Abstract: Abstract 4183 Chronic GvHD (cGvHD) still remains a relevant problem after allogeneic stem cell transplantation (SCT), substantially contributing to morbidity and mortality of the procedure. Although manifestations of cGvHD in the genital organs of female patients are well recognized, only very few case reports regarding the involvement of male genital mucosa exist, resulting in the fact that in the organ system assessment forms generated by the NIH Chronic GVHD Consensus Group only female genital tract findings are included. In our observation male findings are present in daily practice if the patient is asked actively for genital problems. Therefore it seems to be a rather under-recognized manifestation of cGVHD. To estimate the prevalence of this problem we prospectively analyzed all male patients presenting in a five month period in our outpatient SCT-clinic for the presence of signs of cGvHD involvement of the genital mucosa or problems in the past. During 9/2010 – 1/2011 in total 250 male patients were seen for follow up after allogeneic SCT, eleven patients out of these (4,4 %) reported present or past signs of cGVHD of the genital mucosa. The clinical presentations varied widely and led from inflammatory processes with local irritation and pain to fibrosis and scarring of the prepuce and glans penis. Depending on their extent of involvement these findings resulted in a serious impact on quality of life and impaired sexual health in particular. In more detail, symptoms varied from: 1. mild inflammatory processes with erythematous changes of the glans (4/11– 36,6%); 2. extensive inflammatory processes with erythema and erosive changes (4/11– 36,6%); 3. phimoses (2/11–18,3%); 4. sclerodermoid processes with penile urethral strictures and urethral meatus stenosis (1/11–9%). In none of the patients any infectious pathogens responsible for the observed findings could be detected. Time between SCT and initial symptoms ranged from 6 months to 6 years after transplantation. Almost all patients with involvement of the genital mucosa showed signs of cGvHD in other mucosal sites, e.g. ocular/oral mucosa (10/11, 90,9%). Cutaneous cGVHD was present in 100%. Inflammatory processes responded mostly to antiinflammatory therapy with local steroid/topical tacrolimus. Since in the course of the disease 6/11 patients (54,5%) eventually developed phimoses, surgical intervention for this condition was required in 4 patients (66,6%). The patient with urethral strictures had a urethrotomy. For normal miction he still has to perform daily dilatations. In the few cases with mucosal biopsies histopatholology showed lichenoid changes (lymphohistiocytic infiltrates between epidermis and dermis with pigmentincontinence) fitting to inflammatory processes of cGvHD and fibrosis. In summary, the presented data implicate that patients after SCT need to be asked actively for genital problems since it is infrequently reported spontaneously. Special caution is required for patients with cutaneous or other mucosal (eyes/oral) cGvHD since they might have developed also unrecognized genital GVHD. Early and interdiscipilinary intervention is necessary to prevent phimoses and sclerodermoid stages as late manifestation. Disclosures: Bertz: Fresenius Biotech GmbH: Lecture remuneration Other.

Abstract: Patients with relapsed or refractory acute lymphoblastic leukemia (ALL) have a dismal prognosis. CD19 is homogenously expressed in B-precursor ALL and can be targeted by the investigational bispecific T cell–engager antibody blinatumomab. A phase II trial was performed to determine clinical activity in this patient cohort. Patients and Methods Thirty-six patients with relapsed or refractory B-precursor ALL were treated with blinatumomab in cycles of 4-week continuous infusion followed by a 2-week treatment-free interval in a single-arm study with a dose-finding stage and an extension stage. The primary end point was complete remission (CR) or CR with partial hematologic recovery (CRh). Major secondary end points included minimal residual disease (MRD) response, rate of allogeneic hematopoietic stem-cell transplantation (HSCT) realization, relapse-free survival (RFS), overall survival (OS), and incidence of adverse events (AEs). Results Median age was 32 years (range, 18 to 77 years). Twenty-five patients (69%) achieved a CR or CRh, with 88% of the responders achieving an MRD response. Median OS was 9.8 months (95% CI, 8.5 to 14.9), and median RFS was 7.6 months (95% CI, 4.5 to 9.5). Thirteen responders (52%) underwent HSCT after achieving a CR or CRh. The most frequent AE during treatment was pyrexia (grade 1 or 2, 75%; grade 3, 6%). In six patients with nervous system or psychiatric disorder AEs and in two patients with cytokine release syndrome, treatment had to be interrupted or discontinued. These medical events were resolved clinically. Conclusion The data support further investigation of blinatumomab for the treatment of adult patients with relapsed or refractory ALL in a larger confirmatory study.

Abstract: 7549 Background: Polatuzumab vedotin plus rituximab, cyclophosphamide, doxorubicin and prednisone (Pola-R-CHP) has shown a significant progression-free survival benefit versus R-CHOP as first line (1L) therapy for DLBCL (Tilly et al. 2022). Glofitamab is a bispecific antibody with a novel 2:1 (CD20:CD3) format; bivalency for CD20 on B cells enables combination with anti-CD20 antibodies, including rituximab. Glofitamab monotherapy induced durable responses in patients (pts) with relapsed/refractory DLBCL and its incorporation in the 1L setting may further improve outcomes (Dickinson et al. 2022). We present results from the expansion stage of an ongoing Phase Ib study (NCT03467373) of glofitamab (Glofit) + Pola-R-CHP in pts with 1L DLBCL. Methods: Pts received Pola-R-CHP on Day (D) 1 of each 21-day cycle (C; max. 6 cycles) and glofitamab in C2‒C6 (C2 step-up dosing [2.5mg C2D8, 10mg C2D15]; target dose [30mg] C3D8 and onwards). Response was assessed by PET-CT using Lugano criteria (Cheson et al. 2014). Efficacy-evaluable pts were those that reached end of treatment (EOT), progressed or died by data cut-off (EOT population). Cytokine release syndrome (CRS) events were graded by ASTCT criteria (Lee et al. 2019) and other adverse events (AEs) by CTCAE (v4.0). Results: As of Nov 14, 2022, 24 pts had enrolled and received study treatment (safety population). Median age was 65 years (range: 32–85), 96% of pts had stage III–IV disease and median IPI score was 3 (IPI 1: 4% [1/24], IPI 2: 33% [8/24] , IPI 3: 38% [9/24], IPI 4: 25% [6/24] ). Of 24 pts, 17 were efficacy evaluable. After a median follow up of 5.1 (range: 3–8) months, complete metabolic response rate was 76.5% (13/17) and overall response rate was 100% in the EOT population (best overall response). In safety-evaluable pts, Grade (Gr) ≥3 AEs occurred in 15 (63%) pts and Gr ≥3 AEs related to glofitamab in 9 (38%) pts. One Gr 5 AE was reported (acute respiratory distress syndrome, unrelated to study treatment). Serious AEs (SAEs) were reported in 12 (50%) pts and SAEs related to glofitamab in 4 (17%) pts. AEs leading to glofitamab dose interruption occurred in 5 (21%) pts; median dose intensity was 100% for all Glofit + Pola-R-CHP components. Only Gr 1 CRS (n = 3, 13%) was reported, with no treatment or hospitalization required. Neurological AEs (NAEs) occurred in 11 (46%) pts and were mostly Gr 1/2 (10 pts, 42%); one patient had a Gr 3 NAE (hypomania). No NAEs potentially consistent with immune effector cell-associated neurotoxicity syndrome were reported. Neutropenia was reported in 12 (50%) pts (Gr 3, n = 6; Gr 4, n = 6), febrile neutropenia in 2 (8.3%) pts and Gr 3/4 infection in 4 (17%) pts (Gr 3, n = 2; Gr 4, n = 2). Conclusions: Early data suggest that Glofit + Pola-R-CHP has promising efficacy and a similar safety profile to Pola-R-CHP and Glofit + R-CHOP for 1L DLBCL treatment. Glofit + Pola-R-CHP dose intensity was maintained in all pts. Updated data will be presented. Clinical trial information: NCT03467373 .

Abstract: Introduction Although the labeled CD19 targeting CAR-T cell constructs axi-cel and tisa-cel are generally associated with an acceptable safety profile, non-relapse deaths can occur. Little is known about timing, causes and predictors of NRM following SOC CAR-T cell therapy for LBCL. Here, we analyzed frequency, causes, and risk factors of non-relapse deaths with focus on late NRM (beyond 4 weeks after dosing) using registry data provided by the DRST, the national partner of the EBMT. Methods Patients were selected from 356 consecutive patients who received SOC CAR-T treatment of LBCL between November 2018 and April 2021 at 21 German centers and were registered with the DRST/EBMT. Baseline patient, disease, and transplant data were collected from MED-A cellular therapy forms. Centers were contacted to provide additional treatment and follow-up information. Patients with late NRM (defined as NRM occurring beyond 4 weeks after dosing without prior LBCL relapse or progression) were compared with all patients surviving progression-free the 4-week landmark after dosing without subsequent NRM. Cumulative incidences of NRM were calculated considering relapse/progression as competing event. Results The analysis set consisted of 312 patients surviving progression-free at least 28 days after CAR-T treatment and remained alive until the end of follow-up or had a documented cause of death. Median age was 61 years (19-83), 66% were male, 52% had an IPI ≥3, 13 had an ECOG score & gt;1, 70% had received ≥3 treatment lines, 33% had failed a prior HCT, and 78% were refractory at lymphodepletion. 50% had been treated at a center contributing ≥20 cases with axi-cel (52%) or tisa-cel (48%). Grade ≥3 CRS and grade ≥3 neurotoxicity (NT) had occurred in 11% each, and 7% had no neutrophil recovery at day 100 post dosing or at last follow-up, whatever was earlier. With a median follow-up of 11.2 months, 124 patients (40%) had died, 109 (35%) LBCL-related, and 15 (5%) because of NRM. The cumulative incidence of late NRM at 12 months post dosing was 4.3% (95%CI 2.0-6.6). Causes of NRM were infections in 10 patients (bacterial or fungal sepsis/pneumonia 6; viral/atypical pneumonia/encephalitis 4); late NT 2; hyperinflammatory syndrome 1; 2 nd malignancy 1; unknown 1). Of note, 5 of the 6 lethal fungal/bacterial infections occurred subsequent to high grade NT. There was no significant difference between patients experiencing and not experiencing NRM in terms of age, gender, IPI, ECOG, pretreatment lines, prior HCT, disease status at lymphodepletion, and grade ≥3 CRS frequency. However, a significantly larger proportion of patients with late NRM had failed neutrophil recovery (27% vs 5%, p 0.011), had experienced grade ≥3 NT (40% vs 10%, p 0.0031), and/or had received axi-cel (93% vs 51%, p 0.001). Patients having neutrophil non-recovery and/or grade ≥3 NT had a 12-month NRM incidence of 16% (95%CI 5.1-26.9) vs 2.5% (95%CI 0.3-4.7) in patients with none of these 2 factors. Conclusions Late NRM in patients receiving SOC CAR-T treatment for LBCL is largely driven by infections. Risk factors for late NRM appear to be protracted neutropenia and higher grade NT, suggesting that intensified anti-bacterial/anti-fungal prophylaxis may be considered in patients with persisting critical neutropenia or exposed to high-dose steroids for NT treatment. Figure 1 Figure 1. Disclosures Dreger: BMS: Consultancy; AstraZeneca: Consultancy, Speakers Bureau; Bluebird Bio: Consultancy; AbbVie: Consultancy, Speakers Bureau; Gilead Sciences: Consultancy, Speakers Bureau; Janssen: Consultancy; Novartis: Consultancy, Speakers Bureau; Riemser: Consultancy, Research Funding, Speakers Bureau; Roche: Consultancy, Speakers Bureau. Schubert: Gilead: Consultancy. Holtick: Sanofi: Honoraria; Celgene: Honoraria. Subklewe: Miltenyi: Research Funding; Takeda: Speakers Bureau; Gilead: Consultancy, Research Funding, Speakers Bureau; Klinikum der Universität München: Current Employment; MorphoSys: Research Funding; Novartis: Consultancy, Research Funding, Speakers Bureau; Roche: Research Funding; Seattle Genetics: Consultancy, Research Funding; Pfizer: Consultancy, Speakers Bureau; Janssen: Consultancy; BMS/Celgene: Consultancy, Research Funding, Speakers Bureau; Amgen: Consultancy, Research Funding, Speakers Bureau. Bastian: Abbvie: Other; Amgen: Consultancy, Honoraria; Astra Zeneca: Honoraria, Other; BMS and Celgene: Consultancy, Honoraria, Other; Kite-Gilead: Consultancy, Honoraria; MSD: Consultancy, Honoraria, Other, Research Funding; Novartis: Consultancy, Honoraria, Other, Research Funding; Pentixafarm: Consultancy, Honoraria; Pfizer: Consultancy, Honoraria; Roche: Consultancy, Honoraria; Takeda: Consultancy, Honoraria, Other, Research Funding. Ayuk: Gilead: Honoraria; Celgene/BMS: Honoraria; Janssen: Honoraria; Takeda: Honoraria; Miltenyi Biomedicine: Honoraria; Mallinckrodt/Therakos: Honoraria, Research Funding; Novartis: Honoraria. Marks: Kite/Gilead: Membership on an entity's Board of Directors or advisory committees; Kite/Gilead: Honoraria; Merck: Consultancy; AbbVie: Other: Meeting attendance. Penack: Priothera: Consultancy; Takeda: Research Funding; Incyte: Research Funding; Neovii: Honoraria; Pfizer: Honoraria; Therakos: Honoraria; Novartis: Honoraria; MSD: Honoraria; Jazz: Honoraria; Gilead: Honoraria; Astellas: Honoraria; Shionogi: Consultancy; Omeros: Consultancy. Koenecke: EUSA Pharm: Consultancy; Kite/Gilead: Consultancy; BMS/Celgene: Consultancy; Janssen: Consultancy; Novartis: Consultancy. Von Bonin: Daiichi Sankyo: Other: traveling support and advisory fees; Novartis: Other: traveling support and advisory fees; Kite/Gilead: Other: traveling support and advisory fees. Stelljes: Novartis: Consultancy, Speakers Bureau; MSD: Consultancy, Speakers Bureau; Pfizer: Consultancy, Research Funding, Speakers Bureau; Amgen: Consultancy, Speakers Bureau; Medac: Speakers Bureau; Celgene/BMS: Consultancy, Speakers Bureau; Kite/Gilead: Consultancy, Speakers Bureau. Glass: BMS: Consultancy; Helios Klinik Berlin-Buch: Current Employment; Kite: Consultancy; Novartis: Consultancy; Riemser: Research Funding; Roche: Consultancy, Research Funding, Speakers Bureau. Baldus: Novartis: Honoraria; Amgen: Honoraria; Celgene/BMS: Honoraria; Jazz: Honoraria. Vucinic: MSD: Honoraria; Novartis: Honoraria; Gilead: Honoraria, Other: Travel Sponsoring; Janssen: Honoraria, Other: Travel Sponsoring; Abbvie: Honoraria, Other: Travel Sponsoring. Topp: Universitatklinikum Wurzburg: Current Employment; Celgene: Consultancy, Research Funding; Janssen: Consultancy; Kite, a Gilead Company: Consultancy, Research Funding; Novartis: Consultancy; Roche: Consultancy, Research Funding; Gilead: Research Funding; Regeneron: Consultancy, Research Funding; Macrogeniecs: Research Funding; Amgen: Consultancy, Research Funding. Schroers: BMS/Celgene: Consultancy, Honoraria; Janssen: Consultancy, Honoraria; GSK: Consultancy, Honoraria; Takeda: Honoraria. Hanoun: AstraZeneca: Honoraria; Abbvie: Other: travel expenses; Novartis: Research Funding. Thomas: AbbVie: Honoraria, Speakers Bureau; Art tempi: Honoraria, Speakers Bureau; BMS/Celgene: Consultancy, Honoraria, Other, Research Funding, Speakers Bureau; EUSA Pharma: Consultancy, Honoraria; Janssen: Consultancy, Honoraria, Other; Kite/Gilead: Honoraria, Other, Research Funding, Speakers Bureau; Medigene: Consultancy, Honoraria, Other; Novartis: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other; Pfizer: Consultancy, Honoraria, Other, Speakers Bureau. Kröger: Novartis: Research Funding; Riemser: Honoraria, Research Funding; Sanofi: Honoraria; Neovii: Honoraria, Research Funding; Jazz: Honoraria, Research Funding; Gilead/Kite: Honoraria; Celgene: Honoraria, Research Funding; AOP Pharma: Honoraria. Bethge: Novartis: Consultancy, Honoraria, Speakers Bureau; Miltenyi Biotec: Consultancy, Honoraria, Research Funding, Speakers Bureau; Kite-Gilead: Consultancy, Honoraria, Speakers Bureau; Janssen: Consultancy, Honoraria, Speakers Bureau; Celgene: Consultancy, Honoraria, Speakers Bureau.

Abstract: Several cytoplasmic proteins, such as GTPases of the Ras family, containing a C-terminal CAAX motif are prenylated by farnesyltransferase to facilitate localization to cellular membranes where activation occurs. Farnesyltransferase inhibitors (FTIs) interfere with this farnesylation process, thereby preventing proper membrane localization and rendering the proteins unavailable for activation. Currently, FTIs are being explored as antineoplastic agents for the treatment of several malignancies. However, since farnesylated proteins like Ras are also involved in intracellular signaling in lymphocytes, FTIs might interfere with T-cell activation. Based on this hypothesis we examined the effect of several FTIs on cytokine production in response to anti-CD3 + anti-CD28 monoclonal antibodies or PMA + ionomycin. Murine Th1 and Th2 clones, stimulated in the presence of FTIs, showed a dose-dependent reduction of lineage-specific cytokine secretion (IFN-γ, IL-2, IL-4, IL-5). However, no inhibition of ERK or JNK MAP kinases was observed, nor was induction of cytokine mRNA affected. Rather, intracellular cytokine protein synthesis was blocked. Inhibition of human T-cell INF-γ production also was observed, correlating with reduced phosphorylation of p70S6K. These results indicate that FTIs inhibit T-cell activation at the posttranscriptional level and also suggest that they may have potential as novel immunosuppressive agents.

Abstract: Acute lymphoblastic leukemia (ALL) is a heterogeneous disease and treatment guidelines are still evolving. Allogeneic stem cell transplantation (allo-SCT) offers a potentially curative option and is recommended in first relapse and for high-risk patients in first complete remission (CR). Survival after allo-SCT could be substantially improved due to better risk stratification, patient selection and adapted treatment protocols leading to reduced non-relapse mortality (NRM). Prognostic factors for survival after allo-SCT still need to be defined: pheno- and genotype, patients´ age, conditioning regimens and remission status prior to allo-SCT are under discussion. We analyzed the outcome of 180 consecutive ALL patients who received allo-SCT at the Freiburg University Medical Center between 1995 and 2018 with regard to treatment response, survival, adverse reactions, and performed subgroup analyses to identify prognostic factors. The median age in our cohort was 37 years (ys), 19% were older than 55 ys. 27% were diagnosed with Philadelphia (Ph)-positive ALL, 24% with T-ALL. 36% were treated with relapsed/refractory disease. 48% of allo-SCTs were conducted with a HLA-matched, 19% with a HLA-mismatched unrelated and 33% with a related donor. In 61% the conditioning regimen included total body irradiation (TBI). In 48% no minimal residual disease (MRD) was detected prior to allo-SCT, 20% were transplanted in MRD-positive CR. The overall response rate was 86%, with MRD-negativity in 78%. With a median follow up of 10 ys, we observed a median overall survival (OS) of 23 months and a median progression free survival (PFS) of 11 months. The 10ys-OS was 33%, the 10ys-PFS 31%. The cumulative incidence of relapse was 68% at 10 ys, the cumulative incidence of NRM 12%. Acute graft-versus-host disease (GvHD) III-IV° occurred in 17%, severe chronic GvHD in 9%. Survival was significantly better in patients reaching MRD-negative CR before allo-SCT (10ys-OS 48% vs. 19%, p 〈 0.0001; 10ys-PFS 46% vs. 17%, p 〈 0.001) and in thoses receiving TBI (10ys-OS 40% vs. 19%, p 〈 0.01; 10ys-PFS 37% vs. 19%, p 〈 0.001). There was no significant difference in survival between patients younger or older than 55 ys (10ys-OS 37% vs. 21%, p=0.183; 10ys-PFS 34% vs. 21%, p=0.208) and between those diagnosed with T-, Ph-positive or -negative B-ALL (10ys-OS 41% vs. 35% vs. 29%, p=0.298; 10ys-PFS 38% vs. 33%. vs. 27%, p=0.238). Due to lower NRM, survival improved depending on the year of allo-SCT (10ys-OS 1995-2000 22% vs. 2001-2010 32% vs. 2011-2018 n.r., p 〈 0.01; 10ys-PFS 20% vs. 30% vs. n.r., p 〈 0.01). With a very long follow-up and high rate of MRD-assessment, we observed a high response rate and a low rate of severe GvHD. Our data confirm that allo-SCT enables long-term survival in high-risk ALL, suggest that, in certain subgroups, survival may be best in patients transplanted in CR and receiving TBI for conditioning, including the relevant observation that allo-SCT can be performed in carefully selected elderly patients. Disclosures Finke: Medac: Honoraria, Other: research support, Speakers Bureau; Neovii: Honoraria, Other: research support, Speakers Bureau; Riemser: Honoraria, Other: research support, Speakers Bureau. Wäsch:Pfizer: Consultancy; Sanofi: Other: Travel, Research Funding; Celgene: Other: travel, Research Funding; Jazz: Other: travel, Research Funding; Amgen: Consultancy; Gilead: Consultancy; Sanofi: Consultancy; Novartis: Consultancy; Takeda: Consultancy; Amgen: Other: travel, Research Funding; Gilead: Other: travel, Research Funding.

Abstract: Background: DNA demethylating azanucleoside drugs are known to upregulate HLA molecules and germline/Cancer Testis antigens on malignant cells. Thus these drugs may be considered a rational treatment option also for patients relapsed after allografting. Until now for these patients DLI is standard treatment, with only limited activity of additional low-dose cytarabine (LD-AraC). It has thus been hypothesized that azanucleosides, when given at low doses, may not act solely by cytotoxic effects like LD-AraC, but also via their ability to modulate the aberrant epigenotype of leukemic cells and thus reactivate silenced genes. We have piloted a 3-day schedule of 5-azacytidine (aza) at a total dose (TD) of 300 mg per course (thus substantially lower than the schedule established for treatment of MDS), followed by DLI, in pts with relapse of AML/MDS after allografting. Patients and Methods: Between 10/2006 und 4/2008, 22 patients (20 with AML, 2 with CMML) relapsed after allografting received a 3-day course of aza at 100 mg/day s. c., where feasible followed by DLI 1–2 weeks later. Median age at time of allografting was 62 years (range 28 – 75). 16/22 pts were male, 12 had de novo, 8 secondary (s)AML. 9/22 (41 %) had poor-risk cytogenetics. 20 pts had received Fludarabine-based reduced-toxicity conditioning regimens, 2 conventional myeloablative conditioning. At start of aza, 16, 4 and 1 pt were in 1st, 2nd or 3rd relapse, respectively, 1 pt had refractory sAML. Median number of days from transplant to first aza was 257 (range, 76 to 1492). Median % blasts in bone marrow and peripheral blood before aza was 57 and 5, respectively (ranges, 〈 5– 〉 95, 0–91), one patient had extramedullary relapse. Results: 22 pts received a total of 55 courses of aza (43 courses: 300 mg TD, 10 courses: 375 mg TD, 2 courses: 450 mg TD, 1 course: 540 mg TD), with a median of 2 courses (range, 1–10). In 16/22 pts (73 %), aza was followed by DLI, with a total of 42 courses of aza/DLI given. Treatment was repeated every 4 weeks. Only 1 pt. experienced Grade III aGvHD 2 mths after DLI, clinically relevant neutropenia was observed in 3 pts. 5 patients had disease control and stable mixed chimerism but no objective hematologic response. In 2 pts a stable conversion to complete donor chimerism occurred. 15 pts did not respond to this treatment. 9/22 pts proceeded to second allogeneic transplantation. 7/22 pts are alive at time of analysis. The median time from start of aza to death or last follow-up was 131 days (range 23–625). Conclusions: This low-dose outpatient regimen of aza followed by DLI is feasible, with a very low aGvHD rate. Objective responses including complete donor chimerism (10%) occurred also in pts with poor-risk cytogenetics, and notably also in pts having already received previous DLI monotherapy (suggesting that DLI activity might be enhanced by preceding aza treatment). A dose escalation based on this schedule appears warranted, incorporating translational studies aimed at dissecting whether the effect of aza is via a cytotoxic effect or modulation of gene expression in the malignant cells.

Abstract: The outcome of patients with T cell lymphoma treated with standard chemoterapeutic substances remain poor, making the search for new active substances a highly medical need in this hematologic neoplasia. Recent phase II clinical trials showed very promising activity of farnesyltransferaseinhibitors (FTI) in relapsed/refractory T-NHL patients (Witzig et al. 2011). Regarding the molecular mechanisms behind this therapeutic effect, conflicting data regarding Ras as the initially proposed intracellular target of FTI and the involvement of MAP kinases in cellular effects of FTI in T cells exist (Marks et al. 2007, Ding et al. 2011). Together with observations in breast and ovarian cancer cells suggesting the GTPase Rheb as target for inhibition of farnesylation (Basso et al. 2005), the targets of FTI might vary according to the examined cell type. Interestingly, in breast cancer cells FTI mediatied inhibition of Rheb action resulted in reduced mTOR signaling. Nevertheless, as a putative additional targeted treatment approach in T-NHL, incubation with mTOR inhibitors showed not only substantial antiproliferative effects in normal T cells but also in malignant human T cell lymphoma lines in vitro (Huang et al. 2010). Since further clinical trials with both substances did not show severe side effects, adding everolimus as combination partner might even enhance clinical activity of FTI in T cell lymphomas. Therefore, in order to test this hypothesis and to analyse if both substances differ in their molecular mechanisms of action, FTI and everolimus were tested in vitro in T cell lymphoma lines (Karpas, Derl-2, Jurkat) to evaluate potential synergistic modes of action. Methods and Results Incubation of human T cell lymphoma lines Karpas and Derl-2 with the FTI SCH66336 (lonafarnib) or the mTOR inhibitor everolimus showed a reduction in proliferation in a dose dependent manner (EC50 for everolimus: 0.1nM, EC50 for lonafarnib: 0.5 µM). Combining both drugs resulted in synergistic inhibition of proliferation. This inhibitory effect correlated with increased p27KIP1 expression. In our experiments, Rheb appeared to be highly expressed in all examined T cell lymphoma lines with even additional increase of protein expression in Karpas cells after FTI incubation. Comparing FTI action to inhibition of mTOR by everolimus on a molecular level, in our experiments lonafarnib treatment of Karpas cells resulted in an unexpected reduction in AMPK-phosphorylation, implicating involvement of this metabolic pathway in FTI mediated inhibition of proliferation in malignant T cells. This effect could not be observed in everolimus treated Karpas cells. In contrast, naive human CD4+ T cells showed very little Rheb protein expression, which could be significantly increased after TCR stimulation by induction of Rheb mRNA transcription. While everolimus treatment of TCR-activated normal human CD4+ T cells resulted in AKT-hyperphosphorylation, FTI did not induce any changes in AKT. Contrary to the malignant T cells, FTI treatment had no impact of AMPK phosphorylation in activated T cells. Actually, naive T cells treated with FTI showed an hyperphosphorylated AMPK status. Conclusion Lonafarnib and everolimus show synergistic antiproliferative effects in T cell lymphoma lines, most likely by interfering with mTOR and AMPK signalling, making this combination therapy interesting for clinical trials. In contrast, FTI does not mediate AMPK in activated normal T cells. This observations are in accordance with a differential targeting of Rheb by FTI in malignant or normal human T cells. Disclosures: No relevant conflicts of interest to declare.

Abstract: Background: Allogeneic hematopoietic cell transplantation is a potentially curative therapy for patients with hematological malignancies. However a fraction of patients will develop corticosteroid-refractory (SR) acute (a) and chronic (c) graft-versus-host disease (GVHD) which both cause a high mortality and impaired quality of life. Pre-clinical evidence indicates the potent anti-inflammatory properties of the JAK1/2 inhibitor ruxolitinib by modification of T cells and dendritic cells. Methods: In this retrospective analysis, 19 stem cell transplant centers in Europe and the United States reported clinical outcome data from 95 patients who had received ruxolitinib as salvage-therapy for SR-GVHD. Patients were classified as having SR-aGVHD (n=54, all grade III or IV) or SR-cGvHD (n=41, all moderate or severe). The median number of previous GVHD-therapies was 3 for both SR-aGVHD (1-7) and SR-cGvHD (1-10). The median follow-up times were 26.5 (3-106) for SR-aGVHD and 22.4 (3-135) weeks for SR-cGVHD-patients. Results: The ORR was 81.5% (44/54) in SR-aGVHD including 25 CRs (46.3%), while for SR-cGVHD the ORR was 85.4% (35/41). The median time to response was 1.5 (1-11) and 3 (1-25) weeks after initiation of ruxolitinib treatment in SR-aGVHD and SR-cGVHD, respectively. Of those patients responding to ruxolitinib, the rate of GVHD-relapse was 6.8% (3/44) and 5.7% (2/35) for SR-aGVHD and SR-cGVHD, respectively. The 6-month-survival was 79% (67.3%-90.7%,95% CI) and 97.4% (92.3%-100%,95% CI) for SR-aGVHD and SR-cGVHD, respectively. Cytopenia and CMV reactivation were observed during ruxolitinib-treatment in both SR-aGVHD (30/54, 55.6% and 18/54, 33.3%) and SR-cGVHD (7/41, 17.1% and 6/41, 14.6%) patients. Relapse of the underlying malignancy occurred in 9.3% (5/54) and 2.4% (1/41) of the patients with SR-aGVHD or SR-cGVHD, respectively. Conclusion: Ruxolitinib constitutes a promising new treatment option for SR-aGVHD and SR-cGVHD. Its activity in SR-aGVHD and SR-cGVHD should be validated in a prospective trials in both, SR-aGvHD and cGvHD. Disclosures Bertz: GILEAD Sciences: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding. Scheid:Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees; Janssen-Cilag: Honoraria, Membership on an entity's Board of Directors or advisory committees. Bug:TEVA Oncology, Astellas: Other: Travel Grant; NordMedica, Boehringer Ingelheim, Gilead: Membership on an entity's Board of Directors or advisory committees; Celgene, Novartis: Research Funding.