Next generation flow for minimally-invasive blood characterization of MGUS and multiple myeloma at diagnosis based on circulating tumor plasma cells (CTPC)

Here, we investigated for the first time the frequency and number of circulating tumor plasma cells (CTPC) in peripheral blood (PB) of newly diagnosed patients with localized and systemic plasma cell neoplasms (PCN) using next-generation flow cytometry (NGF) and correlated our findings with the distinct diagnostic and prognostic categories of the disease. Overall, 508 samples from 264 newly diagnosed PCN patients, were studied. CTPC were detected in PB of all active multiple myeloma (MM; 100%), and smoldering MM (SMM) patients (100%), and in more than half (59%) monoclonal gammopathy of undetermined significance (MGUS) cases (p <0.0001); in contrast, CTPC were present in a small fraction of solitary plasmacytoma patients (18%). Higher numbers of CTPC in PB were associated with higher levels of BM infiltration and more adverse prognostic features, together with shorter time to progression from MGUS to MM (p <0.0001) and a shorter survival in MM patients with active disease requiring treatment (p ≤ 0.03). In summary, the presence of CTPC in PB as assessed by NGF at diagnosis, emerges as a hallmark of disseminated PCN, higher numbers of PB CTPC being strongly associated with a malignant disease behavior and a poorer outcome of both MGUS and MM.

Increased conventional chemotherapy does not improve survival in multiple myeloma: long-term results of two PETHEMA trials including 914 patients

BACKGROUND

Melphalan and prednisone (MP) has been the standard treatment for multiple myeloma (MM) for the last 30 years. Combination chemotherapy at conventional doses has not shown a significant prolongation of survival when compared to MP. There are few data comparing conventional chemotherapy at standard doses with conventional treatment at higher doses. We present the long-term outcome of 914 patients from two randomized trials comparing three different dose intensity regimens.

METHODS

From 1 January, 1985 to 31 December, 1989, 487 patients were randomized between MP (melphalan 9 mg/m(2) p.o. and prednisone 60 mg/m(2) days 1-4) and alternating VCMP (vincristine 1 mg i.v. on day 1, cyclophosphamide 500 mg/m(2) i.v. on day 1, melphalan 6 mg/m(2) p.o. on days 1-4, and prednisone 60 mg/m(2) on days 1-4) and VBAP (vincristine 1 mg i.v. on day 1, BCNU and doxorubicin 30 mg/m(2) i.v. each on day 1, and prednisone 60 mg/m(2) on days 1-4). From 1 January, 1990 to 31 May, 1994, 427 patients were randomized between VCMP/VBAP at the above detailed doses (VCMP/VBAP 'SD') and the same regimen increasing the doses of cyclophosphamide and doxorubicin from 500 to 1200 mg/m(2) and from 30 to 50 mg/m(2), respectively (VCMP/VBAP 'HD').

RESULTS

Increasing dose intensity produced a significantly higher partial response rate (31% vs 45% vs 51% for MP, VCMP/VBAP 'SD', and VCMP/VBAP 'HD', respectively; P < 0.01). However, a significantly early death rate was observed in the HD arm (7.7, 7.5 and 12.1% for MP, VCMP/VBAP 'SD', and VCMP/VBAP 'HD', respectively; P = 0.05). Median duration of response (20 vs 18 vs 19 months for MP, VCMP/VBAP 'SD', and VCMP/VBAP 'HD', respectively; P = NS) and median survival (25 vs 31 vs 29 months for MP, VCMP/VBAP 'SD', and VCMP/VBAP 'HD', respectively; P = NS) were similar in the three groups. MP produced a higher degree of thrombocytopenia than combination chemotherapy at standard (P = 0.002) or high dose (P = 0.01), this leading to a significantly higher dose reduction in the MP arm (P < 0.001 and P = 0.003 for VCMP/VBAP 'SD' and VCMP/VBAP 'HD', respectively).

CONCLUSION

In these trials the response rate significantly correlated with the regimen intensity. However, no significant differences in response duration and survival were found. This highlights the limited role of conventional chemotherapy in MM and the need for further trials, aimed at determining the impact of new treatment approaches such as high-dose therapy/autotransplantation.