Genetic Predictors of Mortality in Patients with Multiple Myeloma

Chromosomal defects in multiple myeloma

Multiple myeloma is a plasma cell neoplasm driven by primary (e.g. hyperdiploidy; IGH translocations) and secondary (e.g. 1q21 gains/amplifications; del(17p); MYC translocations) chromosomal events. These are important to detect as they influence prognosis, therapeutic response and disease survival. Currently, cytogenetic testing is most commonly performed by interphase fluorescence in situ hybridisation (FISH) on aspirated bone marrow samples. A number of variations to FISH methodology are available, including prior plasma cell enrichment and incorporation of immunophenotypic plasma cell identification. Other molecular methods are increasingly being utilised to provide a genome-wide view at high resolution (e.g. single nucleotide polymorphism (SNP) microarray analysis) and these can detect abnormalities in most cases. Despite their wide application at diagnostic assessment, both FISH and SNP-array have relatively low sensitivity, limiting their use for identification of prognostically significant low-level sub-clones or for disease monitoring. Next-generation sequencing is increasingly being used to detect mutations and new FISH techniques such as by flow cytometry are in development and may address some of the current test limitations. Here we review the primary and secondary cytogenetic aberrations in myeloma and discuss the range of techniques available for their assessment.

Cytogenetic, Clinical, Hematologic, Demographic, Immunohistochemical, and Flow Cytometry Characteristics of Patients with Plasma Cell Neoplasm in Five Years: A First Report from Iran

Background

The aggregation of clonal plasma cells causes plasma cell neoplasms, which vary in severity and clinical outcomes. The present research focused on the epidemiological, clinical, immunologic, and cytogenetic characteristics of plasma cell neoplasms.

Methods

In this five-year retrospective cross-sectional study, demographic information such as age and sex, calcium elevation, renal insufficiency, anemia, and bone lesion (CRAB) characteristics, as well as laboratory data including bone marrow and peripheral blood film results, immunohistochemistry, flow cytometry, and cytogenetic study outcomes were collected at Shiraz University of Medical Sciences, Shiraz, Iran. The collected data were analyzed using SPSS Statistics software (version 20.0). Descriptive statistics were reported as numbers, percentages, and mean±SD.

Results

417 newly diagnosed plasma cell neoplasm patients were confirmed by bone marrow or other tissue biopsy tests. 279 patients were men (66.9%). The most prevalent age group was 60-64 years old (18.46%). Plasma cell myeloma (PCM) affected 355 (85.13%) patients, while monoclonal gammopathy of undetermined significance (MGUS) affected 6 (1.43%) patients. Solitary plasmacytoma was seen in 56 (13.42%) patients. At the time of diagnosis, 119 (33.52%) of 355 PCM patients were asymptomatic, whereas 236 (66.47%) patients had at least one CRAB symptom, 55 (15.49%) had two or more, and 14 (3.94%) had three or more. There were 7 (1.97%) cases of amyloidosis. Cytogenetic abnormalities were found in 51.28% (40/78) of the patients. Twenty-one individuals (52.5%) were hyperdiploid with multiple trisomy, while 19 (47.50%) were not.

Conclusion

When diagnosed, Iranian PCM patients might have more advanced disease. PCM was more prevalent in young adults, and hyperdiploid was the most common cytogenetic finding in this investigation.

Optical Genome Mapping Reveals the Complex Genetic Landscape of Myeloma

Fluorescence in situ hybridization (FISH) on enriched CD138 plasma cells is the standard method for identification of clinically relevant genetic abnormalities in multiple myeloma. However, FISH is a targeted analysis that can be challenging due to the genetic complexity of myeloma. The aim of this study was to evaluate the potential of optical genome mapping (OGM) to detect clinically significant cytogenetic abnormalities in myeloma and to provide larger pangenomic information. OGM and FISH analyses were performed on CD138-purified cells of 20 myeloma patients. OGM successfully detected structural variants (SVs) (IGH and MYC rearrangements), copy number variants (CNVs) (17p/TP53 deletion, 1p deletion and 1q gain/amplification) and aneuploidy (gains of odd-numbered chromosomes, monosomy 13) classically expected with myeloma and led to a 30% increase in prognosis yield at our institution when compared to FISH. Despite challenges in the interpretation of OGM calls for CNV and aneuploidy losses in non-diploid genomes, OGM has the potential to replace FISH as the standard of care analysis in clinical settings and to efficiently change how we identify prognostic and predictive markers for therapies in the future. To our knowledge, this is the first study highlighting the feasibility and clinical utility of OGM in myeloma.

Population pharmacokinetics and exposure-response analyses of daratumumab plus pomalidomide/dexamethasone in relapsed or refractory multiple myeloma

AIM

A population pharmacokinetic (PPK) model was developed to characterize pharmacokinetics (PK) of subcutaneous or intravenous daratumumab administration in a new indication (i.e., combination with pomalidomide and dexamethasone [D-Pd] in patients with relapsed or refractory multiple myeloma [RRMM]). Analyses were conducted to explore exposure-response (E-R) relationships for efficacy and select treatment-emergent adverse events (TEAEs).

METHODS

The PPK analysis included pooled data from the D-Pd cohorts of the phase 3 APOLLO and phase 1b EQUULEUS studies. Covariates were evaluated in the PPK model. Model-predicted exposures to daratumumab were compared between covariate subgroups of interest and used to investigate relationships between daratumumab exposure and efficacy and safety in APOLLO.

RESULTS

The PPK analysis included 1146 daratumumab PK samples from 239 patients (APOLLO, n = 140; EQUULEUS, n = 99). Observed concentration-time data of daratumumab were well described by a two-compartment PPK model with first-order absorption and parallel linear and nonlinear elimination pathways. Treatment with D-Pd provided similar daratumumab PK characteristics versus historical daratumumab monotherapy. The E-R dataset contained data from 290 APOLLO patients (D-Pd, n = 140; Pd, n = 150). The PK-efficacy relationship of daratumumab supported improved progression-free survival for patients in the D-Pd group vs. the Pd group. Additionally, TEAEs did not increase with increasing PK exposure in the D-Pd group.

CONCLUSIONS

The PPK and E-R analyses support the daratumumab subcutaneous 1800 mg dosing regimen in combination with Pd for treatment of patients with RRMM. No dose adjustment is recommended in this indication for any of the investigated factors, none of which had clinically relevant effects on daratumumab PK.

Chemical biology and pharmacology of histone lysine methylation inhibitors

Histone lysine methylation is a post-translational modification that plays a key role in the epigenetic regulation of a broad spectrum of biological processes. Moreover, the dysregulation of histone lysine methyltransferases (KMTs) has been implicated in the pathogenesis of several diseases particularly cancer. Due to their pathobiological importance, KMTs have garnered immense attention over the last decade as attractive therapeutic targets. These endeavors have culminated in tens of chemical probes that have been used to interrogate many aspects of histone lysine methylation. Besides, over a dozen inhibitors have been advanced to clinical trials, including the EZH2 inhibitor tazemetostat approved for the treatment of follicular lymphoma and advanced epithelioid sarcoma. In this Review, we highlight the chemical biology and pharmacology of KMT inhibitors and targeted protein degraders focusing on the clinical development of EZH1/2, DOT1L, Menin-MLL, and WDR5-MLL inhibitors. We also briefly discuss the pharmacologic targeting of other KMTs.