Kyle, Robert A.

e20520 Background: Cytogenetic abnormalities detected by FISH are found in the majority of multiple myeloma (MM) patients. Although their prognostic value has been studied extensively, less is known about their association with disease characteristics and treatment response. Methods: To address these questions, we designed a retrospective study including 2031 Mayo Clinic patients diagnosed with MM from 2004 to 2018. We compared baseline characteristics and treatment outcomes between primary cytogenetic groups: t(11;14), t(4;14), t(14;16), (14;20), t(6;14), unknown IgH translocation/del and trisomy (without IgH translocation). These included 373, 177, 78, 20, 18, 228 and 791 patients respectively. Kruskal-Wallis and Fisher’s exact tests were used for categorical and continuous variables respectively. Time to next treatment (TTNT) was estimated using Kaplan-Meier method and compared using Log-Rank test. Results: t(4;14), t(14;16), t(6;14) and t(14;20) groups were associated with hemoglobin < 10 g/dL, beta2microglobulin > 5.5 µg/ml, ISS stage 3 and ≥50% bone marrow plasma cells. The latter 3 groups were also associated with renal dysfunction (Cr ≥2 mg/dL) and higher urinary monoclonal protein. t(4;14) was associated with IgA isotype, serum monoclonal protein ≥1g/dL and plasma cell labeling index ≥1%. Light chain myeloma was more prevalent in patients with t(11;14). Overall response rate (ORR) to proteasome inhibitor (PI) induction was higher for those with IgH translocations (any) compared to trisomies (85% vs 77% P = 0.02), while ORR was higher for those with trisomies with immunomodulatory drug (IMiD) induction (90% vs 78% P < 0.01). The rate of ≥ very good partial response was higher for patients with high risk IgH translocations [t(4;14), t(14;16) or t(14;20)] compared to standard risk with PI-IMiD combination treatment (88% vs 65% P < 0.01). Otherwise, response rates did not differ between these 2 groups. TTNT was longer in patients with trisomies compared to those with IgH translocation with IMiD or PI-IMiD treatments (32.2 vs 19 and 44 vs 27.4 months, respectively P < 0.01). For all cytogenetic groups, better treatment responses and longer TTNT were seen with PI-IMiD combinations compared to other treatments. Conclusions: t(4;14), t(14;16), t(6;14), and t(14;20) are associated with high risk disease characteristics. Patients with IgH translocations may have better response to PI induction compared to those with trisomies, while those with trisomies may have better response to IMiD treatment, with best outcomes for both seen with PI-IMiD combinations.

e20510 Background: pPCL is a rare and aggressive form of multiple myeloma (MM) with dismal survival outcomes compared to the remainder of MM patients. Several studies have validated the optimal cutoff for defining pPCL to be >5% circulating plasma cells (cPCs) on a peripheral blood smear due to equally poor outcomes in this less restrictive cohort. We evaluated the clinical outcomes and cytogenetic features of patients diagnosed with pPCL at our institution that were treated with novel agent induction therapies. Methods: We evaluated patients with pPCL diagnosed between 2000 – 2018 (using the 5% cut off) at Mayo Clinic, Minnesota. Data was extracted from a prospectively maintained database and from the review of electronic medical records. Patients were categorized as having high risk (HR) cytogenetics if any of the following abnormalities were present: del 17p, t(4;14), t(14;16) or t(14;20). Chi-square tests and Fisher exact tests were used to compare differences between sub-groups. Survival analysis was performed by the Kaplan-Meier method and differences assessed using the log rank test. Results: This cohort consisted of 67 patients with pPCL with a median age of 62 years (range: 34-91) of which 33 (46%) were male. The median follow up was 46 months (95% CI: 41 – 90). The median bone marrow plasma cell involvement was 84% (Range: 10 – 100) and the median cPCs percentage on the peripheral blood was 23% (range: 5 - 93). Data on primary cytogenetic abnormalities were available in 60 (85%) patients and the distribution was as follows: t(11;14) – 27 (45%), t(4;14) – 5 (8%), t(14;16) – 8 (13%), t(14;20)- 3(5%) and del 17p- 15(25%). All patients received novel agent induction therapy with 36 (54%) having received autologous stem cell transplant and 4 undergoing an allogeneic stem cell transplant. The median time to next therapy (TTNT) and overall survival (OS) for all patients was 13 months (95% CI: 9 – 17) and 24 months (95% CI: 19 – 40) respectively; 16 months and 51 months for standard risk (SR) vs. 10 months and 19 months for HR (P = 0.005 for OS), when stratified by cytogenetic risk. There were only 17 (31%) patients who were alive for ≥48 months since diagnosis (i.e. twice the median OS of this cohort); The absence of high risk cytogenetics (P = 0.049) and non-elevated LDH level (P = 0.047) at diagnosis predicted for achieving this survival goal. Conclusions: The outcomes of patients diagnosed with pPCL remain poor despite the use of novel agent induction therapy. However, some patients appear to do better than expected and this phenomenon may be influenced by the presence of HR cytogenetics.

8550 Background: Waldenström Macroglobulinemia (WM) is a rare lymphoplasmacytic malignancy characterized by the presence of a recurrent point mutation in the MYD88 gene (MYD88L265P) in 80-95% of cases. Patients with MYD88WT genotype comprise a small subset that responds poorly to ibrutinib and other Bruton tyrosine kinase inhibitors. We examined the characteristics and outcome of WM patients with MYD88WT genotype predominantly treated with non-BTK inhibitor based therapies. Methods: Patients with a diagnosis of WM seen at Mayo Clinic, Rochester, between 1996 and 2018 were included. Their characteristics and outcomes were assessed from the time of active disease. Marrow MYD88 genotyping was assessed with an allele specific PCR assay (analytic sensitivity 1%). Categorical and continuous variables were compared using Chi square and Wilcoxon tests, respectively. Time-to-event analyses were performed using Kaplan Meier test. Results: Of 986 patients with active WM, MYD88 genotype data were available in 331 (34 %) patients; 72 (22%) and 260 (78%) patients harbored MYD88WT and MYD88L265P genotypes, respectively. The median follow-up was 5.8 years (95% CI: 5.0-6.5 years) from active WM; 6 years MYD88WT vs 5.4 years for MYD88L265P cohort. Median age was 63 years and 66 years in the MYD88WT and MYD88L265P cohorts, respectively (p = 0.07) with 46% and 53% patients being ≥65 years of age, respectively (p = 0.36). Pre-treatment marrow lymphoplasmacytic (LPL) infiltrate (median 40% for MYD88WT vs 60% for MYD88L265P; p = 0.001) and beta-2 microglobulin (median 3 µg/mL for MYD88WT vs 3.9 µg/mL for MYD88L265P; p = 0.02) were lower in the MYD88WT compared to the MYD88L265P cohort; other laboratory parameters at active disease were comparable. Per IPSSWM prognostic criteria, MYD88WT had fewer patients in the high risk group (18% for MYD88WT vs 42% MYD88L265P; p = 0.03). Patients with MYD88WT had higher likelihood of histological transformation [18% for MYD88WT vs 4% for MYD88L265P; odds ratio 5.8 (95% CI: 2.5-13.5; p < 0.0001)]. Among patients with treatment data available, only 35 (11%) patients received ibrutinib. The 5-year overall survival (OS) from active disease was comparable (85% in MYD88WT vs 82% in MYD88L265P cohort; p = 0.7). Conclusions: MYD88WT genotype in WM is associated with lower marrow LPL infiltration, lower likelihood of high-risk IPSSWM categorization and a higher likelihood of histological transformation in comparison to MYD88L265P mutant subpopulation. MYD88 genotype does not affect the OS from active disease in predominantly non-BTK inhibitor treated patients.

AbstractMetaphase cytogenetic abnormalities, plasma cell proliferation index (PCPro), and gain 1q by fluorescence in situ hybridization (FISH) are associated with inferior survival in newly diagnosed multiple myeloma (MM) treated with novel agents; however, their role in risk stratification is unclear in the era of the revised International Staging System (R-ISS). The objective of this study was to determine if these predictors improve risk stratification in newly diagnosed MM when accounting for R-ISS and age. We studied a retrospective cohort of 483 patients with newly diagnosed MM treated with proteasome inhibitors and/or immunomodulators. On multivariable analysis, R-ISS, age, metaphase cytogenetic abnormalities (both in aggregate and for specific abnormalities), PCPro, and FISH gain 1q were associated with inferior progression-free (PFS) and overall survival (OS). We devised a risk scoring system based on hazard ratios from multivariable analyses and assigned patients to low-, intermediate-, and high-risk groups based on their cumulative scores. The addition of metaphase cytogenetic abnormalities, PCPro, and FISH gain 1q to a risk scoring system accounting for R-ISS and age did not improve risk discrimination of Kaplan-Meier estimates for PFS or OS. Moreover, they did not improve prognostic performance when evaluated by Uno’s censoring-adjusted C-statistic. Lastly, we performed a paired analysis of metaphase cytogenetic and interphase FISH abnormalities, which revealed the former to be insensitive for the detection of prognostic chromosomal abnormalities. Ultimately, metaphase cytogenetics lack sensitivity for important chromosomal aberrations and, along with PCPro and FISH gain 1q, do not improve risk stratification in MM when accounting for R-ISS and age.

Abstract Introduction: The immunoglobulin free light chain (FLC) is the precursor protein of amyloid in primary systemic amyloidosis (AL). Historically, the ability to monitor the amyloid protein precursor has been crude. There is now a test that reproducibly measures serum levels of FLC. We evaluated the utility of this assay in patients with AL undergoing peripheral blood stem cell transplant (PBSCT). Methods: Between March 1, 1996 and July 31, 2004, 98 patients with AL undergoing PBSCT had serial FLC measurements performed either prospectively or on stored sera. Patients who died before their 100 day evaluation were excluded because response could not be estimated. FLC levels were performed using Freelite™ reagents on a Dade-Behring Nephelometer. In order to pool the data of the monoclonal kappa and lambda patients, the clonal free light chain was considered the involved] immunoglobulin free light chain for the purpose of these analyses and is henceforth referred to as FLC. The prognostic effects of the initial concentration and the extent of reduction of monoclonal FLC on survival were evaluated. Results: Pre-transplant, 94% of patients had an abnormal FLC ratio, with a median involved FLC of 152 mg/L [15.2 mg/dL]. Only 14% of 98 patients had a “measurable” serum M-spike (i.e. ≥ 10 g/L [1 g/dL]) on electrophoresis with a median of 1 g/L [0.1 g/dL]. Ten patients have died of their disease during a median follow-up time of 19.5 months, range 3.3 to 103 months. The 2- year and 4-year estimated survivals are 92% and 76%, respectively. Using the 75th percentile value of pre-PBSCT FLC (382 mg/L [38.2 g/dL]) as a grouping variable, there was a significantly higher risk of death 5.4 (95% confidence interval 1.5–19.3) in the patient quartile with the highest baseline FLC. Baseline FLC correlated with serum cardiac troponin T levels (rho 0.51, p&lt;0.0001), suggesting that high FLC levels are associated with more advanced disease. After PBSCT, the median percent reduction of FLC was 81%. The percent FLC reduction did not predict for survival, but the absolute level of FLC achieved after therapy did. The hazard ratio for death for not achieving a post-transplant FLC of 20 mg/L [2 mg/dL] post-transplant was 5.1 (95% confidence interval 1.1–24.1). Of 91 patients evaluable for complete response by EBMT criteria, 45 had a complete hematological response. Sixty-five percent of the patients achieving a FLC level of less than 20 mg/L [2 mg/dL] also had a complete hematologic response. Free light chain response as defined by a post transplant FLC level 20mg/L [2 mg/dL] or lower was a more powerful predictor of survival than complete hematologic response, as defined by the EBMT multiple myeloma criteria. Post-PBSCT FLC level only weakly predicted for organ response, but median follow-up for surviving patients is relatively short at 19.6 months. Conclusion: FLC measurements both pre- and post-PBSCT are important predictors of patient outcome.

Abstract Purpose: Lenalidomide (CC-5013) is an analogue of thalidomide and a lead clinical compound in a new group of drugs called IMiDS® which have immunomodulatory properties. Lenalidomide has shown promising results in relapsed refractory myeloma. It has a markedly different side-effect profile compared to thalidomide, with significantly fewer non- hematologic adverse events; myelosuppression, especially neutropenia, is the most common toxicity. We report the results of a phase II trial using the combination of lenalidomide plus dexamethasone (Rev/Dex) as initial therapy for newly diagnosed multiple myeloma. Patients and Methods: 34 patients (23 male and 11 female) were enrolled. Lenalidomide was given orally 25 mg daily on days 1–21 of a 28-day cycle. Dexamethasone was given orally at a dose of 40 mg daily on days 1–4, 9–12, 17–20 of each cycle. Patients were allowed to go off treatment after 4 cycles of therapy to pursue stem cell transplantation, but treatment beyond four cycles was permitted at the physician’s discretion. For patients continuing therapy beyond 4 months, the dose of dexamethasone was reduced to 40 mg on days 1–4 of each cycle. Objective response was defined as a decrease in serum monoclonal (M) protein by 50% or greater and a decrease in urine M protein by at least 90% or to a level less than 200 mg/24 hours, confirmed by two consecutive determinations at least 4 weeks apart. Sub-classification as very good partial response (VGPR) required in addition to criteria for partial response, &gt;=90% reduction in serum M protein, 24 hour urine M protein less than or equal to 100 mg, and 5% or fewer plasma cells on bone marrow examination. All patients received aspirin (81 mg or 325 mg daily) as prophylaxis against DVT. Results: The median age was 64 years (range, 32–78). All patients were evaluable for response and toxicity. Thirty-one of 34 patients (91%) achieved an objective response to therapy, including 2 patients (6%) achieving a complete response (CR) and 11 patients (32%) achieving very good partial response. Of the 3 patients not achieving an objective response, two met criteria for minor response and one had stable disease. Responses were rapid; the median time to response was 1 month. Adequate stem cells (&gt;3.0 million CD34 cells/kg body weight) were obtained in all patients who proceeded to autologous stem cell transplantation. Forty-seven percent of patients experienced grade 3 or higher non-hematologic toxicity, most commonly fatigue (15%), muscle weakness (6%), anxiety (6%), pneumonitis (6%) and rash (6%). One patient died on study, and this was attributed to infection unrelated to therapy; the patient had stopped all therapy for over a month before the fatal infection occurred. One patient developed a pulmonary embolism, but recovered with therapy; no other patient developed deep vein thrombosis or pulmonary embolism. Conclusion: Rev/Dex is highly active and well tolerated in the treatment of newly diagnosed multiple myeloma with overall responses in over 90% of patients including complete and very good partial responses in 38%. Two large cooperative group trials are currently testing Rev/Dex as initial therapy for multiple myeloma in the United States.

Abstract Background: Viral vectors based on the Edmonston strain of measles virus (MV-Edm) selectively destroy all tumor cell lines tested in vitro. The oncolytic activity of the virus is enhanced by expression of the thyroidal sodium iodide symporter (MV-NIS) that allows selective 131I uptake by infected tumor cells and eliminates myeloma tumor xenografts that are resistant to the parent virus. MV-NIS is being considered for therapy of patients with relapsed or refractory multiple myeloma. Advanced myeloma is associated with significant immunosuppression with the potential risk of uncontrolled virus proliferation. The number of agents with activity against MV is limited. Low energy (Auger) electrons have a short path length and selectively damage cells in which the isotope decays. Thus, we hypothesized that the Auger electron emitting isotope 125I, selectively taken up by cells expressing NIS, can be used to control viral proliferation. Methods: A replication competent MV that expressed both a soluble form of carcinoembryonic antigen (CEA) and NIS (MV-NICE) was rescued and characterized. Cells were infected with MV-NICE or control vectors and exposed to 125I with appropriate controls. CEA expression and viral titers were determined at different time points. The role of free radical generation on virus replication was explored. In vivo control of MV-NICE replication with 125I was attempted. Results: MV-NICE replication in vitro is inhibited by the selective uptake of 125I by cells expressing NIS. Extracellular decay of the isotope has no effect on virus proliferation. Auger electron damage is in part mediated by free radicals and abrogated by glutathione. In myeloma xenografts, control of MV-NICE with 125I was not possible under the conditions of the experiment. Conclusion: MV-NICE does not replicate faster in the presence of radiation under our experimental conditions. Auger electron emitting isotopes effectively stop propagation of MV vectors expressing NIS in vitro. Additional work is necessary to translate these observations in vivo.

Abstract Background: Monoclonal gammopathy of undetermined significance (MGUS) is a premalignant plasma cell disorder that carries a 1% per year risk of progression to multiple myeloma (MM) or related malignancy. The prevalence and natural history of MGUS, in which by definition intact immunoglobulin heavy chain (IgH) is expressed, has been well described. However, up to 20% of myeloma (MM) is characterized by complete lack of IgH expression (Light-chain MM); the prevalence of a corresponding precursor entity, light chain MGUS (LC-MGUS) has not been determined. We report the first prevalence estimates of LC-MGUS in the general population from a large, well-defined geographic population using modern laboratory techniques. Methods: The cohort for this study was derived from one previously assembled by us to estimate the prevalence of MGUS (N Engl J Med2006;354:1362-9). The original cohort used to estimate the prevalence of MGUS consisted of 21,463 of the 28,038 enumerated residents aged 50 or over of Olmsted County Minnesota as of January 1, 1995. The sensitive serum free light chain (FLC) assay (The Binding Site Limited, Birmingham, U.K.) was performed on stored serum samples from these 21,463 persons. IgH expression was determined by immunofixation on all FLC results that had an abnormal kappa/lambda ratio (&lt;0.26 or &gt;1.65). LC-MGUS was defined as the presence of an abnormal FLC ratio and a negative immunofixation for IgH expression. Results: Adequate stored serum samples were available in 20,733 (97%) of the 21,463 persons. To date, the FLC assay has been performed and results were available for analysis on samples from 16,637 persons. An abnormal FLC ratio was observed in 572 persons. IgH expression was detected in 255 of these cases on immunofixation; these persons are considered as having MGUS, and were excluded from the estimation of LC-MGUS prevalence. This resulted in 317 persons out of 16,637 who had an abnormal FLC ratio without evidence of IgH expression, resulting in an estimated prevalence of LC- MGUS of 2%. Of the 317 cases of LC-MGUS identified in this study, 217 were kappa and 100 were lambda; in 35 cases the presence of the corresponding monoclonal light chain was apparent on immunofixation. The median age of the cohort of LC-MGUS was 62 years; males=151, females =166. The involved FLC level ranged from 0.118–270.0 mg/dL. The FLC ratio ranged from 0.014–0.253 (lambda) and 1.67–511.01 (kappa). So far, progression to multiple myeloma has occurred in 4 patients, a rate much higher than what is expected based on the prevalence of myeloma in the general population. Two additional patients have developed CLL. Conclusions: LC-MGUS is prevalent in 2% of the general population aged 50 years of age or older. The natural history of this disorder needs to be determined.

Abstract Due to the diagnostic sensitivity of serum free light chain quantitation for monoclonal light chain diseases, it has been suggested that urine assays no longer need be performed as part of the diagnostic algorithm for monoclonal proteins. We reviewed our experience to determine the relative diagnostic contribution of urine assays. Methods: Patients with a monoclonal gammopathy and monoclonal urinary protein at initial diagnosis who also had a serum immunofixation and serum free light chain quantitation within 30 days of diagnosis were identified (n = 428). The laboratory results for serum protein electrophoresis, serum immunofixation, serum free light chain, urine protein electrophoresis, and urine immunofixation were reviewed. Results: The patients in this cohort had diagnoses of multiple myeloma, primary amyloid, monoclonal gammopathy of undetermined significance, smoldering multiple myeloma, solitary plasmacytomas, and other less frequently detected monoclonal gammopathies. By definition of the cohort, all 428 had a monoclonal urine protein. 86% had an abnormal serum free light chain K/L ratio, 81% had an abnormal serum protein electrophoresis, and 94% had an abnormal serum immunofixation. In only 2 patients, however, were all 3 serum assays normal. Both of these were patients with monoclonal gammopathy of undetermined significance (idiopathic Bence Jones proteinuria). Conclusion: Discontinuation of urine studies and reliance on a diagnostic algorithm using solely serum studies (protein electrophoresis, immunofixation, and free light chain quantitation), missed 2 of the 428 monoclonal gammopathies (0.5 %) with urinary monoclonal proteins, and these 2 cases required no medical intervention.

Abstract Background: The measurement of monoclonal (M) protein in the serum and urine is critical for response assessment and disease evaluation in patients with multiple myeloma (MM). The serum free light chain (FLC) assay offers a new and sensitive method of assessing response to therapy. An important question that has not been adequately addressed is the correlation between 24 hour urine M protein levels and serum FLC measurements, and the extent to which response to therapy estimated using the FLC assay correlates with that assessed using the 24 hour urine M protein level. Methods: A total of 2194 sets of data, with simultaneous UPEP and serum FLC measurement, were studied. These included 752 unique patients, with individual patients having 1–23 paired assessments over time. FLC estimation was carried out using the serum FLC assay (Freelite; The Binding Site Limited, UK) performed on a Dade-Behring Nephelometer. Based on the established reference range, kappa/lambda FLC ratio &lt;0.26 or &gt;1.65 were defined as abnormal indicating the presence of monoclonal lambda and kappa FLC, respectively. The monoclonal light chain isotype was considered the involved FLC isotype, and the opposite light chain type as the uninvolved FLC type. The Urine M protein by UPEP was compared to the serum levels of the involved light chain using Spearman Rank Correlation. For comparisons in individual patients over time, those with at least 10 measurements each were studied. Results: The median involved FLC level in patients with an undetectable urine M protein was 2.3 mg/dl compared to 32.2 mg/dL among those with a detectable urine M protein (P&lt;0.001). Among the 1676 points with an abnormal FLC ratio, only 75% had an M protein detected in the urine, P &lt; 0.001. Conversely, among patients with a positive urine M-protein, 91% had an abnormal FLC ratio. When all the 2194 data points were considered together, there was a significant correlation between the urine M protein level and the FLC levels (FLC level calculated as the difference between involved and uninvolved levels), rho=0.763, P &lt; 0.001. The correlation did not change when patients with a serum creatinine of over 2.5 were excluded. The correlation between FLC levels and urinary M protein can be affected by several factors such as renal function that will differ across patients. Therefore, we examined whether the correlation between the two variables is stronger when the variations introduced by inter-patient differences in the relationship between the two variables are eliminated. In order to do this, we studied individual patients on whom multiple data points over time were available. One patient who had the maximum number of paired assessments (23 pairs) of serum FLC level and urinary M protein; the correlation between the two variables over time was highly significant, rho 0.981, p&lt;0.001. Similarly 26 other patients who had measurable urine M protein levels in whom 10 nor more paired observations over time were available, also showed significant correlations, rho, range 0.726–0.981, p&lt;0.01. Conclusion: There is a significant correlation between urine M-protein and serum free light chain across patients and the correlation is stronger in individual patients in whom the effect of inter-patient variation in other confounding factors can be eliminated. These data if confirmed in a clinical trial setting would support the use of serum FLC levels instead of urinary M protein measurements to assess response to therapy.