+1q: amplifying the bad genes in myeloma

Pathogenesis, clinical characteristics and personalized managements of multiple myeloma with chromosome 1 abnormalities

Multiple myeloma (MM) is a biologically heterogeneous malignancy defined by the proliferation of monoclonal plasma cells. Despite the tremendous advancement in MM treatment over the past decades, relapse remains a major problem which is inevitable for most patients. In particular, a partial of patients with early relapse and poor outcomes are classified as a high-risk group. Apart from the clinical stage, genetic aberrations are now recognized as important prognostic factors for identifying high-risk patients. Chromosome 1 abnormalities (C1As), particularly 1q21 gain or amplification, have been identified as common genetic aberrations in patients with MM and are often considered unfavorable prognostic markers for progression-free survival and overall survival. However, more effective therapeutic approaches are still needed to overcome the negative impact of C1As. Therefore, we summarize the prevalence, pathogenesis, clinical significance and present therapeutic condition of C1As in MM, and attempt to conclude the precise and personalized management for patients with C1As.

Prognostic significance of acquired 1q22 gain in multiple myeloma

Gain of 1q22 at diagnosis portends poorer outcomes in multiple myeloma (MM), but the prognostic significance of acquired 1q22 gain is unknown. We identified 63 MM patients seen at Mayo Clinic from 1/2004 to 12/2019 without 1q22 gain at diagnosis who acquired it during follow up and compared them to 63 control patients who did not acquire 1q22 gain with similar follow up. We also compared outcomes in the acquired 1q22 gain group with outcomes in 126 patients with 1q22 gain present at diagnosis. The incidence of acquired 1q22 gain was 6.1% (median follow-up 6.8 years); median time to acquisition was 5.0 years (range: 0.7-11.5 years). Abnormalities on baseline fluorescence in situ hybridization (FISH) included trisomies (54%) and monosomy 13 (39%); 16 (25%) had high-risk (HR) translocations or del(17p). Median progression-free survival with front line therapy was 29.5 months in patients with acquired 1q22 gain, versus 31.4 months in control patients (p = .34) and 31.2 months in patients with de novo 1q22 gain (p = .04). Median overall survival (OS) from diagnosis was 10.9 years in patients with acquired 1q22 gain, versus 13.0 years in control patients (p = .03) and 6.3 years in patients with de novo 1q22 gain (p = .01). Presence of HR FISH at baseline increased risk of 1q22 gain acquisition. We demonstrate that acquisition of 1q22 gain is a significant molecular event in MM, associated with reduced OS. Among HR patients for whom this clonal evolution is determined, a risk-adapted approach and/or clinical trial should be considered.

Genome Instability in Multiple Myeloma: Facts and Factors

Multiple myeloma (MM) is a malignant neoplasm of terminally differentiated immunoglobulin-producing B lymphocytes called plasma cells. MM is the second most common hematologic malignancy, and it poses a heavy economic and social burden because it remains incurable and confers a profound disability to patients. Despite current progress in MM treatment, the disease invariably recurs, even after the transplantation of autologous hematopoietic stem cells (ASCT). Biological processes leading to a pathological myeloma clone and the mechanisms of further evolution of the disease are far from complete understanding. Genetically, MM is a complex disease that demonstrates a high level of heterogeneity. Myeloma genomes carry numerous genetic changes, including structural genome variations and chromosomal gains and losses, and these changes occur in combinations with point mutations affecting various cellular pathways, including genome maintenance. MM genome instability in its extreme is manifested in mutation kataegis and complex genomic rearrangements: chromothripsis, templated insertions, and chromoplexy. Chemotherapeutic agents used to treat MM add another level of complexity because many of them exacerbate genome instability. Genome abnormalities are driver events and deciphering their mechanisms will help understand the causes of MM and play a pivotal role in developing new therapies.

Prevalence and characteristics of myeloproliferative neoplasms with concomitant monoclonal gammopathy

Of BCR-ABL negative myeloproliferative neoplasm (MPN) patients, 3-14 % display a concomitant monoclonal gammopathy (MGUS). Nonetheless, literature on co-occurring MPN and MGUS is scarce, the molecular underpinnings are unknown and it is unclear whether patients require a specific management. Here, we compared the clinical and genetic features of MPN patients with and without concomitant MGUS. Of 114 MPN patients prospectively studied by serum immunofixation (median age, 67 years; 36.0 % essential thrombocythemia [ET], 24.6 % polycythemia vera [PV], 11.4 % secondary myelofibrosis [sMF], 28.1 % primary myelofibrois [PMF]; 73.7 % JAK2 V617F positive), 10 (9 %) harbored an M-protein. No relevant clinical differences existed between MPN patients with or without M-protein. Seven additional MPN/MGUS patients were retrospectively identified in our MPN registry, yielding a total of 17 patients (7 ET, 3 PV, 3 sMF, 4 PMF). One patient developed multiple myeloma (MM) and one smoldering MM. Seven of 12 patients analyzed carried mutations (e.g. in ASXL1 or TET2) in addition to those in JAK2 or CALR, and 4 of 10 patients showed aberrant cytogenetics. M-protein was mainly IgG (12/17), followed by IgM (4/17). In the two patients that underwent allogeneic stem cell transplantation mutant JAK2 and M-protein were no longer detectable post-transplant. In conclusion, MGUS prevalence in our cohort was in the range of previous reports and at most slightly higher than expected in the general population. MGUS presence did not correlate with a specific MPN entity, clinical features or genetic alterations. Our observations suggest that there is no strong clinical or biological relationship between the occurrence of MGUS and MPN.

Remodeling and destabilization of chromosome 1 pericentromeric heterochromatin by SSX proteins

Rearrangement of the 1q12 pericentromeric heterochromatin and subsequent amplification of the 1q arm is commonly associated with cancer development and progression and may result from epigenetic deregulation. In many premalignant and malignant cells, loss of 1q12 satellite DNA methylation causes the deposition of polycomb factors and formation of large polycomb aggregates referred to as polycomb bodies. Here, we show that SSX proteins can destabilize 1q12 pericentromeric heterochromatin in melanoma cells when it is present in the context of polycomb bodies. We found that SSX proteins deplete polycomb bodies and promote the unfolding and derepression of 1q12 heterochromatin during replication. This further leads to segregation abnormalities during anaphase and generation of micronuclei. The structural rearrangement of 1q12 pericentromeric heterochromatin triggered by SSX2 is associated with loss of polycomb factors, but is not mediated by diminished polycomb repression. Instead, our studies suggest a direct effect of SSX proteins facilitated though a DNA/chromatin binding, zinc finger-like domain and a KRAB-like domain that may recruit chromatin modifiers or activate satellite transcription. Our results demonstrate a novel mechanism for generation of 1q12-associated genomic instability in cancer cells.

Advanced forms of MPNs are accompanied by chromosomal abnormalities that lead to dysregulation of TP53

The Philadelphia chromosome-negative myeloproliferative neoplasms (MPNs), including polycythemia vera (PV), essential thrombocythemia (ET), and the prefibrotic form of primary myelofibrosis (PMF), frequently progress to more overt forms of MF and a type of acute leukemia termed MPN-accelerated phase/blast phase (MPN-AP/BP). Recent evidence indicates that dysregulation of the tumor suppressor tumor protein p53 (TP53) commonly occurs in the MPNs. The proteins MDM2 and MDM4 alter the cellular levels of TP53. We investigated in 1,294 patients whether abnormalities involving chromosomes 1 and 12, which harbor the genes for MDM4 and MDM2, respectively, and chromosome 17, where the gene for TP53 is located, are associated with MPN disease progression. Gain of 1q occurred not only in individuals with MPN-BP but also in patients with PV and ET, who, with further follow-up, eventually evolve to either MF and/or MPN-BP. These gains of 1q were most prevalent in patients with a history of PV and those who possessed the JAK2V617F driver mutation. The gains of 1q were accompanied by increased transcript levels of MDM4 In contrast, 12q chromosomal abnormalities were exclusively detected in patients who presented with MF or MPN-BP, but were not accompanied by further increases in MDM2/MDM4 transcript levels. Furthermore, all patients with a loss of 17p13, which leads to a deletion of TP53, had either MF or MPN-AP/BP. These findings suggest that gain of 1q, as well as deletions of 17p, are associated with perturbations of the TP53 pathway, which contribute to MPN disease progression.