Single-Cell DNA Sequencing Reveals an Evolutionary Pattern of CHIP in Transplant Eligible Multiple Myeloma Patients.

Clonal hematopoiesis of indeterminate potential (CHIP) refers to the phenomenon where a hematopoietic stem cell acquires fitness-increasing mutation(s), resulting in its clonal expansion. CHIP is frequently observed in multiple myeloma (MM) patients, and it is associated with a worse outcome. High-throughput amplicon-based single-cell DNA sequencing was performed on circulating CD34+ cells collected from twelve MM patients before autologous stem cell transplantation (ASCT). Moreover, in four MM patients, longitudinal samples either before or post-ASCT were collected. Single-cell sequencing and data analysis were assessed using the MissionBio Tapestri® platform, with a targeted panel of 20 leukemia-associated genes. We detected CHIP pathogenic mutations in 6/12 patients (50%) at the time of transplant. The most frequently mutated genes were TET2, EZH2, KIT, DNMT3A, and ASXL1. In two patients, we observed co-occurring mutations involving an epigenetic modifier (i.e., DNMT3A) and/or a gene involved in splicing machinery (i.e., SF3B1) and/or a tyrosine kinase receptor (i.e., KIT) in the same clone. Longitudinal analysis of paired samples revealed a positive selection of mutant high-fitness clones over time, regardless of their affinity with a major or minor sub-clone. Copy number analysis of the panel of all genes did not show any numerical alterations present in stem cell compartment. Moreover, we observed a tendency of CHIP-positive patients to achieve a suboptimal response to therapy compared to those without. A sub-clone dynamic of high-fitness mutations over time was confirmed.

Multi-dimensional scaling techniques unveiled gain1q&loss13q co-occurrence in Multiple Myeloma patients with specific genomic, transcriptional and adverse clinical features.

The complexity of Multiple Myeloma (MM) is driven by several genomic aberrations, interacting with disease-related and/or -unrelated factors and conditioning patients' clinical outcome. Patient's prognosis is hardly predictable, as commonly employed MM risk models do not precisely partition high- from low-risk patients, preventing the reliable recognition of early relapsing/refractory patients. By a dimensionality reduction approach, here we dissect the genomic landscape of a large cohort of newly diagnosed MM patients, modelling all the possible interactions between any MM chromosomal alterations. We highlight the presence of a distinguished cluster of patients in the low-dimensionality space, with unfavorable clinical behavior, whose biology was driven by the co-occurrence of chromosomes 1q CN gain and 13 CN loss. Presence or absence of these alterations define MM patients overexpressing either CCND2 or CCND1, fostering the implementation of biology-based patients' classification models to describe the different MM clinical behaviors.

Severe SARS-CoV-2 and subsequent fungal infections after CAR T-cell therapy for relapsed/refractory multiple myeloma: a challenging and happy ending fight.

Chimeric antigen receptor (CAR) T-cells have unveiled a promising therapeutic horizon for relapsed/refractory multiple myeloma (R/R MM). Nevertheless, immune impairment induced by cellular therapies, previous treatments and MM itself could promote infectious events. COVID-19 could evolve into a life-threating infection in R/R MM patients who often have suboptimal responses to SARS-CoV-2 vaccines. Here, we describe a case of severe and long-lasting COVID-19 pneumonia after CAR T-cell therapy for R/R MM requiring a complex clinical management. Long-term infectious complications in MM patients undergoing CAR T-cells should be taken into consideration as they could counteract the efficacy of this new treatment.

High levels of CRBN isoform lacking IMiDs binding domain predicts for a worse response to IMiDs-based upfront therapy in newly diagnosed myeloma patients.

In recent years, the immunoderivative (IMiD) agents have been extensively used for the treatment of multiple myeloma (MM). IMiDs and their newer derivatives CRBN E3 ligase modulator bind the E3 ligase substrate recognition adapter protein cereblon (CRBN), which has been recognized as one of the IMiDs' direct target proteins, and it is essential for the therapeutic effect of these agents.High expression of CRBN was associated with improved clinical response in patients with MM treated with IMiDs, further confirming that the expression of IMiDs' direct target protein CRBN is required for the anti-MM activity. CRBN's central role as a target of IMiDs suggests potential utility as a predictive biomarker of response or resistance to IMiDs therapy. Additionally, the presence of alternatively spliced variants of CRBN in MM cells, especially those lacking the drug-binding domain for IMiDs, raise questions concerning their potential biological function, making difficult the transcript measurement, which leads to inaccurate overestimation of full-length CRBN transcripts. In sight of this, in the present study, we evaluated the CRBN expression, both full-length and spliced isoforms, by using real-time assay data from 87 patients and RNA sequencing data from 50 patients (n = 137 newly diagnosed MM patients), aiming at defining CRBN's role as a predictive biomarker for response to IMiDs-based induction therapy. We found that the expression level of the spliced isoform tends to be higher in not-responding patients, confirming that the presence of a more CRBN spliced transcript predicts for lack of IMiDs response.

Long term follow-up of humoral and cellular response to mRNA-based vaccines for SARS-CoV-2 in patients with active multiple myeloma.

Long-term kinetics of antibody (Ab) and cell-mediated immune (CMI) response to full anti-SARS-CoV-2 vaccine schedule and booster doses in Multiple Myeloma (MM) patients remain unclear. We prospectively evaluated Ab and CMI response to mRNA vaccines in 103 SARS-CoV-2-naïve MM patients (median age 66, 1 median prior line of therapy) and 63 health-workers. Anti-S-RBD IgG (Elecsys®assay) were measured before vaccination and after 1 (T1), 3 (T3), 6 (T6), 9 (T9) and 12 (T12) months from second dose (D2) and 1 month after the introduction of the booster dose (T1D3). CMI response (IGRA test) was evaluated at T3 and T12. Fully vaccinated MM patients displayed high seropositivity rate (88.2%), but low CMI response (36.2%). At T6 the median serological titer was halved (p=0.0391) in MM patients and 35% reduced (p=0.0026) in controls. D3 (94 patients) increased the seroconversion rate to 99% in MM patients and the median IgG titer in both groups (up to 2500 U/mL), maintained at T12. 47% of MM patients displayed a positive CMI at T12 and double-negativity for humoral and CMI (9.6% at T3) decreased to 1%. Anti-S-RBD IgG level ≥346 U/mL showed 20-times higher probability of positive CMI response (OR 20.6, p<0.0001). Hematological response ≥CR and ongoing lenalidomide maintenance enhanced response to vaccination, hindered by proteasome inhibitors/anti-CD38 monoclonal antibodies. In conclusion, MM elicited excellent humoral, but insufficient cellular responses to anti-SARS-CoV-2 mRNA vaccines. Third dose improved immunogenicity renewal, even when undetectable after D2. Hematological response and ongoing treatment at vaccination were the main predictive factors of vaccine immunogenicity, emphasizing the role of vaccine response assessment to identify patients requiring salvage approaches.

Role of serum-free light chain assay for defining response and progression in immunoglobulin secretory multiple myeloma.

The International Myeloma Working Group (IMWG) guidelines recommend using electrophoresis and immunofixation to define response and progressive disease (PD) in immunoglobulin (Ig) secretory multiple myeloma (Ig-MM), whereas the role of serum-free light chain (sFLC) is controversial. We retrospectively analyzed the value of adding sFLC assays in the definition of response and PD according to IMWG criteria in 339 Ig-MM patients treated with a first-line novel agent-based therapy (median follow-up 54 months). sFLC PD was defined according to conventional criteria plus increased sFLC levels, or sFLC escape (sFLCe); progression/sFLCe-free survival (ePFS) was the time from the start of treatment to the date of first PD or sFLCe, or death; overall survival after PD/sFLCe (OS after Pe) was the time from first PD or sFLCe to the date of death. 148 (44%) patients achieved a complete response and 198 (60%) a normal sFLC ratio (sFLCR). sFLCR normalization was an independent prognostic factor for extended PFS (HR = 0.46, p = 0.001) and OS (HR = 0.47, p = 0.006) by multivariable analysis. 175 (52%) patients experienced PD according to the IMWG criteria, whereas 180 (53%) experienced PD or sFLCe. Overall, a sFLCe was observed in 31 (9%) patients. Median PFS and ePFS were both equal to 36 (95% CI = 32-42, and 32-40, respectively) months. sFLC PD adversely affected the OS after Pe compared to PD with increasing monoclonal Ig only (HR = 0.52, p = 0.012). Our results support the inclusion of the sFLC assay for defining response and PD in Ig-MM.

Identification of a Maturation Plasma Cell Index through a Highly Sensitive Droplet Digital PCR Assay Gene Expression Signature Validation in Newly Diagnosed Multiple Myeloma Patients.

DNA microarrays and RNA-based sequencing approaches are considered important discovery tools in clinical medicine. However, cross-platform reproducibility studies undertaken so far have highlighted that microarrays are not able to accurately measure gene expression, particularly when they are expressed at low levels. Here, we consider the employment of a digital PCR assay (ddPCR) to validate a gene signature previously identified by gene expression profile. This signature included ten Hedgehog (HH) pathways' genes able to stratify multiple myeloma (MM) patients according to their self-renewal status. Results show that the designed assay is able to validate gene expression data, both in a retrospective as well as in a prospective cohort. In addition, the plasma cells' differentiation status determined by ddPCR was further confirmed by other techniques, such as flow cytometry, allowing the identification of patients with immature plasma cells' phenotype (i.e., expressing CD19+/CD81+ markers) upregulating HH genes, as compared to others, whose plasma cells lose the expression of these markers and were more differentiated. To our knowledge, this is the first technical report of gene expression data validation by ddPCR instead of classical qPCR. This approach permitted the identification of a Maturation Index through the integration of molecular and phenotypic data, able to possibly define upfront the differentiation status of MM patients that would be clinically relevant in the future.

The ALLgorithMM: How to define the hemodilution of bone marrow samples in lymphoproliferative diseases.

Introduction: Minimal residual disease (MRD) is commonly assessed in bone marrow (BM) aspirate. However, sample quality can impair the MRD measurement, leading to underestimated residual cells and to false negative results. To define a reliable and reproducible method for the assessment of BM hemodilution, several flow cytometry (FC) strategies for hemodilution evaluation have been compared. Methods: For each BM sample, cells populations with a well-known distribution in BM and peripheral blood - e.g., mast cells (MC), immature (IG) and mature granulocytes (N) - have been studied by FC and quantified alongside the BM differential count. Results: The frequencies of cells' populations were correlated to the IG/N ratio, highlighting a mild correlation with MCs and erythroblasts (R=0.25 and R=0.38 respectively, with p-value=0.0006 and 0.0000052), whereas no significant correlation was found with B or T-cells. The mild correlation between IG/N, erythroblasts and MCs supported the combined use of these parameters to evaluate BM hemodilution, hence the optimization of the ALLgorithMM. Once validated, the ALLgorithMM was employed to evaluate the dilution status of BM samples in the context of MRD assessment. Overall, we found that 32% of FC and 52% of Next Generation Sequencing (NGS) analyses were MRD negative in samples resulted hemodiluted (HD) or at least mildly hemodiluted (mHD). Conclusions: The high frequency of MRD-negative results in both HD and mHD samples implies the presence of possible false negative MRD measurements, impairing the correct assessment of patients' response to therapy and highlighs the importance to evaluate BM hemodilution.

Survival Risk Scores for Real-Life Relapsed/Refractory Multiple Myeloma Patients Receiving Elotuzumab or Carfilzomib In Combination With Lenalidomide and Dexamethasone as Salvage Therapy: Analysis of 919 Cases Outside Clinical Trials.

The present study aimed to develop two survival risk scores (RS) for overall survival (OS, SRS KRd/EloRd ) and progression-free survival (PFS, PRS KRd/EloRd ) in 919 relapsed/refractory multiple myeloma (RRMM) patients who received carfilzomib, lenalidomide, and dexamethasone (KRd)/elotuzumab, lenalidomide, and dexamethasone (EloRd). The median OS was 35.4 months, with no significant difference between the KRd arm versus the EloRd arm. In the multivariate analysis, advanced ISS (HR = 1.31; P = 0.025), interval diagnosis-therapy (HR = 1.46; P = 0.001), number of previous lines of therapies (HR = 1.96; P < 0.0001), older age (HR = 1.72; P < 0.0001), and prior lenalidomide exposure (HR = 1.30; P = 0.026) remained independently associated with death. The median PFS was 20.3 months, with no difference between the two strategies. The multivariate model identified a significant progression/death risk increase for ISS III (HR = 1.37; P = 0.002), >3 previous lines of therapies (HR = 1.67; P < 0.0001), older age (HR = 1.64; P < 0.0001), and prior lenalidomide exposure (HR = 1.35; P = 0.003). Three risk SRS KRd/EloRd categories were generated: low-risk (134 cases, 16.5%), intermediate-risk (467 cases, 57.3%), and high-risk categories (213 cases, 26.2%). The 1- and 2-year OS probability rates were 92.3% and 83.8% for the low-risk (HR = 1, reference category), 81.1% and 60.6% (HR = 2.73; P < 0.0001) for the intermediate-risk, and 65.5% and 42.5% (HR = 4.91; P < 0.0001) for the high-risk groups, respectively. Notably, unlike the low-risk group, which did not cross the median timeline, the OS median values were 36.6 and 18.6 months for the intermediate- and high-risk cases, respectively. Similarly, three PRS KRd/EloRd risk categories were engendered. Based on such grouping, 338 (41.5%) cases were allocated in the low-, 248 (30.5%) in the intermediate-, and 228 (28.0%) in the high-risk groups. The 1- and 2-year PFS probability rates were 71.4% and 54.5% for the low-risk (HR = 1, reference category), 68.9% and 43.7% (HR = 1.95; P < 0.0001) for the intermediate-risk, and 48.0% and 27.1% (HR = 3.73; P < 0.0001) for the high-risk groups, respectively. The PFS median values were 29.0, 21.0, and 11.7 months for the low-, intermediate-, and high-risk cases. This analysis showed 2.7- and 4.9-fold increased risk of death for the intermediate- and high-risk cases treated with KRd/EloRd as salvage therapy. The combined progression/death risks of the two categories were increased 1.3- and 2.2-fold compared to the low-risk group. In conclusion, SRS KRd/EloRd and PRS KRd/EloRd may represent accessible and globally applicable models in daily clinical practice and ultimately represent a prognostic tool for RRMM patients who received KRd or EloRd.

Adjusted comparison between elotuzumab and carfilzomib in combination with lenalidomide and dexamethasone as salvage therapy for multiple myeloma patients.

The lack of a randomized trial comparing carfilzomib (K) versus elotuzumab (Elo) associated with lenalidomide and dexamethasone (Rd) prompted us to assess the relative usefulness of one triplet over the other. Five independent retrospective cohorts of 883 relapsed/refractory multiple myeloma (RRMM) patients, including 300 EloRd and 583 KRd cases, outside clinical trials, entered this non-randomized comparison. KRd cohort accounted for a higher incidence of younger patients, cases with ≥3 lines of therapy, already exposed to lenalidomide, International Staging System (ISS) stage III, and abnormal lactic dehydrogenase (LDH) level compared with EloRd cohort. Moreover, cytogenetic risk categories, detected in roughly one-third of cases, were equally distributed between the two therapy arms. The probability of CR+VGPR response was significantly higher in KRd (n = 314, 53.9%) than in EloRd patients (n = 111, 37.0%). Likewise, the cumulative incidence function of CR+VGPR, taking into account the competitive risk of death, was significantly higher in KRd arm patients than those in the EloRd arm (p = .003). Moreover, KRd treatment significantly reduced the progression or death risk by 46% in an adjusted multivariate analysis (HR: 0.54, 95% CI 0.42-0.69, p < .0001). Finally, in an adjusted illness-progression/death model, the effect of KRd versus EloRd was of higher magnitude among those who achieved CR+VGPR (-39% hazard ratio reduction, p = .02) than among those who achieved < VGPR (-29% hazard ratio reduction, p = .007). With limitations characteristic to any retrospective analysis, this current clinical practice study's overall results demonstrated potential benefits of KRd therapy compared with EloRd. This observation may help the daily clinical practice.

Emerging and current treatment combinations for transplant-ineligible multiple myeloma patients.

INTRODUCTION: Availability of new classes of novel agents has led to a radical switch in treatment paradigms for newly diagnosed transplant-ineligible multiple myeloma (NDTIMM) patients, providing an opportunity to significantly enhance the depth of response and extend survival outcomes. AREAS COVERED: Treatment regimens including proteasome inhibitors (PIs), immunomodulatory drugs (IMiDs) and/or monoclonal antibodies (mAbs), have achieved recent regulatory approval for NDTIMM, while novel combinations and newer agents are currently being explored. This review discusses the current landscape and possible treatment development of NDTIMM. EXPERT OPINION: Bortezomib-lenalidomide-dexamethasone (VRd), daratumumab-bortezomib-melphalan-prednisone (DaraVMP) and daratumumab-lenalidomide-dexamethasone (DaraRd) represent new standard of care (SOC) treatments for NDTIMM patients, based on phase III trials showing their superior efficacy as compared with previous SOCs. The possibility of improving results by incorporating second generation PIs or using quadruple regimens has also been explored and different trials are still ongoing. Newer agents and innovative immunotherapies targeting B-cell maturation antigen have the potential to change the therapeutic landscape in coming years. Personalized approaches based on frailty-adapted, risk-based and minimal residual disease driven paradigms are under investigation.

Subcutaneous bortezomib-containing regimens as up-front treatment of newly diagnosed transplant-eligible multiple myeloma patients: a retrospective, non-interventional observational study.

Subcutaneous (SC) bortezomib-based regimens represent the standard induction therapy prior to autologous stem cell transplantation (ASCT) in newly diagnosed multiple myeloma patients. Published data are based principally on intravenous (IV) administration: this retrospective observational study aimed to define patients' outcomes upon SC bortezomib administration, before and after ASCT. Of 131 enrolled patients, 86% received bortezomib-dexamethasone plus thalidomide (VTD), 5% plus cyclophosphamide (VCD), and 9% alone (VD), for a median of 4 cycles induction therapy, followed by single (52%) or double (48%) ASCT. 48 patients received consolidation with the same induction regimen. 35% had at least one adverse event, mainly gastrointestinal disorders and peripheral neuropathy (PN). ORR was 93.1%, 97.7% and 100%, after induction, ASCT(s) and consolidation, respectively. Median PFS and PFS2 were 55.8 months and 72 months, respectively, (median follow-up 45.3 months), while median OS was unreached. Concluding, SC bortezomib has similar efficacy with reduced PN than IV administration.

A real-world efficacy and safety analysis of combined carfilzomib, lenalidomide, and dexamethasone (KRd) in relapsed/refractory multiple myeloma.

Carfilzomib-lenalidomide-dexamethasone (KRd) has been approved for the treatment of relapsed/refractory multiple myeloma (RRMM). We conducted a retrospective analysis of 197 RRMM patients (pts) between January 2016 and March 2018 in six Italian hematologic centers, with the aim to evaluate efficacy and safety of KRd in real-life. At KRd initiation 27% carried high risk cytogenetic abnormalities (HRCA) [del17p and/or t(4;14) and/or t(14;16)], median number of prior lines of therapy was 2 (1-8), nearly all pts (96%) received prior bortezomib (18% refractory) while 45% were exposed to lenalidomide (R; 22% refractory). At the median of 12.5 months, 52% of the pts had discontinued treatment, mainly (66%) for progression. Main grade 3-4 adverse events were neutropenia (21%), infections (11%), and hypertension (6%). Overall, the response rate was 88%. The median progression-free survival (PFS) was 19.8 months and 1-year overall survival (OS) rate was 80.6%. By subgroup analysis, extended PFS and OS were observed for pts who received ≤2 prior lines of therapy (HR = 0.42, p < 0.001 and HR = 0.35, p = 0.001, respectively), not refractory to prior R (HR = 0.37, p < 0.001, and HR = 0.47, p = 0.024), without HRCA (HR = 0.33, p = 0.005 and HR = 0.26, p = 0.016) and achieving ≥ very good partial response (VGPR; HR = 0.17, p < 0.001 and HR = 0.18, p < 0.001). In conclusion, KRd demonstrated to be effective in RRMM pts treated in real-world setting, without new safety concerns. Better survival outcomes emerged for pts with ≤2 prior lines of therapy, achieving at least a VGPR, and without HRCA.

Successful treatment of bilateral endogenous Fusarium solani endophthalmitis in a patient with acute lymphocytic leukaemia.

Fusarium spp. are an uncommon cause of fungaemia in immunocompromised and neutropenic patients that may hematogenously disseminate to the eyes. Herein, we describe a patient with acute lymphoblastic leukaemia and a prior history of extensive corticosteroid exposure who developed disseminated Fusarium solani infection following chemotherapy despite posaconazole prophylaxis. She was successfully treated with combination liposomal amphotericin B and voriconazole, intraocular injections of voriconazole, topical amphotericin B and bilateral vitrectomy. We also review published literature describing the management of endogenous Fusarium endophthalmitis in immunocompromised hosts.

Novel agent-based salvage autologous stem cell transplantation for relapsed multiple myeloma.

High-dose chemotherapy followed by autologous stem cell transplantation (ASCT) is a standard frontline therapy for multiple myeloma (MM). Therapeutic options for patients with relapsed MM after ASCT include novel agents in different combos, salvage ASCT (sASCT), and allogeneic transplant, with no unique standard of care. We retrospectively analyzed 66 MM patients who relapsed after up-front single or double ASCT(s) and received novel agent-based sASCT at five Italian centers. Median event-free survival from up-front ASCT(s) to first relapse (EFS1) was 44 months. Seventy-three percent of patients received sASCT at first disease progression. Re-induction regimens were bortezomib based in 87% of patients. Response to re-induction therapy included complete response (CR) 18%, ≥ very good partial response (VGPR) 48%, and overall response rate (ORR) 83%. Response to sASCT included CR 44%, ≥ VGPR 77%, and ORR 94%. With a median follow-up of 24 months after sASCT, 39 patients experienced disease progression. Median EFS from sASCT (EFS2) was 17 months. Median overall survival from ASCT (OS1) and sASCT (OS2) was 166 and 43 months, respectively. EFS2 and OS2 were significantly shorter in patients with EFS1 ≤ 24 months, in patients who did not receive sASCT at first disease progression and in patients with extramedullary disease (EMD). In multivariate analysis, EFS1 ≤ 24 months was associated with shorter EFS2 and OS2, EMD was associated with shorter EFS2, and < CR after sASCT was associated with shorter OS2. Novel agent-based sASCT is a safe and effective procedure for relapsed MM.

Prognostic impact of serial measurements of serum-free light chain assay throughout the course of newly diagnosed multiple myeloma treated with bortezomib-based regimens.

We retrospectively investigated the role of serial serum-free light chain (sFLC) evaluations in 150 multiple myeloma (MM) patients treated with first-line bortezomib-based regimens. Baseline sFLC ratio (sFLCR) identified three groups of patients - normal, lightly abnormal (<100), and highly abnormal (≥100) - with different progression-free survival (PFS: 3-year estimate 72% versus 61% versus 44%, respectively, p = 0.03). Moreover, the achievement of a normal sFLCR correlated with extended PFS (49 versus 17 months, p < 0.0001) and overall survival (75 versus 43 months, p < 0.0001) as compared with abnormal sFLCR, a gain maintained in a multivariate analysis for PFS. At relapse, a high sFLCR was associated with earlier start of salvage therapy compared with sFLCR <100 (3-month probability: 89% versus 64%, p = 0.0426). In 20% of patients, sFLC escape preceded the conventional relapse by a median of 3.8 months. Our results highlight the role of sFLC assay in the prognosis and follow-up of MM.

PET/CT Improves the Definition of Complete Response and Allows to Detect Otherwise Unidentifiable Skeletal Progression in Multiple Myeloma.

PURPOSE: To evaluate the role of 18F-FDG PET/CT in 282 symptomatic multiple myeloma patients treated up-front between 2002 and 2012. EXPERIMENTAL DESIGN: All patients were studied by PET/CT at baseline, during posttreatment follow-up, and at the time of relapse. Their median duration of follow-up was 67 months. RESULTS: Forty-two percent of the patients at diagnosis had >3 focal lesions, and in 50% SUVmax was >4.2; extramedullary disease was present in 5%. On multivariate analysis, ISS stage 3, SUVmax >4.2, and failure to achieve best complete response (CR) were the leading factors independently associated with shorter progression-free survival (PFS) and overall survival (OS). These 3 variables were used to construct a prognostic scoring system based on the number of risk factors. After treatment, PET/CT negativity (PET-neg) was observed in 70% of patients, whereas conventionally defined CR was achieved in 53%. Attainment of PET-neg favorably influenced PFS and OS. PET-neg was an independent predictor of prolonged PFS and OS for patients with conventionally defined CR. Sixty-three percent of patients experienced relapse or progression; in 12%, skeletal progression was exclusively detected by systematic PET/CT performed during follow-up. A multivariate analysis revealed that persistence of SUVmax >4.2 following first-line treatment was independently associated with exclusive PET/CT progression. CONCLUSIONS: PET/CT combined with ISS stage and achievement or not of CR on first-line therapy sorted patients into different prognostic groups. PET/CT led to a more careful evaluation of CR. Finally, in patients with persistent high glucose metabolism after first-line treatment, PET/CT can be recommended during follow-up, to screen for otherwise unidentifiable progression.