Multiple myeloma (MM), the second most prevalent hematological malignancy, presents a complex clinical landscape marked by the aberrant proliferation of plasma cells and the production of dysfunctional monoclonal proteins (1). This disease predominantly afflicts older adults, with the average age of onset at 70 years, and is propelled by an array of chromosomal aberrations and genetic mutations that culminate in the expansion of a malignant plasma cell clone (2, 3). The insidious onset of MM, often heralded by nonspecific symptoms such as weakness, weight loss, and bone pain, can delay diagnosis until the emergence of more severe complications like disseminated bone lesions, pathological fractures, bone marrow failure, and renal damage, which are an indication for treatment (4, 5).

Newly diagnosed MM patients (NDMM) considered fit (aged <70 years, without comorbidities) are recommended to receive induction followed by high-dose therapy (HDT) with autologous hematopoietic stem cell transplantation (auto-HSCT) and lenalidomide maintenance (6). The induction treatment is usually based on the bortezomib and dexamethasone (Vd) backbone. The updated 2021 European Hematology Association (EHA) and European Society for Medical Oncology (ESMO) clinical practice guidelines recommend the use of either daratumumab-thalidomide-Vd (Dara-VTd) or lenalidomide-Vd (VRd) as first-line options (7).

Elderly patients or patients with NDMM who are not eligible for auto-HSCT should receive VRd (bortezomib, lenalidomide, dexamethasone), DaraVMP (Daratumumab, bortezomib, melphalan, dexamethasone) and DaraRd (Daratumumab, lenalidomide, dexamethasone) (7, 8).

While advancements in treatment, including the use of proteasome inhibitors, immunomodulatory drugs, and monoclonal antibodies, have significantly improved survival outcomes, with a median survival rate that now exceeds six years, with some subsets of patients surviving more than eight years, MM remains incurable (9–12). However, introducing innovative MM treatment, better diagnostics, and improved medical care make the expected OS of patients diagnosed today almost impossible to assess. The newest developments in antibody-drug conjugates, bi-specific antibodies, or chimeric antigen receptor T-cell therapy (CAR-T) cell therapies change the prognosis entirely, even for patients with relapsed and refractory MM (RRMM) (13).

As the therapeutic arsenal against MM expands, so does the imperative to manage treatment-related toxicities, which can range from hematological and gastrointestinal effects to cardiotoxicity and neuropathies (14–16). These toxicities not only compromise patient quality of life but can also necessitate dose reductions, potentially diminishing the efficacy of the therapeutic regimen (17). However, some patients are more prone to selected toxicities (18). The reason for that is often unknown. The ability to find such patients even before starting the therapy could influence the therapy choice, thus significantly improving its outcomes and safety.

Within the intricate milieu of the MM microenvironment, soluble mediators such as cytokines assume pivotal roles in orchestrating immune responses that are fundamental to both the pathology of the disease and the patient’s response to chemotherapy.

Our study is motivated by the pivotal role that cytokines within the MM microenvironment play in tumor growth, angiogenesis, and the immune response (19, 20). The cytokines of interest in this study—IL-6, IL-8, MCP-1, and VEGF—have been selected for their prominence in the MM microenvironment and their documented influence on disease progression and response to treatment, as well as their less understood roles in mediating chemotherapy-induced toxicity.

IL-6, a cytokine with both pro- and anti-inflammatory actions, has been implicated in the pathogenesis of MM, with elevated levels noted in many patients (20–22). It acts as a growth factor for myeloma cells, and its influence on angiogenesis suggests a role in disease advancement. Similarly, IL-8, a pro-inflammatory chemokine, is involved in angiogenesis and may contribute to MM progression and metastasis (19, 23–26). Its regulatory effect on myelopoiesis also presents a potential mechanism through which it could influence treatment responses (27, 28).

VEGF, a key mediator of angiogenesis, has been associated with more aggressive MM variants and may also modulate responses to novel anti-MM agents with antiangiogenic properties (29–31).

Lastly, MCP-1’s role as a chemoattractant and its involvement in angiogenesis and osteoclastogenesis suggest it may be pivotal in MM pathophysiology and associated bone disease (32–34).

Our research addresses the critical need to understand how these soluble factors can be leveraged to predict and potentially mitigate the toxicities associated with MM treatment. By situating these cytokines within the context of immune cell recruitment, activation, and inflammation resolution. Incorporating our previous research findings (35), this study utilizes a multiplex cytometric bead assay to investigate pretreatment serum levels of these cytokines as potential predictors of chemotherapy-induced toxicity. By exploring these associations in a cohort of 81 newly diagnosed MM patients, we aim to contribute to the personalization of treatment modalities, potentially improving therapeutic outcomes and patient well-being.

The tumor microenvironment (TME) in (MM) is intricately shaped by cytokines and soluble mediators, which play crucial roles in its dynamics. Our study highlights the significant prognostic and predictive value of cytokines such as IL-6, IL-8, and VEGF, underscoring their potential as biomarkers for chemotherapy toxicity and their influence on TME reprogramming.

We discovered a notable lack of research on the predictive value of pretreatment cytokine levels for chemotherapy-induced toxicity in MM in the available databases (MEDLINE and Cochrane). Thus, we aimed to address this knowledge gap.

In our study, elevated IL-8 levels were linked to a nearly 4.5-fold increase in infection risk, establishing it as an independent predictor of infection. The role of IL-8 in systemic inflammatory responses remains little understood (50–52). It is known to play key roles in neutrophil chemotaxis, lysosomal enzyme release, adhesion molecule upregulation, intracellular calcium increase, and oxidative burst initiation (53, 54). We did not identify studies specifically evaluating pretreatment IL-8 levels and their association with infection rates during CTH for MM. Wu et al. demonstrated the clinical utility of IL-8, alongside interleukin-2 receptor (IL-2R), in identifying febrile infections in patients with hematologic malignancies (55). This is consistent with van de Geer et al., who also underscored the diagnostic importance of IL-8 in similar settings (56). Additionally, Angel et al. proposed that IL-8 levels at the onset of fever might indicate serious complications like bacteremia, aiding in the early identification of patients needing immediate intensive care (57). These insights are particularly relevant for MM, where infections remain a primary cause of mortality in the early stages post-diagnosis (58, 59). Thus, the predictive application of IL-8 levels could enhance patient monitoring, potentially leading to swifter therapeutic interventions.

Our study offers new insights, showing that lower pre-treatment IL-8 levels significantly correlate with treatment-induced lymphopenia. Interestingly, IL-8 demonstrated specificity and sensitivity as a marker in our multivariate analysis. This contrasts with findings by Chung et al., where elevated IL-8 levels were observed in patients with septic shock and severe lymphopenia (60). The discrepancy likely stems from the inflammatory milieu associated with sepsis, which acutely increases IL-8, a pro-inflammatory cytokine, unlike the stable pre-chemotherapy conditions of our MM patient cohort.

Our study highlighted complex relationships where increased IL-8 levels prior to treatment were linked to a lower risk of lymphopenia but a higher occurrence of infectious complications. This underscores the intricate dynamics between IL-8 concentrations and treatment outcomes. Importantly, serum chemokine and cytokine levels may not fully capture the inflammatory response, as these mediators often operate locally through autocrine signaling. The complexity of the inflammatory response, influenced by a wide range of pathogens, including viruses, bacteria, and fungi, further complicates our findings. Our analysis did not consider the specific etiology of the infections, a factor that could have enriched our understanding of the observed phenomena. Our study demonstrated a significant positive correlation between IL-8 levels and anemia severity during chemotherapy. Reports suggest that IL-8 can inhibit myelopoiesis by suppressing the proliferation of bone marrow progenitor cells through signaling inhibition via its receptor ligand (28). This mechanism highlights the complex role of IL-8 in inflammatory responses and in the regulation of hematopoiesis.

While there is limited research directly linking pretreatment IL-8 levels to anemia during chemotherapy, previous studies have shown a connection between high IL-8 levels and severe aplastic anemia, marked by bone marrow failure (61, 62). Moreover, our analysis identified high VEGF levels as a potential risk factor, with elevated concentrations conferring a roughly fourfold increased risk of developing anemia. This aligns with studies suggesting anemia-induced hypoxia may trigger VEGF secretion, fostering angiogenesis as an adaptive response (63, 64). Considering the elevated VEGF levels observed in more advanced MM cases (30), it is plausible to speculate a correlation where a greater tumor burden could exacerbate bone marrow suppression, thus impeding hemoglobin synthesis during treatment.

Our findings highlight that high IL-8 levels in patients experiencing chemotherapy-induced polyneuropathy correlate with nearly a fourfold increase in risk. Considering polyneuropathy’s common occurrence, especially in patients treated with bortezomib or thalidomide for MM (65), the prognostic value of IL-8 could be pivotal. Our data suggest IL-8’s potential as a biomarker to identify patients at heightened risk of neurotoxicity, offering a pathway toward more personalized treatment strategies.

IL-8 can be produced by various cell types involved in inflammation, including monocytes and endothelial cells. Activation of these cells occurs upon binding with IL-8 receptors, CXCR1 and CXCR2, which are expressed on neutrophils, monocytes, endothelial cells, astrocytes, and microglia (66). IL-8 may significantly influence inflammatory cell mediation in acute and chronic inflammation phases (67).

Studies have linked elevated pro-inflammatory cytokines, including IL-8, to neuropathy in patients with conditions like POEMS syndrome related to osteosclerotic myeloma and neuropathy (68).

Moreover, our findings reveal that lower pre-chemotherapy serum VEGF levels are significantly associated with the onset of treatment-induced neutropenia, indicating a predictive role for VEGF. Further validation of this biomarker could lead to preemptive adjustments in treatment strategies for cancer patients. Neutropenia is a significant challenge in clinical oncology, greatly increasing the risk of severe infections that may necessitate hospitalization, intensive antibiotic treatments, and potentially disrupt crucial chemotherapy regimens (69–73). The economic burden is also notable, as neutropenia-associated hospitalization costs exceeded $2 billion in the U.S. by 2012 (74).

To date, the correlation between MCP-1 levels at diagnosis and subsequent treatment-related toxicities remains uncharted, presenting a novel focus for our pilot study. Valković et al. previously established a link between elevated MCP-1 levels and the primary clinical manifestations of MM, finding that patients with increased pretreatment MCP-1 concentrations experienced heightened severity of bone disease, renal dysfunction, and anemia (75). They posited that this correlation could be partly attributed to reduced renal clearance of MCP-1 due to renal insufficiency, warranting a cautious interpretation of these findings.

Contrary to these associations, our investigation did not observe a statistically significant role for MCP-1 concerning treatment toxicities in MM patients. This could indicate that the influence of MCP-1 may be more nuanced or that our study’s scale was insufficient to detect such associations.

While our study did not focus on the toxicity profiles of individual CTH regimens, our group’s toxicity profile aligns well with findings from previous research. For example, the MRC Myeloma IX trial, which evaluated the CTD regimen for newly diagnosed multiple myeloma (NDMM) patients, reported similar rates of cytopenia (15.5%), sensory neuropathy (23.7%), motor neuropathy (11.7%), constipation (41%), and infection (32.1%) to those observed in our study (76).

CASSIOPEIA study (Bortezomib, thalidomide, and dexamethasone with or without daratumumab before and after autologous stem-cell transplantation for NDMM) used VTD chemotherapy regimen as a control arm (77). Detailed safety analysis showed higher levels of peripheral sensory neuropathy (63%) than in our study (39%). This difference might stem from the greater neurotoxicity of the VTD regimen, which was administered to only 17% of our patients. On the other hand, the study reported comparable levels of hematological toxicities that were observed in our cohort. The meta-analysis of VCD vs. VTD-based regimens as induction therapies in NDMM patients eligible for transplantation showed that peripheral neuropathy grade 3 or higher was 6%, which directly aligned with the results of our study (78).

The cohort size, while aligned with global median age, gender distribution, and disease type for MM, was relatively small, limiting the generalizability of our results. Our selection criteria aimed to create a homogeneous patient group to minimize confounding variables, excluding patients with autoimmune diseases due to their distinct cytokine profiles. This selective demographic may limit the applicability of our findings to a broader MM population. Our methodology focused primarily on the diagnostic performance of cytokine levels using standard statistical tools like ROC analysis. This analysis did not incorporate functional assessments of cytokines, which could provide deeper insights into their roles in MM pathogenesis. Moreover, it did not consider changes in cytokine levels over time or in response to treatment, which are important dynamics that could affect their diagnostic value.

Another limitation is our exclusive focus on serum cytokine levels, neglecting the potential insights that could be gained from analyzing bone marrow samples.

Additionally, our study did not measure cytokine levels in patients actively undergoing chemotherapy, nor did it consider the timing of these measurements in relation to subsequent toxicity assessments. The diversity of chemotherapy regimens within our study cohort, while reflective of real-world clinical settings, resulted in subgroups that were too small to determine statistical significance regarding the impact of treatment choice on cytokine levels and toxicity risks. Furthermore, we collected extensive data on comorbidities and concurrent medications but chose not to include these in our primary analysis. This decision was based on preliminary findings suggesting minimal impact of these variables.

Despite these limitations, our research provides important insights into the predictive value of cytokine concentrations for managing chemotherapy-induced toxicities in MM, paving the way for future studies aimed at refining predictive models for treatment complications and ultimately enhancing the development of personalized treatment approaches (79, 80).

Our research presents compelling evidence that assessing cytokine concentrations, specifically IL-8 and VEGF, can be useful in predicting hematological complications such as lymphopenia, neutropenia, anemia, infection, and polyneuropathy in MM patients.

The potential of these cytokines to predict chemotherapy toxicity, while promising, should be approached with prudence.

This need for cautious optimism underscores the preliminary nature of our results and the imperative for additional studies. A larger, more diverse patient population would enable a more robust analysis, affirming or refuting the capacity of these cytokines as reliable predictive biomarkers in MM therapy.

In summary, while our study contributes to the evolving narrative of cytokine profiles in MM and their association with treatment response, it also highlights the complexity of translating these findings into clinical practice. By deepening our understanding and continuing to investigate these potential biomarkers, we move closer to realizing the promise of personalized medicine in MM treatment, where every patient’s therapeutic pathway is tailored to their unique cytokine landscape.

The raw data supporting the conclusions of this article will be made available by the authors, without undue reservation.

Each patient gave written informed consent for the study. The Committee of Ethics and Research approved the study design at the Medical University of Lublin (consent no.: KE-0254/26/2015 with its actualization KE-0254/77/2019).

MM: Conceptualization, Formal Analysis, Investigation, Methodology, Writing – original draft, Writing – review & editing, Validation. MP-M: Investigation, Methodology, Validation, Writing – original draft, Writing – review & editing. AS-S: Conceptualization, Data curation, Formal Analysis, Funding acquisition, Investigation, Methodology, Project administration, Resources, Supervision, Validation, Writing – original draft, Writing – review & editing. IH-M: Data curation, Formal Analysis, Methodology, Software, Validation, Visualization, Writing – original draft, Writing – review & editing. RM: Data curation, Formal Analysis, Methodology, Software, Validation, Visualization, Writing – original draft, Writing – review & editing. AG: Data curation, Software, Writing – original draft. MH: Funding acquisition, Investigation, Resources, Supervision, Validation, Writing – review & editing.