Evolving Biomarkers Span Proteomic, Genomic Fields in Multiple Myeloma

Mark Bustoros, MBBCh

Several next-generation biomarkers are currently emerging in multiple myeloma (MM) that could lead to improved clinical management and outcomes, as well as enhanced precision medicine. “There are still a lot of things that are ongoing, and the myeloma field is evolving with new treatments. It’s a very interesting time for myeloma research in general and for patients with myeloma. There is a lot of interest to understand the disease better,” said Mark Bustoros, MBBCh, assistant professor of medicine at Weill Cornell Medicine, Cornell University, and the Division of Hematology and Medical Oncology at NewYork-Presbyterian Weill Cornell Medical Center.

MM is a hematologic malignancy characterized by proliferation of abnormal plasma cells in the bone marrow. Diagnosis and risk stratification of MM depend on primary biomarkers, M protein, ß2-microglobulin, albumin, and lactate dehydrogenase.¹ Biomarker assessment is performed using electrophoresis, fluorescence in situ hybridization (FISH), and imaging to diagnose and risk-stratify the disease.²

Biomarkers in MM also contribute to determining the stage of the disease in patients. The International Staging System (ISS) and, most recently, the Revised International Staging System (R-ISS) are used to stage patients.³ The R-ISS incorporates cytogenetic abnormalities, signifying the importance of the involvement of genomics in the prognosis of patients.^1-3

Discussing the current staging system in the era of novel treatment options in MM, Bustoros said that “with the advent of the new therapies—especially the monoclonal antibodies such as daratumumab [Darzalex], chimeric antigen receptor [CAR] T, and other immunotherapies— [the relationship between the staging system and novel treatments] is in flux.”

Although there are established biomarkers for MM, novel biomarkers are needed for improved disease diagnosis and treatment.¹ The complexity of the disease, along with novel treatment approaches, warrants the exploration of unique biomarkers for improving early diagnosis and optimizing response to treatment, which may lead to improved clinical management of MM and survival outcomes.

Minimal residual disease (MRD) is being assessed in clinical practice and has emerged as a pertinent and potential surrogate biomarker in MM. Patients who achieve MRD-negative status have longer progression-free survival (PFS) and overall survival (OS); therefore, MRD is a useful prognostic tool.²

Thomas G. Martin, MD

“We’re looking at MRD assessment in the marrow, based on sequencing of the immunoglobulin light and heavy chain genes from the malignant plasma cells at diagnosis, which are unique sequences, similar to a fingerprint...[this] serves as a really good predictor of long-term response in myeloma. I’ve been routinely sending MRD assessment on patients [who have just received diagnoses] for several years because the test is now authorized by the FDA,” said Thomas G. Martin, MD, clinical professor of medicine, associate director of the Myeloma Program at University of California San Francisco, and coleader of the Cancer Immunology & Immunotherapy Program at Helen Diller Family Comprehensive Cancer Center, also in San Francisco.

"We’re entering the immunotherapy era for treating relapsed [MM] and these novel drugs, most targeting B-cell maturation antigen (BCMA), are showing impressive early results,” Martin said. The high-specific and tissue-specific expression of BCMA on myeloma cells has quickly advanced this target and propelled the development of novel BCMA-directed therapies in myeloma.⁴ Additional evidence has demonstrated that soluble BCMA (sBCMA) levels may be a useful biomarker for precursor plasma cell disorders including monoclonal gammopathy of undetermined significance and smoldering MM. In a retrospective study, increased levels of sBCMA in the precursor state were associated with disease progression to active MM. Additionally, patients with higher baseline sBCMA levels had poorer PFS and OS outcomes.⁴

Martin added, “The hard part about soluble BCMA is that there’s not a currently available CLIA [Clinical Laboratory Improvement Amendment] test. Studies are evaluating whether sBCMA can accurately predict response to therapy and may be an early marker for recurrence/progression. So far, several studies have shown that when a patient has a great response, the sBCMA levels become undetectable and when sBCMA levels become detectable, it’s a sign that the myeloma is growing back again. We are very hopeful that a CLIA test will be developed and that sBCMA will be an excellent biomarker for [MM].”

Another potential novel biomarker is the presence of the translocation t(11;14) by bone marrow FISH testing.⁵ “The t(11;14) translocation in myeloma is associated with the upregulation of BCL2 pathway, and thus researchers began investigating the clinical use of BCL2 inhibitors in this subset of patients,” said Martin. Patients whose myeloma cells express the t(11;14) translocation have demonstrated clinical responses to venetoclax (Venclexta).

According to Bustoros, “Until now, the only known predictive biomarker for response to therapy in a patient is having t(11;14). We know venetoclax would be a good option for [patients with t(11;14)] at relapse. It’s not [FDA] approved for up-front treatment yet.”

Looking into the future for using t(11;14) as a biomarker for drug therapy, Martin added, “There are trials going on right now using venetoclax in patients with t(11;14) and those patients do extremely well...I suspect [venetoclax] will be approved for use in patients with t(11;14) as part of frontline therapy and in relapse within the next few years.” Other exploratory biomarkers that may be associated with t(11;14) are del(17p) or gain(1q).⁵

Other emerging biomarkers include circulating tumor cells (CTCs) and microRNAs (miRNAs). “[miRNAs] and CTCs are in early investigations in myeloma and we’re still figuring out which assays to use, and how and in which patients these bioassays may help,” said Martin. CTCs were found to be released in the peripheral blood of MM from the tumor cells in bone marrow and detected by flow cytometry.^1,2 The benefit of CTCs is the noninvasive nature of their use for detecting MM compared with a bone marrow biopsy for diagnosis.² Additionally, the use of CTCs may be prognostic at diagnosis and they may be used in conjunction with MRD as a response biomarker.¹

MiRNAs are expressed on all cells and consist of short noncoding RNAs. MiRNAs are an attractive biomarker in MM due to their function as tumor promoters or suppressors. There is potential for the use of miRNAs in the diagnosis and prognosis of MM. However, more research is needed for validation of miRNA use.¹ “Given the difficulties in isolating [miRNAs], detecting them, and measuring them, I would say it needs time to be translated clinically,” said Bustoros.

Other novel biomarkers that may warrant further exploration and evidence for use include proteomic and angiogenesis biomarkers. The use of proteomic biomarkers has the potential to provide diagnostic and prognostic information in patients with MM.² Further research into proteins such as proteasome activator complex subunit 1, heat shock protein 90, and others may provide insight into how these proteins may be used as biomarkers for patients with MM in the future.² Angiogenesis biomarkers are known to be associated with tumor cells requiring adequate blood supply for tumor growth.¹ Markers associated with angiogenesis may include VEGF, hepatocyte growth factor (HGF), angiopoietins, and JUNB.²

“There don’t seem to be [many] mutations that are targetable in myeloma. We do see KRAS, NRAS, and occasional BRAF mutations, so we do see mutations in which there may be drugs that potentially could target these pathways, but there are only a few studies investigating specific mutation-driven treatment in patients with myeloma. We’re really at the infancy compared with other malignancies such as lung cancer,” said Martin.

There may be other genetic or mutationally driven treatment pathways for the future, perhaps ways to predict drug/disease resistance. The immunomodulatory [IMiD] drugs target a protein called cereblon. We’re only starting to learn about mutations in cereblon and that these mutations might predict resistance to the IMiD class of medications. Similarly, we are starting to identify deletions on chromosome 16 that are associated with BCMA loss on plasma cells,” said Martin. The efficacy of IMiDs depends on the presence of cereblon, a binding protein, and the efficacy of BCMA therapeutics depends on the surface expression of BCMA.⁶ Although cereblon is not a biomarker currently used in practice, it is under investigation as a promising potential marker in resistance to IMiDs.⁶

Other potential biomarkers that may provide insight into resistance include del(17p) and gain(1q).⁷

"We know these 2 genetic alterations are biomarkers of worse response to treatment in general,” Bustoros said. Patients harboring high-risk cytogenetics have poor prognosis regardless of treatment options.⁷ Bustoros also said that “[patients with del(17p) and gain(1q)] are the ones who frequently relapse and progress after multiple lines of treatment.”

There are many potential biomarkers on the horizon for patients with MM. Although the impact of research in biomarker assessment may be intangible now, a tangible change to clinical practice was discussed by Martin: For biomarker measurement, “an emerging test that’s going to be really important is mass spectroscopy of the monoclonal protein in the blood. Assessment of serum M protein by mass spectroscopy will be much more sensitive and will be able to detect a far lower level of M protein compared with the current protein electrophoresis and immunofixation electrophoresis assays. M protein quantification by mass spectroscopy may be as sensitive as some of the MRD assays from bone marrow. It’ll be a great technique to use together with bone marrow MRD and a great blood test to identify deep remissions from standard therapy as well as from some of the new novel therapies.”

Progress continues in the research and development of biomarker assessment in MM. The complexity of the disease may warrant multiple biomarkers to provide clarity on diagnosis, prognosis, and response to treatment with the goal of personalizing patient treatment to improve outcomes.

“There are a lot of evolving biomarkers and that will benefit patient treatment...integrating genetic biomarkers with biomarkers that can be measured from blood samples, bone marrow biopsies, and circulating tumor cells,” Bustoros said. “All of this would be used in the future to identify patients who would progress at very early time points. I think biomarkers would be very important to tailor therapy for specific patients...the sequence of treatment also would benefit from understanding the biomarkers and knowing the biomarkers of response.”

_REFERENCES:

<sub>1. Gupta N, Sharma A, Sharma A. Emerging biomarkers in multiple myeloma: A review. Clin Chim Acta. 2020;503:45-53. doi:10.1016/j. cca.2019.12.026
2. Soliman AM, Das S, Teoh SL. Next-generation biomarkers in multiple myeloma: understanding the molecular basis for potential use in diagnosis and prognosis. Int J Mol Sci. 2021;22(14):7470. doi:10.3390/ijms22147470</sub>

_{3. Wallington-Beddoe CT, Mynott RL. Prognostic and predictive biomarker developments in multiple myeloma. . 2021;14(1):151. doi:10.1186/s13045-021-01162-7}

_{4. Visram A, Soof C, Rajkumar SV, et al. Serum BCMA levels predict outcomes in MGUS and smoldering myeloma patients. Blood Cancer J. 2021;11(6):120. doi:10.1038/s41408-021-00505-4}

_{5. Kaufman JL, Gasparetto C, Schjesvold FH, et al. Targeting BCL-2 with venetoclax and dexamethasone in patients with relapsed/refractory t(11;14) multiple myeloma. Am J Hematol. 2021;96(4):418-427. doi:10.1002/ajh.26083}

_{6. Gooding S, Ansari-Pour N, Towfic F, et al. Multiple cereblon genetic changes are associated with acquired resistance to lenalidomide or pomalidomide in multiple myeloma. Blood. 2021;137(2):232-237. doi:10.1182/blood.2020007081}

_{7. Bustoros M, Mouhieddine TH, Detappe A, Ghobrial IM. Established and novel prognostic biomarkers in multiple myeloma. Am Soc Clin Oncol Educ Book. 2017;37:548-560. doi:10.1200/EDBK_175175}