Polymerase chain reaction-based detection of minimal residual disease in multiple myeloma patients receiving allogeneic stem cell transplantation

BACKGROUND AND OBJECTIVES

Recent advances in the treatment of multiple myeloma (MM) include use of high-dose chemoradiotherapy followed by allografting. Although allografting with bone marrow (BM) or peripheral blood stem cells (PBSC) seems to improve clinical outcome and lengthen survival, only about 50% of patients reach stringently defined complete remission (CR), and most subsequently relapse. We assessed the clinical relevance of minimal residual disease (MRD) in 14 MM patients in CR after allografting with PBSC (6 patients) or BM (8 patients).

DESIGN AND METHODS

Among the 30 out of 72 MM patients in our Institute who achieved CR after allografting, 14 had a molecular marker suitable for allo-specific polymerase chain reaction (PCR) analysis. Stringent molecular monitoring was done using clonal markers based upon rearranged immunoglobulin heavy-chain genes. Molecular remission (MCR) was defined as two consecutive negative PCR results.

RESULTS

Seven of 14 (50%) molecularly monitored patients, achieved MCR and did not relapse after a median molecular follow-up of 60 months (range 36-120). Median time to obtain first PCR negativity was 12 (BM group) and 6 months (PBSC group), respectively. Of the seven patients (50%) who never achieved MCR, one relapsed.

INTERPRETATION AND CONCLUSIONS

In conclusion, 50% of the MM patients in CR studied by us also achieved stringently-defined MCR. MCR was associated with a very low rate of clinical relapse.

Use of peripheral blood stem cells for autologous transplantation in acute myeloid leukemia patients allows faster engraftment and equivalent disease-free survival compared with bone marrow cells

We compared the feasibility and efficacy of autologous bone marrow (ABMT) and peripheral blood progenitor cell transplantation (PBSCT) performed after an identical induction/consolidation in adults with acute myeloid leukemia (AML). From January 1993 to June 1996 91 consecutive AML patients were enrolled in a program consisting of anthracycline-based induction and high-dose cytarabine consolidation (NOVIA). Until May 1994 ABMT was performed; from June 1994, if PBSC collection was adequate, PBSCT was performed. Out of 88 evaluable patients, 73 obtained a complete remission (CR) and 15 were resistant. Allogeneic bone marrow transplantation was performed in 16 patients. Forty-four (50%) were given autologous stem cell transplantation. ABMT was performed in 21 cases; twenty-nine patients were given G-CSF mobilization after NOVIA administration. An adequate number of PBSC was obtained in 23/29 (79%) cases, which were then re-infused. Median times to both neutrophil and platelet recovery from transplant were significantly shorter for the PBSC group (17 vs 36 days to 500 PMN/microl, P < 0.01; 20 vs 150 days to 20000 platelets/microl, P < 0.02; 37 vs 279 days to 50000 platelets/microl, P < 0.03), as were days of hospitalization after the reinfusion (18 vs 33, P < 0.03) and median days to transfusion independence. Toxicity was not significant in either group. After a minimum follow-up for live patients of 24 months (longer than the mean time for relapse observed for the PBSC series - 14 months) the percentage of relapses was similar: 11 of 21 (52.4%) and 12 of 23 (52.1%) in the ABMT and PBSC groups, respectively. Our results indicate that autologous PBSC transplantation, performed after an intensive chemotherapy regimen, is not inferior to ABMT in terms of disease-free survival and allows faster recovery times and reduced need for transfusion support.

Induction of a functional vitamin D receptor in all-trans-retinoic acid-induced monocytic differentiation of M2-type leukemic blast cells

Different types of acute myeloid leukemia blast cells were induced to differentiate in vitro with all-trans-retinoic acid (ATRA) and vitamin D3 (VD). M0/M1 leukemic cells are not sensitive to differentiating agents, whereas M3 leukemic cells are induced to undergo granulocytic differentiation after ATRA treatment but are not sensitive to VD. M2 leukemic blast cells behave differently because they undergo monocytic differentiation with both the differentiation inducers. To gain some insight into the maturation of M2-type leukemic cells, we studied the molecular mechanisms underlying monocytic differentiation induced by ATRA and VD in spontaneous M2 blast cells as well as in Kasumi-1 cells (an acute myeloid leukemia M2-type cell line). Our results indicate that ATRA as well as VD efficiently increases the nuclear abundance of VD receptor (VDR) and promotes monocytic differentiation. VDR is functionally active in ATRA-treated Kasumi-1 cells because it efficiently heterodimerizes with retinoid X receptor, binds to a DR3-type vitamin D-responsive element, and activates the transcription of a vitamin D-responsive element-regulated reporter gene. Consistent with these findings, VD-responsive genes are induced by ATRA treatment of Kasumi-1 cells, suggesting that the genetic program underlying monocytic differentiation is activated. The molecular mechanism by which ATRA increases the nuclear abundance of a functional VDR is still unknown, but our data clearly indicate that the M2 leukemic cell context is only permissive of monocytic differentiation.

Evaluation of immunotoxins containing single-chain ribosome-inactivating proteins and an anti-CD22 monoclonal antibody (OM124): in vitro and in vivo studies

Immunotoxins were prepared with three ribosome-inactivating proteins (RIP), momordin, pokeweed antiviral protein from seeds (PAP-S) and saporin-S6, linked to the anti-CD22 monoclonal antibody OM124. These immunotoxins inhibited protein synthesis by CD22-expressing cell lines Daudi, EHM, BJAB, Raji and BM21 with IC50 (concentration causing 50% inhibition) ranging from < 5 x 10(-15) to 7.6 x 10(-11) M as RIP, and IC90 (concentration causing 90% inhibition) ranging from 5 x 10(-14) to 5 x 10(-8)M, with no effect on a CD22-negative HL60 cell line at the highest concentration tested (5 x 10[-8] M). Apoptosis was induced in sensitive cells. The formation of bone marrow colonies was inhibited by no more than 40% by the immunotoxins at concentrations up to 10(-9) M. Treatment with the immunotoxins, alone or in combination, significantly extended the survival time of mice bearing transplanted Daudi cells. A treatment with cyclophosphamide and OM124/saporin immunotoxin was particularly effective in SCID mice transplanted with a low number of cells (3 x 10[-6]), when 60% of the animals remained tumour-free.

Newer approaches in treating chronic myelogenous leukemia

Allogeneic bone marrow transplantation (BMT) is a useful approach for treating patients with chronic myelogenous leukemia (CML). In patients who lack a suitable donor, various approaches to utilize the patient's own hematopoietic stem cells obtained from bone marrow and/or peripheral blood have been developed. Preferential recovery of normal human hematopoietic progenitors over CML clone in long-term bone marrow culture (LTBMC) has been observed for a long time. LTBMC initiated in tissue culture (TC) flasks to that in "Lifecell" bags, which are gas-permeable plastic bags in which feeder-layer cells cannot adhere, has been investigated for several years. In our laboratory, cells were incubated in the presence of various growth factors to develop improved methods for stem cell expansion. Sustained hematopoietic stem cell growth in the absence of a feeder layer in plastic gas-permeable bags has been observed. Growth of marrow from patients with CML is being investigated extensively. Combining effective drugs to decrease the Philadelphia (Ph) clone prior to bone marrow harvest and the use of cultured bone marrow may provide a useful method for treating patients with CML. Results of various international studies are also discussed below.

Newer approaches in treating chronic myelogenous leukemia

We evaluated the recovery of human hematopoietic progenitors in long-term bone marrow culture (LTBMC) initiated in tissue culture (TC) flasks to that in "Lifecell" bags, which are gas-permeable plastic bags in which feeder-layer cells cannot adhere. Cells were incubated in presence of IL-1 and IL-3. Our experiments reveal sustained hematopoietic stem cell growth in the absence of a feeder layer in plastic gas-permeable bags. Evaluations of marrow from patients with chronic myelogenous leukemia suggests enrichment of normal hematopoietic precursors. Combining effective drugs to decrease Ph(+) clone prior to bone marrow harvest and use of cultured bone marrow may provide a useful method for treating patients with chronic myelogenous leukemia.

Treatment of patients with relapsed and resistant non-Hodgkin's lymphoma using total body irradiation, etoposide, and cyclophosphamide and autologous bone marrow transplantation

PURPOSE

Patients with non-Hodgkin's lymphoma (NHL) who do not achieve a complete response (CR) after induction chemotherapy or who relapse after achieving a CR are rarely cured of their disease by the usual salvage therapy. Success of high-dose cytotoxic therapy with an autologous bone marrow transplant (AuBMT) is limited. We describe the results of a prospective single-institution study using a new conditioning regimen for patients with relapsed or resistant NHL who underwent AuBMT.

PATIENTS AND METHODS

Forty-four patients were reinduced with cytotoxic therapy and then evaluated for response. All patients received the conditioning regimen of hyperfractionated total body irradiation (TBI), etoposide (VP-16), and cyclophosphamide (CTX) followed by autologous bone marrow reinfusion.

RESULTS

The disease-free survival (DFS) rate was 57% with a median follow-up of 42+ months. The only variable significantly associated with DFS was the patient's remission status at AuBMT. Patients who underwent AuBMT in CR had a DFS of 80%, whereas patients who underwent AuBMT in partial response (PR) or with progressive disease (PD) had a DFS of 60% and 11%, respectively (P = .002). The major toxicity was hemorrhage at the site of bulky disease, especially in patients with residual mediastinal and/or pulmonary disease.

CONCLUSION

Planned reinduction cytotoxic therapy followed by TBI, VP-16, and CTX with AuBMT is an effective treatment for patients with relapsed and resistant NHL.