Engraftment Kinetics and Recipient Chimerism Increase to Predict Leukemia Relapse By Ptcy and Non-Ptcy Transplant

Abstract Recipient chimerism increase has been used to predict leukemia relapse in post-hematopoietic cell transplant (HCT) patients with conventional GVHD prophylaxis. However, the value of recipient chimerism increase in patients with post-transplant cyclophosphamide (PTCy) is not clear. We compared PTCy to conventional GVHD prophylaxis (non-PTCy) patients regarding engraftment kinetics and the clinical significance of the 2 chimerism parameters, increasing mixed chimerism (IMC) and degree of recipient chimerism increase at the first event (Δ increase). We studied both total and T-cell-specific chimerism. While leukemia relapse is manifested by an increase in total cell recipient chimerism, an increase in T-cell-specific recipient chimerism may be more impactful in predicting relapse because of the effect of increased T-cell-specific chimerism on the graft-versus-leukemia effect. A total of 220 patients (PTCy: 44, non-PTCy: 176) with AML, MDS, and ALL underwent HCT at our institution from January 2014 to September 2020 and were included in this study (Table). Chimerism was tested at least monthly for the first 3 months, followed by every 3 months up until 1-year post-HCT, and then every 6-12 months thereafter. Short tandem repeat or quantitative PCR were used when percent recipient chimerism was ≥5% and <5%, respectively. Cumulative incidence of competing events and Gray's test were applied for engraftment analysis. Relapse and non-relapse mortality were considered as competing risks for engraftment. Mantel-Byar test and Simon-Makuch plot with landmark analysis were used to visualize disease-free survival (DFS) curves. The Cox proportional hazards model with time-dependent covariates was performed to identify the factors affecting relapse. PTCy patients achieved complete donor chimerism (CC) in total cells earlier at a deeper level (>99%) as compared to non-PTCy patients. Deeper total cell CC (>99%) was achieved in 79.5% of PTCy vs. 51% of non-PTCy patients at day 250, while CC (>95%) was achieved in almost 90% of patients in both groups within 100 days (Figure 1A and B). In comparison, the percentage of PTCy patients achieving T-cell-specific CC was significantly higher at day 250 post-HCT: CC (>95%/>99%) was 79.7%/68.4% in PTCy patients vs. 56.1%/37.5% in non-PTCy patients (Figure 1C and D). To evaluate their impact in predicting relapse, IMC was stratified into no IMC, 1 IMC (≥1 nonconsecutive IMC), and 2 IMC (≥2 consecutive IMC), and degree of recipient chimerism increase at the first event (Δ increase) was stratified into <0.1% (no Δ increase), 0.1-1%, and ≥1%. Two IMC (total), 1 IMC (T-cell), and 2 IMC (T-cell) groups were associated with shorter DFS in non-PTCy patients but not in PTCy patients (Figure 2). One and 2 IMC groups (both total and T-cell) were associated with relapse risk in non-PTCy patients. Furthermore, 1 IMC (T-cell) in non-PTCy patients showed a strong association in relapse risk (HR 7.0 (95%CI 2.83-17.8) p<0.0001). Δ increase ≥1% (total and T-cell) and Δ increase ≥0.1% (T-cell) were associated with shorter DFS in non-PTCy patients, while only Δ increase ≥1% (T-cell) only showed a trend towards shorter DFS in PTCy patients (Figure 3). The Cox regression model showed Δ increase ≥1% in both total, and T-cell chimerism was associated with relapse risk in non-PTCy patients (HR 6.4 (95%CI 2.9-14.2) p<0.0001 and HR 7.2 (95%CI 2.9-18.1) p<0.0001, respectively). Δ increase ≥0.1% (T-cell) in non-PTCy patients was also associated with relapse risk (HR 7.2: 95%CI 2.5-20.4, p<0.0001). In comparison, no association was found between Δ increase and relapse risk in PTCy patients. This is one of the most extensive studies investigating engraftment kinetics and the association of total and T-cell recipient chimerism increase to predict leukemia relapse in PTCy and non-PTCy HCT recipients. We found that PTCy HCT recipients achieved deeper engraftment earlier as compared to non-PTCy recipients. In addition, the two chimerism parameters (IMC and Δ increase) are less reliable in predicting relapse in PTCy than non-PTCy recipients. However, other factors, such as disease type, conditioning regimen, and donor HLA disparity, may have affected engraftment kinetics and the significance of chimerism parameters. Further investigations are warranted to elucidate the impact of the engraftment kinetics and recipient chimerism increase to predict relapse, especially in the PTCy setting. Figure 1 Figure 1. Disclosures Rakszawski: SeaGen: Speakers Bureau. Naik: Takeda: Other: Virtual Advisory Board Member ; Sanofi: Other: Virtual Advisory Board Member ; Kite: Other: Virtual Advisory Board Member. Rybka: Spark Therapeutics: Consultancy; Merck: Consultancy. Claxton: Astellas: Other: Clinical Trial; Novartis: Research Funding; Astex: Research Funding; Cyclacel: Research Funding; Daiichi Sankyo: Research Funding; Incyte: Research Funding.

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Combination of NKTR-255, a Polymer Conjugated Human IL-15, with CD19 CAR T Cell Immunotherapy in a Preclinical Lymphoma Model

Blood ◽

10.1182/blood-2019-125960 ◽

2019 ◽

Vol 134 (Supplement_1) ◽

pp. 2866-2866 ◽

Cited By ~ 2

Author(s):

Cassie Chou ◽

Simon Fraessle ◽

Rachel Steinmetz ◽

Reed M. Hawkins ◽

Tinh-Doan Phi ◽

...

Keyword(s):

T Cells ◽

T Cell ◽

Research Funding ◽

Board Member ◽

Ad Hoc ◽

Advisory Board ◽

Car T Cells ◽

Car T Cell ◽

Car T ◽

Equity Ownership

Background CD19 CAR T immunotherapy has been successful in achieving durable remissions in some patients with relapsed/refractory B cell lymphomas, but disease progression and loss of CAR T cell persistence remains problematic. Interleukin 15 (IL-15) is known to support T cell proliferation and survival, and therefore may enhance CAR T cell efficacy, however, utilizing native IL-15 is challenging due to its short half-life and poor tolerability in the clinical setting. NKTR-255 is a polymer-conjugated IL-15 that retains binding affinity to IL15Rα and exhibits reduced clearance, providing sustained pharmacodynamic responses. We investigated the effects of NKTR-255 on human CD19 CAR T cells both in vitro and in an in vivo xenogeneic B cell lymphoma model and found improved survival of lymphoma bearing mice receiving NKTR-255 and CAR T cells compared to CAR T cells alone. Here, we extend upon these findings to further characterize CAR T cells in vivo and examine potential mechanisms underlying improved anti-tumor efficacy. Methods CD19 CAR T cells incorporating 4-1BB co-stimulation were generated from CD8 and CD4 T cells isolated from healthy donors. For in vitro studies, CAR T cells were incubated with NKTR-255 or native IL-15 with and without CD19 antigen. STAT5 phosphorylation, CAR T cell phenotype and CFSE dilution were assessed by flow cytometry and cytokine production by Luminex. For in vivo studies, NSG mice received 5x105 Raji lymphoma cells IV on day (D)-7 and a subtherapeutic dose (0.8x106) of CAR T cells (1:1 CD4:CD8) on D0. To determine optimal start date of NKTR-255, mice were treated weekly starting on D-1, 7, or 14 post CAR T cell infusion. Tumors were assessed by bioluminescence imaging. Tumor-free mice were re-challenged with Raji cells. For necropsy studies mice received NKTR-255 every 7 days following CAR T cell infusion and were euthanized at various timepoints post CAR T cell infusion. Results Treatment of CD8 and CD4 CAR T cells in vitro with NKTR-255 resulted in dose dependent STAT5 phosphorylation and antigen independent proliferation. Co-culture of CD8 CAR T cells with CD19 positive targets and NKTR-255 led to enhanced proliferation, expansion and TNFα and IFNγ production, particularly at lower effector to target ratios. Further studies showed that treatment of CD8 CAR T cells with NKTR-255 led to decreased expression of activated caspase 3 and increased expression of bcl-2. In Raji lymphoma bearing NSG mice, administration of NKTR-255 in combination with CAR T cells increased peak CAR T cell numbers, Ki-67 expression and persistence in the bone marrow compared to mice receiving CAR T cells alone. There was a higher percentage of EMRA like (CD45RA+CCR7-) CD4 and CD8 CAR T cells in NKTR-255 treated mice compared to mice treated with CAR T cells alone and persistent CAR T cells in mice treated with NKTR-255 were able to reject re-challenge of Raji tumor cells. Additionally, starting NKTR-255 on D7 post T cell infusion resulted in superior tumor control and survival compared to starting NKTR-255 on D-1 or D14. Conclusion Administration of NKTR-255 in combination with CD19 CAR T cells leads to improved anti-tumor efficacy making NKTR-255 an attractive candidate for enhancing CAR T cell therapy in the clinic. Disclosures Chou: Nektar Therapeutics: Other: Travel grant. Fraessle:Technical University of Munich: Patents & Royalties. Busch:Juno Therapeutics/Celgene: Consultancy, Equity Ownership, Research Funding; Kite Pharma: Equity Ownership; Technical University of Munich: Patents & Royalties. Miyazaki:Nektar Therapeutics: Employment, Equity Ownership. Marcondes:Nektar Therapeutics: Employment, Equity Ownership. Riddell:Juno Therapeutics: Equity Ownership, Patents & Royalties, Research Funding; Adaptive Biotechnologies: Consultancy; Lyell Immunopharma: Equity Ownership, Patents & Royalties, Research Funding. Turtle:Allogene: Other: Ad hoc advisory board member; Novartis: Other: Ad hoc advisory board member; Humanigen: Other: Ad hoc advisory board member; Nektar Therapeutics: Other: Ad hoc advisory board member, Research Funding; Caribou Biosciences: Equity Ownership, Membership on an entity's Board of Directors or advisory committees; T-CURX: Membership on an entity's Board of Directors or advisory committees; Juno Therapeutics: Patents & Royalties: Co-inventor with staff from Juno Therapeutics; pending, Research Funding; Precision Biosciences: Equity Ownership, Membership on an entity's Board of Directors or advisory committees; Eureka Therapeutics: Equity Ownership, Membership on an entity's Board of Directors or advisory committees; Kite/Gilead: Other: Ad hoc advisory board member.

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Engraftment Kinetics After Alimtuzumab-Based Allogeneic Stem Cell Transplant (SCT): Full Donor T-Cell Chimerism Did Not Predict for Acute Graft Versus Host Disease (GVHD) or CMV Reactivation

Blood ◽

10.1182/blood.v120.21.4162.4162 ◽

2012 ◽

Vol 120 (21) ◽

pp. 4162-4162

Author(s):

Henry C. Fung ◽

Muhammed Alikhan ◽

Lela Buckingham ◽

John J. Maciejewski ◽

Reem Karmali ◽

...

Keyword(s):

T Cell ◽

Acute Gvhd ◽

Stem Cell Transplant ◽

Mixed Chimerism ◽

Cell Transplant ◽

Allogeneic Stem Cell Transplant ◽

Graft Versus Host ◽

Gvhd Prophylaxis ◽

Cmv Reactivation

Abstract Abstract 4162 Background: Graft versus host disease (GVHD) remains the leading cause of the treatment failures following an otherwise successful allogeneic Stem Cell Transplant. Alemtuzumab – based prophylactic regimens is evolving as an important option for prevention of this devastating complication. Multiple phase II studies suggested that patients who received Alemtuzumab –containing GHVD prophylactic regimens tends to have less acute GVHD though the utility is limited by increased incidence of mixed chimerism often requiring donor lymphocytes infusion and cytomegalovirus reactivation. Hypothesis: We hypothesize that if we could identify an optimal dose of Alemtuzumab; we could maintain the benefit of lowering the incidence of GVHD and also minimize mixed chimerism and CMV reactivation following the transplant. Method: To test our hypothesis, we conducted a pilot study utilizing the combination of Alemtuzumab (20 Related Donor: 30 mg on Day -1; 10 Unrelated donor: 30 mg daily on Day -2 & Day -1) and cyclosporine as GVHD prophylaxis. Between 5/11 and 5/12, 28 pts were included in the study. There were 15 females and 13 males. The diagnosis included 16 AML, 3 NHL, 2 MDS, 1 CML, 1 CLL, 1 ALL, 1 HD, 1 PLL, 1 MPD and 1 MM. Conditioning regimens consisted of Fludarabine/Melphalan in 20, Fludarabine/Busulfan in 5, TBI/Cy in 2 and Fludarabine/Clofarabine in 1. Upon achievement of engraftment, we monitor CMV by PCR weekly and engraftment by Short tandem repeat (STR) monthly with T-cell and Myeloid subsets analysis. Results: 26/28 pts achieved neutrophils engraftment except 1 died shortly after SCT from heart failure and 1 experienced primary graft failure with day 30 STR showing only 3% donor T-cell chimerism. On Day 30 post-SCT, all evaluable pts had predominately donor T-cell (median 99%; 19/27 (70%) ≥ 99%; range 82 to > 99%) and Myeloid Chimerism (24/26 (92%) ≥ 99% except one pt who developed rapidly progressive leukemia phase PTLC after transplant. 25 pts (89%) survived beyond Day 90 post-SCT and have engraftment data available for analysis. On Day 90 analysis, while most pts maintain predominant donor myeloid chimerism (> 95%; median 99%); only 10/25 (40%) had maintained 99% donor T-cell chimerism. In addition, 76% pts had their T-cell donor chimerism worsened by Day 90 when compared with Day 30 analysis (9 pts dropped below 80%; range 8–75%). On the other hand, no pt developed secondary graft failure. 5 pts (17%) developed acute GVHD with only 1 (4%) Grade IV aGVHD. 8 pts (29%) developed CMV reactivation within day 100 post-SCT. Full donor T-cell chimerism did not predict for GVHD or CMV reactivation. With longer follow up, some pts' have donor T-Cell chimerism increased with tapering of immunosuppressive therapy with or without GVHD or after receiving DLI. Conclusion: 1. Our preliminary data suggested that using a lower dose of Alemtuzumab (30 mg for RD and 60 mg for MUD) as GVHD prophylaxis is effective to prevent GVHD though still associated with high incidence of CMV reactivation. 2. Most pts achieve predominant Donor T cell chimerism on day 30 though many worsen on subsequent follow-up. 3. Although it appears that there's no impact on durability of engraftment, longer follow-up is required to determine the impact on relapse, chronic GVHD and survival. Disclosures: Fung: Genzyme: Honoraria. Off Label Use: Alemtuzumab for GVHD prophylaxis.

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Phase I Study of Yttrium-90 Labeled ANTI-CD25 (aTac) Monoclonal Antibody PLUS BEAM for Autologous Hematopoietic Cell Transplantation (AHCT) in Patients with Mature T-Cell NON-Hodgkin Lymphoma, the "a-TAC-BEAM Regimen"

Blood ◽

10.1182/blood-2020-141114 ◽

2020 ◽

Vol 136 (Supplement 1) ◽

pp. 10-11

Author(s):

Jasmine Zain ◽

Jennifer Simpson ◽

Joycelynne Palmer ◽

Jeffrey Wong ◽

Savita Dandapani ◽

...

Keyword(s):

Monoclonal Antibody ◽

T Cell ◽

Research Funding ◽

Cell Lymphoma ◽

Conditioning Regimen ◽

Advisory Board ◽

T Cell Lymphoma ◽

Cell Transplant ◽

Board Meeting ◽

Yttrium 90

Background: Peripheral T cell lymphomas (PTCL) have a poor prognosis with current treatment regimens. High-dose chemotherapy followed by autologous stem cell transplant (ASCT) has been used as a consolidation strategy in remission states (CR1 or above) endorsed by the NCCN guidelines in appropriate patients. 5-year DFS is reported at 70% for alk -ve anaplastic large cell lymphoma (ALCL) and 30-40% for most other histologies (D'Amore et al, 2012, JCO). It is also performed in the relapsed settings if no previous ASCT performed and allogeneic transplant is not an option. CD25 is a targetable protein expressed differentially in PTCL and antibody based anti-CD25 therapies are efficacious in PTCL i.e denileukin diftitox (Foss et al Blood 2006, Dang et al, BJH 2006) , monoclonal antibody dacluzimab (Waldman et al 1995 Blood). Yttrium-90 (90Y) labeled chimeric antiCD25 antibody basiliximab emits beta particles and has been shown to inhibit the growth of human ALCL tumors and increase survival in SUDHL-1 xenograft mice (Zhang et al 2009 Cancer Biother Radiopharm). Previous investigations at COH by Raubitschek, Colcher et al established a safe does of Yttrium-90 (90Y) labeled basiliximab at 0.4mCi/kg in combination with BEAM. This is a phase 1 clinical trial of a novel conditioning regimen that includes the use of Yttrium-90 (90Y) labeled basiliximab with BEAM chemotherapy for PTCL patients eligible for ASCT. The trial utilizes a modified version of the rolling 6 design (Skolnik et al) to test 3 dose levels of Yttrium-90 (90Y) Basiliximab i.e 0.4mCi/kg, 0.5miC/kg and 0.6mCi/kg with the primary objective of evaluating the safety and tolerability of this combination and to establish the MTD. Secondary objectives include estimating incidence of relapse, OS, PFS, NRM at day 100, 1 year and 2 years post-transplant. Patients and Methods: Dose limiting toxicity (DLT) is defined according to the Bearman and CTCAE 4.03 scales, the latter for hematologic toxicity. The study/treatment schema is shown in Figure 1. Results: From 07/29/2015 to 06/10/2020, 20 patients underwent ASCT on this trial; n=4 at 0.4mCi/kg n=4 at 0.5mCi/kg and n=12 at 0.6mCi/kg. Median age at ASCT was 51 years (range: 18-76), and histologies included; PTCL-nos (n=10); alk-ve ALCL (n=5); angioimmunoblastic T-cell lymphoma (n=3); and intestinal T-cell lymphoma (n=2). Disease status at ASCT were CR1 in18, CR2 in 2 patients. Median number of prior therapies was 1 (range: 1-4). At a median follow-up of 17.1 months (range: 0.9-26.2), 12 patients remain in remission, 8 have relapsed out of which 5 have died of progressive lymphoma. OS was 100% (95% CI: N/A) at 100-days, and 83% (95% CI: 57-94) at 1 year. Non-relapse Mortality was 0% at both 100-days and 1-year. All patients successfully engrafted with the median days to ANC >= 500/ul was 10 (range: 10 - 21), and days to PLT >= 20,000/ul: 13 (12 - 92). Overall, no dose limiting toxicities were experienced. The most common/highest grade toxicity experienced (per Bearman Scale) was grade 2 stomatitis, which was seen in 3 patients at 0.4mCi/kg; 4 patients at 0.5 mCi/kg, and 7 at0.6mCi/kg. The only other toxicities seen were grade 2 GI in 2 patients at 0.4mCi/kg, and grade 2 bladder in one patient at 0.6mCi/kg dose.. Toxicities >grade 2 were not seen. Conclusion: aTac- BEAM appears to be safe as an ASCT conditioning regimen for PTCL with no increased toxicity as compared to the historical toxicities seen with BEAM alone in this patient population (D'Amore 2012 J of Clin Onc). The dose level 0.6mCi/kg will likely be the recommended phase II dose. An expanded phase is planned to evaluate the efficacy of this regimen followed by a randomized trial of BEAM alone plus a combination of aTac- BEAM. Figure 1 Disclosures Zain: Mundi Pharma: Research Funding; Seattle Genetics: Research Funding; Kyowa Kirin: Research Funding. Herrera:Gilead Sciences: Consultancy, Research Funding; Seattle Genetics: Consultancy, Research Funding; Immune Design: Research Funding; AstraZeneca: Research Funding; Karyopharm: Consultancy; Pharmacyclics: Research Funding; Genentech, Inc./F. Hoffmann-La Roche Ltd: Consultancy, Research Funding; Bristol Myers Squibb: Consultancy, Other: Travel, Accomodations, Expenses, Research Funding; Merck: Consultancy, Research Funding. Salhotra:Kadmon: Membership on an entity's Board of Directors or advisory committees; Celgene: Research Funding. Nakamura:NapaJen Pharma: Consultancy; Celgene: Other: Support on seminar; Magenta Therapeutics: Other: Advisory board meeting; Viracor: Consultancy; Merck: Other: advisory board meeting; Alexion: Other: Support on a meeting presentation; Kyowa-Kirin: Other: Support on a meeting presentation; Kadmon Corporation: Other: Advisory board meeting. OffLabel Disclosure: Yittrium labelled Basiliximab

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Identification of Two CAR T-Cell Populations Associated with Complete Response or Progressive Disease in Adult Lymphoma Patients Treated with Axi-Cel

Blood ◽

10.1182/blood-2019-130815 ◽

2019 ◽

Vol 134 (Supplement_1) ◽

pp. 779-779 ◽

Cited By ~ 2

Author(s):

Zinaida Good ◽

Jay Y. Spiegel ◽

Bita Sahaf ◽

Meena B. Malipatlolla ◽

Matthew J. Frank ◽

...

Keyword(s):

T Cells ◽

T Cell ◽

Board Of Directors ◽

Research Funding ◽

Advisory Board ◽

Advisory Committees ◽

Car T Cells ◽

Scientific Advisory Board ◽

Car T ◽

Scientific Advisory

Axicabtagene ciloleucel (Axi-cel) is an autologous anti-CD19 chimeric antigen receptor (CAR) T-cell therapy approved for the treatment of relapsed or refractory diffuse large B-cell lymphoma (r/r DLBCL). Long-term analysis of the ZUMA-1 phase 1-2 clinical trial showed that ~40% of Axi-cel patients remained progression-free at 2 years (Locke et al., Lancet Oncology 2019). Those patients who achieved a complete response (CR) at 6 months generally remained progression-free long-term. The biological basis for achieving a durable CR in patients receiving Axi-cel remains poorly understood. Here, we sought to identify CAR T-cell intrinsic features associated with CR at 6 months in DLBCL patients receiving commercial Axi-cel at our institution. Using mass cytometry, we assessed expression of 33 surface or intracellular proteins relevant to T-cell function on blood collected before CAR T cell infusion, on day 7 (peak expansion), and on day 21 (late expansion) post-infusion. To identify cell features that distinguish patients with durable CR (n = 11) from those who developed progressive disease (PD, n = 14) by 6 months following Axi-cel infusion, we performed differential abundance analysis of multiparametric protein expression on CAR T cells. This unsupervised analysis identified populations on day 7 associated with persistent CR or PD at 6 months. Using 10-fold cross-validation, we next fitted a least absolute shrinkage and selection operator (lasso) model that identified two clusters of CD4+ CAR T cells on day 7 as potentially predictive of clinical outcome. The first cluster identified by our model was associated with CR at 6 months and had high expression of CD45RO, CD57, PD1, and T-bet transcription factor. Analysis of protein co-expression in this cluster enabled us to define a simple gating scheme based on high expression of CD57 and T-bet, which captured a population of CD4+ CAR T cells on day 7 with greater expansion in patients experiencing a durable CR (mean±s.e.m. CR: 26.13%±2.59%, PD: 10.99%±2.53%, P = 0.0014). In contrast, the second cluster was associated with PD at 6 months and had high expression of CD25, TIGIT, and Helios transcription factor with no CD57. A CD57-negative Helios-positive gate captured a population of CD4+ CAR T cells was enriched on day 7 in patients who experienced progression (CR: 9.75%±2.70%, PD: 20.93%±3.70%, P = 0.016). Co-expression of CD4, CD25, and Helios on these CAR T cells highlights their similarity to regulatory T cells, which could provide a basis for their detrimental effects. In this exploratory analysis of 25 patients treated with Axi-cel, we identified two populations of CD4+ CAR T cells on day 7 that were highly associated with clinical outcome at 6 months. Ongoing analyses are underway to fully characterize this dataset, to explore the biological activity of the populations identified, and to assess the presence of other populations that may be associated with CAR-T expansion or neurotoxicity. This work demonstrates how multidimensional correlative studies can enhance our understanding of CAR T-cell biology and uncover populations associated with clinical outcome in CAR T cell therapies. This work was supported by the Parker Institute for Cancer Immunotherapy. Figure Disclosures Muffly: Pfizer: Consultancy; Adaptive: Research Funding; KITE: Consultancy. Miklos:Celgene: Membership on an entity's Board of Directors or advisory committees; BMS: Membership on an entity's Board of Directors or advisory committees; Kite-Gilead: Membership on an entity's Board of Directors or advisory committees, Research Funding; AlloGene: Membership on an entity's Board of Directors or advisory committees; Precision Bioscience: Membership on an entity's Board of Directors or advisory committees; Miltenyi Biotech: Membership on an entity's Board of Directors or advisory committees; Becton Dickinson: Research Funding; Adaptive Biotechnologies: Membership on an entity's Board of Directors or advisory committees; Novartis: Membership on an entity's Board of Directors or advisory committees, Research Funding; Juno: Membership on an entity's Board of Directors or advisory committees. Mackall:Vor: Other: Scientific Advisory Board; Roche: Other: Scientific Advisory Board; Adaptimmune LLC: Other: Scientific Advisory Board; Glaxo-Smith-Kline: Other: Scientific Advisory Board; Allogene: Equity Ownership, Membership on an entity's Board of Directors or advisory committees; Apricity Health: Equity Ownership, Membership on an entity's Board of Directors or advisory committees; Unum Therapeutics: Equity Ownership, Membership on an entity's Board of Directors or advisory committees; Obsidian: Research Funding; Lyell: Consultancy, Equity Ownership, Other: Founder, Research Funding; Nektar: Other: Scientific Advisory Board; PACT: Other: Scientific Advisory Board; Bryologyx: Other: Scientific Advisory Board.

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Absolute Lymphocyte Count (ALC) Less Than 100 Predicts Adverse Transplant Outcomes with Rabbit Thymoglobulin in Patients Undergoing Matched Unrelated Allogeneic Hematopoietic Stem Cell Transplantation

Blood ◽

10.1182/blood-2019-125437 ◽

2019 ◽

Vol 134 (Supplement_1) ◽

pp. 4527-4527

Author(s):

Dipenkumar Modi ◽

Malini Surapaneni ◽

Seongho Kim ◽

Lois Ayash ◽

Asif Alavi ◽

...

Keyword(s):

T Cell ◽

Relapse Rate ◽

Peripheral Blood ◽

Conditioning Regimen ◽

Advisory Board ◽

Hematopoietic Stem ◽

Post Transplant ◽

Transplant Outcomes ◽

Gvhd Prophylaxis

Introduction: Rabbit thymoglobulin, an in-vivo T-cell depleting agent, is widely used as a part of GVHD prophylaxis regimen. Current dosing of thymoglobulin is often weight based and does not consider patient related factors. This results in highly variable exposure of thymoglobulin. Although higher doses (>7mg/kg) of thymoglobulin have shown to reduce the risk of GVHD, it is associated with increased rate of opportunistic infections and disease recurrence. Conversely, lower dose (2.5mg/kg) of thymoglobulin is associated with increased risk of GVHD. Thus, optimum dosing of thymoglobulin remains undefined. We hypothesized that recipient peripheral blood ALC on the first day of thymoglobulin infusion would interact with the dose of thymoglobulin administered and predict post-transplant outcomes. We plan to identify association of thymoglobulin dose with the ALC on the first day of thymoglobulin. Methods: We retrospectively evaluated clinical outcomes of adult patients (pts) who underwent matched unrelated donor AHSCT and received tacrolimus, mycophenolate (cellcept) and thymoglobulin as GVHD prophylaxis. Thymoglobulin was given at a total dose of 4.5mg/kg in divided fashion (0.5mg/kg on day -3, 1.5mg/kg on day -2 and 2.5mg/kg on day -1). The objectives were to determine rate of GVHD, overall survival (OS), relapse-free survival (RFS), relapse rate and non-relapse mortality (NRM) following AHSCT using Cox proportional hazard regression and competing risk models. Results: Between January 2005 and December 2017, 217 pts underwent AHSCT. The most common indications for AHSCT were AML (n=95, 44%), MDS (n=57, 26%), non-Hodgkin's lymphoma (n=23, 11%), and ALL (n=22, 10%). Median age of pts was 60 years (range, 18-79). All pts received peripheral blood stem cells. Ninety-eight pts (45%) received full intensity conditioning regimen and 119 pts (55%) received reduced intensity regimen. The median ALC on the first day of thymoglobulin administration was 200 K/cubic millimeter. The 6-month cumulative incidence rate (CIR) of grade III-IV acute GVHD was 14.8% and the 2-year CIR of chronic extensive GVHD was 35.4%. With a median follow up of 3.82 years for surviving patients, the 2-year RFS, OS, relapse and NRM were 50%, 57.1, 20.1%, and 30.2%, respectively. CMV and EBV reactivation rates were 37% and 11%, respectively. Four pts developed CMV disease. By our lowest ALC cutoff of 100 K/cubic millimeter, pts were divided into two groups (ALC ≤ 100 vs. ALC > 100). Multivariable analysis revealed that ALC > 100 was associated with significantly superior OS (HR 0.51, 95% CI 0.33-0.79, p=0.002), RFS (HR 0.49, 95% CI 0.33-0.74, p=0.001) and lower NRM (SHR 0.57, 95% CI 0.34-0.97, p=0.038) and marginally lower relapse rate (SHR 0.57, 95% CI 0.31-1.05, p=0.070). In addition, higher infused total nucleated cells was associated with higher NRM (SHR 1.70, 95% CI 1.02-2.83, p=0.041). No impact of disease risk index, KPS, conditioning regimen, infused CD34 cells on NRM, relapse, RFS or OS was observed. Conclusion: Our study indicates that ALC ≤ 100 is associated with adverse post-transplant outcomes when thymoglobulin dose of 4.5mg/kg is used for in-vivo T cell depletion. This finding may indicate that in pts with lower ALC, thymoglobulin dose may need to be adjusted to optimize its efficacy and avoid toxicities. In the future prospective studies, which evaluate dose reduction of thymoglobulin in pts with low ALC need to be planned to confirm these results. Disclosures Deol: Agios: Other: Advisory board; Novartis: Other: Advisory board; Kite: Other: Advisory board.

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Outcomes Following Intolerance to Tacrolimus/Sirolimus for Graft-Versus-Host Disease Prophylaxis in Allogeneic Hematopoietic Stem Cell Transplant

Blood ◽

10.1182/blood-2019-127370 ◽

2019 ◽

Vol 134 (Supplement_1) ◽

pp. 5673-5673

Author(s):

Sayeef Mirza ◽

Ankita Tandon ◽

Dakota Jenneman ◽

Shu Cao ◽

Ambuj Kumar ◽

...

Keyword(s):

Graft Versus Host Disease ◽

Research Funding ◽

Categorical Variables ◽

Cell Transplant ◽

Host Disease ◽

Graft Versus Host ◽

Allogeneic Hct ◽

Gvhd Prophylaxis ◽

Days Of Therapy ◽

Grade Ii

INTRODUCTION: Graft-versus-host disease (GVHD) is a major complication of allogeneic hematopoietic cell transplant (HCT) resulting in significant morbidity and mortality. The combination of tacrolimus and sirolimus (TAC/SIR) has emerged as a GVHD prophylaxis platform preferred by many institutions given its association with rapid engraftment and acceptable transplant-related toxicity. However, overlapping toxicities between the two drugs can lead to intolerance and premature discontinuation in some patients. There is limited literature describing outcomes and subsequent management of such patients. The goal of this study is to investigate the clinical outcomes of patients becoming intolerant to the combination of TAC/SIR prophylaxis. METHODS: We retrospectively evaluated consecutive adult patients (n=100) at the Moffitt Cancer Center who received allogeneic HCT with TAC/SIR for GVHD prophylaxis in 2018. TAC/SIR intolerance was defined as discontinuation due to the toxicity of either TAC or SIR before post-transplant day 100. Survival analyses were estimated from the time of transplant with the Kaplan-Meier method and compared using the log-rank test. Patients intolerant of this prophylaxis regimen were compared to patients who completed >100 days of therapy, using Mann-Whitney U test for continuous variables and Pearson Chi-square tests for categorical variables. All statistical analyses were performed using SPSS v25 and NCSS v11. RESULTS: Demographics and clinical characteristics of all patients are summarized in Table 1A. TAC/SIR intolerance occurred in 25% (24 discontinued TAC, 1 discontinued SIR) of patients at a median duration of therapy of 19 days (range 4-92). The most common TAC/SIR toxicity (Table 1B) was acute kidney injury (AKI, n=11, 44%), followed by thrombotic microangiopathy (TMA, n=3, 12%). Baseline metabolic and clinical variables including creatinine, liver function, and conditioning intensity were not predictive of TAC-SIR intolerance. At a median follow-up of 10 months, the median overall survival (OS) for patients intolerant of TAC/SIR was 10 months versus was not reached for the patients without intolerance (HR 5.42; 95% CI 1.71-17.14; p<0.001). The 1-year PFS was 16% (95% CI 0% - 42%) vs 75% (95% CI 65% - 86%) and OS was 35% (95% CI 8% - 63%) vs. 79% (95% CI 68% - 90%) for patients who were TAC/SIR-intolerant compared to those who were TAC/SIR-tolerant (p<0.01) (Figure 1A). The cumulative incidence (CuI) of non-relapse mortality (NRM) at 1 year in patients intolerant of TAC/SIR was 47% (95% CI: 28% - 81%) and in patients tolerant of TAC/SIR was 4.4% (95% CI: 1.5% - 14%), (p<0.001). The Cul of relapse at 1 year was 45% (95% CI: 20% - 100%) in patients who were TAC/SIR-intolerant compared to 18% (95% CI: 10% - 30%) in patients who tolerated TAC/SIR (p=0.07) (figure 1B). Overall, 31 patients (31%) developed grade II-IV acute GVHD (aGVHD). The Cul of grade II-IV aGVHD at 100 days in patients who were TAC/SIR-intolerant was 29% (95% CI 15% - 58%) compared to 17% (95% CI 10% - 29%) in patients who tolerated TAC/SIR, (p=0.38). The Cul of cGVHD at 1 year in patients who were TAC/SIR-intolerant was 44% (95% CI: 25% - 79%) compared to 52% (95% CI: 40% - 68%) in patients who were TAC/SIR-tolerant (p=0.89). CONCLUSIONS: Outcomes for patients completing over 100 days of TAC/SIR for GVHD prophylaxis following allogeneic HCT are favorable. However, early intolerance of TAC/SIR GVHD prophylaxis occurred in 25% of allogeneic HCT in 2018 alone and predicted a poor prognosis with increased NRM and overall mortality, largely from drug-related toxicities. Notably, premature discontinuation of TAC/SIR did not contribute to higher subsequent risks of GVHD. Strategies to mitigate the risks of TAC/SIR toxicity are warranted. Future studies are also needed to identify the optimal GVHD prophylactic regimen for patients after TAC/SIR intolerance. Disclosures Nishihori: Novartis: Research Funding; Karyopharm: Research Funding. Bejanyan:Kiadis Pharma: Other: advisory board.

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Increased Early Mortality after Fludarabine and Melphalan Conditioning with Peripheral Blood Grafts in Haploidentical SCT with Post-Transplant Cyclophosphamide

Blood ◽

10.1182/blood-2019-129872 ◽

2019 ◽

Vol 134 (Supplement_1) ◽

pp. 4496-4496 ◽

Cited By ~ 1

Author(s):

Luke Eastburg ◽

David A. Russler-Germain ◽

Ramzi Abboud ◽

Peter Westervelt ◽

John F. DiPersio ◽

...

Keyword(s):

Bone Marrow ◽

Stem Cell ◽

T Cell ◽

Board Of Directors ◽

Research Funding ◽

Early Mortality ◽

Cell Transplant ◽

Advisory Committees ◽

Post Transplant ◽

Equity Ownership

The use of post-transplant cyclophosphamide (PTCy) in the context of haploidentical stem cell transplant (haplo-SCT) has led to drastically reduced rates of Graft-vs-Host (GvH) disease through selective depletion of highly allo-reactive donor T-cells. Early trials utilized a reduced-intensity Flu/Cy/TBI preparative regimen and bone marrow grafts; however, relapse rates remained relatively high (Luznik et al. BBMT. 2008). This led to the increased use of myeloablative (MA) regimens for haplo-SCT, which have been associated with decreased relapse rates (Bashey et al. J Clin Oncol. 2013). Most studies have used a MA total body irradiation (TBI) based regimen for haplo-SCT. Preparative regimens using fludarabine and melphalan (FluMel), with or without thiotepa, ATG, and/or low dose TBI have also been reported using bone marrow grafts. Reports on the safety and toxicity of FluMel in the haplo-SCT setting with PTCy and peripheral blood stem cell (PBSC) grafts are lacking. In this two-center retrospective analysis, the safety/toxicity of FluMel as conditioning for haplo-SCT was evaluated. We report increased early mortality and toxicity using standard FluMel conditioning and PBSC grafts for patients undergoing haplo-SCT with PTCy. 38 patients at the University of Rochester Medical Center and the Washington University School of Medicine underwent haplo-SCT with FluMel conditioning and PBSC grafts between 2015-2019. Outcomes were measured by retrospective chart review through July 2019. 34 patients (89.5%) received FluMel(140 mg/m2). Two patients received FluMel(100 mg/m2) and two patients received FluMel(140 mg/m2) + ATG. The median age at time of haplo-SCT was 60 years (range 21-73). 20 patients were transplanted for AML, eight for MDS, two for PMF, two for NHL, and five for other malignancies. The median Hematopoietic Cell Transplantation-specific Comorbidity Index (HCT-CI) score was 4 (≥3 indicates high risk). 11 patients had a history of prior stem cell transplant, and 16 patients had active disease prior to their haplo-SCT. Seven patients had sex mismatch with their stem cell donor. Median donor age was 42 (range 21-71). 20 patient deaths occurred by July 2019 with a median follow up of 244 days for surviving patients. Nine patients died before day +100 (D100, "early mortality"), with a D100 non-relapse mortality (NRM) rate of 24%. Median overall and relapse free survival (OS and RFS, respectively) were 197 days (95% CI 142-not reached) and 180 days (95% CI 141-not reached), respectively, for the entire cohort. The 1 year OS and NRM were 29% and 50%. The incidence of grades 2-4cytokine release syndrome (CRS) was 66%, and 52% of these patients were treated with tocilizumab. CRS was strongly associated with early mortality, with D100 NRM of 36% in patients with grade 2-4 CRS compared to 0% in those with grade 0-1. The incidence of acute kidney injury (AKI) was 64% in patients with grade 2-4 CRS, and 8% in those without (p < 0.001). 28% of patients with AKI required dialysis. Grade 2-4 CRS was seen in 54% of patients in remission prior to haplo-SCT and in 92% of those with active disease (p = 0.02). Of the 9 patients with early mortality, 89% had AKI, 44% needed dialysis, and 100% had grade 2-4 CRS, compared to 31%, 10%, and 55% in those without early mortality (p = 0.002, p = 0.02, p = 0.01). Early mortality was not significantly associated with age, HCT-CI score, second transplant, disease status at transplant, total dose of melphalan, volume overload/diuretic use, or post-transplant infection. In conclusion, we observed a very high rate of NRM with FluMel conditioning and PBSC grafts for haplo-SCT with PTCy. The pattern of toxicity was strongly associated with grade 2-4 CRS, AKI, and need for dialysis. These complications may be mediated by excessive inflammation in the context of allo-reactive donor T-cell over-activation. Consistent with this, multiple groups have shown that FluMel conditioning in haplo-SCT is safe when using bone marrow or T-cell depleted grafts. Based on our institutional experiences, we would discourage the use of FluMel as conditioning for haplo-SCT with PTCy with T-cell replete PBSC grafts. Alternative regimens or variations on melphalan-based regimens, such as fractionated melphalan dosing or inclusion of TBI may improve outcomes but further study and randomized controlled trials are needed. This study is limited in its retrospective design and sample size. Figure Disclosures DiPersio: WUGEN: Equity Ownership, Patents & Royalties, Research Funding; Karyopharm Therapeutics: Consultancy; Magenta Therapeutics: Equity Ownership; Celgene: Consultancy; Cellworks Group, Inc.: Membership on an entity's Board of Directors or advisory committees; NeoImmune Tech: Research Funding; Amphivena Therapeutics: Consultancy, Research Funding; Bioline Rx: Research Funding, Speakers Bureau; Macrogenics: Research Funding, Speakers Bureau; Incyte: Consultancy, Research Funding; RiverVest Venture Partners Arch Oncology: Consultancy, Membership on an entity's Board of Directors or advisory committees. Liesveld:Onconova: Other: Data safety monitoring board; Abbvie: Membership on an entity's Board of Directors or advisory committees.

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Severe Cytokine Release Syndrome Is Associated with Impaired Hematopoietic Recovery after CD19-Targeted CAR-T Cell Therapy

Blood ◽

10.1182/blood-2019-126922 ◽

2019 ◽

Vol 134 (Supplement_1) ◽

pp. 3229-3229 ◽

Cited By ~ 1

Author(s):

Krishna R. Juluri ◽

Alexandre V. Hirayama ◽

Erin Mullane ◽

Nancy Cleary ◽

Qian Vicky Wu ◽

...

Keyword(s):

T Cell ◽

Cell Therapy ◽

Board Member ◽

Ad Hoc ◽

Advisory Board ◽

T Cell Therapy ◽

Car T Cell ◽

Hematopoietic Recovery ◽

Car T Cell Therapy ◽

Car T

Background Chimeric antigen receptor therapy (CAR-T) directed against CD19 has demonstrated efficacy in patients with relapsed/refractory (R/R) B-cell malignancies. Delayed hematopoietic recovery with grade 3/4 neutropenia and thrombocytopenia, requiring extended growth factor administration or transfusions, has been observed in patients undergoing CAR-T cell therapy, although the factors influencing recovery are poorly understood. In this study, we performed multivariable analyses to identify factors associated with hematopoietic recovery in patients undergoing CD19 CAR-T cell therapy. Methods We retrospectively analyzed 125 patients with R/R acute lymphoblastic leukemia (ALL), non-Hodgkin lymphoma (NHL), and chronic lymphocytic leukemia (CLL), treated with CD19-targeted CAR-T cells on a phase 1/2 clinical trial in our institution (NCT01865617). Patients receiving more than one CAR-T infusion were excluded. Criteria for neutropenia, thrombocytopenia, and recovery were defined as per the Center for International Blood and Marrow Transplant Research (CIBMTR) reporting guidelines: neutropenia, absolute neutrophil count (ANC) ≤ 500/mm3; thrombocytopenia, platelet (Plt) count ≤ 20 x 109/L; neutrophil recovery, ANC > 0.5 x 109/L for three consecutive laboratory values obtained on different days irrespective of growth factor administration; platelet recovery, Plt > 20 x 109/L for three consecutive values obtained on different days in the absence of platelet transfusion for seven days. For competing risk analysis, an event was defined as having achieved ANC or Plt recovery, with the following considered as competing events: death, new cytotoxic therapy, relapse with marrow involvement in the absence of ANC or platelet recovery. Patients who never met the CIBMTR criteria for neutropenia of thrombocytopenia were considered as having recovered at time = 0. To identify factors associated with impaired hematopoietic recovery after CD19 CAR-T cell therapy, patient-, disease- and CAR-T cell therapy-related variables were included in a multivariable Fine and Gray model prior to variable selection using LASSO penalization (Table 2 footnote). Results We included 125 patients (ALL, n=44; CLL, n=37; NHL, n=44) with a median age of 55 (range, 20-76). Patients were heavily pre-treated with a median of 4 prior therapies (range, 1-10); 31% had undergone prior autologous or allogeneic hematopoietic cell transplantation (HCT). Median ANC and Plt prior to lymphodepletion were 2 x 109/L (range 0-23) and 112 x 109/L, range 3-425), respectively. Patient and treatment characteristics are summarized in Table 1. ANC and Plt recovery after CD19 CAR-T cell therapy were observed in 91% (ALL, 86%; CLL, 92%; NHL, 95%) and 86% (ALL, 86%; CLL, 86%; NHL, 84%) of patients, respectively. Median time to ANC recovery was 9 days and the probability of ANC recovery at day 28, 60, and 90 was 80% (95%CI, 73-87), 86% (95%CI, 80-92) and 89% (95%CI, 83-94), respectively. The probability of platelet recovery on the day of CAR-T cell infusion was 55% (95%CI, 46-64); rising to 74% (95%CI, 67-82), 83% (95%CI, 76-90), and 84% (95%CI, 77-90) at day 28, 60, and 90, respectively. A competing event was always observed in patients without ANC or Plt recovery. In multivariable analysis, higher pre-lymphodepletion Plt count (HR=1.08 per 25 x 109/L increase, p=0.006) and higher peak CD8+ CAR-T cells in blood (HR=1.47 per log10 cells/µL increase, p<0.001) were associated with faster ANC recovery. ALL diagnosis and higher cytokine release syndrome (CRS) grade were associated with slower ANC recovery (CLL vs ALL, HR=1.60, p=0.02; NHL vs ALL, HR=2.07, p=0.007). Higher CRS grade was also associated with slower Plt recovery (HR=0.67 per grade increase, p<0.001). Higher pre-lymphodepletion platelet count and higher peak CD8+ CAR-T cell in blood were associated with faster platelet recovery (HR=1.08 per 25 x 109/L increase, p=0.001; HR=1.41 per log10 cells/µL increase, p<0.001). Of note, lymphodepletion intensity did not seem to affect hematopoietic recovery. Table 2 summarizes the results of the multivariable analysis. Figure 1 shows ANC and Plt recovery by CRS grade. Conclusion We identified CRS grade as independently associated with impaired hematopoietic recovery after CD19 CAR-T cell therapy. Our findings suggest that the prevention of CRS may improve hematopoietic recovery after CD19 CAR-T cell therapy. Figure Disclosures Hirayama: DAVA Oncology: Honoraria. Maloney:Celgene,Kite Pharma: Honoraria, Research Funding; BioLine RX, Gilead,Genentech,Novartis: Honoraria; Juno Therapeutics: Honoraria, Patents & Royalties: patients pending , Research Funding; A2 Biotherapeutics: Honoraria, Other: Stock options . Turtle:Caribou Biosciences: Equity Ownership, Membership on an entity's Board of Directors or advisory committees; Nektar Therapeutics: Other: Ad hoc advisory board member, Research Funding; Allogene: Other: Ad hoc advisory board member; Novartis: Other: Ad hoc advisory board member; Juno Therapeutics: Patents & Royalties: Co-inventor with staff from Juno Therapeutics; pending, Research Funding; Precision Biosciences: Equity Ownership, Membership on an entity's Board of Directors or advisory committees; Eureka Therapeutics: Equity Ownership, Membership on an entity's Board of Directors or advisory committees; T-CURX: Membership on an entity's Board of Directors or advisory committees; Kite/Gilead: Other: Ad hoc advisory board member; Humanigen: Other: Ad hoc advisory board member.

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Initial Findings of the Phase 1 Trial of PBCAR0191, a CD19 Targeted Allogeneic CAR-T Cell Therapy

Blood ◽

10.1182/blood-2019-128203 ◽

2019 ◽

Vol 134 (Supplement_1) ◽

pp. 4107-4107 ◽

Cited By ~ 4

Author(s):

Caron A. Jacobson ◽

Alex F. Herrera ◽

Lihua E Budde ◽

Daniel J. DeAngelo ◽

Christopher Heery ◽

...

Keyword(s):

T Cell ◽

Peripheral Blood ◽

Cell Expansion ◽

Research Funding ◽

Lymphoblastic Leukemia ◽

Phase 1 ◽

Preliminary Evidence ◽

Cell Transplant ◽

Car T Cell ◽

Car T

Background: Adoptive engineered autologous cellular immunotherapy has had a significant impact on the lives of some patients with advanced hematologic malignancies. However, the use of these therapies on a larger proportion of patients has been limited by variability of the final cell product, feasibility concerns, cost, and toxicity. Off-the-shelf allogeneic (allo) products offer the opportunity to address some of these concerns. Allo products have their own theoretical limitations, including the potential for graft-versus-host disease (GvHD) causing additional toxicity and host-versus-graft rejection limiting efficacy. PBCAR0191, an anti-CD19 allogeneic CAR T cell, was designed to limit the risk of GvHD by specifically inserting a CD19 specific CAR into the TRAC (T cell receptor alpha constant) locus in cells harvested from healthy donors. Those cells are then expanded, a CD3 elimination step is performed, followed by another expansion, and then PBCAR0191 is vialed and frozen for shipment then thawing, dilution, and infusion at the treatment site. To reduce the risk of PBCAR0191 rejection and increase the chances of cell expansion, lymphodepletion prior to dosing is required. This phase 1 3+3 dose escalation study is designed to identify an optimal dose of PBCAR0191 for efficacy evaluation. Methods: In each of 3 dose levels (3 x 105, 1 x 106, and 3 x 106 CAR-T+ cells/kg), up to 6 patients may be enrolled in each of 2 cohorts (Non-Hodgkin Lymphoma (NHL) and Acute Lymphoblastic Leukemia (ALL)). Eligibility requirements include adequate organ function, confirmed diagnosis to fit one of the cohorts, evaluable disease, at least 2 prior standard treatment regimens, no immunodeficiencies, no CNS disease, no active infections or other major medical issues requiring intervention, and no active GvHD. Eligible patients may have received allogeneic stem cell transplant or another CAR-T therapy. Lymphodepletion was administered on day -5 to day -3 using fludarabine 30mg/m2/day and cyclophosphamide 500mg/m2/day. Cells were administered on day 0. Correlative serum and PBMC samples were taken, while patients remained on study, on days 0, 1, 3, 7, 10, 14, 28, 42, 60 and every 30 days until 180 and then every 90 days until day 360. Assessment of response compared to baseline was performed on day 14 (optional for NHL only), and days 28, 60, 90, 180, 270, and 360, until progression. Results: Three patients with advanced NHL were enrolled and treated in DL1 between April 25, 2019 and May 24, 2019. Two males (one MCL, one DLBCL) and 1 female (DLBCL) ages 34 - 64 (median 64) years were treated. Two screen failures occurred, both patients with ALL, due to non-compliance (1) and loss of CD19 surface expression (1). One patient enrolled post disease progression after treatment with Axicabtagene ciloleucel. No significant toxicity was observed, including no serious adverse events and no dose-limiting toxicities with all patients having a minimum follow-up of 28 days (median 60 days). Two of the three patients experienced objective tumor response by Lugano criteria, at day 14 and day 28, respectively. Both patients progressed due to new lesions (on day 28 and day 60, respectively). The third patient has not met the definition of response, but has had evidence of central necrosis, decreased tumor size, and decreased PET-avidity at day 28, in the context of post-infusion tumor site pain and mild CRS symptoms. Peripheral blood analysis for CAR-T expansion has identified preliminary evidence of cell expansion with a low absolute numbers quantified, likely due to the low dose level at which treatment was initiated. Peripheral blood serum analysis for IFN-gamma, IL-6, and IL-15 indicate preliminary evidence of cell expansion, though not definitive. Conclusions: Further enrollment of patients into DL2 is ongoing. Data from DL2 entered by early October will be included in a presentation in the meeting. Findings to date indicate preliminary evidence of short-lived cell-mediated anti-tumor effect and preliminary evidence of cell expansion in vivo, which will be evaluated more fully at DL2 and DL3. Disclosures Jacobson: Bayer: Consultancy, Other: Travel Expenses; Humanigen: Consultancy, Other: Travel Expenses; Kite, a Gilead Company: Consultancy, Honoraria, Other: Travel Expenses, Research Funding; Novartis: Consultancy, Honoraria, Other: Travel Expenses; Precision Biosciences: Consultancy, Other: Travel Expenses; Pfizer: Consultancy, Research Funding; Celgene: Consultancy, Other: Travel Expenses. Herrera:Adaptive Biotechnologies: Consultancy; Gilead Sciences: Consultancy, Research Funding; Seattle Genetics: Consultancy, Research Funding; AstraZeneca: Research Funding; Merck: Consultancy, Research Funding; Genentech, Inc.: Consultancy, Research Funding; Pharmacyclics: Research Funding; Immune Design: Research Funding; Kite Pharma: Consultancy, Research Funding; Bristol-Myers Squibb: Consultancy, Research Funding. Budde:F. Hoffmann-La Roche Ltd: Consultancy. DeAngelo:Amgen, Autolus, Celgene, Forty-seven, Incyte, Jazzs, Pfizer, Shire, Takeda: Consultancy; Novartis: Consultancy, Research Funding; Glycomimetics: Research Funding; Abbvie: Research Funding; Blueprint: Consultancy, Research Funding. Heery:Precision BioSciences: Employment. Stein:Amgen: Consultancy, Speakers Bureau; Stemline: Speakers Bureau; Celgene: Speakers Bureau. Jain:Kite/Gilead: Consultancy. Shah:Celgene/Juno: Honoraria; Kite/Gilead: Honoraria; Incyte: Research Funding; Jazz Pharmaceuticals: Research Funding; Pharmacyclics: Honoraria; Adaptive Biotechnologies: Honoraria; Spectrum/Astrotech: Honoraria; Novartis: Honoraria; AstraZeneca: Honoraria.

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Targeted Lymphocyte Depletion Prior to Reduced Intensity Allogeneic Stem Cell Transplantation: A Personalized Approach to Facilitate Engraftment.

Blood ◽

10.1182/blood.v114.22.865.865 ◽

2009 ◽

Vol 114 (22) ◽

pp. 865-865

Author(s):

Rachel B. Salit ◽

Seth Steinberg ◽

Daniel H. Fowler ◽

Jeanne Odom ◽

Kelly Bryant ◽

...

Keyword(s):

Stem Cell ◽

T Cell ◽

Whole Blood ◽

Graft Rejection ◽

Th2 Cells ◽

Mixed Chimerism ◽

Lymphocyte Depletion ◽

Gvhd Prophylaxis ◽

Personalized Approach ◽

Reduced Intensity

Abstract Abstract 865 Reduced intensity allogeneic stem cell transplantation (RIST) is associated with decreased transplant-related mortality (TRM), broadening the pool of patients who could potentially benefit from allogeneic cellular therapy. However, RIST is typically associated with higher rates of mixed chimerism and graft rejection compared to myeloablative conditioning. Data from clinical studies have shown that the number of therapies prior to transplant, which inversely correlates with host T-cell immunity, is a statistically important predictor of graft rejection and mixed chimerism. In order to compensate for variability in host immune status and facilitate early full-donor chimerism (>95%), we developed a strategy of targeted lymphocyte depletion (TLD) which uses repetitive cycles of disease-specific conventional-dose chemotherapy to provide both tumor cytoreduction and lymphocyte depletion prior to RIST. The number of TLD cycles (0-3 maximum) was based on reaching a target CD4+ count <100 cells/μl; patients with higher pre-TLD CD4+ count required more cycles. We employed the TLD approach in 111 patients (mean age = 49 years, (19-71) with advanced hematologic malignancies. Median CD3+, CD4+, and CD8+counts at enrollment were: 673 cells/μl (5-3953), 286 cells/μl (5-3888), and 277 cells/μl (1-1763) respectively. Following TLD chemotherapy, median CD3+, CD4+, and CD8+ counts were: 164 cells/μl (1-1496), 82 cells/μl (0-508), and 52 cells/μl (1-1195) respectively. All patients then received an identical reduced intensity conditioning regimen (fludarabine/cyclophosphamide) followed by HLA-matched sibling peripheral blood stem cell allografts. All patients received cyclosporine as graft versus host disease (GVHD) prophylaxis (1) alone, (2) with methotrexate, (3) with TH2 cells, (4) with sirolimus or (5) with TH2 cells and sirolimus. Immediately prior to stem cell infusion (Day 0) median host CD3+, CD4+, and CD8+ counts were 4 cells/μl (0-69), 3 cells/μl (0-65) , and 1 cell/μl (0-44) respectively. 109 evaluable patients demonstrated 100% engraftment; there were no graft failures. At Day +14, median lymphocyte chimerism was 99% and median myeloid and whole blood chimerism were 100%. Patients were able to maintain chimerism as evidenced by median 100% chimerism in the myeloid, lymphoid and whole blood compartments at Day +28 and median 100% whole blood chimerism at Day +100. Full donor lymphocyte chimerism at Day +14 was associated with lower post-TLD CD4+ counts (p=0.012) and Day 0 CD3+, CD4+, and CD8+ counts (p<0.0005). Full donor myeloid chimerism at Day+14 and Day+28 was associated with lower Day 0 CD3+, CD4+, CD8+ counts (p<0.05). Full donor whole blood chimerism at Day +14, Day +28 and Day+100 was associated with lower Day 0 CD3+, CD4+, and CD8+ counts (p<0.05). The CD3+ and CD34+ dose contained in the allograft was associated with Day +14 lymphoid chimerism (p=0.04) and with Day +28 myeloid chimerism (p=0.03) respectively. CMV status was associated with both lymphoid and whole blood chimerism at Day +14 (p<0.05). Only lymphoid chimerism at Day+28 was associated with GVHD prophylaxis regimen (p<0.05). Patients with acute GVHD II-IV had significantly lower CD4+ counts post-TLD (p=0.01). Patients with acute GVHD III-IV had significantly lower CD4+ and CD3+ counts at Day 0 (p<0.05). These data demonstrate the tremendous variability in pre-transplant host T-cell numbers. By using the strategy of TLD, we were able to compensate for this variability while achieving levels of T-cell depletion comparable to myeloablative conditioning. We conclude that TLD provides a personalized approach to pre-transplant host immune status resulting in absence of graft rejection and rapid and full donor chimerism following RIST. Disclosures: No relevant conflicts of interest to declare.

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