Abstract: Background: For multiple myeloma (MM) patients, depth of response after induction therapy and after autologous hematopoietic stem cell transplantation (AHCT) has been shown to be important for progression free (PFS) and overall survival (OS) in some studies. Furthermore, the impact of minimal residual disease (MRD) on outcomes and treatment decisions has been widely discussed. We aimed to evaluate outcomes by depth of response after induction and AHCT. Methods: MM patients who received their first AHCT within 1 year of starting induction were identified from the institutional registry. MRD was assessed by non-10 color flow cytometry. Response was defined by the International Myeloma Working Group criteria. Summary statistics were used to describe the population. Kaplan-Meier methodology estimated PFS and OS by response status pre-AHCT and at post-AHCT restaging. Results: Between 2012 - 2014, 182 MM patients met our inclusion criteria, with 83% alive at last follow-up. The median age at AHCT was 60 years (range 29-76) with 57% male. By the International Staging System (ISS), 50% were stage I, 26% stage II, and 24% stage III. High risk cytogenetics were detected in 24%. Isotype was IgG in 55%, IgA 21%, Kappa Free Light Chain (KFLC) 11%, and lambda FLC (LFCL) 9%. First induction therapy included bortezomib in 90% and lenalidomide in 79%. Median time to AHCT was 5.5 months (range 2.8-11.7). The median follow-up from AHCT was 3.7 years (range 0.22 - 4.6 years), with 84% of patients receiving lenalidomide maintenance, and 9% receiving an additional autologous or allogenic transplant at relapse. Response prior to the initial AHCT was a complete remission (CR) in 13.7% (MRD negative 6.6%, positive 4.4%, unknown 2.7%), very good partial remission (VGPR) 38%, partial remission (PR) 40%, stable disease (SD) 5%, and progressive disease (PD) 4%. At post-AHCT restaging, responses had improved to 42% CR (MRD negative 23%, positive 6%, unknown 13%), 35% VGPR, 19% PR, 2% SD, and 3% PD. Median PFS from AHCT for the entire cohort was 3.2 years (95% CI 2.4 - 4 years) with 1-year and 3-year PFS 85% and 52%, respectively. Median OS was not reached (NR) (95% CI 4.4 years - NR) with 1-year and 3-year OS 97% and 88%, respectively (Figure 1). PFS from AHCT was significantly longer in patients with an MRD negative CR prior to AHCT with median PFS not reached (95% CI 1.7 - NR) compared to MRD positive/unknown CR, VGPR, and ≤ PR [3.64 years (95% CI 1.09-3.64), 3.46 years (95% CI 2.4 - NR), and 2.44 years (1.68-3.56 years), respectively, p=0.048] (Figure 2A). From post-AHCT restaging, PFS was also significantly longer in patients with an MRD negative CR prior to AHCT with median PFS not reached compared to MRD positive/unknown CR, VGPR, and ≤ PR [3.49 years (95% CI 0.86-3.49), 3.56 years (95% CI 2.5 - NR), and 2.4 years (1.6-3.33 years), respectively, p=0.026] (Figure 2B). However, there was no difference in PFS based on the post-AHCT restaging with median PFS in MRD negative CR, MRD positive/unknown CR, VGPR, and ≤ PR of 3.49 years (95% CI 2-NR), not reached (95% CI 1.4-NR), 2.96 years (95% CI 1.7-NR), and 2.86 years (95% CI 1.7 - NR) (p=0.78, Figure 2C), respectively. OS from AHCT was not significantly different by pre-AHCT response, and the median was not reached in any group (p=0.33, Figure 3A). Finally, the median OS from post-AHCT restaging by pre-AHCT response or by post-AHCT response was also not reached in any group (p=0.32 and 0.31, respectively; Figure 3B & C). Conclusion: For MM patients, AHCT deepened responses and increased the CR rate. We were unable to show a significant difference in outcomes at post AHCT restaging, which may be due to the effect of maintenance therapy, the small numbers of MRD negative patients, or the sensitivity of the MRD assay available during this time period, though potentially show that MRD positive patients do as well as MRD negative patients after AHCT. We plan to add additional patients treated in the more recent years who were assessed by more sensitive methods. Disclosures Shah: Janssen: Research Funding; Amgen: Research Funding. Korde:Amgen: Research Funding. Lesokhin:Janssen: Research Funding; Genentech: Research Funding; Takeda: Consultancy, Honoraria; Serametrix, inc.: Patents & Royalties: Royalties; Bristol-Myers Squibb: Consultancy, Honoraria, Research Funding; Squibb: Consultancy, Honoraria. Mailankody:Janssen: Research Funding; Physician Education Resource: Honoraria; Takeda: Research Funding; Juno: Research Funding. Smith:Celgene: Consultancy, Patents & Royalties: CAR T cell therapies for MM, Research Funding. Landgren:Takeda: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Pfizer: Consultancy; Merck: Membership on an entity's Board of Directors or advisory committees; Karyopharm: Consultancy; Janssen: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Amgen: Consultancy, Research Funding; Celgene: Consultancy, Research Funding.

Abstract: Background: Monoclonal immunoglobulin deposition disease (MIDD) is a rare complication of plasma cell dyscrasias in which deposition of immunoglobulin light and/or heavy chains results in organ dysfunction, most commonly affecting the kidneys. MIDD can present with new onset hypertension, hematuria, renal insufficiency and proteinuria. The rarity of MIDD contributes to the uncertainty regarding optimal therapy (typically targeting the clonal plasma cells), and the relationship between hematologic response and renal outcome. We report here the experience at Memorial Sloan Kettering Cancer Center and New York Presbyterian Hospital/Weill Cornell Medical Center. Methods: An electronic query of pathology records was performed to identify patients with a biopsy-proven diagnosis of MIDD. Patients were eligible for inclusion in this analysis if they had received treatment and had been subsequently followed at either institution. A retrospective review of clinical records extracted patients' baseline characteristics and treatment history. Hematologic responses were assessed according to International Myeloma Working Group uniform response criteria (Kumar, S. et al 2016 Lancet Oncol 17(8): e328-346) and renal organ responses were evaluated based on changes in serum creatinine (SCr), and proteinuria, a modification of criteria previously reported (Kourelis, T. V., et al 2016, Am J Hematol 91(11): 1123-1128.; Nasr, S.H. et al. 2009, J Am Soc Nephrol 20(9): 2055-2064. The primary objective was to determine the rate of hematologic response after initial therapy. Secondary objectives included: (i) Estimation of renal response rate; (ii) Identification of risk factors associated with renal response using the Wilcoxon Rank Sum and Fisher's Exact Tests. Results: Among 54 patients identified who were diagnosed and started treatment between 1/1999 and 1/2016, 29 met criteria for inclusion. Baseline characteristics at diagnosis included: Median age of 50 (range, 32-79); 17 (59%) were male; 22 (75%) had hypertension. Renal parameters at diagnosis: median SCr of 2.4 mg/dl (range, 0.4-19), median CrCl 23 ml/min (range, 4-131), median proteinuria 2383.7mg/24h (range 4.7-13,000), nephrotic-range proteinuria syndrome in 13 (45%), hematuria in 4/25 pts (16%; 4 unknown), 7 were on hemodialysis (HD) prior to initiation of therapy, and 26 (90%) patients had monoclonal kappa light chain deposits. Hematologic parameters included median free light chain ratio of 67.9 (2.8-1179.0), detectable M-spike in 11 pts with a mean level of 0.6 g/dL and median bone marrow plasmacytosis of 20% (range, 0-90%). Induction treatment regimens included bortezomib in 18 (62%), lenalidomide in 6 (21%), cyclophosphamide in 8 (28%), and 21 (73%) underwent autologous stem cell transplant (ASCT) during the course of their treatment. Outcomes are shown in Table 1. Hematologic response among the 29 pts at completion of first line therapy included an overall response rate (ORR) of 93% with sCR (N=14, 48%); CR (N=5, 17%), VGPR (N=6, 20%), PR (N=2, 6.9%), Not available (N=2, 7%). Renal response (Table 1) among 29 patients included CR (N=9, 31%), PR (N=14, 48%) and End Stage Renal Disease (ESRD) (N=6, 21%). Among 7 patients on HD at baseline, 3 remained on HD despite treatment, while 4 stopped HD after treatment, 2 as a result of the treatment and 2 after renal transplant. 3 patients progressed to ESRD and required HD during treatment. Baseline beta-2 microglobulin (B2M), SCr, and eGFR at diagnosis were factors associated with renal response (p 〈 0.05). Hematologic response (CR vs. non-CR) was not associated with renal response (p=0.68) in this cohort. Conclusions: In this cohort, we observed a high rate of hematologic response (65.5% reaching CR) to upfront treatment regimens. A majority of patients received bortezomib-based regimens and ASCT. We observed a large proportion of patients whose renal impairment from MIDD improved significantly after receiving therapy directed at the underlying clonal neoplasm, with 75.8% reaching PR or better, nearly a third of patients achieving a renal CR, and 2/7 patients on HD at diagnosis discontinuing HD after treatment. Our experience presented here serves to inform the treatment approach of patients with MIDD. Given the scarcity of outcome data in MIDD, especially in the era of novel anti-myeloma therapy, prospective studies to optimize the management of these patients are needed. Disclosures Rossi: Celgene: Consultancy. Smith:Celgene: Consultancy, Patents & Royalties: CAR T cell therapies for MM, Research Funding. Korde:Amgen: Research Funding. Mailankody:Janssen: Research Funding; Juno: Research Funding; Physician Education Resource: Honoraria; Takeda: Research Funding. Lesokhin:Squibb: Consultancy, Honoraria; Bristol-Myers Squibb: Consultancy, Honoraria, Research Funding; Takeda: Consultancy, Honoraria; Genentech: Research Funding; Janssen: Research Funding; Serametrix, inc.: Patents & Royalties: Royalties. Landgren:Janssen: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Karyopharm: Consultancy; Merck: Membership on an entity's Board of Directors or advisory committees; Pfizer: Consultancy; Celgene: Consultancy, Research Funding; Amgen: Consultancy, Research Funding; Takeda: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding. Hassoun:Oncopeptides AB: Research Funding.

Abstract: Introduction Newly diagnosed multiple myeloma (NDMM) patients who achieve and maintain minimal residual disease (MRD) negativity demonstrate clinical benefit with prolonged progression-free survival and overall survival. Based on available data showing MRD negativity with standard dose KRD (36 mg/m2) approximating 40% (Korde JamaOnc 2015), we designed a MRD response-adapted treatment study for NDMM, where the number of treatment cycles is determined based on MRD status, instead of the traditional paradigm of fixed number of cycles followed by autologous hematopoietic cell transplantation (AHCT). We integrated a flow-based MRD driven platform in this phase I/II study evaluating higher doses of twice-weekly carfilzomib (Car) (45 and 56 mg/m2) in combination with lenalidomide (Len) and dexamethasone (Dex). Methods Eligible NDMM patients were given escalating doses of Car (45 and 56 mg/m2), Len, and Dex in a single arm, phase I standard 3+3 schema design, based on dose-limiting toxicities (DLTs) occurring in cycle 1. Treatment consisted of 28-day cycles with Car 20/45 mg/m2 or 20/56 mg/m2 - days 1, 2, 8, 9 15 and 16; Len 25 mg - days 1-21; and Dex 40 mg weekly cycles 1-4, 20 mg after cycle 4. AHCT eligible patients underwent stem cell collection after 6 cycles, and then continue with protocol therapy. Patients achieving MRD negative status (serum, urine, and bone marrow with 10-color flow) received 2 additional cycles from the time of conversion and then stop therapy. Patients with less than an MRD negative response after any cycle continued therapy until treatment completion (max 12 cycles), disease progression, or unacceptable toxicity. The primary endpoint of the phase II study was to determine the MRD negative rate at the MTD dose, using a Simon's optimal two-stage design. Herein, we have updated results on phase I and phase II portions of the study with a median follow-up of 20.7 months (1.4-31.1). For available data, we present MFC and NGS MRD platforms. Results Twenty-nine patients have enrolled onto study between October 2016 - June 2018, with 18 in phase 1 and stage I of phase II and 11 in stage II of phase II, thus completing target accrual. There were 16 males, 13 females, median age 61 (43-75) years. Baseline characteristics included 18(62%) ISS-I, 9(31%) ISS-II, and 2(7%) ISS-III, and 7(24%) patients high risk FISH (t(4,14), t(14,16), p53 deletion). There were no DLTs within the first cycle that met protocol criteria (0/3 patients in 20/45 mg/m2 cohort and 0/6 patients in 20/56 mg/m2). The MTD chosen was 20/56 mg/m2, and an additional 20 patients were enrolled. Three patients came off study (56 mg/m2 cohort): one due to MI (during C2); one due to intolerable rash (during C2); and one due to personal preference (during C2). Among all 29 patients, grade 3/4 non-hematologic toxicities included 6(21%) rash, 5(17%) electrolyte disturbances, 4(14%) infections, 3(10%) GI, 2(7%) cardiopulmonary, 2(7%) VTE, 2(7%) mood, 2(7%) cataract, and 1(3%) hyperglycemia, and grade 3/4 hematologic toxicities included 12(41%) lymphopenia, 2(7%) leukopenia, 1(3%) neutropenia, and 1(3%) thrombocytopenia. Ten patients had 13 SAEs. For the 15 patients completing protocol therapy, a median number of 11 (7-12) cycles were delivered, and best responses include 9(60%) sCR/CR MRD neg and 6(40%) obtaining VGPR. Among patients reaching sCR/CR MRD neg status, the median time to reach was 8 (5-9) cycles. Among the eleven patients currently remaining on study, 7 have received at least 1 cycle of therapy (response eligible) and best responses thus far, included 1(14%) sCR/CR MRD pending, 4(57%) VGPR, and 2(29%) PR with a median number of 4 (1-8) cycles delivered. Table comparison of MRD platforms shown in sCR/CR patients. Among patients that remain on study, median 20.7 months, no patients have progressed and all remain alive. One patient that came off study due to personal preference during cycle 2 achieved a PR, and has progressed since. Conclusion In this phase I/II clinical trial assessing higher doses of twice-weekly Car dosing in combination with Len and Dex, we established MTD 56 mg/m2 and demonstrated a MRD platform using multi-parametric flow cytometry can be successfully used to tailor individualized treatment plans. Higher doses of twice weekly Car (45 and 56 mg/m2) in combination with Len and Dex, resulted in rapid and deep responses with approximately 60% MRD negative rate, and a safety profile similar to KRD standard dose (Car 36 mg/m2). Table. Table. Disclosures Korde: Amgen: Research Funding. Mailankody:Janssen: Research Funding; Physician Education Resource: Honoraria; Takeda: Research Funding; Juno: Research Funding. Hassoun:Oncopeptides AB: Research Funding. Lesokhin:Janssen: Research Funding; Squibb: Consultancy, Honoraria; Genentech: Research Funding; Bristol-Myers Squibb: Consultancy, Honoraria, Research Funding; Serametrix, inc.: Patents & Royalties: Royalties; Takeda: Consultancy, Honoraria. Smith:Celgene: Consultancy, Patents & Royalties: CAR T cell therapies for MM, Research Funding. Arcila:Invivoscribe, Inc.: Consultancy, Honoraria. Ho:Invivoscribe, Inc.: Honoraria. Landgren:Janssen: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Celgene: Consultancy, Research Funding; Merck: Membership on an entity's Board of Directors or advisory committees; Takeda: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Amgen: Consultancy, Research Funding; Karyopharm: Consultancy; Pfizer: Consultancy.

Abstract: 8051 Background: Patients with high risk smoldering multiple myeloma (HR-SMM) have an increased risk of progression to multiple myeloma (MM)- median time 〈 2 years. The standard management of these patients currently is close clinical monitoring; however, randomized trials show longer progression-free and overall survival in in HR-SMM patients treated with the oral immunomodulatory drug lenalidomide. We report the use ixazomib, the first oral proteasome inhibitor, in combination with dexamethasone in the setting of HR-SMM. Because proteasome inhibitors can provide deep clinical responses in patients with MM, we set the pre-specified threshold for efficacy high (overall response rate of ≥75%). Methods: In this single arm pilot trial of ixazomib/dexamethasone, patients received 12 4-week cycles of ixazomib/dexamethasone followed by ixazomib maintenance for 24 cycles. The primary endpoint is best overall response after 12 cycles and second objectives include duration of response, safety, and progression free survival. Results: 14 patients with HR-SMM were enrolled between 06/2016 and 03/2018. The median age is 65 years and 10 (71%) of patients were male. 11 (79%) patients were high-risk by the PETHEMA criteria, 2 (14%) by the Mayo Clinic criteria and 1 (7%) by both. At data cut-off (02/07/2019), patients completed a median of 17 cycles and 10 (71%) are continuing treatment. 4 patients have stopped treatment (2 patients for raise in serum markers without progression to MM, and 1 each for toxicities, and co-morbidities unrelated to treatment). 9 (64%) achieved an objective response (8 PR, and 1 VGPR) and no patient has progressed to MM. Non-heme adverse events included 3 grade 1 GI events, 2 grade 3 lung infection, 1 grade 2 acute kidney injury, and 1 had grade 1 fatigue that was possibly related to treatment. Conclusions: Ixazomib/dexamethasone appears well tolerated with high overall response (9/14; 64%) in patients with HR-SMM. Although the trial does not meet our pre-specified threshold for efficacy (i.e. best overall response rate of 75%), with a median follow-up of 17 months, no patient progressed to MM and only 2 patients had serologic progression. These results support further evaluation of ixazomib/dexamethasone alone and in combination with other agents as treatment for patients with HR-SMM. Clinical trial information: NCT02697383.