Monocyte-to-platelets ratio (MPR) at diagnosis is associated with inferior progression-free survival in patients with mantle cell lymphoma: a multi-center real-life survey.

Mantle cell lymphoma (MCL) pathogenesis is strongly related to the role of the tumor immune microenvironment (TIME) in which MCL cells proliferate. TIME cells can produce growth signals influencing MCL cells' survival and exert an antitumoral immune response suppression. The activity of TIME cells might be mirrored by some ratios of peripheral blood cell subpopulations, such as the monocyte-to-platelet ratio (MPR). We reviewed the clinical features of 165 consecutive MCL patients newly diagnosed and not eligible for autologous stem cell transplantation (both for age or comorbidities) who accessed two Italian Centers between 2006 and 2020. MPR was calculated using data obtained from the complete blood cell count at diagnosis before any cytotoxic treatment and correlated with PFS. Univariate analysis showed that MPR ≥ 3 was associated with inferior PFS (p = 0.02). Multivariate analysis confirmed that MPR ≥ 3, LDH > 2.5 ULN, and bone marrow involvement were significant independent variables in predicting PFS. For these reasons, MPR ≥ 3 seems the most promising prognostic factor in patients with MCL, and it could be considered a variable in new predictive models.

Dexamethasone treatment for COVID-19 is related to increased mortality in hematologic malignancy patients: results from the EPICOVIDEHA Registry.

Not available.

Baseline IgM Amounts Can Identify Patients with Poor Outcomes: Results from a Real-Life Single-Center Study on Classical Hodgkin Lymphoma.

Hodgkin Lymphoma (HL) is characterized by an inflammatory background in which the reactive myeloid cells may exert an immune-suppressive effect related to the progression of the disease. Immunoglobulin M is the first antibody isotype produced during an immune response, which also plays an immunoregulatory role. Therefore, we investigated if, as a surrogate of defective B cell function, it could have any clinical impact on prognosis. In this retrospective, observational, single-center study, we evaluated 212 newly diagnosed HL patients, including 132 advanced-stage. A 50 mg/dL level of IgM at baseline resulted in 84.1% sensitivity and 45.5% specificity for predicting a complete response in the whole cohort (area under curve (AUC) = 0.62, p = 0.013). In multivariate analysis, baseline IgM ≤ 50 mg/dL and the presence of a large nodal mass (<7 cm) were independent variables able to predict the clinical outcome, while, after two cycles of treatment, IgM ≤ 50 mg/dL at baseline and PET-2 status were independent predictors of PFS. The amount of IgM at diagnosis is a valuable prognostic factor much earlier than PET-2, and it can also provide information for PET-2-negative patients. This can help to identify different HL classes at risk of treatment failure at baseline.

High-dose chemotherapy and autologous stem cell transplant as first salvage treatment for relapsed or refractory Hodgkin Lymphoma in the era of PET-adapted strategies.

Data on the efficacy of high-dose chemotherapy and autologous stem cell transplantation (ASCT) for classical Hodgkin lymphoma (cHL) patients who failed a PET-driven first-line therapy are limited.We retrospectively evaluated 220 adult cHL patients who underwent ASCT from 2009 to 2021 at 11 centers in Italy. Overall, 49.5% had refractory disease, 23.2% relapsed < 12 and 27.3% ≥12 months from the end of first-line chemotherapy. The 3-year progression-free survival (PFS) and overall survival (OS) were 73.8% and 89.4%. In univariable analysis for PFS events PET-2+ (HR 2.69, p = .001), anemia (HR 2.22, p = .019), refractory disease (HR 1.76, p = .045), less than CR before ASCT (HR 3.24, p < .001) and >2 lines of salvage therapy (HR 2.52; p = .004) were associated with a higher risk of failure after ASCT. In multivariable analysis, >2 lines of salvage therapy (HR 3.28, p = .004) and RT before ASCT (HR 3.00, p = 0.041) retained significance.ASCT is an effective salvage approach for cHL patients treated in the era of PET-adapted therapies.

Efficacy and safety of tixagevimab-cilgavimab versus SARS-CoV-2 breakthrough infection in the hematological conditions.

BACKGROUND: Managing SARS-CoV-2 infection in frail and immunosuppressed patients still represents an open challenge, but, starting from the phase 3 PROVENT study, prophylaxis with tixagevimab-cilgavimab has improved the approach in this category of patients, guaranteeing a better outcome and inferior mortality. Real-life data in a heterogeneous cohort are few. METHODS: The aim of this study is to evaluate the benefit of prophylaxis with tixagevimab-cilgavimab in a cohort of 202 patients affected by different hematological diseases (lymphoproliferative, myeloproliferative, autoimmune, patients recently receiving a bone marrow transplant), active (with ongoing treatment), or in watch-and-wait strategy, followed in our center, during a median follow-up of 249 (45-325) days. RESULTS: An incidence of 44 breakthrough infections (21.8%) is reported, with no treatment-related adverse effects. Age ≥70 years, ongoing treatment (above all with monoclonal antibodies), baseline lymphoproliferative disorders, and prior virus exposure are identified as risk factors related to subsequent infection (p < 0.05). Moreover, the incidence is higher in low/nonresponse to prior vaccination (p = .002). Patients treated with tixagevimab-cilgavimab had a mild course of the infection and a reduction of the duration compared with preprophylaxis infection (11 vs. 15 days, p < .001). The concurrent treatment with anti-CD20 monoclonal antibodies and B-non-Hodgkin lymphoma still confers a higher duration of infection despite prophylaxis. No deaths attributable to the infection occurred. CONCLUSION: Prophylaxis treatment seems to be a valid and safe strategy, although not preventing breakthrough infection, but the severe complications associated with the infection and the possible delays in administering lifesaving therapies from long positivity.

Engagement of Mesenchymal Stromal Cells in the Remodeling of the Bone Marrow Microenvironment in Hematological Cancers.

Mesenchymal stromal cells (MSCs) are a subset of heterogeneous, non-hematopoietic fibroblast-like cells which play important roles in tissue repair, inflammation, and immune modulation. MSCs residing in the bone marrow microenvironment (BMME) functionally interact with hematopoietic stem progenitor cells regulating hematopoiesis. However, MSCs have also emerged in recent years as key regulators of the tumor microenvironment. Indeed, they are now considered active players in the pathophysiology of hematologic malignancies rather than passive bystanders in the hematopoietic microenvironment. Once a malignant event occurs, the BMME acquires cellular, molecular, and epigenetic abnormalities affecting tumor growth and progression. In this context, MSC behavior is affected by signals coming from cancer cells. Furthermore, it has been shown that stromal cells themselves play a major role in several hematological malignancies' pathogenesis. This bidirectional crosstalk creates a functional tumor niche unit wherein tumor cells acquire a selective advantage over their normal counterparts and are protected from drug treatment. It is therefore of critical importance to unveil the underlying mechanisms which activate a protumor phenotype of MSCs for defining the unmasked vulnerabilities of hematological cancer cells which could be pharmacologically exploited to disrupt tumor/MSC coupling. The present review focuses on the current knowledge about MSC dysfunction mechanisms in the BMME of hematological cancers, sustaining tumor growth, immune escape, and cancer progression.

Multiple Myeloma in 2023 Ways: From Trials to Real Life.

Multiple myeloma is a chronic hematologic malignancy that obstinately tends to relapse. Basic research has made giant strides in better characterizing the molecular mechanisms of the disease. The results have led to the manufacturing of new, revolutionary drugs which have been widely tested in clinical trials. These drugs have been approved and are now part of the therapeutic armamentarium. As a consequence, it is essential to combine what we know from clinical trials with real-world data in order to improve therapeutic strategies. Starting with this premise, our review aims to describe the currently employed regimens in multiple myeloma and compare clinical trials with real-life experiences. We also intend to put a spotlight on promising therapies such as T-cell engagers and chimeric antigen receptor T-cells (CAR-T) which are proving to be effective in changing the course of advanced-stage disease.

Modeling cell populations metabolism and competition under maximum power constraints.

Ecological interactions are fundamental at the cellular scale, addressing the possibility of a description of cellular systems that uses language and principles of ecology. In this work, we use a minimal ecological approach that encompasses growth, adaptation and survival of cell populations to model cell metabolisms and competition under energetic constraints. As a proof-of-concept, we apply this general formulation to study the dynamics of the onset of a specific blood cancer-called Multiple Myeloma. We show that a minimal model describing antagonist cell populations competing for limited resources, as regulated by microenvironmental factors and internal cellular structures, reproduces patterns of Multiple Myeloma evolution, due to the uncontrolled proliferation of cancerous plasma cells within the bone marrow. The model is characterized by a class of regime shifts to more dissipative states for selectively advantaged malignant plasma cells, reflecting a breakdown of self-regulation in the bone marrow. The transition times obtained from the simulations range from years to decades consistently with clinical observations of survival times of patients. This irreversible dynamical behavior represents a possible description of the incurable nature of myelomas based on the ecological interactions between plasma cells and the microenvironment, embedded in a larger complex system. The use of ATP equivalent energy units in defining stocks and flows is a key to constructing an ecological model which reproduces the onset of myelomas as transitions between states of a system which reflects the energetics of plasma cells. This work provides a basis to construct more complex models representing myelomas, which can be compared with model ecosystems.

Potential clinical impact of T-cell lymphocyte kinetics monitoring in patients with B cell precursors acute lymphoblastic leukemia treated with blinatumomab: a single-center experience.

Blinatumomab is a bispecific anti-CD3 and anti-CD19 antibody that acts as a T-cell engager: by binding CD19+ lymphoblasts, blinatumomab recruits cytotoxic CD3+ T-lymphocytes to target the cancer cells. Here we describe seven different patients affected by B-cell precursor acute lymphoblastic leukemia (Bcp-ALL) and treated with blinatumomab, on which we evaluated the potential association between the amount of different T-cells subsets and deep molecular response after the first cycle, identified as a complete remission in the absence of minimal residual disease (CR/MRD). The immune-system effector cells studied were CD3+, CD4+ effector memory (T4-EM), CD8+ effector memory (T8-EM), and T-regulatory (T-reg) lymphocytes, and myeloid-derived suppressor cells (MDSC). Measurements were performed in the peripheral blood using flow cytometry of the peripheral blood at baseline and after the first cycle of blinatumomab. The first results show that patients with a higher proportion of baseline T-lymphocytes achieved MRD negativity more frequently with no statistically significant difference (p=0.06) and without differences in the subpopulation count following the first treatment. These extremely preliminary data could potentially pave the way for future studies, including larger and less heterogeneous cohorts, in order to assess the T-cell kinetics in a specific set of patients with potential synergy effects in targeting myeloid-derived suppressor cells (MDSC), commonly known to have an immune evasion mechanism in Bcp-ALL.

Gaucher disease prevalence in 600 patients affected by monoclonal gammopathy of undetermined significance.

BACKGROUND: Gaucher disease (GD) is a rare autosomal recessive inherited disorder caused by the lysosomal enzyme acid ß-glucosidase deficiency. Many patients experience a critical delay in the diagnosis of up to 8-10 years due to its rarity and variability in signs and symptoms, with the consultation of several specialists. PATIENTS AND METHODS: This prospective observational study analyzed the prevalence of GD in 600 patients with monoclonal gammopathy of uncertain significance (MGUS) from January 2018 until February 2022. RESULTS: The mean age of participants was 66 years, with a mean monoclonal component of 0.58 g/dL. In 433 MGUS patients with available data, anemia (hemoglobin level < 10 g/dL) was present in 31 patients (7%), and thrombocytopenia (platelet count <100.000/mm3 ) in 24 (5.5%). Of 600 MGUS patients tested for acid ß-glucosidase enzyme activity, 7 patients (1.2%) had activity below 2.5 nmol/h/mL. In comparison, GBA gene analysis was executed in 110 patients. It revealed 4 patients (0.7%) affected by GD (3 patients with compound heterozygous mutation and 1 with homozygous mutation), with a prevalence of 1 every 150 MGUS patients. Furthermore, 12 out of the remaining 106 evaluated patients (11%) were carriers of a single heterozygous mutation while having regular enzyme activity. CONCLUSIONS: The clinical heterogeneity of GD and frequent lack of awareness among physicians often lead to diagnostic delays and severe clinical manifestations. The role of MGUS in the presence of at least one clinical sign, such as low platelet count, organomegaly, bone pain, or bleeding tendency, could aid in initiating GD screening with DBS, thus reducing the period between symptom onset and the diagnosis of this rare disease.

Lenalidomide plus Dexamethasone Combination as First-Line Oral Therapy of Multiple Myeloma Patients: A Unicentric Real-Life Study.

Based on the results obtained in clinical trials, the use of the combination of lenalidomide and dexamethasone (Len/Dex) has become a potential therapeutic choice for newly diagnosed multiple myeloma (NDMM) ineligible for autologous stem cell transplantation. This study evaluated 89 frail NDMM patients treated with first-line oral association. At the last follow-up, 34 out of 89 patients (38.2%) were alive, and 22 were still in treatment with Len/Dex. Among 73 evaluable patients who received at least two cycles, the overall response rate was 71% (N = 52). The disease control rate, defined as any level of clinical response to therapy, occurred in 71 patients (97%). We reported one or more adverse events of grade 3 or 4 (G3/4) in 65.2% (N = 58) of patients, with a prevalence of hematological toxicity (24 patients), leading to an overall discontinuation of treatment in two cases. In univariate analysis, high ISS, high serum ß2-microglobulin, and creatinine clearance <30 mL/min negatively impact OS, while the depth of response positively impacts OS. Moreover, G3-4 anemia, ISS, frailty score, and ECOG negatively impacts PFS. In conclusion, elderly and more frail patients benefit from the Len/Dex combination also in the era of monoclonal antibodies, ensuring an increased PFS and OS in patients where the therapeutic choice is often limited and usually not very effective.

Molnupiravir compared to nirmatrelvir/ritonavir for COVID-19 in high-risk patients with haematological malignancy in Europe. A matched-paired analysis from the EPICOVIDEHA registry.

INTRODUCTION: Molnupiravir and nirmatrelvir/ritonavir are antivirals used to prevent progression to severe SARS-CoV-2 infections and decrease hospitalisation and mortality rates. Nirmatrelvir/ritonavir was authorised in Europe in December 2021, whereas molnupiravir is not yet licensed in Europe as of February 2022. Molnupiravir may be an alternative to nirmatrelvir/ritonavir because it is associated with fewer drug-drug interactions and contraindications. A caveat for molnupiravir is the mode of action induces viral mutations. Mortality rate reduction with molnupiravir was less pronounced than that with nirmatrelvir/ritonavir in patients without haematological malignancy. Little is known about the comparative efficacy of the two drugs in patients with haematological malignancy at high-risk of severe COVID-19. Thus, molnupiravir and nirmatrelvir/ritonavir were compared in a cohort of patients with haematological malignancies. METHODS: Clinical data from patients treated with molnupiravir or nirmatrelvir/ritonavir monotherapy for COVID-19 were retrieved from the EPICOVIDEHA registry. Patients treated with molnupiravir were matched by sex, age (±10 years), and severity of baseline haematological malignancy to controls treated with nirmatrelvir/ritonavir. RESULTS: A total of 116 patients receiving molnupiravir for the clinical management of COVID-19 were matched to an equal number of controls receiving nirmatrelvir/ritonavir. In each of the groups, 68 (59%) patients were male; with a median age of 64 years (interquartile range [IQR] 53-74) for molnupiravir recipients and 64 years (IQR 54-73) for nirmatrelvir/ritonavir recipients; 56.9% (n=66) of the patients had controlled baseline haematological malignancy, 12.9% (n=15) had stable disease, and 30.2% (n=35) had active disease at COVID-19 onset in each group. During COVID-19 infection, one third of patients from each group were admitted to hospital. Although a similar proportion of patients in the two groups were vaccinated (molnupiravir n=77, 66% vs. nirmatrelvir/ritonavir n=87, 75%), more of those treated with nirmatrelvir/ritonavir had received four vaccine doses (n=27, 23%) compared with those treated with molnupiravir (n=5, 4%) (P<0.001). No differences were detected in COVID-19 severity (P=0.39) or hospitalisation (P=1.0). No statistically significant differences were identified in overall mortality rate (P=0.78) or survival probability (d30 P=0.19, d60 P=0.67, d90 P=0.68, last day of follow up P=0.68). Deaths were either attributed to COVID-19, or the infection was judged by the treating physician to have contributed to death. CONCLUSIONS: Hospitalisation and mortality rates with molnupiravir were comparable to those with nirmatrelvir/ritonavir in high-risk patients with haematological malignancies and COVID-19. Molnupiravir is a plausible alternative to nirmatrelvir/ritonavir for COVID-19 treatment in patients with haematological malignancy.

Pars Plana Vitrectomy Alone or Combined with Phacoemulsification to Treat Rhegmatogenous Retinal Detachment: A Systematic Review of the Recent Literature.

Pars plana vitrectomy is today a common first-line procedure for treatment of rhegmatogenous retinal detachment (RRD). Removal or preservation of the natural lens at the time of vitrectomy is associated with both advantages and disadvantages. The combination of cataract extraction (i.e., phacoemulsification) with pars plana vitrectomy (PPVc) enhances visualization of the peripheral retina and the surgical management of the vitreous base. However, PPVc prolongs the surgical time and is associated with iatrogenic loss of the accommodation function in younger patients, possible postoperative anisometropia, and unexpected refractive results. Performance of pars plana vitrectomy alone (PPVa) requires good technical skills to minimize the risk of lens damage, and quickens cataract development. We retrieved all recent papers that directly compared PPVc and PPVa using parameters that we consider essential when choosing between the two procedures (the success rate of anatomical RRD repair, postoperative refractive error, intra- and postoperative complications, and costs). PPVa and PPVc were generally comparable in terms of RRD anatomical repair. PPVc was associated with fewer intraoperative, but more postoperative, complications. Macula-off RRD PPVc treatment was often associated with undesirable myopic refractive error. PPVa followed by phacoemulsification was the most expensive procedure.

A case of high-risk AML in a patient with advanced systemic mastocytosis.

Aggressive SM + AML has limited therapeutic options. Even a strong combination of decitabine-venetoclax-midostaurin has a transient effect on AML and a mitigated effect on SM. Larger series are required to identify the best therapeutic strategy.

Clinical outcome of SARS-CoV-2 infections occurring in multiple myeloma patients after vaccination and prophylaxis with tixagevimab/cilgavimab.

Introduction: Patients with multiple myeloma (MM) frequently reported immune impairment with an increased risk for infection-related mortality. We aimed to evaluate the immune response in MM patients vaccinated for SARS-CoV-2 during active treatment. Methods: We enrolled 158 patients affected by active MM or smoldering MM (SMM) and 40 healthy subjects. All subjects received 2 or 3 doses of the BNT162b2 (Pfizer/BioNTech) vaccine, and the anti-spike IgG values were evaluated after every dose. We applied the Propensity Score Matching (PSM) as a consequence of the limited sample size and its heterogeneity to adjust for differences in baseline clinical variables between MM patients who achieved or not a vaccine response after 2 or 3 doses. Results: At 30 days from the second dose, the median antibodies level in MM was 25.2 AU/mL, lower than in SMM and in the control group. The same results were confirmed after the third dose, with lower median anti-spike IgG levels in MM, compared to SMM and control group. Following PSM, lack of response to SARS-CoV-2 complete vaccination plus boost was associated with age more than 70 years old and use of high-dose of steroids. We failed to identify an association between specific treatment types and reduced vaccine response. The use of prophylaxis with tixagevimab/cilgavimab for 40 non-responder patients after 3 doses of vaccine has proven to be an effective and safe approach in reducing the risk of serious illness in the event of a breakthrough SARS-CoV-2 infection, faced with a mild symptomatic course, and in providing protection instead of long-term humoral immune vaccine responses. Following PSM, only the high-risk cytogenetic abnormalities were associated with an increased risk of developing a breakthrough SARS-CoV-2 infection. Conclusion: Monitoring the immune response is fundamental in MM patients that remain highly vulnerable to SARS-CoV-2 despite the vaccine. The use of prophylaxis with tixagevimab/cilgavimab can guarantee better protection from the severe form of the disease.

Multicentric Castleman Disease and Concurrent Hematological Disorders: The Occurrence of Plasmacytoma and the Hypotheses Arising from Literature Review.

The concomitant presence of Castleman disease (CD) with other hematological pathology is an event described in the literature with increasing frequency, able to modify the diagnostic and curative approach in such patients. Very few studies in the literature describe the association of CD with concomitant neoplastic diseases; the most frequent are Kaposi's sarcomas (especially in HIV and human herpes virus-8-positive patients) and lymphoproliferative disorders, such as lymphomas. Instead, since the association with plasma cell diseases such as multiple myeloma and plasmacytoma is infrequent, there is a lack of literature. This manuscript aimed to revise the literature by describing a rare case of CD and plasmacytoma and attempting to explain the underlying triggering mechanisms.

Ruxolitinib treatment in myelofibrosis and polycythemia vera causes suboptimal humoral immune response following standard and booster vaccination with BNT162b2 mRNA COVID-19 vaccine.

Patients affected by myelofibrosis (MF) or polycythemia vera (PV) and treated with ruxolitinib are at high risk for severe coronavirus disease 2019. Now a vaccine against the virus SARS-CoV-2, which is responsible for this disease, is available. However, sensitivity to vaccines is usually lower in these patients. Moreover, fragile patients were not included in large trials investigating the efficacy of vaccines. Thus, little is known about the efficacy of this approach in this group of patients. In this prospective single-center study, we evaluated 43 patients (30 MF patients and 13 with PV) receiving ruxolitinib as a treatment for their myeloproliferative disease. We measured anti-spike and anti-nucleocapsid IgG against SARS-CoV2 15-30 days after the second and the third BNT162b2 mRNA vaccine booster dose. Patients receiving ruxolitinib showed an impaired antibody response to complete vaccination (2 doses), as 32.5% of patients did not develop any response. After the third booster dose with Comirnaty, results slightly improved, as 80% of these patients produced antibodies above the threshold positivity. However, the quantity of produced antibodies was well below that reached than those reported for healthy individuals. PV patients elicited a better response than patients affected by MF. Thus, different strategies should be considered for this high-risk group of patients.

Mesenchymal stromal cells in tumor microenvironment remodeling of BCR-ABL negative myeloproliferative diseases.

Chronic myeloproliferative neoplasms encompass the BCR-ABL1-negative neoplasms polycythemia vera (PV), essential thrombocythemia (ET), and primary myelofibrosis (PMF). These are characterized by calreticulin (CALR), myeloproliferative leukemia virus proto-oncogene (MPL) and the tyrosine kinase Janus kinase 2 (JAK2) mutations, eventually establishing a hyperinflammatory tumor microenvironment (TME). Several reports have come to describe how constitutive activation of JAK-STAT and NFκB signaling pathways lead to uncontrolled myeloproliferation and pro-inflammatory cytokines secretion. In such a highly oxidative TME, the balance between Hematopoietic Stem Cells (HSCs) and Mesenchymal Stromal Cells (MSCs) has a crucial role in MPN development. For this reason, we sought to review the current literature concerning the interplay between HSCs and MSCs. The latter have been reported to play an outstanding role in establishing of the typical bone marrow (BM) fibrotic TME as a consequence of the upregulation of different fibrosis-associated genes including PDGF- ß upon their exposure to the hyperoxidative TME characterizing MPNs. Therefore, MSCs might turn to be valuable candidates for niche-targeted targeting the synthesis of cytokines and oxidative stress in association with drugs eradicating the hematopoietic clone.

Myelofibrosis and Survival Prognostic Models: A Journey between Past and Future.

Among the myeloproliferative diseases, myelofibrosis is a widely heterogeneous entity characterized by a highly variable prognosis. In this context, several prognostic models have been proposed to categorize these patients appropriately. Identifying who deserves more invasive treatments, such as bone marrow transplantation, is a critical clinical need. Age, complete blood count (above all, hemoglobin value), constitutional symptoms, driver mutations, and blast cells have always represented the milestones of the leading models still used worldwide (IPSS, DIPSS, MYSEC-PM). Recently, the advent of new diagnostic techniques (among all, next-generation sequencing) and the extensive use of JAK inhibitor drugs have allowed the development and validation of new models (MIPSS-70 and version 2.0, GIPSS, RR6), which are continuously updated. Finally, the new frontier of artificial intelligence promises to build models capable of drawing an overall survival perspective for each patient. This review aims to collect and summarize the existing standard prognostic models in myelofibrosis and examine the setting where each of these finds its best application.

Lactate trafficking inhibition restores sensitivity to proteasome inhibitors and orchestrates immuno-microenvironment in multiple myeloma.

Metabolic changes of malignant plasma cells (PCs) and adaptation to tumour microenvironment represent one of the hallmarks of multiple myeloma (MM). We previously showed that MM mesenchymal stromal cells are more glycolytic and produce more lactate than healthy counterpart. Hence, we aimed to explore the impact of high lactate concentration on metabolism of tumour PCs and its impact on the efficacy of proteasome inhibitors (PIs). Lactate concentration was performed by colorimetric assay on MM patient's sera. The metabolism of MM cell treated with lactate was assessed by seahorse and real time Polymerase Chain Reaction (PCR). Cytometry was used to evaluate mitochondrial reactive oxygen species (mROS), apoptosis and mitochondrial depolarization. Lactate concentration resulted increased in MM patient's sera. Therefore, PCs were treated with lactate and we observed an increase of oxidative phosphorylation-related genes, mROS and oxygen consumption rate. Lactate supplementation exhibited a significant reduction in cell proliferation and less responsive to PIs. These data were confirmed by pharmacological inhibition of monocarboxylate transporter 1 (MCT1) by AZD3965 which was able to overcame metabolic protective effect of lactate against PIs. Consistently, high levels of circulating lactate caused expansion of Treg and monocytic myeloid derived suppressor cells and such effect was significantly reduced by AZD3965. Overall, these findings showed that targeting lactate trafficking in TME inhibits metabolic rewiring of tumour PCs, lactate-dependent immune evasion and thus improving therapy efficacy.