ALBERT

Description: Introduction: Blinatumomab is a bispecific, CD19-directed CD3 T-cell engager (BiTE®) that activates endogenous cytotoxic T cells to kill target B cells and is FDA-approved for the treatment of relapsed or refractory (R/R) B-cell precursor acute lymphoblastic leukemia (B-ALL). Subgroup analyses of pivotal trials revealed lower response rates and higher risk of cytokine release syndrome (CRS) in blinatumomab recipients with high pre-treatment tumor (B-ALL) burden. It has therefore been hypothesized that cytoreduction prior to blinatumomab initiation may improve response and reduce risk of severe CRS in patients (pts) with high baseline B-ALL burden. We therefore sought to describe pt and disease characteristics at diagnosis, patterns of pre-blinatumomab cytoreduction, and treatment outcomes in pts with high burden of R/R B-ALL treated with blinatumomab at our institution. Methods: We retrospectively reviewed medical records of adult (≥ 18 years-old) pts with morphologic R/R B-cell ALL (i.e. ≥5% BM blasts and/or radiographically evident EM disease) treated with blinatumomab at Memorial Sloan Kettering Cancer Center (MSKCC) between January 2011 and March 2019 and characterized pts with ≥ 50% bone marrow (BM) blasts by morphology or ≥ 15,000 peripheral blood blasts/µL as having "high-burden" B-ALL. CRS and neurologic toxicity (NTX) were graded per Common Terminology Criteria for Adverse Events v5.0. Objectives included describing cytoreductive therapy given pre-blinatumomab and determining rates of NTX and CRS (any grade and grade ≥3) and morphologic complete response (CR) following 1-2 cycles of blinatumomab. Results: We identified 14 pts with high-burden R/R B-ALL prior to blinatumomab. These pts had a median age of 52 years (range, 23 - 69 years) and median BM blasts of 73% (range, 52 - 〉95%, n=12 pts with evaluable BM). Of these 14 pts, 8 received cytoreductive therapy prior to blinatumomab initiation. Cytoreductive regimens included dexamethasone alone (n=4), cyclophosphamide + dexamethasone (n=2), dexamethasone and vincristine (n=1), or cyclophosphamide + vincristine + dexamethasone (n=1). One pt transitioned to hospice care prior to completing cycle 1 (C1) of blinatumomab and was considered non-evaluable for response. CR was achieved in 6 of the 13 evaluable pts, including 4 of 7 evaluable pts who received cytoreductive therapy and 2 of 6 pts who did not receive cytoreductive therapy. One pt achieved CR in BM but exhibited refractory extramedullary disease. CRS was observed during C1 of blinatumomab in 11/14 pts (grade 1, n=7; grade 2, n=3; grade 3, n=1). The pt with grade 3 CRS had received blinatumomab without cytoreductive therapy. In 4 pts, blinatumomab was temporarily discontinued for management of CRS. NTX of any grade occurred in 4/13 pts during C1, including 1 pt w/grade 3 NTX (depressed level of consciousness), and was reversible in all cases; the pt with grade 3 NTX had full resolution of symptoms following brief interruption of blinatumomab and administration of dexamethasone. Conclusions: Real-world clinical experience with blinatumomab in pts with high-burden B-ALL at a single institution suggested an efficacy and safety profile comparable to what has been reported in the overall population in clinical trials. Compared to published clinical trial experience, rates and severity of CRS following blinatumomab were similar and rates of NTX appeared slightly higher in this small series. Administration of cytoreductive therapy prior to blinatumomab for pts with high-burden B-ALL appears safe, with no additional toxicities. Larger studies will be required to assess whether pts with high-burden B-ALL treated (vs not treated) with cytoreductive therapy prior to blinatumomab exhibit significantly higher rates of CR. Disclosures King: Incyte: Other: Advisory Board; Genentech: Other: Advisory Board ; Astrazeneca: Other: Advisory board. Bolanos:Amgen Inc.: Employment. Velasco:Amgen Inc.: Employment. Tu:Amgen Inc.: Employment. Zaman:Amgen Inc.: Employment. Geyer:Dava Oncology: Honoraria; Amgen: Research Funding. Park:Allogene: Consultancy; Amgen: Consultancy; AstraZeneca: Consultancy; Autolus: Consultancy; GSK: Consultancy; Incyte: Consultancy; Kite Pharma: Consultancy; Novartis: Consultancy; Takeda: Consultancy.

Description: Abstract 3504 The only known curative therapy for patients with SCD is a matched family donor AlloSCT (Walters et al, NEJM, 1996). Complications after myeloablative AlloSCT are numerous and include death, graft versus host disease (GVHD), and infections, making reduced toxicity conditioning regimens more appealing. A major obstacle allowing most SCD patients to undergo SCT is the lack of an unaffected, HLA-matched identical sibling (Bhatia et al, BMT, 2008). Umbilical cord blood (UCB) has been proven to be an excellent alternate donor source that can safely reconstitute hematopoiesis after AlloSCT in pediatric recipients with non-malignant conditions (Cairo et al, BBMT, 2008). In this study, we report the results of a RTC regimen followed by an AlloSCT from matched family and unrelated UCB donors in selected patients with symptomatic SCD. Between August 27, 2004 and March 2, 2010, 18 patients (14M:2F) with symptomatic SCD (HbSS=10, HbSC=4, HbSßThal=4) underwent an AlloSCT. Indications for SCT included: ACS (n=8), CVA (n=2), multiple VOC (n=9), splenic sequestration (n=6) and retinopathy (n=1). Conditioning was Bu (4mg/kg × 4d 〈 4 yrs and 12.8mg/kg × 4d 〉 4 yrs), Flu (30mg/m2 × 6d), and Alemtuzumab (2mg/m2 × 1d, 6mg/m2 × 2d, and 20mg/m2 × 2d). Median age was 6.29 yrs(1.3–19.2). Median follow-up was 26 months. Donor sources: 8-6/6 HLA-matched sibling bone marrow (BM), 2–6/6 sibling UCB, 1–6/6, 4–5/6 and 3–4/6 unrelated UCB. Donors were HbAA (n=13), HbAC (n=1), HbAS(n=3), or ßThal trait (n=1). Sibling BM recipients received a median total nucleated cell (TNC) dose/kg of 7.16 × 108 (range 2.27–11.31) and a median CD34 cell dose/kg of 5.38 × 106 (range 1.50–6.83). Recipients of related or unrelated UCB received a median TNC dose/kg of 4.35 × 107 (range 3.40–9.10) and a median CD34 cell dose/kg of 2.21 × 105 (range 0.60–7.94). All received tacrolimus and mycophenolate mofetil as GVHD prophylaxis (Bhatia/Cairo et al, BBMT, 2009) and phenytoin or keppra as seizure prophylaxis for 180 days post SCT. Patients receiving sibling donor AlloSCT had a median time to neutrophil engraftment of 16 days (range 13–41). Among evaluable unrelated UCBT recipients, median time to neutrophil engraftment was 34 days (range 27–47). Four patients (all unrelated UCBT) experienced primary graft failure at day +60 post-SCT secondary to CMV (n=2), adenovirus, and low Bu Css levels with early withdrawal of MMF. Patients with sibling donors had a median time to platelet engraftment of 26 days (range 17–75). Of evaluable unrelated UCB recipients, median time to platelet engraftment was 54 days (range 43–70). Patients achieved mean whole blood donor chimerism of 71.0, 79.6, 85.7, 92.9, 90.7% and 93.2% at days 30, 60, 100, 180, 365 and 730 post-transplant, respectively. Mean erythroid (CD71) donor chimerism at these time points was 78.1, 81.1, 86.6, 90.5, 87.9% and 94.0%, respectively. Patients with non-sickle cell trait donors had median HbS levels of 0% at 1 yr (n=8) and 2 yrs (n=3) post-SCT; those with sickle cell trait donors had median HbS levels of 38.3% at 1 yr (n=3) and 39% at 2yrs (n=3) post-SCT. Among evaluable patients, the Kaplan-Meier probability of grade II-IV acute GVHD is 33.3% and of chronic GVHD is 8.3%. Among the ten donor-recipient pairs in which at least one member of the pair had CMV positivity, four experienced CMV reactivation on days +13, +26, +30 and +32 (BM: n=2, unrelated UCB: n=2). Of the four patients with primary graft failure (all unrelated UCBT recipients), one resumed chronic transfusions, two died of complications from disseminated CMV and adenoviral infections, and one received a second myeloablative SCT 1 yr after initial SCT and died of fungal sepsis. Among all patients, the Kaplan-Meier probability of OS is 81.8% (100% with sibling donors, 62.5% with UCB donors) and of EFS is 77.8% (100% with sibling donors, 50% with UCB donors) with none of these patients showing any evidence of SCD symptomatology post-SCT. The longest follow-up is 2134 days. In summary, we report the largest experience of RTC and matched family AlloSCT in selected children with symptomatic SCD with persistent long-term donor chimerism and absence of SCD symptoms or progression of disease. However, with the high incidence of viral infections and toxic deaths following unrelated UCBT, it is too premature to extend this treatment option to those SCD patients lacking a sibling donor. Disclosures: No relevant conflicts of interest to declare.

Description: Introduction: Asparaginase (ASP) has demonstrated a survival benefit in pediatric patients (pts) with acute lymphoblastic leukemia (ALL) and is now part of standard-of-care frontline treatment. As a result, asparaginase preparations have been incorporated into the treatment of adult ALL to improve outcomes. Pegaspargase (PEG-ASP), a modified version of asparaginase with prolonged asparagine depletion, appears to be safe in adults up to age 40 (Stock, et al., Blood, 2019), but is associated with a unique spectrum of toxicities, the risks of which appear to increase with age. Therefore, the safety of PEG-ASP remains a significant concern in older adults w/ ALL. Methods: We conducted a single center retrospective chart review of pts age ≥40 years who received PEG-ASP as part of frontline induction/consolidation or reinduction, between March 2008 and June 2018 at Memorial Sloan Kettering Cancer Center. The primary objective was to evaluate the tolerability and toxicity of PEG-ASP based on the incidence and severity of ASP-related toxicities (hypersensitivity reactions, hypertriglyceridemia, hyperbilirubinemia, transaminitis, pancreatitis, hypofibrinogenemia, etc) according to the Common Terminology Criteria for Adverse Events, version 4.03. Laboratory values recorded were either the peak or the nadir, the more appropriate for toxicity assessment, within a 4-week period following PEG-ASP administration. Secondary objectives were to determine the total number of doses of PEG-ASP administered in comparison to the number of doses intended, and to characterize the rationale for PEG-ASP discontinuation when applicable. Fisher's exact test was used to compare the incidence of PEG-ASP toxicities with respect to pt and treatment characteristics (regimen, age, BMI, gender, Philadelphia chromosome positive (Ph+) vs. Ph-, presence of extramedullary disease, PEG-ASP dose). P values were not adjusted for multiple comparisons. Results: We identified 60 pts with ALL (40 B-ALL and 20 T-ALL) who received at least one dose of PEG-ASP. Nine pts were Ph+. The median pt age at initiation of the treatment was 53, (range, 40 to 80), and 19 pts had a BMI ≥30 kg/m2. Forty-four pts received treatment for newly diagnosed ALL, and 16 pts for relapsed disease. Table 1 lists pt baseline characteristics. Among the 44 pts with newly diagnosed ALL, 27 pts received PEG-ASP as part of pediatric or pediatric-inspired regimens at doses of 2000 - 2500 units/m2, and 1 pt received a modified dose of 1000 units/m2 due to age. The remaining 16 pts received PEG-ASP at doses of 1000 - 2000 units/m2 for consolidation, per established adult regimens (ALL-2 and L-20; Lamanna, et al., Cancer, 2013). Grade 3/4 ASP-related toxicities with a 〉10% incidence included: hyperbilirubinemia, transaminitis, hypoalbuminemia, hyperglycemia, hypofibrinogenemia, and hypertriglyceridemia. Frontline treatment regimens in which PEG-ASP was used in consolidation cycles only (ALL-2, L-20) were associated w/ a lower incidence of hyperbilirubinemia (p=0.009) and hypertriglyceridemia (p

Description: Abstract 36 Introduction: Despite dramatic improvements in cure rates for pediatric ALL and AML, the prognosis remains poor for pediatric patients with ALL or AML in third complete remission (CR3) or with relapsed or refractory disease (10-20% EFS). Single-agent clofarabine has demonstrated activity in CAYA with relapsed or refractory ALL and AML (Jeha et al., Blood, 2004, JCO, 2006 and JCO, 2009). Clofarabine is a potent inhibitor of DNA polymerase and ribonucleotide reductase; biochemical and clinical studies suggest synergy with cytarabine (Faderl et al., Blood 2005). Clofarabine in combination with cytarabine has been studied in adults with AML and MDS and results in greater rates of CR than clofarabine alone (Faderl et al., Blood, 2006 and Blood, 2008). The combination of clofarabine and cytarabine in CAYA with relapsed acute leukemia appears to be safe and well-tolerated (Cooper et al., ASH, 2009). Objectives: To determine the maximum tolerated dose (MTD) of clofarabine in combination with cytarabine and TBI followed by AlloSCT and to assess the safety, progression-free survival (PFS) and overall survival (OS) associated with this regimen in CAYA with poor-risk acute leukemia. Methods: We instituted a multi-center phase I/II study of a novel conditioning regimen consisting of clofarabine, cytarabine and TBI prior to AlloSCT in CAYA with ALL or AML in CR3, relapse, or induction failure (IF). Herein we report results from the phase I portion of the study. Eligible patients received 5 days (day-9 to day-5) of clofarabine (dose escalation with 40 mg/m2 [n=3], 46 mg/m2 [n=3], 52 mg/m2 [n=6]) and sequential cytarabine 1000 mg/m2 (day-10 to day-5) and TBI (1200cGy) followed by AlloSCT from matched related or unrelated donors. Unrelated donor AlloSCT recipients also received R-ATG 2 mg/kg (day-4 to -2). GVHD prophylaxis consisted of tacrolimus and MMF as we have recently described (Bhatia/Cairo et al., BBMT, 2009). Probabilities of engraftment, acute and chronic GVHD, PFS and OS were computed using the Kaplan-Meier method. Results: Twelve patients enrolled, median age 11 years (range 5–18), 10/2 M/F, 9 ALL (6 CR3, 2 refractory relapse, 1 CR2 with history of IF), 3 AML (2 primary IF, 1 treatment-related AML in CR3), 6 with history of IF, 6 related donors (5 bone marrow [BM], 1 PBSCs), 6 unrelated donors (3 BM, 2 umbilical cord blood [UCB], 1 PBSCs). HLA matching was 5/6 (n=4) or 6/6 (n=4) at HLA-A, B and DRB1 for related donors and unrelated UCB donors and 9/10 (n=1) or 10/10 (n=3) at HLA-A, B, C, DRB1 and DQB1 for unrelated BM or PBSC donors. Median total nucleated cell dose (TNC) was 4.76×108/kg (2.30-14.56) and CD34 dose 5.04×106/kg (2.41-10.10) for patients receiving BM or PBSCs and 4.78×107/kg (4.00-5.55) and 4.04×105/kg (1.41-6.66), respectively, for patients receiving UCB grafts. An MTD of clofarabine was not exceeded at 52mg/m2/dose. No serious adverse events related to clofarabine were observed. One patient developed grade III hearing loss in the setting of atypical PRES, unlikely related to clofarabine, with normal cochlear function and abnormal auditory brainstem response. All engrafted neutrophils at median day 14 (12-29) and 90% of evaluable patients engrafted platelets at median day 36 (16-97). All achieved 100% whole blood donor chimerism by day +30. Day 100 transplant related mortality is 0%. The probability of grade II-IV acute GVHD was 43% (CI95: 13–71%); no patients developed chronic GVHD. Two patients died days +137 and +182 from multi-organ failure in the setting of infection and acute GVHD. Two experienced progressive disease on days +87 and +126 and received further therapy off study; one remains alive and stable. Eight are alive in continuous CR at a median of 209 days (40-770). Probabilities of PFS and OS are 53.3% (CI95: 18–80%) and 61.0% (CI95: 20–86%), respectively. Conclusions: Myeloablative conditioning with clofarabine, cytarabine and TBI followed by AlloSCT from related or unrelated donors is well tolerated in CAYA with poor-risk ALL and AML. Clofarabine 52 mg/m2/day × 5 days in combination with cytarabine and TBI can safely be used in the phase II study. Preliminary results from the phase I cohort are encouraging with respect to the risk of early relapse, despite poor-risk underlying disease. Efficacy data and measurements of change in minimal residual disease in the phase II study will provide a broader experience at the MTD to assess the role of this conditioning regimen in CAYA with poor-risk acute leukemia. Disclosures: Talano: Genzyme: Membership on an entity's Board of Directors or advisory committees. Cairo:Genzyme: Research Funding, Speakers Bureau.

Description: The CD3/CD19-targeted bispecific T-cell engager blinatumomab (BLIN) is active in pts w/ relapsed/refractory B-ALL or persistent minimal residual disease. Notable toxicities include cytokine release syndrome (CRS), a constellation of symptoms related to brisk systemic inflammatory response, and a spectrum of neurologic toxicities (NTX). BLIN prescribing information provides basic CRS/NTX management guidance, but limited reports describe "real-world" toxicity management strategies (TMS) and outcomes. We further previously reported association between higher baseline and peak levels of acute phase reactants (APR; C-reactive protein [CRP]/ferritin), time to APR peak, and incidence of CRS/NTX post-BLIN (King et al. ASH Annual Meeting, 2017). While CRS is also mediated in part by IL-6, routine monitoring of IL-6 levels during BLIN is not currently standard. As such, we sought to determine rates/severity of CRS/NTX at our institution, efficacy of TMS, and utility of APR/IL-6 in predicting CRS/NTX post-BLIN. We reviewed electronic medical records of pts ≥ 18 years (yrs) old w/ previously treated B-ALL receiving BLIN between 1/1/2011 and 3/31/19 at Memorial Sloan Kettering Cancer Center (MSK). NTX was classified/graded w/ CTCAEv5.0 (Common Terminology Criteria for Adverse Events). CRS was graded per CTCAEv5.0 and American Society for Transplantation and Cellular Therapy (ASTCT) criteria. The primary objective was to characterize rates/clinical features of CRS/NTX. Secondary objectives included assessing the nature/efficacy of TMS, and association of APR/IL-6 levels w/ CRS. Maximal (max) fold increase in APR/IL-6 was measured from pre-BLIN baseline to peak value during BLIN cycle 1 (C1). APR/IL-6 levels/fold changes were compared between groups using the Wilcoxon-Mann-Whitney test w/o adjustment for multiple comparisons. 59 pts were identified, including 31 male pts (52%). Median age at start of BLIN was 57 yrs (range, 20-76). Median number of prior therapies was 1, including 8 pts w/ previous allogeneic hematopoietic cell transplant (alloHCT) and 5 w/ prior chimeric antigen receptor T-cell therapy (CAR-T). No pt had baseline organ dysfunction or central nervous system (CNS) disease. All pts were admitted for initiation of BLIN C1. BLIN was started at 9 mcg/day IVCI w/ escalation to 28 mcg/day IVCI on day 8 (per recommended dosing for R/R ALL) in 52 pts and at 28 mcg/day IVCI in 7 pts for MRD (per Gökbuget et al., Blood, 2018). During BLIN C1, 34/59 pts experienced CRS (57%), w/ max grade (G) 1 (n=24), G2 (n=9) or G3 (n=1). CTCAEv5.0/ASTCT grading was concordant in all cases. Eight of 34 (23%) were managed w/ brief interruption of blinatumomab (BIB) for G1 (n=3) and G2 (n=5) CRS. Median duration of BIB was 39 hours (h) (range, 21-91h). Three pts had concomitant NTX and received brief courses of dexamethasone (DEX, daily dose of 24 mg). One pt w/ grade 2 CRS received tocilizumab for hypotension suboptimally responsive to fluid boluses (FB) w/ IL-6 level = 25754 pg/mL. Remaining pts w/ BIB (5/8) received FBs for hypotension. One pt permanently discontinued BLIN during C1 due to rapidly progressive B-ALL. All pts managed w/ BIB were successfully re-challenged w/ BLIN and finished C1 w/o recurrence of CRS. Of the 25/34 (74%) pts w/ CRS not managed w/ BIB, 5 received FBs, w/ 1 pt receiving a FB and a single dose of DEX. Five pts developed recurrent CRS (≥24 hours after resolution); 4/5 recurrences occurred in pts not managed w/ BIB. NTX, excluding isolated headache, was observed in 8/59 pts (14%) during BLIN C1 (Table 1) w/ max G1 (n=4), G2 (n=3), or G3 (n=1). Four pts w/ NTX were managed w/ BIB and a brief course DEX; 3/4 had concomitant CRS. Median time to onset of CRS and NTX were 1 day (d) (range 0-15) and 2 d (range 0-10), respectively. Non-significant trend toward higher peak IL-6 was noted in pts w/ G1 vs. G0 CRS (p=0.07; Fig 1A, note log scale); median peak levels of CRP were higher in pts w/ G1 vs G0 CRS (p=0.01, Fig 1B); median peak ferritin levels were higher in pts w/ G2 vs. G0 CRS (p=0.01, Fig 1C). While CRS was common during C1 of BLIN, supportive management was sufficient in most pts; BIB was an effective strategy and allowed successful BLIN re-challenge. The incidence of ≥G2 NTX was low and all cases of NTX were reversible w/ supportive care or BIB ± DEX. Peak APR levels correlated w/ CRS severity. Authors noted concordance of CRS grading between CTCAE and ASTCT, suggesting the feasibility of a single, BITE-specific grading system. Disclosures King: Astrazeneca: Other: Advisory board; Genentech: Other: Advisory Board ; Incyte: Other: Advisory Board. Park:Amgen: Consultancy; AstraZeneca: Consultancy; Autolus: Consultancy; GSK: Consultancy; Incyte: Consultancy; Kite Pharma: Consultancy; Novartis: Consultancy; Takeda: Consultancy; Allogene: Consultancy. Geyer:Amgen: Research Funding; Dava Oncology: Honoraria.

Description: Background: The treatment indications for venetoclax in CLL are broadening quickly. While the initial approval was for relapsed patients with del 17p (Stilgenbauer S, et al. JCO 2018), it has subsequently been extended to all patients (Seymour J, et al. NEJM 2018, Fischer K, et al. NEJM 2019). The duration of therapy with each approval has evolved as well, from continuing therapy until progression/toxicity to 1 year in front-line CLL. The limited durations of therapy were applied to all patients based on trial design and were not dependent on response to treatment. Undetectable minimal residual disease (U-MRD) with venetoclax is associated with improved progression-free survival (PFS), both as a single agent and in combination with rituximab (Stilgenbauer S, et al. JCO 2018, Seymour J, et al. NEJM 2018). Early phase data suggest that patients who discontinue venetoclax after achieving MRD negativity can be monitored off therapy and successfully retreated upon relapse (Seymour J, et al, Lancet Onc 2017). However, patients who discontinue therapy with persistent residual disease have a higher incidence of relapse (Kater A, et al. JCO 2019). Together, these data suggest that the duration of venetoclax therapy should be individualized, based on the depth of response one achieves and not a fixed duration schedule. Therefore, we propose a prospective clinical trial, utilizing MRD assessment with a next generation sequencing (clonoSEQ®) assay to guide clinical decision making in patients with CLL receiving venetoclax-based regimens. Methods: This is a multicenter, phase II clinical stopping trial for 80 venetoclax-treated CLL patients. The clonoSEQ® assay is used to assess MRD, and patients who achieve U-MRD (defined as

Description: Introduction: Signaling through JAK1 and/or JAK2 is common among tumor and non-tumor cells within peripheral and cutaneous T cell lymphomas (PTCL and CTCL). We conducted a phase II study of the JAK1/2 inhibitor, ruxolitinib, in patients (pts) with PTCL and CTCL and assessed the predictive value of genetic, immunohistochemical (IHC) and multiparametric immunofluorescence (mIF) biomarkers of JAK/STAT pathway activation for ruxolitinib response. Methods: This is an investigator-initiated multi-center phase II study for pts with relapsed or refractory (RR) PTCL or CTCL following at least 1 systemic therapy. Biopsies from each patient were subjected to next-generation sequencing for JAK1, JAK2, STAT3, STAT5 and other relevant genes along with IHC assessment for phosphorylated STAT3 (pSTAT3). Pts enrolled into biomarker-defined cohorts: 1) activating JAK and/or STAT mutations (allele frequency of 0.1 or greater); 2) no JAK/STAT mutation but ≥ 30% pSTAT3 expression among tumor cells by IHC; or 3) neither. Pts received treatment with ruxolitinib 20 mg BID until progression and were assessed for response after cycles 2, 5 and every three cycles thereafter. Tissue samples collected at baseline, on-treatment, and at progression were collected and assessed by mIF (Vectra platform, HALO analysis) using markers specific for lymphoma subtype, macrophage activation, JAK/STAT and PI3 kinase signaling. Results: The study completed enrollment with 53 pts, including 18 in cohort 1, 14 in cohort 2, and 21 in cohort 3. Cohort 3 includes 10 pts for whom JAK/STAT characterization is pending. Disease histologies per cohort are detailed in table 1. Treatment-related serious adverse events included HSV-1 stomatitis (n=1), spontaneous bacterial peritonitis (n=1), febrile neutropenia (n=3), and herpes zoster (n=1). Additional grade 3 or 4 drug-related adverse events affecting 〉1 pt included neutropenia (n=13), anemia (n=8), thrombocytopenia (n=5), and lymphopenia (n=3). Among the 53 pts, 4 have not yet reached first response assessment and 1 withdrew consent following only 1 week of treatment; therefore 48 are evaluable for response. Among 48 pts, there were 3 (6%) complete responses, 8 (17%) partial responses, and 6 (12.5%) with cytopenia improvement and disease stabilization lasting more than 6 months (SD〉6 mo). Overall response rate (ORR) was 23% and overall clinical benefit rate (CBR) (ORR plus SD〉6 mo) was 35%. Median duration of response was 7.3 months (range 1.3-26.1 months). ORRs in cohorts 1, 2 and 3 were 28%, 31%, and 12% (cohorts 1&2 vs 3, p=0.28). CBRs in cohorts 1, 2 and 3 were 44%, 46%, and 18% (cohorts 1&2 vs. 3, p=0.07) (table 2). More frequent responses were observed in the following histologies: angioimmunoblastic T cell lymphoma, peripheral T cell lymphoma with T-follicular helper phenotype, T-cell prolymphocytic leukemia, and large granular lymphocyte leukemia (table 3). Nine pre-treatment biopsies were analyzed by mIF from 4 ruxolitinib responders and 5 non-responders. The most notable finding was that responders to ruxolitinib had markedly lower pS6 expression within tumor cells of pre-treatment biopsies (mean pS6 expression 9.03 +/- 4.8 vs 48.19 +/- 6.6 for nonresponders; p=0.0027). In a patient with prolonged CR on ruxolitinib, progression biopsy was characterized by a marked increase in tumor cell pS6 staining. Additional samples are being analyzed and updated results will be reported at the meeting. Conclusion: The JAK1/JAK2 inhibitor ruxolitinib is a well-tolerated and readily available therapy for pts with relapsed/refractory PTCL and CTCL. Among patients with IHC and/or genetic evidence of JAK/STAT activation, ruxolitinib has similar efficacy to approved agents for relapsed/refractory T-cell lymphoma. The association between pS6 expression and response to ruxolitinib suggests that active PI3K/mTOR signaling confers intrinsic and acquired resistance to ruxolitinib. Disclosures Moskowitz: ADC Therapeutics: Consultancy; Takeda Pharmaceuticals: Consultancy; Seattle Genetics: Consultancy, Honoraria, Research Funding; Bristol-Myers Squibb: Consultancy, Research Funding; Takeda Pharmaceuticals: Consultancy; Kyowa Hakko Kirin Pharma: Consultancy, Research Funding; Takeda Pharmaceuticals: Consultancy; Takeda Pharmaceuticals: Consultancy; Bristol-Myers Squibb: Consultancy, Research Funding; miRagen Therapeutics Inc: Consultancy, Research Funding; Seattle Genetics: Consultancy, Honoraria, Research Funding; Seattle Genetics: Consultancy, Honoraria, Research Funding; Erytech Pharma: Consultancy; Seattle Genetics: Consultancy, Honoraria, Research Funding; Merck: Research Funding; Takeda Pharmaceuticals: Consultancy; Merck: Research Funding; Kyowa Hakko Kirin Pharma: Consultancy, Research Funding; Kyowa Hakko Kirin Pharma: Consultancy, Research Funding; Bristol-Myers Squibb: Consultancy, Research Funding; Incyte: Research Funding; Merck: Research Funding; Takeda Pharmaceuticals: Consultancy; ADC Therapeutics: Consultancy; Merck: Research Funding; Seattle Genetics: Consultancy, Honoraria, Research Funding; miRagen Therapeutics Inc: Consultancy, Research Funding; miRagen Therapeutics Inc: Consultancy, Research Funding; Seattle Genetics: Consultancy, Honoraria, Research Funding; Merck: Research Funding; Seattle Genetics: Consultancy, Honoraria, Research Funding; Merck: Research Funding; miRagen Therapeutics Inc: Consultancy, Research Funding; Erytech Pharma: Consultancy; Erytech Pharma: Consultancy; Incyte: Research Funding; Takeda Pharmaceuticals: Consultancy; Kyowa Hakko Kirin Pharma: Consultancy, Research Funding; Kyowa Hakko Kirin Pharma: Consultancy, Research Funding; Takeda Pharmaceuticals: Consultancy; Seattle Genetics: Consultancy, Honoraria, Research Funding; Kyowa Hakko Kirin Pharma: Consultancy, Research Funding; Merck: Research Funding; Seattle Genetics: Consultancy, Honoraria, Research Funding; Merck: Research Funding; Merck: Research Funding; Cell Medica: Consultancy; Bristol-Myers Squibb: Consultancy, Research Funding; Bristol-Myers Squibb: Consultancy, Research Funding; Bristol-Myers Squibb: Consultancy, Research Funding; Bristol-Myers Squibb: Consultancy, Research Funding; miRagen Therapeutics Inc: Consultancy, Research Funding; Incyte: Research Funding; miRagen Therapeutics Inc: Consultancy, Research Funding; ADC Therapeutics: Consultancy; miRagen Therapeutics Inc: Consultancy, Research Funding; Incyte: Research Funding; Cell Medica: Consultancy; Merck: Research Funding; ADC Therapeutics: Consultancy; Cell Medica: Consultancy; Incyte: Research Funding; miRagen Therapeutics Inc: Consultancy, Research Funding; Erytech Pharma: Consultancy; Cell Medica: Consultancy; Cell Medica: Consultancy; miRagen Therapeutics Inc: Consultancy, Research Funding; Incyte: Research Funding; Erytech Pharma: Consultancy; Cell Medica: Consultancy; Takeda Pharmaceuticals: Consultancy; Cell Medica: Consultancy; Cell Medica: Consultancy; Bristol-Myers Squibb: Consultancy, Research Funding; Incyte: Research Funding; Incyte: Research Funding; Takeda Pharmaceuticals: Consultancy; Cell Medica: Consultancy; Takeda Pharmaceuticals: Consultancy; Takeda Pharmaceuticals: Consultancy; Cell Medica: Consultancy; Cell Medica: Consultancy; miRagen Therapeutics Inc: Consultancy, Research Funding; Cell Medica: Consultancy; Kyowa Hakko Kirin Pharma: Consultancy, Research Funding; Kyowa Hakko Kirin Pharma: Consultancy, Research Funding; miRagen Therapeutics Inc: Consultancy, Research Funding; Kyowa Hakko Kirin Pharma: Consultancy, Research Funding; Takeda Pharmaceuticals: Consultancy; Incyte: Research Funding; Seattle Genetics: Consultancy, Honoraria, Research Funding; Kyowa Hakko Kirin Pharma: Consultancy, Research Funding; Bristol-Myers Squibb: Consultancy, Research Funding; miRagen Therapeutics Inc: Consultancy, Research Funding; Erytech Pharma: Consultancy; Kyowa Hakko Kirin Pharma: Consultancy, Research Funding; Incyte: Research Funding; ADC Therapeutics: Consultancy; Kyowa Hakko Kirin Pharma: Consultancy, Research Funding; Cell Medica: Consultancy; Merck: Research Funding; ADC Therapeutics: Consultancy; Erytech Pharma: Consultancy; Erytech Pharma: Consultancy; Erytech Pharma: Consultancy; ADC Therapeutics: Consultancy; Incyte: Research Funding; Incyte: Research Funding; miRagen Therapeutics Inc: Consultancy, Research Funding; Seattle Genetics: Consultancy, Honoraria, Research Funding; ADC Therapeutics: Consultancy; Bristol-Myers Squibb: Consultancy, Research Funding; ADC Therapeutics: Consultancy; ADC Therapeutics: Consultancy; miRagen Therapeutics Inc: Consultancy, Research Funding; Incyte: Research Funding; Merck: Research Funding; Takeda Pharmaceuticals: Consultancy; Cell Medica: Consultancy; Kyowa Hakko Kirin Pharma: Consultancy, Research Funding; Merck: Research Funding; Incyte: Research Funding; Merck: Research Funding; Seattle Genetics: Consultancy, Honoraria, Research Funding; Incyte: Research Funding; Bristol-Myers Squibb: Consultancy, Research Funding; ADC Therapeutics: Consultancy; ADC Therapeutics: Consultancy; ADC Therapeutics: Consultancy; ADC Therapeutics: Consultancy; ADC Therapeutics: Consultancy; Erytech Pharma: Consultancy; Erytech Pharma: Consultancy; Erytech Pharma: Consultancy; Erytech Pharma: Consultancy; Bristol-Myers Squibb: Consultancy, Research Funding; Erytech Pharma: Consultancy; Erytech Pharma: Consultancy; Bristol-Myers Squibb: Consultancy, Research Funding; Seattle Genetics: Consultancy, Honoraria, Research Funding; Cell Medica: Consultancy; Kyowa Hakko Kirin Pharma: Consultancy, Research Funding; Merck: Research Funding; Takeda Pharmaceuticals: Consultancy; miRagen Therapeutics Inc: Consultancy, Research Funding; Seattle Genetics: Consultancy, Honoraria, Research Funding; Seattle Genetics: Consultancy, Honoraria, Research Funding; Kyowa Hakko Kirin Pharma: Consultancy, Research Funding; Bristol-Myers Squibb: Consultancy, Research Funding; Bristol-Myers Squibb: Consultancy, Research Funding. Jacobsen:Acerta: Consultancy; Novartis: Research Funding; Astra-Zeneca: Consultancy; F. Hoffmann-LaRoche: Research Funding; Merck: Consultancy, Research Funding; Takeda: Honoraria; Pharmacyclics: Research Funding. Ruan:Janssen: Consultancy, Honoraria; Pharmacyclics LLC, an AbbVie company: Research Funding; Kite: Consultancy; Juno: Consultancy; Celgene: Consultancy, Honoraria, Research Funding; AstraZeneca: Consultancy, Honoraria; Seattle Genetics: Consultancy, Honoraria, Research Funding. Geyer:Amgen: Research Funding; Dava Oncology: Honoraria. Noy:Medscape: Honoraria; Janssen: Consultancy; Prime Oncology: Honoraria; NIH: Research Funding; Pharamcyclics: Research Funding; Raphael Pharma: Research Funding. Straus:Elsevier (PracticeUpdate): Consultancy, Honoraria; Hope Funds for Cancer Research: Membership on an entity's Board of Directors or advisory committees; Seattle Genetics: Consultancy, Honoraria. Dogan:Roche: Consultancy, Research Funding; Corvus Pharmaceuticals: Consultancy; Seattle Genetics: Consultancy; Celgene: Consultancy; Novartis: Consultancy; Takeda: Consultancy. Weinstock:Celgene: Research Funding. Horwitz:Aileron: Research Funding; Corvus Pharmaceuticals: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Celgene: Consultancy, Research Funding; Seattle Genetics: Consultancy, Research Funding; Kura: Consultancy; Infinity/Verastem: Consultancy, Research Funding; Seattle Genetics: Consultancy, Research Funding; Aileron: Research Funding; Trillium: Research Funding; Kyowa Hakko Kirin: Consultancy; Corvus Pharmaceuticals: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Astex: Consultancy; Miragen: Consultancy; Affimed: Consultancy; ADCT Therapeutics: Research Funding; Forty-Seven: Research Funding; Portola: Consultancy; Miragen: Consultancy; Mundipharma: Consultancy; Miragen: Consultancy; Seattle Genetics: Consultancy, Research Funding; Millennium/Takeda: Consultancy, Research Funding; Innate Pharma: Consultancy; Affimed: Consultancy; ADCT Therapeutics: Research Funding; Millennium/Takeda: Consultancy, Research Funding; Millennium/Takeda: Consultancy, Research Funding; Infinity/Verastem: Consultancy, Research Funding; Kyowa Hakko Kirin: Consultancy; Trillium: Research Funding; Astex: Consultancy; Astex: Consultancy; Celgene: Consultancy, Research Funding; Infinity/Verastem: Consultancy, Research Funding; Infinity/Verastem: Consultancy, Research Funding; Kura: Consultancy; Kura: Consultancy; Kyowa Hakko Kirin: Consultancy; Trillium: Research Funding; Celgene: Consultancy, Research Funding; ADCT Therapeutics: Research Funding; Corvus Pharmaceuticals: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Astex: Consultancy; Aileron: Research Funding; Forty-Seven: Research Funding; Innate Pharma: Consultancy; Forty-Seven: Research Funding; Mundipharma: Consultancy; Celgene: Consultancy, Research Funding; Seattle Genetics: Consultancy, Research Funding; Portola: Consultancy; Kyowa Hakko Kirin: Consultancy; Millennium/Takeda: Consultancy, Research Funding; Trillium: Research Funding; Aileron: Research Funding; Kura: Consultancy; Miragen: Consultancy; Innate Pharma: Consultancy; Mundipharma: Consultancy; Mundipharma: Consultancy; ADCT Therapeutics: Research Funding; Corvus Pharmaceuticals: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Portola: Consultancy; Portola: Consultancy; Forty-Seven: Research Funding; Innate Pharma: Consultancy; Affimed: Consultancy; Affimed: Consultancy. OffLabel Disclosure: Off-label use of ruxolitinib for T-cell lymphoma will be discussed

Description: Introduction: Adults with (w/) B-cell acute lymphoblastic leukemia (B-ALL) exhibit high rates of complete response (CR) to induction chemotherapy, but relapse is common. Inotuzumab ozogamicin (IO), an antibody-drug conjugate targeting CD22, achieves high rates of CR in patients (pts) w/ relapsed/refractory (R/R) B-ALL and is FDA-approved for R/R B-ALL in adults. It remains unknown whether cytogenetic and molecular features associated w/ decreased response rate and poor prognosis following conventional chemotherapy are associated w/ response to IO. As such, we investigated the relationship between several high-risk genetic alterations and outcome following IO treatment in pts w/ R/R B-ALL. Methods: We reviewed electronic medical records of pts of all ages w/ R/R B-ALL or chronic myeloid leukemia in lymphoid blast phase (CML-LBP) receiving IO at Memorial Sloan Kettering Cancer Center (MSK) between January 2011 and April 2019. The primary objective was to assess whether recurrent cytogenetic or molecular features were associated w/ achievement of CR or CR w/ incomplete hematologic recovery (CRi), w/ or w/o measurable residual disease (MRD), and disease-free (DFS) and overall survival (OS) following IO. Secondary objectives included association of baseline clinical features, including central nervous system (CNS) or other extramedullary (EM) disease, w/ outcomes post-IO. MRD was defined as any unequivocal evidence of B-ALL detectable by RT-PCR (Ph+ ALL) or flow cytometry (FACS). Genomic alterations were defined by MSK IMPACT-Heme (Cheng, J Mol Diagn, 2015), FoundationOne Heme, or similar platforms. A set of selected high-risk (HR) features in Philadelphia chromosome-negative (Ph-) B-ALL was defined prior to the analysis (HR: mutations/loss of TP53, IKZF1/3, CDKN2A, CREBBP; activating RAS mutations; "Ph-like" profile). DFS and OS were computed using Kaplan-Meier methods and compared between groups using log-tank tests. Results: 32 pts (13F, 19M) w/ R/R B-ALL (n=31) or CML-LBP (n=1) treated w/ IO were identified. IO was given as monotherapy in 27 pts and w/ other systemic therapy in 5 pts (mini-hyper-CVD-like regimen, n=4; ponatinib, n=1). Median age at start of IO was 45 years (range 3-78). 10 pts had undergone prior allogeneic hematopoietic cell transplantation (alloHCT). Seven and 15 pts had a history of CNS disease or other EM involvement by B-ALL, respectively, including 3 and 6 pts immediately prior to IO, respectively. Pts received a median 3 lines of salvage prior to IO, including prior CD19-targeted immunotherapy (blinatumomab and/or CAR-T cells) in 24 pts(Table 1). Among 27 pts w/ Ph- B-ALL, 12 had the selected HR features (Table 2). Five pts had Ph+ ALL (n=4) or CML-LBP (n=1) and 5/5 harbored ABL1 kinase domain point mutations (4/5 w/ T315I mutation). 22 pts had at least one successful molecular profiling panel.29 patients had initial cytogenetic studies, of whom 28 patients had evaluable karyotypes. 23 pts had best response to IO of CR/CRi (MRD-, n=15; MRD+, n=8). 9 pts had no objective response to ≥1 cycle of IO. Of the 12 Ph- pts w/ selected HR mutations, 11 achieved CR/CRi. Notably, 6/6 pts w/ TP53 mutation/deletion and 5/5 pts w/ IKZF1/3 mutations (3/3 pts w/ both TP53 & IKZF mutations) achieved CR/CRi. Both pts w/ Ras mutations and 2/3 w/ Ph-like B-ALL achieved CR/CRi. 7/11 HR responders underwent alloHCT post-IO (3 had undergone pre-IO alloHCT). Pts w/ Ph- B-ALL w/ HR mutations demonstrated similar CR/CRi rate and OS to pts w/ Ph- B-ALL w/o defined HR mutations (Fig 1A-B). In contrast, only 1/5 pts w/ Ph+ ALL achieved CR/CRi (was MRD+) and 4/5 showed persistent B-ALL. OS was superior among pts w/ Ph- vs Ph+ B-ALL post-IO (8.0 vs 1.9 months, p=0.0068, Fig 1C). Among pts w/ EM disease immediately prior to IO, 3/6 achieved CR/CRi, including CR in 1 pt w/ a cardiac mass. Median DFS was 3.2 months vs. not reached following achievement of MRD+ vs MRD- CR, respectively (p=ns, Fig 1D). Conclusions: HR molecular features associated w/ poor response to chemotherapy were not associated w/ inferior response rate and overall prognosis following IO in this small series. Notably, pts w/ Ph+ ALL (all w/ ABL1 mutations) exhibited suboptimal response, possibly as pts received IO only in advanced disease states following TKI failure. This small report supports investigation of IO in frontline therapy for pts w/ B-ALL w/ HR mutations to spare unnecessary toxicities of chemotherapy and bridge successfully to alloHCT. Disclosures King: Genentech: Other: Advisory Board ; Astrazeneca: Other: Advisory board; Incyte: Other: Advisory Board. Park:Allogene: Consultancy; Amgen: Consultancy; AstraZeneca: Consultancy; Autolus: Consultancy; GSK: Consultancy; Incyte: Consultancy; Kite Pharma: Consultancy; Novartis: Consultancy; Takeda: Consultancy. Geyer:Dava Oncology: Honoraria; Amgen: Research Funding. OffLabel Disclosure: Inotuzumab ozogamicin is not FDA approved for pediatric patients with relapsed/refractory B-cell acute lymphoblastic leukemia.

Description: Adoptive transfer of T cells genetically modified to express chimeric antigen receptors (CARs) targeting CD19 has produced impressive results in treating patients with B-cell malignancies. Although these CAR-modified T cells target the same antigen, the designs of CARs vary as well as several key aspects of the clinical trials in which these CARs have been studied. It is unclear whether these differences have any impact on clinical outcome and treatment-related toxicities. Herein, we review clinical results reflecting the investigational use of CD19-targeted CAR T-cell therapeutics in patients with B-cell hematologic malignancies, in light of differences in CAR design and production, and outline the limitations inherent in comparing outcomes between studies.