Abstract: The molecular pathways regulating lymphoid priming, fate, and development of multipotent bone marrow (BM) stem/progenitor cells that continuously replace thymic progenitors remain largely unknown. Herein, we show that fms-like tyrosine kinase 3 (Flt3) ligand (Fl)–deficient mice have distinct reductions in the earliest thymic progenitors in fetal, postnatal, and adult thymus. A critical role of FL in thymopoiesis was particularly evident in the absence of interleukin-7 receptor α (IL-7Rα) signaling. Fl−/−Il-7r−/− mice have extensive reductions in fetal and postnatal thymic progenitors that result in a loss of active thymopoiesis in adult mice, demonstrating an indispensable role of FL in IL-7Rα–independent fetal and adult T lymphopoiesis. Moreover, we establish a unique and critical role of FL, distinct from that of IL-7Rα, in regulation of the earliest lineage-negative (Lin−) Lin−SCA1+KIT+ (LSK) FLT3hi lymphoid-primed multipotent progenitors in BM, demonstrating a key role of FLT3 signaling in regulating the very earliest stages of lymphoid progenitors.

Abstract: Background: The standard of care (SOC) treatment (Tx) in the curative setting for patients (pts) with relapsed/refractory (R/R) large B-cell lymphoma (LBCL) after 1st-line (1L) chemoimmunotherapy (CIT) is high-dose therapy with autologous stem cell rescue (HDT-ASCT) if responsive to 2L CIT; however, as many pts do not respond to or cannot tolerate 2L CIT, or are not intended for HDT-ASCT, outcomes remain poor. Axi-cel is an autologous anti-CD19 chimeric antigen receptor (CAR) T-cell therapy approved for R/R LBCL after ≥2 prior systemic therapies. Since CAR T-cell therapy may benefit pts in earlier lines of therapy, we conducted ZUMA-7 (NCT03391466), a global, randomized, Phase 3 trial of axi-cel vs SOC in pts with 2L R/R LBCL, and report here the results of the primary analysis (PA). Methods: Eligible pts were ≥18 y with LBCL, ECOG PS 0-1, R/R disease ≤12 mo of adequate 1L CIT (including anti-CD20 monoclonal antibody and an anthracycline), and intended to proceed to HDT-ASCT. Pts were randomized 1:1 to axi-cel or SOC, stratified by 1L Tx response and 2L age-adjusted IPI (sAAIPI). In the axi-cel arm, pts received a single infusion of 2×10 6 CAR T cells/kg after conditioning (3 d; cyclophosphamide 500 mg/m 2/day and fludarabine 30 mg/m 2/day). Optional bridging Tx was limited to corticosteroids (CIT was not allowed). In the SOC arm, pts received 2-3 cycles of an investigator-selected, protocol defined, platinum-based CIT regimen; pts with partial response or complete response (CR) proceeded to HDT-ASCT. Disease assessments by PET-CT per Lugano Classification occurred at timepoints specified from randomization. Although there was no planned trial crossover between arms, pts not responding to SOC could receive CAR T-cell therapy off protocol. Axi-cel was hypothesized to result in a 50% improvement in event-free survival (EFS: time to earliest date of disease progression, death from any cause, or new lymphoma Tx) vs SOC. The PA was event-driven, and the primary endpoint was EFS by blinded central review. Key secondary endpoints, tested hierarchically, were objective response rate (ORR) and overall survival (OS; interim analysis); safety was also a secondary endpoint. Level of CAR T cells was an exploratory endpoint. Results: As of 3/18/21, 359 pts were enrolled globally. The median age was 59 y (range, 21-81; 30% ≥65 y). Overall, 74% of pts had primary refractory disease and 46% had high sAAIPI (2-3). Of 180 pts randomized to axi-cel, 170 (94%) were infused; of 179 pts randomized to SOC, 64 (36%) reached HDT-ASCT after 2L CIT. The primary endpoint of EFS was met (HR: 0.398; P & lt;.0001). At 24.9 mo median follow-up, median EFS was significantly longer with axi-cel vs SOC (8.3 mo [95% CI: 4.5-15.8] vs 2 mo [95% CI: 1.6-2.8] , respectively), and Kaplan-Meier estimates of the 24-mo EFS rates were significantly higher with axi-cel (41% vs 16%). Among randomized pts, ORR and CR rates were higher with axi-cel vs SOC (ORR: 83% vs 50%, odds ratio: 5.31 [95% CI: 3.1-8.9; P & lt;.0001]; CR: 65% vs 32%). Median OS, evaluated as a preplanned interim analysis, favored axi-cel vs SOC, although it did not meet statistical significance (not reached vs 35.1 mo, respectively; HR: 0.730; P=.027). In the SOC arm, 100 (56%) received commercially available or investigational CAR T-cell therapy off protocol as subsequent Tx. Grade ≥3 treatment-emergent adverse events occurred in 155 (91%) and 140 (83%) pts, and Tx-related deaths occurred in 1 and 2 pts in the axi-cel and SOC arms, respectively. In pts treated with axi-cel, grade ≥3 cytokine release syndrome (CRS) occurred in 11 (6%) pts (median time to onset 3 d; median duration 7 d) and grade ≥3 neurologic events (NEs) occurred in 36 (21%) pts (median time to onset 7 d; median duration 8.5 d). No grade 5 CRS or NEs occurred. Median peak CAR T-cell level was 25.8 cells/µL; median time to peak was 7 d after infusion. Conclusions: ZUMA-7, the first randomized, global, multicenter Phase 3 study of axi-cel vs 2L SOC in R/R LBCL, demonstrated a statistically significant and clinically meaningful improvement in EFS. Axi-cel showed superiority over SOC with & gt;4-fold greater median EFS, 2.5-fold greater EFS at 2 y, double the CR rate, and more than double the percentage of pts receiving definitive Tx. Safety of axi-cel was manageable and at least consistent with 3L axi-cel therapy. Axi-cel may replace CIT/HDT-ASCT as the SOC for 2L R/R LBCL. These data are reported on behalf of all ZUMA-7 investigators and contributing Kite members. Disclosures Locke: Novartis: Consultancy, Other, Research Funding; Janssen: Consultancy, Other: Scientific Advisory Role; Kite, a Gilead Company: Consultancy, Other: Scientific Advisory Role, Research Funding; Iovance Biotherapeutics: Consultancy, Other: Scientific Advisory Role; GammaDelta Therapeutics: Consultancy, Other: Scientific Advisory Role; Umoja: Consultancy, Other; Wugen: Consultancy, Other; Takeda: Consultancy, Other; Legend Biotech: Consultancy, Other; EcoR1: Consultancy; Emerging Therapy Solutions: Consultancy; Gerson Lehrman Group: Consultancy; Cowen: Consultancy; Calibr: Consultancy, Other: Scientific Advisory Role; Moffitt Cancer Center: Patents & Royalties: field of cellular immunotherapy; Cellular Biomedicine Group: Consultancy, Other: Scientific Advisory Role; BMS/Celgene: Consultancy, Other: Scientific Advisory Role; Bluebird Bio: Consultancy, Other: Scientific Advisory Role; Amgen: Consultancy, Other: Scientific Advisory Role; Allogene Therapeutics: Consultancy, Other: Scientific Advisory Role, Research Funding. Miklos: Pharmacyclics, Amgen, Kite, a Gilead Company, Novartis, Roche, Genentech, Becton Dickinson, Isoplexis, Miltenyi, Juno-Celgene-Bristol Myers Squibb, Allogene, Precision Biosciences, Adicet, Adaptive Biotechnologies: Research Funding; Adaptive Biotechnologies, Novartis, Juno/Celgene-BMS, Kite, a Gilead Company, Pharmacyclics-AbbVie, Janssen, Pharmacyclics, AlloGene, Precision Bioscience, Miltenyi Biotech, Adicet, Takeda: Membership on an entity's Board of Directors or advisory committees; Kite, a Gilead Company, Amgen, Atara, Wugen, Celgene, Novartis, Juno-Celgene-Bristol Myers Squibb, Allogene, Precision Bioscience, Adicet, Pharmacyclics, Janssen, Takeda, Adaptive Biotechnologies and Miltenyi Biotechnologies: Consultancy; Pharmacyclics: Patents & Royalties. Jacobson: Kite, a Gilead Company: Consultancy, Honoraria, Other: Travel support; Lonza: Consultancy, Honoraria, Other: Travel support; Precision Biosciences: Consultancy, Honoraria, Other: Travel support; Novartis Pharmaceuticals Corporation: Consultancy, Honoraria, Other: Travel support; Nkarta: Consultancy, Honoraria; AbbVie: Consultancy, Honoraria; Pfizer: Consultancy, Honoraria, Other: Travel support, Research Funding; Celgene: Consultancy, Honoraria, Other: Travel support; Humanigen: Consultancy, Honoraria, Other: Travel support; Axis: Speakers Bureau; Clinical Care Options: Speakers Bureau. Perales: Cidara: Honoraria; Omeros: Honoraria; Merck: Honoraria; Servier: Honoraria; Medigene: Honoraria; Takeda: Honoraria; Miltenyi Biotec: Honoraria, Other; Sellas Life Sciences: Honoraria; Kite/Gilead: Honoraria, Other; Novartis: Honoraria, Other; Incyte: Honoraria, Other; Equilium: Honoraria; Karyopharm: Honoraria; NexImmune: Honoraria; Celgene: Honoraria; Nektar Therapeutics: Honoraria, Other; MorphoSys: Honoraria; Bristol-Myers Squibb: Honoraria. Kersten: Novartis: Consultancy, Honoraria, Other: Travel support; Kite, a Gilead Company: Consultancy, Honoraria, Other: Travel support, Research Funding; Roche: Consultancy, Honoraria, Other: Travel support, Research Funding; BMS/Celgene: Consultancy, Honoraria; Takeda: Research Funding; Celgene: Research Funding; Miltenyi Biotec: Consultancy, Honoraria, Other: Travel support. Oluwole: Janssen: Consultancy; Kite, a Gilead Company: Consultancy, Research Funding; Pfizer: Consultancy; Curio Science: Consultancy. Ghobadi: Amgen: Consultancy, Research Funding; Kite, a Gilead Company: Consultancy, Honoraria, Research Funding; Atara Biotherapeutics: Consultancy; Wugen: Consultancy; Celgene: Consultancy. McGuirk: Juno Therapeutics: Consultancy, Honoraria, Research Funding; Kite/ Gilead: Consultancy, Honoraria, Other: travel accommodations, expense, Kite a Gilead company, Research Funding, Speakers Bureau; Novartis: Research Funding; Gamida Cell: Research Funding; Pluristem Therapeutics: Research Funding; Bellicum Pharmaceuticals: Research Funding; Allovir: Consultancy, Honoraria, Research Funding; Magenta Therapeutics: Consultancy, Honoraria, Research Funding; EcoR1 Capital: Consultancy; Novartis: Research Funding; Fresenius Biotech: Research Funding; Astelllas Pharma: Research Funding. Pagel: Incyte/MorphoSys: Consultancy; Gilead: Consultancy; AstraZeneca: Consultancy; Actinium Pharmaceuticals: Consultancy; Pharmacyclics/AbbVie: Consultancy; BeiGene: Consultancy; Epizyme: Consultancy; MEI Pharma: Consultancy; Kite, a Gilead Company: Consultancy. Muñoz: Targeted Oncology, OncView, Kyowa, Physicians' Education Resource, and Seagen: Honoraria; Pharmacyclics, Abbvie, Bayer, Kite, a Gilead Company, Pfizer, Janssen, Juno/Celgene, Bristol Myers Squibb, Kyowa, Alexion, Beigene, Fosun Kite, Innovent, Seagen, Debiopharm, Karyopharm, Genmab, ADC Therapeutics, Epizyme, Beigene, and Servier: Consultancy; Kite, a Gilead Company, Kyowa, Bayer, Pharmacyclics, Janssen, Seagen, Acrotech, Aurobindo, Beigene, Verastem, AstraZeneca, Celgene/Bristol Myers Squibb, Genentech, and Roche: Speakers Bureau; Bayer, Kite, a Gilead Company, Celgene, Merck, Portola, Incyte, Genentech, Pharmacyclics, Seagen, and Janssen, Millennium: Research Funding; OncView: Honoraria; Kyowa Kirin: Honoraria; Physicians' Education Resource: Honoraria. Farooq: Kite, a Gilead Company: Honoraria. Van Meerten: Kite, a Gilead Company: Honoraria; Janssen: Consultancy. Reagan: Genentech: Research Funding; Kite, a Gilead Company: Consultancy; Curis: Consultancy; Seagen: Research Funding. Sureda: Kite, a Gilead Company: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Janssen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Amgen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Sanofi: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; GSK: Consultancy, Honoraria, Speakers Bureau; Roche: Other: Support for attending meetings and/or travel; Bluebird: Membership on an entity's Board of Directors or advisory committees; Mundipharma: Consultancy; BMS/Celgene: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Support for attending meetings and/or travel, Speakers Bureau; Novartis: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; MSD: Consultancy, Honoraria, Speakers Bureau; Takeda: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Support for attending meetings and/or travel, Research Funding, Speakers Bureau. Flinn: Loxo: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; AbbVie: Consultancy, Other: All Consultancy and Research Funding payments made to Sarah Cannon Research Institute, Research Funding; Gilead Sciences: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; Forma Therapeutics: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Pfizer: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Takeda: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; Kite, a Gilead Company: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; Calithera Biosciences: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Juno Therapeutics: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; ArQule: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Karyopharm Therapeutics: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Nurix Therapeutics: Consultancy, Other: All consultancy payments made to Sarah Cannon Research Institute; Great Point Partners: Consultancy, Other: All consultancy payments made to Sarah Cannon Research Institute; BeiGene: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; Seagen: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; MorphoSys: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; Trillium Therapeutics: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Constellation Pharmaceuticals: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Unum Therapeutics: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; Janssen: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; Genentech: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; Yingli Pharmaceuticals: Consultancy, Other: All consultancy payments made to Sarah Cannon Research Institute; Curis: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Celgene: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Novartis: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; AstraZeneca: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; Roche: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; IGM Biosciences: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Iksuda Therapeutics: Consultancy, Other: All consultancy payments made to Sarah Cannon Research Institute; Verastem: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; Portola Pharmaceuticals: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Infinity Pharmaceuticals: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Rhizen Pharmaceuticals: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Forty Seven: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Incyte: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Agios: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Teva: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; TG Therapeutics: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; Merck: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Pharmacyclics LLC, an AbbVie Company: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; Acerta Pharma: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Triphase Research & Development Corp.: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Century Therapeutics: Consultancy, Other: All consultancy payments made to Sarah Cannon Research Institute; Hutchison MediPharma: Consultancy, Other: All consultancy payments made to Sarah Cannon Research Institute; Vincerx Pharma: Consultancy, Other: All consultancy payments made to Sarah Cannon Research Institute; Sarah Cannon Research Institute: Current Employment; Servier Pharmaceuticals: Consultancy, Other: All consultancy payments made to Sarah Cannon Research Institute; Yingli Pharmaceuticals: Consultancy, Other: All consultancy payments made to Sarah Cannon Research Institute; Seagen: Consultancy, Other: All consultancy payments made to Sarah Cannon Research Institute; Servier Pharmaceuticals: Consultancy, Other: All consultancy payments made to Sarah Cannon Research Institute; Unum Therapeutics: Consultancy, Other: All consultancy payments made to Sarah Cannon Research Institute, Research Funding; Johnson & Johnson: Current holder of individual stocks in a privately-held company; Seattle Genetics: Research Funding. Vandenberghe: Bristol Myers Squibb/Celgene: Consultancy; Pfizer: Research Funding; Gilead Sciences: Consultancy, Other: Travel support; Miltenyi Biotec: Consultancy; Novartis: Consultancy; Janssen: Consultancy, Research Funding; Kite, a Gilead Company: Consultancy. Song: GlaxoSmithKline: Honoraria; Takeda: Consultancy, Honoraria; Amgen: Consultancy, Honoraria; Janssen: Honoraria, Research Funding; Celgene: Consultancy, Honoraria, Research Funding; Bristol Myers Squibb: Honoraria; Kite, a Gilead Company: Honoraria; Sanofi: Honoraria. Dickinson: Novartis: Consultancy, Honoraria, Research Funding, Speakers Bureau; Takeda: Research Funding; Bristol-Myers Squibb: Consultancy, Honoraria; Celgene: Research Funding; Amgen: Honoraria; Roche: Consultancy, Honoraria, Other: travel, accommodation, expenses, Research Funding, Speakers Bureau; Gilead Sciences: Consultancy, Honoraria, Speakers Bureau; MSD: Consultancy, Honoraria, Research Funding, Speakers Bureau; Janssen: Consultancy, Honoraria. Minnema: Janssen: Consultancy; Alnylam: Consultancy; Kite/Gilead: Consultancy; Cilag: Consultancy; Celgene: Other: Travel expenses; BMS: Consultancy. Riedell: Kite/Gilead: Research Funding, Speakers Bureau; Novartis: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; BeiGene: Consultancy; Takeda: Consultancy, Membership on an entity's Board of Directors or advisory committees; Janssen: 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, Research Funding; Bayer: Membership on an entity's Board of Directors or advisory committees; Karyopharm: Consultancy, Membership on an entity's Board of Directors or advisory committees; Calibr: Research Funding; Tessa Therapeutics: Research Funding; Xencor: Research Funding; MorphoSys: Research Funding. Leslie: Karyopharm Therapeutics: Honoraria, Speakers Bureau; BeiGene: Consultancy, Honoraria, Speakers Bureau; Celgene/BMS: Consultancy, Honoraria, Speakers Bureau; Merck: Consultancy; Abbvie: Consultancy, Honoraria; Kite, a Gilead Company: Consultancy, Honoraria, Speakers Bureau; TG Therapeutics: Consultancy, Honoraria, Speakers Bureau; AstraZeneca: Consultancy, Honoraria, Speakers Bureau; Pharmacyclics: Consultancy, Honoraria, Speakers Bureau; ADC Therapeutics: Consultancy; Epizyme: Consultancy, Honoraria, Speakers Bureau; PCYC/Janssen: Consultancy, Honoraria, Speakers Bureau; Seagen: Consultancy, Honoraria, Speakers Bureau; Janssen: Consultancy, Speakers Bureau. Chaganti: Kite, a Gilead Company: Consultancy, Honoraria, Other: Travel support, Research Funding, Speakers Bureau; Novartis: Consultancy, Honoraria, Other: Travel support, Research Funding, Speakers Bureau; Takeda: Consultancy, Honoraria, Other: travel support, Research Funding, Speakers Bureau; Celgene-BMS: Consultancy, Honoraria, Other: Travel support; Atara Bio: Consultancy, Honoraria, Research Funding, Speakers Bureau; Janssen: Research Funding; Incyte: Honoraria, Speakers Bureau. Yang: Kite, a Gilead Company: Current Employment. Filosto: Tusk Therapeutics: Patents & Royalties: or other intellecular property; Gilead Sciences: Other: stock or other ownership ; Kite, a Gilead Company: Current Employment. Schupp: Gilead Sciences: Current equity holder in publicly-traded company; Kite, a Gilead Company: Current Employment, Honoraria, Other: Travel support. To: NantWorks: Ended employment in the past 24 months; Kite, a Gilead Company: Current Employment, Other: stock or other ownership . Cheng: Kite, a Gilead Company: Current Employment, Other: Travel support; Gilead Sciences: Other: stock or other ownership . Gordon: Bristol Myers Squibb: Honoraria, Research Funding; Zylem Biosciences: Patents & Royalties: Patents, No royalties. Westin: Genentech: Consultancy, Research Funding; Bristol Myers Squibb: Consultancy, Research Funding; Novartis: Consultancy, Research Funding; Kite, a Gilead Company: Consultancy, Research Funding; Curis: Research Funding; Iksuda Therapeutics: Consultancy; Umoja: Consultancy; ADC Therapeutics: Consultancy, Research Funding; AstraZeneca: Consultancy, Research Funding; MorphoSys: Consultancy, Research Funding; Morphosys: Research Funding; 47 Inc: Research Funding.

Abstract: Introduction: Limited stage nodular lymphocyte predominant Hodgkin lymphoma (NLPHL) is a highly curable malignancy with an excellent prognosis. Given disease rarity, there are few prospective studies and as a result, diverse treatment approaches are used in both the adult and pediatric populations. At BC Cancer, provincial treatment guidelines for limited stage NLPHL have largely followed that of classical HL: Prior to 2005, radiotherapy (RT) was integrated usually as combined modality therapy (CMT); after 2005, an adaptive approach using 18F-fluoro-2-deoxyglucose positron emission tomography (PET) was adopted. Herein, we evaluated the impact of using this approach. Methods: Adult ( 〉 16 years [y]) patients (pts) diagnosed with limited stage NLPHL (stage 1A, 1B or 2A, non-bulky [ 〈 10cm]) from January 1995 to February 2019 were identified in the BC Cancer Lymphoid Cancer Database. Pts were treated based on era-specific guidelines: 1995 to 2005 (CMT era), 2 cycles of ABVD (or ABVD-like chemotherapy [CHT] ) and RT, or RT alone in stage 1A high neck node disease; 2005 to present (PET era), 2 cycles of ABVD followed by interim PET (PET2). If PET2 was negative (PETneg), 2 further cycles of ABVD (after 2017, AVD alone) were given; if PET2 was positive (PETpos), RT was administered. PET scans were performed and centrally reviewed at BC Cancer. Prior to 2014, interpretation was based on the International Harmonization Project (IHP) criteria. This was subsequently replaced by the 5-point Deauville (D) scale (PETneg = DX, D1-2, PETpos = D3-5). Results: A total of 98 pts were identified. Of these, 93 (95%) received active therapy. Patient characteristics did not differ between the two eras: median age 38 y (range 16 - 82 y); male n=73 (74%); stage 2 n=43 (44%); median largest mass size 4 cm (range 2 - 9 cm). In the CMT era (n=37), all pts received active therapy: 84% were treated with ABVD (like) CHT (ABVD n=30 [including ABVD alone n=2], MOPP/ABV n=1); 6 pts with stage 1A received RT alone. In the PET era (n=61), 92% received active therapy (n=56), of which 52 received CHT (ABVD n=49, modified CVPP/ABO with bleomycin omitted n=1, R-CHOP n=2) and 4 pts were treated with RT alone. The remaining 5 pts were observed/refused therapy. With a median follow up of 7.7 y for all pts (range 0.3 - 20.5 y) (CMT era 13.5 y [3.3 - 20.5 y], PET era 5.5 y [0.3 - 13.5 y] ), the time to progression (TTP), progression free survival (PFS), overall survival (OS), and disease specific survival (DSS) at 5 y were 93%, 92%, 98%, and 99%, respectively. There was no difference in outcomes by era comparison (p 〉 0.1) or by stage (1 vs 2) (p=0.93). Overall, there have been 7 lymphoma recurrences (CMT era n=3, PET era n=4), including 3 (3%) with transformed disease (biopsy proven T cell rich B cell lymphoma n=1, presumed aggressive lymphomas based on new splenic nodules n=2). In total, there were 48/52 cases that had a PET2 scan interpreted using the D criteria, including 30 in the IHP time period that were re-reviewed: 85% were PETneg (n=41); 15% were PETpos (n=7). Four CHT treated pts did not receive a PET2 scan: RT added (CHT toxicity) n=3; death (diabetic ketoacidosis [DKA] post cycle 1 ABVD) n=1. All PETpos cases and only 4 PETneg cases (CHT toxicity n=2, PETpos by IHP criteria n=2) received RT. Considering PET-specific outcomes, the 5 y PFS and TTP were both 92% for PETneg and 80% for PETpos cases (p=0.56) (Figure 1). Three recurrences occurred in PETneg pts (DX n=1, D2 n=2), all of which had received ABVD alone but only 1 would have been solely in a RT field. The single recurrence among the PETpos cases (D5) was outside of the RT field. In the whole cohort, 9 pts have died (CMT era n=5, PET era n=4). Two deaths in the PET era were deemed related to NLPHL: 1 patient refused primary therapy and died of progressive disease and the other died during ABVD of DKA, possibly treatment related. The remaining deaths were due to other malignancies (lung n=2 [one within RT field], vulvar n=1, anaplastic large cell lymphoma n=1) or unknown causes (n=3). Conclusions: Consistent with other modern series, the outcome of pts with limited stage NLPHL is excellent with both 5 y PFS and OS exceeding 90%. Pts with an interim PETneg scan have a favorable outcome although longer follow-up is needed given the long natural history of NLPHL. This represents the largest experience of a PET-adapted approach in NLPHL and supports that ABVD alone is a viable option in selected patients with consideration of both acute and long term toxicities. Disclosures Villa: Roche, Abbvie, Celgene, Seattle Genetics, Lundbeck, AstraZeneca, Nanostring, Janssen, Gilead: Consultancy, Honoraria. Scott:Celgene: Consultancy; Janssen: Consultancy, Research Funding; Roche/Genentech: Research Funding; NanoString: Patents & Royalties: Named inventor on a patent licensed to NanoSting [Institution], Research Funding. Gerrie:Lundbeck, Seattle Genetics: Consultancy, Honoraria. Freeman:Seattle Genetics, Janssen, Amgen, Celgene, Abbvie: Consultancy, Honoraria. Pickles:TarSera: Honoraria, Other: Participated in advisory board meeting; Astellas Inc.: Research Funding; Abbvie, Sanofi: Consultancy, Honoraria. Sehn:Morphosys: Consultancy, Honoraria; TEVA Pharmaceuticals Industries: Consultancy, Honoraria; F. Hoffmann-La Roche/Genentech: Consultancy, Honoraria, Research Funding; F. Hoffmann-La Roche/Genentech: Consultancy, Honoraria, Research Funding; Astra Zeneca: Consultancy, Honoraria; Karyopharm: Consultancy, Honoraria; Merck: Consultancy, Honoraria; Celgene: Consultancy, Honoraria; Amgen: Consultancy, Honoraria; Acerta: Consultancy, Honoraria; Abbvie: Consultancy, Honoraria; Seattle Genetics: Consultancy, Honoraria; Astra Zeneca: Consultancy, Honoraria; TEVA Pharmaceuticals Industries: Consultancy, Honoraria; Lundbeck: Consultancy, Honoraria; Amgen: Consultancy, Honoraria; Seattle Genetics: Consultancy, Honoraria; Lundbeck: Consultancy, Honoraria; Kite Pharma: Consultancy, Honoraria; Kite Pharma: Consultancy, Honoraria; Acerta: Consultancy, Honoraria; Merck: Consultancy, Honoraria; Gilead: Consultancy, Honoraria; TG Therapeutics: Consultancy, Honoraria; Apobiologix: Consultancy, Honoraria; Morphosys: Consultancy, Honoraria; Abbvie: Consultancy, Honoraria; TG Therapeutics: Consultancy, Honoraria; Janssen-Ortho: Honoraria; Janssen-Ortho: Consultancy, Honoraria; Takeda: Consultancy, Honoraria; Verastem: Consultancy, Honoraria. Connors:Takeda Pharmaceuticals: Honoraria; Seattle Genetics: Honoraria, Research Funding; Bristol-Myers Squibb: Consultancy. Savage:BMS, Merck, Novartis, Verastem, Abbvie, Servier, and Seattle Genetics: Consultancy, Honoraria; Seattle Genetics, Inc.: Consultancy, Honoraria, Research Funding.

Abstract: Phenotypically and functionally distinct progenitors and developmental pathways have been proposed to exist for fetally derived B-1 and conventional B-2 cells. Although IL-7 appears to be the primary cytokine regulator of fetal and adult B lymphopoiesis in mice, considerable fetal B lymphopoiesis and postnatal B cells are sustained in the absence of IL-7; in humans, B-cell generation is suggested to be largely IL-7–independent, as severe combined immune-deficient patients with IL-7 deficiency appear to have normal B-cell numbers. However, the role of other cytokines in IL-7–independent B lymphopoiesis remains to be established. Although thymic stromal lymphopoietin (TSLP) has been proposed to be the main factor driving IL-7–independent B lymphopoiesis and to distinguish fetal from adult B-cell progenitor development in mice, recent studies failed to support a primary role of TSLP in IL-7–independent fetal B-cell development. However, the role of TSLP in IL-7–independent adult B lymphopoiesis and in particular in regulation of B-1 cells remains to be established. Here we demonstrate that, rather than TSLP, IL-7 and FLT3 ligand are combined responsible for all B-cell generation in mice, including recently identified B-1–specified cell progenitors. Thus, the same IL-7– and FLT3 ligand–mediated signal-ing regulates alternative pathways of fetal and adult B-1 and B-2 lymphopoiesis.

Abstract: The discovery of humans with monogenic disorders has a rich history of generating new insights into biology. Here we report the first human identified with complete deficiency of nuclear factor of activated T cells 1 (NFAT1). NFAT1, encoded by NFATC2, mediates calcium-calcineurin signals that drive cell activation, proliferation, and survival. The patient is homozygous for a damaging germline NFATC2 variant (c.2023_2026delTACC; p.Tyr675Thrfs∗18) and presented with joint contractures, osteochondromas, and recurrent B-cell lymphoma. Absence of NFAT1 protein in chondrocytes caused enrichment in prosurvival and inflammatory genes. Systematic single-cell–omic analyses in PBMCs revealed an environment that promotes lymphomagenesis with accumulation of naïve B cells (enriched for oncogenic signatures MYC and JAK1), exhausted CD4+ T cells, impaired T follicular helper cells, and aberrant CD8+ T cells. This work highlights the pleiotropic role of human NFAT1, will empower the diagnosis of additional patients with NFAT1 deficiency, and further defines the detrimental effects associated with long-term use of calcineurin inhibitors.