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PURPOSE The development of highly effective targeted agents for chronic lymphocytic leukemia offers the potential for fixed-duration combinations that achieve deep remissions without cytotoxic chemotherapy. PATIENTS AND METHODS This phase II study tested a combination regimen of obinutuzumab, ibrutinib, and venetoclax for a total of 14 cycles in both patients with treatment-naïve (n = 25) and relapsed or refractory (n = 25) chronic lymphocytic leukemia to determine the response to therapy and safety. RESULTS The primary end point was the rate of complete remission with undetectable minimal residual disease by flow cytometry in both the blood and bone marrow 2 months after completion of treatment, which was 28% in both groups. The overall response rate at that time was 84% in treatment-naïve patients and 88% in relapsed or refractory patients. At that time, 67% of treatment-naïve patients and 50% of relapsed or refractory patients had undetectable minimal residual disease in both the blood and marrow. At a median follow-up of 24.2 months in treatment-naïve patients and 21.5 months in relapsed or refractory patients, the median progression-free and overall survival times were not yet reached, with only 1 patient experiencing progression and 1 death. Neutropenia and thrombocytopenia were the most frequent adverse events, followed by hypertension. Grade 3 or 4 neutropenia was experienced by 66% of patients, with more events in the relapsed or refractory cohort. There was only 1 episode of neutropenic fever. A favorable impact on both perceived and objective cognitive performance during treatment was observed. CONCLUSION The combination regimen of obinutuzumab, ibrutinib, and venetoclax offers time-limited treatment that results in deep remissions and is now being studied in phase III cooperative group trials.

7540 Background: Targeted agent combinations for chronic lymphocytic leukemia (CLL) have resulted in safe regimens with improved progression-free survival (PFS) compared to chemoimmunotherapy. The optimal regimen and long-term outcomes remain unknown. We conducted a phase 2 study of obinutuzumab (OBIN), ibrutinib (IBR), and venetoclax (VEN) in relapsed/refractory (RR) and treatment-naïve (TN) CLL patients (pts) and report extended follow up on two previously reported cohorts (RR, TN 1) and a new cohort of identically treated TN pts (TN 2). Methods: Pts with TN or RR (≥1 prior treatment) CLL requiring treatment were eligible. Treatment was given for 14 28-day cycles (C). OBIN was started C1, IBR C2, and VEN C3 with standard dose escalation. Response was assessed 2 months (mos) after C14 (EOT) by iwCLL 2008 criteria. Minimal residual disease (MRD) was measured by 10-color flow cytometry with a cutoff of < 1x10-4. The primary endpoint was complete remission (CR) with undetectable MRD (uMRD) in blood and bone marrow at EOT. A sample size of 25 pts per cohort achieves 90% power to test the null hypothesis of 10% against 30% with 1-sided α of 10%. The Kaplan-Meier method was used to estimate PFS and overall survival (OS). Results: 75 pts were treated in 3 cohorts (Table). Data are as of 1/3/2022. In the TN 2 cohort, the overall response rate (ORR) at EOT was 96% (95% CI: 80-100) and CR with uMRD was 20% (95% CI: 7-41). The ORR for TN 1 and TN 2 combined was 90% (95% CI: 78-97) and CR with uMRD was 24% (95% CI: 13-38). Median follow up was 56 (0-65), 57 (7-63), and 30 (24-35) mos, respectively, for RR, TN 1, and TN 2. There were 3 deaths (RR = 1, TN 1 = 1, TN 2 = 1) and 6 disease progressions (RR = 4, TN 1 = 2, TN 2 = 0). Estimated 48-month PFS for TN 1 and RR cohorts were both 96% (95% CI: 72-99) and OS was 85% (95% CI: 60-95) and 100%, respectively. The estimated 24-month PFS and OS for TN 2 were both 96% (95% CI: 75-99). The most frequent adverse events were neutropenia (95%, 73% grade ≥3), leukopenia (95%, 45% grade ≥3), lymphopenia (93%, 40% grade ≥3), and thrombocytopenia (91%, 28% grade ≥3). The only grade ≥3 non-hematologic toxicity occurring at ≥20% was hypertension (85%, 39% grade ≥3). Atrial fibrillation occurred in 11% of pts. Conclusions: At extended follow-up, remissions remain durable after fixed duration OBIN, IBR, and VEN. The efficacy and acceptable safety justify further study and are being compared to IBR and OBIN in 2 phase 3 US cooperative group trials. Clinical trial information: NCT02427451. [Table: see text]

7027 Background: TP-0903 is a multi-kinase inhibitor designed to target AXL, a receptor tyrosine kinase, and also inhibits cell cycle regulators such as Chk1/2 and other AML associated kinases. TP-0903 has shown prior anti-tumor activity at a safe dose in solid tumors. In pre-clinical AML studies, TP-0903 shows potent cytotoxicity in TP53 mutant ( TP53m) AML cell lines, an adverse prognostic genomic sub-group of AML. TP-0903 also had synergistic activity with decitabine (dec) in TP53m AML and prolonged survival in xenograft and genetically engineered mouse models. We report here on the initial safety and clinical results from the Leukemia and Lymphoma Society’s ongoing Beat AML phase 1b/2 (Ph1b/2) trial of TP-0903 in combination with dec (ClinicalTrials.gov NCT03013998). Methods: Newly diagnosed AML pts ≥60 years with TP53m and/or complex karyotype (≥3 abnormalities) were selected for a Ph1b/2 dose escalation study of TP-0903 combined with dec. Seven Ph1b pts were given TP-0903 every 28-day cycle from days 1-21 (Dose level (DL) 1 = 37 mg/day) and dec IV days 1-10 (20 mg/m2). A standard 3+3 design was used to evaluate the safety and tolerability. Nine additional patients enrolled onto Ph2 at DL1, but further assessments of safety, pharmacokinetics (PK) and correlative data was used to update the final recommended Ph2 dose (RP2D) of TP-0903 to DL-1 (25 mg/day) with dec. Results: At data cutoff (10Jan2022), 16 total pts were accrued. Ph1b treated 7 pts at DL1, 6 were DLT evaluable, and no DLTs were observed. Ph2 enrolled and treated 9 pts at DL1 before concerns of delayed count recovery led to the reduction of the Ph2 dose of TP-0903 to DL-1 (25 mg/day). For all 16 pts treated at DL1, 1 pt achieved CR, 4 pts CRh, and 1 pt CRi, for a composite CR (CR/CRh/CRi) rate of 37.5% (95% CI, 15.2-64.6), with 4 pts achieving MRD negativity by central flow cytometry. For the remaining 10 pts, 1 pt achieved MLFS (6%), 6 pts had stable disease (37.5%), 1 pt had treatment failure (6%), and 2 pts were not evaluable (12.5%) due to withdrawal of consent and death from early disease progression. Two pts (1 CR and 1 CRh) proceeded to stem cell transplantation. The most common grade 3 and above treatment-related AEs include decreased neutrophil counts (37.5%), platelet counts (31.3%), and anemia (18.8%). Finally, PK and correlative data analysis looking at soluble Axl and Gas6 also supported reduction to DL-1. Conclusions: Initial results with DL1 suggest that TP-0903/dec shows preliminary clinical activity in the prognostically poor TP53m/complex karyotype AML sub-group, with 4 pts achieving MRD negative status out of 6 patients who achieved a CR/CRh/CRi (66%). After further patients were treated on DL1, the toxicity profile and correlative data supported the de-escalation to DL-1 as the RP2D. The Ph2 study is ongoing to determine the clinical activity of this new RP2D (DL-1). Clinical trial information: NCT03013998.

7500 Background: Increased selectivity of the Bruton tyrosine kinase inhibitor (BTKi) acalabrutinib (Aca) vs ibrutinib (Ib) may improve tolerability. We conducted an open-label, randomized, noninferiority, phase 3 trial to compare Aca vs Ib in patients (pts) with chronic lymphocytic leukemia (CLL). Methods: Previously treated CLL pts with del(17p) or del(11q) by central lab were randomized to receive oral Aca 100 mg BID or Ib 420 mg QD (stratified by del(17p) status, ECOG PS [2 vs ≤1], and number of prior therapies [1–3 vs ≥4]) until progression or unacceptable toxicity. Primary endpoint was progression-free survival (PFS) as assessed by IRC; secondary endpoints of all grade atrial fibrillation (AF), grade ≥3 infection, Richter transformation, and overall survival (OS) were assessed in hierarchical order. Results: 533 pts (Aca, n=268; Ib, n=265) were randomized (median age 66 y; median 2 prior therapies; del(17p) 45.2%; del(11q) 64.2%). At a median follow-up of 40.9 mo (range 0.0–59.1), Aca was noninferior to Ib with a median PFS of 38.4 mo in both arms (HR 1.00; 95% CI 0.79–1.27). Aca was statistically superior to Ib in all-grade AF incidence (9.4% vs 16.0%; P=0.023). Among the other secondary endpoints, incidences of grade ≥3 infection (Aca: 30.8%, Ib: 30.0%) and Richter transformation (Aca: 3.8%, Ib: 4.9%) were comparable between arms. Median OS was not reached in either arm (HR 0.82 [95% CI 0.59–1.15]), with 63 (23.5%) deaths in the Aca arm and 73 (27.5%) in the Ib arm. Among any-grade AEs in ≥20% of pts in either arm, Aca was associated with a lower incidence of hypertension (9.4%, 23.2%), arthralgia (15.8%, 22.8%), and diarrhea (34.6%, 46.0%) but a higher incidence of headache (34.6%, 20.2%) and cough (28.9%, 21.3%). AEs led to treatment discontinuation in 14.7% of Aca- vs 21.3% of Ib-treated pts. Among any-grade events of clinical interest, cardiac, hypertension, and bleeding events were less frequent with Aca (Table). Conclusions: In this first head-to-head trial of BTKis in CLL, Aca demonstrated non-inferior PFS with less cardiotoxicity and fewer discontinuations due to AEs vs Ib. Clinical trial information: NCT02477696. [Table: see text]

7509 Background: Early results from ELEVATE-TN (NCT02475681) at a median follow-up of 28.3 mo demonstrated superior efficacy of acalabrutinib (A) ± obinutuzumab (O) compared with O + chlorambucil (Clb) in patients (pts) with treatment-naïve (TN) chronic lymphocytic leukemia (CLL) (Sharman et al. Lancet 2020;395:1278-91). Results from a 4-year update are reported here. Methods: Pts received A±O or O+Clb. Crossover to A monotherapy was permitted in pts who progressed on O+Clb. Investigator-assessed (INV) progression-free survival (PFS), INV overall response rate (ORR), overall survival (OS), and safety were evaluated. Results: 535 pts (A+O, n=179; A, n=179; O+Clb, n=177) were randomized with a median age of 70 y; 63% had unmutated IGHV and 9% del(17p). At a median follow-up of 46.9 mo (range, 0.0–59.4; data cutoff: Sept 11, 2020), the median PFS was not reached (NR) for A+O and A pts vs 27.8 mo for O+Clb pts (both P

Purpose Therapeutic targeting of Bruton tyrosine kinase (BTK) with ibrutinib in chronic lymphocytic leukemia has led to a paradigm shift in therapy, and relapse has been uncommon with current follow-up. Acquired mutations in BTK and PLCG2 can cause relapse, but data regarding the prevalence and natural history of these mutations are limited. Patients and Methods Patients accrued to four sequential studies of ibrutinib were included in these analyses. Deep sequencing for BTK and PLCG2 was performed retrospectively on patients who experienced relapse and prospectively on a screening population. Results With a median follow-up time of 3.4 years, the estimated cumulative incidence of progression at 4 years is 19% (95% CI, 14% to 24%). Baseline karyotypic complexity, presence of del(17)(p13.1), and age less than 65 years were risk factors for progression. Among patients who experienced relapse, acquired mutations of BTK or PLCG2 were found in 85% (95% CI, 71% to 94%), and these mutations were detected an estimated median of 9.3 months (95% CI, 7.6 to 11.7 months) before relapse. Of a group of 112 patients examined prospectively, eight patients have experienced relapse, and all of these patients had acquired resistance mutations before relapse. A resistance mutation was detected in an additional eight patients who have not yet met criteria for clinical relapse. Conclusion Relapse of chronic lymphocytic leukemia after ibrutinib is an issue of increasing clinical significance. We show that mutations in BTK and PLCG2 appear early and have the potential to be used as a biomarker for future relapse, suggesting an opportunity for intervention.

e19510 Background: Over 40% of newly diagnosed acute leukemia patients receiving induction therapy develop acute respiratory failure. Bronchoscopy is a valuable tool for evaluating airway disease, but its diagnostic yield in this setting has not been fully explored. Methods: We performed a retrospective chart review of 75 newly diagnosed acute leukemia patients who had bronchoscopies. Data recorded prior to bronchoscopy included age, diagnosis, induction treatment regimen, chest imaging, assisted ventilation, duration of neutropenia and antibiotic therapy and microbiological studies. Bronchoalveolar lavage (BAL) cultures were sorted by organism, as well as by other pathologic findings. The primary outcome was antibiotic change supported by culture data. Results: The study population is summarized in the table. Induction regimen backbones included 7+3 (51), 7+4+ATRA (2), decitabine (12), hyperCVAD (2), AYA (3), other (1) and none (4); 18 patients were treated on clinical trial. Average days of neutropenia was 10.92 and average days of antibiotic therapy was 10.57. Thirty-eight patients had chest infiltrates, 11 received NIPPV, and 17 were mechanically ventilated. We identified 24 patients with +BAL studies. Of these, 37.5% (9) had + blood, urine or sputum studies before bronchoscopy, but only 3 had cultures positive for the same organism as the BAL. Of 51 patients with –BAL studies, 33.3% (17) had prior negative cultures. Infections were most commonly bacterial (15, 62.5%), followed by viral (5, 20.8%) and fungal (4, 16.7%). The most common organisms were rhinovirus, vancomycin sensitive Enterococcus (4, 16.7% each) followed by VRE, Candida albicans and MRSA (2, 8.3% each). Five patients (6.7%) had alveolar hemorrhage. Of the 24 patients with +BAL cultures, bronchoscopy findings supported changing antibiotics in 18. In contrast, antibiotics were changed in 16 patients without +BAL cultures. Conclusions: We investigated the utility of bronchoscopy on AL patients during their initial admission. BAL cultures were positive in 32% of newly diagnosed AL patients undergoing bronchoscopy. However, +BAL cultures identified a new organism in 87.5% and guided antibiotic therapy in 75% of these patients. Further studies will be needed to establish predictors of bronchoscopy findings in this patient population. [Table: see text]

8024 Background: The next-generation Bruton tyrosine kinase inhibitor acalabrutinib was approved in patients (pts) with treatment-naïve (TN) and relapsed/refractory chronic lymphocytic leukemia (CLL)/small lymphocytic lymphoma (SLL) based on two complementary phase 3 studies, ELEVATE-TN and ASCEND. This report of ACE-CL-001 (NCT02029443), the first phase 2 study of acalabrutinib, provides the longest safety and efficacy follow-up to date in symptomatic TN CLL pts. Methods: Adults with TN CLL/SLL were eligible if they met iwCLL 2008 criteria for treatment, were inappropriate for/declined standard chemotherapy and had ECOG performance status 0–2. Pts received acalabrutinib 100 mg BID or 200 mg QD, later switching to 100 mg BID, until progressive disease (PD) or unacceptable toxicity. Primary endpoint was safety. Events of clinical interest (ECI) were based on combined AE terms for infections, bleeding events, hypertension, and second primary malignancies (SPM) excluding non-melanoma skin, and on a single AE term for atrial fibrillation. Additional endpoints included investigator-assessed overall response rate (ORR), duration of response (DOR), time to response (TTR), and event-free survival (EFS). Results: Ninety-nine pts (n = 62 100 mg BID; n = 37 200 mg QD), were treated [median age: 64 years, 47% Rai stage 3–4 disease, 10% del(17p), 62% unmutated IGHV]. At median follow-up of 53 months (range, 1–59), 85 (86%) pts remain on treatment; most discontinuations were due to AEs (n = 6) or PD (n = 3 [n = 1 Richter transformation]). Most common AEs (any grade) were diarrhea (52%), headache (45%), upper respiratory tract infection (44%), arthralgia (42%), and contusion (42%). All-grade and grade ≥3 ECIs included infection (84%, 15%), bleeding events (66%, 3%), and hypertension (22%, 11%). Atrial fibrillation (all grades) occurred in 5% of pts (incidence: 1% in years 1, 2, 4; 3% in year 3). SPMs excluding non-melanoma skin (all grades) occurred in 11%. Serious AEs were reported in 38% of pts; those in > 2 pts were pneumonia (n = 4) and sepsis (n = 3). ORR was 97% (7% complete response; 90% partial response). Median TTR was 3.7 months (range, 2–22). Response rates were similar across high-risk groups. Median DOR and median EFS were not reached; 48-month DOR rate was 97% (95% CI, 90%–99%), and 48-month EFS rate was 90% (95% CI, 82%–94%). Conclusions: Long-term data from ACE-CL-001 further support the favorable results with acalabrutinib in phase 3 studies and demonstrate durable responses with no new long-term safety issues. Clinical trial information: NCT02029443 .

e20004 Background: IB is a Bruton’s tyrosine kinase inhibitor that showed superior progression-free survival compared with BR in CLL patients (pts) 65 years or older in a randomized phase 3 trial (Woyach et al, NEJM 2018). Pts receiving IB had higher rates of atrial fibrillation (AFIB) and hypertension (HTN); BR pts had higher rates of hematologic toxicity. Differences in treatment duration for BR (6 cycles) and IB (until progression) complicated adverse event (AE) comparisons. Here we use an exploratory approach to compare toxicity burden between arms and provide assessment of AFIB, HTN and infections (INF). Methods: AEs were reported for each of cycles 1-6 and then every 3 cycles until progression or nonprotocol CLL therapy. Only grade (gr) 3-4 AEs were reported thereafter until death. A simple global AE score was calculated for each pt by summing grades of all gr 1-4 AEs and dividing by the number of cycles over which AEs were submitted. Results: 537 pts began therapy (176 BR, 361 IB). 68% on BR completed all 6 cycles. At a median follow-up of 38 months, 64% remained on IB. Treatment discontinuation for AE occurred in 10% and 14% of BR and IB pts. Overall, median AE score was 1.8 (interquartile range (IQR) 0.9-3.3) and 3.8 (IQR 2.3-5.9) in BR and IB arms (p < 0.01). For cycles 1-6, median AE score was 6.2 (IQR 3.8-9.0) and 4.8 (IQR 3.0-7.2) in BR and IB arms (p < 0.01). In the IB arm, median AE score post 6 cycles decreased significantly to 3.4 (IQR 1.9-5.6) (p < 0.01). Gr 3 or higher cumulative rates of AFIB, HTN, and INF over time appear in the table. 100 pts (26/176 BR, 74/361 IB) had 137 severe INF (39% respiratory: 16 BR, 37 IB; 25% skin: 3 BR, 31 IB; 12% GU: 3 BR, 13 IB; 25% other: 12 BR, 22 IB). There were 7 gr 5 INF (3 BR, 4 IB), none confirmed fungal. Conclusions: There was no difference in treatment discontinuation rates for AE. Overall toxicity burden was significantly higher for IB, although IB toxicity burden decreased after 6 cycles. Toxicity burden was significantly higher in cycles 1-6 for pts receiving BR. Risk of severe AFIB, HTN, and INF is highest in the first year of IB. A simple AE score provides valuable information, especially when evaluating regimens of varying length. Clinical trial information: NCT01886872 . Support: U10CA180821, U10CA180882, U24CA196171; https://acknowledgments.alliancefound.org ; Pharmacyclics; ClinicalTrials.gov Identifier: NCT01886872. [Table: see text]

8064 Background: Acala is a next-generation, highly selective, covalent Bruton tyrosine kinase inhibitor approved in the US for patients (pts) with chronic lymphocytic leukemia (CLL)/small lymphocytic lymphoma (SLL) and previously treated mantle cell lymphoma (MCL). We evaluated the safety profile of acala monotherapy (monotx) in multiple B cell malignancies. Methods: Data from pts with activated B-cell diffuse large B-cell lymphoma, CLL, follicular lymphoma, MCL, multiple myeloma, prolymphocytic leukemia, Richter syndrome, SLL, or Waldenström macroglobulinemia treated with ≥1 dose of acala monotx in 9 studies were pooled. Acala was administered at 100 mg BID in most pts (100–400 mg total dose daily). Adverse events (AE) were assessed. Results: A total of 1040 pts were included (median age: 67 y [range: 32–90]; ECOG status ≤1: 93%; median exposure duration: 24.6 mo [range: 0–58.5]). A total of 360 (34%) pts discontinued acala, most commonly due to progressive disease (PD; 17%). AEs led to acala discontinuation in 97 (9%) pts; those in > 2 pts were pneumonia (n = 5) and thrombocytopenia (n = 4). Incidence of AEs, including the most common (any grade and grade ≥3), are shown in the Table. Events of clinical interest (ECIs) included atrial fibrillation (afib) of any grade in 46 (4%) pts and grade ≥3 in 13 (1%) pts; major hemorrhage (any grade) in 37 (4%) pts; grade ≥3 infection in 183 (18%) pts; hypertension (any grade) in 79 (8%) pts and grade ≥3 in 36 (4%) pts; and second primary malignancies (SPM) excluding non-melanoma skin cancer (NMSC; any grade) in 68 (7%) pts. Median (range) time to first onset in days for each ECI (any grade) was: afib, 522 (8–1280); major hemorrhage, 293 (4–1327); infections, 92 (1–1317); hypertension, 157 (2–1345); SPM excluding NMSC, 339 (7–1499). Death was reported in 139 (13%) pts, most commonly due to PD (6%) and AEs (5%). Conclusions: Acala monotx has a favorable tolerability profile with increased exposure across multiple mature B cell malignancies. Additional analyses will further explore the longitudinal characteristics of AEs. [Table: see text]

7515 Background: Therapy-related AML (tAML) is a long-term complication of cytotoxic cancer therapy. It is characterized by adverse genetics and inferior survival outcomes when compared to de novo AML. A proposed mechanism in tAML pathogenesis includes treatment-induced selection of clones harboring pre-existing mutations (i.e. clonal hematopoiesis, CH). We hypothesize that genotoxic therapies used to treat prior malignancy drive leukemogenesis through different mechanisms leading to unique clonal compositions. Methods: AML patients (pts) treated at The Ohio State University between 2015-2018 were included. Genetic profiling was performed using Miseq Illumina platform with a 49-gene targeted sequencing panel at our clinical laboratory. Results: We studied 337 AML pts (Table), of whom 53% had smoking history. Mutations involving ASXL1 were more common in smokers vs non-smokers (14% vs 5.8%, p= .001), while JAK2 mutations were more common in non-smokers (8% vs 1.2%, p= .003). Regarding specific genotoxic therapies and mutations in tAML, we investigated common CH-associated mutations including DNMT3A, TET2, and ASXL1 (DTA mutations). In tAML pts, those exposed to radiotherapy experienced a higher frequency of DTA (52% vs 27%, p= .05), NPM1 (21% vs 0%, p= .002), and SRSF2 (15% vs 0%, p= .01) mutations, and conversely, a lower incidence of TP53 mutations (21% vs 46%, p= .04). Pts with history of cytotoxic chemotherapy had a lower incidence of DTA mutations, including those who received platinum agents (8% vs 49%, p= .005) and taxanes (7% vs 52%, p< .001), but had a higher incidence of TP53 mutations (75% vs 25%, p< .001 for platinum; 53% vs 25%, p= .04 for taxanes). Similarly, alkylators and anthracyclines were associated with lower incidence of DNMT3A (0% vs 20%, p= .009) and ASXL1 (0% vs 12.5%, p= .04) mutations. Conclusions: Different genotoxic agents demonstrate unique effects in leukemia development. Our data suggest that CH clones with DTA mutations may be enriched with smoking and radiotherapy, while cytotoxic chemotherapy may confer a higher incidence of TP53 mutations. Given the adverse prognosis of TP53 mutated AML, identification of pre-existing CH clones might influence treatment selection in solid tumor pts receiving anticancer therapy. [Table: see text]

Purpose Chemoimmunotherapy has been the standard of care for chronic lymphocytic leukemia (CLL). However, the introduction of B-cell receptor (BCR) kinase inhibitors such as ibrutinib has the potential to eliminate the role of chemotherapy in the treatment of CLL. How to best incorporate old and new therapies for CLL in this landscape is increasingly complex. Methods This article reviews current data available to clinicians and integrates these data to provide a strategy that can be used to approach the treatment of CLL in the era of BCR signaling inhibitors. Results Current strategies separate patients based on age or functional status as well as genetics [presence or absence of del(17)(p13.1)]. In the era of targeted therapy, this will likely continue based on current available data. Phase III studies support chemoimmunotherapy as the initial standard therapy for patients without del(17)(p13.1). Choice of chemotherapy (fludarabine plus cyclophosphamide, bendamustine, or chlorambucil) and anti-CD20 antibody (rituximab, ofatumumab, or obinutuzumab) varies based on regimen and patient status. For patients with del(17)(p13.1), no standard initial therapy exists, although several options supported by phase II clinical trials (methylprednisolone plus alemtuzumab or ibrutinib) seem better than chemoimmunotherapy. Treatment of relapsed CLL seems to be best supported by ibrutinib-based therapy. Completion of trials with ibrutinib and other new agents in the near future will offer opportunity for chemotherapy-free treatment across all groups of CLL. Conclusion Therapy for CLL has evolved significantly over the past decade with introduction of targeted therapy for CLL. This has the potential to completely transform how CLL is treated in the future.

7510 Background: Ibrutinib (ibr), a first-in-class, once-daily Bruton’s tyrosine kinase inhibitor, has redefined treatment paradigms for CLL/SLL. We report final analysis with up to 6 years of follow-up on ibr from the phase 3 RESONATE study of single-agent ibr vs ofatumumab (ofa) in pts with relapsed/refractory (R/R) CLL/SLL. Methods: Pts were randomized to receive oral ibr 420 mg daily until PD or intravenous ofa for up to 24 weeks. Long-term efficacy endpoints were investigator-assessed. Results: Among 391 pts randomized to receive ibr (n=195) or ofa (n=196), 86% and 79%, respectively, were in the genomic high-risk population (del(17p), del(11q), TP53 mutation, and/or unmutated IGHV). At final analysis, median follow-up was 64 mo (range, 0.3-72) on ibr. Of pts randomized to ofa, 68% crossed over to receive ibr. Significant sustained PFS benefit was observed with ibr vs ofa, with median PFS 44.1 vs 8.1 mo (HR 0.15; 95% CI 0.11-0.20; P˂0.0001) and was consistent across baseline subgroups. Median PFS in genomic high-risk population was 44.1 vs 8.0 mo on ibr vs ofa (HR 0.11; 95% CI 0.08-0.15). ORR with ibr was 88% (CR/CRi in 11%). Initial ibr treatment conferred better OS than ofa when censored for crossover (HR 0.64; 95% CI 0.42-0.98). Median duration of ibr was 41 mo (range 0.2-71); 41% of pts received ibr >4 yrs. AE profile with ibr remained consistent with prior reports. Cumulatively during long-term ibr therapy, all-grade (grade ≥3) hypertension and atrial fibrillation occurred in 21% (9%) and 12% (6%) of pts, respectively; major hemorrhage occurred in 10%. Most common reasons for ibr discontinuation (DC) prior to study closure were PD (37%) and AEs (16%); DC due to AEs occurred in 6%, 3%, 4%, 4%, 6% and 4% of pts during yrs 0-1, 1-2, 2-3, 3-4, 4-5 and 5-6, respectively. Conclusions: With up to 6 years of follow-up, extended ibr treatment showed sustained efficacy in pts with R/R CLL, including in pts with high-risk genomic features. Safety remained acceptable with low rates of DC due to AEs, and with no new safety signals over long-term therapy. These results establish long-term benefit and tolerability for continuous ibr treatment in pts with R/R CLL. Clinical trial information: NCT01578707.

TPS7566 Background: Despite treatment advances, CLL is largely incurable. First-line targeted therapy with ibrutinib mostly produces durable remissions, but high-risk disease or many prior therapies increases relapse risk (Ghia P, et al. Haematologica. 2014). Relapse after ibrutinib is associated with a poor outcome (Maddocks KJ, et al. JAMA Oncol. 2015). Allogeneic stem cell transplantation potentially offers long-term remissions but has a high risk of morbidity/mortality (Shustik C, et al. Ann Hematol. 2017). Autologous T cells expressing a CD19-specific chimeric antigen receptor (CAR) with a CD28 costimulatory domain may be efficacious against CLL (Kochenderfer JN, et al. Blood. 2012). KTE-X19 is an autologous anti-CD19 CAR T cell therapy under investigation for R/R hematologic malignancies and may offer longer durable remissions with manageable safety in pts with R/R CLL. ZUMA-8 is a Phase 1/2 multicenter study for pts with R/R CLL. Methods: Adult pts must have R/R CLL with ≥ 2 prior treatment regimens, disease progression on ibrutinib, ECOG 0-1, and adequate organ function. Phase 1 will enroll 12-18 pts to assess dose-limiting toxicities (DLTs) with a 6 + 3 dose escalation/de-escalation design; 30 more pts may be enrolled to further assess safety. Phase 2 will enroll ≈60 pts to evaluate efficacy and safety. Pts will undergo leukapheresis followed by optional bridging therapy. Cyclophosphamide (500 mg/m2) and fludarabine (30 mg/m2) conditioning chemotherapy will be given on Days -5, -4 and -3. KTE-X19 will be given on Day 0 at 0.5, 1 or 2 × 106 KTE-X19 cells/kg. The primary endpoint is incidence of DLTs for Phase 1 and independent review committee-assessed objective response rate (ORR) per iwCLL 2018 criteria for Phase 2. Secondary endpoints include complete remission (CR) rate, investigator-assessed ORR, minimal residual disease (MRD) negativity rate, MRD-negative CR rate, duration of response, progression-free survival, overall survival, safety, and patient-reported outcomes (Phase 2). Serum cytokine and blood KTE-X19 cell levels over time and level of anti-KTE-X19 antibodies are exploratory endpoints. Accrual is ongoing. Clinical trial information: NCT03624036.

TPS7572 Background: Inhibition of Bruton tyrosine kinase (BTK) has emerged as a strategy for targeting B-cell malignancies including CLL/SLL. Zanubrutinib, an investigational inhibitor of BTK, was specifically engineered to optimize selectivity, half-life and solubility in an effort to decrease toxicities and better penetrate tumor tissue. Early clinical data suggested that zanubrutinib treatment in patients with treatment-naïve (TN; n = 16) or R/R (n = 50) CLL/SLL induced deep responses: 94% overall response rate (ORR), including 6% and 2% complete response rates in TN and R/R CLL/SLL, respectively (ICML 2017). This study is designed to evaluate whether zanubrutinib monotherapy exhibits non-inferior and potentially superior efficacy based on the ORR vs ibrutinib monotherapy in patients with R/R CLL/SLL. Methods: This ongoing phase 3, randomized, open-label, global study (NCT03734016, BGB-3111-305) is comparing the efficacy and safety of zanubrutinib vs ibrutinib in adult patients with R/R CLL/SLL. Approximately 400 patients will be randomized, 1:1 to each arm and stratified by age (< 65 vs ≥ 65 years), refractory status (yes vs no), geographic region, and del(17p)/ TP53 mutation status (present vs absent). Key inclusion criteria include R/R CLL/SLL requiring treatment per iwCLL criteria, ECOG PS 0-2, and adequate hematologic function. The primary endpoint is ORR as determined by an independent review committee according to iwCLL guidelines, with modification for treatment-related lymphocytosis for patients with CLL and per 2014 Lugano Classification for patients with SLL. The study is powered to test the non-inferiority and superiority of the ORR for zanubrutinib vs ibrutinib. Secondary endpoints include progression-free survival, safety, duration of response, and overall survival. Recruitment is ongoing. Clinical trial information: NCT03734016.

Purpose Chronic lymphocytic leukemia (CLL) is a disease of the elderly, yet few clinical trials include a significant number of older patients, and outcomes after specific therapies can be different depending on age. Patients and Methods We examined patients enrolled onto successive first-line CALGB CLL trials to determine whether efficacy of regimens varied by age, focusing on ideal chemotherapy choice and benefit of immunotherapy addition to chemotherapy in older patients. Regimens included chlorambucil, fludarabine, fludarabine plus rituximab (FR), fludarabine with consolidation alemtuzumab, and FR with consolidation alemtuzumab. Results A total of 663 patients were evaluated for response, progression-free survival (PFS), and overall survival (OS) by age group. Interaction effects of fludarabine versus chlorambucil by age group (PFS, P = .046; OS, P = .006) showed that among patients younger than 70 years, PFS and OS was improved with fludarabine over chlorambucil (PFS: hazard ratio [HR] = 0.6, 95% CI, 0.5 to 0.8; OS: HR = 0.7, 95% CI, 0.5 to 0.9), but not in older adults (PFS, HR = 1.0, 95% CI, 0.6 to 1.7; OS: HR = 1.5, 95% CI, 0.9 to 2.3). In contrast, FR improved outcomes relative to fludarabine, irrespective of age (PFS: HR = 0.6, 95% CI, 0.4 to 0.7; OS: HR = 0.7, 95% CI, 0.5 to 0.9). Alemtuzumab consolidation did not provide benefit over similar regimens without alemtuzumab (P > .20), irrespective of age. Conclusion These data support the use of chlorambucil as an acceptable treatment for many older patients with CLL and suggest rituximab is beneficial regardless of age. These findings bear relevance to both routine care of CLL patients 70 years and older and also future clinical trials in this population.

Purpose The addition of rituximab to fludarabine-based regimens in chronic lymphocytic leukemia (CLL) has been shown to produce high response rates with extended remissions. The long-term follow-up of these regimens with respect to progression, survival, risk of secondary leukemia, and impact of genomic risk factors has been limited. Methods We report the long-term follow-up of the chemoimmunotherapy trial CALGB 9712 from the Cancer and Leukemia Group B, for which treatment regimen was previously reported, to examine end points of progression-free survival (PFS), overall survival (OS), impact of genomic features, and risk of therapy-related myeloid neoplasm (t-MN). Results A total of 104 patients were enrolled on this study and now have a median follow-up of 117 months (range, 66 to 131 months). The median OS was 85 months, and 71% of patients were alive at 5 years. The median PFS was 42 months, and 27% were progression free at 5 years. An estimated 13% remained free of progression at almost 10 years of follow-up. Multivariable models of PFS and OS showed that immunoglobulin heavy chain variable region mutational status was significant for both, whereas cytogenetic abnormalities were significant only for OS. No patient developed t-MN before relapse. Conclusion Long-term follow-up of CALGB 9712 demonstrates extended OS and PFS with fludarabine plus rituximab. Patients treated with fludarabine plus rituximab administered concurrently or sequentially have a low risk of t-MN. These long-term data support fludarabine plus rituximab as one acceptable first-line treatment for symptomatic patients with CLL.

Purpose Lenalidomide is effective in myeloma and low-risk myelodysplastic syndromes with deletion 5q. We report results of a phase I dose-escalation trial of lenalidomide in relapsed or refractory acute leukemia. Patients and Methods Thirty-one adults with acute myeloid leukemia (AML) and four adults with acute lymphoblastic leukemia (ALL) were enrolled. Lenalidomide was given orally at escalating doses of 25 to 75 mg daily on days 1 through 21 of 28-day cycles to determine the dose-limiting toxicity (DLT) and maximum-tolerated dose (MTD), as well as to provide pharmacokinetic and preliminary efficacy data. Results Patients had a median age of 63 years (range, 22 to 79 years) and a median of two prior therapies (range, one to four therapies). The DLT was fatigue; 50 mg/d was the MTD. Infectious complications were frequent. Plasma lenalidomide concentration increased proportionally with dose. In AML, five (16%) of 31 patients achieved complete remission (CR); three of three patients with cytogenetic abnormalities achieved cytogenetic CR (none with deletion 5q). Response duration ranged from 5.6 to 14 months. All responses occurred in AML with low presenting WBC count. No patient with ALL responded. Two of four patients who received lenalidomide as initial therapy for AML relapse after allogeneic transplantation achieved durable CR after development of cutaneous graft-versus-host disease, without donor leukocyte infusion. Conclusion Lenalidomide was safely escalated to 50 mg daily for 21 days, every 4 weeks, and was active with relatively low toxicity in patients with relapsed/refractory AML. Remissions achieved after transplantation suggest a possible immunomodulatory effect of lenalidomide, and results provide enthusiasm for further studies in AML, either alone or in combination with conventional agents or other immunotherapies.

7512Background: Therapies are urgently needed for patients (pts) with CLL relapsed/refractory (R/R) to BCRi. We report outcomes for the full trial population from an ongoing phase 2 trial with VEN ...

7514Background: While it has been established that attainment of a complete response (CR) after chemoimmunotherapy improves progression free survival (PFS), this has not been proven with the BTK in...

7521Background: B2M is often elevated in pts with CLL and correlates with disease stage and burden. Normalization of B2M at 6 mo during ibr treatment was associated with improved progression-free s...

7048Background: Patients (pts) with relapsed or refractory (R/R) acute myeloid leukemia (AML) have limited treatment options. Selinexor (SEL), an oral inhibitor of the nuclear transport protein XPO...

7528Background: Venetoclax (VEN) is highly effective for the treatment of chronic lymphocytic leukemia (CLL). Tumor lysis syndrome (TLS) during VEN initiation is a major risk and management, includ...

7532Background: The CLL literature focuses largely on the objective aspects of diagnosis (dx), active observation (AO), prognosis and management. While health care providers (HCPs) try to effective...

PurposeLenalidomide is a novel therapeutic agent with uncertain mechanism of action that is clinically active in myelodysplastic syndrome (MDS) and multiple myeloma (MM). Application of high (MM) and low (MDS) doses of lenalidomide has been reported to have clinical activity in CLL. Herein, we highlight life-threatening tumor flare when higher doses of lenalidomide are administered to patients with CLL and provide a potential mechanism for its occurrence.Patients and MethodsFour patients with relapsed CLL were treated with lenalidomide (25 mg/d for 21 days of a 28-day cycle). Serious adverse events including tumor flare and tumor lysis are summarized. In vitro studies examining drug-induced apoptosis and activation of CLL cells were also performed.ResultsFour consecutive patients were treated with lenalidomide; all had serious adverse events. Tumor flare was observed in three patients and was characterized by dramatic and painful lymph node enlargement resulting in hospitalization of two patients, with one fatal outcome. Another patient developed sepsis and renal failure. In vitro studies demonstrated lenalidomide-induced B-cell activation (upregulation of CD40 and CD86) corresponding to degree of tumor flare, possibly explaining the tumor flare observation.ConclusionLenalidomide administered at 25 mg/d in relapsed CLL is associated with unacceptable toxicity; the rapid onset and adverse clinical effects of tumor flare represent a significant limitation of lenalidomide use in CLL at this dose. Drug-associated B-cell activation may contribute to this adverse event. Future studies with lenalidomide in CLL should focus on understanding this toxicity, investigating patients at risk, and investigating alternative safer dosing schedules.

Purpose Genomic features including unmutated immunoglobulin variable region heavy chain (IgVH) genes, del(11q22.3), del(17p13.1), and p53 mutations have been reported to predict the clinical course and overall survival of patients with chronic lymphocytic leukemia (CLL). In addition, ZAP-70 and Bcl-2 family proteins have been explored as predictors of outcome. Patients and Methods We prospectively evaluated the prognostic significance of a comprehensive panel of laboratory factors on both response and progression-free survival (PFS) using samples and data from 235 patients enrolled onto a therapeutic trial. Patients received either fludarabine (FL; n = 113) or fludarabine plus cyclophosphamide (FC; n = 122) as part of a US Intergroup randomized trial for previously untreated CLL patients. Results Complete response (CR) rates were 24.6% for patients receiving FC and 5.3% for patients receiving FL (P = .00004). PFS was statistically significantly longer in patients receiving FC (median, 33.5 months for patients receiving FC and 19.9 months for patients receiving FL; P < .0001). The occurrence of del(17p13.1) (hazard ratio, 3.428; P = .0002) or del(11q22.3) (hazard ratio, 1.904; P = .006) was associated with reduced PFS. CR and overall response rates were not significantly different based on cytogenetics, IgVH mutational status, CD38 expression, or p53 mutational status. Expression of ZAP-70, Bcl-2, Bax, Mcl-1, XIAP, Caspase-3, and Traf-1 was not associated with either clinical response or PFS. Conclusion These results support the use of interphase cytogenetic analysis, but not IgVH, CD38 expression, or ZAP-70 status, to predict outcome of FL-based chemotherapy. Patients with high-risk cytogenetic features should be considered for alternative therapies.

Purpose Several new prognostic factors predicting rapid disease progression in chronic lymphocytic leukemia (CLL) have been identified, including unmutated Ig VH mutational status, del(11)(q23), del(17)(p13.1), and p53 mutations. To date, the impact of these same prognostic factors have not been examined relative to treatment outcome with chemoimmunotherapy. Methods We examined the impact of these new prognostic factors on predicting treatment outcome in symptomatic, untreated CLL patients who received chemoimmunotherapy with fludarabine and rituximab as part of a completed, randomized phase II study, Cancer and Leukemia Group B (CALGB) 9712. Results Eighty-eight patients treated as part of CALGB 9712 had detailed prognostic factor assessment performed. Using Ig VH mutational status to classify risk, there was no association between complete response rate with either unmutated Ig VH mutational status or high-risk interphase cytogenetics. However, the median progression-free survival (PFS; P = .048) and overall survival (OS; P = .01) were shorter among the Ig VH unmutated patients as compared with the Ig VH mutated patients. Using the hierarchical classification of Döhner, PFS (P = .005) and OS (P = .004) were significantly longer as the classification moved from high risk [del (11)(q22.3) or del (17)(p13.1)] to low risk. Conclusion These data demonstrate that high-risk CLL patients characterized by Ig VH unmutated (≥ 98%) or high-risk interphase cytogenetics, including either del(17p) or del(11q), appear to have a shorter PFS and OS with chemoimmunotherapy. Larger prospective studies will be required to determine the independent influence of Ig VH mutational status and interphase cytogenetics on treatment outcome.

Purpose Chronic lymphocytic leukemia (CLL) is a clinically heterogeneous disease for which natural history can be predicted based on the presence or absence of immunoglobulin (Ig) variable heavy chain (VH) gene mutations. Herein we report selective epigenetic silencing of the transcription factor TWIST2 (DERMO1) in Ig VH mutated CLL and describe a semiquantitative assay to study promoter methylation of this gene in primary tumor cells. Materials and Methods TWIST2 promoter methylation was identified by restriction landmark genome scanning. Southern blot (SB), bisulfite sequencing, and combined bisulfite restriction analysis (COBRA), and quantitative SB-COBRA was performed to study methylation of the TWIST2 promoter. Reverse transcription polymerase chain reaction assays were used to study TWIST2 expression in CLL cells. Results Following identification and confirmation of TWIST2 methylation in CLL patients, we demonstrated that expression of this transcription factor is related to the degree of promoter methylation. Expression of TWIST2 in a CLL cell line in which the promoter is methylated was increased following decitabine treatment. We next studied 53 patients by COBRA and demonstrated that 72% of patient samples with mutated Ig VH show TWIST2 methylation, while only 16% of patient samples with unmutated Ig VH were methylated (P < .001). In a subset of patients, methylation of TWIST2 correlated with mRNA expression. Conclusion TWIST2 is differentially methylated in CLL cells relative to Ig VH mutational status and can be quantitatively monitored by SB-COBRA. Based on the known role of TWIST2 in silencing p53 function in other malignancies, future studies should focus on the role of TWIST2 in CLL and related lymphoproliferative diseases.

Purpose To study the impact of repetitive (three to four courses) versus a single course of high-dose cytarabine (HDAC) consolidation therapy on outcome of patients with acute myeloid leukemia (AML) and inv(16)(p13q22) or t(16;16)(p13;q22). Patients and Methods We examined the cumulative incidence of relapse (CIR), relapse-free survival (RFS), and overall survival (OS) for 48 adults younger than 60 years with inv(16)/t(16;16) who had attained a complete remission on one of four consecutive clinical trials and were assigned to receive HDAC consolidation therapy. Twenty-eight patients were assigned to either three or four courses of HDAC, and 20 patients were assigned to one course of HDAC followed by alternative intensive consolidation therapy. Results Pretreatment features were similar for the two groups. The CIR was significantly decreased in patients assigned to receive three to four cycles of HDAC compared with patients assigned to one course (P = .03; 5-year CIR, 43% v 70%, respectively). The difference in RFS also approached statistical significance (P = .06). In a multivariable analysis that adjusted for potential confounding covariates, only treatment assignment (three to four cycles of HDAC) predicted for superior RFS (P = .02). The OS of both groups was similar (P = .93; 5-year OS, 75% for the three to four cycles of HDAC group v 70% for the one cycle of HDAC group), reflecting a high success rate with stem-cell transplantation salvage treatment administered among patients in both treatment groups. Conclusion We conclude that, in AML patients with inv(16)/t(16;16), repetitive HDAC therapy decreases the likelihood of relapse compared with consolidation regimens including less HDAC.

Standardized criteria for response to therapy in patients with chronic lymphocytic leukemia (CLL), lymphoma, and other malignancies allow for comparisons of outcome between clinical trials and have facilitated regulatory agency approval of novel active agents for use in current standard therapy. In 1988, the National Cancer Institute (NCI) Working Group published the first widely accepted criteria for CLL,1 which were revised in 1996.2 Such recommendations were developed in the context of currently available cytotoxic therapies. Later, in 2008, the International Workshop on CLL published criteria that incorporated much of the 1996 guidelines but also included guidance on how to assess minimal residual disease after therapy.3 These published guidelines defined therapy outcome as either complete response (CR), partial response (PR), stable disease (SD), or progressive disease (PD), based on surrogate markers of tumor burden, such as blood lymphocyte count, lymph node size, or spleen size, and indicators of improved marrow function or clearance of leukemia cells from the marrow, as assessed by serial blood counts and/or marrow aspirate and biopsy. In general, these response criteria (CR, PR, SD, and PD) in therapeutic trials have correlated with the length of progression-free survival (PFS) and occasionally overall survival after treatment. Because assessment of response using these criteria can often be made years before survival data are available, response criteria have served as useful surrogate markers for assessing the clinical benefit of therapy, thereby accelerating the pace of approval of novel agents for use in the treatment of patients.

TPS7567 Background: Patients (pts) with R/R CLL who discontinue treatment with the BTKi ibrutinib due to progression have a particularly dismal prognosis. A phase I study showed that the Fc-enhanced, humanized, CD19 antibody MOR208 was well tolerated with encouraging single-agent activity in pts with R/R CLL/SLL. In preclinical models, MOR208 showed synergy with idelalisib (an inhibitor of PI3K delta) and venetoclax (an inhibitor of BCL-2), both approved for the treatment of CLL. Methods: This two-cohort, phase II study will investigate MOR208 combined with idelalisib (cohort A) or venetoclax (cohort B) in pts with R/R CLL or R/R SLL and includes a safety run-in phase for each cohort, to be evaluated by an Independent Data Monitoring Committee. Key inclusion criteria: aged ≥18 years, R/R CLL/SLL while receiving a BTKi therapy or intolerance of such therapy, BTKi administered as a single-agent or in combination for at least 1 month as the most recent prior anticancer therapy, ECOG performance status of 0–2, and adequate organ function. Key exclusion criteria: transformed CLL/SLL or Richter’s syndrome, BTKi treatment within 5 days prior to study drug dosing, prior treatment with a CD19-targeted therapy, a PI3K inhibitor (cohort A) or a BCL-2 inhibitor (cohort B). Pts will be treated for a maximum of 24 (28-day) cycles or until disease progression. Treatment will be MOR208 12 mg/kg IV (weekly for the first 3 months, every second week for the next 3 months, and monthly thereafter) in combination with oral idelalisib 150 mg twice-daily or venetoclax administered on a weekly ramp-up dosing schedule to the recommended daily dose of 400 mg. Primary endpoint: overall response rate based on independent review; secondary and exploratory endpoints include: progression-free and overall survival, duration of response, safety, pharmacokinetics, MOR208 immunogenicity, quality of life and minimal residual disease negativity. 120 pts per cohort are planned. Clinical trial information: 2015-002915-14.

7503 Background: Prior to use of novel targeted agents for CLL, debate existed regarding the best chemoimmunotherapy regimen to build upon in patients (pts) with non-del(11q) disease. The role of lenalidomide (L) was also not defined. CALGB 10404 was a randomized phase 2 study addressing these questions. Methods: Pts with untreated CLL requiring therapy were randomized to treatment with fludarabine + rituximab (FR), FR + 6 monthly consolidative treatments of L (5 mg days 1-21/28 x 1 then 10 mg days 1-21/28 x 5) (FR+L), or FR + cyclophosphamide (FCR). Based on pretreatment central interphase cytogenetic screening, pts with del(11q22.3) in at least 20% of cells were excluded from the primary analysis, testing whether 2-year progression-free survival (PFS) rate was improved in non-del(11q) pts within each arm. A target accrual of 103 non-del(11q) pts per arm provided at least 84% power to detect an increase in 2-year PFS rate from 60% to 73%; the critical value was 69% using a single stage design and type I error rate of 4%. Results: A total of 342 non-del(11q) CLL pts were randomized to treatment with FR (n = 123), FR+L (n = 109), or FCR (n = 110). Baseline characteristics were similar across arms. Two-year PFS rates with exact 90% CIs were 64% (57-71%) (FR), 71% (63-78%) (FR+L), and 74% (66-80%) (FCR). Median PFS was significantly shorter with FR compared to FR+L (p = 0.03) and FCR (p < 0.01): 43 (95% CI: 33-50), 66 (95% CI: 45-not reached), and 78 (95% CI: 58-not reached) months respectively. Median overall survival (OS) has not been reached for any arm. OS at 1, 2, and 3 years was similar across arms, although there was a plateau in OS with no events beyond 41 months in the FR+L arm, different from FR/FCR where events continued to occur. The most common adverse events were cytopenias and infections. Conclusions: FR+L and FCR met the protocol defined primary endpoint. FR+L extended PFS relative to FR and a plateau in survival differentiated this arm from the FR/FCR arms. Future studies comparing FR+L to FCR or incorporating L into other novel treatment regimens are justified. Support: U10CA180821, U10CA180882, Celgene. Clinical trial information: NCT00602459.

7509 Background: Immunotherapy with anti-CD19 CART cells induces complete remission (CR) in the minority of patients with CLL, but where CRs occur they tend to be durable. Based on preclinical evidence of synergy, we combined anti-CD19 CAR T cells with ibrutinib to test the hypothesis that pre- and concurrent treatment would enhance the CR rate. Methods: This is a pilot trial of anti-CD19 CAR T cells in adults with CLL/SLL who were not in CR despite at least 6 months of ibrutinib. Pts must have failed at least 1 regimen before ibrutinib, unless they had del(17)(p13.1) or a TP53 mutation. T cells were lentivirally transduced to express a CAR comprising CD3z, 4-1BB, and humanized anti-CD19 scFv (CTL119). Pts were lymphodepleted 1 week before infusion. Ibrutinib was continued throughout the trial. Results: Manufacturing was successful in all pts. Ten pts (9M, 1F; ages 47-77; 0-12 regimens prior to ibrutinib) have been infused. All had abnormalities of TP53 or ATM and two pts had increasing BTK C481S clones. Median marrow CLL burden was 10% (range 10-50%). The median follow-up is 6 months (range 0.5-9). Cytokine release syndrome (CRS) developed in 9 pts; gr1 in 2, gr2 in 6 and gr3 in 1 pt. One pt developed gr4 tumor lysis syndrome. Treatment of CRS with the IL-6 receptor antagonist tocilizumab was not required. At 3 months, 8 evaluable pts had achieved an MRD-ve marrow CR (89%) by 9-color flow, and all remain in marrow CR at last F/U. There was modest residual splenomegaly in 3/5 patients, and adenopathy resolved in 4/6 subjects with progression in 1/6. MRD assessment by deep sequencing will be presented. Conclusions: We observed 89% MRD-ve marrow CR in pts with high-risk CLL using a well-tolerated combination of CART cells and ibrutinib. Longer follow-up will reveal the durability of these results and could support evaluation of a first-line combination approach in an attempt to obviate the need for chronic therapy. Clinical trial information: NCT02640209.

7510 Background: Ibr, a first-in-class, once-daily inhibitor of Bruton’s tyrosine kinase, is FDA-approved for all pts with CLL/SLL. We report updated safety and efficacy results with up to 4 y follow-up from the ph III RESONATE trial of ibr vs ofatumumab (ofa). Methods: Pts had ≥1 prior therapy. Pts received 420 mg ibr PO until PD or ofa up to 24 wks. At interim analysis (median 9 mo follow-up), the DMC declared superiority of ibr vs ofa for PFS and OS, and ibr access was recommended for all ofa pts. Long-term follow-up efficacy endpoints are per investigator assessment. Ofa pts were censored at crossover for OS. Results: 391 pts were randomized to receive ibr (n = 195) or ofa (n = 196). Median age was 67 y (40% ≥70 y); 57% had Rai stage III/IV. With median follow-up of 44 mo (53 mo max) for ibr arm, PFS was significantly longer for ibr vs ofa (median NR vs 8 mo, [HR 0.133; P< 0.0001]; 3-y PFS 59% vs 3%) with significant benefit across subgroups. PFS with ibr for del11q subgroup trended to have the most favorable outcome; however, PFS was not statistically different for pts with del17p or del11q or without these FISH abnormalities. At analysis, with the majority of pts (68%) randomized to ofa crossing over to ibr, OS was longer for ibr vs ofa (median OS NR for either arm). The OS rate for ibr at 3 y was 74%. ORR for ibr was 91% with CR/CRi rates (now 9%) increasing over time. Baseline cytopenias improved with extended ibr therapy for hemoglobin (85%), platelet (95%), and absolute neutrophil counts (95%). AE profile of ibr was consistent with previous reports. Major hemorrhage, Gr ≥3 atrial fibrillation, and Gr ≥3 hypertension occurred in 6%, 6%, and 8% of pts, respectively, over a follow-up of up to 4 y. Incidence of most Gr ≥3 AEs decreased from y 1 vs y 2-3: neutropenia- 18% vs 8%; pneumonia- 11% vs 4%; atrial fibrillation- 4% vs 2%, respectively. Discontinuations were most frequently PD (27%) and AE (12%). At analysis, 90 ibr pts (46%) continue ibr on study. Conclusions: Long-term treatment with ibr in this international ph III RESONATE study is tolerable and continues to show sustained PFS and OS regardless of high-risk cytogenetics. Ph III results in relapsed del17p and del11q pts compare favorably to prior ph II reports. Clinical trial information: NCT01578707.

Experimental design of cancer therapeutics involves wellaccepted phases designed to establish safe dosing, assess efficacy, and determine relative effectiveness compared with standard regimens. Phase I testing allows identification of tolerable dosing and an administration schedule that is followed by phase II testing in a specific disease to examine safety and early efficacy. If acceptable toxicity and efficacy is observed in phase II testing, development may proceed down two different pathways to obtain regulatory approval for marketing within the United States. One pathway involves performance of phase III study(s) comparing the respectivenewagentwiththeacceptedstandardtreatment.Thisrandomized phase III design provides the best opportunity to examine patientbenefitwithrespecttoimprovementinremissionduration, survival, and disease symptoms along with early and late toxicities associated with each treatment. The second pathway is most appropriateforuseinconditionswherenogoodstandardoralternative therapy exists. These single-arm phase II studies are of sufficient size to adequately assess patient safety and provide evidence of patient benefit. However, this nonrandomized design lacks a control comparison, thereby introducing biases that can overestimatethebenefitofthetherapeuticagent.Asaconsequence

PURPOSE To discuss the predisposing risk factor for all forms of extramedullary leukemia (EML) and to review the clinical features, prognostic significance, and treatment strategies for primary EML and leukemia cutis (LC)/granulocytic sarcomas (GS) in the setting of acute nonlymphocytic leukemia (ANLL). METHODS A review of all reports published since 1965 related to all forms of extramedullary leukemia (LC, GS, gingival hypertrophy, and meningeal leukemia [ML]). RESULTS Several factors, including chromosomal abnormalities [t(8;21), inv(16)], cell-surface markers (CD56, CD2, CD4, CD7), French-American-British (FAB) subtype (M2, M4, M5), blast differentiation and maturation, patient nutritional status, age, cellular immune dysfunction, high presenting leukocyte count, and decreased blast Auer rods, have been associated with a higher incidence of EML. Of 154 published cases of primary EML identified, 71 (46%) were initially misdiagnosed. The addition of immunohistochemical stains can assist in preventing such misdiagnoses and should be included in all atypical lymphoma/carcinoma cases. Only one of the patients (3%) with primary EML did not progress to ANLL in the absence of chemotherapy. In contrast, 66% of patients who received chemotherapy for the primary EML never developed ANLL. The prognostic significance of EML at presentation and medullary relapse of ANLL is uncertain. Isolated extramedullary recurrence of ANLL always heralds bone marrow relapse and should be treated with reinduction chemotherapy. Close clinical follow-up observation is necessary to insure resolution of EML. Radiation therapy is an effective local treatment for resistant or symptomatic EML. CONCLUSION Many advances in diagnoses and treatment of EML have been made. Future investigations are needed to define the clinical significance of EML in patients with ANLL treated with modern chemotherapy or bone marrow transplantation.

7521Background: Btk is a kinase involved in B-cell receptor signaling and a critical therapeutic target in CLL. Acalabrutinib—an irreversible, selective Btk inhibitor has demonstrated clinical effi...

e19005Background: The clinical course of CLL is variable but can be predicted in part by recurrent cytogenetic abnormalities. BCL6 functions as a transcriptional repressor during germinal center fo...

TPS7572Background: Ibrutinib, a Bruton's tyrosine kinase inhibitor (BTKi), is an important treatment option for patients (pts) with CLL/SLL. Pts who progress early on ibrutinib are difficult to tre...

7520Background: Ibrutinib (ibr) is the first-in-class once daily Bruton’s tyrosine kinase inhibitor FDA approved for patients (pts) with CLL with ≥ 1 prior therapy. We evaluated outcomes with ibr b...

7530Background: BTK is an attractive target in CLL. Ibrutinib (IB), a first in class irreversible BTK inhibitor (BTKi), abrogates important survival signals in CLL by proximally blocking multiple p...

8532 Background: Idelalisib (Zydelig), a selective oral inhibitor of PI3Kδ, demonstrated considerable anti-tumor activity in patients with relapsed/refractory iNHL in phase 1 (p1; Flinn, 2014), and...

The international Prognostic Index for patients with CLL (CLL-IPI) : An international meta-analysis

7012 Background: Ibrutinib (ibr), a first-in-class, once-daily, oral, covalent inhibitor of Bruton’s tyrosine kinase (BTK), is rapidly eliminated from plasma after oral administration (Advani, JCO ...

7072 Background: PI3K-δ and PI3K-γ play complementary roles in malignant B-cells and the tumor microenvironment (TME). Inhibition of PI3K-δ blocks cytokine-mediated CLL proliferation, while inhibit...

7074 Background: Signaling via PI3K-δ and PI3K-γ has distinct and complementary effects on malignant B-cells and nonmalignant immune cells in chronic lymphocytic leukemia (CLL). Duvelisib, an oral ...

TPS7100 Background: Abrogating B-cell receptor pathway signaling through BTK inhibition is an effective treatment strategy for CLL. However, some patients (pts) do not respond, or progress despite ...

7009 Background: Ibrutinib (Ib), an oral covalent BTK inhibitor, has significant activity in relapsed/refractory (R/R) CLL. Adding ofatumumab (O), an anti-CD20 antibody, to chemotherapy in CLL can improve response and progression free survival (PFS). Here, Ib was given with O in 3 different administration sequences. Methods: Patients (pts) with R/R CLL/SLL, PLL or Richter’s transformation (RT) after ≥2 prior therapies including a purine analog were treated with 420 mg Ib daily and 300/2000 mg O (8 x weekly/then 4 x monthly) in 28-day cycles until progressive disease (PD). Group (G) 1 had 1 cycle of Ib monotherapy, then O was added. G2 started O on Day (D) 1/Cycle (C) 1 and Ib on D2/C1. G3 had 2 cycles of O monotherapy, then Ib was added on D1/C3. Results: 71 pts (27, 20, 24 in G1, 2, 3) were enrolled. Median age was 64 y; 61% had Rai stage III/IV; 65 pts had CLL, 1 SLL, 2 PLL and 3 RT; 75% had lymph nodes ≥5 cm; 44% had del(17p); 31% had del(11q). The most frequent AEs were diarrhea (68%), infusion-relate...

7087 Background: Chronic lymphocytic leukemia (CLL) patient outcomes may benefit from targeting therapies alone or in combination to individuals with favorable molecular profiles. Whether such pers...

7014 Background: CLL/SLL is generally very responsive to chemoimmunotherapy. However, relapses occur and resistance develops. In particular, del(17p) is associated with poor outcomes using all curr...