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Orlowski, Robert Z.

0000-0002-5723-4129

A5038235561 | I1343551460

Mayo Clinic

The University of Texas MD Anderson Cancer Center

Citations 107

Low-dose versus High-dose Carfilzomib with Dexamethasone (S1304) in Patients with Relapsed-Refractory Multiple Myeloma

Clinical Cancer Research | April 16, 2020 | Volume: 26 | Issue: 15 | Pages: 3969-3978

10.1158/1078-0432.ccr-19-1997 | PMID 32299820

Abstract Purpose: Treatment of multiple myeloma has evolved tremendously and optimal utilization of available therapies will ensure maximal patient benefits. Patients and Methods: We report the Southwest Oncology Group randomized phase II trial (S1304) comparing twice weekly low-dose (27 mg/m2; arm 1) to high-dose carfilzomib (56 mg/m2; arm 2), both with dexamethasone, administered for 12 cycles (11 months) for relapsed and/or refractory multiple myeloma with up to six prior lines of therapy (NCT01903811). The primary endpoint was progression-free survival (PFS), and patients on arm 1 could cross-over to arm 2 after progression on treatment. Results: Among 143 enrolled patients, of whom 121 were eligible and analyzable, the overall response rate was 42.8%, with no significant difference between the arms (P = 0.113). Also, neither the median PFS [5 months and 8 months, respectively; HR, 1.061; 80% Wald confidence interval (CI), 0.821–1.370; P = 0.384] nor the median overall survival were significantly different (26 and 22 months, respectively; HR, 1.149, 80% Wald CI, 0.841–.571; P = 0.284). Sixteen patients crossed over to arm 2 with a median PFS benefit of 3 months. Certain adverse events (AE) were more frequent in arm 2, including fatigue, thrombocytopenia, and peripheral neuropathy, but there was no significant difference in cardiopulmonary AEs. Conclusions: This randomized trial did not support a benefit of fixed duration, twice weekly 56 mg/m2 dosing of carfilzomib over the 27 mg/m2 dose for the treatment of relapsed and/or refractory multiple myeloma. However, treatment to progression in earlier patient populations with high-dose carfilzomib using different schedules should still be considered as part of the standard of care.
Once-weekly (70 mg/m2) versus twice-weekly (56 mg/m2) dosing of carfilzomib (CFZ) for patients (pts) with relapsed and/or refractory multiple myeloma (RRMM).

Journal of Clinical Oncology | March 12, 2020 | Volume: 37 | Issue: 15_suppl | Pages: e19505-e19505

10.1200/jco.2019.37.15_suppl.e19505

e19505 Background: CFZ combined with dexamethasone is approved to treat pts with RRMM, with CFZ given once-weekly at 70 mg/m2 (Kd70 QW) or twice-weekly at 56 mg/m2 (Kd56 BIW). No randomized trials have directly compared Kd70 QW with Kd56 BIW. We performed a post hoc comparison between pts who received Kd56 BIW in the ENDEAVOR trial and pts who received Kd70 QW in the A.R.R.O.W. or CHAMPION-1 trials. Methods: Data were analyzed from 3 trials of CFZ in RRMM: A.R.R.O.W. (240 pts in Kd70 QW arm; 2–3 prior therapies and refractory to most recent therapy), CHAMPION-1 (104 pts received Kd70 QW; 1–3 prior therapies), and ENDEAVOR (464 pts in Kd56 BIW arm; 1–3 prior therapies). Pts who received Kd70 QW in A.R.R.O.W. and CHAMPION-1 were pooled and compared with pts who received Kd56 BIW in ENDEAVOR. As study populations slightly varied among the 3 trials, an analysis of safety and efficacy was performed in a subgroup of pts who received 2–3 prior therapy lines and were not refractory to bortezomib (BTZ). Also, we performed regression analyses (controlling for age, ISS stage, BTZ and lenalidomide refractory status, and number of prior regimens) among all pts in the trials who received Kd70 QW or Kd56 BIW. Results: Among BTZ non-refractory pts with 2–3 lines of prior therapy, median progression-free survival (PFS) was 12.1 months (95% CI 8.4–14.3) for Kd70 QW (n = 146) and 14.5 months (95% CI 10.2–NE) for Kd56 BIW (n = 217), and the overall response rate (ORR) was 69.9% (95% CI 61.7–77.2) for Kd70 QW and 72.4% (95% CI 65.9–78.2) for Kd56 BIW. The rate of grade ≥3 adverse events (Kd70 QW vs Kd56 BIW) was 67.6% and 85.3%; among adverse events of interest, the grade ≥3 rate was 1.4% and 5.1% for cardiac failure, 3.4% and 6.0% for renal failure, and 5.5% and 15.7% for hypertension. Kd70 QW represents a convenient and well-tolerated treatment modality for pts with RRMM. In a Cox proportional hazards model, the hazard ratio for PFS (Kd70 QW vs Kd56 BIW) was 0.91 (95% CI 0.69–1.19), and in a logistic regression model the odds ratio for ORR (Kd70 QW vs Kd56 BIW) was 1.12 (95% CI 0.74–1.69). Conclusions: This post hoc analysis suggests that once-weekly Kd70 has a comparable benefit-risk profile to twice-weekly Kd56. Clinical trial information: NCT02412878, NCT01677858, NCT01568866.
E3A06: Randomized phase III trial of lenalidomide versus observation alone in patients with asymptomatic high-risk smoldering multiple myeloma.

Journal of Clinical Oncology | March 12, 2020 | Volume: 37 | Issue: 15_suppl | Pages: 8001-8001

10.1200/jco.2019.37.15_suppl.8001

8001 Background: Smoldering multiple myeloma (SMM) is a precursor to myeloma, wherein current standard of care is observation (obs). Data from a randomized Spanish trial (Mateos et al, NEJM 2015) suggest that lenalidomide(len)/dexamethasone improves time to developing myeloma (TTP) and overall survival (OS) for patients (pts) with high risk (HR) SMM over obs. However, pts were not screened with advanced imaging techniques, used a HR definition that is not routinely available, and combination therapy limited the ability to isolate the effect of len, and thus has not become standard of care. Methods: E3A06 is a randomized phase III intergroup trial, testing the effect of single agent len compared with obs for pts with intermediate or high risk SMM. In an initial phase II run in all pts received len to demonstrate safety. Eligibility required ≥10% PCs and abnormal serum FLC ratio (<0.26 or >1.65). The primary endpoint was progression PFS was estimated by the Kaplan-Meier method and compared using the one-sided stratified log-rank test. Results: PII enrolled 44 pts and PIII randomized 182 pts to either len (n=90) or obs (n=92) [stratified on time since SMM diagnosis ≤1y vs >1y]. Baseline characteristics were similar between the arms. 80% (PII) and 51% (PIII) are off len, primarily due to adverse events (AE) or pt withdrawal. Among the len treated pts, G3/4 non-hematologic AE occurred in 28% of PIII pts with fatigue being most common (n=5). G4 hematologic AE rate was 5.7%, primarily neutropenia (n=4). 3-year cumulative incidence of invasive SPMs was 5.2% (len) and 3.5% (obs). Overall response rate was 47.7% for the phase II study, and in phase III, 48.9% for the len arm, and 0% for the obs arm. Median follow up was 71 months (PII), and 28 months (PIII). 3-year PFS was 87% for the PII cohort. One, 2 and 3-year PFS was 98%, 93%, and 91% for len, and 89%, 76%, and 66% for the obs arm (HR 0.28, p=0.0005) favoring the len arm. No difference in QOL score was noted between arms. Conclusions: Overall, this trial represents the largest randomized trial in SMM to date. In conjunction with the Spanish data, this trial may support a change in clinical practice. Clinical trial information: NCT01169337. [Table: see text]
Strategies to overcome barriers to accrual (BtA) to NCI-sponsored clinical trials: A project of the NCI-Myeloma Steering Committee Accrual Working Group (NCI-MYSC AWG).

Journal of Clinical Oncology | March 12, 2020 | Volume: 31 | Issue: 15_suppl | Pages: 8592-8592

10.1200/jco.2013.31.15_suppl.8592

8592 Background: Accrual to NCI clinical trials(CT)is often slower than planned at times mandating premature closure resulting in loss of valuable resources and delay of scientific progress. Methods: The NCI-MYSC AWG identified 10 potential BtA. SWOG, ECOG and Alliance investigators were queried and agreed that these barriers impede accrual (results stratified for academic and community sites). The MYSC AWG developed in collaboration with NCI and FDA strategies to overcome these barriers. Results: Strategies listed for the 3 most often cited BtA: 1. Reimbursement for CT related expenses:increase awareness of improved reimbursement for phase II CT; tailor reimbursement according to CT complexity; request funds from industry and other sources ( http://biqsfp.cancer.gov ) for qualifying ancillary CT components. 2. Spectrum of available treatment options influences CT participation: educate patients and providers about the significance of a new CT using social media, presentations at national meetings and by adding educational material to CT protocol; encourage opinion leaders and advocacy groups not to promote a new therapy as “standard” in the absence of phase III data. 3. Requirement of CT specific therapy at NCI designated sites only: “MYSC AWG Drug Administration Table” describes NCI/FDA approved rules for CT specific drug administration; CT protocol will outline which standard treatment components of a CT can be administered at any site as long as protocol specific guidelines are followed and conduct is supervised by enrolling investigator. Examples of additional strategies to overcome identified BtA: determine feasibility, indication and insurance coverage of CT specific tests during protocol development; discourage narrow eligibility criteria; avoid competing CT; allow up to 1 cycle of commercially available therapy prior to enrollment; CIRB support for phase II CT. Conclusions: The MYSC Accrual Working Group developed in collaboration with NCI and FDA strategies to overcome barriers to myeloma clinical trial accrual. These strategies may be applicable to NCI-sponsored clinical trials evaluating interventions in other diseases.
Response rates to single-agent carfilzomib in patients refractory or intolerant to both bortezomib and immunomodulators in trial PX-171-003-A1.

Journal of Clinical Oncology | March 11, 2020 | Volume: 30 | Issue: 15_suppl | Pages: 8035-8035

10.1200/jco.2012.30.15_suppl.8035

8035 Background: Patients (pts) with relapsed and refractory multiple myeloma (RR MM) who are refractory or intolerant to both bortezomib (BTZ) and immunomodulators (IMiDs; thalidomide [Thal] or lenalidomide [Len]) (ie, “double-refractory/intolerant”), have few therapeutic options and a poor prognosis. Carfilzomib (CFZ), a next generation proteasome inhibitor (PI), has shown durable single-agent activity in clinical studies including 003-A1, an open-label, single-arm phase 2b trial in RR MM. The present analysis describes clinical activity in pts from 003-A1 with double-refractory/intolerant disease and in other groups of clinical interest including pts with disease refractory to all 5 approved classes of anti-MM tx (alkylators, anthracyclines, corticosteroids, IMiDs, and PIs) in clinical use (“refractory to all approved tx”). Methods: Pts from 003-A1 with double-refractory/intolerant disease were analyzed, as were pts with disease refractory to all approved tx. CFZ was given on days 1, 2, 8, 9, 15, 16 of 28-day cycles (C), (20 mg/m2 in C1; 27 mg/m2 in C2–12). Primary endpoint was overall response rate (ORR). Secondary endpoints included duration of response (DOR), overall survival, and safety. Results: The study ORR was 22.9% with median DOR of 7.8 mo (N=266). 228 pts (86%) with double-refractory/intolerant disease had ORRs of 20.6% and a median DOR of 7.4 mo. Conclusions: Single-agent CFZ demonstrated clinically meaningful, durable responses in pts with double-refractory/intolerant MM or disease refractory to all 5 approved classes of tx. The ORRs across groups of clinical interest were generally consistent with results for the entire study population. These results are notable for a next-generation PI and demonstrate the activity of single-agent CFZ in pts with advanced stage MM. [Table: see text]
Phase I evaluation of carfilzomib (PR-171) in hematological malignancies: Responses in multiple myeloma and Waldenstrom’s macroglobulinemia at well-tolerated doses

Journal of Clinical Oncology | March 6, 2020 | Volume: 25 | Issue: 18_suppl | Pages: 8003-8003

10.1200/jco.2007.25.18_suppl.8003

8003 Background: Carfilzomib is a novel, irreversible tetrapeptide proteasome inhibitor derived from the natural product epoxomicin. Carfilzomib was well tolerated in preclinical animal studies when administered on a two-week cycle, QDx5; proteasome inhibition one hour after dosing at the MTD was >80%. Two Phase I dose-escalation studies are ongoing, aimed at determining the safety, tolerability, and biological response to carfilzomib. Methods: Carfilzomib was administered according to two different dose-intensive schedules. In PX-171–001, carfilzomib was administered on a two week cycle, QDx5 with nine days rest; in PX-171–002, carfilzomib was administered on a four week cycle, QDx2 weekly for three weeks with 12 days rest. Eligible patients have multiple myeloma (MM), Non-Hodgkin's Lymphoma (NHL), Hodgkin's Disease (HD), or Waldenström's Macroglobulinemia (WM). Results: Thus far, a total of 54 subjects have been enrolled. Although the maximum tolerated dose (MTD) has not yet been identified on either study, responses seen on both protocols have established 11 and 15 mg/m2 as the minimal effective doses (MEDs) on PX-171–001 and 002, respectively. Of 3 patients with MM or WM treated on the 001 protocol, one MM patient has had a Partial Response (PR) and one WM patient had a Minimal Response (MR). Of 8 patients with MM treated on the 002 protocol, 3 patients have had PRs. 6 additional patients have had Stable Disease lasting longer than 6 months and symptomatic improvement has been seen in patients on both protocols. 11 subjects remain on study with stable disease or better. Proteasome inhibition in whole blood at the highest dose levels exceeded 80% one hour after the first dose. Carfilzomib has been well tolerated at doses at and above the MED thus far. There has been no incidence of painful peripheral neuropathy on either study. No dose-limiting toxicities (DLTs) have occurred on PX-171–001; one DLT (Gr 4 anemia and thrombocytopenia) was observed at 27 mg/m2 on PX-171–002. Conclusions: Thus far, intensive dosing with carfilzomib is well-tolerated at proteasome inhibition levels of more than 80%. Five responses have been observed, and several subjects have achieved long lasting SD and/or symptomatic improvement. No significant financial relationships to disclose.
Once‐weekly (70 mg/m 2 ) vs twice‐weekly (56 mg/m 2 ) dosing of carfilzomib in patients with relapsed or refractory multiple myeloma: A post hoc analysis

Cancer Medicine | February 28, 2020 | Volume: 9 | Issue: 9 | Pages: 2989-2996

10.1002/cam4.2945 | PMID 32108443

Abstract Combination of carfilzomib with dexamethasone (Kd) is approved for use in relapsed and/or refractory multiple myeloma (RRMM), with carfilzomib administered twice weekly at 56 mg/m 2 (Kd56 BIW) or once weekly at 70 mg/m 2 (Kd70 QW). Post hoc cross‐trial comparisons were performed to compare efficacy and safety profiles of Kd70 QW vs Kd56 BIW dosing schedules using data from three trials of patients with RRMM: A.R.R.O.W., CHAMPION‐1, and ENDEAVOR. To select for comparable patient populations, side‐by‐side efficacy and safety comparisons were performed in subgroups of patients with 2‐3 prior lines of therapy who were not refractory to bortezomib. The overall response rate (ORR) was 69.9% (95% confidence interval [CI], 61.7‐77.2) for Kd70 QW and 72.4% (95% CI, 65.9‐78.2) for Kd56 BIW. Median progression‐free survival (PFS) was 12.1 months (95% CI, 8.4‐14.3) for Kd70 QW and 14.5 months (95% CI, 10.2—not evaluable) for Kd56 BIW. Frequency of grade ≥ 3 adverse events (AEs) was 67.6% for Kd70 QW and 85.3% for Kd56 BIW. Regression analyses (adjusting for prognostic factors) of all patients in the trials who received Kd70 QW vs Kd56 BIW estimated a PFS hazard ratio of 0.91 (95% CI, 0.69‐1.19; P = .47) and an ORR odds ratio of 1.12 (95% CI, 0.74‐1.69; P = .61). These results suggest that Kd70 QW has a comparable efficacy profile compared with Kd56 BIW and represents a convenient and well‐tolerated treatment for patients with RRMM.
A meta-analysis of genome-wide association studies of multiple myeloma among men and women of African ancestry

Blood Advances | January 14, 2020 | Volume: 4 | Issue: 1 | Pages: 181-190

10.1182/bloodadvances.2019000491 | PMID 31935283

Abstract Persons of African ancestry (AA) have a twofold higher risk for multiple myeloma (MM) compared with persons of European ancestry (EA). Genome-wide association studies (GWASs) support a genetic contribution to MM etiology in individuals of EA. Little is known about genetic risk factors for MM in individuals of AA. We performed a meta-analysis of 2 GWASs of MM in 1813 cases and 8871 controls and conducted an admixture mapping scan to identify risk alleles. We fine-mapped the 23 known susceptibility loci to find markers that could better capture MM risk in individuals of AA and constructed a polygenic risk score (PRS) to assess the aggregated effect of known MM risk alleles. In GWAS meta-analysis, we identified 2 suggestive novel loci located at 9p24.3 and 9p13.1 at P &lt; 1 × 10−6; however, no genome-wide significant association was noted. In admixture mapping, we observed a genome-wide significant inverse association between local AA at 2p24.1-23.1 and MM risk in AA individuals. Of the 23 known EA risk variants, 20 showed directional consistency, and 9 replicated at P &lt; .05 in AA individuals. In 8 regions, we identified markers that better capture MM risk in persons with AA. AA individuals with a PRS in the top 10% had a 1.82-fold (95% confidence interval, 1.56-2.11) increased MM risk compared with those with average risk (25%-75%). The strongest functional association was between the risk allele for variant rs56219066 at 5q15 and lower ELL2 expression (P = 5.1 × 10−12). Our study shows that common genetic variation contributes to MM risk in individuals with AA.
Disease and Outcome Disparities in Multiple Myeloma (MM): Exploring the Role of Race/Ethnicity and Obesity in Cooperative Group Clinical Trials

Blood | November 17, 2019 | Volume: 128 | Issue: 22 | Pages: 1192-1192

10.1182/blood.v128.22.1192.1192

Abstract Background: Race/ethnicity is associated with disparate incidence and outcomes in MM, as seen in population-based studies. Their effect on outcomes has not been reported in prospective studies. Obesity is the most consistently associated modifiable risk factor for MM and is influenced by race/ethnicity but its association with outcomes has not been explored. We analyzed patient-level data from published ECOG-ACRIN/SWOG clinical trials in newly diagnosed MM (NDMM) patients (pts) to explore the interplay of race/ethnicity, obesity and outcomes. Methods: Pooled data from 9 ECOG-ACRIN/SWOG clinical trials (E1A06, E4A03, E1A00, E2A02, E5A93, E9486, S0204, S0232, S9321) in NDMM (1988-2011) were analyzed. Pts were divided by race: White (W), African-American (AA), other (O); race/ethnicity: Hispanic (H), non-Hispanic White (NHW), non-Hispanic AA (NHAA), non-Hispanic other (NHO); and body mass index (BMI): <25, 25-29.9, ≥30. Associations between these and baseline pt/disease characteristics were assessed using chi-square (categorical) and Wilcoxon rank sum (continuous) tests. Survival distributions were estimated with Kaplan-Meier method and compared between groups using log-rank test. Cox proportional hazards regression was used to estimate hazard ratios in univariate and multivariate models. Time to event data was censored at 6 yrs. Results: Pt distribution by race, race/ethnicity and BMI is shown in Table 1. Race: AA were younger than W (median 59 vs 62 yr), had significantly more females (48% vs 40%; p=0.001) and had a smaller proportion of pts ≥70 yr (18% vs 26%; p<0.001). Median BMI was highest in AA (27.2) and lowest in O (24) (p=0.001) but not significantly different categorically between W and AA only (p=0.908). AA had significantly more pts with hemoglobin (Hb) ≤10 g/dL than W (55% vs 36%; p<0.001). Median creatinine (Cr) was 1.3 mg/dL in O and 1.1 mg/dL in W (p=0.03). There were no differences by race for ECOG performance status (PS), MM stage, lytic lesions, paraprotein subtype, serum calcium (Ca) or β2-microglobulin (β2M). Enrollment to clinical trials over years was significantly different by race (p=0.009). The only study design showing different enrollment by race was with/out stem cell transplant (SCT) (p=0.03; 37% of AA vs 31% of W got SCT trials). Race/Ethnicity: NHO were the youngest (median 58 yr) and NHW the oldest (median 62 yr) subgroup (p<0.001). NHAA had the highest proportion of pts with BMI ≥30 (16%) and NHO the lowest (7%) (p=0.018). H had the smallest proportion of females (33%) while NHO had the largest (54%) (p=0.002). H had the highest number of pts ≥70 yr (28%) and NHAA the smallest (18%) (p=0.003). Anemia rates were significantly different (p<0.001) with Hb ≤10 g/dL in 36% NHW vs 56% in NHAA. No significant differences were seen for PS, MM stage, lytic lesions, paraprotein subtype or other lab parameters. H and NHAA were enrolled in larger numbers in 1992-2011 rather than prior or later years (p<0.001). Among the subgroups, H had largest proportion of patients (75%) on trials without novel agent vs 61.5% for NHW (p=0.047). NHAA had the highest proportion of patients on trials with SCT (38%) while NHO had the smallest (27.3%) (p=0.034). BMI: By gender, 30% of males and 39% of females having BMI <25 (p<0.001). BMI <25 had the highest proportion of pts with ISS stage III (31%) vs 21.5% for ≥30 (p=0.001). A similar trend was seen for DS stage (p=0.005). 64% of ≥30 pts had Hb >10 while 51% of <25 did (p=0.003). There was significant difference in continuous Cr distribution by BMI (p=0.004). Efficacy analysis did not show any significant difference in response rate by race (p=0.132), race/ethnicity (p=0.286) or BMI (p=0.896). In univariate/multivariate analysis, significantly worse overall survival (OS) was seen in males, age ≥70 yr, ECOG PS >0, ISS and DS stage III, presence of lytic lesions, Cr ≥2 mg/dL, Ca >12 mg/dL, Hb ≤10 g/dL. No significant difference was seen in OS or progression free survival by race, race/ethnicity or BMI (Figure 1). Conclusions: Significant differences exist in demographic and clinical characteristics of NDMM pts by race/ethnicity. Median OS was significantly associated with these characteristics but not with race/ethnicity itself. Observed racial/ethnic disparity in outcomes for MM pts may be overcome by access to comparable therapeutic options as seen in clinical trials. Obesity, while associated with MM incidence, does not seem to influence outcomes. Figure 1 Figure 1. Disclosures Ailawadhi: Pharmacyclics: Consultancy; Novartis: Consultancy; Amgen Inc: Consultancy; Takeda Oncology: Consultancy. Stewart:Janssen Pharmaceuticals: Consultancy; Takeda Oncology: Consultancy; Celgene: Consultancy; Bristol Myers Squibb: Consultancy. Hussein:Celgene: Employment. Zonder:Takeda: Consultancy, Honoraria; Bristol Myers Squibb: Consultancy, Honoraria; Seattle Genetics: Consultancy, Honoraria; Celgene: Consultancy, Honoraria, Research Funding; Janssen: Consultancy, Honoraria; Pharmacyclics: Other: DSMC membership; Prothena: Consultancy, Honoraria. Barlogie:Mount Sinai Hospital: Employment.
Comprehensive Investigation of White Blood Cell and Gene Expression Profiles As Risk Factors for Multiple Myeloma in African Americans

Blood | November 14, 2019 | Volume: 134 | Issue: Supplement_1 | Pages: 4379-4379

10.1182/blood-2019-129298

Multiple myeloma (MM) is a neoplasm thought to arise from a damaged germinal center B-cell that progresses to a plasma cell clone arising in bone marrow. MM comprises 20% of all hematologic cancer deaths. Persons of African ancestry (AA) have a 1.5 to 2-fold higher risk compared to individuals of European ancestry (EA). Genetically driven differences in hematopoiesis may lead to variation in the levels white blood cell (WBC) subsets which could, in turn, be associated with MM etiology. There are differences in genetic determinants of WBC traits between EA and AA populations, with possible implications for the racial disparity in risk. We tested the above hypothesis using Mendelian randomization (MR), an approach that leverages genetic determinants of specific traits (i.e. WBC counts) to estimate their effects on the risk of an outcome; and a transcriptome-wide association study (TWAS), which utilizes genetic predictors of gene expression to identify susceptibility genes. These analytic approaches were applied to data from the African American Multiple Myeloma Study (AAMMS) consisting of 1813 cases and 8871 AA cancer-free controls to examine how differences in heritable WBC gene expression profiles influence MM risk. Genetic determinants of variation in WBC subsets in AA were obtained from the literature and supplemented with new genome-wide association findings in AA subjects from the UK Biobank cohort (n=6108). Odds ratios (OR) for MM per 1 standard deviation (SD) increase in each WBC phenotype were estimated using independent (linkage disequilibrium (LD) r2<0.10) variants with P<10-6 as genetic instruments. Analyses based on variants associated with WBC traits in AA populations did not identify any statistically-significant associations between MM risk and WBC overall (p=0.81, using 15 SNPs) or subsets (lymphocytes, monocytes, eosinophils, neutrophils and basophils, p>0.05 for each). However, when we applied genetic determinants of WBC identified in 330,000 cancer-free EA UK Biobank participants (P<10-8, replication P<0.05, LD r2<0.05), a statistically significant inverse relationship emerged between increasing lymphocyte counts and MM risk (OR=0.80, 95% CI: 0.66-0.97, p=0.02, using 385 SNPs), as well as increasing basophil counts (OR=0.63, 95% CI: 0.41-0.96, p=0.03, using 140 SNPs). Next, we examined the association between WBC gene expression profiles and MM risk in AAMMS data. We applied published and validated ancestry-specific models developed using the PrediXcan approach, which leverage germline genetic and transcriptomic data from the Multi-Ethnic Study of Atherosclerosis (MESA) (Mogil et al. PMID: 30096133). The primary TWAS used gene expression models trained in AA subjects (n=233), with sensitivity analyses using models developed in AA and Hispanic subjects (n=585). The TWAS significance threshold was based on the number of genes with significant germline prediction models (p<0.05 and R2 ≥0.05) in AA, corresponding to P < 0.05/2700 = 1.85×10-5. The expression of two genes was significantly associated with MM risk: KANK1at 9p24.3 (P = 1.01×10-5) and DNAJC27at 2p23.3 (P = 1.56×10-5). KANK1is a candidate tumor suppressor gene for renal cell carcinoma and has recently been associated with MM risk in AA [Du, Blood 2017 130:3058]. Here we provide additional evidence for its role in MM etiology via gene expression-mediated mechanisms. DNAJC27 (previously known as RBJ) is a novel MM risk gene linked to constitutive activation of ERK in solid tumors. We also identified two suggestively associated genes: PRR14 (P = 1.34×10-4; combined AA-Hispanic sample: P = 1.56×10-6), which has been linked to MM risk in EA populations, and PARP16 (P = 9.46×10-5). To our knowledge this is the first study to comprehensively examine variation in WBC traits and gene expression profiles with respect to MM risk in AA. Our TWAS analysis leveraged data from the largest collection of genetic and gene expression data in AA, enabling ancestry-matched inference and identification of two novel risk genes. Although the limited availability of genetic instruments for WBC limited the power of MR analysis, findings using variants identified in European populations may offer some insight into trans-ethnic etiologic pathways and contribute to risk stratification strategies using genetic and blood cell count biomarkers. Future studies, particularly with MGUS-free controls, are needed to validate these results. Disclosures Song: Millennium Pharmaceuticals Inc: Employment. Rand:Ancestry.com: Employment. Ailawadhi:Cellectar: Research Funding; Janssen: Consultancy, Research Funding; Celgene: Consultancy; Pharmacyclics: Research Funding; Amgen: Consultancy, Research Funding; Takeda: Consultancy. Nooka:Takeda: Honoraria, Other: advisory board participation; Janssen: Honoraria, Other: advisory board participation; GSK: Honoraria, Other: advisory board participation; Spectrum pharmaceuticals: Honoraria, Other: advisory board participation; Adaptive technologies: Honoraria, Other: advisory board participation; Amgen: Honoraria, Other: advisory board participation; Celgene: Honoraria, Other: advisory board participation; BMS: Honoraria, Other: advisory board participation. Singhal:Bureau of Millennium/Takeda, Celgene, Janssen, Celgene, Bristol-Myers Squibb and Bluebird: Speakers Bureau. van Rhee:Takeda: Consultancy; Sanofi Genzyme: Consultancy; Castleman Disease Collaborative Network: Consultancy; EUSA: Consultancy; Adicet Bio: Consultancy; Kite Pharma: Consultancy; Karyopharm Therapeutics: Consultancy. Mehta:Millennium/Takeda, Celgene; stock in Celgene, Bristol-Myers Squibb and Bluebird: Speakers Bureau. Wolf:Takeda: Consultancy; Celgene: Consultancy; Novartis: Consultancy; Janssen: Consultancy; Amgen: Consultancy. Martin:Roche and Juno: Consultancy; Amgen, Sanofi, Seattle Genetics: Research Funding. Fiala:Incyte: Research Funding. Terebelo:Jannsen: Speakers Bureau; Celgene: Honoraria; Newland Medical Asociates: Employment. Anderson:Bristol-Myers Squibb: Other: Scientific Founder; Oncopep: Other: Scientific Founder; Amgen: Consultancy, Speakers Bureau; Janssen: Consultancy, Speakers Bureau; Takeda: Consultancy, Speakers Bureau; Celgene: Consultancy, Speakers Bureau; Sanofi-Aventis: Other: Advisory Board. Vij:Bristol-Myers Squibb: Honoraria, Research Funding; Celgene: Honoraria, Research Funding; Genentech: Honoraria; Janssen: Honoraria; Karyopharm: Honoraria; Sanofi: Honoraria; Takeda: Honoraria, Research Funding. Bernal-Mizrachi:TAKEDA: Research Funding; Kodikas Therapeutic Solutions, Inc: Equity Ownership; Winship Cancer Institute: Employment, Patents & Royalties. Morgan:Amgen, Roche, Abbvie, Takeda, Celgene, Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees; Celgene: Other: research grant, Research Funding. Zonder:Celgene Corporation: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Takeda: Membership on an entity's Board of Directors or advisory committees; Amgen: Consultancy, Membership on an entity's Board of Directors or advisory committees; Intellia: Consultancy, Membership on an entity's Board of Directors or advisory committees; Caelum: Consultancy, Membership on an entity's Board of Directors or advisory committees; Alnylam: Consultancy, Membership on an entity's Board of Directors or advisory committees; BMS: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Janssen: Consultancy, Membership on an entity's Board of Directors or advisory committees; Oncopeptides: Consultancy, Membership on an entity's Board of Directors or advisory committees. Huff:Member of Safety Monitoring Board for Johnson and Johnson: Membership on an entity's Board of Directors or advisory committees; Karyopharm, Sanofi, MiDiagnostics: Consultancy. Lonial:Karyopharm: Consultancy; Takeda: Consultancy, Research Funding; Amgen: Consultancy; BMS: Consultancy; Janssen: Consultancy, Research Funding; GSK: Consultancy; Celgene Corporation: Consultancy, Research Funding; Genentech: Consultancy. Orlowski:Poseida Therapeutics, Inc.: Research Funding.