Relapsed Multiple Myeloma Patients Research Articles

Phase I Study of Bortezomib and 153Sm-Lexidronam Combination for Refractory and Relapsed Multiple Myeloma.

Background: Multiple myeloma (MM) is a highly radiosensitive B-cell malignancy and radiation therapy is an effective treatment for these patients. Recent preclinical studies have demonstrated that the bone-seeking radionuclide, Samarium Sm153 lexidronam (Sam) in combination with the proteasome inhibitor, bortezomib (Velcade [Vel]), can synergistically inhibit proliferation of myeloma cell lines in vitro and reduce MM growth in mice bearing murine MM without significant myelotoxicity. These results provide the basis for a new targeted therapeutic approach for refractory and relapsed MM patients involving combining Vel with Sam to improve the anti-MM effects of these agents without increasing their toxicity.Aims: The primary objective of this dose escalation Phase I study is to determine safety and tolerability as well as the response rate as determined by Blade criteria of Vel + Sam treatment for patients with relapsed or refractory MM.Methods: MM patients who had failed ≥2 prior treatments will be enrolled on this Phase I dose-escalation trial which involves six cohorts with three patients each. Previous treatment with Vel is allowed. Dose escalations in parallel arms are as follows:A complete treatment cycle is 8 weeks, and patients are to receive a maximum of 4 cycles. Vel is given on days 1, 4, 8 and 11 followed by a 45-day rest period. Sam is administered only on day 3. The cycle is repeated on Day 57 if disease is stable or improved and platelets and neutrophils recover to at least Grade 1 toxicity (may be delayed for up to four weeks). Dose limiting toxicity (DLT) is defined as cycle 1 Grade 4 hematologic or Grade ≥3 non-hematologic toxicity.Results: Eighteen patients have been enrolled to date in cohorts 1 through 5. Three patients have been treated in cohorts 1, 2, 4, and 5, and 6 patients have been entered in cohort 3. Fifteen patients are evaluable for response and the other 3 patients have not yet completed a treatment cycle. Of 15 evaluable patients, 3 patients including one Velcade-refractory patient have shown responses [immunofixation+ complete response {IF+ CR} (n=2) and minor response (n=1)], 3 have stable disease, and 9 patients showed progressive disease. One Velcade-refractory patient with progressive disease initially showed a transient IF+ CR. Two patients developed transient Grade 4 thrombocytopenia. One of these episodes occurred during Cycle 1 in a patient in cohort 3; and, as a result, cohort 3 has been expanded to a total of 6 patients. Four patients showed transient Grade 3 neutropenia. Only two patients showed treatment emergent neuropathy one of which resolved while on study. To date, seven patients remain on study and one patient has completed 4 cycles of therapy.Conclusions: Early results from this dose escalation Phase I trial evaluating the combination of Vel and Sam are encouraging and demonstrate responses in relapsed and refractory MM patients. The trial continues to enroll subjects. Updated results from this study will be presented at the meeting.Arm 1Arm 2SamVelSamVelCohort 10.25 mCi/kg1.0 mg/m2Cohort 40.25 mCi/kg1.3 mg/m2Cohort 20.5 mCi/kg1.0 mg/m2Cohort 50.5 mCi/kg1.3 mg/m2Cohort 31.0 mCi/kg1.0 mg/m2Cohort 61.0 mCi/kg1.3 mg/m2

Velcade as Retreatment of Multiple Myeloma Patients Previously Responsive to Velcade.

Velcade (bortezomib, PS 341) represents a novel class of anti-cancer drugs that, according to the randomized phase 3 trial (APEX) including 669 patients with relapsed multiple myeloma (MM), resulted more effective than high-dose dexamethasone as demonstrated by a significant improvement in response rate (43% vs 18%), median time to progression (6.2 vs 3.4 months) and 1-year survival rate (80% vs 67%, respectively). Its use in addition to dexamethasone in patients who had suboptimal responses to velcade alone has been associated with an improvement in responses without prohibitive toxicity, suggesting that the combination of these two drugs can overcome drug resistance. This agent is highly effective on extramedullary plasmacytomas and usually induces a very rapid response (after 1 or 2 cycles), independently of the previous therapies used. To evaluate the possibility of re-inducing a response in relapsed patients previously treated with velcade, we re-treated 3 patients with the same drug at 1.3 mg/m2 administered on days 1, 4, 8 and 11 of a 21-day treatment cycle for 8 cycles and dexamethasone 20 mg on the day of and on the day after each velcade dose. The patients (2 females and 1 man) previously treated with velcade as single agent after 47, 54 and 93 months, respectively, from diagnosis and after more than two lines of previous therapy, obtained a very good response without a complete disappearance of the monoclonal component. They were thereafter observed and re-treated with the same drug plus dexamethasone for a relapse documented after 7, 13 and 23 months, respectively. Velcade was well tolerated and the toxicity acceptable, without additional adverse events compared to the first administration. No patient experienced a herpes zoster reactivation and all side effects were typically reversible and disappeared upon drug suspension. Response was very rapid with a >50% decrease of the monoclonal component after 3, 4 and 5 cycles, respectively. It can be hypothesized that velcade, which offers great promise to overcome resistance to conventional chemotherapy, may not be susceptible to the most common drug resistance mechanisms. Based on the chronic nature of MM, drugs with documented efficacy, absence of cumulative toxicities and which do not develop resistance following repeated treatment are required. The responses observed in our relapsed MM patients who received velcade for the second time are encouraging. A longer follow-up and a greater number of patients will conclusively confirm the true efficacy of velcade as re-treatment drug. Updated results on a larger number of treated patients will be available at the time of presentation.

PAD Is a Highly Effective Regimen for the Treatment of Patients with Relapsed Refractory Multiple Myeloma.

Background and aim of the study:Bortezomib (Velcade®) is a first-in-class potent and reversible proteasome inhibitor that has been approved for the treatment of relapsed and/or refractory multiple myeloma (MM). With single agent bortezomib, complete (CR) and partial (PR) response rates have been reported in 27% of patients with relapsed refractory (Richardson 2003), and in 38% of patients with relapsed MM (Richardson 2005). Addition of dexamethasone (dex) to bortezomib can increase the response rates (Jagannath, 2005), and a synergistic anti-myeloma effect has been described when bortezomib is combined with cytotoxic drugs like anthracyclins and melphalan (Ma, 2003). With the combination of PAD (bortezomib, adriamycin and dex) a 95% CR+PR rate in untreated myeloma patients has been reported (Oakervee, 2005), but data on the effectiveness of PAD in the relapsed, refractory setting are currently lacking.Patients and Treatment:We have studied the anti-myeloma effect of PAD in 8 unselected relapsed refractory MM patients (M/F:6/2; mean age 61 y, range:50–75). The mean time since diagnosis was 6 years (range:2–11). Previous treatment consisted of a median of 6 treatment lines including autologous (n = 6) and allogeneic (n = 2) transplantation, various forms of combination chemotherapy (n = 8) including anthracyclins (n = 7), pulse dose dex (n = 7), thalidomide −/+ dex (n = 7), bortezomib (n = 8) without (n = 3) or with dex (n = 5). PAD was administered as previously published (Oakervee, 2005), but with 12 days of dex administration also during during the odd cycles.Results:A median of 4 cycles of PAD were administered (range: 2–6). The CR+ PR rate was 88% according to the EBMT criteria: one patient achieved a CR (IF+), one a VGPR, and 5 patients a PR. One patient had a limited amount of paraprotein secretion but multiple extramedullary plasmacytomas. After 2 cycles of PAD she had > 50% reduction in tumormass on PET-CT imaging. On average, the best response occurred already after 2 cycles of PAD. 4/8 patients relapsed after a mean interval of 5 months and 3 patients are still in remission at + 5 months. Two patients developed septicaemia with one toxic death. Hematological grade III/IV toxicities included: neutropenia (4/8), and thrombocytopenia (4/8). Neuropathy pre-existed in 4/8 patients and was not aggravated with appropriated dose reductions of bortezomib.Conclusion:Using a combination of bortezomib, adriamycin and dexamethasone (PAD), we could obtain at least a PR in 8/8 unselected highly refractory myeloma patients who had, amongst many other agents, previously been exposed to bortezomib and/or adriamycin and/or dexamethasone. Major toxicities of PAD were hematological with one toxic death because of septicaemia. We believe that our observation warrants further studies of the PAD regimen in relapsed MM.

Phase I study of bortezomib and 153Sm-lexidronam combination for refractory and relapsed multiple myeloma

7614 Background: Multiple myeloma (MM) is a highly radiosensitive B-cell malignancy and radiation therapy has been an effective treatment for these patients. Recent preclinical studies have demonstrated that the bone-seeking radionuclide, Samarium Sm153 lexidronam (Sam) in combination with the proteasome inhibitor, bortezomib (Vel), can synergistically inhibit proliferation of myeloma cell lines in vitro and reduce MM growth in mice bearing human MM without significant myelotoxicity. These results provide the basis for a new therapeutic approach of combining Vel and Sam to overcome resistance and to minimize nontumor tissue toxicity among refractory and relapsed MM patients. Methods: The primary objective of this Phase I study is to determine the response rate and tolerability of Vel + Sam combination in patients with relapsed or refractory MM. Patients will be enrolled on this Phase I dose-escalation trial which involves six cohorts. Previous treatment with Vel is permissible. Dose escalation in parallel arms is as follows: A complete treatment cycle is 8 weeks. Vel is given on days 1, 4, 8 and 11 followed by a 45-day rest period. Sam is administered on day 4. The cycle is repeated on Day 57 if disease is stable or improved and platelets and neutrophils recover to at least grade 1 toxicity. DLT is defined as cycle 1 grade 4 hematologic or grade ≥3 non-hematologic toxicity. Results: Cohorts 1 and 4 have been enrolled (3 patients per cohort). One cycle of treatment has been completed thus far. No significant toxicity has been observed except a transient fever in one patient. There have been no dose limiting toxicities to date. The first six patients will be evaluated for response within the next two weeks. Conclusions: The trial will continue to enroll patients in cohorts 2 and 5. Updated results from the trial will be presented at the meeting. [Table: see text] [Table: see text]

Preclinical and clinical development of the proteasome inhibitor bortezomib in cancer treatment

The proteasome is a ubiquitous enzyme complex that plays a critical role in the degradation of many proteins involved in cell cycle regulation, apoptosis and angiogenesis. Since these pathways are fundamental for cell survival and proliferation, particularly in cancer cells, the inhibition of proteasome is an attractive potential anticancer therapy. The present review will focus on the proteasome inhibitor bortezomib (Velcade, formerly PS-341; Millennium Pharmaceuticals, Inc., Cambridge, MA, USA). Bortezomib is an extremely potent and selective proteasome inhibitor that shows strong activity in in vitro and in vivo laboratory studies against many solid and hematologic tumor types. Moreover, bortezomib, mainly by inhibition of the NF-kappaB pathway, has a chemosensitizing effect when administered together with other antitumoral drugs. Based on these results, bortezomib entered clinical phase I trials, alone or in combination with chemotherapy, that showed good tolerance at doses that achieved a desired degree of proteasome inhibition. Phase II studies showed high response rates in refractory multiple myeloma patients, which led to the accelerated approval of bortezomib by the U.S. Food and Drug Administration (FDA) and the European Medicines Agency (EMEA) for this indication. A phase III trial comparing bortezomib with dexamethasone in refractory/ relapsed multiple myeloma patients had to be halted due to a survival advantage in the bortezomib arm. Additional studies are focusing on the potential benefit of bortezomib in newly diagnosed multiple myeloma patients. In other solid and hematological malignancies, phase II studies with bortezomib alone or in combination with other agents are ongoing. Encouraging results, particularly in lung cancer and lymphoma, have been observed. The critical molecules or genes responsible for tumor sensitivity to bortezomib continue to be evaluated using novel technologies.

Use of simple hematological, biochemical and clinical parameters to monitor response of multiple myeloma patients on high dose thalidomide therapy

Evidence of increased bone marrow vascularity in multiple myeloma (MM) has led to the use of anti-angiogenic drugs especially thalidomide in relapsed or refractory patients. Currently, parameters such as serum/ urine electrophoresis for M (monoclonal) proteins, bone marrow biopsy with touch preparation and b2 microglobulin are routinely used to assess response to therapy. These investigations are expensive, invasive and require high technical setup. To correlate simple and routine hematological and biochemical parameters with the key marker of disease i.e. M proteins. This is an open label, uncontrolled, single-arm study. Twenty nine refractory or relapsed multiple myeloma patients of both sexes (M=20, F=9) with age ranging between 35-72 years were initiated on 200 mg/day of thalidomide with fortnightly increments of 200 mg to a maximum tolerated dose not exceeding 800 mg/day. All hematological and biochemical parameters were monitored at monthly intervals for one year. Correlation analysis was performed between hemoglobin (Hb), total leukocyte count (TLC), absolute neutrophil count (ANC), platelet count (PC), total proteins (TP), serum albumin and serum globulin on one hand and M protein levels on the other using Pearsons Correlation test by SPSS version 7.5. Hb, TLC, ANC, PC and serum albumin levels showed a significant negative correlation with M proteins. A highly significant positive correlation existed between M proteins on one hand and TP and globulin levels on the other. Dryness of skin indicated positive response to therapy. These correlations were found to be significant at the end of one month of therapy in all the above-mentioned parameters except in TLC where it was significant after 2 months of thalidomide therapy. Results suggest that sustained efficacy of thalidomide therapy may be amenable to monitoring by these simple, inexpensive and easily available investigations after ascertaining an initial response by M protein and marrow plasmacytosis as these parameters closely follow M protein levels. However more studies are required to further substantiate these findings.

Combined thalidomide and cyclophosphamide treatment for refractory or relapsed multiple myeloma patients: a prospective phase II study

Thalidomide is an effective agent for patients with refractory multiple myeloma (MM) with a response rate of 30-40% at doses of 200-800 mg but with considerable side effects. We questioned whether lower doses of thalidomide in combination with a daily dose of cyclophosphamide might be an effective regimen with fewer side effects. We included 38 patients with relapsed or refractory MM. The median doses of thalidomide and cyclophosphamide were 100 and 95 mg/day, respectively. Side effects were observed in all patients, with neurotoxicity as the most troublesome. With a median follow-up of 14 months 84% of the patients responded, including 64% partial responses. The median time of progression-free survival was 30 months and the median overall survival time was 20 months. In conclusion, the results demonstrate that the combination of low-dose thalidomide with a daily dose of cyclophosphamide is an effective regimen with a high overall response rate and manageable side effects.

Outcome after Second Autologous Stem Cell Transplantation as Salvage Therapy in Patients with Relapsed Multiple Myeloma.

Background: Single autologous stem cell transplant (ASCT) is considered the standard of care for younger multiple myeloma (MM) patients (pts). However, it is not curative and virtually all patients will ultimately relapse. The role of a second ASCT as salvage therapy is unclear.Method: Retrospective review of all MM pts who received a 2nd ASCT as salvage therapy at Princess Margaret Hospital.Results: Between March 1992 and August 2004, 28 MM pts received a second ASCT for relapsed MM at our institution. Median age was 57 years (range 39–69) at second transplant. 17 pts were male.Immunoglobulin subtype included IgG (16), IgA (8), light chain (1), nonsecretory (2) and IgM(1). Median initial albumin was 42g/l (27–48). In 15 patients in whom cytogenetic studies were available, 2 were positive for the 13q deletion.Transplant conditioning regimen for first transplant was melphalan (MEL) + TBI +/− etoposide (E) in 6, MEL alone in 15 and other regimens in 7 pts. 2nd ASCT conditioning consisted of MEL + TBI +/− E in 2, MEL alone in 25 and BU+CY in 1. Median CD34 counts were 10.96x106/L and 4.85x106/L for 1st and 2nd ASCT respectively.The median time from diagnosis to first transplant was 9 months (2–74). The median time to relapse after the first transplant was 29 months (6–85), with a median interval between transplants of 39 months (6–99). The median time to progression after the second transplant was 13 months (5–56).No transplant-related deaths occurred.At median follow-up after 2nd ASCT of 15 months (1–60), 20 (71%) pts are alive. Twelve pts (43% of all pts) are free of disease progression. The 5-year actuarial progression-free survival (PFS) and overall survival (OS) was 47% and 32%, respectively. Long term progression-free status based on the progression-free interval after 1st transplant is summarized in the following table:IntervalTotal number of ptsNumber of progression-free pts≤ 12 months10 (0%)12–24 months93 (33%)≤ 24 months189 (50%)Conclusions:1.2nd ASCT is a feasible and safe salvage therapy in relapsed MM patients;2.2nd ASCT is effective in providing prolonged remission over one year;3.2nd ASCT is most effective in patients whose time to progression after 1st ASCT exceeds 24 months.

Donor lymphocyte infusions for multiple myeloma: clinical results and novel perspectives.

Donor lymphocyte infusions (DLIs) provide effective therapy for patients with various hematological malignancies who have relapsed after allogeneic hematopoietic stem cell transplantation (HSCT). In patients with multiple myeloma (MM), DLIs can induce response rates of 40-52%. DLIs were employed as treatment for MM relapse or as prophylaxis for relapse in MM patients undergoing allo-HSCT. The clinically most relevant treatment-related morbidity with DLIs is the occurrence of graft-versus-host disease (GVHD). Secondly, graft failure and the immune escape of extramedullary plasmocytoma have been reported. The fact that previous clinical reports have documented graft-versus-myeloma (GVM) activity without GVHD suggests that at least two distinct immunocompetent cell populations mediating GVHD and/or GVM may exist. Further characterization of the effector cells such as T cells and/or NK cells and their targets may help to clarify the immune response that mediates the GVM effect. This review considers the results of clinical approaches with DLI for MM, with emphasis on strategies to prevent GVHD while preserving the GVM effect. Furthermore, currently investigated molecular antigenic targets for the GVM effect such as MM-specific idiotypic determinant of immunoglobulin variable regions, several PRAME epitopes and antigenic structures encoded by cancer germline-specific genes as candidates for immunotherapy trials are discussed.

A clinical and pharmacological study of arsenic trioxide in advanced multiple myeloma patients.

We previously showed that arsenic trioxide (ATO) and melarsoprol may inhibit the growth of multiple myeloma (MM) cells in vitro and in vivo. We report here the administration of arsenic derivatives in 12 relapsing or refractory secretory MM patients. A total of 10 patients received ATO (eight in a continuous schedule, two discontinuously) and two received melarsoprol. The melarsoprol arm was prematurely closed due to toxicity. In the ATO arm, median duration of treatment was 38 days (9-54). Hepatic toxicity was grade 3 and 2 in one and eight patients, respectively. Other toxicities included neuropathy (n=2, grade 2), encephalitis (n=1, grade 3) and leuconeutropenia (n=4, grade 3). At 2 weeks after treatment initiation, mean serum concentration of arsenic was 1.11+/-0.16 micromol/l. No complete or partial remission was observed. A minor response (25-49% reduction of M protein in serum) and a stabilization of the M-protein level were observed in three and four patients, respectively. After ATO discontinuation, these responses were of short duration in all cases. ATO as a single agent did not produce any significant response in advanced MM patients despite sufficient arsenic exposure. Strategies to improve biodistribution, pharmacokinetic and efficacy of the drug as well as treatment combinations are needed.

Bortezomib in multiple myeloma: treatment approach and outcomes

Because multiple myeloma (MM) remains incurable, new therapeutic approaches are needed. Proteasome inhibition represents a new therapeutic strategy with the potential to inhibit multiple pathogenic pathways in MM. In phase I trials, the novel proteasome inhibitor bortezomib demonstrated encouraging activity in patients with advanced MM. In the SUMMIT phase II trial, 202 heavily pre-treated patients with relapsed and refractory MM received bortezomib 1.3 mg/m 2 twice weekly for 2 weeks, followed by a 1-week rest. The overall response rate, defined as complete + partial + minimal responses (CR + PR + MR), was 35%, with CR or near-CR in 10% of patients. Median duration of response was 12 months and median duration of survival 16 months for all patients. Adverse effects included manageable gastrointestinal symptoms, thrombocytopaenia, and peripheral neuropathy. Thrombocytopaenia and neuropathy were generally reversible and occurred mainly in patients who already had these toxicities at time of enrollment. In the CREST phase II trial, 54 patients with relapsed or refractory MM after first-line therapy were randomised to receive bortezomib 1.0 mg or 1.3 mg/m 2, twice weekly for 2 weeks, followed by a 1-week rest. Overall response rates were 33% at the 1.0 mg dose and 50% at the 1.3 mg dose. Toxicities were similar to those seen in SUMMIT, with nausea, diarrhoea and peripheral neuropathy occurring more frequently at the higher dose level. In conclusion, the results of the SUMMIT and CREST trials show that bortezomib is highly active in patients with relapsed and refractory MM. A large phase III trial comparing bortezomib with dexamethasone in relapsed MM patients was recently stopped after a pre-specified interim analysis showed a statistically significant improvement in time to disease progression for patients receiving bortezomib. Studies testing bortezomib as front-line therapy are ongoing.

The combination of thalidomide, cyclophosphamide and dexamethasone (ThaCyDex) is feasible and can be an option for relapsed/refractory multiple myeloma.

Thalidomide has recently proven to be a useful drug for treatment of refractory and relapsed multiple myeloma patients, up to 35% of whom achieve remission. However, little is known about the potential additive or synergistic effect upon its association with other drugs with proven efficacy in MM. The present pilot study was designed to evaluate the toxicity and response rate of the association of thalidomide, cyclophosphamide and dexamethasone (ThaCyDex) in 22 refractory or relapsed MM patients. The protocol scheduled the administration of thalidomide at escalating doses (200 to 800 mg/day), daily oral cyclophosphamide (CTX) (50 mg/day) and pulsed dexamethasone (40 mg/day, four days every three weeks). Adverse effects were moderate (grade <or=2) with only two patients in whom treatment was withdrawn due to neuropathy and severe somnolence. Infections were recorded in six patients, four requiring hospitalization for intravenous antibiotic therapy. No cases of thrombocytopenia grade >or=2 were noted. Other side effects included grade <or=2 constipation (29%), somnolence (35%) or dizziness (12%). In addition, one case of meralgia paresthetica and one with a deep venous thrombosis were noted. Two cases displayed hyperglycemia and myopathy attributed to dexamethasone, which was solved upon changing to prednisone. With a median follow-up of 12 months, 17 patients were evaluable for response; 13 (77%) responded to the therapy, including nine cases (53%) with a >50% M-component reduction (two of them with a complete remission). Only two responders have already progressed, with a projected event free survival of 51% at 12 months. Seven patients have died due to disease progression (n=5), sudden death (n=1) and infection (n=1). This study shows that ThaCyDex is a feasible and promising therapeutic approach for patients with relapsed/refractory MM.

Therapy with thalidomide in refractory multiple myeloma patients - the revival of an old drug.

We have treated 17 refractory or relapsed multiple myeloma patients resistant to chemotherapy with thalidomide at a dose of 200-800 mg/day. Eleven patients responded, five of whom had a very good partial response (> 75% decline in M protein) and another five exhibited a partial response (> 50% decline in M protein). Except for one patient, treatment was well tolerated with only mild side-effects. Thalidomide should be included in the therapeutic options for refractory myeloma.

Intravenous Melphalan and Dexamethasone Followed by Lymphoblastoid Alpha Interferon in Higher Risk Multiple Myeloma Patients

Intermittent courses of melphalan and prednisone is still the standard chemotherapy for the initial treatment of multiple myeloma (MM) in patients who cannot undergo high-dose chemotherapy/radiotherapy with either allogeneic or autologous stem cell transplantation. However, the absorption of the drug from the gastrointestinal tract is highly variable from patient to patient and therefore, different plasma levels of the drug are reached in the blood of individual MM patients. In order to overcome this limitation we decided to use intermediate dose (15-30 mg/m2, day 1) intravenous melphalan in resistant or relapsing MM patients as well as in untreated patients not eligible for a more aggressive protocol. Moreover, considering the good results obtained by other investigators using dexamethasone alone or associated with interferon in the treatment of resistant or relapsing MM patients, dexamethasone (40 mg total dose, day 1) and the lymphoblastoid alpha interferon (3 MU, 3 times a week x 3 weeks, from day 8 to day 26 of each course) were added to intravenous melphalan. Courses were repeated every 5 weeks for a total of 6 cycles. We treated 62 MM patients obtaining a response (defined as reduction > 25% of the initial monoclonal component value associated with disappearance of the clinical symptoms) in 38 out 62 evaluable patients (61%) and stable disease (defined as a decrease of < 25% in the base-line serum monoclonal component level with disappearance of all symptoms present at diagnosis) in 9 (14.5%) more patients. The overall median response duration was 14 months and the overall median survival duration (from the time of inclusion in this protocol) for the 62 patients entered into the study was 34 months. No severe (Grade 3-4 of the WHO) hematological as well as non hematological toxicities were observed. This lack of severe toxicity allowed us to administer the drugs on an outpatient basis. In conclusion, the overall response and the low grade of toxicity in this category of patients are encouraging and suggest that this protocol is both effective and safe treatment for high risk MM patients.

RT-PCR Amplicons in the Plasma of Multiple Myeloma Patients - Clinical Relevance and Molecular Pathology

The occurrence of RNA (RT-PCR amplicons) in the plasma of 70 patients was quantified: 65 patients with multiple myeloma (MM), 3 with Waldenstrom's macroglobulinemia (WM), 2 with monoclonal gammopathy of undetermined significance (MGUS), and 50 from healthy controls. A 713nt amplicon occurred in 16/18 MM patients in relapse, 5/8 untreated patients, 2/3 WM patients and 1/2 MGUS plasmas. None of the initial specimens from 37 patients in remission nor the 50 healthy controls was positive. Homology between 4 sequenced 713nt amplicons was >99.7% and matched (99.6%) a 704nt sequence of the flanking region of the peroxisome proliferator activator receptor gene, located on chromosome 22q11.2. A 255mer within the 713nt amplicon had a 90.2% homology with an AluSc consensus sequence. The occurrence of RNA amplicons seemed to serve as accurate surrogate markers for active disease in MM that provide new insights to the molecular pathogenesis of the disease.

Bcl-2 overexpression is associated with resistance to paclitaxel, but not gemcitabine, in multiple myeloma cells.

Multiple myeloma (MM) is an incurable disease despite an initial response-rate of >60% with conventional or high-dose chemotherapy using glucocorticosteroids (i.e. dexamethasone), or alkylating agents (i.e. melphalan). Although these agents are capable of inducing complete remission (CR) in >50% of MM patients, resistance develops rapidly, in >90% of patients, within 2 years of treatment. Therefore, there is a need for new drugs for the treatment of relapsing and refractory MM patients. Gemcitabine (GEM) is a pyrimidine analog that blocks DNA synthesis, whereas, paclitaxel (TAX) is a mitotic spindle poison that promotes microtubular aggregation. Since it appears that these two drugs have different cellular targets, we examined the effect of each drug individually for several parameters and for possible synergy. We studied the cytotoxic effect of TAX and GEM on MM cells expressing varying levels of the antiapoptotic protein bcl-2, which is overexpressed in the majority of myeloma cell from MM patients. We found that both drugs are cytotoxic by inducing apoptosis, however, the extent of apoptosis with TAX, but not with GEM was dependent on the levels of bcl-2 expression. We further investigated the effect of TAX and GEM on the cell cycle distribution and on the levels of bcl-2. The results indicate that the two drugs have different modes of action with respect to each parameter tested. TAX induced arrest of the cells in the G2/M phase of the cell cycle, regardless of bcl-2 levels, however, apoptosis was induced in mitotic cells expressing relatively low levels of bcl-2. In contrast, GEM caused apoptosis of cells in the S-phase, regardless of level of bcl-2 expression. A major difference between TAX and GEM was in their effects on the levels of bcl-2. Whereas, TAX induced an early downregulation of bcl-2 (only in the cells with relatively low levels of bcl-2), treatment with GEM did not affect bcl-2 levels. The effects of TAX on both the cell cycle and bcl-2 were detected very early (4-8 h) and preceded the onset of apoptosis. GEM and TAX act synergistically, at low doses (IC50 of 0.5 microM for GEM and 0.025 microM for TAX), to effectively kill bcl-2 overexpressing cells that are resistant to higher doses (0.25 microM) of TAX alone. Therefore, we have initiated a phase II clinical trial of TAX and GEM for MM patients refractory to current therapy.