Conventionally-Defined and PET/CT-Defined Complete Response (CR) to Novel Agent-Based Induction Therapy and Autologous Stem-Cell Transplantation (ASCT) In Multiple Myeloma (MM): A Prospective Study of Clinical and Prognostic Implications

• Published in: Blood 2011-11, Vol.118 (21), p.826-826
• Main Authors: Zamagni, Elena, Nanni, Cristina, Patriarca, Francesca, Pezzi, Annalisa, Zannetti, Beatrice Anna, Tacchetti, Paola, Englaro, Emanuela, Perrone, Giulia, Buttignol, Silvia, Brioli, Annamaria, Pantani, Lucia, Carobolante, Francesca, Baccarani, Michele, Fanti, Stefano, Cavo, Michele
• Format: Article
• Language: English
• ISSN: 0006-4971; 1528-0020
• DOI: 10.1182/blood.V118.21.826.826

Abstract 826 Incorporation of novel agents into ASCT allowed the achievement of unprecedented high rates of CR in young MM patients, a gain which translated into extended PFS and OS. As a consequence, interest in the evaluation of the depth of CR has progressively grown. More sensitive tools, such as multiparametric flow cytometry or molecular biology, led to the demonstration of a correlation between the depth of CR and prognosis, but failed to identify the persistence of residual disease outside of the bone marrow level. 18 F-FDG PET/CT is a careful technique to detect with high sensitivity and specificity the presence of active bone lesions and/or bone marrow involvement in newly diagnosed and previously treated MM. We prospectively analysed the prognostic significance of FDG-PET/CT at diagnosis, after induction therapy and ASCT in an homogeneous population of 192 patients with newly diagnosed MM, followed for a median of 43 months. By study design, all patients were studied with FDG-PET/CT at baseline, after induction treatment, after 3 months from ASCT (single or double), once a year during the maintenance/follow-up phase and at time of relapse. Bone marrow involvement was described as negative, diffuse or focal. The number of focal lesions (FLs), as well as size and associated standardized uptake values (SUV) were recorded. Extra-medullary disease (EMD), if present, was described by location, size, number and SUV. Twenty four percent of the patients had a negative PET/CT scan at diagnosis. Among PET/CT-positive patients, 44% showed ≥3 FLs, 46% had SUV values >4.2 and in 6% EMD could be detected. These 3 variables adversely affected 4-year estimates of PFS and OS. In particular, both EMD and severe FDG uptake were significantly associated with shorter PFS and OS. Thirty seven percent of the patients were PET/CT-negative after induction. A strong correlation between conventional response and SUV max reduction was evident, the mean SUV value of patients achieving CR being significantly lower in comparison with that of patients reaching very good partial response (VGPR) or partial response (mean: 1.4 vs 3, respectively) (Cuzick’s trend test, P= 0.016). Persistence of severe FDG uptake (SUV max still >4.2) after induction predicted for shorter PFS at 4 years (P= 0.004). PET/CT negativity (PET-CR) was observed in 65% of patients after 3 months from ASCT(s). A close relationship between PET/CT negativity and response to ASCT was evident, since 95% of patien