Lacy, Martha Q.

Abstract Comparative data guiding initial therapy for Waldenström macroglobulinemia (WM), an infrequently encountered non‐Hodgkin lymphoma, are sparse. We evaluated three commonly used rituximab‐based frontline regimens: rituximab‐bendamustine (R‐Benda); dexamethasone, rituximab, cyclophosphamide (DRC); and bortezomib, dexamethasone, rituximab (BDR) in 220 treatment‐naïve patients with WM, seen at Mayo Clinic between November 1, 2000 and October 31, 2019. The median follow‐up was 4.5 (95%CI: 4–5) years. The R‐Benda cohort (n = 83) demonstrated superior overall response rate (ORR: 98%), in comparison to DRC (n = 92, ORR: 78%) or BDR (n = 45, ORR: 84%) cohorts, p = 0.003. Similarly, longer progression‐free survival (PFS) was evident with R‐Benda use [median 5.2 vs. 4.3 (DRC) and 1.8 years (BDR), p < 0.001]. The time‐to‐next therapy (TTNT) favored R‐Benda [median, not‐reached, 4.4 (DRC) and 2.6 years (BDR), p < 0.001). These endpoints were comparable between the DRC and BDR cohorts. Overall survival (OS) was similar across the three cohorts, p = 0.77. In a subset analysis of 142 patients genotyped for MYD88 L265P mutation, the ORR, PFS and TTNT were unaffected by the patients' MYD88 signature within each cohort. In conclusion, ORR, PFS and TTNT with R‐Benda are superior compared to DRC or BDR in treatment‐naïve patients with active WM. The patient outcomes with any one of these three regimens are unaffected by the MYD88 L265P mutation status.

Abstract The utility of systemic light chain (AL) amyloidosis staging systems has been validated for newly diagnosed patients, but their role in restaging after treatment has not been explored. We designed this study to evaluate whether the currently used systems are of prognostic value at 3 and 6 months of starting first-line treatment, and whether stage migration from diagnosis impacts survival. This is a retrospective study including Mayo Clinic patients with AL amyloidosis diagnosed between 1 January 2006 and 30 June 2019; 536 and 204 patients had restaging data for at least 1 system at 3 and 6 months, respectively. Using modified Mayo 2004 staging at 3 months, median overall survival (OSs) were 11.8, 10.8, 4.6, and 1.1 years for stage I, II, IIIa, and IIIb, respectively. Using Mayo 2012, median OSs were 11.8, 9.0, 5.2, and 0.8 years for stage I, II, III, and IV, respectively. Using modified Mayo 2004 staging at 6 months, median OSs were not reached (NR), NR, 5.4, and 0.9 years for stage I, II, IIIa, and IIIb, respectively. Using Mayo 2012, OSs were NR, NR, 4.6, and 0.9 years for stage I, II, III, and IV, respectively. Worsening stage at 3 or 6 months was associated with worse survival than retaining baseline stage. In conclusion, the current staging systems can be used for restaging at 3 and 6 months from treatment initiation. Migration to higher stage predicts poor prognosis.

Introduction: Cardiac involvement is one of the main predictors for survival in patients with light chain (AL) amyloidosis. Biomarkers such as Troponin T and N-terminal pro b-type natriuretic peptide (NT-proBNP) are used routinely for detecting cardiac involvement. In addition echocardiogram (ECHO) is used to determine septal and left ventricular wall thickness and strain. Most patients with AL present with preserved ejection fraction (EF) however, the outcomes of AL patients undergoing autologous stem cell transplantation (ASCT) with decreased EF are not very well described. Methods: We retrospectively reviewed patients who had a diagnosis of AL amyloidosis and received ASCT between March 1996 and September 2017. All patients had an ECHO done before ASCT and the EF was documented. In our practice, the threshold for performing ASCT is an EF &gt;40%. We evaluated the outcomes of patients who had an EF &lt;55% compared to patients with an EF ≥55%. The baseline characteristics were compared between patients with high and low EF. Progression-free survival (PFS) was defined as time from ASCT to disease progression, relapse, or death of any cause. Overall survival (OS) was calculated from time of ASCT to death of any cause. Univariate and multivariate analysis for PFS and OS were done using the following variables: age&gt;65 vs. ≤65 years, Mayo 2012 stage 3/4 vs. 1/2, bone marrow plasma cell percentage (BMPC) ≥ 10% vs. &lt;10%, organs involved &gt;2 vs. ≤2, melphalan conditioning 200mg/m2 vs. 140 mg/m2 ,ASCT year &gt;2010 vs. ≤2010, and EF &lt;55% vs. ≥55%. Results: We identified 716 patients and 69 (10%) had an EF&lt;55%, with most (n=63, 91%)having cardiac involvement . Compared to patients with EF ≥55%, patients with EF &lt;55% were more likely to have Mayo 2012 stage 3/4 (58% vs. 22%, P&lt;0.0001) and more likely to have thicker interventricular septum (median 14 vs. 12 mm, P&lt;0.0001). The day 100 transplant related mortality (TRM) was higher in patients with EF &lt;55% compared to EF ≥55% (19% vs. 6%, P=0.0006). In patients with Mayo 2012 stage 3/4, the day 100 TRM was higher in patients with an EF&lt;55% compared to EF ≥55% (27% vs. 7%, P=0.004). Overall, PFS and OS were significantly shorter in patients with EF &lt;55% compared to patients with EF ≥55% (Figure 1 A,B). Evaluating PFS and OS according to EF specifically in Mayo 2012 stage 3/4 patients is displayed in Figure 1 (C,D). Predictors for PFS included Mayo 2012 stage 3/4 vs. 1/2 (hazard ratio (HR): 1.4, P=0.006), BMPC ≥ 10% vs. &lt;10% (HR: 1.5,P=0.0005), melphalan conditioning 200mg/m2 vs. 140 mg/m2 (HR:0.7, P=0.01), ASCT year &gt;2010 vs. ≤2010 (HR: 0.7, P=0.01), and EF &lt;55% vs. ≥55% (HR: 1.5, P=0.02). For OS, age &gt;65 vs. ≤65 years (HR:1.4, P=0.04), Mayo 2012 stage 3/4 vs. 1/2 (HR: 1.96, P&lt;0.0001), melphalan conditioning 200mg/m2 vs. 140 mg/m2 (HR:0.5, P&lt;0.0001), BMPC ≥ 10% vs. &lt;10% (HR: 1.8, P=0.03), ASCT year &gt;2010 vs. ≤2010 (HR: 0.5, P&lt;0.0001), and EF &lt;55% vs. ≥55%(HR:1.9, P=0.003) were predictive. Conclusion: Having an EF &lt;55% is associated with a higher day 100 TRM and is an independent predictor for PFS and OS in patients with AL amyloidosis undergoing ASCT. Disclosures Sidiqi: Janssen: Honoraria; Amgen: Honoraria; Celgene: Honoraria, Other: Travel grant. Dingli:Alexion: Consultancy; Apellis: Consultancy; Sanofi-Genzyme: Consultancy; Millenium: Consultancy; Bristol Myers Squibb: Research Funding; Karyopharm Therapeutics: Research Funding; Janssen: Consultancy; Rigel: Consultancy. Kapoor:Janssen: Research Funding; GlaxoSmithKline: Research Funding; Cellectar: Consultancy; Sanofi: Consultancy, Research Funding; Celgene: Honoraria; Takeda: Honoraria, Research Funding; Amgen: Research Funding. Dispenzieri:Janssen: Research Funding; Pfizer: Research Funding; Alnylam: Research Funding; Intellia: Research Funding; Takeda: Research Funding; Celgene: Research Funding. Kumar:AbbVie: Other: Research funding for clinical trials to the institution, Consulting/Advisory Board participation with no personal payments; Takeda: 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; Amgen: Consultancy, Other: Research funding for clinical trials to the institution, Consulting/Advisory Board participation with no personal payments, Research Funding; Merck: Consultancy, Research Funding; Adaptive Biotechnologies: Consultancy; Celgene/BMS: Other: Research funding for clinical trials to the institution, Consulting/Advisory Board participation with no personal payments; Dr. Reddy's Laboratories: Honoraria; Genentech/Roche: Other: Research funding for clinical trials to the institution, Consulting/Advisory Board participation with no personal payments; Oncopeptides: Consultancy, Other: Independent Review Committee; IRC member; Kite Pharma: Consultancy, Research Funding; Novartis: Research Funding; Sanofi: Research Funding; MedImmune: Research Funding; Karyopharm: Consultancy; BMS: Consultancy, Research Funding; Tenebio: Other, Research Funding; Genecentrix: Consultancy; Cellectar: Other; Carsgen: Other, Research Funding. Gertz:Spectrum: Other: personal fee, Research Funding; Janssen: Other: personal fee; Sanofi: Other; Research to Practice: Other; Celgene: Other; Medscape: Other: personal fee, Speakers Bureau; Proclara: Other; DAVA oncology: Speakers Bureau; Alnylam: Other: personal fee; Johnson and Johnson: Speakers Bureau; Physicians Education Resource: Other: personal fee; Teva: Speakers Bureau; Ionis/Akcea: Other: personal fee; Amgen: Other: personal fee; Springer Publishing: Patents & Royalties; Aurora Bio: Other; Appellis: Other: personal fee; Abbvie: Other; Annexon: Other: personal fee; Prothena: Other: personal fee.

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 &gt;750 U/L, creatinine clearance &lt;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: Multiple myeloma (MM) is a heterogeneous disease that may be evaluated by a broad array of imaging and laboratory techniques to measure disease activity and predict prognosis. FDG PET/CT has been shown to be predictive of patient outcomes throughout the disease course, with several studies demonstrating that PET/CT is an independent prognostic factor for progression free survival and overall survival (OS). We sought to corroborate these findings by specifically examining the prognostic impact of PET/CT in the post-transplant setting. We retrospectively analyzed PET/CT in MM patients after consolidation therapy with autologous stem cell transplant (ASCT) and correlated these findings with time to progression (TTP) and OS to assess the impact of day 100 PET/CT findings as an independent prognostic factor. Methods: A retrospective cohort study was conducted on 231 myeloma patients who underwent ASCT between 2003-2016 and had a FDG PET/CT exam available for analysis at an average of day 104 post-transplant. We recorded the findings on PET/CT prior to transplant, where available. PET/CT without evidence of active/residual disease (PET-) was defined per IMWG guidelines (disappearance of every area of increased tracer uptake found on preceding PET/CT, or uptake &lt; mediastinal blood pool, or decrease &lt; surrounding normal tissue). PET/CT indicating active disease (PET+) was defined as any abnormal uptake or incompletely resolved uptake from previous exam. A Kaplan-Meier model was used to estimate median TTP and OS and the 2-sided log-rank test to compare groups. TTP and OS were calculated from the date of ASCT to the date of confirmed disease progression or death, respectively. Outcomes were then compared among patients with a PET/CT versus those without a PET/CT post-ASCT to assess for the presence of selection bias. A proportional hazards fit model was used for multivariate analysis. Results: The median length of follow-up for the entire cohort was 49 months (range: 43-58 mo), median TTP was 18.5 months (95% CI; 15.4-21.8), and median OS was 61.5 months (95% CI; 49-75). Among the entire cohort (n=231), 150 (65%) patients had a positive PET/CT exam at day 100 post-ASCT while 81 (35%) had a negative PET exam. There were 195 (84%) patients with a PET/CT exam prior to ASCT available for comparison, of which 161 (85%) were PET+ and 29 (15%) were PET-. Median time between PET/CT exams was 4.1 months (range 1.4-55). Median TTP among PET+ patients near day 100 was 12.4 months vs. 24 months PET- patients (p&lt;.0001, Fig 1, panel A). Median OS in the PET+ group was 46 months compared to 99 months in the PET- group (p&lt;.0001, Fig 1, panel B). Among patients with a prior PET/CT (195, 84%), median TTP was longer in patients with both exams negative compared to those who were day 100 PET- and previously PET+ (42.6 mo vs. 21.1 mo respectively; p&lt;.0001). TTP was shorter in those who were day 100 PET+ and previously PET- compared to those with persistently PET+ on both exams (4.5 vs. 12.3 mo; p&lt;.0001, Figure 2). Since PET/CT was not routinely ordered post ASCT, we also compared the outcomes between patients getting a PET/CT (n=231) and remaining patients undergoing ASCT (n=1764). Among patients with a day 100 PET/CT vs. those without a PET/CT exam, there was a slightly longer median TTP and OS in the group who did not have a post-ASCT PET/CT. Hazard ratios (HR) after adjusting for disease response (CR at day 100 vs. non-CR) were as follows: TTP PET+ HR 1.76 (1.2-2.4; p=0.003), OS PET+ HR 1.8 (1.2-2.6; p=.0016). Conclusions: MM is a heterogeneous disease that relies on different assessments for determining response, activity, and prognosis. Among these, PET/CT has shown promise in predicting prognosis, independent of disease state and conventional prognostic factors. Our study confirms these findings, demonstrating that an abnormal PET/CT near day 100 post-transplant is predictive of shorter TTP and OS. This prognostic significance remained even after adjusting for disease response (CR vs. non-CR), which could be explained by the sometimes patchy distribution of myeloma in the bone marrow, and identification of extramedullary disease by PET/CT. Taken together, these results demonstrate a possible role for incorporating PET/CT in the post-transplant setting as an independent prognostic variable in stratifying disease risk. Disclosures Dingli: Apellis: Consultancy; Janssen: Consultancy; Rigel: Consultancy; Millenium: Consultancy; Karyopharm Therapeutics: Research Funding; Sanofi-Genzyme: Consultancy; Bristol Myers Squibb: Research Funding; Alexion: Consultancy. Gertz:NCI SPORE MM: Research Funding; International Waldenstrom Foundation: Research Funding; Amyloidosis Foundation: Research Funding; Springer Publishing: Patents & Royalties; i3Health: Consultancy; Advisory Board for Proclara: Membership on an entity's Board of Directors or advisory committees; Advisory Board for Pharmacyclics: Membership on an entity's Board of Directors or advisory committees; DAVA oncology: Speakers Bureau; Johnson and Johnson: Speakers Bureau; Celgene: Consultancy; Data Safety Monitoring board from Abbvie: Membership on an entity's Board of Directors or advisory committees; Physicians Education Resource: Consultancy; Medscape: Consultancy, Speakers Bureau; Amgen: Consultancy; Appellis: Consultancy; Annexon: Consultancy; Spectrum: Consultancy, Research Funding; Janssen: Consultancy; Sanofi: Consultancy; Prothena: Consultancy; Alnylam: Consultancy; Ionis/Akcea: Consultancy. Dispenzieri:Janssen: Research Funding; Celgene: Research Funding; Alnylam: Research Funding; Pfizer: Research Funding; Intellia: Research Funding; Takeda: Research Funding. Kapoor:Takeda: Honoraria, Research Funding; Amgen: Research Funding; Sanofi: Consultancy, Research Funding; Janssen: Research Funding; Celgene: Honoraria; Cellectar: Consultancy; GlaxoSmithKline: Research Funding. Lin:Sorrento: Consultancy, Membership on an entity's Board of Directors or advisory committees; Vineti: Consultancy; Novartis: Consultancy; Celgene: Consultancy, Research Funding; Bluebird Bio: Consultancy, Research Funding; Juno: Consultancy; Legend BioTech: Consultancy; Merck: Research Funding; Takeda: Research Funding; Gamida Cells: Consultancy; Janssen: Consultancy, Research Funding; Kite, a Gilead Company: Consultancy, Research Funding. Kumar:Amgen: Consultancy, Other: Research funding for clinical trials to the institution, Consulting/Advisory Board participation with no personal payments, Research Funding; Merck: Consultancy, Research Funding; Adaptive Biotechnologies: Consultancy; Janssen Oncology: Other: Research funding for clinical trials to the institution, Consulting/Advisory Board participation with no personal payments; Genentech/Roche: Other: Research funding for clinical trials to the institution, Consulting/Advisory Board participation with no personal payments; Dr. Reddy's Laboratories: Honoraria; Novartis: Research Funding; Kite Pharma: Consultancy, Research Funding; Karyopharm: Consultancy; Oncopeptides: Consultancy, Other: Independent Review Committee; IRC member; AbbVie: Other: Research funding for clinical trials to the institution, Consulting/Advisory Board participation with no personal payments; Takeda: Other: Research funding for clinical trials to the institution, Consulting/Advisory Board participation with no personal payments; Cellectar: Other; Tenebio: Other, Research Funding; Sanofi: Research Funding; Celgene/BMS: Other: Research funding for clinical trials to the institution, Consulting/Advisory Board participation with no personal payments; Carsgen: Other, Research Funding; Genecentrix: Consultancy; MedImmune: Research Funding; BMS: Consultancy, Research Funding.

Background: The absence of residual monoclonal protein in the serum and urine by IFE using specific antibodies to individual heavy and light chains has been an important part of response assessment and is required for categorizing patients as in complete response. MASS FIX has been shown to be more sensitive in picking up small amounts of monoclonal protein and represents an advancement in the field. Ongoing studies are examining the clinical significance of this increased sensitivity. We designed the following study using clinically obtained test results to examine this question. Patients and methods: The clinical laboratory at Mayo Clinic changed the process from IFE to MASS FIX in July 2018. We identified patients who had sequential testing before and after this date and collected test results from the last IFE prior to the date of transition and the first MASS FIX after the date of transition. Patients were grouped based on the paired results and outcomes compared between groups. Time to next therapy (TTNT) was defined as the time from the first MASS FIX date to the start of next therapy. Survival was estimated by the Kaplan-Meier method and these curves were compared using log rank test. Results: Overall, 739 patients with MM, who had a MASS FIX within 12 months of the IFE were studied; 380 (51%) patients had a negative IFE prior to implementation of MASS FIX. These patients had a MASS FIX test performed at a median of 3.7 (0.03-12) months from the last available IFE. The gap between IFE and MASS FIX was &lt;6 months and &lt; 3 months in 71% and 54% of the patients. Among the patients with a negative IFE, 130 (34%) tested positive on the subsequent MASS FIX. Limiting the analysis to those with a MASS FIX within 6 and 3 months yielded 32% in each group that turned positive from previous negative IFE. The median TTNT from the MASS FIX date was significantly shorter for those who became positive on MASSFIX; median was not reached for either group (P=0.002) (Figure). We then limited the analysis to those patients with a gap of &lt;6 months and &lt;3 months between the tests. The results were consistent: P= 0.012 for those with a gap of &lt; 6 months and P=0.01 for those with a gap &lt; 3 months. Conclusion: The results suggest that the additional sensitivity offered by MASS FIX have clinical significance in patients with MM, given that patients with residual disease identified by MASS FIX have an earlier relapse. The data supports the use of the more sensitive MASS FIX in the laboratory compared to the conventional IFE approaches. The study has the disadvantage that the samples were not tested simultaneously and some of the samples turning positive may reflect an early evidence of relapse, but the relative consistency of the finding irrespective of the gap between the tests argues against that. Ongoing studies are examining MASS FIX on the samples that were called to be negative by IFE initially. Figure Disclosures Murray: The Binding Site: Patents & Royalties: Patent Use of Mass Spec to identify monoclonal proteins licensed to The Binding Site. Dispenzieri:Takeda: Research Funding; Celgene: Research Funding; Janssen: Research Funding; Intellia: Research Funding; Pfizer: Research Funding; Alnylam: Research Funding. Kapoor:Cellectar: Consultancy; Sanofi: Consultancy, Research Funding; Janssen: Research Funding; Celgene: Honoraria; Takeda: Honoraria, Research Funding; GlaxoSmithKline: Research Funding; Amgen: Research Funding. Gertz:Janssen: Other: personal fee; Spectrum: Other: personal fee, Research Funding; Springer Publishing: Patents & Royalties; Abbvie: Other; Appellis: Other: personal fee; Annexon: Other: personal fee; Celgene: Other; Amgen: Other: personal fee; Physicians Education Resource: Other: personal fee; Medscape: Other: personal fee, Speakers Bureau; Research to Practice: Other; Sanofi: Other; Teva: Speakers Bureau; Johnson and Johnson: Speakers Bureau; DAVA oncology: Speakers Bureau; Proclara: Other; Aurora Bio: Other; Prothena: Other: personal fee; Alnylam: Other: personal fee; Ionis/Akcea: Other: personal fee. Dingli:Karyopharm Therapeutics: Research Funding; Bristol Myers Squibb: Research Funding; Rigel: Consultancy; Sanofi-Genzyme: Consultancy; Millenium: Consultancy; Alexion: Consultancy; Janssen: Consultancy; Apellis: Consultancy. Lin:Janssen: Consultancy, Research Funding; Kite, a Gilead Company: Consultancy, Research Funding; Takeda: Research Funding; Gamida Cells: Consultancy; Sorrento: Consultancy, Membership on an entity's Board of Directors or advisory committees; Vineti: Consultancy; Legend BioTech: Consultancy; Merck: Research Funding; Novartis: Consultancy; Celgene: Consultancy, Research Funding; Bluebird Bio: Consultancy, Research Funding; Juno: Consultancy. Kumar:Dr. Reddy's Laboratories: Honoraria; AbbVie: Other: Research funding for clinical trials to the institution, Consulting/Advisory Board participation with no personal payments; Carsgen: Other, Research Funding; BMS: Consultancy, Research Funding; Karyopharm: Consultancy; Tenebio: Other, Research Funding; Celgene/BMS: Other: Research funding for clinical trials to the institution, Consulting/Advisory Board participation with no personal payments; Adaptive Biotechnologies: Consultancy; Kite Pharma: Consultancy, Research Funding; Sanofi: Research Funding; Takeda: 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; Genentech/Roche: Other: Research funding for clinical trials to the institution, Consulting/Advisory Board participation with no personal payments; Merck: Consultancy, Research Funding; MedImmune: Research Funding; Cellectar: Other; Genecentrix: Consultancy; Oncopeptides: Consultancy, Other: Independent Review Committee; IRC member; Amgen: Consultancy, Other: Research funding for clinical trials to the institution, Consulting/Advisory Board participation with no personal payments, Research Funding; Novartis: Research Funding.

Background: Multiple myeloma is typically characterized by clonal expansion of malignant plasma cells within the bone marrow compartment. Presence of extramedullary disease (EMD) either in the form of soft tissue plasmacytoma or circulating plasma cells can be seen at diagnosis but is more common in the relapsed and refractory patients. Presence of EMD is typically associated with a poor prognosis, both in the newly diagnosed and relapsed setting, but trials designed specifically for patients with EMD are sparse. Treatment of EMD can be challenging and the responses even when seen are often short lasting, highlighting the need for developing specific treatment approaches aimed at these patients. Based on initial trials suggesting activity of pomalidomide in the setting of EMD and the increased tissue distribution with the oral proteasome inhibitor ixazomib, we designed this trial to examine if the all oral combination of ixazomib, pomalidomide and dexamethasone can be effective in the setting of EMD. Patients and Methods: Patients with previously treated multiple myeloma, with adequate hematologic and organ function were enrolled if there was evidence, at study entry, of EMD defined as one or more plasmacytomas, outside the bone marrow that were non-contiguous with a bone lesion and had a single diameter of ≥2 cm OR as plasma cell leukemia, with circulating plasma cells &gt; 5% of peripheral blood leukocytes or at least 0.5 X 109/L or 200 cells/150000 events by flowcytometry. Patients were treated on 28-day cycles, with ixazomib 4 mg on days 1, 8, and 15 along with pomalidomide 4 mg PO daily on days 1-21 and dexamethasone 40 milligrams weekly until disease progression or unacceptable toxicity. The goals of the study were to determine confirmed response rate (≥ PR), toxicities of this combination, differential response rates and progression-free survival (PFS). Confirmed response rate, differential response rates and PFS were estimated using Duffy and Santner approach, exact binomial distributions and Kaplan Meier curves, respectively. The study was designed to accrue 30 patients. Results: This study was designed to enroll up to 30 patients but was closed after enrolling 17 patients due to slow accrual. The baseline characteristics are as indicated in Table 1. Eleven patients were enrolled with an extramedullary plasmacytoma while the remaining six patients had plasma cell leukemia. Median number of lines of prior therapy was 3 (range: 1, 7). Overall, 10 (58.8%) patients had progressive disease and 11 (64.7%) patients have died, median (range) follow-up for the live patients is 22.2 (2.1, 37.9) months. Patients were treated for a median of 2 (range 1-34) cycles. A grade 3+ AE, at least possibly attributed, was seen in 53%. Grade 3+, at least possibly related, hematologic toxicity was noted in 41%, with 29% experiencing grade 3+ neutropenia. Notable grade 3+ non-hematologic toxicities (regardless of attribution), with &gt;10% incidence rate were anemia, hypoxia, infections and lung infection. The confirmed response rate in evaluable patients was 35% (1 CRs and 5 PRs), with a 90% CI of 6% - 37%. While 33% (4/12; 95% CI: 1-8%) of patients reported a biochemical response, 40% (2/5; 95% CI: 0-4%) of patients reported an extramedullary response. The median PFS was 4.5 (95% CI: 2-11.8) months. Conclusions: The combination of ixazomib, pomalidomide and dexamethasone resulted in disease response in a third of this group of high-risk patients with EMD; however, the responses were not very durable, with a median PFS of only 4.5 months. The trial highlights the feasibility of doing clinical trials specifically targeted towards this high-risk patient population. Future trials should explore combinations of novel agents, including monoclonal antibodies through multicenter collaborative efforts. Disclosures Kansagra: Alnylam Pharmaceuticals, Bristol Myers Squibb /Celgene, GlaxoSmithKline, Janssen, Pharmacyclics, Takeda Pharmaceuticals, Pfizer, Karyopharm Therpeutics: Other: Advisory Board. Witzig:Spectrum: Consultancy; Immune Design: Research Funding; Karyopharm Therapeutics: Research Funding; Acerta: Research Funding; Incyte: Consultancy; AbbVie: Consultancy; MorphSys: Consultancy; Celgene: Consultancy, Research Funding. Kumar:Oncopeptides: Consultancy, Other: Independent Review Committee; IRC member; Genecentrix: Consultancy; Carsgen: Other, Research Funding; Cellectar: Other; Celgene/BMS: Other: Research funding for clinical trials to the institution, Consulting/Advisory Board participation with no personal payments; Dr. Reddy's Laboratories: Honoraria; AbbVie: Other: Research funding for clinical trials to the institution, Consulting/Advisory Board participation with no personal payments; Takeda: 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; 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; Kite Pharma: Consultancy, Research Funding; Novartis: Research Funding; Adaptive Biotechnologies: Consultancy; Genentech/Roche: Other: Research funding for clinical trials to the institution, Consulting/Advisory Board participation with no personal payments; BMS: Consultancy, Research Funding; Karyopharm: Consultancy; MedImmune: Research Funding; Sanofi: Research Funding; Tenebio: Other, 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.