LaPlant, Betsy

Abstract Bortezomib, a proteasome inhibitor (PI), has shown efficacy in the treatment of newly diagnosed and relapsed light chain (AL) amyloidosis, and is often used in combination with cyclophosphamide and dexamethasone. Ixazomib is the first oral PI to be approved in routine practice but has not yet been evaluated in the upfront treatment setting. Newly diagnosed AL amyloidosis patients with measurable disease and adequate organ function were enrolled. The primary objective was to determine the hematologic response rate of ixazomib in combination with cyclophosphamide and dexamethasone. Treatment was given for 12 cycles, followed by ixazomib maintenance until progression. Thirty-five patients were included; their median age was 67 years, and 69% were male. Major organ involvement included heart (66%) and kidneys (54%). A median of 4 induction cycles (range, 1-12) were administered. The overall hematologic response to induction was 63% and included complete response in 11.4% and very good partial response in 37.1% of patients. One patient was upstaged to complete response during maintenance. The most common reason for going off study was the institution of alternate therapy (61%). With a median follow-up of 29.7 months for the living patients, the 2-year progression-free survival and overall survival were 74% and 78%, respectively. The median time to alternate therapy was 7.5 months. Grade ≥3 hematologic and nonhematologic adverse events occurred in 23% and 49% of patients. Given ixazomib’s favorable toxicity profile, which is an important advantage for the typically frail AL population, further evaluation of ixazomib in other combinations in the upfront setting is warranted. This trial was registered at www.clinicaltrials.gov as #NCT01864018.

TPS7076 Background: Clonal cytopenias of undetermined significance (CCUS) is operationally defined as unexplained persistent cytopenias arising in the context of leukemia-associated somatic driver mutations in hematopoietic stem and progenitor cells, without morphologic evidence for an underlying hematological neoplasm. Patients with TET2 mutant ( TET2MT) CCUS have a high probability of progression to myeloid neoplasms, with approximated 10-year cumulative rates of progression being 90%. To date, no FDA-approved treatment for CCUS has been established, and we have shown that these patients can have transfusion burdens akin to patients with myelodysplastic syndrome (MDS) (Li M et al. Blood Adv 2020). Thus there is an urgent and unmet need for therapies for these patients. Intravenous (IV) ascorbic acid (AA) dosed at pharmacologic concentrations could have anti-cancer activity via two mechanisms: (1) hydrogen peroxide-induced oxidative stress and (2) DNA demethylation mediated by TET activation (cofactor for TET1/2/3). TET2, the primary enzyme for catalyzing oxidative reactions, converts 5-methylcytosine to 5-hydroxymethylcytosine, a crucial step leading to iterative DNA demethylation. Our study hypothesis is that IV AA in TET2MT CCUS will restore hematopoiesis and limit clonal progression by stimulating TET2 (the unmutated allele) and TET3 activities. Methods: LS1781 (NCT03418038) is an investigator-initiated, prospective, single-arm, single-institution, phase II trial assessing the safety and preliminary efficacy of high dose of IV AA for patients with TET2MT CCUS (harboring ≥1 TET2MT or TET2MT combined with concurrent spliceosome MTs). IV AA (1g/kg, maximum 100g) is given 3 times weekly for 12 weeks through a central line with assessments being carried out before each cycle (4 weeks), at 12 weeks, and one year. The primary endpoint is the hematologic response rates determined by MDS IWG 2018 criteria. Secondary endpoints include safety and side effects. Exploratory endpoints include the impact of AA on TET2MT variant allele fraction, plasma cytokine levels, DNA methylation, and hydroxymethylation (as measured by Infinium MethylationEPIC array), and TET activity. Patients 18 years or older with TET2MT CCUS, and with any of the following laboratory criteria: (1) hemoglobin ≤10g/dL, (2) absolute neutrophil count (ANC) ≤1000/mm3, (3) platelet count ≤100,000/mm3 are eligible. Fifteen patients will be enrolled at Mayo Clinic Rochester and the Mayo Clinic Health System. Dose modifications have been established and will be considered based on adverse events. Treatment will be discontinued for disease progression or in the event of ≥Grade 3 adverse events that don’t resolve promptly. Enrollment to the trial began in June 2021, with 7 patients enrolled at abstract submission. Clinical trial information: NCT03418038.

Abstract Therapeutic strategies that target novel pathways are urgently needed for patients with relapsed/refractory multiple myeloma (RRMM). Ibrutinib is an oral covalent inhibitor of Bruton tyrosine kinase, which is overexpressed in MM cells. This phase 1 dose‐escalation study examined various doses of ibrutinib in combination with standard doses of lenalidomide (25 mg) and dexamethasone (40 mg) using a standard 3 + 3 design in RRMM patients. The primary objective was to determine the maximum tolerated dose (MTD) of ibrutinib in combination with lenalidomide and dexamethasone. Patients ( n = 15) had received a median of 4 prior regimens, 53% were triple‐class exposed, 33% were penta‐exposed, and 54% were lenalidomide‐refractory. The MTD of ibrutinib was 840 mg ( n = 6) and only 1 dose‐limiting toxicity; a grade 3 rash possibly related to ibrutinib was noted. The most common ≥ grade 3 adverse events were rash in 2 (13%), lymphopenia in 2 (13%), leukopenia, neutropenia, thrombocytopenia, and anemia all occurring in 3 (20%) patients each. One patient achieved a partial response for an overall response rate of 7%. The clinical benefit rate was 80%. The median time to progression was 3.8 months. Ibrutinib, lenalidomide and dexamethasone appears to be a safe and well‐tolerated regimen with reasonable efficacy in heavily pretreated RRMM patients.

Abstract Introduction: Novel genetic classifications of diffuse large B-cell lymphoma (DLBCL) highlight the molecular complexity beyond cell of origin and provide new therapeutic implications. Next generation trials may incorporate novel agents for different genetic subtypes based on the pathogenesis mechanisms. For example, with the LymphGen classification, the MCD, BN2, ST2, and EZB subtypes are predicted to be susceptive to PI3K/mTOR targeting (Wright 2020). However, PI3K inhibitors have not been tested in the frontline, although data on the mTOR inhibitor everolimus were encouraging (Alliance 1085). We launched a phase 1/1b trial (NCT04323956) to investigate the feasibility of combining a novel PI3K inhibitor parsaclisib with standard R-CHOP immunochemotherapy and to seek an efficacy signal. Methods: Adult patients with newly diagnosed DLBCL were eligible if any of the following was present: 1) non-GCB subtype per the Hans algorithm; 2) expression of either Myc (≥40%) or Bcl2 (≥50%) by immunohistochemistry; or 3) MYC rearrangement by FISH. High grade B-cell lymphoma with MYC and BCL2 and/or BCL6 rearrangements, regardless of morphology, was also eligible. All patients received parsaclisib plus R-CHOP. Phase 1 followed a 3+3 design and the primary endpoint was maximum tolerated dose (MTD) of parsaclisib. Dose levels tested were level 1 (20 mg QD, d1-10; starting level) and level 2 (20 mg QD, d1-14). MTD was defined as the dose level below the lowest dose that induced dose limiting toxicity (DLT) in at least one-third of patients. The primary endpoint in phase 1b is complete response (CR) rate by PET. Results: From July 2020 to June 2021, 15 patients were enrolled, 9 in phase 1 and 6 in phase 1b. The median age at diagnosis was 56 years (range 20-79), and 7 (47%) were female. One patient (7%) had ECOG PS ≥2, 7 (47%) had elevated LDH, 7 (47%) had >1 extranodal site, 13 (87%) had stage III/IV, and 7 (47%) had high-intermediate or high risk International Prognostic Index. Pathology was DLBCL in 13 patients (2 with concurrent follicular lymphoma) and high grade B-cell lymphoma with MYC and BCL2 and/or BCL6 rearrangements in 2 patients. Four (27%) had non-GCB subtype, 7 (47%) had Myc or Bcl2 single expression, 8 (53%) had Myc/Bcl2 double expression, and 5 (33%) had MYC rearrangement (2 with concurrent BCL2 and/or BCL6 rearrangements). In phase 1, 3 patients were enrolled at dose level 1 and 6 patients were enrolled at dose level 2. No DLT was observed. Therefore, MTD was not reached, and dose level 2 was selected for phase 1b dose expansion. Six patients were enrolled in phase 1b to date. At the data cutoff date of 7/22/2021, 8 patients completed all 6 cycles of treatment, 1 competed 5 cycles, 3 completed 3 cycles, 2 completed 2 cycles, and 1 completed 1 cycle. Treatment-related adverse events (AE) are summarized in Table 1. The most common hematological AE included lymphopenia (60%), anemia (53%), neutropenia (53%), and thrombocytopenia (27%), and the most common non-hematological AE included nausea (67%), alopecia (40%), constipation (33%), fatigue (33%), dyspepsia (20%), and peripheral sensory neuropathy (20%). The most common grade 3 or 4 AE included lymphopenia (47%), neutropenia (33%), and anemia (13%). One 80-year-old female required parsaclisib dose reduction in cycle 3 and subsequent parsaclisib discontinuation as well as cyclophosphamide and doxorubicin dose reductions due to febrile neutropenia (no source of infection was identified). No other patients required dose reductions. The median follow-up was 3.7 months (range 0.8-10.7). Thirteen patients were evaluable for interim response by PET. The objective response rate was 92%, with 8 (62%) CR and 4 (31%) partial response (PR). One (8%) patient progressed before cycle 2 following a transient clinical response (shrinking palpable mass). Among those who achieved an objective response at interim, 7 patients were evaluable for end of treatment response and all 7 maintained a response, with 6 (86%) CR and 1 (14%) PR. Conclusions: Parsaclisib and R-CHOP combination therapy was generally well tolerated, with no DLT observed in phase 1 and no major safety concerns in both phase 1 and the ongoing phase 1b expansion. The preliminary efficacy signal of objective response appears encouraging in a small cohort of high risk patients. Parsaclisib plus R-CHOP can be an experimental arm for future frontline DLBCL trials investigating genetic subtype-driven novel therapies. Figure 1 Figure 1. Disclosures Wang: Incyte: Membership on an entity's Board of Directors or advisory committees, Research Funding; InnoCare: Research Funding; LOXO Oncology: Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis: Research Funding; Genentech: Research Funding; MorphoSys: Research Funding; Eli Lilly: Membership on an entity's Board of Directors or advisory committees; TG Therapeutics: Membership on an entity's Board of Directors or advisory committees. King: Celgene/BMS: Research Funding. Ansell: Bristol Myers Squibb, ADC Therapeutics, Seattle Genetics, Regeneron, Affimed, AI Therapeutics, Pfizer, Trillium and Takeda: Research Funding. Tun: Gossamer Bio, Acrotech: Consultancy; Mundipharma, Celgene, BMS, Acrotech, TG therapeutics, Curis, DTRM: Research Funding. Habermann: Seagen: Other: Data Monitoring Committee; Incyte: Other: Scientific Advisory Board; Tess Therapeutics: Other: Data Monitoring Committee; Morphosys: Other: Scientific Advisory Board; Loxo Oncology: Other: Scientific Advisory Board; Eli Lilly & Co.,: Other: Scientific Advisor. Witzig: Karyopharm Therapeutics, Celgene/BMS, Incyte, Epizyme: Consultancy, Membership on an entity's Board of Directors or advisory committees; Celgene/BMS, Acerta Pharma, Kura Oncology, Acrotech Biopharma, Karyopharm Therapeutics: Research Funding. Nowakowski: Celgene, NanoString Technologies, MorphoSys: Research Funding; Celgene, MorphoSys, Genentech, Selvita, Debiopharm Group, Kite/Gilead: Consultancy, Membership on an entity's Board of Directors or advisory committees. OffLabel Disclosure: Parsaclisib is an investigational agent used in this clinical trial.

Abstract Introduction: Central nervous system (CNS) relapse is an uncommon but devastating complication occurring in about 2-10% of patients with diffuse large B-cell lymphoma (DLBCL). The CNS-IPI is a validated prognostic tool used to identify patients at high risk of CNS relapse. MYC and BCL2/BCL6 rearrangements (double-hit lymphoma- DHL) and non-GCB (NGCB) cell of origin may be at higher risk of CNS relapse. However, the ability of these molecular data to refine CNS-IPI risk prediction has not been assessed. In this study, we aimed to describe the impact of DHL and NGCB cell of origin in the incidence of CNS relapse in patients with newly diagnosed DLBCL. Methods: A retrospective review was conducted to identify patients with newly diagnosed DLBCL from 01/01/2002 - 06/30/2015 using the University of Iowa/Mayo Clinic Lymphoma Molecular Epidemiology Resource database. Patients with primary CNS lymphoma or with CNS involvement at diagnosis were excluded. All patients received chemoimmunotherapy. Clinical, biological, laboratory and radiological data were abstracted including the occurrence of CNS relapse. CNS IPI risk score categories were defined as low- (≤1) intermediate- (2-3) and high-risk (≥4) as originally described (Schmitz et al, JCO 2016). Cell of origin (COO) classification into GCB and non-GCB subtypes was performed using Hans algorithm and/or NanoString data. Characteristics between groups were compared using Kruskal-Wallis or Chi-squared test as appropriate. Survival analysis was performed using Cox proportional hazards model and the Kaplan Meier method. Statistical analysis was performed using SAS version 9.4M5 and R version 4.0.3. Results: We identified a total of 1,360 patients with newly diagnosed DLBCL. Patients had a median age of 62 years (range 18-93 years), were predominantly male (56%), had a performance status <2 (84%), had stage III/IV disease (61%) and an elevated LDH (56%) at diagnosis. Fluorescent in situ hybridization data was present for 65% of patients. Among patients with available data, DHL and NGCG COO represented 2.8% and 36% of the cohort, respectively. CNS IPI high- and intermediate-risk categories were present in 12.4% and 52% of the patients, respectively. R-CHOP was the most common upfront chemotherapy (n=980, 72%). The median follow-up for the entire cohort was 84.9 months (IQR: 58.9-120.9). Overall, 50 patients (3.6%) had a CNS relapse during the study period. Lymphoma relapsed in the CNS in 3.0% (95% CI:2.1-4.4), 4.7% (95% CI: 3.4-6.3) and 4.9% (95% CI: 3.7-6.6)% of patients with CNS-IPI score of intermediate/high risk at 1, 3 and 5 years following the diagnosis of DLBCL. In patients with low risk CNS-IPI, 1.1% (95% CI: 0.4-2.5), 1.7% (95% CI: 0.9-3.4) and 1.7% (95% CI: 0.9-3.4) had a CNS relapse at 1, 3 and 5 years following DLBC diagnosis. Patients with CNS relapse were more likely to have elevated LDH (76% vs 56%, p=0.008), advanced stage (78% vs 61%, p=0.01), adrenal involvement (8% vs 2.4%, p=0.014) and have a CNS IPI intermediate risk (68% vs 51%), and high risk (16% vs 12.3%, p=0.014) at the time of initial diagnosis compared to patients without CNS relapse. Patients with CNS relapse had similar rates of DHL (4% vs 2.7%, p=0.17) and NGCB cell of origin (42% vs 36.2%, p=0.52) compared to patients without CNS relapse. In the multivariable analysis, the strongest predictors for CNS relapse were CNS IPI high risk (Hazard Ratio [HR]= 3.6, 95%CI= 1.4-9.7) and CNS IPI intermediate risk (HR= 3.15, 95%CI= 1.46-6.81). DHL and NGCB cell of origin were not associated with a significantly higher risk of CNS relapse (HR= 1.79, [95%CI=0.42-7.59] and HR= 1.26, [95%CI=0.62-2.57], respectively). Conclusion: CNS relapse was an uncommon occurrence in patients with DLBCL who were treated with chemoimmunotherapy. CNS IPI intermediate- and high-risk scores remain the strongest predictors of CNS relapse in patients with DLBCL after adjusting to biological high-risk variables including DHL and NGCB cell of origin. Larger studies are required to validate our findings due to the low incidence of CNS relapse in our cohort. Figure 1 Figure 1. Disclosures Farooq: Kite, a Gilead Company: Honoraria. Maurer: Kite Pharma: Membership on an entity's Board of Directors or advisory committees; Morphosys: Membership on an entity's Board of Directors or advisory committees, Research Funding; Celgene: Research Funding; Genentech: Research Funding; Pfizer: Consultancy, Membership on an entity's Board of Directors or advisory committees; Nanostring: Research Funding. Witzig: Karyopharm Therapeutics, Celgene/BMS, Incyte, Epizyme: Consultancy, Membership on an entity's Board of Directors or advisory committees; Celgene/BMS, Acerta Pharma, Kura Oncology, Acrotech Biopharma, Karyopharm Therapeutics: Research Funding. Habermann: Tess Therapeutics: Other: Data Monitoring Committee; Seagen: Other: Data Monitoring Committee; Incyte: Other: Scientific Advisory Board; Morphosys: Other: Scientific Advisory Board; Loxo Oncology: Other: Scientific Advisory Board; Eli Lilly & Co.,: Other: Scientific Advisor. Novak: Celgene/BMS: Research Funding.

Abstract Introduction: Up to 40% of newly diagnosed diffuse large B cell lymphoma (DLBCL) will relapse after frontline rituximab, doxorubicin, cyclophosphamide, vincristine, and prednisone (RCHOP), with subsequent poor prognosis. Identification of patients (pts) at high risk of relapse early in the treatment can allow for development of risk adapted therapies to improve outcomes. Positron Emission Tomography scan after 2 cycles of therapy (PET2) has been evaluated as a predictor of relapse but study treatments were heterogenous and results were conflicting. A substudy of CALGB 50303 trial did not find association of PET2 response by Deauville Score (DS) with survival in RCHOP and DA-EPOCH-R treated pts. In the UK National Cancer Research Institute Prospective Study, DS of 5 on PET2 predicted worse progression free survival but not overall survival (OS) in RCHOP-21 and RCHOP-14 treated pts. Here we report impact of PET2 response on outcomes in two large independent, prospective cohorts of newly diagnosed DLBCL treated homogenously with two RCHOP-based regimens of similar efficacy. Methods: Discovery was done in adult pts with DLBCL enrolled into a single arm phase 2 trial of lenalidomide plus standard RCHOP (R2CHOP) (MC078E, NCT00670358). The validation cohort comprised of adult pts with newly diagnosed DLBCL treated with standard RCHOP prospectively enrolled into the Mayo component of the University of Iowa/Mayo Clinic Molecular Epidemiology Resource (MER). Both MC078E and MER cohorts included patients who received at least 3-6 cycles of therapy and had a PET2. Pts who progressed on PET2 were excluded. End of treatment (EOT) PET was done 3-12 weeks after last cycle of therapy. The revised response criteria for malignant lymphoma (Cheson, et al 2007) was used to assess PET in MC078E. In MER, revised response criteria for malignant lymphoma (Cheson et al 2007) or Lugano classification was used, depending on era of diagnosis. Positive PET was defined as FDG uptake above background (Cheson 2007) or DS 4 or 5 (Lugano 2014). Study endpoints were event-free survival (EFS) and OS by PET2 status. Results: Out of 118 pts treated on MC078E, 102 had PET2 (MC078E). The median age at diagnosis was 64 years (range 19-87), 61 (60%) were male, 89 (87%) had advanced stage disease, 46 (45%) had international prognostic index (IPI) of 3-5. 58 (57%) were PET2 Negative (PET2-ve) and 44 (43%) were PET2 Positive (PET2+ve). At EOT PET, 83 (81%) had -ve PET and 15 (15%) had +ve PET. Out of 44 PET2+ve pts, 15 remained +ve at EOT PET. Out of 58 PET2-ve pts, 56 had EOT PET available and all were -ve. Out of 866 DLBCL pts enrolled into MER between August 2005 and June 2015, 621 were treated with RCHOP for 3-6 cycles and 272 had available PET2 (MER). The median age was 65 years (range 55-73), 152 (56%) were male, 174 (64%) had advanced stage, 103 (38%) had IPI 3-5. 186 (68%) were PET2-ve and 86 (32%) were PET2+ve. Out of 235 with EOT PET available, 182 (77%) had -ve EOT PET and 25 (11%) had +ve EOT PET. PET2+ve pts had higher odds of +ve EOT PET (OR: 17.4 (CI 95 8.3-40.0), p<0.001) and progression on EOT PET (OR: 4.3 (CI 95 1.9-10.2), p<0.001) in MER cohort. This analysis was not possible on MC078E as all PET2-ve had -ve EOT PET. In MC078E, 2-year EFS and OS were 69.5% (CI 95 61.1-79.1) and 88.1% (CI 95 82-94.7). In MER, 2-year EFS and OS were 71.6% (CI 95 67.7-76.8) and 82.3% (CI 95 79.3-85.3). Compared to PET2-ve, PET2+ve pts had significantly inferior EFS in both MC078E (HR 4.0, CI 95 2.1-7.88, p<0.0001, figure 1a) and MER (HR 2.9, CI 95 1.9-4.1, p<0.0001, figure 1c). Compared to PET2-ve , PET2+ve pts had a trend towards lower OS in MC078E (HR 2.0, CI 95 0.9-4.9, p=0.1, figure 1b) and a significantly lower OS in MER (HR 2.3, CI 95: 1.5-3.4, p<0.0001, figure 1d). In subgroup analysis of MC078E, PET2+ve pts had lower EFS and a trend towards lower OS in all subgroups except IPI 0-2 (Table 1). In MER, PET2+ve pts had lower EFS and OS in all the subgroups except stage I-II and IPI 0-2 (Table 1). Conclusions: Positive PET2 was associated with increased risk of disease progression and death in newly diagnosed DLBCL. Results of our study provide robust evidence of importance of PET2 as an early predictor DLBCL pts at high risk of progression in two independent prospective cohorts. PET2-guided risk-adapted strategies using chimeric antigen receptor T-cell therapy and bispecific antibodies may potentially improve outcomes, should be explored in clinical trials and results of our study serve as a benchmark for such studies. Figure 1 Figure 1. Disclosures Maurer: Kite Pharma: Membership on an entity's Board of Directors or advisory committees; Genentech: Research Funding; Morphosys: Membership on an entity's Board of Directors or advisory committees, Research Funding; Nanostring: Research Funding; Celgene: Research Funding; Pfizer: Consultancy, Membership on an entity's Board of Directors or advisory committees. Wang: Genentech: Research Funding; Eli Lilly: Membership on an entity's Board of Directors or advisory committees; Novartis: Research Funding; MorphoSys: Research Funding; InnoCare: Research Funding; Incyte: Membership on an entity's Board of Directors or advisory committees, Research Funding; LOXO Oncology: Membership on an entity's Board of Directors or advisory committees, Research Funding; TG Therapeutics: Membership on an entity's Board of Directors or advisory committees. Cerhan: Celgene/BMS: Other: Connect Lymphoma Scientific Steering Committee, Research Funding; Regeneron Genetics Center: Other: Research Collaboration; NanoString: Research Funding; Genentech: Research Funding. Ansell: Bristol Myers Squibb, ADC Therapeutics, Seattle Genetics, Regeneron, Affimed, AI Therapeutics, Pfizer, Trillium and Takeda: Research Funding. Habermann: Seagen: Other: Data Monitoring Committee; Incyte: Other: Scientific Advisory Board; Tess Therapeutics: Other: Data Monitoring Committee; Morphosys: Other: Scientific Advisory Board; Loxo Oncology: Other: Scientific Advisory Board; Eli Lilly & Co.,: Other: Scientific Advisor. Witzig: Celgene/BMS, Acerta Pharma, Kura Oncology, Acrotech Biopharma, Karyopharm Therapeutics: Research Funding; Karyopharm Therapeutics, Celgene/BMS, Incyte, Epizyme: Consultancy, Membership on an entity's Board of Directors or advisory committees. Nowakowski: Celgene, NanoString Technologies, MorphoSys: Research Funding; Celgene, MorphoSys, Genentech, Selvita, Debiopharm Group, Kite/Gilead: Consultancy, Membership on an entity's Board of Directors or advisory committees.

Background: Bortezomib, a proteasome inhibitor, has shown efficacy in the treatment of newly diagnosed and relapsed light chain (AL) amyloidosis, and the combination of bortezomib, cyclophosphamide and dexamethasone is a commonly used regimen in AL. Ixazomib is the first oral proteasome inhibitor to be approved, and the combination of ixazomib with cyclophosphamide and dexamethasone is an all oral effective regimen for the treatment of multiple myeloma. This phase 2 trial was designed to evaluate the efficacy of this regimen in patients with AL, who have not received any therapy. Patients and methods: Newly diagnosed patients with biopsy proven AL amyloidosis, with organ involvement requiring therapy, were enrolled if they had measurable disease (Serum immunoglobulin free light chain ≥5 mg/dL AND abnormal serum free light chain ratio) and adequate organ function. Patients with severe organ involvement were excluded (Alkaline phosphatase >750 U/L, creatinine clearance <30 mL/min or NT-ProBNP ≥ 7500 ng/dL). Treatment consisted of ixazomib 4 mg days 1, 8, 15; cyclophosphamide 500 mg PO weekly and dexamethasone 40 mg, weekly for twelve 28-day cycles, followed by ixazomib maintenance (days 1, 8, 15) at the last tolerated dose till progression. The primary objective was to determine the hematologic response rate of ixazomib, used in combination with cyclophosphamide and dexamethasone in patients with previously untreated AL. A one-stage binomial design was utilized to test the null hypothesis that the hematologic response rate is at most 30% against the alternative hypothesis that it is at least 50%, with 85% power and 9% type I error. Results: Thirty-five patients were enrolled, median age was 67 (range 38-78) years; 69% were male. Organ involvement included cardiac in 23 (65.7%), renal in 19 (54.3%), and nervous system involvement in 5 (14.3%). At data cutoff 8 patients still remain on study with a median follow up of 4.4 months for those who are alive. Across the trial a median of 4 cycles (range 0-23) of treatment have been completed; the most common reason for going off study was institution of alternate therapy in 17 patients (63%). The overall hematologic response was 57% (20/35) and included amyloid CR in 5 (14%), VGPR in 9 (26%) and a PR in 6 (17%) patients. Confirmed organ responses have been observed in 5 patients so far, 2 each for cardiac and renal and 1 hepatic. The median PFS and OS have not been reached; 4 patients had hematological progression; 6 patients (17%) have died. Across 193 cycles of treatment administered, dose modification was required in 5, 3, and 10 patients, respectively, for ixazomib, cyclophosphamide and dexamethasone. A grade 3 or higher adverse event (AE), at least possibly attributed to the study drugs, was observed in 41% of patients. The figure shows the maximum grade of adverse events for individual patients seen in more than one patient across the study. Conclusions: The all-oral regimen of ixazomib, cyclophosphamide, and dexamethasone is active in patients with previously untreated AL amyloidosis with hematologic responses observed in 57% of patients, including complete responses. Organ response has been observed but will likely need longer follow up for accurate assessment, given the delay in organ responses in this disease. Further evaluation of this combination is warranted. Disclosures Gertz: Alnylam: Consultancy; Ionis/Akcea: Consultancy; Amgen: Consultancy; Medscape: Consultancy, Speakers Bureau; Physicians Education Resource: Consultancy; Data Safety Monitoring board from Abbvie: Membership on an entity's Board of Directors or advisory committees; Celgene: Consultancy; Johnson and Johnson: Speakers Bureau; DAVA oncology: Speakers Bureau; Advisory Board for Pharmacyclics: Membership on an entity's Board of Directors or advisory committees; Advisory Board for Proclara: Membership on an entity's Board of Directors or advisory committees; i3Health: Consultancy; Springer Publishing: Patents & Royalties; Amyloidosis Foundation: Research Funding; International Waldenstrom Foundation: Research Funding; NCI SPORE MM: Research Funding; Prothena: Consultancy; Sanofi: Consultancy; Janssen: Consultancy; Spectrum: Consultancy, Research Funding; Annexon: Consultancy; Appellis: Consultancy. Kapoor:Celgene: Honoraria; GlaxoSmithKline: Research Funding; Takeda: Honoraria, Research Funding; Amgen: Research Funding; Sanofi: Consultancy, Research Funding; Janssen: Research Funding; Cellectar: Consultancy. Larsen:Janssen Oncology: Honoraria, Membership on an entity's Board of Directors or advisory committees; Takeda: Honoraria, Membership on an entity's Board of Directors or advisory committees. Dingli:Apellis: Consultancy; Janssen: Consultancy; Sanofi-Genzyme: Consultancy; Rigel: Consultancy; Bristol Myers Squibb: Research Funding; Karyopharm Therapeutics: Research Funding; Alexion: Consultancy; Millenium: Consultancy. Dispenzieri:Janssen: Research Funding; Intellia: Research Funding; Alnylam: Research Funding; Celgene: Research Funding; Pfizer: Research Funding; Takeda: Research Funding. Kumar:Adaptive Biotechnologies: Consultancy; Carsgen: Other, Research Funding; AbbVie: Other: Research funding for clinical trials to the institution, Consulting/Advisory Board participation with no personal payments; Janssen Oncology: Other: Research funding for clinical trials to the institution, Consulting/Advisory Board participation with no personal payments; Genecentrix: Consultancy; Dr. Reddy's Laboratories: Honoraria; Tenebio: Other, Research Funding; Takeda: Other: Research funding for clinical trials to the institution, Consulting/Advisory Board participation with no personal payments; BMS: Consultancy, Research Funding; Sanofi: Research Funding; Novartis: Research Funding; Kite Pharma: Consultancy, Research Funding; Karyopharm: Consultancy; Oncopeptides: Consultancy, Other: Independent Review Committee; IRC member; Merck: Consultancy, Research Funding; Amgen: Consultancy, Other: Research funding for clinical trials to the institution, Consulting/Advisory Board participation with no personal payments, Research Funding; Genentech/Roche: Other: Research funding for clinical trials to the institution, Consulting/Advisory Board participation with no personal payments; Celgene/BMS: Other: Research funding for clinical trials to the institution, Consulting/Advisory Board participation with no personal payments; Cellectar: Other; MedImmune: Research Funding.

Background: The combination of a proteasome inhibitor (PI), an immunomodulatory drug (IMiD), and dexamethasone is the current standard induction therapy for myeloma. Daratumumab (Dara), a monoclonal antibody directed against CD38, is highly effective in treating myeloma and improves response rates and progression free survival (PFS) when added to PI or IMiD. Ixazomib, lenalidomide and dexamethasone (IRd) is an effective, all oral, induction regimen that has been studied in phase 2 and 3 trials. We designed this trial to examine the feasibility and efficacy of adding daratumumab to the IRd regimen as well as early discontinuation of dexamethasone in two sequential cohorts of patients. Patients and Methods: Patients with previously untreated MM who had measurable disease and adequate organ function were enrolled, irrespective of their autologous stem cell transplant eligibility. The primary objective was to determine the rate of complete response to IRD-Dara combination. A one-stage binomial design was utilized in each cohort independently to test the null hypothesis that the complete response rate is at most 25% against the alternative hypothesis that it is at least 45%, with 89% power and 9% type I error. Treatment involved 28-day cycles consisting of ixazomib 4 mg days 1, 8, 15; lenalidomide 25 mg days 1-21, dexamethasone 40 mg, weekly and Dara 16 mg/kg, weekly for two cycles, every other week during cycles 3-6 and then every 4 weeks thereafter during induction (12-cyles) followed by Dara-ixazomib maintenance (maximum 24 cycles). Cohorts A (n=38) and B (N=40) comprised the study population, with dexamethasone discontinued after two cycles in Cohort B. Results: Baseline demographics and patient disposition are outlined in the table. Among those who have gone off study, 9 and 5 patients, respectively in Cohort A and B went off for progression, while 11 and 8 patients in the respective arms discontinued treatment for an alternative therapy, most frequently a transplant. Responses were rapid and deepened over the duration of treatment as shown in the figure; 32% of patients in Cohort A and 28% of patients in Cohort B achieved a complete response; 29% and 23%, respectively, achieved a marrow minimal residual disease (MRD) negative status. After a median follow up was 31.4 months for Cohort A and 18.2 months for Cohort B, median PFS has not been reached in either cohort. A grade 3 or higher adverse event at least possibly attributed to the study drugs was seen in 58% of patients in Cohort A (hematologic in 47% and non-hematologic in 26%) and 50% of patients in Cohort B (hematologic 43%, non-hematologic 20%). The most common toxicities included fatigue, neutropenia, lymphopenia, peripheral neuropathy and nausea. Stem cells were collected in 30 and 31 patients in Cohorts A and B respectively; median (range) of CD34 cells/kg were 8.5 (2.8, 15.9) x 106and 7.0 (2.9, 12.1) x 106, with plerixafor used in 83% and 94% of patients, respectively, in Cohorts A and B as per our standard of care "on-demand" approach based on blood CD34 count. Conclusion: Dara-IRd is an active regimen in newly diagnosed MM, with high overall rates of response and deep responses that improved over time with therapy. Early discontinuation of dexamethasone does not appear to impact the depth, rate or kinetics of response. The toxicities were manageable, with dose modifications. All patients were able to collect stem cells when required, though majority needed plerixafor. Disclosures Kumar: Amgen: Consultancy, Other: Research funding for clinical trials to the institution, Consulting/Advisory Board participation with no personal payments, Research Funding; Kite Pharma: Consultancy, Research Funding; Carsgen: Other, Research Funding; Janssen Oncology: Other: Research funding for clinical trials to the institution, Consulting/Advisory Board participation with no personal payments; Cellectar: Other; Dr. Reddy's Laboratories: Honoraria; Takeda: Other: Research funding for clinical trials to the institution, Consulting/Advisory Board participation with no personal payments; AbbVie: Other: Research funding for clinical trials to the institution, Consulting/Advisory Board participation with no personal payments; Celgene/BMS: Other: Research funding for clinical trials to the institution, Consulting/Advisory Board participation with no personal payments; Merck: Consultancy, Research Funding; Adaptive Biotechnologies: Consultancy; Tenebio: Other, Research Funding; Oncopeptides: Consultancy, Other: Independent Review Committee; IRC member; Genentech/Roche: Other: Research funding for clinical trials to the institution, Consulting/Advisory Board participation with no personal payments; Genecentrix: Consultancy; Sanofi: Research Funding; Novartis: Research Funding; MedImmune: Research Funding; Karyopharm: Consultancy; BMS: Consultancy, Research Funding. Kapoor:GlaxoSmithKline: Research Funding; Celgene: Honoraria; Takeda: Honoraria, Research Funding; Amgen: Research Funding; Sanofi: Consultancy, Research Funding; Janssen: Research Funding; Cellectar: Consultancy. Dingli:Apellis: Consultancy; Karyopharm Therapeutics: Research Funding; Janssen: Consultancy; Bristol Myers Squibb: Research Funding; Alexion: Consultancy; Rigel: Consultancy; Millenium: Consultancy; Sanofi-Genzyme: Consultancy. Dispenzieri:Pfizer: Research Funding; Takeda: Research Funding; Alnylam: Research Funding; Janssen: Research Funding; Celgene: Research Funding; Intellia: Research Funding. Gertz:Abbvie: Other; Sanofi: Other; Celgene: Other; Research to Practice: Other; Physicians Education Resource: Other: personal fee; Amgen: Other: personal fee; Medscape: Other: personal fee, Speakers Bureau; Appellis: Other: personal fee; Annexon: Other: personal fee; Alnylam: Other: personal fee; Spectrum: Other: personal fee, Research Funding; Janssen: Other: personal fee; Teva: Speakers Bureau; Aurora Bio: Other; Springer Publishing: Patents & Royalties; Proclara: Other; DAVA oncology: Speakers Bureau; Johnson and Johnson: Speakers Bureau; Ionis/Akcea: Other: personal fee; Prothena: Other: personal fee.