Kurzfassung: Graft versus Host Disease (GVHD) and treatment related mortality (TRM) are the major limitations to the widespread application of allogeneic haematopoietic stem cell transplantation (HSCT) for haematological and non-haematological malignancies. Dendritic cells (DC) as the key initiators and directors of the immune response are central to allogeneic transplant interactions. Preparative conventional conditioning (CC) regimens aim to control disease and ablate the host immune response to facilitate normal haematopoietic reconstitution. The conditioning also unleashes a cytokine storm that activates the residual host immune system, driving host DC and donor T cell interactions that result in GVHD. Reducing the intensity of conditioning (RIC) regimens maintains immune anti-leukaemic activity of T replete HSCT, reduces TRM and delays the onset of GVHD, but the overall incidence of GVHD is unchanged. We hypothesise that this is due to increased persistence of host DC. We propose that strategic administration of DC depleting antibodies could be an effective means to control GVHD. Whilst there is some information on the effects of CC on DC; we have shown that mature plasmacytoid (p) DC are increased in mouse spleen after conditioning by radiation, there is no information on the effects of RIC on DC. We have established murine models of conditioning (CC = Cyclophosphamide [CY] + 800cGy and RIC = Fludarabine [FLU] + CY + 200cGy). The effects on DC numbers, activation and subset composition (myeloid (m) DC and DC), cytokine and systemic endotoxin levels were studied on each day of the conditioning regimens in the absence of HSCT. Mice receiving CC have a significantly higher percentage of DC which are pDC compared to RIC (p & lt;0.001) which results in a decrease in the overall percentage of mDC. However, mice that received RIC have significantly higher absolute numbers of host pDC than CC mice. Preliminary data shows no difference in endotoxin levels in mice receiving RIC or CC without HSCT. However, there may be a transient increase in endotoxin levels in mice after 2 FLU injections (p=0.12). No such increase was seen after CC. There were significantly higher levels of TNF-α (p=0.02) and IL1-β (p=0.03) in mice receiving RIC rather than CC without HSCT. The higher absolute numbers of DC, altered subset ratio and cytokine production appears to account for the delayed onset of GVHD in RIC transplant recipients. Intra-peritoneal (ip) injection of N418, a monoclonal antibody to mouse leukocyte integrin CD11c depleted murine DC in vivo. Preliminary experiments show elimination of 50% of DC after injection of N418 (500mg). Subsequent experiments show that 1mg of N418 is sufficient to significantly delay, but not prevent, GVHD in a full MHC mismatched model of HSCT (p=0.025). The action of N418 is specific, as DC depletion was not seen in mice treated with 1 mg hamster Ig. Together, these observations suggest that increasing antibody concentration and prolonged administration may be required to prevent GVHD. The successful application of DC depletion to control GVHD will improve the safety of HSCT for patients with leukaemia.

Kurzfassung: Introduction Patients (pts) with MF who discontinue ruxolitinib due to resistance or progression have a poor prognosis (median OS, 14 months; Kuykendall et al. Ann Hematol. 2018). Available therapies provide symptom control and reduce spleen volumes, but do not address the underlying pathophysiology of disease, underscoring a need for disease-modifying treatments. Murine double minute 2 (MDM2), a key negative regulator of the tumor suppressor protein p53, is overexpressed in CD34+ cells in MF. Elevated MDM2 attenuates p53 activity resulting in proliferation of malignant CD34+ cells. Navtemadlin (KRT-232), a potent, selective, orally available MDM2 inhibitor, restores p53 function and mediates apoptosis of malignant cells, suggesting a potential for disease-modification. As previously reported in relapsed/refractory (R/R) MF, once-daily navtemadlin at 240 mg (Day 1-7/28-day cycle) yielded a best spleen volume reduction (SVR) ≥35% by central review in 16% of pts, best total symptom score (TSS) response & gt;50% in 30% of pts, and an 87% reduction of peripheral CD34+ cells at Week 24 (Al-Ali et al. EHA 2020). Aims To evaluate the correlations between changes in biomarkers of disease burden (variant allele frequency [VAF] of driver mutation and high-molecular risk (HMR) genes, peripheral blood CD34+ cells, serum cytokine levels, and bone marrow fibrosis) and clinical benefits (spleen volume reduction and symptom response). Methods Pts with R/R MF were treated in a phase 2 trial with different doses/schedules of navtemadlin (NCT03662126). Peripheral blood samples were collected at baseline and after 12 and 24 weeks of navtemadlin. Analysis of driver and HMR mutations (ASXL1, EZH2, SRSF2, IDH1/2, U2AF1) and VAF measurements from peripheral blood were determined by next-generation sequencing. Serum TNFα was analyzed by ELISA. Bone marrow biopsies were collected at baseline and after 24 weeks of treatment; fibrosis was assessed by a central pathology review. Correlations were investigated by calculating Spearman's rank-correlation coefficients. Results As of April 15, 2021, of 113 pts treated with navtemadlin, 111 were evaluable for mutation analyses. At baseline, 108 pts had ≥1 driver mutation and 75 pts had ≥1 mutation in an HMR gene Driver mutations in JAK2, CALR, or MPL were reported in 81 (73%), 22 (19%) and 13 (12%) of pts, respectively; 28 (25%) carried mutations in ≥2 HMR genes. Of 65 pts evaluable for driver gene or HMR VAF reductions, a best driver gene reduction ≥20% after navtemadlin was observed in 22 (34%) pts and 19 (29%) showed a complete VAF reduction (below the limit of detection) in HMR or driver genes (Fig 1). Reduction in driver allele VAF at any time on study significantly correlated with SVR (Fig 2A); SVR responses were noted in more pts with ≥20% vs & lt;20% decrease in driver VAFs (32% vs 5%; P=0.0072). Reductions in circulating CD34+ cells in peripheral blood observed with navtemadlin treatment correlated significantly with best SVR (Fig 2B). Navtemadlin induced reductions in serum TNFα with a median best decrease from baseline of 41%. Reductions in TNFα correlated with best SVR and TSS responses (Fig 2C and 2D). Of 45 pts who had bone marrow biopsies at baseline and Week 24, 41 (91%) had baseline fibrosis scores ≥1, with 31 (69%) and 4 (9%) having Grade 2 and 3 fibrosis, respectively. After navtemadlin treatment, 12 (27%) showed improved fibrosis scores of ≥1 grade and 23 (51%) had stable fibrosis scores. Among responders, fibrosis scores were improved or stable in 67% of pts with SVR ≥35% and 100% of pts with TSS improvement ≥50%. Fibrosis scores were also associated with improvements in mutation burden; of 14 patients with VAF reductions ≥20% and bone marrow assessments, 4 (29%) showed improvements in fibrosis and 8 (57%) had stable fibrosis scores. Conclusion Among pts with R/R MF treated with navtemadlin, spleen responses correlated with reductions of MPN-driver mutation burden, decreased peripheral CD34+ cell counts, improvements in bone marrow fibrosis scores, and reduction in inflammatory cytokine, TNFα. Improvement in symptom burden significantly correlated with reductions in TNFα. The reduction in mutation burden and CD34+ cells, together with an improvement in bone marrow fibrosis, suggest that navtemadlin has a disease-modifying effect in MF. These correlations will be explored further in BOREAS, a global phase 3 study in MF that is R/R to JAK inhibitors (NCT03662126). Figure 1 Figure 1. Disclosures Vachani: Pfizer: Consultancy, Membership on an entity's Board of Directors or advisory committees; Incyte: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; AbbVie: Consultancy, Membership on an entity's Board of Directors or advisory committees; Blueprint Medicines: Consultancy, Membership on an entity's Board of Directors or advisory committees; Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees. Delgado: Novartis: Consultancy, Research Funding, Speakers Bureau; Janssen: Consultancy, Research Funding, Speakers Bureau; Abbvie: Consultancy. Al-Ali: Incyte: Research Funding; Bristol Myers Squibb: Consultancy, Honoraria, Research Funding; Novartis: Consultancy, Honoraria, Research Funding; Takeda: Consultancy; Pfizer: Consultancy; AbbVie: Consultancy, Honoraria. Hernández-Rivas: Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Celgene/BMS: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Pfizer: Honoraria, Membership on an entity's Board of Directors or advisory committees; Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees. Kiladjian: Incyte Corporation: Membership on an entity's Board of Directors or advisory committees; Novartis: Membership on an entity's Board of Directors or advisory committees; Taiho Oncology, Inc.: Research Funding; Bristol Myers Squibb: Membership on an entity's Board of Directors or advisory committees; PharmaEssentia: Other: Personal fees; AOP Orphan: Membership on an entity's Board of Directors or advisory committees; AbbVie: Membership on an entity's Board of Directors or advisory committees. Vannucchi: BMS: Honoraria, Membership on an entity's Board of Directors or advisory committees; Incyte: Honoraria, Membership on an entity's Board of Directors or advisory committees; Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees; AbbVie: Membership on an entity's Board of Directors or advisory committees. Perkins: Novartis: Consultancy, Honoraria, Speakers Bureau; Celgene: Consultancy; Abbvie: Honoraria, Speakers Bureau. Valmeekam: Telios Pharmaceuticals: Current Employment, Current holder of stock options in a privately-held company, Other: travel, accommodations, expenses. Krejsa: Seattle Genetics: Current equity holder in publicly-traded company, Divested equity in a private or publicly-traded company in the past 24 months; Kartos Therapeutics: Current Employment, Current holder of stock options in a privately-held company, Other: travel, accommodations, expenses; AstraZeneca: Current equity holder in publicly-traded company; Acerta Pharma: Current holder of individual stocks in a privately-held company. Uyei: Kartos Therapeutics: Current Employment, Current holder of individual stocks in a privately-held company; Genentech/Roche: Ended employment in the past 24 months; Gilead Sciences: Current equity holder in publicly-traded company; Telios Pharma: Current holder of individual stocks in a privately-held company. McGreivy: Kartos Therapeutics: Current Employment, Current holder of stock options in a privately-held company. Rothbaum: Quogue Capital: Current Employment; Iovance Biotherapeutics: Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees, Other: travel, accommodations, expenses; Acerta Pharma/Astra Zeneca: Current equity holder in publicly-traded company; Kartos Therapeutics: Current holder of individual stocks in a privately-held company, Membership on an entity's Board of Directors or advisory committees, Other: travel, accommodations, expenses, Patents & Royalties; Telios Pharma: Current holder of individual stocks in a privately-held company, Membership on an entity's Board of Directors or advisory committees, Other: travel, accommodations, expenses, Patents & Royalties; Quogue IP Holdings: Patents & Royalties. Mascarenhas: PharmaEssentia: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Kartos: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Forbius: Research Funding; Roche: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Incyte: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Merck: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Genentech/Roche: Consultancy, Membership on an entity's Board of Directors or advisory committees; Gilead: Consultancy, Membership on an entity's Board of Directors or advisory committees; Promedior: Consultancy, Membership on an entity's Board of Directors or advisory committees; CTI Biopharm: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; AbbVie: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Geron: Consultancy, Research Funding; Constellation: Consultancy, Membership on an entity's Board of Directors or advisory committees; Celgene/BMS: Consultancy, Membership on an entity's Board of Directors or advisory committees; Sierra Oncology: Consultancy, Membership on an entity's Board of Directors or advisory committees; Merus: Research Funding; Geron: Consultancy; Galecto: Consultancy; Prelude: Consultancy. Verstovsek: CTI BioPharma: Research Funding; Blueprint Medicines Corp: Research Funding; Roche: Research Funding; Ital Pharma: Research Funding; Promedior: Research Funding; PharmaEssentia: Research Funding; Protagonist Therapeutics: Research Funding; NS Pharma: Research Funding; Celgene: Consultancy, Research Funding; Genentech: Research Funding; Gilead: Research Funding; Incyte Corporation: Consultancy, Research Funding; Sierra Oncology: Consultancy, Research Funding; AstraZeneca: Research Funding; Novartis: Consultancy, Research Funding; Constellation: Consultancy; Pragmatist: Consultancy. OffLabel Disclosure: Navtemadlin (KRT-232) is an investigational agent that is being evaluated in a clinical trial setting.

Kurzfassung: Chronic obstructive pulmonary disease (COPD) is associated with age and smoking, but other determinants of the disease are incompletely understood. Clonal hematopoiesis of indeterminate potential (CHIP) is a common, age-related state in which somatic mutations in clonal blood populations induce aberrant inflammatory responses. Patients with CHIP have an elevated risk for cardiovascular disease, but the association of CHIP with COPD remains unclear. We analyzed whole-genome sequencing and whole-exome sequencing data to detect CHIP in 48 835 patients, of whom 8444 had moderate to very severe COPD, from four separate cohorts with COPD phenotyping and smoking history. We measured emphysema in murine models in which Tet2 was deleted in hematopoietic cells. In the COPDGene cohort, individuals with CHIP had risks of moderate-to-severe, severe, or very severe COPD that were 1.6 (adjusted 95% confidence interval [CI], 1.1-2.2) and 2.2 (adjusted 95% CI, 1.5-3.2) times greater than those for noncarriers. These findings were consistently observed in three additional cohorts and meta-analyses of all patients. CHIP was also associated with decreased FEV1% predicted in the COPDGene cohort (mean between-group differences, −5.7%; adjusted 95% CI, −8.8% to −2.6%), a finding replicated in additional cohorts. Smoke exposure was associated with a small but significant increased risk of having CHIP (odds ratio, 1.03 per 10 pack-years; 95% CI, 1.01-1.05 per 10 pack-years) in the meta-analysis of all patients. Inactivation of Tet2 in mouse hematopoietic cells exacerbated the development of emphysema and inflammation in models of cigarette smoke exposure. Somatic mutations in blood cells are associated with the development and severity of COPD, independent of age and cumulative smoke exposure.

Kurzfassung: Low-dose IL-2 is efficacious in steroid-refractory cGVHD, with objective responses in 〉 50% of patients, and durable disease control. IL-2 initiation earlier after cGVHD onset, prior to severe impairment of Treg:Tcon ratios, improves likelihood of clinical response.

Kurzfassung: Toxicities of high-dose conditioning regimens have limited the use of conventional unrelated donor hematopoietic cell transplantation (HCT) to younger, medically fit patients. Based on preclinical studies, an HCT approach has been developed for elderly or medically infirm patients with HLA-matched or mismatched unrelated donors. In this study, 52 patients with hematological diseases were included. Most (88%) had preceding unsuccessful conventional HCT or refractory/advanced disease. Patients were treated with fludarabine 30 mg/m2/d from days −4 to −2, 2 Gy total body irradiation on day 0, cyclosporine at 6.25 mg/kg twice daily from day −3, and mycophenolate mofetil at 15 mg/kg twice daily from day 0. Durable donor chimerism was attained in 88% of the patients. By day 28, a median of 100% of CD56+ cells were of donor origin. Granulocyte and T-cell donor chimerism increased to medians of 100% on day 56 and day 180 (range, 55%-100%), respectively. Acute GVHD, grade II, was seen in 42% (CI, 29%-56%); grade III in 8% (CI, 0%-15%); and grade IV in 13% (CI, 4%-23%) of patients; it was fatal in 9%. The 100-day transplantation-related mortality was 11%. Complete remissions, including molecular remissions, were seen in 45% of patients with measurable disease before transplantation. Mortality from disease progression was 27% at one year. With a median follow-up of 19 months, 18 of the 52 patients (35%) were alive and 25% were in remission. HCT from HLA-matched or mismatched unrelated donors can be performed with a reduced intensity conditioning regimen in patients ineligible for conventional HCT.