Kurzfassung: Background: Distinct from broadly acting graft-versus-host disease (GVHD) prophylaxis, JAK2 inhibition suppresses alloreactive T cells, while sparing regulatory T cells (Tregs) and graft-versus-leukemia (GVL). Early IL-6 activity via JAK2 and phosphorylated STAT3 in CD4+ T cells is associated with acute GVHD onset. In mice, we show combined JAK2/mTOR blockade synergistically prevents xenogeneic GVHD. In this first-in-human phase I/II GVHD prevention trial we combine pacritinib, a JAK2 inhibitor, with sirolimus to concurrently reduce T-cell costimulation via mTOR and IL-6 activity. With phase I complete, we demonstrate that dual JAK2/mTOR inhibition is safe, suppresses pathogenic Th1 and Th17 cells, spares Tregs and key GVL effector cells, and exhibits preliminary activity in preventing GVHD. The primary aim of phase I was to identify the lowest biologically active dose of pacritinib (defined as & lt; 35% of CD4+ pSTAT3+ T cells at day +21) that is safe when combined with sirolimus-based immune suppression. The preliminary activity of JAK2/mTOR inhibition in GVHD prevention was also investigated. Materials and Methods: This single-arm phase I/II trial (NCT02891603) tested the safety of pacritinib when administered with sirolimus plus low-dose tacrolimus (PAC/SIR/TAC) after allogeneic hematopoietic cell transplantation (alloHCT). A 3+3 dose escalation design was followed, including dose level 1 (PAC 100mg daily), level 2 (PAC 100mg twice daily), and level 3 (PAC 200mg twice daily). Clinical safety, pharmacodynamic assessments, and pharmacokinetic (PK) studies were followed during the study. Acute GVHD was scored through day +100. Patient characteristics are described in Table 1 (n=12). Allowed donor types were HLA-A, -B, -C, and -DRB1 matched-related or unrelated donors. Adequate vital organ function and Karnofsky performance status (KPS ≥ 80%) were required. Results: Dose level 2, PAC 100mg twice a day, was the lowest biologically active and safe dose, and thus the recommended phase II dose. Blood samples acquired at day +21 showed that PAC 100mg twice a day reduced the mean frequency and geometric MFI of CD4+ pSTAT3+ T cells (Figure 1A, B). Consistent with suppressed pSTAT3, PAC 100mg twice a day decreased pathogenic Th1 and Th17 cells (Figure 1C, D). pSTAT5 is critical for Tregs and effectors of GVL. PAC 100mg twice a day favored STAT5 phosphorylation in CD4+ T cells, preserved Tregs and increased the ratio of Tregs to pathogenic T helper cells, and supported CD3+ T cell and NK cell effectors (Figure 1E-J). Patients treated on dose level 2 of PAC exhibited a robust increase in Th2 cells at day +21 (29.5% v 4.87% level 1 or 4.5% baseline, P & lt;0.001 ANOVA). Additionally, neutrophil and platelet engraftment occurred without delay (Figure 1K, L). A single dose limiting toxicity was observed in dose level I only, and consisted of angioedema possibly related to PAC. CMV reactivation or disease were not observed among patients treated at dose level 2, with only a single case of CMV reactivation among dose level 1 (8 of 12 recipients were CMV seropositive). A single patient treated on dose level 2 developed grade 4 acute GVHD and died, after prematurely discontinuing TAC for acute kidney injury and electively stopping PAC. A patient died of relapsed disease in dose level 1. To test the efficacy of dual JAK2/mTOR inhibition in vivo, NSG mice were transplanted with human peripheral blood mononuclear cells (PBMCs) and treated with either vehicle, PAC, STAT3 inhibitor S3I-201, SIR, PAC/SIR, or S3I/SIR. The combination of JAK2 or downstream STAT3 inhibition plus SIR significantly reduced xenogeneic GVHD in mice (Figure 1M) and maintained donor anti-tumor activity by CD8+ T cells (data not shown). Further, dual JAK2 or STAT3 inhibition with mTOR blockade significantly increased the induction of Tregs in mice transplanted with Treg-depleted human PBMCs (62.3% PAC/SIR or 74% S3I/SIR v 29.9-38% with vehicle or inhibitors alone, P & lt;0.01 ANOVA). Conclusions: We demonstrate that PAC/SIR/TAC (RP2D: PAC 100mg twice a day) is safe and effectively reduces IL-6 signal transduction, pathogenic Th1 and Th17 cells, and preserves Tregs and effectors necessary for GVL and antiviral immunity. Preliminarily, adding pacritinib limits acute GVHD, preserves donor CMV immunity, and permits timely engraftment. The efficacy of PAC/SIR/TAC will be tested in our ongoing phase II GVHD prevention trial. Disclosures Pidala: Syndax: Consultancy, Membership on an entity's Board of Directors or advisory committees; CTI Biopharma: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Amgen: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis: Research Funding; Takeda: Research Funding; Janssen: Research Funding; Johnson and Johnson: Research Funding; Pharmacyclics: Research Funding; Abbvie: Research Funding; BMS: Research Funding. Bejanyan:Kiadis Pharma: Membership on an entity's Board of Directors or advisory committees. Nishihori:Karyopharm: Other: Research support to institution; Novartis: Other: Research support to institution. Lawrence:Patent Pending: Patents & Royalties: Dr. Lawrence has a patent WO2014070859A1: Stat3 dimerization inhibitors. . Lawrence:Patent Pending: Patents & Royalties: Dr. Lawrence has a patent WO2014070859A1: Stat3 dimerization inhibitors. . Sebti:Patent Pending: Patents & Royalties: Dr. Sebti has a patent WO2014070859A1: Stat3 dimerization inhibitors. . Betts:Patent Pending: Patents & Royalties: Dr. Betts has a pending patent WO2017058950A1: Methods of treating transplant rejection. This includes the use of JAK inhibitors. Neither he nor his institution have received payment related to claims described in the patent.. OffLabel Disclosure: Pacritinib and its use in GVHD prevention as part of a phase I trial

Kurzfassung: Peripheral blood stem cell (PBSC) as a graft source compared to bone marrow has been reported to result in lower risk of relapse after haploidentical hematopoietic cell transplantation (haplo-HCT) with use of post-transplant cyclophosphamide (PTCy) as a graft-versus-host-disease (GvHD) prophylaxis. However, cytokine release syndrome (CRS) is a common complication of this platform that can affect the outcomes of patients after PBSC haplo-HCT. CRS occurs due to rapid activation and proliferation of alloreactive donor T cells resulting in the elevated secretion of inflammatory cytokines. In this study, we sought to examine the risk factors for CRS and the effect of CRS severity on outcomes of PBSC haplo-HCT. We identified total of 271 consecutive patients with hematological malignancies who received their first PBSC haplo-HCT with PTCy-based GVHD prophylaxis at City of Hope (n=157) or Moffitt (n=114) Cancer Centers between 2014 and 2019. The median patient age at HCT was 54 years (INQ range, 37-64) for the entire cohort and 48% of the patients had HCT-CI ³3. Close to 70% of the study cohort had acute leukemia and 33% of all patients had high/very high-risk disease risk index. Myeloablative conditioning was used in 52% of the cases and 81% of all HCT recipients were CMV seropositive. The median donor age at HCT was 33 years (INQ range, 26-43). The HLA -A, -B, -C, -DRB1, -DQB1, or -DPB1 mismatch between the recipient and the donor in the GVH direction was 5/10 in 51%, 4/10 in 29% and £3/10 in 20% of cases. Offspring donors were used in 54% of the patients, sibling donors in 35%, and parent/other relative donors in 11%. Female donors to male recipients were used in only 22% of patients. The median infused CD34 dose was 5.25 x106 cells/kg (range, 2.3-22.4x106) and the CD3 dose was 2.48x108 cells/kg (range, 0.002-8.88 x108). CRS of any grade by ASTCT criteria was observed in 92% of study patients within first 7 days of HCT: 54% had grade 1, 39% grade 2, and 5.2% grade 3-4. Infused cell doses of CD34 & gt;5x106 cells/kg and of CD3 & gt;2.5x108 cells/kg had no significant effect on grade 3-4 CRS. On multivariable analysis, the use of reduced-intensity conditioning (RIC) was associated with increased grade 2-4 CRS (HR = 1.6, 95% CI: 1.11.-2.33, p=0.01) and grade 3-4 CRS (HR = 14.7, 95% CI: 1.97-109.5, p=0.009) compared with the myeloablative conditioning. Donor 5/10 HLA-mismatch was also associated with increased grade 2-4 CRS (HR = 1.5, 95% CI: 1.05-2.18; p=0.03) and grade 3-4 CRS (HR = 3.50, 95% CI: 1.00-12.32; p=0.05) compared with £4/10 HLA-mismatch. Non-relapse mortality (NRM) at day 100, and 1-year overall survival (OS) by CRS severity is shown in Figure. Comparing with the grade 0-1 CRS in multivariable analysis (Table), increase in CRS severity was associated with lower probability of neutrophil engraftment (HR = 0.9 for grade 2 and HR = 0.4 for grade 3-4; p=0.03). Increased CRS severity as compared to the grade 0-1 was also predictive of higher risks of NRM (HR = 1.6, 95% CI: 0.95-2.79 for grade 2 and HR = 6.6, 95% CI: 3.12-13.78 for grade 3-4; p & lt;0.001), lower disease-free survival (DFS; HR = 1.3 for grade 2 and HR = 4.5 for grade 3-4; p & lt;0.001) and lower OS (HR = 1.2 for grade 2 and HR = 4.1 for grade 3-4; p & lt;0.001) after HCT. We observed no association between CRS severity and risk of relapse or the incidence and severity of acute GvHD after transplant. We conclude that CRS is a common complication after PB haplo-HCT/PTCy. CRS severity is associated with post-HCT outcomes with grade 3-4 CRS associated with the highest risk of NRM and overall mortality after HCT. Infused CD34 or CD3 cell doses effect on CRS is unclear. RIC and higher degree of HLA-mismatch are predictive of higher-grade CRS. Identification of modifiable risk factors can help to mitigate the risk for serious CRS and subsequent mortality after PB haplo-HCT/PTCy. Figure 1 Disclosures Nishihori: Karyopharm: Other: Research support to institution; Novartis: Other: Research support to institution. Pidala:CTI Biopharma: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Amgen: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis: Research Funding; Takeda: Research Funding; Janssen: Research Funding; Johnson and Johnson: Research Funding; Pharmacyclics: Research Funding; Abbvie: Research Funding; BMS: Research Funding; Syndax: Consultancy, Membership on an entity's Board of Directors or advisory committees. Nakamura:Merck: Other: advisory board meeting; Alexion: Other: Support on a meeting presentation; Kyowa-Kirin: Other: Support on a meeting presentation; Celgene: Other: Support on seminar; Magenta Therapeutics: Other: Advisory board meeting; Viracor: Consultancy; Kadmon Corporation: Other: Advisory board meeting; NapaJen Pharma: Consultancy. Al Malki:Rigel Pharma: Consultancy; Jazz Pharmacuticals, Inc: Consultancy; Neximmune: Consultancy. Bejanyan:Kiadis Pharma: Membership on an entity's Board of Directors or advisory committees.

Kurzfassung: The NCCN Guidelines for Hematopoietic Cell Transplantation (HCT) provide an evidence- and consensus-based approach for the use of autologous and allogeneic HCT in the management of malignant diseases in adult patients. HCT is a potentially curative treatment option for patients with certain types of malignancies; however, recurrent malignancy and transplant-related complications often limit the long-term survival of HCT recipients. The purpose of these guidelines is to provide guidance regarding aspects of HCT, including pretransplant recipient evaluation, hematopoietic cell mobilization, and treatment of graft-versus-host disease—a major complication of allogeneic HCT—to enable the patient and clinician to assess management options in the context of an individual patient’s condition. These NCCN Guidelines Insights provide a summary of the important recent updates to the NCCN Guidelines for HCT, including the incorporation of a newly developed section on the Principles of Conditioning for HCT.

Kurzfassung: Background: Primary and secondary [post-essential thrombocythemia (ET) or polycythemia vera (PV)] Myelofibrosis (MF) are clonal hematopoietic neoplasms marked by constitutive JAK-STAT activation, bone marrow fibrosis, cytopenias, and constitutional symptom burden. Allogeneic hematopoietic cell transplantation (HCT) is the only curative option in this disease. Median overall survival (OS) after JAK inhibitor (JAKi) discontinuation is poor, ranging from 6-24 months (Harrision et al. Ann Hematol. 2020). Haploidentical (Haplo)-HCT with post-transplant cyclophosphamide (PTCy) has improved donor availability, but data on post-HCT outcomes in MF remain scarce. Herein, we describe clinical outcomes of patients (pts) with MF who underwent haplo-HCT with PTCy. Methods: We conducted a multi-institutional study where we retrospectively reviewed charts to obtain pt, disease, and treatment characteristics of MF pts who underwent haplo-HCT from 2000 to 2019. Graft-versus-host-disease (GVHD), relapse, and non-relapse mortality (NRM) were described as cumulative incidences. OS and relapse free survival (RFS) were estimated using the Kaplan-Meier method. Univariate analyses were conducted with Cox or Fine and Gray regression. Results: Fifty-eight adult pts from 11 centers underwent haplo-HCT and were included in the analysis. Pt, disease, and HCT characteristics are listed in Table 1. Thirty-four (59%) pts were over 60 years of age at the time of HCT. Of the 53 pts in whom driver mutation data was available, JAK2 was reported in 34 (64%), CALR in 10 (19%), MPL in 4 (8%), and 5 (9%) were triple-negative. Twenty-two (38%) pts had HCT-CI ≥ 3. Median CD34+ cell dose was 6.81 (range: 2.3-28.6) x 106/kg. All pts received PTCy as a part of GVHD prophylaxis regimen. Median follow-up in this study was 28 (range: 3.3-75.7) months. Neutrophil and platelet engraftment was reported in 53 (91%) and 47 (81%) pts at a median time of 20 (range: 14-70) and 31 (range: 15-225) days, respectively. Five pts (9%) had graft failure. The cumulative incidences of all-grade acute and chronic GVHD were in 44% (95% CI: 31-56%) at 6 months and 31% (95% CI: 18-44%) at 2 years. Grade 3-4 acute GVHD was seen in 5 (9%) pts. Post-HCT relapse/disease persistence occurred in 12 (21%) pts with a median of 416 (range: 28-917) days. The 2-year estimates of OS, RFS, relapse and NRM were 69% (95% CI: 55-80%), 52% (95% CI: 37-65%), 21% (95% CI: 11-34%) and 27% (95% CI: 16-39%) respectively (Fig 1). On univariate analyses (Table 2), older age (HR 2.17, P=.012) and a higher HCT-CI (HR 1.4, P & lt;.001) was associated with higher NRM. Higher HCT-CI was also associated with higher all-cause mortality (HR 1.38, P=.003). Bone marrow as a graft source was associated with a higher risk of relapse (HR 5.04, P & lt;0.001, Fig 2), but did not significantly affect OS (HR 0.78, 95% CI: 0.18-3.46), RFS (HR 1.89, 95% CI: 0.71-5.02) or NRM (HR 0.58, 95% CI: 0.09-3.84). JAKi use prior to HCT, spleen size or type of driver mutation did not significantly affect outcomes. Conclusions: Based on this study, we conclude that haplo-HCT with PTCy is a valid option in pts with MF. The graft failure rates appear to be similar to those reported with sibling and unrelated donors. Older age, higher HCT-CI and bone marrow as graft source were associated with inferior outcomes. JAKi use prior to HCT or type of driver mutation did not significantly affect outcomes. Disclosures Grunwald: Trovagene: Consultancy; Daiichi Sankyo: Consultancy; Merck: Consultancy; Agios: Consultancy; Janssen: Research Funding; Cardinal Health: Consultancy; Incyte: Consultancy, Research Funding; Daiichi Sankyo: Consultancy; Forma Therapeutics: Research Funding; Amgen: Consultancy; Celgene: Consultancy; Incyte: Consultancy, Research Funding; Celgene: Consultancy; Celgene: Consultancy; Pfizer: Consultancy; Incyte: Consultancy, Research Funding; Merck: Research Funding; Astellas: Consultancy; Genentech/Roche: Research Funding; Premier: Consultancy; Premier: Consultancy; Astellas: Consultancy; Premier: Consultancy; Daiichi Sankyo: Consultancy; Agios: Consultancy; Abbvie: Consultancy; Merck: Consultancy; Pfizer: Consultancy; Trovagene: Consultancy; Trovagene: Consultancy; Abbvie: Consultancy; Abbvie: Consultancy; Agios: Consultancy; Forma Therapeutics: Research Funding; Forma Therapeutics: Research Funding; Astellas: Consultancy; Amgen: Consultancy; Amgen: Consultancy; Merck: Consultancy; Cardinal Health: Consultancy; Pfizer: Consultancy; Cardinal Health: Consultancy; Janssen: Research Funding; Genentech/Roche: Research Funding; Genentech/Roche: Research Funding. Dholaria:J & J: Research Funding; Takeda: Research Funding; Angiocrine: Research Funding; bms: Research Funding; Poseida: Research Funding. Abedin:Jazz Pharmaceuticals: Honoraria; Agios: Honoraria; Helsinn Healthcare: Honoraria; Pfizer: Research Funding; Helsinn Healthcare: Research Funding; Actinium Pharmaceuticals: Research Funding. Gupta:Novartis: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Pfizer: Consultancy; Incyte: Honoraria, Research Funding; Bristol MyersSquibb: Honoraria, 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. DeZern:MEI: Consultancy; Celgene: Consultancy, Honoraria; Astex: Research Funding; Abbvie: Consultancy. Gerds:Sierra Oncology: Research Funding; Pfizer: Research Funding; Celgene: Consultancy, Research Funding; CTI Biopharma: Consultancy, Research Funding; AstraZeneca/MedImmune: Consultancy; Incyte Corporation: Consultancy, Research Funding; Apexx Oncology: Consultancy; Roche/Genentech: Research Funding; Imago Biosciences: Research Funding; Gilead Sciences: Research Funding. Jain:Bristol Myer Squibb: Other: for advisory board participation; Takeda: Consultancy, Honoraria; CareDx: Other: Advisory Board.

Kurzfassung: Introduction: Therapeutic options for relapsed/refractory (r/r) acute myeloid leukemia (AML) and hypomethylating agent (HMA) failure higher risk myelodysplastic syndrome (MDS) are limited with a median overall survival of & lt; 6 months. Although chimeric antigen receptor (CAR) T cell therapy has revolutionized the treatment of B-cell malignancies, significant challenges exist in myeloid CAR development. PRGN-3006 UltraCAR-T are engineered using non-viral gene delivery to simultaneously express CD33 CAR, membrane bound IL-15 (mbIL15) and kill switch to be effective against AML with improved safety profile. UltraCAR-T cells are manufactured at medical center's cGMP facility using autologous T cells in & lt; 48 hours without ex vivo expansion. Methods: A Phase 1/1b first-in-human dose escalation/dose expansion clinical trial (NCT03927261) of PRGN-3006 in adult pts with r/r AML, HMA failure higher risk MDS or chronic myelomonocytic leukemia (CMML) with ≥ 5% blasts. Pts who have relapsed post allogeneic stem cell transplant (SCT) are allowed if & gt; 3 months out from transplant without evidence of active graft versus host disease (GvHD) and off immunosuppression for 6 weeks. Ps receive PRGN-3006 infusion without (Cohort 1) or with lymphodepletion (fludarabine 30mg/m 2 and cyclophosphamide 500mg/m 2 days -5 to -3; Cohort 2). Dose escalation of Cohorts 1 and 2 occur in parallel with initial clearance of Cohort 1 at each dose level (DL; Table 1). Results: As of July 25, 2021, data cut-off, 15 r/r AML pts have been treated in Cohort 1 (n=9) and Cohort 2 (n=6) with a median age of 60 years (33-77). Pts were heavily pre-treated with a median of 3 prior regimens (1-7), with 93% and 80% of pts being r/r to a HMA + venetoclax or intensive chemotherapy, respectively. Additionally, 40% of pts (n=6) had relapsed after SCT. 93% of pts were int/adv by ELN 2017 criteria (60% adverse). PRGN-3006 infusion at doses up to 1x10 6 cells/kg was well tolerated. There have been no deaths, DLTs, bone marrow aplasia, neurotoxicity or unexpected on-target/off-target toxicities related to PRGN-3006, and no use of the kill switch to date. One incidence of grade 2 GvHD was observed in a post-SCT patient (Cohort 2) on day 31, which resolved completely with corticosteroid therapy, and notably this patient responded to therapy. Cytokine release syndrome (CRS) occurred in 47% of pts (n=7; G1 in 5 pts) with only 1 transient grade 3 event (DL 1, Cohort 1) that resolved in & lt; 24 hours with tocilizumab and dexamethasone. Median onset to maximum CRS was 11 days (range 4-15 days). Peak CRP and ferritin levels occurred at a median of days 8 and 9, respectively. No significant increase in plasma levels of inflammatory cytokines, including IL-6 and TNFa, was observed post treatment. The plasma levels of IL-15 did not increase with treatment confirming mbIL15 is not shed. In Cohort 1, dose escalation through DL3 has been completed. Dose-dependent expansion of PRGN-3006 was observed in all patients with mean peak copy numbers following DL1, DL2 and DL3 in peripheral blood at approximately 600, 9,700 and 28,000 copies/µg DNA, respectively, with persistence up to 7 months post-infusion in a pt with stable disease/blast reduction. No objective responses in cohort 1 have been observed to date. In Cohort 2, dose escalation through DL2 has been completed. Expansion of PRGN-3006 was higher in Cohort 2 compared to Cohort 1 with mean peak copy numbers following DL1 and DL2 in peripheral blood at approximately 11,000 and 120,000 copies/µg DNA, respectively, and persistence 3+ months post-infusion. The objective response rate (ORR) for Cohort 2 was 50% (3/6). At DL1, 1 of 3 pts obtained CRi and was bridged to SCT and remains in a measurable residual disease negative CR 6 months post-SCT. At DL2, 2 post-SCT relapse patients also obtained response: 1 CRh with complete cytogenetic remission and NGS clearance with a remission length of 2 months; and 1 PR that lasted 3 months in a patient with isolated extramedullary leukemia (Figure 1). All 3 responders remain alive at data cut-off (5-10 months). Conclusion: PRGN-3006 UltraCAR-T cells targeting CD33 have been well tolerated with low grade CRS. In the setting of mbIL15, there has been a dose-dependent robust expansion and durable persistence of PRGN-3006 with encouraging responses (50%) in patients treated following lymphodepletion. Enrollment is ongoing to DL4, and updated safety, efficacy, PK/PD and cytokine data to be presented. Figure 1 Figure 1. Disclosures Sallman: AbbVie: Membership on an entity's Board of Directors or advisory committees; Syndax: Membership on an entity's Board of Directors or advisory committees; Intellia: Membership on an entity's Board of Directors or advisory committees; Incyte: Speakers Bureau; Kite: 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, Speakers Bureau; Magenta: Consultancy; Aprea: Membership on an entity's Board of Directors or advisory committees, Research Funding; Shattuck Labs: Membership on an entity's Board of Directors or advisory committees; Takeda: Consultancy; Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees; Agios: Membership on an entity's Board of Directors or advisory committees. Sweet: Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees; Astellas: Consultancy, Membership on an entity's Board of Directors or advisory committees; Gilead: Membership on an entity's Board of Directors or advisory committees; AROG: Membership on an entity's Board of Directors or advisory committees; Bristol Meyers Squibb: Honoraria, Membership on an entity's Board of Directors or advisory committees. Talati: AbbVie: Honoraria; BMS: Honoraria; Pfizer: Honoraria; Jazz: Speakers Bureau; Astellas: Speakers Bureau. Mishra: Novartis: Research Funding. Semnani: Precigen: Current Employment. Shah: Precigen: Current Employment, Current equity holder in publicly-traded company. Sabzevari: Precigen: Current Employment, Current equity holder in publicly-traded company; Compass Therapeutics: Current equity holder in publicly-traded company; Kinnate BioPharma: Membership on an entity's Board of Directors or advisory committees. Chakiath: Precigen: Current Employment. Lankford: Precigen: Current Employment, Current equity holder in publicly-traded company. Padron: Stemline: Honoraria; Kura: Research Funding; Incyte: Research Funding; Blueprint: Honoraria; BMS: Research Funding; Taiho: Honoraria. Kuykendall: PharmaEssentia: Honoraria; Abbvie: Honoraria; Protagonist: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Prelude: Research Funding; BluePrint Medicines: Honoraria, Speakers Bureau; Celgene/BMS: Honoraria, Speakers Bureau; Novartis: Honoraria, Speakers Bureau; Incyte: Consultancy; CTI Biopharma: Honoraria. Komrokji: Geron: Consultancy; Taiho Oncology: Membership on an entity's Board of Directors or advisory committees; Novartis: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; AbbVie: Consultancy; BMSCelgene: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; PharmaEssentia: Membership on an entity's Board of Directors or advisory committees; Acceleron: Consultancy; Jazz: Consultancy, Speakers Bureau. Lancet: AbbVie: Consultancy; Daiichi Sankyo: Consultancy; Millenium Pharma/Takeda: Consultancy; ElevateBio Management: Consultancy; Astellas: Consultancy; Agios: Consultancy; Celgene/BMS: Consultancy; BerGenBio: Consultancy; Jazz: Consultancy. Davila: Precigen: Research Funding. Bejanyan: Medexus: Consultancy, Membership on an entity's Board of Directors or advisory committees; Avrobio (Spouse disclosure): Current equity holder in publicly-traded company; Magenta: Consultancy, Membership on an entity's Board of Directors or advisory committees; Humanigen (Spouse disclosure): Consultancy, Membership on an entity's Board of Directors or advisory committees; Crispr Therapeutics (Spouse disclosure): Current equity holder in publicly-traded company; Teladoc Health (Spouse disclosure): Current equity holder in publicly-traded company; Organon (Spouse disclosure): Current equity holder in publicly-traded company; Kadmon (Spouse disclosure): Consultancy; Merck (Spouse disclosure): Current equity holder in publicly-traded company; American Well Corp (Spouse disclosure): Current equity holder in publicly-traded company; Thermo Fisher (Spouse disclosure): Current equity holder in publicly-traded company; Unitedhealth Group (Spouse disclosure): Current equity holder in publicly-traded company.

Kurzfassung: Background Successful treatment with tacrolimus (TAC) to prevent graft versus host disease (GVHD) and minimize TAC-related toxicities among allogeneic hematopoietic stem cell transplantation (alloHSCT) recipients is contingent upon achieving and maintaining plasma trough concentrations within a narrow therapeutic range. Despite standardized weight-based dosing, inter-individual variability is observed in TAC trough concentrations which may in part be attributable to pharmacogenetic variants influencing the pharmacokinetic disposition of TAC. The primary objective was to investigate the association between CYP3A4, CYP3A5, or ABCB1 genotype and the proportion of patients that attained an initial TAC trough concentration in the therapeutic range following initiation of intravenous (IV) TAC and conversion to oral (PO) TAC administration. Additional associations with clinical outcomes were also explored. Methods We retrospectively evaluated 86 patients who underwent HLA-matched (8/8) related donor alloHSCT and were prescribed a TAC-based regimen for GVHD prophylaxis between January 1, 2014 and February 28, 2020 at the Moffitt Cancer Center. Data were extracted from the Moffitt BMT Research & Analysis Information Network (BRAIN) database. Patients received TAC in combination with either sirolimus (SIRO), methotrexate (MTX), or other immunosuppressant regimen. Ideal body weight was used to dose TAC unless it was less than the patient's actual body weight. When given with SIRO, TAC targeted trough concentrations were 3 to 7 ng/ml. In patents receiving TAC plus either MTX or other regimens, the target therapeutic range was 10 to 15 ng/ml. Biobanked pre-transplant blood samples were used for CYP3A4/5 and ABCB1 genotyping. Based on the frequency of phenotypes observed, analyses were performed comparing CYP3A5 normal/intermediate (NM/IM) metabolizers to CYP3A5 poor metabolizers (PM), CYP3A4 rapid metabolizers (RM) to CYP3A4 NM/IM/PM, and ABCB1 normal function (NF) to ABCB1 intermediate/low function (IF/LF). Results Median age at time of alloHSCT was 57 years (range: 20.4-76.7); 60% were men and 83% were white. CYP3A4/5 and ABCB1 phenotypes observed in the study population are presented in Table 1. No significant associations were identified between CYP3A4, CYP3A5, or ABCB1 phenotype groups and the proportion of patients attaining initial therapeutic trough concentrations after the start of IV TAC. In transitioning from IV to PO TAC, 66 of 86 patients had evaluable data. Compared to CYP3A5 PM, CYP3A5 NM/IM were significantly less likely to attain an initial target trough concentration in the therapeutic range following PO TAC administration (40% CYP3A5 NM/IM vs 76.5% CYP3A5 PM, p=0.02). A significantly lower proportion of CYP3A4 RM attained initial target trough concentrations in the therapeutic range following the switch to PO TAC compared to CYP3A4 NM/IM/PM (43% CYP3A4 RM vs 75% CYP3A4 NM/IM/PM, p=0.049). No associations were identified with PO TAC trough concentrations and ABCB1 phenotype groups. The cumulative incidences of grades 2-4 acute GVHD (aGVHD)at day 100 among CYP3A5 NM/IM vs CYP3A5 PM were 47% and 28%, respectively (p=0.07), and for CYP3A4 RM vs CYP3A4 NM/IM/PM were 46% and 30%, respectively (p=0.16). No significant differences were seen in the incidences of chronic GVHD (cGVHD) nor in non-relapse mortality. Relapse rates at 2 years were not significantly higher among patients that were CYP3A5 NM/IM and CYP3A4 RM compared to CYP3A5 PM and CYP3A4 NM/IM/PM, respectively. Overall survival (OS) for CYP3A5 NM/IM was 52% and for PM was 78% (p=0.01). When comparing CYP3A4 groups, OS for RM was 55% and for NM/IM/PM was 76% (p=0.07) (Table 2). Conclusion The findings of the present study revealed that CYP3A4/5 genotype may play an important role in dosing of PO TAC in alloHSCT recipients, whereas ABCB1 did not significantly influence either route of TAC administration. CYP3A4/5 genotypes may also influence long term survival after transplant. Larger prospective studies are needed to confirm the impact of these genes on GVHD, relapse and survival. Figure 1 Figure 1. Disclosures Perkins: AcroTech Pharma: Research Funding. Nishihori: Karyopharm: Research Funding; Novartis: Research Funding. Bejanyan: Magenta: Consultancy, Membership on an entity's Board of Directors or advisory committees; Medexus: Consultancy, Membership on an entity's Board of Directors or advisory committees; American Well Corp (Spouse disclosure): Current equity holder in publicly-traded company; Avrobio (Spouse disclosure): Current equity holder in publicly-traded company; Crispr Therapeutics (Spouse disclosure): Current equity holder in publicly-traded company; Humanigen (Spouse disclosure): Consultancy, Membership on an entity's Board of Directors or advisory committees; Kadmon (Spouse disclosure): Consultancy; Merck (Spouse disclosure): Current equity holder in publicly-traded company; Organon (Spouse disclosure): Current equity holder in publicly-traded company; Teladoc Health (Spouse disclosure): Current equity holder in publicly-traded company; Thermo Fisher (Spouse disclosure): Current equity holder in publicly-traded company; Unitedhealth Group (Spouse disclosure): Current equity holder in publicly-traded company. Pidala: Syndax: Consultancy, Membership on an entity's Board of Directors or advisory committees; CTI Biopharma: Consultancy, Membership on an entity's Board of Directors or advisory committees, Other: Clinical trial support; Amgen: Consultancy, Membership on an entity's Board of Directors or advisory committees, Other: Clinical trial support; Regeneron: Consultancy; Incyte: Consultancy; Pharmacyclics: Other: Clinical trial support, Research Funding; BMS: Other: Clinical trial support, Research Funding; Novartis: Other: Clinical trail support; Takeda: Other: Clinical trail support; Jannssen: Other: Clinical trial support; Johnson and Johnson: Other; AbbVie: Other; BMS: Other.

Kurzfassung: BACKGROUND: Outcomes of patients with acute promyelocytic leukemia (APL) have improved; however, a number of patients, particularly those with high-risk APL, still relapse despite all-trans-retinoic acid (ATRA) and arsenic-based therapies. We present single institution outcomes of autologous (auto) and allogenic (allo) hematopoietic cell transplantation (HCT) in patients with relapsed APL. PATIENTS AND METHODS: We retrospectively reviewed outcomes in patients with relapsed APL who underwent either auto- or allo- HCT at Moffitt Cancer Center from 1990 to 2018 utilizing the clinical data obtained from BMT Research & Analysis Information Network (BRAIN). Survival data were analyzed using Kaplan-Meier estimates. RESULTS: Autologous HCT Cohort: A total of 15 received auto-HCT with a median age at HCT of 39 (range, 21-60) years. Disease status at HCT were first complete remission (CR1) in 5 (33%) and CR2 in 10 (67%). Majority of patients (13/15, 87%) received busulfan/cyclophosphamide (Bu/Cy) conditioning and remaining (2/15, 13%) Bu/Cy/etoposide. All (n=15) patients received peripheral blood (PB) stem cell grafts. Median time to neutrophil engraftment was 11 (range, 10-14) days and platelet recovery was 14 (range 9-44) days. The median progression-free survival (PFS) for auto HCT was 12.9 (95% confidence interval (CI): 1.2-24.8) months. With a median follow up of 45.1 months for surviving patients, overall survival (OS) for auto HCT was 12.9 (95%CI: 0-27.8) years. At the time analysis, 8 patients were relapse-free. Allogeneic HCT Cohort: A total of 10 patients received allo HCT with a median age of 46 (range, 22-56) years at HCT. Disease status at allo HCT was CR2 in 2, CR3 in 6, and two had refractory disease. Two patients had prior auto HCT. Donor type was HLA-identical sibling=5; one antigen-mismatched sibling=1; HLA-matched unrelated donor=3; related haploidentical=1. Seven patients received peripheral blood graft and 3 received bone marrow graft. Conditioning regimen intensity was myeloablative in 7 (fludarabine/busulfan +/- anti-thymocyte globulin=3; Bu/Cy=3; cyclophosphamide/total body irradiation=1), and reduced intensity in 3 (fludarabine/melphalan=2; fludarabine/cyclophosphamide/total body irradiation=1). Seven patients received tacrolimus-based graft-versus-host disease (GVHD) prophylaxis. Median time of neutrophil engraftment was 15 (range, 12-22) days, and platelet engraftment was 22 (range, 15-28) days. The median PFS for allo HCT was 11.9 (95%CI: 2.1-21.6) months. With a median follow up of 48.2 months for surviving patients, median OS for allo HCT was 12.4 (95%CI: 4.8-19.9) months. At the time of analysis 4 patients were relapse-free. CONCLUSIONS: In our single center analysis, auto HCT for APL resulted in a durable remission and prolonged survival. Outcomes after allo HCT were suboptimal primarily due to their heavily pretreated condition and chemotherapy resistant disease. Further research on novel conditioning regimen and relapse prevention is needed to improve the outcomes of allo HCT in APL. Figure Disclosures Lancet: Jazz Pharmaceuticals: Consultancy; Agios Pharmaceuticals: Consultancy; Daiichi-Sankyo: Consultancy; Pfizer: Consultancy. Sweet:Pfizer: Consultancy; Celgene: Speakers Bureau; Jazz: Speakers Bureau; Incyte: Research Funding; Stemline: Consultancy; Astellas: Membership on an entity's Board of Directors or advisory committees; Novartis: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Abbvie: Membership on an entity's Board of Directors or advisory committees; Agios: 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. Komrokji:JAZZ: Speakers Bureau; Novartis: Speakers Bureau; Agios: Consultancy; JAZZ: Consultancy; Incyte: Consultancy; pfizer: Consultancy; DSI: Consultancy; celgene: Consultancy. Bejanyan:Kiadis Pharma: Other: advisory board. List:Celgene: Membership on an entity's Board of Directors or advisory committees, Research Funding. Nishihori:Novartis: Research Funding; Karyopharm: Research Funding.