In this JCO Article Insights episode, Michael Hughes summarizes "International Myeloma Society and International Myeloma Working Group Consensus Recommendations on the Definition of High-Risk Multiple Myeloma" by Avet-Loiseau et al. published on June 09, 2025 along with an interview with author Dr Nikhil C. Munshi, MD.

TRANSCRIPT

Michael Hughes: Welcome to this episode of JCO Article Insights. This is Michael Hughes, JCO's editorial fellow. Today I am interviewing Dr. Nikhil Munshi on the "International Myeloma Society and International Myeloma Working Group Consensus Recommendations on the Definition of High-Risk Multiple Myeloma" by Avet-Loiseau et al.

At the time of this recording, our guest has disclosures that will be linked in the transcript.

While some patients with multiple myeloma live for decades after treatment, others exhibit refractory or rapidly relapsing disease irrespective of treatment administered. We term this "high-risk myeloma." Multiple risk stratification systems have been created, starting with the Durie-Salmon system in 1975 and evolving with the advent of novel therapeutics and novel treatment approaches.

In 2015, the Revised International Staging System (R-ISS) was introduced, which incorporated novel clinical and cytogenetic markers and remained, until recently, a mainstay of risk stratification in newly diagnosed disease. Myeloma as a field has, just in the past few years, though, undergone explosive changes. In particular, we have seen groundbreaking advances not only in treatments - the introduction of anti-CD38 agents and the advent of cellular and bispecific therapies - but also in diagnostic technology and our understanding of the genetic lesions in myeloma.

This has led to the proliferation of numerous trials employing different definitions of high-risk myeloma, a burgeoning problem for patients and providers alike, and has prompted attempts to consolidate definitions and terminology. Regarding cytogenetic lesions, at least, Kaiser et al's federated meta-analysis of 24 therapeutic trials, published here in the JCO in February of 2025 and recently podcasted in an interview with associate editor Dr. Suzanne Lentzsch, posited a new cytogenetic classification system to realize a shared platform upon which we might contextualize those trial results.

This article we have here by Dr. Avet-Loiseau, Dr. Munshi, and colleagues, published online in early June of this year and hot off the presses, is the definitive joint statement from the International Myeloma Society (IMS) and the International Myeloma Working Group (IMWG). What is high-risk multiple myeloma for the modern era?

The IMS and IMWG Genomics Workshop was held in July 2023 and was attended by international myeloma experts, collaborating to reach consensus based on large volumes of data presented and shared. The datasets included cohorts from the Intergroupe Francophone du Myélome (IFM); the HARMONY project, comprised of multiple European academic trials; the FORTE study, findings from which solidified KRd as a viable induction regimen; the Grupo Español de Mieloma Múltiple (GEM) and the PETHEMA Foundation; the German-Speaking Myeloma Multicenter Group (GMMG); the UK-based Myeloma XI, findings from which confirmed the concept of lenalidomide maintenance; Emory 1000, a large, real-world dataset from Emory University in Atlanta; the Multiple Myeloma Research Foundation Clinical Outcomes in Multiple Myeloma to Personal Assessment of Genetic Profile (CoMMpass) dataset; and some newly diagnosed myeloma cohorts from the Mayo Clinic.

Data were not pooled for analyses and were assessed individually - that is to say, with clear a priori understanding of whence the data had been gathered and for what original purposes. Consensus on topics was developed based on the preponderance of data across studies and cohorts.

In terms of results, substantial revisions were made to the genomic staging of high-risk multiple myeloma, and these can be sorted into three major categories: A) alterations to the tumor suppressor gene TP53; B) translocations involving chromosome 14: t(14;16) (c-MAF overexpression), t(14;20) (MAFB overexpression), and t(4;14) (NSD2 overexpression); and C) chromosome 1 abnormalities: deletions of 1p or additional copies of 1q.

In terms of category A, TP53 alterations: Deletion of 17p is present in up to 10% of patients at diagnosis and is enriched in relapsed or refractory disease. This is well-documented as a high-risk feature, but the proportion of the myeloma cells with deletion 17p actually impacts prognosis. GEM and HARMONY data analyses confirmed the use of 20% clonal cell fraction as the optimal threshold value for high-risk disease. That is to say, there must be the deletion of 17p in at least 20% of the myeloma cells on a FISH-analysis of a CD138-enriched bone marrow sample to qualify as high-risk disease.

TP53 mutations can also occur. Inactivating mutations appear to have deleterious effects similar to chromosomal losses, and the biallelic loss of TP53, however it occurs, portends particularly poor prognosis. This effect is seen across Myeloma XI, CoMMpass, and IFM cohorts. Biallelic loss is rare, it appears to occur in only about 5% of patients, but next-generation sequencing is nevertheless recommended in all myeloma patients.

Category B, chromosome 14 translocations: Translocation t(14;16) occurs in about 2% to 3% of patients with newly diagnosed disease. In the available data, primarily real-world IFM data, t(14;16) almost always occurs with chromosome 1 abnormalities. Translocation t(4;14) occurs in about 10% to 12% of newly diagnosed disease, but only patients with specific NSD2 alterations are, in fact, at risk of worse prognosis, which clinically appears to be about one in every three of those patients. And so together, the CoMMpass and Myeloma XI data suggest that translocation t(4;14) only in combination with deletion 1p or gain or amplification of 1q correlates with worse prognosis.

Translocation t(14;20) occurs in only 2% of newly diagnosed disease. Similar to translocation t(4;14), it doesn't appear to have an effect on prognosis, except if the translocation co-occurs with chromosome 1 lesions, in which case patients do fare worse.

Overall, these three translocations - t(14;16), t(4;14), and t(14;20) - should be considered high-risk only if chromosome 1 aberrations are also present. In terms of those chromosome 1 aberrations, category C, first deletions of 1p: Occurring in about 13% to 15% of newly diagnosed disease, deletion 1p eliminates critical cell checkpoints and normal apoptotic signaling. In the IFM and CoMMpass dataset analyses, biallelic deletion of 1p and monoallelic deletion of 1p co-occurring with additional copies of 1q denote high-risk.

In terms of the other aberration in chromosome 1 possible in myeloma, gain or amplification of 1q: This occurs in up to 35% to 37% of newly diagnosed disease. It upregulates CKS1B, which is a cyclin-dependent kinase, and ANP32E, a histone acetyltransferase inhibitor. GEM and IFM data suggest that gain or amplification of 1q - there was no clear survival detriment to amplification - is best considered as a high-risk feature only in combination with the other risk factors as above.

Now, in terms of any other criteria for high-risk disease, there remains one other item, and that has to do with tumor burden. There has been a consensus shift, really, in both the IMS and IMWG to attempt to develop a definition of high-risk disease which is based on biologic features rather than empirically observed and potentially temporally dynamic features, such as lactate dehydrogenase. Beta-2 microglobulin remains an independent high-risk indicator, but care must be taken when measuring it, as renal dysfunction can artificially inflate peripheral titers. The consensus conclusion was that a beta-2 microglobulin of at least 5.5 without renal failure should be considered high-risk but should not preclude detailed genomic profiling.

So, in conclusion, the novel 2025 IMS-IMWG risk stratification system for myeloma is binary. It's either high-risk disease or standard-risk disease. It's got four criteria. Number one, deletion 17p and/or a TP53 mutation. Clonal cell fraction cut-off, remember, is 20%. Or number two, an IGH translocation - t(4;14), t(14;16), t(14;20) - with 1q gain and/or deletion of 1p. Or a monoallelic deletion of 1p with 1q additional copies or a biallelic deletion of 1p. Or a beta-2 microglobulin of at least 5.5 only when the creatinine is normal.

This is a field-defining work that draws on analyses from across the world to put forward a dominant definition of high-risk disease and introduces a new era of biologically informed risk assessment in myeloma.

Now, how does this change our clinical approach? FISH must be performed on CD138-enriched samples and should be performed for all patients. Next-generation sequencing should also be performed on all patients. Trials will hopefully now begin to include this novel d