The antibody-drug conjugate polatuzumab vedotin (pola) has recently been approved in combination with bendamustine and rituximab (pola-BR) for patients with refractory or relapsed (r/r) large B-cell lymphoma (LBCL). To investigate the efficacy of pola-BR in a real-world setting, we retrospectively analyzed 105 patients with LBCL who were treated in 26 German centers under the national compassionate use program. Fifty-four patients received pola as a salvage treatment and 51 patients were treated with pola with the intention to bridge to chimeric antigen receptor (CAR) T-cell therapy (n = 41) or allogeneic hematopoietic cell transplantation (n = 10). Notably, patients in the salvage and bridging cohort had received a median of 3 prior treatment lines. In the salvage cohort, the best overall response rate was 48.1%. The 6-month progression-free survival and overall survival (OS) was 27.7% and 49.6%, respectively. In the bridging cohort, 51.2% of patients could be successfully bridged with pola to the intended CAR T-cell therapy. The combination of pola bridging and successful CAR T-cell therapy resulted in a 6-month OS of 77.9% calculated from pola initiation. Pola vedotin-rituximab without a chemotherapy backbone demonstrated encouraging overall response rates up to 40%, highlighting both an appropriate alternative for patients unsuitable for chemotherapy and a new treatment option for bridging before leukapheresis in patients intended for CAR T-cell therapy. Furthermore, 7 of 12 patients with previous failure of CAR T-cell therapy responded to a pola-containing regimen. These findings suggest that pola may serve as effective salvage and bridging treatment of r/r LBCL patients.

Introduction The antibody-drug conjugate polatuzumab vedotin (Pola) has recently been approved in combination with bendamustine and rituximab (Pola-BR) for patients with r/r diffuse LBCL (DLBCL). Methods To characterize the efficacy of Pola-BR in a real-world setting, we retrospectively analyzed data from 97 patients with r/r LBCL who were treated with Pola in 24 German centers within the national CUP. Clinical baseline and follow-up (FU) data were collected by chart review and summarized descriptively. Progression-free survival (PFS) and overall survival (OS) were analyzed using Kaplan-Meier and Cox regression methods. Fisher's exact test was used to compare categorical factors between groups of patients. Results 97 patients with LBCL (DLBCL n=90, High-grade B-cell lymphoma n=6, Primary mediastinal B-cell lymphoma n=1) were included as of July 22nd, 2020. 49 patients were treated with Pola as bridging concept to immunotherapies (bridging cohort: chimeric antigen receptor T-cells (CART) n=39, allogeneic stem cell transplantation (alloSCT) n=9, bispecific antibodies n=1), and 48 patients were treated with Pola in palliative intention (palliative cohort). Within the bridging cohort the median age was 61 years (range: 22-82). Patients were heavily pretreated with a median of 3 treatment lines (range: 2-6). 84% (41/49 patients) had been refractory to their last treatment line, and 31% had failed an autologous stem cell transplantation. Notably, 14% and 10% of patients had failed prior CART and alloSCT, respectively, and were planned for the alternate cellular immunotherapy. Based on an individual decision, patients were treated with Pola-Rituximab (Pola-R, n=20), Pola-chemotherapy (Pola-chemo, BR n=25; R-CHP n=1) or Pola-monotherapy (Pola-mono, n=3). With a median of 2 Pola cycles (range 1-6), overall response rate (ORR) of all evaluable patients was 33% (15/46 patients) including patients with complete response (CR n=1), partial response (PR n=9) and clinical response (n=5). Although not significant, ORR tended to be better in patients treated with Pola-chemo versus Pola-R/Pola-mono (ORR: 42% versus 20%, Fishers test p=0.1). 11 of these 15 responders (24% of the entire bridging cohort) proceeded to CART or alloSCT, while 4 responders (8% of entire bridging cohort) experienced fast progression after their initial response and were referred to best supportive care. 15 of 31 non-responders (33% of entire bridging cohort) underwent immunotherapy with either stable disease (n=6), mixed response (n=2), or progression on Pola (n=7). The remaining 16 patients (35% of entire bridging cohort) were all refractory to Pola and either received alternative salvage treatments which enabled 8 further patients to proceed to the intended immunotherapy, or best supportive care. Taking the effects of CART or alloSCT into account, median OS from initiation of Pola treatment was 8.2 months (median FU 7.2 months, Fig. 1A). The palliative cohort tended to be older than the bridging cohort with a median age of 73.5 years (range: 37-86, p<0.001). Patients were pretreated with a median of 3 treatment lines (range: 2-8), and 85% (41/48 patients) had been refractory to their last treatment line. Patients in the palliative cohort were treated with a median of 4 Pola cycles (range: 1-9). 65% received Pola-chemo (BR, n=30; R-Gemcitabine, n=1) and 35% Pola-R. The CR rate and ORR was 19% (9/48) and 56% (27/48), respectively. The 6-month PFS and OS from initiation of Pola was 36% and 51%, respectively (median FU of 9.7 months, Fig. 1B). Again, ORR and OS tended to be better in patients treated with Pola-chemo versus Pola-R (ORR: 61% versus 47%, Fishers test p=0.4; median OS 7.2 versus 4 months, HR 0.8, 95%CI 0.4-1.9, p=0.7). In univariate analysis, failure to respond to the last treatment line predicted inferior PFS (HR 2.4, 95%CI 1.2-5.0 p=0.02) and OS (HR 2.5, 95%CI 1.2-5.4 p=0.02). Patients with more than two prior treatment lines in total tended to have a shorter PFS (HR 2.0, 95% CI 0.9-4.5, p=0.1) and OS (HR 1.8, 95% CI 0.8-4.0, p=0.2), although significance was not reached. Conclusion Pola permits effective bridging to CART and alloSCT in r/r LBCL. In the palliative setting, Pola represents an effective salvage option for patients with transplantation-ineligible r/r LBCL. Compared to the approval study, the inferior outcome of the patients of this real-world analysis might be explained by their more advanced disease course. Disclosures Duell: Morphosys: Research Funding. Kerkhoff:BMS: Honoraria. Leng:Roche: Other: lecture fee; Celgene: Other: traveling expenses and congress attendance fee. Holtick:Miltenyi Biotec B.V. & Co. KG: Honoraria. Mayer:Amgen: Honoraria, Other: travel grants; Abbvie: Other: travel grants; Novartis: Honoraria; Roche: Honoraria. Hüttmann:Celgene: Honoraria, Other: TRAVEL, ACCOMMODATIONS, EXPENSES (paid by any for-profit health care company); Gilead: Honoraria; Takeda: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: TRAVEL, ACCOMMODATIONS, EXPENSES (paid by any for-profit health care company); Roche: Other: Travel expenses; Seattle Genetics: Research Funding; University Hospital Essen, University of Duisburg-Essen, Essen, Germany: Current Employment; Lead Discovery Center GmbH: Consultancy. Brunnberg:Gilead: Membership on an entity's Board of Directors or advisory committees; Hexal: Membership on an entity's Board of Directors or advisory committees; Janssen: Membership on an entity's Board of Directors or advisory committees, Other: travel grants; MSD: Membership on an entity's Board of Directors or advisory committees; Roche: Membership on an entity's Board of Directors or advisory committees, Other: Travel grants; Amgen: Other: Travel grants. Bullinger:Menarini: Membership on an entity's Board of Directors or advisory committees; Gilead: Membership on an entity's Board of Directors or advisory committees; Amgen: Membership on an entity's Board of Directors or advisory committees; Pfizer: Membership on an entity's Board of Directors or advisory committees; Daiichi Sankyo: Membership on an entity's Board of Directors or advisory committees; Novartis: Membership on an entity's Board of Directors or advisory committees; Hexal: Membership on an entity's Board of Directors or advisory committees; Janssen: Membership on an entity's Board of Directors or advisory committees; Jazz Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees; Abbvie: Membership on an entity's Board of Directors or advisory committees; Seattle Genetics: Membership on an entity's Board of Directors or advisory committees; Sanofi: Membership on an entity's Board of Directors or advisory committees; Astellas: Membership on an entity's Board of Directors or advisory committees; Celgene: Membership on an entity's Board of Directors or advisory committees; Bristol-Myers Squibb: Membership on an entity's Board of Directors or advisory committees. Hess:Roche: Research Funding; Celgene: Research Funding; Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Genmab: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Gilead: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Astra: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Abbvie: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; EUSA: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Morphosys: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Mueller-Tidow:Pfizer: Membership on an entity's Board of Directors or advisory committees, Research Funding; Deutsche Krebshilfe: Research Funding; BMBF: Research Funding; Wilhelm-Sander-Stiftung: Research Funding; Jose-Carreras-Siftung: Research Funding; Bayer AG: Research Funding; Daiichi Sankyo: Research Funding; BiolineRx: Research Funding; Janssen-Cilag Gmbh: Membership on an entity's Board of Directors or advisory committees; Deutsche Forschungsgemeinschaft: Research Funding. Lenz:Verastem: Research Funding; AQUINOX: Research Funding; BMS: Consultancy; AstraZeneca: Consultancy, Honoraria, Research Funding; Bayer: Consultancy, Honoraria, Research Funding, Speakers Bureau; Agios: Research Funding; Gilead: Consultancy, Honoraria, Research Funding, Speakers Bureau; Roche: Consultancy, Honoraria, Research Funding, Speakers Bureau; Celgene: Consultancy, Honoraria, Speakers Bureau; Novartis: Consultancy; Morphosys: Consultancy, Honoraria, Research Funding; Janssen: Consultancy, Honoraria, Research Funding, Speakers Bureau. Dreger:Roche: Consultancy, Speakers Bureau; Neovii: Research Funding; AbbVie: Consultancy, Speakers Bureau; AstraZeneca: Consultancy; Gilead: Consultancy, Speakers Bureau; Janssen: Consultancy; Novartis: Consultancy, Speakers Bureau; Riemser: Consultancy, Research Funding, Speakers Bureau. Dietrich:Roche: Membership on an entity's Board of Directors or advisory committees; Janssen: 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; KITE: Membership on an entity's Board of Directors or advisory committees.

BACKGROUND:Graft-versus-host disease (GvHD) presents a major cause for morbidity and mortality after allogeneic hematopoietic stem cell transplantation. Rabbit-derived antithymocyte globulin (rATG) treatment reduces the incidence of GvHD after allogeneic hematopoietic stem cell transplantation. However, delayed immune reconstitution following rATG treatment, partly caused by hampered thymic function, is being discussed. The present study aims at elucidating possible cytotoxic effects of 2 commonly used rATG preparations on cultured human thymic stroma, especially thymic epithelial cells (TECs).METHODS:A primary TEC culture was established and the binding and cytotoxicity of 2 rATG preparations to the aforementioned cells were assessed by flow cytometry and immunofluorescence analyses. The release of several cytokines by cultured thymic stroma cells in response to rATG was analyzed via multiplex enzyme-linked immunosorbent assays.RESULTS:Both preparations showed a comparable dose-dependent binding to TECs and exerted a similar complement-independent, dose-dependent cytotoxicity. rATG exposure further resulted in hampered secretion of interleukin (IL)-7, IL-15, and IL-6, cytokines being involved in thymic T cell development and proliferation. Pretreatment with keratinocyte growth factor diminished rATG-induced cytotoxicity of TECs and restored their IL-7 and IL-15 secretion.CONCLUSIONS:Cytotoxic effects on TECs link the rATG-induced thymic damage to the delayed T cell reconstitution, witnessed after rATG treatment. Our data support a combination treatment of rATG and thymus-protective strategies such as keratinocyte growth factor to simultaneously offer sufficient GvHD prophylaxis and overcome delayed T cell reconstitution caused by thymic damage.

High-resolution magic angle spinning (HRMAS) MRS allows for direct measurements of non-liquid tissue and cell specimens to present valuable insights into the cellular metabolisms of physiological and pathological processes. HRMAS produces high-resolution spectra comparable to those obtained from solutions of specimen extracts but without complex metabolite extraction processes, and preserves the tissue cellular structure in a form suitable for pathological examinations following spectroscopic analysis. The technique has been applied in a wide variety of biomedical and biochemical studies and become one of the major platforms of metabolomic studies. By quantifying single metabolites, metabolite ratios, or metabolic profiles in their entirety, HRMAS presents promising possibilities for diagnosis and prediction of clinical outcomes for various diseases, as well as deciphering of metabolic changes resulting from drug therapies or xenobiotic interactions. In this review, we evaluate HRMAS MRS results on animal models and cell lines reported in the literature, and present the diverse applications of the method for the understanding of pathological processes and the effectiveness of therapies, development of disease animal models, and new progress in HRMAS methodology.