HLA variations in patients with diffuse large B-cell lymphoma and association with disease risk and prognosis: a case-control study.

Introduction: Human leukocyte antigen (HLA) polymorphisms have been associated with the development of various autoimmune diseases, as well as malignant neoplasms. Non-Hodgkin lymphomas (NHLs) are a heterogenous group of lymphoid malignancies in which a genetic substrate has been established and is deemed to play a crucial role in disease pathogenesis. This study aimed to identify whether variations in the HLA gene region were associated with diffuse large B-cell lymphoma (DLBCL) risk and prognosis. Methods: We defined HLA class I (HLA-A, HLA-B, HLA-C) and class II (HLA-DRB1, HLA-DQB1) alleles in 60 patients with DLBCL and compared the results to those found by 236 healthy adult donors from the bone marrow bank of Northern Greece. HLA typing was performed by two molecular methods, Sequence - Specific Oligonucleotide HLA typing (SSO) and Sequence - Specific Primer HLA typing (SSP), from white blood cells recovered from peripheral blood. The phenotypic frequencies of HLA-A, HLA-B, HLA-C, HLA-DRB1 and HLA-DQB1 between patients and controls were compared with the 2-sided Fisher's exact test. Results with p-value <0.05 were considered statistically significant. Odds Ratios with 95% Confidence Intervals were calculated to further strengthen the results. The 2-sided Fisher's exact test was also applied to alleles found only in one of the two groups, while the odds ratios together with the confidence intervals were corrected with Haldane-Anscombe method. Results: Among the studied HLA polymorphisms, the frequency HLA-C*12 allele was significantly lower in patients with DLBCL compared with control subjects (6.7% vs. 34.7%, OR = 0.16, 95% CI: 0.04-0.44). Frequency of HLA-B*39 was significantly lower in patients with DLBCL compared with controls, but due to the low frequency of this polymorphism in the studied population and small sample size, determinations regarding the significance of this findings were limited. Survival analysis revealed that the presence of HLA-C*12 was not associated with improved or worsened overall and progression-free survival. No statistically significant associations were observed in the phenotypic frequencies of HLA-A, HLA-DQB1, HLA-DRB1 and the rest of HLA-B alleles between the control and DLBCL groups. Discussion: Collectively, our results provide valuable insight regarding the role of HLA variations on DLBCL risk. Further studies are required to consolidate our findings and ascertain the clinical implications of these genetic variations on DLBCL management and prognosis.

Efficacy and safety of daratumumab with ixazomib and dexamethasone in lenalidomide-exposed patients after one prior line of therapy: Final results of the phase 2 study DARIA.

The use of lenalidomide in frontline therapy for patients with newly diagnosed multiple myeloma (MM) has increased the number of those who become refractory to lenalidomide at second line. In this context, we assessed the efficacy of daratumumab in combination with ixazomib and dexamethasone (Dara-Ixa-dex) in the prospective phase 2 study DARIA. Eligible patients had relapsed/refractory MM (RRMM) after one prior line with a lenalidomide-based regimen. The primary endpoint was overall response rate (ORR). Secondary endpoints included survival outcomes, safety and changes in biomarkers of bone metabolism. Overall, 50 patients were enrolled (median age 69 years, 56% males). 32 (64%) patients were refractory to lenalidomide, and 17 (34%) had undergone autologous transplant. The ORR was 64% (n = 32); whereas 17 (34%) had a very good partial response or better. The median time to first response was 1.0 month. After a median follow-up of 23.4 months, the median PFS and OS were 8.1 and 39.2 months, respectively. Furthermore, significant changes in markers of bone metabolism became evident as early as at 6 months on treatment. Regarding safety, 21 (42%) patients had ≥1 grade 3/4 adverse event (AE); the most common was thrombocytopenia (n = 9, 18%). 14 (28%) patients had ≥1 serious AE (SAE), the most common being acute kidney injury and pneumonia (n = 2, each). Four patients died due to infections. In conclusion, second-line treatment with Dara-Ixa-dex in patients with RRMM pre-treated with a lenalidomide-based regimen resulted in rapid responses along with a favorable effect on bone metabolism.

Improved survival of patients with primary plasma cell leukemia with VRd or daratumumab-based quadruplets: A multicenter study by the Greek myeloma study group.

We evaluated the efficacy and prognostic impact of bortezomib-lenalidomide triplet (VRd) or daratumumab-based quadruplets (DBQ) versus previous anti-myeloma therapies, that is, bortezomib standard combinations (BSC) or conventional chemotherapy (CT), in a large cohort of patients with primary plasma cell leukemia (pPCL), including those fulfilling the revised diagnostic criteria, that is, circulating plasma cells (cPCS): ≥5%; 110 pPCL patients (M/F: 51/59; median age 65 years, range: 44-86) out of 3324 myeloma patients (3%), registered in our database between 2001 and 2021, were studied; 37% had cPCS 5%-19%; 89% received novel combinations including DBQ (21%), VRd (16%) and BSC (52%); 35% underwent autologous stem cell transplantation. 83% achieved objective responses. Treatment with VRd/DBQ strongly correlated with a higher complete response rate (41% vs. 17%; p = .008). After a median follow-up of 51 months (95% CI: 45-56), 67 patients died. Early mortality was 3.5%. Progression-free survival was 16 months (95% CI: 12-19.8), significantly longer in patients treated with VRd/DBQ versus BSC/CT (25 months, 95% CI: 13.5-36.5 vs. 13 months 95% CI: 9-16.8; p = .03). Median overall survival (OS) was 29 months (95% CI: 19.6-38.3), significantly longer in patients treated with VRd/DBQ versus BSC/CT (not reached vs. 20 months, 95% CI: 14-26; 3-year OS: 70% vs. 32%, respectively; p < .001; HzR: 3.88). In the multivariate analysis VRd/DBQ therapy, del17p(+) and PLT <100.000/µL, independently predicted OS (p < .05). Our study has demonstrated that in the real-world setting, treatment with VRd/DBQ induces deep and durable responses and is a strong prognostic factor for OS representing currently the best therapeutic option for pPCL.

Genetic and Functional Evidence of Complement Dysregulation in Multiple Myeloma Patients with Carfilzomib-Induced Thrombotic Microangiopathy Compared to Controls.

BACKGROUND: Carfilzomib, an irreversible proteasome inhibitor approved for the treatment of relapsed/refractory Multiple Myeloma (MM) has been associated with Thrombotic Microangiopathy (TMA). Several pathogenetic mechanisms of carfilzomib-induced TMA have been proposed; however, recently, there has been a shift of focus on the potential contribution of complement dysregulation. Our aim was to explore whether patients with carfilzomib-induced TMA harbor germline variants of complement-related genes, which have been characterized as risk factors for TMA. METHODS: We retrospectively recruited consecutive MM patients with carfilzomib-induced TMA and compared them to MM patients who received ≥4 cycles of carfilzomib and did not develop signs/symptoms of TMA, in a 1:2 ratio. Genomic DNA from peripheral blood was analyzed using next generation sequencing (NGS) with a complement-related gene panel; ADAMTS13 activity and soluble C5b-9 were measured using ELISA. RESULTS: Complement-related variants were more common in patients with carfilzomib-induced TMA compared to non-TMA controls, regardless of patient and treatment characteristics; ADAMTS13 activity and C5b-9 were compatible with the phenotype of complement-related TMA. CONCLUSIONS: We confirmed the previous findings that implicated complement-related genes in the pathogenesis of carfilzomib-induced TMA. Most importantly, by incorporating a control group of non-TMA MM patients treated with carfilzomib-based regimens and functional complement assays, we enhanced the credibility of our findings.

Daratumumab Improves Bone Turnover in Relapsed/Refractory Multiple Myeloma; Phase 2 Study "REBUILD".

Biomarkers of bone turnover in serum are suggestive of bone dynamics during treatment in multiple myeloma (MM). We evaluated the role of daratumumab on bone remodeling among patients with relapsed/refractory MM in the prospective, open-label, phase 2 study REBUILD. Daratumumab was administered according to the approved indication. A total of 33 out of 57 enrolled patients completed 4 months of treatment. The median percent change from baseline to 4 months in C-terminal cross-linking telopeptide of type 1 collagen (CTX) (primary endpoint) was 3.9%, with 13 (39.4%) and 11 (33.3%) patients showing at least 20% and 30% reduction in CTX levels, respectively. The median percent decrease from baseline to 4 months in tartrate resistant acid phosphatase 5b (TRACP-5b) levels (co-primary endpoint) was 2.6%, with 10 (30.3%) and 6 (18.2%) patients showing at least 20% and 30% reduction in TRACP-5b levels, respectively. However, the changes in these markers of bone catabolism were not statistically significant. Furthermore, the levels of osteocalcin, bone-specific alkaline phosphatase and procollagen type-I N-pro-peptide (bone formation markers) increased from baseline to 4 months (secondary endpoints) by 18.4%, 92.6% and 10.2%, respectively. Furthermore, the median levels of dickkopf-1 and C-C motif ligand-3 showed a significant decrease at 4 months by 17.5% and 16.0%, respectively. In conclusion, daratumumab improved bone turnover by inducing bone formation and reducing osteoblast inhibition.

Real-life Experience With Rituximab-CHOP Every 21 or 14 Days in Primary Mediastinal Large B-cell Lymphoma.

BACKGROUND/AIM: Primary mediastinal large B-cell lymphoma (PMLBCL) is an aggressive B-cell non-Hodgkin lymphoma (NHL), whose prognosis has greatly improved since the incorporation of the anti-CD20 monoclonal antibody rituximab into current therapeutic regimens. Evidence, however, on the optimal time interval between consecutive chemoimmunotherapy (CIT) cycles is still scarce. This study aimed to evaluate the efficacy outcomes of the more commonly administered 3-weekly regimens to the biweekly ones in a PMLBCL patients' population, who were mostly treated with rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisolone every 21 days (R-CHOP-21) or R-CHOP-14. PATIENTS AND METHODS: We retrospectively studied our cohort of consecutively treated PMLBCL patients, focusing on their treatment density, in order to determine possible differences in treatment outcomes. RESULTS: CIT, in the form of both R-CHOP-21 as well as R-CHOP-14 (or similar regimens), is highly active in PMLBCL, with low rates of early treatment failure. In our cohort of patients, R-CHOP-14 did not result in a meaningful improvement of freedom from progression (FFP) or overall survival (OS). CONCLUSION: Both R-CHOP-14 and R-CHOP-21 are probably equally effective in PMLBCL, yet further, prospective, randomized studies are warranted to clarify whether dose-dense regimens can be associated with better disease control and long-term results.

Chronic myelogenous leukemia occurring in two brothers: The opposite sides of the same coin?

Herein we present a rare case of two brothers diagnosed with CML four years apart. Importantly, our case of CML occurrence among siblings is the fifth one reported and the second one investigated by both, conventional cytogenetics and RT-PCR analysis. Moreover, although Ph chromosome was detected in both our patients, RT-PCR revealed the presence of two different BCR-ABL transcripts. Finally, both our patients have been followed for a long period of time offering thus the opportunity to observe the differences in the clinical course.

Real-world data on incidence, clinical characteristics and outcome of patients with macrofocal multiple myeloma (MFMM) in the era of novel therapies: A study of the Greco-Israeli collaborative myeloma working group.

We investigated incidence, characteristics and outcome of patients with macrofocal multiple myeloma (MFMM) treated mainly with novel therapies. Based on definition (BMPCs <20% and lytic lesions/plasmacytomas, without anemia, renal insufficiency or hypercalcemia) we identified 140 patients with MFMM, among 4650 myeloma patients (3%). Twice the number of patients with typical myeloma were used as controls; 60% were <65 years and 70% had advanced bone disease. Plasmacytomas were more frequent in MFMM compared with standard myeloma (68% vs 15%, P < .05). Adverse prognostic parameters (high lactate dehydrogenase, advanced stage, high risk cytogenetics, immunoparesis) were less common in patients with MFMM compared with controls (P < .05); 90% received novel agents and 47% underwent autologous transplantation upfront; 90% achieved an objective response; 70% had at least very good partial response which was significantly higher compared with controls (P < .05). After a median follow-up of 52 months, 33 patients have died. Early death (<12 months) was infrequent in MFMM. Median progression-free survival and overall survival (OS) were 46 and 129 months respectively, both significantly longer compared with controls (P < .001). Proteasome inhibitor (PI)-based therapy was the only independent predictor for OS in the multivariate analysis (HR: 3.9; P < .001). In conclusion, MFMM is a distinct entity presented in young and elderly subjects, characterized by limited bone marrow infiltration, advanced bone disease and frequent presence of plasmacytomas; MFMM patients have less often adverse prognostic features and achieve excellent responses and prolonged OS especially when treated with PI-based therapies. Novel imaging will help in a more accurate classification of this entity.

Evaluation of regulatory T cells (Tregs) alterations in patients with multiple myeloma treated with bortezomib or lenalidomide plus dexamethasone: correlations with treatment outcome.

The exact role of regulatory T cells (Tregs) in multiple myeloma (MM) has not been yet determined. Data regarding alterations of Tregs during therapy with novel agents (NA), i.e., bortezomib and lenalidomide are conflicted and limited. We evaluated prospectively alterations of Tregs and searched for correlations with disease characteristics, response, and outcome in 29 patients with active MM treated with either bortezomib-dexamethasone (BD; 11 patients) or lenalidomide-dexamethasone (LenDex, 18 patients). Additionally, we recorded changes of lymphocytes subsets and cytokines related to Tregs function and MM biology, i.e., interleukin (IL) 6, 2, 17, and TGF-ß. Compared with controls, patients had significantly higher median levels of Tregs%, IL-6, and IL-17 (p < 0.001). Median CD4 T and B cells frequencies were significantly lower, whereas CD8 T and natural killers were increased compared to controls. In BD group, no significant alterations of Tregs% were observed. Patients treated with LenDex, displayed a significant reduction of Tregs% (p < 0.001) especially those who achieved at least very good partial response (≥vgPR) (p = 0.04). Lymphocyte subsets or cytokines did not significantly change during therapy. In summary, Tregs% are higher in patients with active MM compared with controls, and they significantly decrease after treatment with LenDex but not with BD; After therapy with LenDex, Tregs reduction between baseline and major response correlated with achievement of ≥vgPR suggesting a possible predictive role, that may contribute to therapeutic strategy.

Real-world data on prognosis and outcome of primary plasma cell leukemia in the era of novel agents: a multicenter national study by the Greek Myeloma Study Group.

We have studied the efficacy and the prognostic impact of novel agents in 50 primary plasma cell leukemia (pPCL) patients registered in our database. Eighty percent of patients were treated upfront with novel agent-based combinations; 40% underwent autologous stem cell transplantation (ASCT). Objective response rate was 76; 38% achieved at least very good partial response (≥vgPR) and this correlated significantly with bortezomib-based therapy plus ASCT. At the time of evaluation, 40 patients had died. Early mortality rate (≤1 month) was 6%. Median progression-free survival (PFS) and overall survival (OS) were 12 months and 18 months respectively, both significantly longer in patients treated with bortezomib-based therapy + ASCT vs. others (PFS: 18 vs. 9 months; p = 0.004, OS: 48 vs. 14 months; p = 0.007). Bortezomib-based therapy + ASCT predicted for OS in univariate analysis. In multivariate analysis, achievement of ≥vgPR and LDH ≥ 300 U/L were significant predictors for OS. These real-world data, based on one of the largest reported national multicenter series of pPCL patients treated mostly with novel agents support that, among the currently approved induction therapies, bortezomib-based regimens are highly effective and reduce the rate of early mortality whereas in combination with ASCT consolidation they prolong OS.

Lack of survival improvement with novel anti-myeloma agents for patients with multiple myeloma and central nervous system involvement: the Greek Myeloma Study Group experience.

Involvement of the central nervous system (CNS) is a rare complication of multiple myeloma (MM). Herein, we have described the incidence, characteristics, prognostic factors for post CNS-MM survival, and outcome of CNS-MM and explored the efficacy of novel agents (NA) (thalidomide, bortezomib, lenalidomide) in this setting. Between 2000 and 2013, 31 (0.9 %) out of 3408 newly diagnosed symptomatic MM patients, consecutively diagnosed and treated during the same period in 12 Greek centers, developed CNS-MM (M/F 15/16, median age 59 years, range 20-96 years; newly diagnosed/relapsed-refractory 2/29; median time to CNS-MM diagnosis 29 months). Clinical and laboratory characteristics were retrospectively recorded. Twenty-six percent of patients had circulating plasma cells (PCs) or plasma cell leukemia (PCL) at CNS-MM and 39 % had skull-derived plasmacytomas, suggesting hematological and contiguous spread. Treatment for CNS-MM was offered in 29/31 patients and 11/29 responded (NA 18/29, additional radiotherapy 9/28, intrathecal chemotherapy 13/29). The median post CNS-MM survival was 3 months (95 % CI 1.9-4.1) and did not differ between patients treated with NA and/or radiotherapy vs. others. In the multivariate analysis, prior treatment of MM with NA, extramedullary disease (EMD) during MM course (i.e., plasmacytomas, circulating PCs, or documented PCL) and abnormally high LDH at MM diagnosis were independent prognostic factors, whereas treatment of CNS-MM with NA did not predict for post CNS-MM survival. Despite the relatively limited number of patients due to the rarity of CNS-MM, our results suggest that NA do not seem to improve post CNS-MM survival. Patients with EMD display shortened post CNS-MM survival and should be followed thoroughly.

Clinical features, outcome, and prognostic factors for survival and evolution to multiple myeloma of solitary plasmacytomas: a report of the Greek myeloma study group in 97 patients.

Solitary plasmacytoma (SP) is a rare plasma cell dyscrasia characterized by the presence of bone or extramedullary plasma cell tumors. The treatment of choice is local radiotherapy (R/T) ± surgical excision. The role of adjuvant chemotherapy (C/T) or novel agents (NA) is uncertain. Data related to prognostic factors are inconclusive. Herein, we describe the clinical features, survival and prognosis of 97 consecutive patients, 65 with bone SP (SBP), and 32 with extramedullary SP (SEP), diagnosed and treated in 12 Greek Myeloma Centers. Objective response rate (≥PR) and complete response (CR) was 91.8% and 61.9%, respectively, and did not differ between the 2 groups. Overall, 38 patients relapsed or progressed to multiple myeloma (MM). After a median follow-up of 60 months, 5 and 10-year overall survival (OS) probability was 92% and 89% in SEP and 86% and 69% in SBP, respectively (P = 0.2). The 5- and 10-year MM-free survival (MMFS) probability was 90% and 70% for patients with SEP vs. 59% and 50% for patients with SBP, respectively (P = 0.054). Overall, the 5- and 10-year OS probability, plasmacytoma relapse-free survival (PRFS), progression-free survival and MMFS was 84% and 78%, 72% and 58%, 58% and 43%, and 70% and 59%, respectively. In the multivariate analysis, prolonged PRFS and young age were positive predictors of OS. Achievement of CR was the only positive predictor of PRFS. Immunoparesis was the only negative predictor of progression to MM. The addition of C/T or NA-based treatment increased toxicity without offering any survival advantage over R/T.

Treatment with bortezomib-based regimens improves overall response and predicts for survival in patients with primary or secondary plasma cell leukemia: Analysis of the Greek myeloma study group.

Plasma cell leukemia (PCL) is a rare and aggressive plasma cell disorder, with poor outcome. Bortezomib-based regimens (BBR) are highly effective in myeloma, but there is limited information about their efficacy and safety in PCL. Thus, we retrospectively collected data from 42 consecutive PCL patients (25 with primary PCL-pPCL and 17 with secondary PCL-sPCL) to explore the role of BBR in this entity. BBR were administered in 29 of 42 patients, while 6 of 25 patients with pPCL underwent autologous transplantation. Objective response (≥partial response) was significantly higher in patients treated with BBR versus conventional therapies (69% vs. 30.8%, P = 0.04); 27.5% of patients treated with BBR achieved at least very good partial response (vgPR). The highest ORR was observed in pPCL patients treated with BBR (88.9%; ≥vgPR: 33.3%). In BBR-group, grade 3 of 4 hematological, neurological and renal toxicity and neutropenic infections were observed in 41.4%, 7%, 3.4%, and 31%, respectively. With a median follow-up of 51 months, median overall survival (OS) for patients treated with BBR versus conventional therapies was 13 versus 2 months (P < 0.007). Median OS of patients with pPCL and sPCL treated with BBR was 18 and 7 months, respectively (P < 0.001). In the multivariate analysis normal PLTs, treatment with BBR and high quality response were the only powerful predictors for survival. Our study carrying the longest reported median follow-up, demonstrated that treatment of PCL with BBR induces high response rates and prolongs survival over conventional therapies, regardless of additional autologous transplantation rescue or established high risk features, with manageable toxicity.

Tumor-primed natural killer cells from patients with multiple myeloma lyse autologous, NK-resistant, bone marrow-derived malignant plasma cells.

Natural killer (NK) cells are cytotoxic lymphocytes able to kill tumor cells and virus-infected cells. Human-resting NK cells can be activated by co-culture with NK-resistant CTV-1a cells. These tumor-activated cells (TaNKs) are cytotoxic to a range of NK-resistant tumor cells in vitro. This potential, however, has not been explored in multiple myeloma (MM). In this study, we demonstrate that TaNK cells from 21 MM patients lyse a variety of myeloma targets, including primary isolates of autologous and allogeneic CD138+ myeloma cells whilst sparing CD138-ve bone marrow cells. Myeloma patients' TaNK-induced lysis of the U266 cell line was significantly higher compared to normal controls (median-specific lysis 79.1% vs. 69.5%) (P = 0.003). In addition, TaNKs induced substantial lysis of autologous and allogeneic CD138+ myeloma cells (median-specific lysis 52.5% and 37.4%, respectively). The percentage of specific lysis did not correlate with important disease characteristics (ISS, age, and high-risk molecular abnormalities) or with the disease status and antimyeloma treatment, including novel agents and dexamethasone. In conclusion, tumor-primed NK cells are able to induce substantial lysis of myeloma targets including autologous and allogeneic CD138+ myeloma plasma cells and could be an additional therapeutic approach in MM, particularly in the era of novel agents.

Longitudinal cohort study of risk factors in cancer patients of bisphosphonate-related osteonecrosis of the jaw.

PURPOSE: The reported incidence of osteonecrosis of the jaw (ONJ) ranges from 0.94% to 18.6%. This cohort study aimed to calculate the incidence of and identify the risk factors for ONJ in patients with cancer treated with intravenous zoledronate, ibandronate, and pamidronate. PATIENTS AND METHODS: Data analyzed included age, sex, smoking status, underlying disease, medical and dental history, bisphosphonates (BP) type, and doses administered. Relative risks, crude and adjusted odds ratios (aORs), and cumulative hazard ratios for ONJ development were calculated. RESULTS: We included 1,621 patients who received 29,006 intravenous doses of BP, given monthly. Crude ONJ incidence was 8.5%, 3.1%, and 4.9% in patients with multiple myeloma, breast cancer, and prostate cancer, respectively. Patients with breast cancer demonstrated a reduced risk for ONJ development, which turned out to be nonsignificant after adjustment for other variables. Multivariate analysis demonstrated that use of dentures (aOR = 2.02; 95% CI, 1.03 to 3.96), history of dental extraction (aOR = 32.97; 95% CI, 18.02 to 60.31), having ever received zoledronate (aOR = 28.09; 95% CI, 5.74 to 137.43), and each zoledronate dose (aOR = 2.02; 95% CI, 1.15 to 3.56) were associated with increased risk for ONJ development. Smoking, periodontitis, and root canal treatment did not increase risk for ONJ in patients receiving BP. CONCLUSION: The conclusions of this study validated dental extractions and use of dentures as risk factors for ONJ development. Ibandronate and pamidronate at the dosages and frequency used in this study seem to exhibit a safer drug profile concerning ONJ complication; however, randomized controlled trials are needed to validate these results. Before initiation of a bisphosphonate, patients should have a comprehensive dental examination. Patients with a challenging dental situation should have dental care attended to before initiation of these drugs.

Cystatin-C is an independent prognostic factor for survival in multiple myeloma and is reduced by bortezomib administration.

BACKGROUND: Renal impairment is a common complication of multiple myeloma. Cystatin-C is considered an accurate marker of glomerular filtration rate in several renal disorders. Microarray analysis has revealed that cystatin-C is one of the most highly up-regulated genes in multiple myeloma. The aim of this study was to evaluate the serum levels of cystatin-C in myeloma patients, explore possible correlations with clinical data, including survival, and assess the effect of bortezomib on cystatin-C in relapsed multiple myeloma. DESIGN AND METHODS: We measured serum cystatin-C in 157 newly diagnosed, previously untreated myeloma patients, in 28 patients with relapsed disease pre- and post-bortezomib therapy and in 52 healthy controls, using a latex particle-enhanced nephelometric immunoassay. RESULTS: In newly diagnosed patients, cystatin-C was elevated and showed strong correlations with advanced ISS stage, extensive bone disease, high beta(2)-microglobulin, high serum creatinine, and low creatinine clearance. Multivariate analysis revealed that only cystatin-C and lactate dehydrogenase had an independent prognostic impact on patients' survival. The combination of cystatin-C and lactate dehydrogenase revealed three prognostic groups of patients: a high-risk group (both elevated cystatin-C and lactate dehydrogenase) with a median survival of 24 months, an intermediate-risk group (elevated cystatin-C or elevated lactate dehydrogenase) with a median survival of 48 months and a low-risk group (both low cystatin-C and lactate dehydrogenase) in which median survival has not yet been reached (p<0.001). Cystatin-C could also identify a subset of ISS-II patients with worse outcome. Relapsed patients had higher cystatin-C levels even compared to newly diagnosed patients. Treatment with bortezomib produced a significant reduction of cystatin-C, mainly in responders. CONCLUSIONS: Serum cystatin-C is not only a sensitive marker of renal impairment but also reflects tumor burden and is of prognostic value in myeloma. Its reduction after treatment with bortezomib reflects bortezomib's anti-myeloma activity and possibly bortezomib's direct effect on renal function.