melanoma following treatment with HDC + IL-2. Conclusions: Treatment of patients with stage IV melanoma with HDC in combination with IL-2 increases type 1 T-cell responses and may promote induction of melanoma-specific T cells. These effects are of relevance for tumor immunotherapy and provide a potential mechanism for the clinical efficacy of HDC added to IL-2.

PAX2 is a transcription factor and member of the highly conserved family of paired box genes. PAX2 is aberrantly expressed in a variety of solid and hematologic malignancies. PAX2 regulates the transcription factor Wilms tumor gene 1, which is a promising target of cancer immunotherapy. The aim of this study was to apply a modified reverse immunology strategy to identify immunogenic epitopes of PAX2 which could be useful for cancer immunotherapy. Thirteen potential HLA-A*0201 epitopes were predicted by a major histocompatibility complex binding algorithm (SYFPEITHI) and a proteasome cleavage algorithm (PAProC) and screened for recognition by T cells from HLA-A*02-positive cancer patients using intracellular cytokine cytometry. Epitope-specific T cells were generated from CD4CD25 regulatory T-cell-depleted peripheral blood mononuclear cell. Nine of 20 colorectal cancer patients, 1 of 13 renal cell carcinoma patients, and 2 of 17 lymphoma patients had a spontaneous CD8 T-cell response toward at least 1 of 6 PAX2 peptide pools. None of the 20 healthy subjects showed reactivity toward PAX2. PAX2.337-345 (TLPGYPPHV)-specific T cells could repeatedly be generated, which specifically lysed the PAX2 expressing colorectal tumor cell line SW480. In this study, a modified reverse immunology strategy was employed to identify a first immunogenic HLA-A*0201 restricted T-cell epitope and natural ligand of the tumor antigen PAX2. Thus, PAX2 is another embryonic transcription factor, which is of potential interest as immunotherapy target antigen.

Although new treatment options for patients with advanced renal cell cancer (RCC) have been developed within recent years, vaccination is still a promising emerging treatment option. An increasing number of tumor-associated antigens (TAA) available for RCC are currently used and analyzed for their efficacy for antigen-specific vaccine strategies. Recently, antigen-specific vaccination with dendritic cells in patients with metastatic RCC was shown to induce cytotoxic T cell response associated with objective clinical responses in some of the patients. Furthermore, current studies focus on the development of more effective vaccine regimes, such as the application of polyvalent, HLA-independent RNA coding for multiple TAA and adjuvants. First results demonstrate promising clinical and immunological efficacy. The efficacy of antigen-specific vaccination might be improved by a combination of tyrosine kinase inhibitors, since sunitinib was shown to promote T cell induction following vaccination in a mouse model and elimination of regulatory T cells.

Background: Sorafenib and sunitinib are tyrosine kinase inhibitors with largely overlapping specificities, approved for the treatment of metastatic renal-cell carcinoma (RCC). It was unclear whether the similarities of the two drugs would lead to complete cross-resistance, or whether sequential application would be efficacious. Methods: Patients with metastatic RCC and progression on sorafenib treatment were treated with repeated cycles of sunitinib, 50 mg for 4 weeks, followed by a 2-week break. Response (Response Evaluation Criteria in Solid Tumors, RECIST) was assessed every second cycle. Results: A total of 22 patients with progression on sorafenib were accrued. Initially, sorafenib treatment was efficacious in all patients, with 7 showing partial response (PR) and 15 stable disease (SD), and subsequent disease progression. With 4 PRs (18%) and 12 SD (55%) a disease control rate of 73% was achieved. The median progression-free survival (PFS) on sunitinib was 21.5 weeks; median overall survival (OS) was not reached. Estimated 1-year PFS and OS were 31 and 60%, respectively. There was no apparent relationship between response to sorafenib and outcome on sunitinib. Conclusion: In our cohort of patients with RCC and progression after initial efficacy of sorafenib, the efficacy data of second-line sunitinib were close to published results of first-line treatment, suggesting limited clinically relevant cross-resistance.

Purpose: The transcription factor Wilms tumor protein 1 (WT1) belongs to a new generation of tumor antigens, as it is essential for tumor cell proliferation and is highly expressed in various hematologic and solid malignancies. The aim of this study was to apply a modified reverse immunology strategy to identify immunogenic epitopes of WT1 which could be useful for immunotherapy.Experimental Design: Potential HLA-A*01 epitopes predicted by a MHC binding algorithm were screened for recognition by peripheral blood mononuclear cells (PBMC) from patients with spontaneous T cell responses using intracellular cytokine cytometry. Epitope processing was shown by proteasomal cleavage. Epitope-specific T cells were generated from CD4+CD25+ regulatory T cell–depleted PBMC.Results: One of five predicted HLA-A*01-binding candidate epitopes showed high immunogenicity as 5 of 14 patients with hematologic malignancies had WT1.317-327–reactive T cells ranging from 0.4% to 1.5% of CD3+CD8+ T cells. Proteasomal degradation assays indicated the cleavage of WT1.317-327. The depletion of regulatory T cells from PBMCs enabled the rapid expansion of WT1.317-327–specific CTL, whereas no CTL could be generated from unfractionated PBMC. WT1.317-327–specific CTL efficiently lysed an autologous WT1-expressing tumor cell line but not HLA-A*01–negative WT1-expressing tumor cells. Immunogenicity of the epitope across histologies was verified by the demonstration of spontaneous ex vivo WT1.317-327–specific T cell responses in two of six patients with HLA-A*01–positive melanoma or lung cancer.Conclusion: In this study, a modified reverse immunology strategy was employed to identify a first immunogenic HLA-A*01–restricted T cell epitope of the tumor antigen WT1, which is of considerable interest for use in vaccination trials.

T-cell trafficking is determined by expression patterns of chemokine receptors. The chemokine receptor CXCR3 is expressed on a subpopulation of type 1 T cells and plays an important role for migration of T cells into inflamed and tumor tissues. Here, we studied the chemokine receptor expression on specific T cells generated against the neoantigen keyhole limpet hemocyanin (KLH) in patients who had been immunized in the context of a tumor peptide vaccination trial with or without the adjuvant granulocyte-macrophage colony-stimulating factor (GM-CSF). In patients immunized in the presence of GM-CSF the fraction of CXCR3(+) KLH-specific T cells was significantly higher than in patients immunized in the absence of GM-CSF (median 45 vs. 20%, P = 0.001). In contrast, the chemokine receptor CCR4, associated with migration to the skin was found in both cohorts on less than 10% of KLH-specific T cells. These results show that CXCR3 expression on vaccine-induced T cells can be modulated by modifying the local vaccine milieu.

The goal of vaccination against tumors is the induction of effector T cells mediating tumor destruction and memory T cells providing long-term immunity. Several previous studies in patients vaccinated with major histocompatibility complex (MHC) class I peptides failed to show induction of central memory T cells, which are considered important to provide long-term memory. This study examined the subset composition and function of specific T cells generated by immunization with MHC class I binding tyrosinase peptides in combination with the adjuvants granulocyte-macrophage colony-stimulating factor and keyhole limpet hemocyanin in peripheral blood (PB) and bone marrow (BM) of melanoma patients. Most of the tyrosinase-specific T cells in PB had a CD45RA(+)CCR7(-) effector phenotype. In contrast to this, a large subset of tyrosinase-specific T cells in BM were memory T cells, including CD45RA(+)CCR7(-) central and CD45RA(-)CCR7(-) effector memory T cells. BM tyrosinase-specific T cells were functional, because they produced interferon-gamma and had a high proliferative potential. This study suggests that peptide vaccination can generate a fully functional memory T-cell response characterized by central and effector memory phenotypes, proliferative potential, and BM tropism.

There is considerable interest in immunotherapeutic approaches for lymphoma. The expression of proteinase inhibitor 9 (PI-9), a molecule that inactivates granzyme B, is considered an immune escape mechanism in lymphoma. Further, lymphomas frequently overexpress the antiapoptotic molecule bcl-2, which is able to inhibit perforin-dependent cytotoxic pathways. In this study, the impact of PI-9 and bcl-2 expression on the sensitivity of lymphomas to T- and natural killer (NK) cell–mediated cytotoxicity was analyzed. We found PI-9 expression in 10 of 18 lymphoma cell lines and in 9 of 14 primary lymphomas. Overexpression of bcl-2 was found in 8 of 18 cell lines and in 12 of 14 primary lymphomas. All lymphoma cells were sensitive to cytolysis by specific T cells and cytokine-activated NK cells, and no difference in sensitivity was observed with respect to PI-9 or bcl-2 expression. Cytolysis was mediated predominantly through perforin-dependent pathways despite expression of PI-9 and bcl-2. Interestingly, the majority of lymphoma cells were resistant to cytolysis by resting allogeneic NK cells. This was due to the failure of lymphomas to induce degranulation of resting NK cells. These results show that resistance to perforin-dependent pathways is not a relevant immune escape mechanism in lymphoma and therefore is unlikely to impair clinical outcome of immunotherapeutic approaches.

This pilot study was carried out to gain a first insight into the effects of peptide vaccination in melanoma patients in the high-risk adjuvant disease setting. From the adjuvant peptide vaccination studies carried out in our institution since 1998, we identified all melanoma patients with a history of at least 3 completely resected metastases during the year preceding enrollment into the trial and describe the clinical and immunologic observations. Out of a total of 44 patients with resected cutaneous melanoma entered into adjuvant peptide vaccination trials, 9 patients were identified with more than 3 metastases in the year before vaccination. After initiation of vaccination, 2 patients remained relapse-free for 27 and 42+ months, 2 patients experienced single or several initial relapses and subsequent relapse-free intervals of 18 and 65+ months, whereas 5 patients progressed. In both patients with relapse after prolonged relapse-free intervals, the relapses were initially confined to the small intestine and could be resected. Induction or boosting of functional tyrosinase peptide-specific T cells was noted in 6 of 8 patients, including all 4 patients with prolonged relapse-free intervals. In conclusion, adjuvant peptide vaccination was associated with cessation of recurrences in 4 of 9 patients, of whom all 4 had an immunologic response to the vaccine.

T cells play a central role in the defense against cancer. Assays to quantitate antigen-specific T cells have recently gained much interest especially in the field of tumor vaccination. The novel generation of sensitive T cell assays facilitates the direct ex vivo quantitation of specific T cell responses. Furthermore, various T cell functions can be detected by flow cytometry including the production of cytokines, proliferation, cytotoxic functions and migratory responses. The high sensitivity of modern flow cytometry allows characterizing antigen-specific T cells after stimulation with specific peptides or by combining functional flow cytometry with tetramer staining. This chapter focuses on the technique of intracellular cytokine staining for analysis of tumor-specific T cell responses.

In general, metastases to the small intestine are rare, and mostly occur in melanoma. CCR9 has been shown to be the principal chemokine receptor for the thymus expressed chemokine (TECK), a chemokine selectively expressed in the small intestine and thymus. Here we show that CCR9 is highly expressed on melanoma cells and all melanoma cell lines isolated from small intestinal metastases, and on a proportion of cell lines from other sites. Only melanoma cells and cell lines from small intestinal metastases, however, were responsive to the CCR9 ligand TECK, as assessed by receptor downregulation and by actin polymerization. CCR9 expression was also found on the adenocarcinoma cell line CaCo-2 expressing characteristics of enterocytic differentiation, but not on any other cell line isolated from colorectal, breast, and lung cancer. Our data provide evidence that the aberrant functional cell surface expression of an organ-specific chemokine receptor is associated with metastasis to this site. The regulation of receptor function seems to be a critical step in the metastatic process.

In previous studies CD8+ T cells specific for melanocyte antigens have been frequently found in melanoma patients responding to interleukin-2 (IL-2)-based therapies. In our study we analyzed the suitability of using circulating T cells from melanoma patients with clinical response after IL-2-based therapy to identify novel T-cell epitopes from defined tumor antigens. Using unstimulated peripheral blood mononuclear cells and the interferon-gamma (IFN-gamma) ELISPOT assay, we studied CD8(+) T-cell responses against 5 peptides from the tumor antigen tyrosinase (Tyr) selected by epitope prediction using an HLA-A1-binding computer algorithm. T cells specifically secreting IFN-gamma in response to 3 of these 5 peptides, namely, Tyr (454-463), Tyr (146-156) and Tyr (243-251), could be detected in 4 of 4 HLA-A1-positive patients with clinical response. In contrast, no T-cell responses against these peptides were seen in 6 HLA-A1-positive melanoma patients with progressive disease and in 8 healthy subjects. We could generate specific cytotoxic T lymphocytes (CTL) against Tyr (454-463) using peptide-pulsed autologous dendritic cells as antigen-presenting cells. The induced CTLs efficiently killed melanoma cells that express HLA-A1 and tyrosinase. The peptides Tyr (146-156) and Tyr (243-251) had recently been identified as CTL epitopes by other groups. Further ex vivo characterization of the T cells reactive against the novel epitope Tyr (454-463) in 1 patient by multicolor flow cytometry showed specific CD3+/CD8+/IFN-gamma+ T cells with frequencies of up to 0.41% of the CD3+/CD8+ T-cell population. Most of this T-cell population also expressed granzyme B. Our data confirm that in patients with tumor regressions induced by immunotherapy or chemoimmunotherapy circulating T cells reactive with tyrosinase epitopes can frequently be detected. Peripheral blood T cells from such patients are a valuable source for screening peptides selected by epitope prediction This strategy facilitates the rapid identification of immunogenic T-cell epitopes that are probable targets of immune-mediated tumor rejection.

To defend the host from malignancies, the immune system can spontaneously raise CD8(+) T-cell responses against tumor antigens. Investigating the functional state of tumor-reactive cytolytic T cells in cancer patients is a key step for understanding the role of these cells in tumor immunosurveillance and for evaluating the potential of immunotherapeutic approaches of vaccination against cancer. In this study we identified a subset of circulating tumor-reactive CD8(+) T lymphocytes, which specifically secreted IFN-gamma after exposition to autologous tumor cell lines in stage IV metastatic melanoma patients. Additional phenotypic characterization using multicolor flow cytometry revealed that a significant fraction of these cells were CD45RA(+)CCR7(-), a phenotype that has been proposed recently to characterize cytolytic effectors potentially able to home into inflamed tissues. In the case of an HLA-A2-expressing patient, the antigen specificity of this population was identified by using HLA-A2/peptide multimers incorporating a tyrosinase-derived peptide. Consistently with their phenotypic characteristics, A2/tyrosinase peptide multimer(+) CD8(+) T cells, isolated by cell sorting, were directly lytic ex vivo and able to specifically recognize tyrosinase-expressing tumor cells. Overall, these results provide the first evidence that a proportion of melanoma patients have circulating tumor-reactive T cells, which are lytic effectors cells.

The detection of antigen-induced IFNgamma secretion at the single cell level can be used to identify and enumerate antigen-reactive T cells from peripheral blood. This study was performed to analyze the suitability of T cell enumeration by flow cytometry in comparison with the ELISPOT assay. Peripheral blood mononuclear cell (PBMC) samples from six HLA-A2+ healthy subjects were analysed for the frequency of influenza-reactive CD8+ T cells by flow cytometry detecting either intracellular IFNgamma (IC-FC) or secreted IFNgamma (S-FC). All samples were also analysed by IFNgamma ELISPOT assay. The frequency of influenza peptide-reactive T cells determined by IC-FC was 0.01 to 0.34% of CD8+ T cells and by ELISPOT assay 0.02 to 0.23% of CD8+ T cells (n=6 subjects) with a high inter-assay reproducibility and a close correlation between the assays (r=0.77, P

The transcription factor Wilms tumor protein (WT) 1 belongs to a new generation of tumor antigens, which are essential for tumor cell proliferation. WT1 is highly expressed in AML and in MDS upon appearance of blasts. A phase II trial of vaccination with the HLA-A2-restricted WT1.126–134 peptide was performed in patients with AML and MDS and overexpression of WT1 to determine immunogenicity and clinical activity. Patients received vaccinations with 0.2 mg WT1.126–134 peptide (day 3), 62.5 mcg dendritic cell-stimulating adjuvant GM-CSF (days 1–4) and 1 mg T helper protein keyhole limpet hemocyanin (day 3). The initial 13 patients were to receive 4 biweekly and subsequent 4-weekly vaccinations, the subsequent 13 patients were continuously vaccinated biweekly. Vaccination was continued in absence of overt disease progression. WT1 levels were assessed by quantitative RT-PCR and WT1-specific T cell responses by tetramer analyses and cytokine flow cytometry. Response assessment following IWG-MDS criteria was used, capturing stable disease and hematologic improvement. A duration of 8 weeks was required for stable disease. Enrolment was completed in June 2006 with 24 patients with AML and 2 with MDS (RAEB). Of the 24 AML patients, 16 had > 5% marrow blasts at study onset (8 without prior chemotherapy, 4 with disease persistence following chemotherapy, 4 with PR), and 8 were in CR at high risk for relapse. A median of 10 (range 4 – 23) vaccinations was administered with 8 patients currently still under treatment. No significant toxicity occurred. To date, 22 patients are evaluable for clinical response. Overall, 8/16 patients with > 5% marrow blasts at study onset displayed clinical efficacy of vaccine treatment (SD or better). One AML patient achieved CR for 12 months after brief initial progression, and 7 patients had disease stabilization (2, 2+, 3, 3, 6, 10+, 14 months). One of these patients with RAEBII had a major response of neutrophils and platelets, and one AML patient had initial progression and subsequent transient complete clearance of peripheral blasts. WT1 transcripts as molecular disease marker decreased at least 3-fold (range 3-fold - >50-fold, median >10-fold) in 12 of 20 currently evaluated patients, including all 8 patients with evidence of clinical efficacy and 4 of 5 AML patients vaccinated in CR. The generation of a WT1-specific T cell response in peripheral blood and bone marrow was detected in 12 of 16 evaluated patients including all 6 of these 16 patients with evidence for clinical efficacy. This study shows that WT1 vaccination has promising antileukemia activity. A multicenter comparative WT1 vaccination study in CR patients at high risk of relapse is currently initiated.

Background: Recent data suggest that NK cell mediated antibody dependent cellular cytotoxicity (ADCC) is a major mechanism of action of the anti-CD20 monoclonal antibody (mAb) rituximab and the anti-CD52 mAb alemtuzumab, which are frequently applied in patients with non-Hodgkin’s lymphoma and chronic lymphocytic leukemia. However, the exact mechanisms leading to NK cell activation are not completely understood and the cytotoxic subpopulation of peripheral blood NK cells mediating ADCC remains to be defined. In order to quantify and characterize the NK cells mediating ADCC, we used a novel flow cytometric assay, which detects the lytic granule membrane protein CD107a as a marker for NK cell degranulation. Methods: PBMCs from healthy individuals were coincubated at 37°C for 3 h with different human leukemia and lymphoma cell lines. In each tube, containing 200μl effector/target suspension (4x105 cells), 15μl of PE-Cy5 conjugated anti-CD107a monoclonal antibody was added prior to incubation. To assess antibody dependent cellular cytotoxicity (ADCC) saturating concentrations (10μg/ml) of rituximab or alemtuzumab were used. After the first 1 h 5μl of the secretion inhibitor 2 mM monensin was added. At the end of coincubation cells were stained with mAbs (CD56, CD3, NKG2D, CD69, CD94, NKp30, NK46) for flow cytometry. NK cell-mediated cytotoxicity (specific lysis) was analyzed by flow cytometric detection of propidium iodide uptake. Results: After coincubation with NK sensitive K562 cells up to 6% of CD56+ cells expressed CD107a, indicating that a subpopulation of NK cells releases cytotoxic granules after contact with these target cells. In contrast, coincubation with NK-resistant leukemia cells (ML2, EHEB, DAUDI, RAJI, AM0-1, YT-1) was not followed by an increased surface expression of CD107a. However, when rituximab was added to CD20+ lymphoma or leukemia cells (EHEB, DAUDI, RAJI) we observed that up to 15% of NK cells expressed CD107a after coincubation. In contrast no increased CD107a surface expression was observed when rituximab was added to the CD20− cell lines AMO-0 and YT-1, which excludes unspecific NK cell activation. When alemtuzumab was added to the CD52+ cell lines AMO-1, DAUDI, EHEB, RAJI and YT-1, surface expression of CD107a on NK cells was increased considerably. The majority of degranulating NK cells had the phenotype: CD56dim, CD69+, NKG2D+, NKp30−, NKp46− and CD94−. Furthermore we found that the CD107a assay can also visualize ADCC under clinical conditions as we observed increased numbers of NK cells degranulating in response to CD20+ lymphoma cell lines in patients with non-Hodgkin’s lymphoma treated with rituximab. The number of degranulating NK cells was closely related to the concentration of rituximab and the effector:target ratio, showing a maximum at a ratio of 1:1 and concentrations above 5μg/ml. CD107a surface expression and specific lysis demonstrated a strong positive correlation (r2 = 0.99), confirming that NK cell cytotoxicity can be assessed by this method. Conclusion: The CD107a assay represents a promising new method not only for assessment of natural cytotoxicity on a single cell level but also for determination of ADCC in vitro and in patients treated with mAb. In clinical practice, it may help to find optimal doses and time schedules for the treatment with different mAbs.