Symptomatic WM Research Articles

Determination of MYD88 and CXCR4 mutation for clinical detection and their significance in Waldenström macroglobulinemia.

This study aims to explore the incidence and clinical features of MYD88 and CXCR4 mutations in patients with Waldenström macroglobulinemia (WM) and determine the optimal method for routine clinical practice. Additionally, we seek to evaluate the prognostic significance of these features across various therapeutic backgrounds [cytotoxic group, the Rituximab/Bortezomib-based group, and the Bruton's tyrosine kinase inhibitor (BTKi) group]. 385 symptomatic WM patients were analyzed for MYD88 and CXCR4 mutations using Sanger sequencing, next-generation sequencing (NGS), allele-specific quantitative polymerase chain reaction (AS-PCR), and/or droplet digital PCR (ddPCR). The overall MYD88 mutation rate was 87.8%, relatively lower than that in Western cohort. Both AS-PCR and ddPCR demonstrated high sensitivity in unsorted samples, detecting 98.5% and 97.7% of mutations, respectively, including those with low tumor burdens. The total CXCR4 mutation rate was 30.9%, with NGS exhibiting the highest sensitivity of 78.0%. CXCR4 mutation was significantly linked to shorter OS only within the BTKi treatment group. The multivariate analysis indicated that MYD88 and CXCR4 mutations were not independent prognostic factors in the non-BTKi group when considering IPSSWM clinical staging. However, in the BTKi treatment group, these mutations emerged as independent adverse prognostic factors, overshadowing the prognostic significance of IPSSWM classification (MYD88: HR=0.229, P=0.030; CXCR4: HR=3.349, P=0.012). Testing for MYD88 mutations using AS-PCR or ddPCR in unsorted samples is viable for routine clinical practice. Under BTKi treatment, MYD88 and CXCR4 mutations hold greater prognostic importance than IPSSWM staging in WM.

Simplified Risk Stratification Model for Patients With Waldenström Macroglobulinemia.

Patients with Waldenström macroglobulinemia (WM) have disparate outcomes. Newer therapies have emerged since the development of International Prognostic Scoring System, and MYD88L265P mutation is now frequently assessed at diagnosis, warranting reexamination of the prognostic parameters. We reviewed records of 889 treatment-naïve patients with active WM, consecutively seen between January 01, 1996, and December 31, 2017, to identify clinical predictors of overall survival (OS) in univariate analyses. Patients with complete data for the parameters significant on the univariate analyses (n = 341) were included in a multivariable analysis to derive a prognostic model, subsequently validated in a multi-institutional cohort. In the derivation cohort (n = 341), age (hazard ratio [HR], 1.9 [95% CI, 1.2 to 2.1]; P = .0009), serum lactate dehydrogenase (LDH) above upper limit of normal (HR, 2.3 [95% CI, 1.3 to 4.5]; P = .007), and serum albumin <3.5 g/dL (HR, 1.5 [95% CI, 0.99 to 2.3]; P = .056) were independently prognostic. By assigning a score of 1 point each to albumin <3.5 g/dL (HR, 1.5) and age 66-75 years (HR 1.4) and 2 points for age >75 years (HR, 2.6) or elevated LDH (HR, 2.3), four groups with distinct outcomes were observed on the basis of the composite scores. Five-year OS was 93% for the low-risk (score 0), 82% for low-intermediate risk (score 1), 69% for intermediate-risk (score 2), and 55% for the high-risk (score ≥3; P < .0001) groups. In the validation cohort (N = 335), the model maintained its prognostic value, with a 5-year OS of 93%, 90%, 75%, and 57% for the four groups, respectively (P < .0001). Modified Staging System for WM (MSS-WM), utilizing age, albumin, and LDH is a simple, clinically useful, and externally validated prognostic model that reliably risk-stratifies patients with symptomatic WM into four groups with distinct prognosis.

Clinical Characteristics, Treatment Approach and Long-Term Outcomes of 678 Patients with Symptomatic Waldenstrom's Macroglobulinemia: Comprehensive Insights from a Spanish Registry of IgM Gammapathies

Introduction The pathogenesis of Waldenstrom's macroglobulinemia (WM) involves the clonal expansion of lymphoplasmacytic B cells in bone marrow, producing monoclonal immunoglobulin M (IgM). The heterogeneity of clinical manifestations in this uncommon disease represents the treatment approach more challenging. Multicenter registries may help in improving health care and scientific research. PRAME is a Spanish national registry of WM and IgM-related disorders with comprehensive data collection, providing insights for a better understanding of WM. Methods This is a retrospective, multicenter study that included newly diagnosed symptomatic WM (SWM) patients, evaluated at (24) Spanish hospitals between 1990 and 2023. All patients had confirmed diagnoses of SWM according to the International Workshop Consensus. Data collection on patients' demographics and disease epidemiology, clinical characteristics, diagnosis, treatment approaches and outcomes were performed from patients' local medical files. Results From 1796 total patients included in the Spanish registry for IgM gammopathies, a total of 678 newly SWM patients were identified. The median age was 71(range 35-94) years, 37% of patients had aged ≥ 75 years and 63% were male. The most common symptom at diagnosis was anemia (43%), followed by B symptoms (30%). Fifteen percent had peripheral neuropathy (PN) as the first WM symptom (39% with sensitive motor PN). Hyperviscosity was only observed in 15%. The free light chain isotypes were mostly kappa (75.4%). Less than 5% of the total cohort, had an ECOG ≥3, at diagnosis. Among 403 patients, who had samples available for assessing MYD88L265P by quantitative allele-specific PCR, 75% were positive for the mutation. However, out of the 199 patients assessed for CXCR4(S388X) mutation, only 12% were positive. The first line of therapy was started in 98% of patients. Plasmapheresis was indicated in 10%, with a median number of 2 sessions. The most frequent indications for initiating the treatment were anemia (48%), B symptoms (13%), and neuropathy (9%). Symptoms related to IgM monoclonal and extramedullary involvement were seen in 15% (56% associated with hyperviscosity) and 11.3%, respectively. The main first-line treatment regimens received were: chlorambucil (37%), dexamethasone, rituximab and cyclophosphamide (DRC)(21%), rituximab monotherapy (13%), bendamustine/rituximab (BR) (9.1%), Bruton tyrosine kinase (BTK) inhibitors (7%), and bortezomib, dexamethasone and rituximab (BDR) (5.5%). The overall and major response rates (ORR and MRR) were 67% and 58%, respectively. (Table 1). The MRR was higher among patients who received BR as the first line of therapy (88%), with a 26% of complete response (CR) and 21% of very good partial responses (VGPR). The CR+VGPR rates with other common regimens were 17% for DRC, 9% for BDR and 21% for BTK inhibitors, respectively. With a median follow-up of 96 months (IQR, 43 to 192), the median overall survival (OS) was 8.7 years (95% confidence interval [CI]:7.3-10.1) and the median progression-free survival (PFS) was 6.8 years (95% CI:6.2-7.5) with no relevant improvement over the last years. (Figure 1) Conclusion In the current registry, we observed a high proportion of younger patients with good performance status at diagnosis. Among newly diagnosed SWM patients, BR demonstrated ongoing superiority as a front line of therapy, leading to deeper responses compared to other therapeutic schemes. There were no significant differences in OS between different times of diagnosis. This Spanish registry for SWM contributes to advancing knowledge and the continual enhancement of treatment strategies for WM.

A Phase 4, Observational Study Evaluating the Efficacy and Safety of the Bruton Tyrosine Kinase Inhibitor (BTKi) Zanubrutinib in Patients with Waldenström Macroglobulinemia (WM)

Background and Significance:Zanubrutinib, a next-generation, selective BTKi, is approved for treatment of WM based on data from the phase 3 ASPEN study (NCT03053440), in which zanubrutinib showed a favorable benefit-risk profile vs ibrutinib, a first-generation BTKi, in patients with symptomatic WM (Tam CS, et al. Blood. 2020;136:2038-2050). In ASPEN, zanubrutinib showed consistent efficacy across patient subgroups, including prior treatment status (treatment naive or relapsed/refractory) and MYD88 mutational status (shown to affect prognosis and response to treatment). This registry study will contribute to a more inclusive evidence base for zanubrutinib treatment in populations underrepresented in previous clinical studies, specifically patients who are treatment naive, have non-L265 MYD88 mutations, orare from racial and ethnic minority groups. Study Design and Methods:This is a hybrid (retrospective and prospective), multicenter (US only), noninterventional registry study (NCT05640102) in adult patients (aged ≥18 years) with a histologically confirmed diagnosis of WM who are either receiving or planning to initiate zanubrutinib treatment (Figure). Patients with measurable disease (immunoglobulin M level &amp;gt;0.5 g/dL) at zanubrutinib initiation are eligible. Patients with disease transformation prior to zanubrutinib initiation, other non-Hodgkin lymphoma subtypes, or other malignancies (active or in the past ≤1 year) are excluded. Patients will be assigned to 1 of 2 cohorts based on MYD88 status determined using bone marrow specimens. Cohort 1 will include patients with MYD88L265P mutations who are treatment naive (arm A) or have relapsed/refractory disease (arm B). Arm A will enroll mostly patients from racial and ethnic minority groups (Black/African American, Asian, Indigenous/Native American, Native Hawaiian/Other Pacific Islander, and Hispanic/Latino), and arm B will only enroll patients from racial and ethnic minority groups. Cohort 2 will include patients with non-L265P MYD88 mutations or MYD88 wild type who are treatment naive or have relapsed/refractory disease in a single arm (arm C). The dose and duration of zanubrutinib treatment is at the discretion of the prescribing physician. Data collection will occur at screening, every 3 cycles during year 1 of zanubrutinib treatment, and every 6 cycles thereafter (28-day cycles). The primary endpoint is the major response rate (MRR) per investigator using Sixth International Workshop on Waldenström Macroglobulinemia response criteria (Owen RG, et al. Br J Haematol. 2013;160:171-176). Secondary endpoints are very good partial response or better (VGPR+) rate, overall response rate (ORR), duration of response (DOR), and treatment-emergent adverse events. Efficacy and safety analyses will be conducted descriptively for each study arm. MRR, VGPR+ rate, and ORR will be presented with 95% CIs, and median DOR will be estimated with the Kaplan-Meier method. The study is currently open for enrollment.

Development of a Novel Prognostic Score in Patients with Waldenström Macroglobulinemia Prospectively Enrolled in the Observational NF10 Study of Fondazione Italiana Linfomi

Background. IPSSWM and revised-IPSSWM are the two currently prognostic scores used for survival prediction in symptomatic Waldenström Macroglobulinemia (WM) patients in need of treatment. In addition to age and serum beta-2 microglobulin levels, which are present in both scores, the IPSSWM includes anemia, thrombocytopenia and the concentration of the serum monoclonal component (MC), while revised-IPSSWM includes LDH and serum albumin levels. Both IPSSWM and revised-IPSSWM have been developed in retrospective series and apply only to symptomatic WM patients. Aim. To analyze WM patients prospectively enrolled in the NF10 observational study since 2010 with the aim to define a prognostic score applicable to all WM patients at diagnosis, either symptomatic or asymptomatic. Methods. The progression-free survival (PFS) and overall survival (OS) rate was estimated and plotted using the Kaplan-Meier method, with 95% confidence interval (95% CI), and the effect of covariables on PFS was estimated by means of the Cox proportional hazard (PH) regression. The association with PFS was expressed as hazard ratio (HR) with 95% CI, either in univariable or multivariable regression. All statistical tests were two-sided. The proportionality of risk of the multivariable Cox PH model was checked graphically by means of the scaled Schoenfeld residuals, and the model performance was analyzed using the likelihood displacement method. Starting from a model with 10 variables selected on the basis of clinical and statistical considerations, the final model was selected on considering the Akaike (AIC) and likelihood ratio test. The cut-offs were selected after modelling the covariate with restricted cubic spline in Cox regression. The final model was internally validated using bootstrap techniques to evaluate the discriminant power (C-index), slope shrinkage to check for overfitting, and calibration (comparison between predicted and actual survival). Results. We identified 303 eligible patients from the NF10 study, of whom 185 (60%) needed treatment immediately after diagnosis (42%) or later (18%). These were main patients characteristics: 59% were male, 46% were aged &amp;gt;70 years, 8% had constitutional symptoms, 55% had Hb &amp;lt;12 g/dL, 54% had an absolute lymphocyte count ≥2x10 9/L, 9% had platelets &amp;lt;100x10 9/L, 37% had a serum MC &amp;gt;2 g/dL, 21% had albumin &amp;lt;3.5 g/dL, 23% had LDH &amp;gt; upper limit of normal (ULN), 32% had beta-2 microglobulin &amp;gt;1.5xULN. With a median follow-up of 51 months, 5-year PFS for the entire cohort was 67% (95%CI 60-73%). In univariate analysis, age &amp;gt;70 years (P=0.043), constitutional symptoms (P=0.009), nodal sites (P=0.002), Hb &amp;lt;12 g/dL (P&amp;lt;0.001), absolute lymphocyte count ≥2x10 9/L (P=0.033), serum MC &amp;gt;2 g/dL (P=0.003), high beta-2 microglobulin (P&amp;lt;0.001) and LDH (P=0.001), albumin &amp;lt;3.5 g/dL (P&amp;lt;0.001), C-reactive protein &amp;gt;4 mg/dL (P=0.008) were associated with shorter PFS. In multivariate analysis, age, anemia, hypoalbuminemia and high LDH retained prognostic value and thus entered the final model. Patients were classified into 3 risk groups: low (0-1 factors, 62% of patients), intermediate (2 factors, 24%) or high (3-4 factors, 15%), with a 5-year PFS of 80% (95%CI 70-87%), 49% (95%CI 32-64%) and 25% (95%CI 11-42%), respectively, with C-Harrell=0.744 and robust internal validation and calibration. OS was respectively 96% (95%CI 90-98%), 77% (95%CI 62-87%) and 43% (95%CI 25-60%) for the low, intermediate and high risk group (Figure 1). Conclusions. We developed a prognostic model based on 4 parameters easily attainable in clinical practice, able to predict PFS and OS at diagnosis. This is the first prognostic score for WM developed in a prospective study and applicable to patients presenting either with symptomatic or asymptomatic disease. This prognostic model identifies a subset of high-risk patients with a dismal outcome and a median OS &amp;lt;5 years. External validation in independent cohorts is needed.

Mutational Landscape of Bone Marrow CD19 and CD138 Cells in Waldenström Macroglobulinemia (WM) and IgM Monoclonal Gammopathy of Undetermined Significance (IgM MGUS)

Background Waldenström's Macroglobulinemia (WM) is an incurable B-cell neoplasm characterized by serum monoclonal immunoglobulin M (IgM) and clonal lymphoplasmacytic cells infiltrating the bone marrow (BM). Smoldering WM (sWM) is the asymptomatic/indolent form with a high risk of progressing to symptomatic WM requiring treatment whereas IgM monoclonal gammopathy of undetermined significance (IgM MGUS) is an early precursor stage of WM. Despite recurrent and activating mutations, including MYD88, CXCR4, ARID1A, KMT2D, and CD79B have been identified, the genetic basis for WM and the risk of progression of IgM MGUS to WM remain to be fully elucidated. Methods Based on the mutational profiling of WM and our previous wide transcriptome analyses on BM CD19+ and CD138+ cells of patients with WM and IgM MGUS, we decided to investigate the mutation status of these patients as follows: WM (n=10), sWM (n=7), and IgM MGUS (n=5), by performing high throughput targeted AmpliSeq next generation sequencing on 117 target genes potentially involved in B-cell lymphomagenesis and in the risk of progression of IgM MGUS to WM (Trojani A. et al. Cancers, 2021). Results We identified genetic aberrations in multiple genes, including previously described classic mutations in MYD88 (L260P alias L265P) found in 82.3% (14/17) of WM/sWM patients and in 60% (3/5) of IgM MGUS subjects. The CXCR4 mutation (S338Ter) was detected in 23.5% of CD19+ cells of WM patients, whereas it was absent in IgM MGUS subjects. Interestingly, we also identified new mutated genes, including WNK2 somatic mutations affecting 47% of WM patients, for which a recurrent allelic variant (V1635Ter) was observed, and BCL9 with a recurrent frameshift variant (P516Lfs) identified in 29.4% of WM patients exclusively in the CD19 cell fraction. The BCL9 (P516Lfs) variant was also detected in the B cells of one IgM MGUS patient. Moreover, sequencing evaluation revealed recurrently frameshift or missense mutations involving NFKB2 (L473Afs), PTPN13 (P1546Tfs), CARD11 (S622del), KMT2C (I823T), and ATM in WM and IgM MGUS patients (Figure 1). Of interest, KMT2C (also known as MLL3) exhibited a somatic hypermutated phenotype in both CD19+ and CD138+ cells of WM and IgM MGUS samples. The KMT2C mutations were not mutually exclusive with those involving KMT2D in our cohort of patients. Conclusion The present genomic analysis revealed new insights into the mutational landscape of Waldenström Macroglobulinemia, providing evidence of the recurrence of some variants in subjects with IgM MGUS as well. Notably, we uncovered new genetic mutations with somatic variants recurrently observed (n≥3) in KMT2C, WNK2, BCL9, PTPN13, CARD11 and NFKB2 genes. These recurring somatic events provide a genomic basis for future research and a better understanding of the WM pathogenesis as well as the risk of transformation of IgM MGUS to WM.

Clonal architecture and evolutionary history of Waldenström's macroglobulinemia at the single-cell level.

To provide insight into the subclonal architecture and co-dependency patterns of the alterations in Waldenström's macroglobulinemia (WM), we performed single-cell mutational and protein profiling of eight patients. A custom panel was designed to screen for mutations and copy number alterations at the single-cell level in samples taken from patients at diagnosis (n=5) or at disease progression (n=3). Results showed that in asymptomatic WM at diagnosis, MYD88L265P was the predominant clonal alteration; other events, if present, were secondary and subclonal to MYD88L265P. In symptomatic WM, clonal diversity was more evident, uncovering combinations of alterations that synergized to promote clonal expansion and dominance. At disease progression, a dominant clone was observed, sometimes accompanied by other less complex minor clones, which could be consistent with a clonal selection process. Clonal diversity was also reduced, probably due to the effect of treatment. Finally, we combined protein expression with mutational analysis to map somatic genotype with the immunophenotype. Our findings provide a comprehensive view of the clonality of tumor populations in WM and how clonal complexity can evolve and impact disease progression.

Waldenström's macroglobulinemia - clinical symptoms and review of therapy yesterday, today and tomorrow.

Waldenström macroglobulinemia (WM) is a lymphoplasmocytic lymphoma with immunoglobulin M monoclonal protein. The incidence of this disease is very low (0.4/100,000), so that this disease can be regarded as an orphan's disease. It means that new drugs are often tested and registered for more frequent diseases. In this review we will focus on the efficacy of the new drugs for WM. The current treatment options for symptomatic WM patients include alkylating agent cyclophosphamide and anti-CD20 monoclonal antibodies. Therapy with rituximab and bendamustin resulted in longer therapeutic response then therapy with rituximab, cyclophosphamide and dexamethasone. Many drugs, used in multiple myeloma (MM), shoved promising results in WM patients. Bortezomib is effective in WM, but its neurotoxicity is higher in WM than in MM patients. Therefore, new proteasome inhibitors, carfilzomib and ixazomib, are better tolerated as documented in several studies. New types of antiCD20 antibody (obinutuzumab) can be used in patients with rituximab intolerance. in five of our patients with WM, obinutuzumab and bendamustin reached deeper responses than therapies administered in previous lines of therapy. Oral Bruton tyrosine kinase (BTK) inhibitor ibrutinib alone and in combination with rituximab have extended the treatment options for WM patients. New BTK inhibitors (e. g. acalabrutinib, zanubrutinib, and vecabrutinib) were tested and their lower toxicity (atrial fibrillation) was documented. Moreover, the BCL2 inhibitor venetoclax is newly tested. New antiCD20 antibody (obinutuzumab) is of advantage in patients with WM with rituximab intolerance as well as bendamustin and new proteasome inhibitors (ixazomib and carfilzomib) or new BTK inhibitors with lower cardiotoxicity. Many of the abovementioned drugs do not have official registration for WM and can be administrated with the consent of the health care provider only. Thus, this work brings evidence of their efficacy.

Waldenström macroglobulinemia whole genome reveals prolonged germinal center activity and late copy number aberrations.

The genomic landscape of Waldenström macroglobulinemia (WM) is characterized by somatic mutations in MYD88, present from the precursor stages. Using the comprehensive resolution of whole genome sequencing (WGS) in 14 CD19-selected primary WM samples; comparing clonal and subclonal mutations revealed that germinal center (GC) mutational signatures SBS9 (poly-eta) and SBS84 (AID) have sustained activity, suggesting that the interaction between WM and the GC continues over time. Expanding our cohort size with 33 targeted sequencing samples, we interrogated the WM copy number aberration (CNA) landscape and chronology. Of interest, CNA prevalence progressively increased in symptomatic WM and relapsed disease when compared with stable precursor stages, with stable precursors lacking genomic complexity. Two MYD88 wild-type WGS contained a clonal gain affecting chromosome 12, which is typically an early event in chronic lymphocytic leukemia. Molecular time analysis demonstrated that both chromosomal 12 gain events occurred early in cancer development whereas other CNA changes tend to occur later in the disease course and are often subclonal. In summary, WGS analysis in WM allows the demonstration of sustained GC activity over time and allows the reconstruction of the temporal evolution of specific genomic features. In addition, our data suggest that, although MYD88-mutations are central to WM clone establishment and can be observed in precursor disease, CNA may contribute to later phases, and may be used as a biomarker for progression risk from precursor conditions to symptomatic disease.

Report of consensus panel 5 from the 11th international workshop on Waldenstrom's macroglobulinemia on COVID-19 prophylaxis and management

Consensus Panel 5 (CP5) of the 11th International Workshop on Waldenstrom's Macroglobulinemia (IWWM-11; held in October 2022) was tasked with reviewing the current data on the coronavirus disease-2019 (COVID-19) prophylaxis and management in patients with Waldenstrom's Macroglobulinemia (WM). The key recommendations from IWWM-11 CP5 included the following: Booster vaccines for SARS-CoV-2 should be recommended to all patients with WM. Variant-specific booster vaccines, such as the bivalent vaccine for the ancestral Wuhan strain and the Omicron BA.4.5 strain, are important as novel mutants emerge and become dominant in the community. A temporary interruption in Bruton's Tyrosine Kinase-inhibitor (BTKi) or chemoimmunotherapy before vaccination might be considered. Patients under treatment with rituximab or BTK-inhibitors have lower antibody responses against SARS-CoV-2; thus, they should continue to follow preventive measures, including mask wearing and avoiding crowded places. Patients with WM are candidates for preexposure prophylaxis, if available and relevant to the dominant SARS-CoV-2 strains in a specific area. Oral antivirals should be offered to all symptomatic WM patients with mild to moderate COVID-19 regardless of vaccination, disease status or treatment, as soon as possible after the positive test and within 5 days of COVID-19-related symptom onset. Coadministration of ibrutinib or venetoclax with ritonavir should be avoided. In these patients, remdesivir offers an effective alternative. Patients with asymptomatic or oligosymptomatic COVID-19 should not interrupt treatment with a BTK inhibitor. Infection prophylaxis is essential in patients with WM and include general preventive measures, prophylaxis with antivirals and vaccination against common pathogens including SARS-CoV-2, influenza, and S. pneumoniae.

Prevalence of Monoclonal Gammopathy of Clinical Significance (MGCS) Among Patients with Monoclonal Gammopathies: Report from a Referral Center

Monoclonal gammopathies (MG) may be associated with a variety of syndromes due to the properties of the monoclonal protein, ectopic production of cytokines or other mechanisms. These syndromes may involve the kidneys, peripheral nerve, skin, eyes or other non-organ confined systemic syndromes. These disorders are usually associated with a nonmalignant or premalignant B-cell or plasma cell clone that does not fulfill the typical criteria of symptomatic myeloma or Waldenström's macroglobulinemia. These heterogeneous syndromes have attracted increasing attention and have been termed as "Monoclonal Gammopathy of Clinical Significance" (MGCS), however, their diagnosis remains challenging, requiring a high degree of suspicion or invasive target organ biopsies. Because of the difficulties in their recognition, it is not known how common these syndromes are among patients with monoclonal gammopathies. On the other hand, MG is a frequent finding: a recent prospective study in Iceland reported a prevalence of ~5% among subjects over the age of 40. Thus, the prevalence of MGCS may be significantly underestimated due to the heterogeneous phenotype, the difficulties in establishing the diagnosis and low degree of suspicion. In order to provide an estimate of the prevalence of MGCS among patients with known MG, we analyzed the database of a plasma cell dyscrasia referral center, in Athens, Greece. This is a prospectively maintained database which includes all patients with monoclonal gammopathies who are referred to our center for evaluation or treatment. Since AL amyloidosis is associated with a more aggressive clinical phenotype and requires prompt initiation of therapy, we evaluated these patients separately in our analysis. Because of an increasing interest in MGCS after 2010, and subsequent rising awareness and diagnostic sensitivity, we excluded earlier referrals and focused only on patients who were referred after 1/1/2010. The analysis included all patients who were referred for evaluation because of MG with or without concomitant symptoms or laboratory abnormalities. From 1/1/2010 to 31/12/2021, 3138 patients were referred for evaluation. The final diagnosis was MGUS or asymptomatic myeloma or asymptomatic WM in 1437 patients, symptomatic MM in 1145 patients, AL amyloidosis in 320 patients, symptomatic WM in 108 patients and a MGCS-related syndrome was diagnosed in 128 patients (4.1%). Among those with MGCS, the majority had either MGRS (n=51) or IgM-related neuropathy (n=58); other specific diagnoses included POEMS syndrome, Schnitzler's syndrome, necrobiotic xanthogranuloma or scleromyxedema, and other rare syndromes (TEMPI syndrome, IgM retinopathy, Clarkson's syndrome). Peripheral neuropathy with a concomitant MG was the most common co-existing condition among non-AL amyloidosis patients: 73% had IgM and 37% a non-IgM MG. A causal relationship between MG and neuropathy was established for 42% of those with non-IgM neuropathy (mainly due to POEMS syndrome). The median age of the MGCS patients was 64, not significantly different in clinical terms from that of patients with SMM/MGUS, AL amyloidosis, symptomatic MM and symptomatic WM (which was 65, 65, 67 and 70 years respectively). The baseline level of monoclonal immunoglobulin among MGCS patients was low (median 0.4 gr/dl) and significantly lower than in patients with MGUS/SMM/aWM (median 1.04 gr/dl). The median BM infiltration by clonal cells in patients with MGCS was 10%, and was 7% in the MGUS/SMM group, 15% in patients with AL amyloidosis, 50% in patients with symptomatic MM and 40% for patients with symptomatic WM. Most patients with MGCS received anticlonal therapy; other non-clone targeting therapies were used in patients with Schnitzler's syndrome and Clarkson's disease. A significant proportion of patients with IgM-related neuropathy received only supportive therapy. In conclusion, MGCS was found in ~4% of patients with MG in a plasma cell dyscrasia referral center. The establishment of MGCS diagnosis requires high degree of clinical suspicion due to their rarity and highly heterogeneous clinical presentation. Despite the bias associated with the analysis from a referral center, given the frequency of MG in the general population, there is probably a significant number of patients with MGCS who remain underdiagnosed and may suffer from complications associated with an otherwise non-malignant plasma cell dyscrasia.

Progression Risk and Long-Term Survival Trends of 915 Patients with Asymptomatic IgM Monoclonal Gammopathy

BACKGROUND: Waldenström macroglobulinemia (WM) is a lymphoplasmacytic lymphoma with a serum monoclonal IgM. Early asymptomatic stages include IgM monoclonal gammopathy of undetermined significance (MGUS) and smoldering WM (SWM). While most IgM MGUS patients (pts) will not progress during follow-up, a greater proportion of SWM pts will do. Most prognostic models identify high-risk SWM; however, they fail to characterize IgM MGUS and low-risk SWM. Moreover, data is scarce regarding how IgM MGUS and SWM survival trends have evolved during the last decades. We wondered whether inclusion of new biomarkers could improve progression risk models using the largest cohort of IgM MGUS and SWM reported. Here, we describe a comprehensive proposal to model progression risk and give more insight into the survival trends of IgM MGUS and SWM using retrospective data from 13 Spanish hospitals. METHODS: Diagnostic criteria were defined by the Second International Workshop. MYD88 L265P was analyzed by allele-specific or digital droplet polymerase chain reaction. Progression free survival (PFS) was calculated from the date of diagnosis to last follow-up or disease progression (symptomatic WM, other non-Hodgkin lymphoma or AL amyloidosis). Overall survival (OS) was calculated up to death from any cause. To find the best model, we first used a backward stepwise regression with meaningful variables as continuous. Also, a logistic and lasso regression (least shrinkage and selection operator) selected important variables that predicted progression at 10 years. We then categorized continuous data according to Liu and Youden methods. Relative survival (RS) was calculated using the Ederer II method leveraging the Human Mortality Database. RESULTS: 915 pts (462 IgM MGUS and 453 SWM) were included. Median age at diagnosis was 70 years. 102 (11%) pts were diagnosed before the year 2000. MYD88 L265P (available in 465 pts) was detected in 107 (54%) IgM MGUS and 217 (81%) SWM pts. After a median follow-up of 6 years, disease progression was documented in 250 pts (16% in IgM MGUS and 39% in SWM). The incidence rate of progression per 100 person-years was 2.9 (95% confidence interval [CI] 2.4 - 3.7) and 7.0 (95% CI 6.1 - 8.2) in IgM MGUS and SWM, respectively. Continuous (serum IgM, IgG, IgA, albumin, β2-microglobulin, bone marrow infiltration [BM]) and categorical (MYD88 L265P) candidates to clinical significance were fitted into a backward stepwise regression. Low IgG (hazard ratio [HR] 0.92; p=0.03), high IgM (HR 1.03; p<0.01), high BM infiltration (HR 1.02; p=0.01), and low albumin (HR 0.37; p<0.01) were selected. As the median follow-up of our series was 6 years, we also performed lasso to select predictors of progression at 10 years. Here, all previous variables were selected plus low IgA. We then chose the 4 best predictors between the two methods (BM infiltration, IgM, decreased IgG/IgA, and albumin). To fit into an easy-to-use model, we categorized continuous data as meaningful for clinicians. Albumin (<3.5 g/L) and IgG/IgA (<6.8/0.6 g/L) were categorized below the normal values; BM infiltration (≥ 20%) and IgM (≥ 10 g/L) cutpoints were established as previously described. 553 pts were introduced in the final model. Each variable was assigned a point so that low (0-1), intermediate (2) and high-risk (3-4) groups were able to discriminate pts. 84% of IgM MGUS pts were categorized as low-risk, while 57% of SWM were intermediate or high-risk. Regarding OS, there were no differences between IgM MGUS and SWM; however, each stage clearly differed from that of series of symptomatic WM pts from the same hospitals (p<0.01) (Figure 1A). Regarding survival trends, IgM MGUS had a RS slightly higher than that of the matched general population during the first 10 years of diagnosis, with a subsequent decline especially at 20 years. SWM had a RS lower than the general population, with a difference observed from the first 10-15 years of diagnosis (Figure 1B). CONCLUSION: We developed a new single ready-to-use risk model accounting for both IgM MGUS and SWM. Most IgM MGUS pts were categorized in the low-risk group, while SWM accounted for the vast majority of intermediate and high-risk groups. There were no differences in OS between IgM MGUS and SWM. However, RS of IgM MGUS was higher in the first 10 years from diagnosis, probably due to both early access to public health and follow-up, while SWM showed a constant decreasing RS. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Prognostic Role of Revised International Prognostic Score for Waldenstrom Macroglobulinemia (rIPSSWM) in Newly Diagnosed Waldenstrom Macroglobulinemia/Lymphoplasmacytic Lymphoma: A Report from the NF10 International, Prospective, Observational Study of the Fondazione Italiana Linfomi

Background: Revised international prognostic score for Waldenstrom macroglobulinemia (rIPSSWM) has been recently validated for symptomatic WM patients in need of treatment and was built on the independent prognostic role of Age, LDH, Serum Albumin and Beta2microglobulin. In 2010 the NF10 study was started by the Fondazione Italiana Linfomi as a prospective registry specifically devised for investigating the prognosis of, Indolent non follicular B-Cell Lymphomas (INFL) including small lymphocytic lymphoma (SLL), lymphoplasmacytic lymphoma/Waldenstrom macroglobulinemia (LPL/WM) and marginal zone lymphomas (MZL). Methods: We aimed to assess the prognostic role of RIPSSWM (ref) on an unselected population of treatment naïve patients with LPL/WM enrolled in the NF10 registry. Main study endpoint was Overall Survival. Secondary endpoint was treatment free survival (TFS). Results: From July 2010 to January 2020, 1535 INFL cases were registered and 1328 validated. Three hundred and seventeen cases were LPL/WM. Median age was 69 years (range 60-76); 6% had ECOG performance status > 1, median hemoglobin concentration was 12 g/dl (IQR 10 - 13.6), median serum albumin was 4 g/dl (IQR 3.6 - 4.3); serum CM was present in 254 patients with median concentration of 1.6 g/dl (IQR 0.74 - 2.4). Lactate dehydrogenase and b2-microglobulin were elevated in 21% and 59% of cases, respectively. Overall, 191 patient received systemic therapy. Immediate systemic therapy was planned in 133 (42%) patients. Additionally 58 patients required systemic treatment due to progressive disease from watch and wait. Median time to treatment for WW patients was 18 months (95% CI 15 to 28). When systemic therapy was prescribed rituximab (R) was used in 82% and was combined with cytotoxic therapy in 76% of cases. Regarding immunochemotherapy regimens, R was combined with bendamustine in 34%, alkylating agents in 30%, fludarabine in 8%, and CHOP like in 4%. With 58 months of median follow up (1 - 114), 5-year overall survival (OS) was 83% (95%CI: 78-88). In univariate analysis of OS, Age (>75years), elevated LDH, elevated B2M, and low serum albumin (<3.5) were associated with a different risk of death; the initial choice of deferring therapy did not impact on OS. Revised IPSSWM score could be calculated for 228 patients: 34(15%), 55(24%), 63(28%), 60(26%), and 16(7%) patients had 0,1,2,3, or 4-5 risk factors, respectively. Five-year OS was 100%, 98%, 79%, 83%, and 29% by risk group (p<0.001; c-Harrel 0.792: Figure1). The risk of dying due to lymphoma progression or due to other causes was similarly low for low risk patients (0-1 risk factors). Intermediate (2-3 RF) and high risk patients (4-5 RF) had a three-fold higher risk of dying due to causes unrelated to lymphoma compared to lymphoma related deaths. rIPSSWM was also correlated with a different TFS among patients initially observed (Figure 1: median TFS not reached for 0 RF, vs 15 months for 1-3 RF, vs 1.5 months for 4-5 RF p <0.001). Conclusions: We were able to validate the prognostic role of rIPSSWM in an unselected population of newly diagnosed patients with LPL/WM thus extending the usefulness of this score to asymptomatic patients. The rIPSSWM was particularly able to identify a small group of patients at very high risk of death within few months from the diagnosis. Moreover the rIPSSWM was also able to predict the time to initial treatment for patients who were initially observed. The NF10 study confirms that a web-based world-wide cooperation allows the collection of a relevant and complete data set, providing a platform for future prognostic and pathobiological studies. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Prognostic Impact of MYD88 L265P Mutation By Droplet Digital PCR in IgM MGUS and Smoldering Waldenström Macroglobulinemia

BACKGROUND: MYD88 L265P mutation is highly prevalent in IgM monoclonal gammopathy of undetermined significance (MGUS), smoldering Waldenström macroglobulinemia (SWM) and symptomatic WM. Allele-specific PCR (AS-PCR) has been used routinely to assess MYD88 mutation; however, with the advent of more precise high-throughput technologies such as droplet digital PCR (ddPCR), absolute quantification can be achieved. There is no data regarding ddPCR applicability in asymptomatic IgM monoclonal gammopathies or as a prognostic biomarker. Here, we aimed to compare MYD88 quantification by ddPCR with clinical and laboratory features and to analyze the prognostic impact in a series of patients (pts) with IgM MGUS and SWM.METHODS: We analyzed bone marrow (BM) and peripheral blood (PB) samples stored from pts diagnosed with IgM MGUS and SWM at our institution from 1980 to 2020. DNA extraction methods followed manufacturer instructions (Qiagen) to obtain genomic DNA from unsorted BM samples and cell-free DNA (cfDNA) from PB. MYD88 L265P mutation was quantified by ddPCR using a Bio-Rad commercial assay (HEX-labeled wild-type allele; FAM-labeled mutant allele). We used OCI-Ly3 DLBCL ABC cell line, homozygous for MYD88 L265P, as a positive control. ddPCR was performed following Bio-Rad technical specifications using the QX200 droplet reader. Data was analyzed using QuantaSoft v.1.0 software (Bio-Rad). Absolute quantification of the mutation was expressed as percentage of fractional abundance. For survival analysis, we used a competing risk analysis to evaluate the prognostic impact of MYD88 mutation on progression to symptomatic WM.RESULTS: A total of 217 unsorted samples were analyzed (187 BM and 30 PB). Genomic DNA from unsorted BM samples was extracted from pts diagnosed with IgM MGUS (46%), SWM (44%), and symptomatic WM (10%). cfDNA was obtained from a subgroup of pts with IgM MGUS (52%) and SWM (48%). Median age at diagnosis was 68 (range 61 to 76). AS-PCR could detect the mutation in 22 (31%) pts with IgM MGUS and 49 (75%) with SWM. ddPCR improved precision detection up to 48 (55%) pts with IgM MGUS and 68 (83%) with SWM. All pts with symptomatic WM harbored the MYD88 mutation, as identified by both techniques. Median absolute quantification from BM was 2.3% and 7% for pts with IgM MGUS and SWM, respectively (p<0.001).Pearson correlation coefficients comparing BM MYD88 mutation quantification by ddPCR with serum M-protein size, IgM concentration, BM lymphoplasmacytic infiltration rate and BM CD19+ cells were 0.3, 0.4, 0.6, and 0.9 (p<0.0004), respectively. Similar coefficients were observed in symptomatic WM regarding BM infiltration rate (0.6; p=0.001) and BM CD19+ cells (0.9; p<0.0001). Spearman correlation coefficients comparing cfDNA MYD88 mutation quantification with BM lymphoplasmacytic infiltration rate and BM CD19+ cells were 0.4 and 0.5 (p<0.008), respectively. Agreement regarding MYD88 mutation detection by ddPCR in BM DNA and cfDNA samples was 82% (Cohen kappa index 0.6).With a median overall survival of 13 years in pts with IgM MGUS and SWM, 13% of them progressed to symptomatic WM while 22% died without progression. Cox univariate analysis using continuous values for MYD88 quantification (p=0.004), serum IgM (p<0.001), BM lymphoplasmacytic infiltration (p<0.001), and serum albumin (p=0.04) were significant. X-tile software was used to find the optimal cutoff point of MYD88 quantification as a biomarker. 4.5% was established for pts with IgM MGUS while 25% for SWM. Using the Fine and Gray regression model in a competing risk analysis taking death without progression as a competing event, higher MYD88 mutation burden negatively impacted the risk of progression of IgM MGUS (SHR 4.6; p=0.003) and SWM (SHR 6; p<0.001) (Figure 1).CONCLUSION: Quantification of the MYD88 L265P mutation by ddPCR has higher precision and sensitivity compared to AS-PCR; thus ddPCR could be used as a potential new and useful biomarker. MYD88 tumor burden correlated with well-known laboratory parameters used for diagnosis and risk stratification, whether using genomic DNA from unsorted BM samples or cfDNA. Risk of progression was higher in patients harboring an increased mutant allele burden. This is the first report showing the prognostic impact of MYD88 quantification in a series of patients with asymptomatic IgM gammopathy and long-term follow up. [Display omitted] DisclosuresCibeira: Akcea: Honoraria, Membership on an entity's Board of Directors or advisory committees; Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees; Celgene: Honoraria; Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees. Bladé Creixenti: Janssen, Celgene, Takeda, Amgen and Oncopeptides: Honoraria. Rosinol: Janssen, Celgene, Amgen and Takeda: Honoraria. Fernandez de Larrea: BMS: Consultancy, Honoraria, Research Funding; Amgen: Consultancy, Honoraria, Research Funding; Takeda: Honoraria, Research Funding; GSK: Honoraria; Sanofi: Consultancy; Janssen: Consultancy, Honoraria, Research Funding.

Clonal Hematopoiesis Is Associated with Increased Risk of Progression of Asymptomatic Waldenström Macroglobulinemia

▪IntroductionClonal hematopoiesis (CH) is associated with adverse outcomes in patients with non-Hodgkin lymphoma (NHL) and multiple myeloma undergoing autologous stem cell transplantation. Still, its implications for patients with indolent NHL have not been well studied. Here, we report the prevalence of CH in patients with Waldenström Macroglobulinemia (WM) and its association with clinical outcomes.MethodsWe retrospectively reviewed clinical data of 602 patients with IgM monoclonal gammopathy of undetermined significance (MGUS), smoldering WM (SWM), and WM who had clinical next-generation sequencing (NGS) performed on bone marrow aspirates or peripheral blood obtained between October 2014 and February 2020 at the Dana-Farber Cancer Institute. An Illumina Truseq amplicon-based NGS assay of 95 genes recurrently mutated in myeloid and lymphoid neoplasms was utilized. Each specimen yielded ~2 million reads and ~1500X average coverage, with 90% of amplicons having >200X coverage. Pathogenic driver variants were identified based on mutation type, position, and frequency in published reports and public databases. To unambiguously differentiate CH mutations from those in the WM clone, CH was defined by the presence of somatic mutations in DNMT3A, TET2, or ASXL1 (DTA).ResultsThe cohort included 147 patients with MGUS or asymptomatic WM and 453 patients with symptomatic WM, with a median age of 66 years (range = 40-89) and 68 years (range = 33-93), respectively, at the time of first NGS assay. The prevalence of CH-DTA was 14% in symptomatic WM patients and did not differ significantly in MGUS (13%) or SWM (14%). Among precursor patients, there was an increased risk of progression to symptomatic WM for those with CH-DTA [7/20 patients with vs. 11/116 without CH-DTA progressed over a median of 54 months (P = 0.002)]. In symptomatic WM patients, CH-DTA was positively associated with older age (P < 0.001) at the time of NGS, with a median age of 72 vs. 67 years for patients with versus those without CH-DTA. CH-DTA was not associated with inferior overall survival (OS) with a relatively short median follow-up from diagnosis and NGS assay. OS was 6.7 years (95% CI = 6.1-7.6) for patients with CH-DTA and 2.5 years for patients without DH-DTA (95% CI = 2.2-2.8). The most common cause of death was disease progression, with no significant difference between those with or without CH-DTA. Patients with CH-DTA had an increased risk of cardiovascular disease (30% vs. 18%, P = 0.036).ConclusionsWe demonstrate that CH is common in WM patients and is associated with an increased risk of progression from precursor states but not with inferior survival. Further work is needed to determine how the presence of CH might promote progression to WM and whether it can be incorporated into future risk stratification models. Importantly, our data do not support changes in clinical management or alterations in therapy for patients with WM and coexistent CH and reinforce the need to interpret NGS results within their specific clinical context. DisclosuresSteensma: Novartis: Current Employment. Castillo: Abbvie: Consultancy, Research Funding; BeiGene: Consultancy, Research Funding; Pharmacyclics: Consultancy, Research Funding; Janssen: Consultancy; Roche: Consultancy; TG Therapeutics: Research Funding. Treon: X4: Research Funding; Dana Farber Cancer Institute: Current Employment; Janssen: Consultancy, Research Funding; Pharmacyclics: Consultancy, Research Funding; BeiGene: Consultancy, Research Funding; Self: Patents & Royalties: Holder of multiple patents related to testing and treatment of MYD88 and CXCR4 mutated B-cell malignancies; BMS: Consultancy, Research Funding; AbbVie: Consultancy, Research Funding. Ghobrial: AbbVie, Adaptive, Aptitude Health, BMS, Cellectar, Curio Science, Genetch, Janssen, Janssen Central American and Caribbean, Karyopharm, Medscape, Oncopeptides, Sanofi, Takeda, The Binding Site, GNS, GSK: Consultancy. Sperling: Adaptive: Consultancy.

The Genomic Landscape of Waldenström Macroglobulinemia Reveals Sustained Germinal Center Activity and Late-Developing Copy Number Aberrations

The Genomic Landscape of Waldenström Macroglobulinemia Reveals Sustained Germinal Center Activity and Late-Developing Copy Number Aberrations

OAB-040: Clonal hematopoiesis is associated with increased risk of progression of asymptomatic Waldenström Macroglobulinemia

<h3>Background</h3> Clonal hematopoiesis (CH) is associated with adverse outcomes in patients with non-Hodgkin lymphoma (NHL) and multiple myeloma undergoing autologous stem cell transplantation. Still, its implications for patients with indolent NHL have not been well studied. Here, we report the prevalence of CH in patients with Waldenström Macroglobulinemia (WM) and its association with clinical outcomes. <h3>Methods</h3> We retrospectively reviewed clinical data of 602 patients with IgM MGUS, smoldering WM and WM who had clinical next-generation sequencing (NGS) performed on bone marrow aspirates or peripheral blood obtained between October 2014 and February 2020 at the Dana-Farber Cancer Institute (DFCI). An Illumina Truseq amplicon-based NGS assay of 95 genes recurrently mutated in myeloid and lymphoid neoplasms was utilized. Each specimen yielded ~2 million reads and ~1500X average coverage with 90% of amplicons having >200X coverage. Pathogenic driver variants were identified based on mutation type, position, and frequency in published reports and public databases. In order to unambiguously differentiate CH mutations from those in the WM clone, CH was defined by the presence of somatic mutations in DNMT3A, TET2 or ASXL1 (CH-DTA). <h3>Results</h3> The cohort included 147 patients with MGUS or asymptomatic WM and 453 patients with symptomatic WM with a median age of 66 years (range: 40-89) and 68 years (range: 33-93), respectively, at time of first NGS assay. The prevalence of CH-DTA was 14% in symptomatic WM patients and did not differ significantly in MGUS and SWM (13% and 14%, respectively). Among precursor patients, there was an increased risk of progression to symptomatic WM in those with CH-DTA (7/20 patients with vs. 11/116 without CH-DTA progressed over a median of 54 months [p= 0.002]). In symptomatic WM patients CH-DTA was positively associated with older age (p<0.001) at time of NGS, with a median age of 72 vs. 67 years for patients with versus those without CH-DTA. CH-DTA was not associated with inferior OS with a relatively short median follow-up from diagnosis and NGS assay of 6.7 (95% CI: 6.1-7.6) and 2.5 (95% CI: 2.2-2.8) years, respectively. The most common cause of death was disease progression with no significant difference between those with or without CH-DTA. Patients with CH-DTA had an increased risk of cardiovascular disease (30% vs. 18%, p=0.036). <h3>Conclusion</h3> We demonstrate that CH is common in WM patients and is associated with increased risk of progression from precursor states but not with inferior survival. Further work is needed to determine how the presence of CH might promote progression to WM and whether it can be incorporated into future risk stratification models. Importantly, our data do not support changes in clinical management or alterations in therapy for patients with WM and coexistent CH and reinforce the need to interpret NGS results within their specific clinical context.

Ibrutinib Is Highly Active As First Line Therapy in Symptomatic Waldenstrom's Macroglobulinemia

Activating mutations in MYD88 and CXCR4 mutations are present in 95-97% and 40-45% of previously untreated patients with Waldenström's macroglobulinemia, respectively. MYD88 mutations trigger malignant cell growth through Bruton's Tyrosine Kinase and Hematopoietic Cell Kinase, both targets of ibrutinib (Yang et al, Blood 2013; Blood 2016). CXCR4 mutations confer in vitro as well as clinical evidence of resistance in previously treated WM patients to ibrutinib (Cao et al, Leukemia 2014, Treon et al NEJM 2015). Ibrutinib produces overall and major [partial response (PR) or better] responses in 90% and 70-75% of previously treated WM patients (Treon et al, NEJM 2015; Dimopoulos et al, Lancet Oncol. 2017). The activity of ibrutinib in untreated, symptomatic WM patients is not known. We therefore investigated the activity and safety of ibrutinib in this patient population. Thirty patients were enrolled in this study. Key baseline characteristics were as follows: median age 67 (range 43-83 yrs); 23 (77%) were male, IPSSWM scores were low (n=5; 17%), intermediate (n=11; 37%), and high (n=14; 47%); median serum IgM was 4,369 (range 844-10,321); median hemoglobin level was 10.3 (range 7.5-14.5 g/dL); median serum B2M level was 3.8 (2.0-7.6 mg/L); adenopathy >1.5 cm (n=10; 33%); splenomegaly >15 cm (n=5; 17%), and median bone marrow disease involvement was 65% (range 5-95%). All patients expressed the MYD88L265P mutation, and 14 (47%) had a CXCR4 mutation. Patients received 420 mg a day of ibrutinib, and dose de-escalation for toxicity was permitted. The median time on therapy was 8.1 (range 2.0-16.4 months), and was similar for CXCR4 wild-type (CXCR4WT) and CXCR4 mutated (CXCR4Mut) patients (9.4 vs. 8.0 months, respectively p=0.98). The overall and major (>PR) response rates were 96.7% and 80%. Five (17%) patients achieved a VGPR. No complete responses were observed. At best response, median serum IgM level declined from 4,380 to 1,786 (p=0.0001). At baseline 18/30 (60%) patients had a serum IgM >3,000 mg/dL versus 2/30 (7%) patients at best response (p<0.0001). At best response, median bone marrow involvement declined from 65% to 20% (p<0.0001), with decreased or resolved adenopathy (n=7; 70%) and splenomegaly (n=4; 80%) observed in most patients with baseline extramedullary disease. The median hemoglobin level increased from 10.3 to 13.6 g/dL (p<0.0001). The impact of CXCR4 mutation status on responses and time to at least a minor (overall) and PR or better (major) response are shown in Table 1.With a median follow-up of 8.1 months, two patients met progression criteria while on therapy, both of whom were CXCR4 mutated, and one of whom self-held protocol therapy >2 weeks due to travel. The latter patient continues treatment for clinical benefit per protocol. Overall, treatment was well tolerated. Grade 2 AEs: arthralgia (n=1); bruising (n=1); procedure related bleeding (n=1); hypertension (n=2); muscle cramps (n=1); neutropenia (n=3); vasculitic rash (n=1); URI (n=1); UTI (n=2). Grade 3 AEs: reversible AST/ALT elevation (n=1); foot pain (n=1); thrombocytopenia (n=1); and hypertension (n=1). Three patients (10%) had treatment-related atrial arrhythmia [Grade 1 (n=1); Grade 2 (n=2)] and continued ibrutinib with medical management for their atrial arrhythmia. Four study patients are off protocol therapy due to progression (n=1); reversible drug-induced hepatitis (n=1); unrelated ventricular arrhythmia (n=1); and withdrawal of consent due to travel (n=1). One patient required dose reduction for vasculitic rash/foot pain (to 140 mg/day). Our findings provide the first report of activity and safety of ibrutinib in previously untreated and symptomatic patients with Waldenström's macroglobulinemia, and show that ibrutinib is highly active and well-tolerated as a single agent, with no unexpected toxicities. Delays in ibrutinib response are associated with expression of mutated CXCR4. (ClinicalTrials.gov number, NCT02604511). [Display omitted] DisclosuresTreon:Pharmacyclics: Consultancy, Research Funding. Castillo:Millennium: Research Funding; Abbvie: Research Funding; Pharmacyclics: Consultancy, Research Funding; Janssen: Consultancy, Research Funding.

Long-Term Follow-up of Previously Treated Patients Who Received Ibrutinib for Symptomatic Waldenstrom's Macroglobulinemia: Update of Pivotal Clinical Trial

MYD88 mutations are present in 95% of WM patients and trigger malignant cell growth through Bruton's Tyrosine Kinase and Hematopoietic Cell Kinase, both targets of ibrutinib. CXCR4 mutations are found in 30-40% of previously treated WM patients and confer in vitro resistance to ibrutinib. We therefore performed a prospective study that examined the activity of ibrutinib in previously treated WM patients (Treon et al, NEJM 2015). The findings showed that ibrutinib was highly active in previously treated WM patients and supported the first ever FDA and EMA drug approval for the treatment of WM. Herein, we provide a long-term follow-up of this study. Sixty-three symptomatic WM patients who received at least one prior therapy were enrolled. Their baseline characteristics were as follows: median age 63 (range 44-86 yrs); 48 (76%) were male, IPSSWM scores were low (n=14; 22%), intermediate (n=27; 43%), and high (n=22; 35%); median serum IgM was 3,520 (range 724-8,390 mg/dL); median hemoglobin level was 10.5 (range 8.2-13.8 g/dL); median serum B2M level was 3.9 (1.3-14.2 mg/L); adenopathy >1.5 cm (n=37; 59%); splenomegaly >15 cm (n=7; 11%), and median bone marrow disease involvement was 60% (range 3-95%). The median prior therapies was 2 (range 1-9), and 25 (40%) patients were refractory to their previous therapy. MYD88 and CXCR4 genotyping was performed for 63 and 62 patients, respectively and is shown in Table 1. Patients were initiated on 420 mg a day of ibrutinib, and dose de-escalation for toxicity was permitted. Patients received protocol administered ibrutinib for 40 months, and transitioned to commercial supply thereafter. Patients could consent to continue follow-up for response assessment after 40 months on commercial drug supply. Ibrutinib was administered until progression or intolerance. The median time on ibrutinib was 46.6 (range 0.5-60 months). Improvements in categorical responses occurred with prolonged treatment. The overall and major (>PR) response rates were 90.4% and 77.7%, respectively, and were not impacted by prior lines of therapy or relapsed or refractory status. Seventeen (27%) patients achieved a VGPR. No complete responses were observed. At best response, median serum IgM level declined from 3,520 to 821 mg/dL (p<0.0001). At baseline 46/63 (73%) patients had a serum IgM >3,000 mg/dL versus 4/63 (6%) patients at best response (p<0.0001). At best response, median bone marrow involvement declined from 60% to 20% (p<0.0001), and the median hemoglobin level increased from 10.5 to 14.2 g/dL (p<0.0001). The impact of MYD88 and CXCR4 mutation status on responses and time to at least a minor (overall) and PR or better (major) response are shown in Table 1.Figure 1 shows the Kaplan Meier curves for progression free survival (PFS) for all study participants (A), and those genotyped by MYD88 and CXCR4 mutation status (B). With a median study follow-up of 47.1 months, the median PFS for patients with MYD88MutCXCR4WT has not been reached. By comparison, the median PFS was 45 months for patients with MYD88MutCXCR4Mut, and 21 months for those with MYD88WTCXCR4WT (Log-rank p=0.0093 for 3-way comparison). Three patients died due to disease progression.Adverse events (Grade >2) that were at least possibly related to protocol therapy in >5% of patients during protocol therapy were as follows: anemia (n=4); atrial fibrillation (n=6); GERD (n=5); hypertension (n=5); neutropenia (n=14); pneumonia (n=6); skin infection (n=3); thrombocytopenia (n=9). Seven patients (11%) had atrial arrhythmia [Grade 1 (n=1); Grade 2 (n=5); Grade 3 (n=1)] on ibrutinib. Six of these patients continued ibrutinib with medical management for their atrial arrhythmia. Four patients came off protocol therapy for toxicity: atrial fibrillation (n=1); infection not related to drug therapy (n=1), procedure related hematoma (n=1), and thrombocytopenia (n=1). The findings from the long-term follow-up of this pivotal study confirm that ibrutinib is highly active in symptomatic patients with relapsed and refractory WM, and produces durable responses. Prolonged ibrutinib therapy is associated with improvements in categorical responses, including attainment of VGPR. Ibrutinib response activity and PFS are impacted by MYD88 and CXCR4 mutation status in this patient population. (ClinicalTrials.gov number, NCT01614821.) [Display omitted] DisclosuresTreon:Pharmacyclics: Consultancy, Research Funding. Laubach:Novartis, Takeda, Celgene: Consultancy; Novartis, Takeda, Celgene, Onyx: Research Funding. Castillo:Pharmacyclics: Consultancy, Research Funding; Abbvie: Research Funding; Millennium: Research Funding; Janssen: Consultancy, Research Funding. Palomba:Merck: Consultancy. Advani:Pharmacyclics: Consultancy; Pharmacyclics: Research Funding; Janssen: Research Funding; Infinity: Research Funding; Juno Therapeutics: Consultancy; Agensys: Research Funding; Celgene: Research Funding; Nanostring: Consultancy; Cell Medica: Research Funding; Genentech: Research Funding; Merck: Research Funding; Bristol-Myers Squibb: Consultancy, Research Funding; Gilead: Consultancy; Seattle Genetics: Research Funding; Bayer Healthcare Pharmaceuticals: Research Funding; FortySeven: Research Funding; Spectrum: Consultancy; Sutro: Consultancy; Regeneron: Research Funding; Millennium: Research Funding; Kura: Research Funding.

Molecular Characterization of Waldenström's Macroglobulinemia Patients Using Peripheral Blood Cell-Free Tumor DNA

BackgroundMutational characterization of Waldenström's macroglobulinemia (WM) currently relies on DNA from CD19-selected cells derived from bone marrow (BM) aspirates, which is an invasive technique, associated with significant patient discomfort. Peripheral blood cell-free tumour DNA (cf or ctDNA) has been recently shown to be a powerful non-invasive molecular biomarker in monitoring tumor status in several cancers. In this study, we aimed to characterize the mutational status of WM/IgM MGUS patients by using peripheral blood plasma-derived cfDNA and using matched tumor DNA (tDNA) from BM-CD19+ selected cells as a control, in order to determine whether peripheral blood , by means of cfDNA, can be used as an additional diagnostic tool in identifying the mutational profile of WM.MethodsA total of 30 consecutive patients with IgM monoclonal gammopathies were included in this study. All patients gave a written informed consent for sample collection and analysis. Peripheral blood (10-12mL) was collected in EDTA tubes and DNA was extracted using the MagMax cell free DNA isolation kit (ThermoFisher Scientific). cfDNA concentration was measured using the Qubit fluorometer. The quantities of cfDNA varied between 1.5 ng/μL and 8 ng/μL. BM aspirates were collected at the same time with peripheral blood, and were processed for CD19 enrichment, using CD19 magnetic beads (Miltenyi Biotech), followed by DNA extraction (Invitrogen). The paired tDNA and cfDNA samples from the 30 patients were analyzed for the MYD88 L265P and for CXCR4 mutations. The presence of L265P mutation was initially assessed by Allele-Specific PCR (AS-PCR) and then confirmed with direct sequencing. The presence of CXCR4 mutations was assessed with direct sequencing.ResultsThe study included patients with symptomatic WM before initiation of any therapy (N=4) , with WM under therapy (N=4) or after completion of therapy (N=12), with asymptomatic WM (N=8) and with IgM MGUS (N=2). The median age of the patients was 70 years (range 22-87). The median bone marrow infiltration of the tested samples was 28% (range 5 to 90%) and median IgM levels were 1510 mg/dL (range 80 to 7310 mg/dL).In all, but one patient, (29/30) the L265P mutation was detected in both cfDNA and tDNA (100% concordance). This mutation was initially detected by AS-PCR which was validated by direct sequencing in all patients. Assessment of CXCR4 mutation status was feasible in 29 patients; in one patient CXCR4 sequencing was unsuccessful in both cfDNA and tDNA. Mutations in CXCR4 were detected in 24% (7/29) of patients. The pathogenic mutation S338X (rs104893626) was present in 2 (7%) patients and was identified in both cfDNA and tDNA. In one patient the L50X (1/29) truncating mutation was found in tDNA but not in cfDNA. Two patients harbored the F29L (2/29) mutation and another two (2/29) the P31T mutation, both in cfDNA and in tDNA; these two mutations have not been previously reported. Synonymous mutations were also found in 10% of the tested patients in both cfDNA and tDNA. Thus, the concordance for CXCR4 mutations identified by direct sequencing of cfDNA and tDNA was 97% (in 28/29 patients).ConclusionsOur study demonstrates that in patients with IgM monoclonal gammopathies peripheral blood cell-free DNA can be used as a non-invasive method to detect the MYD88 L265P mutation with excellent concordance to BM CD19+ derived tumor DNA. Furthermore, CXCR4 mutations could also be detected with high concordance to tDNA by direct sequencing. This method could be more cost effective, as it avoids the expenses and time needed for CD19 selection, either BM or peripheral blood derived. Peripheral blood cfDNA could be used as an initial test to assess the presence of MYD88 L265P and CXCR4 mutations, so that BM testing can be limited to patients with indeterminate results. Updated results will be presented in the meeting. Further investigation is ongoing in order to assess tumor dynamics using peripheral blood. DisclosuresTerpos:Janssen: Honoraria, Research Funding; Genesis/Celgene: Honoraria, Other: DMC member, Research Funding; Abbvie: Honoraria; Takeda: Honoraria, Other: SC member; Amgen: Honoraria, Other: SC member, Research Funding; GSK: Honoraria; BMS: Honoraria. Kastritis:Prothena: Honoraria; Janssen: Honoraria; Genesis pharma: Honoraria; Takeda: Honoraria; Amgen: Honoraria, Research Funding. Dimopoulos:Amgen Inc, Celgene Corporation, Janssen Biotech Inc, Onyx Pharmaceuticals, an Amgen subsidiary, Takeda Oncology: Consultancy, Honoraria, Other: Advisory Committee: Amgen Inc, Celgene Corporation, Janssen Biotech Inc, Onyx Pharmaceuticals, an Amgen subsidiary, Takeda Oncology; Novartis: Consultancy, Honoraria; Genesis Pharma: Research Funding.