Chromosome 8q24.1/c-MYC abnormality: a marker for high-risk myeloma

Prognostic Implications of Circulating Plasma Cell Percentage in Multiple Myeloma and Primary Plasma Cell Leukemia Defined by New Criteria

INTRODUCTION

The definition of primary plasma cell leukemia (pPCL) has been revised from ≥20% to ≥5% circulating plasma cells (CPC). However, the precise prognosis associated with CPC remains controversial. This study aimed to investigate prognostic biomarkers for myeloma patients based on CPC presence.

METHODS

A comprehensive analysis was conducted on 309 consecutive patients diagnosed with either multiple myeloma or pPCL, utilizing peripheral blood smears stained with Wright-Giemsa.

RESULTS

Patients were grouped by CPC percentage: 0% (221, 71.5%), 1-4% (49, 15.9%), 5-19% (16, 5.2%), ≥20% (23, 7.4%). CPC >5% correlated with unfavorable characteristics, including anemia, renal dysfunction, and advanced International Staging System. Common cytogenetic abnormalities such as 1q21 amplification, 17p deletion, and Myc rearrangement were prevalent among CPC-positive patients. Median progression-free survival (PFS) and overall survival (OS) were shorter in patients with CPC ≥5% (29.47 vs. 10.03 months; 64.10 vs. 12.30 months). Additionally, PFS and OS were shorter in CPC-positive patients without autologous hematopoietic stem cell transplantation (ASCT) and those with response < partial remission to the first-line regimen. Furthermore, an association emerged between soft tissue-related extramedullary disease and inferior PFS, while Myc rearrangement correlated with abbreviated OS.

CONCLUSION

Biological characteristics displayed greater aggressiveness in patients with positive CPC, leading to significantly shorter PFS and OS. The presence of CPC, ASCT, and overall response rate were independent prognostic factors. While no new threshold for pPCL with CPCs is proposed, Myc rearrangements and CPC positivity could serve as ultra-high-risk factors for multiple myeloma.

INTRODUCTION

The definition of primary plasma cell leukemia (pPCL) has been revised from ≥20% to ≥5% circulating plasma cells (CPC). However, the precise prognosis associated with CPC remains controversial. This study aimed to investigate prognostic biomarkers for myeloma patients based on CPC presence.

METHODS

A comprehensive analysis was conducted on 309 consecutive patients diagnosed with either multiple myeloma or pPCL, utilizing peripheral blood smears stained with Wright-Giemsa.

RESULTS

Patients were grouped by CPC percentage: 0% (221, 71.5%), 1-4% (49, 15.9%), 5-19% (16, 5.2%), ≥20% (23, 7.4%). CPC >5% correlated with unfavorable characteristics, including anemia, renal dysfunction, and advanced International Staging System. Common cytogenetic abnormalities such as 1q21 amplification, 17p deletion, and Myc rearrangement were prevalent among CPC-positive patients. Median progression-free survival (PFS) and overall survival (OS) were shorter in patients with CPC ≥5% (29.47 vs. 10.03 months; 64.10 vs. 12.30 months). Additionally, PFS and OS were shorter in CPC-positive patients without autologous hematopoietic stem cell transplantation (ASCT) and those with response < partial remission to the first-line regimen. Furthermore, an association emerged between soft tissue-related extramedullary disease and inferior PFS, while Myc rearrangement correlated with abbreviated OS.

CONCLUSION

Biological characteristics displayed greater aggressiveness in patients with positive CPC, leading to significantly shorter PFS and OS. The presence of CPC, ASCT, and overall response rate were independent prognostic factors. While no new threshold for pPCL with CPCs is proposed, Myc rearrangements and CPC positivity could serve as ultra-high-risk factors for multiple myeloma.

Progression of Hodgkin lymphoma and plasma cell neoplasms: Report from the 2021 SH/EAHP Workshop

OBJECTIVES

To summarize cases submitted to the 2021 Society for Hematopathology/European Association for Haematopathology Workshop under the categories of progression of Hodgkin lymphoma, plasmablastic myeloma, and plasma cell myeloma.

METHODS

The workshop panel reviewed 20 cases covered in this session. In addition, whole-exome sequencing (WES) and whole-genome RNA expression analysis were performed on 10 submitted cases, including 6 Hodgkin lymphoma and 4 plasma neoplasm cases.

RESULTS

The cases of Hodgkin lymphoma included transformed cases to or from various types of B-cell lymphoma with 1 exception, which had T-cell differentiation. The cases of plasma cell neoplasms included cases with plasmablastic progression, progression to plasma cell leukemia, and secondary B-lymphoblastic leukemia. Gene variants identified by WES included some known to be recurrent in Hodgkin lymphoma and plasma cell neoplasm. All submitted Hodgkin lymphoma samples showed 1 or more of these mutations: SOCS1, FGFR2, KMT2D, RIT1, SPEN, STAT6, TET2, TNFAIP3, and ZNF217.

CONCLUSIONS

Better molecular characterization of both of these neoplasms and mechanisms of progression will help us to better understand mechanisms of progression and perhaps develop better prognostic models, as well as identifying novel therapeutic targets.

A simple additive staging system for newly diagnosed multiple myeloma

Risk stratification in multiple myeloma is important for prognostication, patient selection for clinical trials, and comparison of treatment approaches. We developed and validated a staging system that incorporates additional FISH abnormalities not included in the R-ISS and reflects the additive effects of co-occurring high-risk disease features. We first evaluated the prognostic value of predefined cytogenetic and laboratory abnormalities in 2556 Mayo Clinic patients diagnosed between February 2004 and June 2019. We then used data from 1327 patients to develop a risk stratification model and validated this in 502 patients enrolled in the MMRF CoMMpass study. On multivariate analysis, high-risk IgH translocations [risk ratio (RR): 1.7], 1q gain/amplification (RR: 1.4), chromosome17 abnormalities (RR: 1.6), ISS III (RR: 1.7), and elevated LDH (RR: 1.3) were independently associated with decreased overall survival (OS). Among 1327 evaluable patients, OS was 11.0 (95% CI: 9.2–12.6), 7.0 (95% CI: 6.3–9.2), and 4.5 (95% CI: 3.7–5.2) years in patients with 0 (stage I), 1 (stage II), and ≥2 (stage III) high-risk factors, respectively. In the MMRF cohort, median OS was 7.8 (95% CI: NR-NR), 6.0 (95% CI: 5.7-NR), and 4.3 (95% CI: 2.7-NR) years in the 3 groups, respectively (P < 0.001). This 5-factor, 3-tier system is easy to implement in practice and improves upon the current R-ISS.

The Prognostic Role of MYC Structural Variants Identified by NGS and FISH in Multiple Myeloma

PURPOSE

Structural variants (SV) of the MYC gene region are common in multiple myeloma and influence disease progression. However, the prognostic significance of different MYC SVs in multiple myeloma has not been clearly established.

EXPERIMENTAL DESIGN

We conducted a retrospective study of multiple myeloma comparing MYC SV subtypes identified by next-generation sequencing (NGS) and FISH to MYC expression and disease survival using 140 cases from Mayo Clinic and 658 cases from the MMRF CoMMpass study.

RESULTS

MYC SVs were found in 41% of cases and were classified into nine subtypes. A correlation between the presence of a MYC SV and increased MYC expression was identified. Among the nine MYC subtypes, the non-immunoglobulin (non-Ig) insertion subtype was independently associated with improved outcomes, while the Ig insertion subtype, specifically involving the IgL gene partner, was independently associated with poorer outcomes compared with other MYC SV subtypes. Although the FISH methodology failed to detect approximately 70% of all MYC SVs, those detected by FISH were associated with elevated MYC gene expression and poor outcomes suggesting a different pathogenic role for FISH-detected MYC subtypes compared with other MYC subtypes.

CONCLUSIONS

Understanding the impact of different MYC SVs on disease outcome is necessary for the reliable interpretation of MYC SVs in multiple myeloma. NGS approaches should be considered as a replacement technique for a more comprehensive evaluation of the multiple myeloma clone.

Lymphoproliferative Neoplasms With Plasmablastic Morphology: An Overview and Diagnostic Approach

CONTEXT.—

Plasmablastic morphology can be seen in several uncommon lymphoproliferative neoplasms. Sometimes it is difficult to distinguish these neoplasms from each other.

OBJECTIVE.—

To review the current understanding of major lymphoproliferative neoplasms with plasmablastic morphology; summarize the clinical, morphologic, immunophenotypic, cytogenetic, and molecular characteristics of each disease entity; and highlight a practical approach for differential diagnosis.

DATA SOURCES.—

Peer-reviewed medical literature and the authors' personal experience.

CONCLUSIONS.—

Plasmablastic lymphoma; plasmablastic myeloma; primary effusion lymphoma; human herpesvirus 8-positive diffuse large B-cell lymphoma, not otherwise specified; and anaplastic lymphoma kinase (ALK)-positive large B-cell lymphoma are major lymphoproliferative neoplasms with plasmablastic morphology. These neoplasms share many common morphologic and immunophenotypic characteristics. Definitive diagnosis requires a thorough understanding of disease phenotype and diagnostic criteria of each category. Recognition of expression pattern of Epstein-Barr virus-encoded small RNA, human herpesvirus 8, and ALK in these neoplasms is critical for diagnosis in cases with typical presentation. Additional ancillary studies and clinical findings may help in difficult cases.

Knowing the unknowns in high risk multiple myeloma

High risk multiple myeloma (HRMM) continues to portend worse outcomes despite the many advances in anti-myeloma therapeutics. The optimal approach to treatment is not clearly defined on account of the variable definitions of HRMM and the paucity of studies dedicated to the treatment of HRMM. In this review, we use a case-based approach to review the definitions of HRMM, and evaluate the evidence for induction, stem cell transplantation, and post-transplant therapy approaches for HRMM.

Whole genome sequencing demonstrates substantial pathophysiological differences of MYC rearrangements in patients with plasma cell myeloma and B-cell lymphoma

MYC rearrangements (MYCr) occur in several B-cell neoplasms and impact disease progression and overall survival. We used whole genome sequencing (WGS) and whole transcriptome sequencing (WTS) to analyze and compare MYCr in different B-cell neoplasms. The MYCr features of cases with plasma cell myeloma (PCM) (n = 88) showed distinct characteristics compared to cases with mature B-cell lymphomas (n = 62, including Burkitt lymphoma (BL), diffuse large B-cell lymphoma (DLBCL) and high grade lymphoma with MYC and BCL2 and/or BCL6 rearrangements (HGBL)): they were more complex and showed a wider variety of translocation partners and breakpoints. Additionally, unlike B-cell lymphomas, they showed no evidence of activation-induced deaminase (AID) involvement in the formation of MYCr with immunoglobolin heavy chain (IGH), indicating a different mechanism of origin. The different MYCr characteristics resulted in poor MYCr detection rates by fluorescence in situ hybridization of only 50% in PCM, compared to 94% in lymphoma.

MAP-kinase and JAK-STAT pathways dysregulation in plasmablastic lymphoma

Plasmablastic lymphoma (PBL) is an aggressive B-cell lymphoma with an immunoblastic/large cell morphology and plasmacytic differentiation. The differential diagnosis with Burkitt lymphoma (BL), plasma cell myeloma (PCM) and some variants of diffuse large B-cell lymphoma (DLBCL) may be challenging due to the overlapping morphological, genetic and immunophenotypic features. Furthermore, the genomic landscape in PBL is not well known. To characterize the genetic and molecular heterogeneity of these tumors, we investigated thirty-four PBL using an integrated approach, including fluorescence in situ hybridization, targeted sequencing of 94 B-cell lymphoma related genes, and copy-number arrays. PBL were characterized by high genetic complexity including MYC translocations (87%), gains of 1q21.1-q44, trisomy 7, 8q23.2-q24.21, 11p13-p11.2, 11q14.2-q25, 12p and 19p13.3-p13.13, losses of 1p33, 1p31.1-p22.3, 13q and 17p13.3-p11.2, and recurrent mutations of STAT3 (37%), NRAS and TP53 (33%), MYC and EP300 (19%) and CARD11, SOCS1 and TET2 (11%). Pathway enrichment analysis suggested a cooperative action between MYC alterations and MAPK (49%) and JAK-STAT (40%) signaling pathways. Of note, EBVnegative PBL cases had higher mutational and copy-number load and more frequent TP53, CARD11 and MYC mutations, whereas EBV-positive PBL tended to have more mutations affecting the JAK-STAT pathway. In conclusion, these findings further unravel the distinctive molecular heterogeneity of PBL identifying novel molecular targets and the different genetic profile of these tumors related to EBV infection.

Genetic Abnormalities in Multiple Myeloma: Prognostic and Therapeutic Implications

Some genetic abnormalities of multiple myeloma (MM) detected more than two decades ago remain major prognostic factors. In recent years, the introduction of cutting-edge genomic methodologies has enabled the extensive deciphering of genomic events in MM. Although none of the alterations newly discovered have significantly improved the stratification of the outcome of patients with MM, some of them, point mutations in particular, are promising targets for the development of personalized medicine. This review summarizes the main genetic abnormalities described in MM together with their prognostic impact, and the therapeutic approaches potentially aimed at abrogating the undesirable pathogenic effect of each alteration.

Double-Hit Primary Plasma Cell Leukemia with IGH/MYC and IGH/CCND1 Translocations

Primary plasma cell leukemia (pPCL) is an aggressive variant of multiple myeloma (MM). Immunoglobulin heavy chain (IgH) translocations are found in a majority of pPCL cases, supporting a central relation to pathogenesis of pPCL. However, two independent IgH translocations are barely detected at the onset of pPCL, and their significance is yet to be elucidated. Here, we report a case of an aggressive pPCL with simultaneous IGH/MYC and IGH/CCND1 translocations. A 73-year-old man was referred to our hospital with back pain and diagnosed as having pPCL with more than 50% circulating plasma cells. Cytogenetic analysis revealed 47, Y, t (X; 8;14) (q24; q24; q32), t (11; 14) (q13; q32), and +18. IGH/MYC and IGH/CCND1 translocations were confirmed by fluorescence in situ hybridization analysis. Bortezomib and dexamethasone treatment achieved rapid elimination of peripheral malignant plasma cells, and the patient maintained a partial response for 18 months. After biological relapse, he received salvage therapy with ixazomib, lenalidomide, and dexamethasone, followed by pomalidomide and dexamethasone, and exhibited stable disease for an additional 14 months. Although IGH/MYC translocation in association with dysregulation of antiapoptotic pathway leads to worse prognosis in lymphomas, the novel agent-based regimen showed good efficacy, suggesting that IGH/MYC plays a different role in the pathogenesis of MM. IGH/CCND1 and IGH/MYC translocations may have contributed to abrupt onset of pPCL in this case.

Implications of MYC Rearrangements in Newly Diagnosed Multiple Myeloma

PURPOSE

Rearrangements involving the MYC protooncogene are common in newly diagnosed multiple myeloma, but their prognostic significance is still unclear. The purpose of this study was to assess the impact of MYC rearrangement on clinical characteristics, treatment response, and survival in patients with newly diagnosed multiple myeloma.

EXPERIMENTAL DESIGN

This is a retrospective study including 1,342 patients seen in Mayo Clinic in Rochester, MN, from January 2006 to January 2018, who had cytogenetic testing by FISH at diagnosis, including MYC testing using the break apart FISH probe (8q24.1).

RESULTS

A rearrangement involving MYC was found in 8% of patients and was associated with elevated β2-microglobulin, ≥50% bone marrow plasma cells, IgA multiple myeloma, and the cooccurrence of trisomies. There were no differences in overall response rates between patients with and without MYC rearrangement when induction chemotherapy was proteasome inhibitor (PI)-based, immunomodulatory drug (IMiD)-based or PI + IMiD-based. Overall survival was shorter in patients with MYC rearrangement compared with patients without MYC rearrangement (5.3 vs. 8.0 years, P < 0.001). MYC rearrangement was associated with increased risk of death on multivariate analysis when high-risk cytogenetic abnormalities, ISS stage III, and ≥70 years of age were included (risk ratio: 1.5; P = 0.007).

CONCLUSIONS

MYC rearrangement is associated with high disease burden and is an independent adverse prognostic factor in patients with newly diagnosed multiple myeloma.

The novel protein homeostatic modulator BTX306 is active in myeloma and overcomes bortezomib and lenalidomide resistance

Small molecules targeting the cereblon-containing E3 ubiquitin ligase including thalidomide, lenalidomide, and pomalidomide modulate turnover of downstream client proteins and demonstrate pre-clinical and clinical anti-myeloma activity. Different drugs that engage with cereblon hold the potential of unique phenotypic effects, and we therefore studied the novel protein homeostatic modulator (PHM™) BTX306 with a unique thiophene-fused scaffold bearing a substituted phenylurea and glutarimide. This agent much more potently reduced human-derived myeloma cell line viability, with median inhibitory concentrations in the single nanomolar range versus micromolar values for lenalidomide or pomalidomide, and more potently activated caspases 3/8/9. While lenalidomide and pomalidomide induced greater degradation of Ikaros and Aiolos in myeloma cells, BTX306 more potently reduced levels of GSPT1, eRF1, CK1α, MCL-1, and c-MYC. Suppression of cereblon or overexpression of Aiolos or Ikaros induced relative resistance to BTX306, and this agent did not impact viability of murine hematopoietic cells in an in vivo model, demonstrating its specificity for human cereblon. Interestingly, BTX306 did show some reduced activity in lenalidomide-resistant cell line models but nonetheless retained its nanomolar potency in vitro, overcame bortezomib resistance, and was equipotent against otherwise isogenic cell line models with either wild-type or knockout TP53. Finally, BTX306 demonstrated strong activity against primary CD138-positive plasma cells, showed enhanced anti-proliferative activity in combination with bortezomib and dexamethasone, and was effective in an in vivo systemic model of multiple myeloma. Taken together, the data support further translational studies of BTX306 and its derivatives to the clinic for patients with relapsed and/or refractory myeloma. KEY MESSAGES: BTX306 has a unique thiophene-fused scaffold bearing phenylurea and glutarimide. BTX306 is more potent against myeloma cells than lenalidomide or pomalidomide. BTX306 overcomes myeloma cell resistance to lenalidomide or bortezomib in vitro. BTX306 is active against primary myeloma cells, and shows efficacy in vivo.

c-MYC expression and maturity phenotypes are associated with outcome benefit from addition of ixazomib to lenalidomide-dexamethasone in myeloma

OBJECTIVES

In the TOURMALINE-MM1 phase 3 trial in relapsed/refractory multiple myeloma, ixazomib-lenalidomide-dexamethasone (IRd) showed different magnitudes of progression-free survival (PFS) benefit vs placebo-Rd according to number and type of prior therapies, with greater benefit seen in patients with >1 prior line of therapy or 1 prior line of therapy without stem cell transplantation (SCT).

METHODS

RNA sequencing data were used to investigate the basis of these differences.

RESULTS

The PFS benefit of IRd vs placebo-Rd was greater in patients with tumors expressing high c-MYC levels (median not reached vs 11.3 months; hazard ratio [HR] 0.42; 95% CI, 0.26, 0.66; P < .001) compared with in those expressing low c-MYC levels (median 20.6 vs 16.6 months; HR 0.75; 95% CI, 0.42, 1.2). Expression of c-MYC in tumors varied based on the number and type of prior therapy received, with the lowest levels observed in tumors of patients who had received 1 prior line of therapy including SCT. These tumors also had higher expression levels of CD19 and CD81.

CONCLUSIONS

PFS analyses suggest that lenalidomide and ixazomib target tumors with different levels of c-MYC, CD19, and CD81 expression, thus providing a potential rationale for the differential benefits observed in the TOURMALINE-MM1 study. This trial was registered at www.clinicaltrials.gov as: NCT01564537.

MYC amplification on double minute chromosomes in plasma cell leukemia with double IGH/CCND1 fusion genes

In multiple myeloma (MM), MYC rearrangements that result in increased MYC expression are associated with an aggressive form of MM and adverse outcome. However, the consequences of MYC amplification in MM remain unclear. Here, we describe an unusual case of plasma cell leukemia (PCL) harboring MYC amplification on double minute chromosomes (dmin). A 79-year-old woman was initially diagnosed as having BJP-κ type MM with bone lesions. After seven months, the disease progressed to secondary PCL: leukocytes 49.1 × 10⁹/L with 77% plasma cells showing lymphoplasmacytic appearance. The bone marrow was infiltrated with 76% plasma cells immunophenotypically positive for CD38 and negative for CD45, CD19, CD20, and CD56. The karyotype by G-banding and spectral karyotyping was 48,XX,der(14)t(11;14)(q13;q32),+der(14)t(14;19)(q32;q13.1),+18,6~95dmin[15]/46,XX[5]. Fluorescence in situ hybridization detected multiple MYC signals on dmin and double IGH/CCND1 fusion signals on der(14)t(11;14) and der(14)t(14;19). Most plasma cells were diffusely and strongly positive for MYC and CCND1 by immunohistochemistry. The patient died of progressive disease after one week. MYC amplification led to high expression of MYC and rapid disease progression, indicating its clinical significance in the pathogenesis of MM/PCL. MYC amplification on dmin may be a very rare genetic event closely associated with the progression to PCL and coexistence of IGH/CCND1 fusions.

Mate pair sequencing outperforms fluorescence in situ hybridization in the genomic characterization of multiple myeloma

Fluorescence in situ hybridization (FISH) is currently the gold-standard assay to detect recurrent genomic abnormalities of prognostic significance in multiple myeloma (MM). Since most translocations in MM involve a position effect with heterogeneous breakpoints, we hypothesize that FISH has the potential to miss translocations involving these regions. We evaluated 70 bone marrow samples from patients with plasma cell dyscrasia by FISH and whole-genome mate-pair sequencing (MPseq). Thirty cases (42.9%) displayed at least one instance of discordance between FISH and MPseq for each primary and secondary abnormality evaluated. Nine cases had abnormalities detected by FISH that went undetected by MPseq including 6 tetraploid clones and three cases with missed copy number abnormalities. In contrast, 19 cases had abnormalities detected by MPseq that went undetected by FISH. Seventeen were MYC rearrangements and two were 17p deletions. MPseq identified 36 MYC abnormalities and 17 (50.0% of MYC abnormal group with FISH results) displayed a false negative FISH result. MPseq identified 10 cases (14.3%) with IgL rearrangements, a recent marker of poor outcome, and 10% with abnormalities in genes associated with lenalidomide response or resistance. In summary, MPseq was superior in the characterization of rearrangement complexity and identification of secondary abnormalities demonstrating increased clinical value compared to FISH.

Myc protein overexpression is a feature of progression and adverse prognosis in multiple myeloma

OBJECTIVE

Prognostic and predictive markers in multiple myeloma are continuously explored because of the heterogeneity of the tumor biology. Myc protein is the final product from activating MYC oncogene, but the prognostic impact in multiple myeloma is not well described.

METHODS

In a population-based cohort of 194 untreated, newly diagnosed patients with multiple myeloma, we assessed myc protein expression using CD138/myc immunohistochemical double stain and collected clinicopathological data.

RESULTS

Cases with myc protein expression ≥40% (mycHIGH ) had a median overall survival of 11 months compared to 48 months in cases of myc protein expression <40% (mycLOW ) (P < 0.01). MycHIGH was significantly correlated to R-ISS, high proliferation index, high percentage of plasma cell in bone marrow, plasmablastic morphology, high calcium level, and abnormal karyotype. In multivariate survival analyses, mycHIGH was independently associated with inferior overall survival with a hazard ratio of 2.5.

CONCLUSION

Our results indicate myc protein overexpression to be associated with advanced multiple myeloma and poor prognosis.

Linking transcriptional and genetic tumor heterogeneity through allele analysis of single-cell RNA-seq data

Characterization of intratumoral heterogeneity is critical to cancer therapy, as the presence of phenotypically diverse cell populations commonly fuels relapse and resistance to treatment. Although genetic variation is a well-studied source of intratumoral heterogeneity, the functional impact of most genetic alterations remains unclear. Even less understood is the relative importance of other factors influencing heterogeneity, such as epigenetic state or tumor microenvironment. To investigate the relationship between genetic and transcriptional heterogeneity in a context of cancer progression, we devised a computational approach called HoneyBADGER to identify copy number variation and loss of heterozygosity in individual cells from single-cell RNA-sequencing data. By integrating allele and normalized expression information, HoneyBADGER is able to identify and infer the presence of subclone-specific alterations in individual cells and reconstruct the underlying subclonal architecture. By examining several tumor types, we show that HoneyBADGER is effective at identifying deletions, amplifications, and copy-neutral loss-of-heterozygosity events and is capable of robustly identifying subclonal focal alterations as small as 10 megabases. We further apply HoneyBADGER to analyze single cells from a progressive multiple myeloma patient to identify major genetic subclones that exhibit distinct transcriptional signatures relevant to cancer progression. Other prominent transcriptional subpopulations within these tumors did not line up with the genetic subclonal structure and were likely driven by alternative, nonclonal mechanisms. These results highlight the need for integrative analysis to understand the molecular and phenotypic heterogeneity in cancer.

Protein targeting chimeric molecules specific for bromodomain and extra-terminal motif family proteins are active against pre-clinical models of multiple myeloma

Bromodomain and extraterminal (BET) domain containing protein (BRD)-4 modulates the expression of oncogenes such as c-myc, and is a promising therapeutic target in diverse cancer types. We performed pre-clinical studies in myeloma models with bi-functional protein-targeting chimeric molecules (PROTACs) which target BRD4 and other BET family members for ubiquitination and proteasomal degradation. PROTACs potently reduced the viability of myeloma cell lines in a time- and concentration-dependent manner associated with G₀/G₁ arrest, reduced levels of CDKs 4 and 6, increased p21 levels, and induction of apoptosis. These agents specifically decreased cellular levels of downstream BRD4 targets, including c-MYC and N-MYC, and a Cereblon-targeting PROTAC showed downstream effects similar to those of an immunomodulatory agent. Notably, PROTACs overcame bortezomib, dexamethasone, lenalidomide, and pomalidomide resistance, and their activity was maintained in otherwise isogenic myeloma cells with wild-type or deleted TP53. Combination studies showed synergistic interactions with dexamethasone, BH3 mimetics, and Akt pathway inhibitors. BET-specific PROTACs induced a rapid loss of viability of primary cells from myeloma patients, and delayed growth of MM1.S-based xenografts. Our data demonstrate that BET degraders have promising activity against pre-clinical models of multiple myeloma, and support their translation to the clinic for patients with relapsed and/or refractory disease.

Elotuzumab for the Treatment of Relapsed or Refractory Multiple Myeloma, with Special Reference to its Modes of Action and SLAMF7 Signaling

Elotuzumab, targeting signaling lymphocytic activation molecule family 7 (SLAMF7), has been approved in combination with lenalidomide and dexamethasone (ELd) for relapsed/refractory multiple myeloma (MM) based on the findings of the phase III randomized trial ELOQUENT-2 (NCT01239797). Four-year follow-up analyses of ELOQUENT-2 have demonstrated that progression-free survival was 21% in ELd versus 14% in Ld. Elotuzumab binds a unique epitope on the membrane IgC2 domain of SLAMF7, exhibiting a dual mechanism of action: natural killer (NK) cell-mediated antibody-dependent cellular cytotoxicity (ADCC) and enhancement of NK cell activity. The ADCC is mediated through engagement between Fc portion of elotuzumab and FcgRIIIa/CD16 on NK cells. Enhanced NK cell cytotoxicity results from phosphorylation of the immunoreceptor tyrosine-based switch motif (ITSM) that is induced via elotuzumab binding and recruits the SLAM-associated adaptor protein EAT-2. The coupling of EAT-2 to the phospholipase Cg enzymes SH2 domain leads to enhanced Ca²⁺ influx and MAPK/Erk pathway activation, resulting in granule polarization and enhanced exocytosis in NK cells. Elotuzumab does not stimulate the proliferation of MM cells due to a lack of EAT-2. The inhibitory effects of elotuzumab on MM cell growth are not induced by the lack of CD45, even though SHP-2, SHP-1, SHIP-1, and Csk may be recruited to phosphorylated ITSM of SLAMF7. ELd improves PFS in patients with high-risk cytogenetics, i.e. t(4;14), del(17p), and 1q21 gain/amplification. Since the immune state is paralytic in advanced MM, the efficacy of ELd with minimal toxicity may bring forward for consideration of its use in the early stages of the disease.

How to Think About Risk in Myeloma

An integral part of myeloma therapy is risk stratification of newly diagnosed patients. This method involves a combination of staging and genetic risk assessment. Although survival has dramatically improved for patients with genetically defined, standard-risk myeloma, those with high-risk disease remain a therapeutic challenge. Current treatment approaches might include the use of combination therapy for induction and maintenance. Future approaches are expected to involve drugs that are "risk agnostic," such as monoclonal antibodies and immunotherapy.

CD24, CD27, CD36 and CD302 gene expression for outcome prediction in patients with multiple myeloma

Multiple myeloma (MM) is a B cell neoplasia characterized by clonal plasma cell (PC) proliferation. Minimal residual disease monitoring by multi-parameter flow cytometry is a powerful tool for predicting treatment efficacy and MM outcome. In this study, we compared CD antigens expression between normal and malignant plasma cells to identify new potential markers to discriminate normal from malignant plasma cells, new potential therapeutic targets for monoclonal-based treatments and new prognostic factors. Nine genes were significantly overexpressed and 16 were significantly downregulated in MMC compared with BMPC (ratio ≥2; FDR CD24, CD27, CD36 and CD302) was associated with a prognostic value in two independent cohorts of patients with MM (HM cohort and TT2 cohort, n=345). The expression level of these four genes was then used to develop a CD gene risk score that classified patients in two groups with different survival (P = 2.06E-6) in the HM training cohort. The prognostic value of the CD gene risk score was validated in two independent cohorts of patients with MM (TT2 cohort and HOVON65/GMMGHD4 cohort, n=282 patients). The CD gene risk score remained a prognostic factor that separated patients in two groups with significantly different overall survival also when using publicly available data from a cohort of relapsing patients treated with bortezomib (n=188). In conclusion, the CD gene risk score allows identifying high risk patients with MM based on CD24, CD27, CD36 and CD302 expression and could represent a powerful tool for simple outcome prediction in MM.

Evolutionary biology of high-risk multiple myeloma

The outcomes for the majority of patients with myeloma have improved over recent decades, driven by treatment advances. However, there is a subset of patients considered to have high-risk disease who have not benefited. Understanding how high-risk disease evolves from more therapeutically tractable stages is crucial if we are to improve outcomes. This can be accomplished by identifying the genetic mechanisms and mutations driving the transition of a normal plasma cell to one with the features of the following disease stages: monoclonal gammopathy of undetermined significance, smouldering myeloma, myeloma and plasma cell leukaemia. Although myeloma initiating events are clonal, subsequent driver lesions often occur in a subclone of cells, facilitating progression by Darwinian selection processes. Understanding the co-evolution of the clones within their microenvironment will be crucial for therapeutically manipulating the process. The end stage of progression is the generation of a state associated with treatment resistance, increased proliferation, evasion of apoptosis and an ability to grow independently of the bone marrow microenvironment. In this Review, we discuss these end-stage high-risk disease states and how new information is improving our understanding of their evolutionary trajectories, how they may be diagnosed and the biological behaviour that must be addressed if they are to be treated effectively.

RNA Polymerase I Inhibition with CX-5461 as a Novel Therapeutic Strategy to Target MYC in Multiple Myeloma

Dysregulation of MYC is frequently implicated in both early and late myeloma progression events, yet its therapeutic targeting has remained a challenge. Among key MYC downstream targets is ribosomal biogenesis, enabling increases in protein translational capacity necessary to support the growth and self-renewal programmes of malignant cells. We therefore explored the selective targeting of ribosomal biogenesis with the small molecule RNA polymerase (pol) I inhibitor CX-5461 in myeloma. CX-5461 induced significant growth inhibition in wild-type (WT) and mutant TP53 myeloma cell lines and primary samples, in association with increases in downstream markers of apoptosis. Moreover, Pol I inhibition overcame adhesion-mediated drug resistance and resistance to conventional and novel agents. To probe the TP53-independent mechanisms of CX-5461, gene expression profiling was performed on isogenic TP53 WT and knockout cell lines and revealed reduction of MYC downstream targets. Mechanistic studies confirmed that CX-5461 rapidly suppressed both MYC protein and MYC mRNA levels. The latter was associated with an increased binding of the RNA-induced silencing complex (RISC) subunits TARBP2 and AGO2, the ribosomal protein RPL5, and MYC mRNA, resulting in increased MYC transcript degradation. Collectively, these studies provide a rationale for the clinical translation of CX-5461 as a novel therapeutic approach to target MYC in myeloma.

Prognostic Significance of Mixed-Lineage Leukemia (MLL) Gene Detected by Real-Time Fluorescence Quantitative PCR Assay in Acute Myeloid Leukemia

Background

The overall prognosis of acute myeloid leukemia (AML) patients with mixed-lineage leukemia (MLL) gene-positivity is unfavorable. In this study, we evaluated the expression levels of the MLL gene in AML patients.

Material/Methods

We enrolled 68 MLL gene-positive patients out of 433 newly diagnosed AML patients, and 216 bone marrow samples were collected. Real-time fluorescence quantitative PCR (RQ-PCR) was used to precisely detect the expression levels of the MLL gene.

Results

We divided 41 patients into 2 groups according to the variation of MRD (minimal residual disease) level of the MLL gene. Group 1 (n=22) had a rapid reduction of MRD level to ≤10⁻⁴ in all samples collected in the first 3 chemotherapy cycles, while group 2 (n=19) had MRD levels constantly >10⁻⁴ in all samples collected in the first 3 chemotherapy cycles. Group 1 had a significantly better overall survival (p=0.001) and event-free survival (p=0.001) compared to group 2. Moreover, the patients with >10⁻⁴ MRD level before the start of HSCT (hematopoietic stem cell transplantation) had worse prognosis and higher risk of relapse compared to patients with ≤10⁻⁴ before the start of HSCT.

Conclusions

We found that a rapid reduction of MRD level to ≤10⁻⁴ appears to be a prerequisite for better overall survival and event-free survival during the treatment of AML. The MRD levels detected by RQ-PCR were basically in line with the clinical outcome and may be of great importance in guiding early allogeneic HSCT (allo-HSCT) treatment.

Direct inhibition of c-Myc-Max heterodimers by celastrol and celastrol-inspired triterpenoids

Many oncogenic signals originate from abnormal protein-protein interactions that are potential targets for small molecule inhibitors. However, the therapeutic disruption of these interactions has proved elusive. We report here that the naturally-occurring triterpenoid celastrol is an inhibitor of the c-Myc (Myc) oncoprotein, which is over-expressed in many human cancers. Most Myc inhibitors prevent the association between Myc and its obligate heterodimerization partner Max via their respective bHLH-ZIP domains. In contrast, we show that celastrol binds to and alters the quaternary structure of the pre-formed dimer and abrogates its DNA binding. Celastrol contains a reactive quinone methide group that promiscuously forms Michael adducts with numerous target proteins and other free sulfhydryl-containing molecules. Interestingly, triterpenoid derivatives lacking the quinone methide showed enhanced specificity and potency against Myc. As with other Myc inhibitors, these analogs rapidly reduced the abundance of Myc protein and provoked a global energy crisis marked by ATP depletion, neutral lipid accumulation, AMP-activated protein kinase activation, cell cycle arrest and apoptosis. They also inhibited the proliferation of numerous established human cancer cell lines as well as primary myeloma explants that were otherwise resistant to JQ1, a potent indirect Myc inhibitor. N-Myc amplified neuroblastoma cells showed similar responses and, in additional, underwent neuronal differentiation. These studies indicate that certain pharmacologically undesirable properties of celastrol such as Michael adduct formation can be eliminated while increasing selectivity and potency toward Myc and N-Myc. This, together with their low in vivo toxicity, provides a strong rationale for pursuing the development of additional Myc-specific triterpenoid derivatives.

MYC amplifications in myeloma cell lines: correlation with MYC-inhibitor efficacy

In multiple myeloma, elevated MYC expression is related to disease initiation and progression. We found that in myeloma cell lines, MYC gene amplifications were common and correlated with MYC mRNA and protein. In primary cell samples MYC mRNA levels were also relatively high; however gene copy number alterations were uncommon. Elevated levels of MYC in primary myeloma cells have been reported to arise from complex genetic aberrations and are more common than previously thought. Thus, elevated MYC expression is achieved differently in myeloma cell lines and primary cells. Sensitivity of myeloma cell lines to the MYC inhibitor 10058-F4 correlated with MYC expression, supporting that the activity of 10058-F4 was through specific inhibition of MYC.

An examination of clinical differences between carriers and non-carriers of chromosome 8q24 risk alleles in a New Zealand Caucasian population with prostate cancer

Background. Prostate cancer makes up approximately 15% of all cancers diagnosed in men in developed nations and approximately 4% of cases in developing nations. Although it is clear that prostate cancer has a genetic component and single nucleotide polymorphisms (SNPs) can contribute to prostate cancer risk, detecting associations is difficult in multi-factorial diseases, as environmental and lifestyle factors also play a role. In this study, specific clinical characteristics, environmental factors and genetic risk factors were assessed for interaction with prostate cancer.

Methods. A total of 489 prostate cancer cases and 427 healthy controls were genotyped for SNPs found on chromosome 8q24 and a genetic risk score was calculated. In addition the SNPs were tested for an association with a number of clinical and environmental factors.

Results. Age and tobacco use were positively associated, whilst alcohol consumption was negatively associated with prostate cancer risk. The following SNPs found on chromosome 8q24 were statistically significantly associated with prostate cancer: rs10086908, rs16901979; rs1447295and rs4242382. No association between Gleason score and smoking status, or between Gleason score and genotype were detected.

Conclusion. A genetic risk score was calculated based on the 15 SNPs tested and found to be significantly associated with prostate cancer risk. Smoking significantly contributed to the risk of developing prostate cancer, and this risk was further increased by the presence of four SNPs in the 8q24 chromosomal region.

Molecular Cytogenetic Analysis of Chromosome 8 Aberrations in Patients With Multiple Myeloma Examined in 2 Different Stages, at Diagnosis and at Progression/Relapse

BACKGROUND

The genome of multiple myeloma (MM) clonal plasma cells is characterized by genetic changes of prognostic importance. Disease progression is accompanied by a number of secondary chromosomal aberrations including chromosome 8. We focused on the detection of chromosome 8 aberrations in patients with MM who were examined at 2 different phases: diagnosis and progression/relapse.

PATIENTS AND METHODS

A total of 62 patients with MM were examined at the time of diagnosis and at relapse/progression. The median age was 64 years (range, 39-78 years); the study included 29 males and 33 females. We analyzed bone marrow samples for detecting aberrations on chromosome 8 by the fluorescence immunophenotyping and interphase cytogenetics as a tool for the investigation of neoplasms (FICTION) and fluorescence in situ hybridization methods with specific probes.

RESULTS

Chromosome 8 aberrations were detected in 24 (38.7%) patients at diagnosis and in 29 (46.8%) patients at progression/relapse. Only 5 (8%) patients developed additional chromosome 8 changes at progression/relapse. The aberrations were heterogeneous, involving numerical and structural changes of the MYC gene. Aberrations of the short arm of chromosome 8, involving the genes TRAIL-R1/-R2, were less frequent (4 of 62 patients, 6.4%). All aberrations of chromosome 8 were accompanied with additional changes and with an advanced clinical phase of the disease. This finding significantly influenced the overall survival of patients.

CONCLUSION

In the current study, chromosome 8 aberrations were highly heterogeneous, were presented at diagnosis in patients with advanced clinical stage, and were associated with worse overall survival. We have not confirmed the increase of frequency aberration of chromosome 8 in disease progression. The findings demonstrate the importance of fluorescence in situ hybridization examination of chromosome 8 in newly diagnosed patients with MM.

Interpretation of cytogenetic results in multiple myeloma for clinical practice

The interpretation of cytogenetic abnormalities in multiple myeloma (MM) is often a challenging task. MM is characterized by several cytogenetic abnormalities that occur at various time points in the disease course. The interpretation of cytogenetic results in MM is complicated by the number and complexity of the abnormalities, the methods used to detect them and the disease stage at which they are detected. Specific cytogenetic abnormalities affect clinical presentation, progression of smoldering multiple myeloma (SMM) to MM, prognosis of MM and management strategies. The goal of this paper is to provide a review of how MM is classified into specific subtypes based on primary cytogenetic abnormalities and to provide a concise overview of how to interpret cytogenetic abnormalities based on the disease stage to aid clinical practice and patient management.