Clinical and Epidemiological Characteristics of Multiple Myeloma (MM): Comparison Between Hematopoietic Stem Cell Transplantation (HSCT) and Conventional Chemotherapy,

The purpose of this epidemiological retrospective study was to describe the natural history, clinical features, treatment and outcome of a wide population of multiple myeloma (MM) patients during a 2-year period.

Data from 338 patients' files from 37 Spanish centers were collected during 2009. Included patients had ISS stage II-III MM and started first line treatment according to daily practice between Sep'03-Aug'05. Response rate (RR) following IMWG criteria and survival from diagnosis are analyzed in patients either with or without hematopoietic stem cell transplantation (HSCT). Because immunotechniques were not always available back then, stringent complete response is categorized as complete response (CR) and very good partial response as partial response (PR). Statistics on survival are calculated using univarite Cox analyses, and Chi-square and Fisher exact test are used for categorical results; valid percentages are presented.

Patients had a median of 66 (21–88) years of age at the time of diagnosis, good to moderate ECOG performance status (0–1, 50%; 2, 25%), and 1:1 ratio male:female. Besides staging II (42%) or III (58%) MM, most (95%) exhibited secretory disease, and bone lesions were common (73%). Anemia (hemoglobin <12 g/dl) was present initially in 80% of patients, hypercalcemia (calcium level ≥11 mg/dl) in 26%, and a serum creatinine level of 2 mg/dl or more in 27%. Of the 167 candidates to HSCT, 39 patients did not receive the therapy, mainly due to progression after induction (n=12), patient's decision (n=6), HSC mobilization failure (n=4), or death (n=4). Reasons for not being HSCT candidate included older age (n=112) and concomitant diseases (n=12). Table 1 resumes treatment regimens, efficacy, toxicity and survival of transplanted (T) and non-transplanted (NT) cohorts. Indution mainly consisted of conventional chemotherapy as new anti-myeloma therapies were not available during the study period. Most patients (93%) undergoing HSCT had melphalan conditioning; subsequent maintenance was given to 61 patients: interferon (75%), prednisone+/−interferon (10%), thalidomide (5%), and bortezomib (3%). Only 35 patients (9 in the T cohort) were given a second line of treatment. Objective RR (ORR=CR+PR) was higher in T than NT patients (95% vs 53%), even when both received similar chemotherapy combination, VBDA/VBMCP (94% vs 71%). When compared to this regimen, MP and VAD were significantly less effective in NT patients (ORR, 50% and 39%). Toxicity was manageable with few severe hematological events, more oftenly occurring after polychemotherapy administration. Particularly, groups of patients taking alkylator-containing regimens (either MP or VBDA/VBMCP) presented relatively higher frequency of drug-related events (46% in each group) than VAD (25%). Global median survival was 50 months (IC95%, 43– 57) and 3-year survival rate was 64% (IC95%, 57–69). In accordance to the greater efficacy, superior 3-year survival rate was achieved when receiving HSCT (85% vs 52%; p<0.001).

Results of this Spanish nation-wide epidemiological study confirmed previous findings in other countries (Kyle, 2003; Conte, 2007). As expected, efficacy varied depending on patient's characteristics and treatment. No safety issues were noted. Survival rate was enhanced by HSCT. Further reports on the outcomes sorted by treatment regimen, as well as potential prognostic factors, will be presented.

López:Celgene: Employment. Baquero:Celgene: Employment.