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Leukemia : normal and malignant hemopoiesis 35(8), 2311-2324 (2021). doi:10.1038/s41375-021-01136-1, Published by Springer Nature, London

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Objectives Emerging treatments for relapsed or refractory multiple myeloma (rrMM) have led to increasing options for many patients. This study aimed to assess changes in utilization of these options in Germany with a focus on modern triplet regimens including new agents, such as carfilzomib, ixazomib, elotuzumab and daratumumab, and to evaluate whether this had an impact on rrMM‐related outcomes over time. Methods The study population consisted of 1255 rrMM patients who were assigned to one of the following 6 treatment groups: immunomodulatory drug (IMiD)‐based doublets, proteasome inhibitor (PI)‐based doublets, daratumumab monotherapy, PI‐IMiD‐based triplets, monoclonal antibodies (mAbs)‐based triplets, or other treatment. Results Use of triplet‐based therapy regimens increased from 5.9% in 2014 to 31.4% in 2017. In parallel, use of IMiD‐based doublets decreased from 74.3% in 2014 to 37.6% in 2017. Over the same time period, the risk of death decreased by 32% and the risk of hospitalization which was reduced by 30%. The risk for serious adverse events remained unchanged. Conclusions Between 2014 and 2017, the use of triplet‐based therapy regimens for rrMM in Germany has significantly increased and this was associated with a significant decline in deaths and hospitalizations without an increased incidence of serious adverse events.

Drug combinations that target critical pathways are a mainstay of cancer care. To improve current approaches to combination treatment of chronic lymphocytic leukemia (CLL) and gain insights into the underlying biology, we studied the effect of 352 drug combination pairs in multiple concentrations by analysing ex vivo drug response of 52 primary CLL samples, which were characterized by “omics” profiling. Known synergistic interactions were confirmed for B-cell receptor (BCR) inhibitors with Bcl-2 inhibitors and with chemotherapeutic drugs, suggesting that this approach can identify clinically useful combinations. Moreover, we uncovered synergistic interactions between BCR inhibitors and afatinib, which we attribute to BCR activation by afatinib through BLK upstream of BTK and PI3K. Combinations of multiple inhibitors of BCR components (e.g., BTK, PI3K, SYK) had effects similar to the single agents. While PI3K and BTK inhibitors produced overall similar effects in combinations with other drugs, we uncovered a larger response heterogeneity of combinations including PI3K inhibitors, predominantly in CLL with mutated IGHV, which we attribute to the target’s position within the BCR-signaling pathway. Taken together, our study shows that drug combination effects can be effectively queried in primary cancer cells, which could aid discovery, triage and clinical development of drug combinations.

Preliminary data suggest that allogeneic stem cell transplantation (allo-SCT) may be effective in T-prolymphocytic leukemia (T-PLL). The purpose of the present observational study was to assess the outcome of allo-SCT in patients aged 65 years or younger with a centrally confirmed diagnosis of T-PLL. Patients were consecutively registered with the EBMT at the time of transplantation and followed by routine EBMT monitoring but with an extended dataset. Between 2007 and 2012, 37 evaluable patients (median age 56 years) were accrued. Pre-treatment contained alemtuzumab in 95% of patients. Sixty-two percent were in complete remission (CR) at the time of allo-SCT. Conditioning contained total body irradiation with 6 Gy or more (TBI6) in 30% of patients. With a median follow-up of 50 months, the 4-year non-relapse mortality, relapse incidence, progression-free (PFS) and overall survival were 32, 38, 30 and 42%, respectively. By univariate analysis, TBI6 in the conditioning was the only significant predictor for a low relapse risk, and an interval between diagnosis and allo-SCT of more than 12 months was associated with a lower NRM. This study confirms for the first time prospectively that allo-SCT can provide long-term disease control in a sizable albeit limited proportion of patients with T-PLL.

The anti-tumor efficacy of TCR-engineered T cells in vivo depends largely on less-differentiated subsets such as T cells with naive-like T cell (TN) phenotypes with greater expansion and long-term persistence. To increase these subsets, we compared the generation of New York esophageal squamous cell carcinoma-1 (NY-ESO-1)-specific T cells under supplementation with either IL-2 or IL-7/IL-15. PBMCs were transduced with MS3II-NY-ESO-1-siTCR retroviral vector. T cell generation was adapted from a CD19-specific CART cell production protocol. Comparable results in viability, expansion and transduction efficiency of T cells under stimulation with either IL-2 or IL-7/IL-15 were observed. IL-7/IL-15 led to an increase of CD4+ T cells and a decrease of CD8+ T cells, enriched the amount of TN among CD4+ T cells but not among CD8+ T cells. In a 51Cr release assay, similar specific lysis of NY-ESO-1-positive SW982 sarcoma cells was achieved. However, intracellular cytokine staining revealed a significantly increased production of IFN-γ and TNF-α in T cells generated by IL-2 stimulation. To validate these unexpected findings, NY-ESO-1-specific T cell production was evaluated in another protocol originally established for TCR-engineered T cells. IL-7/IL-15 increased the proportion of TN. However, the absolute number of TN did not increase due to a significantly slower expansion of T cells with IL-7/IL-15. In conclusion, IL-7/IL-15 does not seem to be superior to IL-2 for the generation of NY-ESO-1-specific T cells. This is in sharp contrast to the observations in CD19-specific CART cells. Changes of cytokine cocktails should be carefully evaluated for individual vector systems.

Background Chimeric antigen receptor engineered T (CAR-T) cell therapy is a promising approach currently revolutionizing the field of cancer immunotherapy. However, data concerning clinical-grade CAR-T cell stability and functionality after months of cryopreservation have not been released by companies so far. To investigate the effect of cryopreservation on CAR-T cells and to further optimize the potency assays, we performed this study. Methods A third generation of CD19 CAR-T cells was manufactured according to Good Manufacturing Practice (GMP) requirements, which is applied to patients in an ongoing clinical phase 1 study. Quality control tests for sterility, endotoxin and mycoplasma were performed for each batch. Stability in terms of viability, recovery, transduction efficiency and functional capacity was determined using microscopy, multiparametric flow cytometry as well as chromium-51 release tests. Results Up to 90days of cryopreservation had no influence on viability, recovery and transduction efficiency of CAR-T cells. However, higher cell concentration for cryopreservation could alter the cell viability and recovery but not the transduction efficiency. Moreover, directly after thawing, both the quantity and quality of the functionality of CAR-T cells were transiently hampered by the negative effects of cryopreservation. Notably, the impaired functionality could be fully restored and even strengthened after an overnight resting process. Discussion Cryopreservation is a challenge for the functional activity of CAR-T cells. However, CAR-T cells regain their potency by overnight incubation at 37°C, which mimics the clinical application setting. Therefore, an overnight resting step should be included in in vitro potency assays.

Despite encouraging results with chimeric antigen receptor T (CART) cells, outcome can still be improved by optimization of the CART cell generation process. The proportion of less-differentiated T cells within the transfused product is linked to enhanced in vivo CART cell expansion and long-term persistence. The clinically approved PI3Kδ inhibitor idelalisib is well established in the treatment of B cell malignancies. Besides B cell receptor pathway inhibition, idelalisib can modulate T cell differentiation and function. Here, detailed longitudinal analysis of idelalisib-induced effects on T cell phenotype and function was performed during CART cell production. A third generation CD19.CAR.CD28.CD137zeta CAR vector system was used. CART cells were generated from peripheral blood mononuclear cells of healthy donors (HDs) and chronic lymphocytic leukemia (CLL) patients. Idelalisib-based CART cell generation resulted in an enrichment of less-differentiated naïve-like T cells (CD45RA+CCR7+), decreased expression of the exhaustion markers PD-1 and Tim-3, as well as upregulation of the lymph node homing marker CD62L. Idelalisib increased transduction efficiency, but did not impair viability and cell expansion. Strikingly, CD4:CD8 ratios that were altered in CART cells from CLL patients were approximated to ratios in HDs by idelalisib. Furthermore, in vivo efficacy of idelalisib-treated CART cells was validated in a xenograft mouse model. Intracellular TNF-α and IFN-γ production decreased in presence of idelalisib. This effect was reversible after resting CART cells without idelalisib. In summary, PI3Kδ inhibition with idelalisib can improve CART cell products, particularly when derived from CLL patients. Further studies with idelalisib-based CART cell generation protocols are warranted.

The folding and export of proteins and hydrolysis of unfolded proteins are disbalanced in the endoplasmic reticulum (ER) of cancer cells, leading to so‐called ER stress. Agents further augmenting this effect are used as anticancer drugs including clinically approved proteasome inhibitors bortezomib and carfilzomib. However, these drugs can affect normal cells, which also rely strongly on ER functions, leading, for example, to accumulation of reactive oxygen species (ROS). To address this problem, we have developed ER‐targeted prodrugs activated only in cancer cells in the presence of elevated ROS amounts. These compounds are conjugates of cholic acid with N‐alkylaminoferrocene‐based prodrugs. We confirmed their accumulation in the ER of cancer cells, their anticancer efficacy, and cancer cell specificity. These prodrugs induce ER stress, attenuate mitochondrial membrane potential, and generate mitochondrial ROS leading to cell death via necrosis. We also demonstrated that the new prodrugs are activated in vivo in Nemeth‐Kellner lymphoma (NK/Ly) murine model., A fluorogenic N‐alkylaminoferrocene‐based prodrug activated by reactive oxygen species in vitro and in vivo was developed that is cancer cell specific and targets the endoplasmic reticulum.

Despite the extensive catalogue of recurrent mutations in chronic lymphocytic leukaemia (CLL), the diverse molecular driving events and the resulting range of disease phenotypes remain incompletely understood. To study the molecular heterogeneity of CLL, we performed RNA-sequencing on 184 CLL patient samples. Unsupervised analysis revealed two major independent axes of gene expression variation: the first one aligned with the mutational status of the immunoglobulin heavy variable (IGHV) genes, and concomitantly, with the three-group stratification of CLL by global DNA methylation pattern, and affected biological functions including B- and T-cell receptor signaling. The second one aligned with trisomy 12 status and affected chemokine signaling. Furthermore, we searched for differentially expressed genes associated with gene mutations and copy-number aberrations and detected strong signatures for TP53, BRAF and SF3B1, as well as for del(11)(q22.3), del(17)(p13) and del(13)(q14) beyond the dosage effect. We discovered strong non-additive effects (i.e., genetic interactions, or epistasis) of IGHV mutation status and trisomy 12 on multiple phenotypes, including the expression of 893 genes. Multiple types of epistasis were observed, including synergy, buffering, suppression and inversion. Our study reveals previously underappreciated gene expression signatures for (epi)genomic variants in CLL and the presence of epistasis between them. The findings will serve as a reference for a functional resolution of CLL molecular heterogeneity.

Chimeric antigen receptor (CAR) T cells directed against CD19 (CD19.CAR T cells) have yielded impressive clinical responses in the treatment of patients with lymphoid malignancies. However, resistance and/or relapse can limit treatment outcome. Risk of tumor escape can be reduced by combining treatment strategies. Selective inhibitors of nuclear export (SINEs) directed against nuclear exportin‑1 (XPO1) have demonstrated anti‑tumor efficacy in several hematological malignancies. The aim of the present study was to evaluate the combination of CAR T cells with the SINE compounds eltanexor and selinexor. As expected, eltanexor and selinexor were toxic to CD19‑positive malignant cells and the sensitivity of cells towards SINEs correlated with the levels of XPO1‑expression in ALL cell lines. When SINEs and CAR T cells were simultaneously combined, SINEs exerted toxicity towards CAR T cells and impaired their function affecting cytotoxicity and cytokine release ability. Flow cytometry and western blot analysis revealed that eltanexor decreased the cytoplasmic concentration of the transcription factor phosphorylated‑STAT3 in CAR T cells. Due to CAR T‑cell toxicity, sequential use of SINEs and CAR T cells was evaluated: Cytotoxicity of CAR T cells increased significantly when target cells were pre‑treated with the SINE compound eltanexor. In addition, exhaustion of CAR T cells decreased when target cells were pre‑treated with eltanexor. In summary, whereas the concomitant use of SINEs and CAR T cells does not seem advisable, sequential use of SINEs and CAR T cells might improve the anti‑tumor efficacy of CAR T cells.

The transcription factor Eomesodermin (EOMES) promotes IL-10 production of CD4+T-cells, which has been linked to immunosuppressive and cytotoxic activities. We detected EOMES-expressing CD4+T-cells in lymph node samples of patients with chronic lymphocytic leukemia (CLL) or diffuse large B-cell lymphoma. This was in line with an observed expansion of EOMES-positive CD4+T-cells in leukemic Eµ-TCL1 mice, a well-established model of CLL, and upon adoptive transfer of TCL1 leukemia in mice. Transcriptome and flow cytometry analyses revealed that EOMES does not only drive the transcription of IL-10, but rather controls a unique differentiation program in CD4+T-cells. Moreover, EOMES was necessary for the accumulation of a specific CD4+T-cell subset that expresses IFNγ and IL-10, as well as inhibitory receptors, like PD-1 and LAG3. T-cell transfer studies in leukopenicRag2-/-mice showed that EOMES-deficient CD4+T-cells were inferior in controlling TCL1 leukemia development compared to wildtype T-cells, even though expansion ofEomes-/-CD4+T-cells was observed. We further showed that control of TCL1 leukemia was driven by IL-10 receptor-mediated signals, asIl10rb-deficient CD4+T-cells showed impaired anti-leukemia activity. Altogether, our data suggest that IL-10 producing PD-1+CD4+T-cells contribute to CLL control in an EOMES- and IL-10R-dependent manner.

Chimeric antigen receptor T (CART) cells targeting CD19 have shown promising results in the treatment of chronic lymphocytic leukemia (CLL). However, efficacy seems to be inferior compared to diffuse large B-cell lymphoma or acute lymphoblastic leukemia. Impaired T-cell fitness of CLL patients may be involved in treatment failure. Less-differentiated naive-like T cells play an important role in CART expansion and long-term persistence in vivo. These cells are sparse in CLL patients. Therefore, optimization of CART cell production protocols enriching less differentiated T cell subsets may overcome treatment resistance. The B-cell receptor inhibitor ibrutinib targeting Bruton's tyrosine kinase (BTK) is approved for the treatment of CLL. Besides BTK, ibrutinib additionally inhibits interleukin-2-inducible T-cell kinase (ITK) which is involved in T-cell differentiation. To evaluate the effect of ibrutinib on CART cell production, peripheral blood mononuclear cells from nine healthy donors and eight CLL patients were used to generate CART cells. T-cell expansion and phenotype, expression of homing and exhaustion makers as well as functionality of CART cells were evaluated. CART cell generation in the presence of ibrutinib resulted in increased cell viability and expansion of CLL patient-derived CART cells. Furthermore, ibrutinib enriched CART cells with less-differentiated naive-like phenotype and decreased expression of exhaustion markers including PD-1, TIM-3 and LAG-3. In addition, ibrutinib increased the cytokine release capacity of CLL patient-derived CART cells. In summary, BTK/ITK inhibition with ibrutinib during CART cell culture can improve yield and function of CLL patient-derived CART cell products.

Enhanced in vivo expansion, long-term persistence of chimeric antigen receptor T (CART) cells, and efficient tumor eradication through these cells are linked to the proportion of less-differentiated cells in the CART cell product. Retronectin is well established as an adjuvant for improved retroviral transduction, while its property to enrich less-differentiated T cells is less known. In order to increase these subsets, this study investigated the effects of retronectin-mediated T-cell activation for CD19-specific CART cell production. Peripheral blood mononuclear cells of healthy donors and untreated chronic lymphocytic leukemia (CLL) patients without or with positive selection for CD3+ T cells were transduced with a CD19.CAR.CD28.CD137zeta third-generation retroviral vector. Activation of peripheral blood mononuclear cells was performed by CD3/CD28, CD3/CD28/retronectin, or CD3/retronectin. Interleukin-7 and -15 were supplemented to all cultures. Retronectin was used in all three activation protocols for retroviral transduction. Expansion was assessed by trypan blue staining. Viability, transduction efficiency, immune phenotype, and cytokine production were longitudinally analyzed by flow cytometry. Cytotoxic capacity of generated CART cells was evaluated using a classical chromium-51 release assay. Retronectin-mediated activation resulted in an enrichment of CD8+ cytotoxic CART cells and less-differentiated naïve-like T cells (CD45RA+CCR7+). Retronectin-activated CART cells showed increased cytotoxic activity. However, activation with retronectin decreased viability, expansion, transduction efficiency, and cytokine production, particularly of CLL patient-derived CART cells. Both retronectin-mediated activation protocols promoted a less-differentiated CART cell phenotype without comprising cytotoxic properties of healthy donor-derived CART cells. However, up-front retronectin resulted in reduced viability and expansion in CLL patients. This effect is probably attributed to the retronectin-mediated activation of B cells with prolonged CLL persistence. Consequently, CART cell expansion and generation failed. In summary, activation with retronectin should be performed with caution and may be limited to patients without a higher percentage of tumor cells in the peripheral blood.

Chimeric antigen receptor (CAR) T cell therapy can achieve outstanding response rates in heavily pretreated patients with hematological malignancies. However, relapses occur and they limit the efficacy of this promising treatment approach. The cellular composition and immunophenotype of the administered CART cells play a crucial role for therapeutic success. Less differentiated CART cells are associated with improved expansion, long-term in vivo persistence, and prolonged anti-tumor control. Furthermore, the ratio between CD4+ and CD8+ T cells has an effect on the anti-tumor activity of CART cells. The composition of the final cell product is not only influenced by the CART cell construct, but also by the culturing conditions during ex vivo T cell expansion. This includes different T cell activation strategies, cytokine supplementation, and specific pathway inhibition for the differentiation blockade. The optimal production process is not yet defined. In this review, we will discuss the use of different CART cell production strategies and the molecular background for the generation of improved CART cells in detail.

Burkitt lymphoma (BL) is a highly aggressive B-cell lymphoma associated with MYC translocation. Here, we describe drug response profiling of 42 blood cancer cell lines including 17 BL to 32 drugs targeting key cancer pathways and provide a systematic study of drug combinations in BL cell lines. Based on drug response, we identified cell line specific sensitivities, i.e. to venetoclax driven by BCL2 overexpression and partitioned subsets of BL driven by response to kinase inhibitors. In the combination screen, including BET, BTK and PI3K inhibitors, we identified synergistic combinations of PI3K and BTK inhibition with drugs targeting Akt, mTOR, BET and doxorubicin. A detailed comparison of PI3K and BTKi combinations identified subtle differences, in line with convergent pathway activity. Most synergistic combinations were identified for the BET inhibitor OTX015, which showed synergistic effects for 41% of combinations including inhibitors of PI3K/AKT/mTOR signalling. The strongest synergy was observed for the combination of the CDK 2/7/9 inhibitor SNS032 and OTX015. Our data provide a landscape of drug combination effects in BL and suggest that targeting CDK and BET could provide a novel vulnerability of BL.

Simple Summary Prodrugs that increase the level of reactive oxygen species (ROS) specifically in cancer cells while not affecting normal cells can potentially act as radiosensitizers for side effect free radiotherapy (RT). However, previously known ROS-amplifying prodrugs were found to not beuseful for this purpose. Since functional mitochondria are necessary for RT-resistance, we assumed that the problem could be solved by using dual prodrugs as radiosensitizers, both targeting mitochondria and simultaneously inducing ROS. In this paper, we explored this possibility. In particular, we developed an N-alkylaminoferrocene-based prodrug (2c) effective at low μMolar concentrations. Upon conversion to its active form 2c_BA in aqueous solution, it is efficiently taken up by cancer cells. This leads to the decrease of their mitochondrial membrane potential and the amplification of both, intracellular mitochondrial and total ROS generation. We found that 2c_BA acts as an efficient radiosensitizer in human head and neck squamous carcinoma cells in vitro. Abstract Radiotherapy (RT) efficacy can be improved by using radiosensitizers, i.e., drugs enhancing the effect of ionizing radiation (IR). One of the side effects of RT includes damage of normal tissue in close proximity to the treated tumor. This problem can be solved by applying cancer specific radiosensitizers. N-Alkylaminoferrocene-based (NAAF) prodrugs produce reactive oxygen species (ROS) in cancer cells, but not in normal cells. Therefore, they can potentially act as cancer specific radiosensitizers. However, early NAAF prodrugs did not exhibit this property. Since functional mitochondria are important for RT resistance, we assumed that NAAF prodrugs affecting mitochondria in parallel with increasing intracellular ROS can potentially exhibit synergy with RT. We applied sequential Cu+-catalyzed alkyne-azide cycloadditions (CuAAC) to obtain a series of NAAF derivatives with the goal of improving anticancer efficacies over already existing compounds. One of the obtained prodrugs (2c) exhibited high anticancer activity with IC50 values in the range of 5–7.1 µM in human ovarian carcinoma, Burkitt’s lymphoma, pancreatic carcinoma and T-cell leukemia cells retained moderate water solubility and showed cancer specificity. 2c strongly affects mitochondria of cancer cells, leading to the amplification of mitochondrial and total ROS production and thus causing cell death via necrosis and apoptosis. We observed that 2c acts as a radiosensitizer in human head and neck squamous carcinoma cells. This is the first demonstration of a synergy between the radiotherapy and NAAF-based ROS amplifiers.

Introduction Chimeric antigen receptor (CAR) T cell (CART) therapy has shown to be a new and very promising therapeutical method in patients with relapsed or refractory (r/r) acute lymphoblastic leukemia (ALL) and non-Hodgkin lymphoma (NHL). The investigator-initiated Heidelberg-CAR-T-cell-trial 1 (HD-CAR-1) evaluates both efficacy and safety of escalating doses of 3 rd-generation CD19-directed CARTs comprising CD28 and 4-1BB as costimulatory molecules in patients with r/r ALL and NHL. Leukapheresis, manufacturing, administration, patient monitoring and follow-up were all conducted in-house at the Heidelberg University Hospital. Methods Treatment was conducted with escalating doses of autologous 3 rd-generation CARTs after lymphodepletion with fludarabine (90 mg/m 2) and cyclophosphamide (1,500 mg/m 2) in patients with r/r acute lymphoblastic leukemia (ALL), chronic lymphocytic leukemia (CLL), or Non-Hodgkin's lymphoma (NHL), with subtype including diffuse large B-cell lymphoma (DLBCL), transformed follicular lymphoma (tFL) or mantle cell lymphoma (MCL). Treatment efficacy as well as occurrence of toxicities, such as cytokine release syndrome (CRS), immune effector cell-associated neurotoxicity syndrome (ICANS), infections or cytopenia, were evaluated. Following prior results regarding dose-dependent efficacy and excellent toxicity profile with dose levels (DL) I, II and III (10 6, 5×10 6 and 20×10 6 CARTs/m 2), a trial amendment was approved for treatment of patients with higher CART doses (DL IV, V and VI: 5x10 7, 10x10 7 and 20x10 7 CARTs/m 2). Results Overall, screening was performed for 32 patients. Two patients were considered screening failures due to rapidly progressive disease (PD) and uncontrolled hepatitis B infection, respectively; leading to 30 patients enrolled in the study. The HD-CAR-1 product was given to 27 patients (12 patients with ALL, four with CLL, four with MCL, five with DLBCL, and two with FL) in different dose levels (six patients with DL I, six patients with DL II, eight patients with DL III, 5 patients with DL IV, 2 patient with DL V). The CART product was not given to two patients due to PD and lethal septic complication, respectively. Severe CAR-T toxicity was rare, as only two patients developed CRS ≥ III°. Both patients received treatment with tocilizumab, while one was additionally treated with steroids. No ICANS ≥ III° were reported in the study. 54% of patients achieved a complete response (CR) with an overall response rate (ORR) of treated patients of 65%. In a subgroup response analysis, an ORR of 92% (83% CRs) with 50% of all patients achieving MRD-negative CR was seen in ALL patients. In the NHL/CLL cohort, an ORR of 43% and a CR rate of 29% were observed. Figure 1 displays OS and PFS results till the end of study (EOS, day +90). Conclusion Academic CART production was feasible for all enrolled patients. Patients responded clinically to treatment and CARTs displayed a highly favorable safety profile. Overall, HD-CAR-1 accounts for clinical evaluation of 3 rd generation CARTs. Figure 1 Figure 1. Disclosures Schubert: Gilead: Consultancy. Schmitt: TolerogenixX Ltd: Current Employment; Hexal: Other: Travel grant; Jazz Pharmaceuticals: Other: Travel grant; Therakos/Mallinckrodt: Research Funding. Müller-Tidow: Pfizer: Research Funding; Janssen: Consultancy, Research Funding; Bioline: Research Funding. Dreger: Riemser: Consultancy, Research Funding, Speakers Bureau; Janssen: Consultancy; BMS: Consultancy; Gilead Sciences: Consultancy, Speakers Bureau; AbbVie: Consultancy, Speakers Bureau; Novartis: Consultancy, Speakers Bureau; AstraZeneca: Consultancy, Speakers Bureau; Bluebird Bio: Consultancy; Roche: Consultancy, Speakers Bureau. Schmitt: MSD: Membership on an entity's Board of Directors or advisory committees; TolerogenixX: Current holder of individual stocks in a privately-held company; Kite Gilead: Other: Travel grants; Bluebird Bio: Other: Travel grants; Novartis: Other: Travel grants, Research Funding; Hexal: Other: Travel grants, Research Funding; Apogenix: Research Funding.

Despite major advances in the treatment of multiple myeloma (MM), it remains a largely incurable disease with long-term control often dependent on continuous therapy. More effective, better tolerated treatments are therefore required to achieve durable remissions and to improve the quality of life of MM patients. Adoptive immunotherapy employing T cells expressing chimeric antigen receptors (CAR) is currently among the most promising treatment approaches in cancer. Within the target portfolio for MM immunotherapy, B-cell maturation antigen (BCMA) is among the most widely studied target antigens. BCMA is consistently expressed on MM cells and, importantly, is not expressed in critical healthy tissue. For this reason, it is an ideal target for MM immunotherapy. Several clinical trials evaluating different BCMA-targeting CAR constructs have been initiated and early results are very promising. However, in this rapidly developing clinical landscape, the ultimate role of BCMA-specific CAR-T cell therapy remains unclear. In this review, we will summarize currently available clinical data on BCMA-directed CAR-T cells and discuss potential future perspective for this promising treatment approach in MM.

Background In Germany, several triplet therapies for treating relapsed or refractory multiple myeloma (rrMM) patients have recently been approved. While most of them are administered intravenously, ixazomib-based combination is the only orally bioavailable regimen. Objective To conduct a 1-year and 3-year budget impact analysis (BIA) of different novel triplets to treat patients with rrMM in second or subsequent therapy lines accounting for costs covered by German statutory health insurance (SHI). Methods A 3-state partitioned survival model (PSM) was developed to evaluate the budget impact of the following regimens: carfilzomib plus lenalidomide plus dexamethasone (KRd), elotuzumab plus lenalidomide plus dexamethasone (ERd), daratumumab plus lenalidomide plus dexamethasone (DRd), and ixazomib plus lenalidomide plus dexamethasone (IRd). The analysis included direct medical costs such as drug acquisition, comedication and preparation for parenteral solutions, drug administration and other 1-time costs, adverse event management costs and direct non-medical costs, such as transportation costs. Results Based on current drug market shares in German healthcare market, the estimated costs after 1 year of treatment was €551 million (KRd), €163 million (ERd), €584 million (DRd), and €95 million (IRd). The total budget impact of €1393 million is mainly driven by drug acquisition and subsequent therapy costs. Conclusion Among the regimens of interest, the oral-based therapy regimens offered cost advantages over intravenous-based therapy regimens. The higher overall costs of intravenous therapy regimens were attributed primarily to higher drug acquisition costs.

IntroductionChimeric antigen receptor (CAR) T cells spark hope for patients with CD19+ B cell neoplasia, including relapsed or refractory (r/r) acute lymphoblastic leukaemia (ALL) or r/r non-Hodgkin’s lymphoma (NHL). Published studies have mostly used second-generation CARs with 4-1BB or CD28 as costimulatory domains. Preclinical results of third-generation CARs incorporating both elements have shown superiority concerning longevity and proliferation. The University Hospital of Heidelberg is the first institution to run an investigator-initiated trial (IIT) CAR T cell trial (Heidelberg Chimeric Antigen Receptor T cell Trial number 1 [HD-CAR-1]) in Germany with third-generation CD19-directed CAR T cells.Methods and analysisAdult patients with r/r ALL (stratum I), r/r NHL including chronic lymphocytic leukaemia, diffuse large B-cell lymphoma, follicular lymphoma or mantle cell lymphoma (stratum II) as well as paediatric patients with r/r ALL (stratum III) will be treated with autologous T-lymphocytes transduced by third-generation RV-SFG.CD19.CD28.4-1BB zeta retroviral vector (CD19.CAR T cells). The main purpose of this study is to evaluate safety and feasibility of escalating CD19.CAR T cell doses (1–20×106transduced cells/m2) after lymphodepletion with fludarabine (flu) and cyclophosphamide (cyc). Patients will be monitored for cytokine release syndrome (CRS), neurotoxicity, i.e. CAR-T-cell-related encephalopathy syndrome (CRES) and/or other toxicities (primary objectives). Secondary objectives include evaluation ofin vivofunction and survival of CD19.CAR T cells and assessment of CD19.CAR T cell antitumour efficacy.HD-CAR-1 as a prospective, monocentric trial aims to make CAR T cell therapy accessible to patients in Europe. Currently, HD-CAR-1 is the first and only CAR T cell IIT in Germany. A third-generation Good Manufacturing Practice (GMP) grade retroviral vector, a broad spectrum of NHL, treatment of paediatric and adult ALL patients and inclusion of patients even after allogeneic stem cell transplantation (alloSCT) make this trial unique.Ethics and disseminationEthical approval and approvals from the local and federal competent authorities were granted. Trial results will be reported via peer-reviewed journals and presented at conferences and scientific meetings.Trial registration numberEudra CT 2016-004808-60;NCT03676504; Pre-results.

CD56bri natural killer (NK) cells play an important role in the pathogenesis of graft-vs. -host disease (GVHD) and immune defense in the early period after allogeneic hematopoietic stem cell transplantation. Extracorporeal photopheresis (ECP) as an immunomodulating therapy has been widely used for GVHD treatment. However, the mechanism of action of ECP still remains to be elucidated, particularly the influence of ECP on NK cells. Thirty-four patients with steroid-refractory/resistant acute GVHD (aGVHD) ≥ °II and moderate to severe chronic GVHD (cGVHD) received ECP therapy. Patient samples obtained during intensive and long-term treatment were analyzed. Immunomonitoring with respect to cell phenotype and function was performed on rested peripheral blood mononuclear cells (PBMCs) using multiparametric flow cytometry. NK activity in terms of cytokine release was analyzed by intracellular cytokine staining after co-culture with K562 cells. Moreover, the proliferative capacity of NK cells, CD4+, and CD8+ T cells was determined by carboxyfluorescein succinimidyl ester (CFSE) staining. Clinically, 75% of aGVHD and 78% of cGVHD patients responded to ECP therapy. Moreover, our data show that aGVHD, cGVHD patients and healthy donors (HDs) present distinct NK patterns: aGVHD patients have a higher frequency of CD56bri NK subsets with stronger NKG2D and CD62L expression, while CD56−CD16+ NK cells with higher expression of CD57 and CD11b stand out as a signature population for cGVHD. ECP therapy could significantly decrease CD56briCD16− NK cells with shifting the quality from a cytotoxic to a regulatory pattern and additionally mature CD56dim NK cells via upregulation of CD57 in complete responding aGVHD patients. Moreover, ECP could keep the anti-viral and anti-leukemic effects intact via maintaining specialized anti-viral/leukemic CD57+NKG2C+CD56dim NK cells as well as remaining the quality and quantity of cytokine release by NK cells. The proliferative capacity of effector cells remained constant over ECP therapy. In conclusion, ECP represents an attractive option to treat GVHD without compromising anti-viral/leukemic effects. Shaping of CD56bri NK cell compartment by downregulating the cytotoxic subset while upregulating the regulatory subset contributes to the mechanisms of ECP therapy in aGVHD.

As new generations of targeted therapies emerge and tumor genome sequencing discovers increasingly comprehensive mutation repertoires, the functional relationships of mutations to tumor phenotypes remain largely unknown. Here, we measured ex vivo sensitivity of 246 blood cancers to 63 drugs alongside genome, transcriptome, and DNA methylome analysis to understand determinants of drug response. We assembled a primary blood cancer cell encyclopedia data set that revealed disease-specific sensitivities for each cancer. Within chronic lymphocytic leukemia (CLL), responses to 62% of drugs were associated with 2 or more mutations, and linked the B cell receptor (BCR) pathway to trisomy 12, an important driver of CLL. Based on drug responses, the disease could be organized into phenotypic subgroups characterized by exploitable dependencies on BCR, mTOR, or MEK signaling and associated with mutations, gene expression, and DNA methylation. Fourteen percent of CLLs were driven by mTOR signaling in a non-BCR-dependent manner. Multivariate modeling revealed immunoglobulin heavy chain variable gene (IGHV) mutation status and trisomy 12 as the most important modulators of response to kinase inhibitors in CLL. Ex vivo drug responses were associated with outcome. This study overcomes the perception that most mutations do not influence drug response of cancer, and points to an updated approach to understanding tumor biology, with implications for biomarker discovery and cancer care.

T-cell prolymphocytic leukemia (T-PLL) is a rare and aggressive neoplasm of mature T-cells with an urgent need for rationally designed therapies to address its notoriously chemo-refractory behavior. The median survival of T-PLL patients is

We report on an improved method of synthesis of N-benzylaminoferrocene-based prodrugs and demonstrate its applicability by preparing nine new aminoferrocenes. Their effect on the viability of selected cancer cells having different p53 status was studied. The obtained data are in agreement with the hypothesis that the toxicity of aminoferrocenes is not dependent upon p53 status. Subsequently the toxicity of a selected prodrug (4) was investigated ex vivo using rat precision cut liver slices and in vivo on hybrid male mice BDF1. In both experiments no toxicity was observed: ex vivo, up to 10 μM; in vivo, up to 6 mg/kg. Finally, prodrug 4 was shown to extend the survival of BDF1 mice carrying L1210 leukemia from 13.7 ± 0.6 days to 17.5 ± 0.7 days when injected daily 6 times at a dose of 26 μg/kg starting from the second day after injection of L1210 cells.

Mutations of the tumor suppressor p53 lead to chemotherapy resistance and a dismal prognosis in chronic lymphocytic leukemia (CLL). Whereas p53 targets are used to identify patient subgroups with impaired p53 function, a comprehensive assessment of non-coding RNA targets of p53 in CLL is missing. We exploited the impaired transcriptional activity of mutant p53 to map out p53 targets in CLL by small RNA sequencing. We describe the landscape of p53-dependent microRNA/non-coding RNA induced in response to DNA damage in CLL. Besides the key p53 target miR-34a, we identify a set of p53-dependent microRNAs (miRNAs; miR-182-5p, miR-7-5p and miR-320c/d). In addition to miRNAs, the long non-coding RNAs (lncRNAs) nuclear enriched abundant transcript 1 (NEAT1) and long intergenic non-coding RNA p21 (lincRNA-p21) are induced in response to DNA damage in the presence of functional p53 but not in CLL with p53 mutation. Induction of NEAT1 and lincRNA-p21 are closely correlated to the induction of cell death after DNA damage. We used isogenic lymphoma cell line models to prove p53 dependence of NEAT1 and lincRNA-p21. The current work describes the p53-dependent miRNome and identifies lncRNAs NEAT1 and lincRNA-p21 as novel elements of the p53-dependent DNA damage response machinery in CLL and lymphoma.

Mutations in the N-terminus of MED12 protein occur at high frequency in uterine leiomyomas and breast fibroepithelial tumours, and are frequently found in chronic lymphocytic leukaemia (CLL). MED12 mutations have been previously linked to aberrant Cyclin C-CDK8 kinase activity, but the exact oncogenic function in CLL is unknown. Here, we characterized MED12 mutations in CLL and identified recurrent mutations in 13 out of 188 CLL patients (6·9%), which clustered in the N-terminus. MED12 mutations were associated with unmutated IGHV (P = 0·024). Protein analysis of NOTCH1 in primary CLL samples revealed increased levels of NOTCH1 intracellular domain (NICD), the active form of NOTCH1, in the context of MED12 mutations. We found evidence that NICD is the target of Cyclin C-CDK8 kinase using a specific CDK8 inhibitor. In line with these findings, MED12 mutations were mutually exclusive to mutations in NOTCH1 in CLL, based on a meta-analysis of 1429 CLL patients (P = 0·011). Our results suggest that MED12 mutations may contribute to CLL pathogenesis by activating NOTCH signalling.

Introduction T cells transduced with a chimeric antigen receptor (CAR) have demonstrated significant clinical efficacy in patients with lymphoid malignancies including relapsed or refractory (r/r) B-lineage acute lymphoblastic leukemia (ALL) or r/r B-cell non-Hodgkin's lymphoma (NHL). Second-generation CAR T cells comprising 4-1BB or CD28 as costimulatory domains have become commercially available for the treatment of patients with CD19+ lymphoid malignancies. However, achievement of durable clinical responses remains a challenge in CAR T cell therapy. Consequently, third-generation CARs incorporating both elements might display short-term efficacy with potent and rapid tumor elimination (CD28) as well as long-term persistence (4-1BB). So far, only two clinical trials employing third-generation CAR T cells have been reported. Both enrolled 31 patients in summary and demonstrated favorable results for third-generation CAR T cells. Here, we report on first results of our investigator-initiated trial (IIT) on third-generation CD19-directed CAR T cells: The Heidelberg CAR trial 1 (HD-CAR-1; NCT03676504; EudraCT 2016-004808-60) is a phase I/II trial initiated in September 2018 with in-house leukapheresis and CAR T cell manufacturing in full compliance with European Good Manufacturing Practice (GMP) guidelines at the University Hospital Heidelberg. Methods Adult and pediatric patients with r/r ALL and patients with r/r chronic lymphocytic leukemia (CLL) or NHL including diffuse large B-cell lymphoma (DLBCL), follicular lymphoma (FL) or mantle cell lymphoma (MCL) are treated with autologous T lymphocytes transduced with a CD19 targeting third-generation CAR retroviral vector (RV-SFG.CD19.CD28.4-1BBzeta). The main purpose of HD-CAR-1 is to evaluate safety and feasibility of escalating third-generation CAR T cell doses (1-20×106 transduced cells/m2) after lymphodepletion with fludarabine (30 mg/m2/d on days -4 to -2) cyclophosphamide (500 mg/m2/d on days -4 to -2). Patients are monitored for cytokine release syndrome (CRS), immune effector cell-associated neurotoxicity syndrome (ICANS) and/or other toxicities. In vivo function, survival and anti-tumor efficacy of CAR T cells are assessed. Results To date, 10 patients (3 adult ALL, 2 CLL, 2 MCL, 2 DLBCL, 1 transformed FL) have been enrolled and subjected to leukapheresis. Transduction efficiency of T lymphocytes ranged between 33%-66% and high numbers of transduced CAR T cells were harvested (70-123x106 CAR T cells). No production failure occurred. CAR T cell products were sterile and free from mycoplasma and endotoxins. The copy number per CAR T cell did not exceed 7. Eight patients (2 adult ALL, 2 CLL, 1 MCL, 2 DLBCL, 1 transformed FL) have received the CAR T cell product (6 patients: 106 transduced cells/m2; 2 patients 5×106 transduced cells/m2). No signs of CRS or ICANS > grade 2 have been observed. Only one patient required tocilizumab. No neurological side-effects occurred, even not in patients with involvement of the central nervous system (CNS). In quantitative real-time PCR, CAR T cells were detectable in the peripheral blood (PB) in 3 of 4 analyzed patients or the cerebrospinal fluid (CSF) of an ALL patient with CNS involvement. The CAR T cell frequency reached up to 200,000 copies/µg DNA, in some patients beyond end-of-study at day 90 after CAR T cell administration. Clinical responses to treatment were observed in 6/8 (75%) treated patients so far (2/8 patients have received CAR T cells recently and are not yet evaluable for response). Conclusion Leukapheresis and CAR T cell manufacturing were effective for all patients enrolled in the HD-CAR trial to date. Patients responded clinically to treatment despite low numbers of administered CAR T cells. CAR T cells displayed an excellent safety profile and were detectable for more than 3 months following administration. Furthermore, CAR T cells migrated into different compartments including the CSF in case of CNS involvement. For HD-CAR-1 leukapheresis, CAR T cell manufacturing, CAR T cell administration, patient monitoring and follow-up are performed in-house, providing autarky from transport or production sites outside the University Hospital Heidelberg. Altogether, HD-CAR-1 accounts to clinical evaluation of third-generation CAR T cells that might contribute to long-term CAR T cell persistence, hence improving efficient and durable responses in treated patients. Disclosures Schmitt: Therakos Mallinckrodt: Other: Financial Support . Sellner:Takeda: Employment. Müller-Tidow:MSD: Membership on an entity's Board of Directors or advisory committees. Dreger:AbbVie, AstraZeneca, Gilead, Janssen, Novartis, Riemser, Roche: Consultancy; AbbVie, Gilead, Novartis, Riemser, Roche: Speakers Bureau; Neovii, Riemser: Research Funding; MSD: Membership on an entity's Board of Directors or advisory committees, Other: Sponsoring of Symposia. Schmitt:Therakos Mallinckrodt: Other: Financial Support; MSD: Membership on an entity's Board of Directors or advisory committees, Other: Sponsoring of Symposia.

While recurrent mutations in CLL have been extensively catalogued, how driver mutations affect disease phenotypes remains incompletely understood. To address this, we performed RNA sequencing on 184 CLL patient samples and linked gene expression changes to molecular subgroups, gene mutations and copy number variants. Library preparation was performed according to the Illumina TruSeq RNA sample preparation v2 protocol. Samples were paired-end sequenced and two to three samples were multiplexed per lane on Illumina HiSeq 2000, Illumina HiSeq3000/4000 or Illumina HiSeqX machines. Raw RNA-seq reads were demultiplexed and quality control was performed using FastQC version 0.11.5. Internal trimming with STAR version 2.5.2a was used to remove adapters before mapping. Mapping was performed using STAR version 2.5.2a against the Ensembl human reference genome release 75 (Homo sapiens GRCh37.75). STAR was run in default mode with internal adapter trimming using the clip3pAdapterSeq option. Mapped reads were summarized into counts using htseq-count version 0.9.0 with default parameters and union mode. Thus, only fragments unambiguously overlapping with one gene were counted. The count data were then imported into R (version 3.4) for subsequent analysis. We identified robust and previously unknown gene expression signatures associated with recurrent copy number variants (including trisomy 12, del11q22.3, del17p13, del18p12 and gain8q24), gene mutations (TP53, BRAF and SF3B1) and the mutation status of the immunoglobulin heavy-chain variable region (IGHV). The most profound gene expression changes were associated with IGHV, methylation groups and trisomy 12. We found evidence for a significant influence of CNVs beyond the gene dosage effect. In line with these observations, unsupervised clustering showed that these major biological subgroups form distinct clusters and are discernible by unsupervised clustering (IGHV, methylation groups and trisomy 12). We found 3275 genes significantly differentially expressed between M-CLL and U-CLL after adjustment for multiple testing using the method of Benjamini and Hochberg for FDR = 1% . In total 9.5 % of variance within gene expression was associated with the IGHV status. These data suggest a much larger impact on transcriptional changes than previously detected (Ferreira et al. 2014), a finding much more in line with the key impact of IGHV on clinical course and biology of disease. We found distinct expression pattern of up- and downregulated genes for trisomy 12 samples. Even though many upregulated genes are located on chromosome 12, the majority of differentially expressed genes are indeed distributed among the other chromosomes and cannot be therefore not be ascribed to a simple gene dosage effect. To investigate the role of genetic interactions, we tested the collaborative effect on gene expression phenotypes. We investigated epistatic gene expression changes for IGHV status and trisomy 12. Epistasis was defined as a non-linear effect on gene expression between sample with both variants co-occuring and the single variants alone. In total 893 genes showed specific expression pattern in a combined genotype (padj In summary, our study provides a comprehensive reference data set for gene expression in CLL. We show that IGHV mutation status, recurrent gene mutations and CNVs drive gene expression in a previously underappreciated fashion. This includes epistatic interaction between trisomy 12 and IGHV. Using a novel way to describe coordinated changes we can group genes into sets related to buffering, inversion and suppression. Disclosures Sellner: Takeda: Employment.

Chronic lymphocytic leukemia (CLL) is an incurable malignancy of mature B cells. One of the major challenges in treatment of CLL is the achievement of a complete remission to prevent relapse of disease originating from cells within lymphoid tissues and subsequent chemoresistance. In search for novel drugs that target CLL cells in protective microenvironments, we performed a fungal extract screen using cocultures of primary CLL cells with bone marrow-derived stromal cells. A secondary metabolite produced by Penicillium aquamarinium was identified as Chaetoglobosin A (ChA), a member of the cytochalasan family that showed preferential induction of apoptosis in CLL cells, even under culture conditions that mimic lymphoid tissues. In vitro testing of 89 CLL cases revealed effective targeting of CLL cells by ChA, independent of bad prognosis characteristics, like 17p deletion or TP53 mutation. To provide insight into its mechanism of action, we showed that ChA targets filamentous actin in CLL cells and thereby induces cell-cycle arrest and inhibits membrane ruffling and cell migration. Our data further revealed that ChA prevents CLL cell activation and sensitizes them for treatment with PI3K and BTK inhibitors, suggesting this compound as a novel potential drug for CLL.

BACKGROUND Therapeutic options for patients with recurrent multiple myeloma after autologous stem cell transplantation (ASCT) include novel agents, conventional chemotherapy, or salvage ASCT with no standard of care. METHODS A total of 200 patients with multiple myeloma who developed disease recurrence after treatment with upfront ASCT and received an autologous retransplantation as salvage therapy at the study center over a period of 15 years were retrospectively reviewed. The objective of the current study was to evaluate the role of salvage ASCT in terms of efficacy, particularly taking into account the impact of novel agents. RESULTS The median progression-free survival (PFS) and overall survival after salvage ASCT were 15.2 months and 42.3 months, respectively. The overall response rate (a partial response or greater) was 80.4% at day 100, excluding 6 patients who died before assessment. Factors associated with improved PFS and overall survival after salvage ASCT included an initial PFS of > 18 months after upfront ASCT, bortezomib-containing or lenalidomide-containing therapies for reinduction, response to reinduction, and an International Staging System stage of I before salvage ASCT. CONCLUSIONS Salvage ASCT is capable of achieving sustained disease control in patients with multiple myeloma. The use of lenalidomide and bortezomib for reinduction has improved the results after salvage ASCT, suggesting that novel agents and salvage ASCT are complementary rather than alternative treatment approaches. Cancer 2013;119:2438-2446. © 2013 American Cancer Society.

Novel therapies with chimeric antigen receptor (CAR)-transduced T cells (TCs) sparked new hope for patients with relapsed or refractory CD19-positive leukemia or lymphoma even after stem cell therapies. This review focuses on CARs recognizing the B cell antigen CD19. Both retroviral and lentiviral vectors are used, encoding various anti-CD19 CAR constructs comprising costimulatory molecules such as CD28, CD137/4-1BB, and OX40 either alone (second-generation CARs) or in combination (third-generation CARs). Current, up-to-date published studies on anti-CD19 CAR therapy for acute lymphoblastic leukemia (ALL), chronic lymphocytic leukemia (CLL), and non-Hodgkin lymphoma (NHL) with observed side effects are discussed and an outlook on 58 ongoing trials is given. Clinical responses were achieved in up to 81% of ALL, 50% of CLL, and 40% of NHL patients. Factors with potential influence on the clinical outcome might be the design of the vector, the preconditioning regimen, and the number and quality of transfused CAR TCs. The applicability of clinical CAR TC therapy might include relapse after allogeneic stem cell transplantation (alloSCT), and ineligibility for or "bridging" until alloSCT. In summary, CAR therapy represents a highly promising treatment option even in heavily pretreated patients.

International audience; Clinical information about thiotepa-based autologous stem cell transplantation (auto-SCT) outside the primary central nervous system lymphoma (PCNSL) field is sparse. In this registry-based retrospective study, we evaluated potential risks and benefits of thiotepa-based preparative regimens compared with BEAM (carmustine, etoposide, cytarabine, melphalan) in auto-SCT for diffuse large B-cell lymphoma (DLBCL, excluding PCNSL), follicular lymphoma (FL) or Hodgkin lymphoma (HL). A total of 14 544 patients (589 thiotepa and 13 955 BEAM) met the eligibility criteria, and 535 thiotepa- and 1031 BEAM-treated patients were matched in a 1:2 ratio for final comparison. No significant differences between thiotepa and BEAM groups for any survival end point were identified in the whole sample or disease entity subsets. For a more detailed analysis, 47 TEAM (thiotepa, etoposide, cytarabine, melphalan)-treated patients were compared with 75 matched BEAM patients with additional collection of toxicity data. Again, there were no significant differences between the two groups for any survival end point. In addition, the frequency of common infectious and non-infectious complications including secondary malignancies was comparable between TEAM and BEAM. These results indicate that thiotepa-based high-dose therapy might be a valuable alternative to BEAM in DLBCL, HL and FL. Further evaluation by prospective clinical trials is warranted

Introduction: Graft-versus-host disease (GvHD), a severe complication of allogeneic hematopoietic stem cell transplantation (allo-HSCT), results in post-transplant morbidity and mortality. Steroids with strong immunosuppressive and anti-inflammatory effects remain the gold standard for initial management of GvHD. However, high doses of steroids are usually accompanied by an increased risk of infections and secondary malignancies. ECP, due to its good clinical response, is recommended as a second-line treatment for GvHD. Notably, no clinical data showed that ECP therapy results in relapse and infection. However, the mechanism of action behind that is barely known. Therefore, we conducted this study to figure out how ECP preserves the anti-viral and anti-leukemia effects. Materials and Methods: 34 patients with steroid-refractory/resistant aGvHD ≥ °II and moderate to severe cGvHD received ECP therapy at the University Hospitals Heidelberg, Greifswald and Tel Hashomer. ECP therapy was performed according to the current European guidelines. For clinical staging of aGvHD under ECP treatment patients were evaluated according to Glucksberg criteria, for quality of life according to Karnofsky and for clinical staging of cGvHD according to NIH criteria. Phenotypical analysis of different cellular subsets was evaluated by multicolor flow cytometry. The quantity and quality of virus-specific CD8+ T cells were evaluated by Tetramer staining and IFN-γ-ELISPOT. NK activity in terms of killing function and cytokine release function was monitored by chromium-51 release assay and intracellular cytokine staining. Results: ECP seems to be favorable in the treatment of GvHD. Clinically, an overall response of 75% for aGvHD and 78% for cGvHD patients was achieved. A steroid-sparing effect in addition to the resolution of GvHD manifestations was observed in responders. Our patients showed no increased susceptibility to infections. On the cellular level, the frequency of cytotoxic CD8+ T cells, the most important mediators of GvL activity, as well as CD4+CD8+ T cells, γδ T cells, NKT cells and CD56dimCD57+NKG2C+ NK cells as other well-established protective cell subsets remained constant under ECP therapy. Moreover, neither frequency nor IFN-γ release of CMV specific CD8+ T cells was hampered by ECP. 51Cr-release assay revealed stable functional cytotoxicity of NK cells. Additionally, ECP therapy did not affect the capacity of cytokine release by NK cells, including quality, quantity and multifunctional release. Furthermore, no significant influence of ECP therapy on antigen recall function of NK cells, CD4+ and CD8+ T cells could be observed. Conclusion: ECP therapy represents an attractive strategy to treat GvHD. Moreover, our results reflect that ECP therapy preserves immunity against infections as well as the GvL effect via maintaining the quality and quantity of effector cells. Disclosures Hilgendorf: Novartis: Other: Travel support, Research Funding; Medac: Other: Travel support, Research Funding.

Background and aims. Because of their pluripotency, human CD34 peripheral blood progenitor cells (PBPC) are targets of interest for the treatment of many acquired and inherited disorders using gene therapeutic approaches. Unfortunately, most current vector systems lack either suffi cient transduction effi ciency or an appropriate safety profi le. Standard single-stranded recombinant adeno-associated virus 2 (AAV2)-based vectors offer an advantageous safety profi le, yet lack the required effi ciency in human PBPC. Methods. A panel of pseudotyped AAV vectors (designated AAV2/x, containing the vector genome of serotype 2 and capsid of serotype x, AAV2/1–AAV2/6) was screened on primary human granulocyte–colony-stimulating factor (G-CSF)-mobilized CD34 PBPC to determine their gene transfer effi cacy. Additionally, double-stranded selfcomplementary AAV (dsAAV) were used to determine possible second-strand synthesis limitations. Results. AAV2/6 vectors proved to be the most effi cient [12.8% (1.8–25.4%) transgene-expressing PBPC after a single transduction], being signifi cantly more effi cient (all P0.005) than the other vectors [AAV2/2, 2.0% (0.2–7.3%); AAV2/1, 1.3% (0.1–2.9%); others, 1% transgene-expressing PBPC]. In addition, the relevance of the single-to-double-strand conversion block in transduction of human PBPC could be shown using pseudotyped dsAAV vectors: for dsAAV2/2 [9.3% (8.3–20.3%); P0.001] and dsAAV2/6 [37.7% (23.6–61.0%); P0.001) signifi cantly more PBPC expressed the transgene compared with their singlestranded counterparts; for dsAAV2/1, no signifi cant increase could be observed. Conclusions. We have shown that clinically relevant transduction effi ciency levels using AAV-based vectors in human CD34 PBPC are feasible, thereby offering an effi cient alternative vector system for gene transfer into this important target cell population.

Complement-dependent cytotoxicity (CDC) is one of the effector mechanisms mediated by therapeutic anticancer monoclonal antibodies (mAbs). However, the efficacy of antibodies is limited by the resistance of malignant cells to complement attack, primarily due to the over-expression of one or more membrane complement regulatory proteins (mCRPs) CD46, CD55, and CD59. CD20-positive Burkitt lymphoma Raji cells and primary CLL cells are resistant to rituximab (RTX)-induced CDC whereas ofatumumab (OFA) proved to be more efficient in cell killing. Primary CLL cells but not CD52-positive acute lymphoblastic leukemia (ALL) REH cells were sensitive to alemtuzumab (ALM)-induced CDC. Upon combined inhibition on Raji and CLL cells by mCRPs-specific siRNAs or neutralizing antibodies, CDC induced by RTX and by OFA was augmented. Similarly, CDC of REH cells was enhanced after mCRPs were inhibited upon treatment with ALM. All mAbs induced C3 opsonization, which was significantly augmented upon blocking mCRPs. C3 opsonization led to enhanced cell-mediated cytotoxicity of leukemia cells exposed to PBLs or macrophages. Furthermore, opsonized CLL cells were efficiently phagocytized by macrophages. Our results provide conclusive evidence that inhibition of mCRPs expression sensitizes leukemic cells to complement attack thereby enhancing the therapeutic effect of mAbs targeting leukemic cells.