Prevention of active multiple myeloma (MM) using IL-1 receptor antagonist (IL-1ra) and low-dose dexamethasone (Dex) and monitoring the high sensitivity C-reactive protein (hsCRP)

8105

Background: IL-6 is the central myeloma growth factor and we have shown that abnormal production of IL-1beta in the myeloma microenvironment stimulates the generation of paracrine IL-6. A Phase II trial was completed using IL-1ra, which inhibits paracrine IL-6 production, and low dose Dexamethasone (Dex), which decreases IL-1 levels through myeloma cell apoptosis, in patients with smoldering/indolent MM (SMM/IMM). These patients are at the greatest risk for progression to active MM and most likely to benefit from anti- cytokine therapy. Methods: Patients that had ≥ 10% bone marrow plasma cells and/or an IgG or IgA M-spike ≥ 3 g/dL and did not require immediate chemotherapy were eligible. A total of 47 patients received 100 mg of IL-1ra SQ qd for 6 months unless clinical progression occurred. Responding patients were allowed to continue on therapy with IL-1ra alone. Low dose Dex (20 mg qweek) was added after 6 months of IL-1ra in non-responding patients. The primary endpoint was progression-free survival (PFS). Results: The 47 patients were at high risk for progression to active MM with 98% having ≥ 10% plasma cells, 89% generating IL-1 levels consistent with myeloma (≥ 1.0), and 32% having bone lesions. All 47 patients received IL-1ra initially and 25/47 subsequently received IL-1Ra/Dex. For the group of 47 patients, the median overall progression-free survival was 37.5 months. Three patients achieved a minor response (MR) to Anakinra alone; 5 pts achieved a PR and 4 patients an MR after addition of Dex. Seven patients had a decrease in the plasma cell labeling index (PCLI; a marker of myeloma cell growth) on Anakinra alone which paralleled a decrease in the high sensitivity CRP (a marker of serum IL-6 levels). The median PFS for patients without (n=12) and with (n=35) a ≥ 15% decrease in their baseline hsCRP was 6 months and > 3 yrs, respectively (p=0.002). Conclusions: In SMM/IMM patients at high risk for progression to active myeloma, treatment with IL-1 inhibitors (IL-1ra ± Dex) results in an increased PFS in patients that demonstrate a ≥15% reduction in the baseline CRP compared to those that do not respond.

No significant financial relationships to disclose.

Phase II trial of the oral mTOR inhibitor everolimus (RAD001) for patients with relapsed or refractory lymphoma

8055

Background: mTOR inhibition with intravenous temsirolimus (Wyeth Pharmaceuticals) has been associated with responses in mantle cell lymphoma (J Clin Oncol 23;5347, 2005) as well as other lymphomas (Blood 108 (11) 2483; 2006). This phase II study tested the oral mTOR inhibitor everolimus (RAD001, Novartis Pharmaceuticals) in three simultaneous two-stage phase II lymphoma studies - aggressive (group 1), indolent (group 2), or uncommon (group 3). The goals were to learn the toxicity profile and to assess the anti-tumor response. Planned interim analysis for groups 1 and 3 have been completed and are the subject of this report. Methods: Patients (pts) received 10 mg PO daily for each 28 day cycle (up to 12) and restaged after 2, 6, and 12 cycles. The primary endpoint is the confirmed response rate, including CR, CRu or PR. 12 pts were enrolled in stage 1 of each study. At least 1 success in 12 is required to proceed to stage 2, to a total of 37 pts. Overall, the treatment will be considered promising if 4 or more successes are observed in all 37 pts in each group. Results: The median age of the 12 pts in group 1 was 68.5 yrs (range: 53–80), with a median of 3 (range, 1–15) prior therapies. Four pts had a prior stem cell transplant (SCT). Pts completed a median of 7 (range, 1–12) cycles of therapy. 6 confirmed responses have been achieved (1 CR, 5 PR), meeting the overall criteria for promising results in this study. Common grade 3 adverse events (AEs) include thrombocytopenia (3 pts) and anemia (2 pts). For group 3, the median age was 49 yrs (range, 27–78), with a median of 7 (range, 1–13) prior therapies and 6 pts had a prior SCT. Pts have completed a median of 6.5 cycles (range, 1–11). 5 confirmed responses have been achieved (5 PR), meeting the criteria for this regimen to be considered promising. Of these 5 patients, 3 had HD, 1 T-cell NHL, and 1 had macroglobulinemia. Common grade 3 AEs include anemia (3 pts) and thrombocytopenia (2 pts). No grade 4 AEs were reported. Conclusions: Oral everolimus has activity in a spectrum of lymphomas with acceptable toxicity. The responses observed in both group 1 and group 3 met the criteria to continue accrual. These results provide the rationale for additional studies with this novel class of agents and to integrate mTOR inhibitors into salvage treatment regimens.

No significant financial relationships to disclose.

Absolute lymphocyte count at time of radioimmunotherapy predicted time to progression in patients with relapsed follicular lymphomas

18505

Background: Besides radiation, the immunologic mechanisms of action of 90Y ibritumomab tiuxetan (Zevalin) radioimmunotherapy (RIT) have been attributed to complement mediated lysis and antibody-dependent cellular cytotoxicity (ADCC). We hypothesized that a stronger host immune system prior to Zevalin therapy for relapsed follicular (grade 1&2) lymphomas (FL) would result in an improved time to progression (TTP). As a surrogate marker of host immune status, we studied absolute lymphocyte count (ALC) prior to Zevalin therapy and its impact on TTP in relapsed FL patients. Methods: Between 1996 and 2006, 75 patients with relapsed FL were treated with single agent Zevalin (0.4 mCi/kg, maximum of 32 mCi) at the Mayo Clinic. ALC was obtained from the complete blood cell count prior to RIT. Results: The median age of the cohort was 60 years (range, 29–82 years). 36% (27/75) patients were rituximab refractory. The median TTP in all patients was 6.4 months (range, 1–99+ months). Univariately, ALC as a continuous (HR = 0.448, p < 0.006) or dichotomized [ALC = 1.0 x 109/l (HR = 0.684, p < 0.007)] variable was identified as a prognostic factor for TTP. Superior TTP was observed with an ALC = 1.0 x 109/l (N = 32) compared with an ALC < 1.0 x 109/l (N=43) (median: 12.4 months vs 6.5 months, respectively, p < 0.007). Both groups were balanced in regard to the Follicular Lymphoma International Prognostic Index (FLIPI). ALC, as a continuous (HR = 0.507, p < 0.02) or dichotomized [ALC = 1.0 x 109/l (HR = 0.697, p < 0.01)] variable was identified as an independent prognostic factor for TTP in the multivariate analysis when compared with FLIPI. In the ALC = 1.0 x 109/l group, 14/32 (44%) of FL patients achieved a TTP = 12 months compared to only 7/43 (16%) in the ALC < 1.0 x 109/l group, (p < 0.02). Conclusions: This study supports our hypothesis that a higher ALC, as a marker of immune status of the patient, predicts longer TTP following Zevalin therapy in relapsed FL.

No significant financial relationships to disclose.

Preliminary results from a phase II study of lenalidomide oral monotherapy in relapsed/refractory indolent non-Hodgkin lymphoma

8066

Background: Lenalidomide, an immunomodulatory drug, is approved in the US for treatment of relapsed/refractory multiple myeloma and myelodysplastic syndromes associated with a deletion 5q[31] cytogenetic abnormality. Lenalidomide also has activity in chronic lymphocytic leukemia and cutaneous T-cell lymphoma. This study was designed to assess the safety and efficacy of lenalidomide monotherapy in patients with relapsed/refractory indolent non-Hodgkin's lymphoma (NHL). Methods: Patients with relapsed/refractory indolent NHL with measurable disease after at least 1 prior treatment regimen were eligible. Patients received 25 mg lenalidomide orally once daily on Days 1–21 every 28 days and continued therapy for 52 weeks as tolerated or until disease progression. Response and progression were evaluated using the IWLRC methodology. Results: As of enrollment cut-off, 43 patients received drug and 27 were evaluable for response. The median age was 63 (43–82) and 12 were female. Histology was small lymphocytic lymphoma [SLL] (n=12), follicular center lymphoma grades 1,2 [FCL] (n=12) and nodal marginal B-cell lymphoma [NML] (n=3). Median time from diagnosis to lenalidomide was 4.3 (0.4- 24) years and median number of prior treatment regimens was 3 (1–17). Seven patients (26%) exhibited an objective response (2 complete responses (CR), 1 complete response unconfirmed (CRu) and 4 partial responses (PR)), 9 had stable disease (SD) for a tumor control rate (TCR) of 59% and 11 progressive disease (PD). Responses were produced in each of the indolent histologic subtypes studied: SLL (3/12), FCL (3/12) and NML (1/3). Since most responses develop at ≥ 4 months, additional responses may be seen in early SD patients with longer follow-up. Five patients (12%) exhibited Grade 4 neutropenia, and Grade 3 adverse events were neutropenia (16%) and thrombocytopenia (14%). Conclusion: Lenalidomide oral monotherapy is active with manageable side effects in relapsed/refractory indolent NHL.

[Table: see text]

A practical guide to defining high-risk myeloma for clinical trials, patient counseling and choice of therapy

Clinical outcomes for multiple myeloma (MM) are highly heterogeneous and it is now clear that pivotal genetic events are the primary harbingers of such variation. These findings have broad implications for counseling, choice of therapy and the design and interpretation of clinical investigation. Indeed, as in acute leukemias and non-hodgkins lymphoma, we believe it is no longer acceptable to consider MM a single disease entity. As such, the accurate diagnosis of MM subtypes and the adoption of common criteria for the identification and stratification of MM patients has become critical. Herein, we provide a consensus high-risk definition and offer practical guidelines for the adoption of routine diagnostic testing. Although acknowledging that more refined classifications will continue to be developed, we propose that the definition of high-risk disease (any of the t(4;14), t(14;16), t(14;20), deletion 17q13, aneuploidy or deletion chromosome 13 by metaphase cytogenetics, or plasma cell labeling index >3.0) be adopted. This classification will identify most of the 25% of MM patients for whom current therapies are inadequate and for whom investigational regimens should be vigorously pursued. Conversely, the 75% of patients remaining have more favorable outcomes using existing - albeit non-curative - therapeutic options.

Anti-tumor activity of mTOR inhibitor temsirolimus for relapsed mantle cell lymphoma: A phase II trial in the North Central Cancer Treatment Group

7532

Background: Mantle Cell Lymphoma (MCL) is characterized by t(11;14) resulting in over expression of cyclin D1, a member of the phosphatidylinosital 3-kinase (PI3K) pathway. Temsirolimus is a novel inhibitor of the mammalian target of rapamycin (mTOR) kinase. Previous studies with weekly temsirolimus at a dose of 250mg demonstrated a 38% overall response rate in 35 patients (JCO 23 (23); 5347–56, 2005). Thrombocytopenia was frequently observed and was dose limiting. The current study tested whether low-doses (25mg) of temsirolimus could produce a similar overall response rate (ORR) with less toxicity. Methods: Eligible patients had biopsy proven cyclin D1 positive MCL and had relapsed or were refractory to therapy. Patients received temsirolimus 25mg IV weekly as a single agent. Patients were restaged after 1 cycle (4 doses), after 3 cycles, and every 3 cycles thereafter. Patients with a tumor response after 6 cycles were eligible to continue drug for a total of 12 or 2 cycles after complete remission (CR) and then were observed without maintenance. The goal was to achieve an ORR of at least 20%. Results: Twenty-nine patients were enrolled between March and August 2005. Twenty-two patients have completed therapy. One patient with a major protocol violation on cycle-1 and one ineligible patient were excluded, leaving 27 evaluable patients. The ORR was 41% (11/27), with 1 CR and 10 PRs. Early evaluation of TTP showed a median of 5.5 months (95% CI: 3.3–7.7) and the duration of response for the 11 responders was 6.2 months (95% CI: 3.6 to not yet reached). These results compare favorably with the 6.5 months and 6.9 months, respectively, found in previous trials that used 250 mg. The median dose delivered per month was 80 mg (range, 10–100 mg). Sixteen (59%) of patients required a dose reduction. The median time on treatment was 4.4 months (95% CI, 3.3–7.7). The incidence of grade 3 and 4 thrombocytopenia was 12% and 0%, respectively. One patient experienced grade 5 infection without neutropenia, which was considered unrelated to CCI-779. Conclusions: Single agent CCI-779 at a dose of 25mg has anti-tumor activity in relapsed MCL similar to the 250 mg dose. This study indicates that combinations of temsirolimus with other agents should be feasible.

[Table: see text]

Salvage chemotherapy with rituximab DHAP (RDHAP) for relapsed non-hodgkin lymphoma (NHL): A phase II trial in the North Central Cancer Treatment Group

7574

Background: Patients (pts) with relapsed aggressive NHL are usually treated with intensive platinum-based chemotherapy regimens prior to stem cell transplant (SCT). This study was designed to learn the toxicity and efficacy of adding 4 doses of rituximab to the standard DHAP salvage chemotherapy regimen. Methods: Eligible pts had biopsy-proven relapsed CD20+ NHL and were eligible for platinum-based chemotherapy. Pts were treated with rituximab 375 mg/m2 d1,8,15, and 22 as well as cis-platinum 100 mg/m2 d3, cytosine arabinoside 2 g/m2 IV q 12 hours x two doses d4, dexamethasone 40 mg PO/IV d3–6, and G-CSF d5–14. Pts were restaged after 1 and 2 cycles; responding pts could proceed to SCT or further cycles of DHAP at MD discretion. There was no provision for rituximab maintenance. The goal was to achieve an overall response rate (ORR) of ≥ 75%. Results: Fifty-eight pts were enrolled between 10/29/00 and 6/20/03. The median age was 63 years (range, 43–83). One pt was ineligible because the tumor was CD20-. All 57 eligible pts completed one cycle; 48 pts completed 2 cycles. The ORR was 70% (40/57) with 16 (28%) CR/CRu and 24 (42%) PR. For all 57 pts, the median TTP was 13.1 months (mos) (95% CI: 7.3–18.2) and the median OS 30.5 mos (95% CI: 17.8–52.5). Seventeen pts (30%) proceeded to SCT. The median duration of response (DR), time to progression (TTP) and overall survival (OS) for the SCT pts were 41.6, 42.3, and 43.6 mos, respectively. The median DR, TTP, and OS for the 25 pts who responded to RDHAP but did not proceed to SCT were 12.4, 13.1, and 38.8 mos, respectively. The incidence of grade 3 and 4 thrombocytopenia was 53% and 39%, respectively. The incidence of grade 3 and 4 neutropenia was 11% and 68%, respectively. Six pts (11%) had nephrotoxicity–five grade 3 and two grade 4 (one pt had both) and one pt required dialysis. Conclusions: The addition of rituximab to standard DHAP is safe with similar toxicity profile to DHAP alone. Despite a high ORR, the CR rate and the % pts proceeding to SCT in this cooperative group setting remain low. New agents are needed that can be added to these regimens to increase the effectiveness and reduce toxicity to allow more pts to proceed to SCT.

No significant financial relationships to disclose.

Absolute lymphocyte count prior to rituximab therapy predicts time to progression in patients with follicular grade 1 lymphoma

7586

Background: The immunologic mechanisms of action of rituximab have been described as complement mediated lysis, vaccine like effect, antibody-dependent cellular cytotoxicity (ADCC) and the cellular microenvironment. We hypothesized that in the treatment of follicular grade 1 lymphoma (FL), the presence of a stronger host immune status prior to rituximab therapy would result in a prolonged time to progression (TTP). As a surrogate marker for immune status, we evaluated the absolute lymphocyte count (ALC) prior to rituximab treatment. Methods: Between 1996 and 2002, 1,104 consecutive FL patients were evaluated at Mayo Clinic Rochester. Of these patients, we retrospectively analyzed a group of all FL patients who received rituximab (375 mg/m2 once a week for four weeks) alone at any time during their lymphoma treatment at the Mayo Clinic (n=79). The primary end-point was to assess the impact of ALC just prior to rituximab therapy on TTP for FL. Results: The median age of the cohort was 56.6 years (range: 25–98 years). The median follow-up was 12.5 months (range: 1–76 months). An ALC count of ≥ 890 cells/μL prior to rituximab therapy predicted a longer TTP compared with an ALC < 890 cells/μl (25 months versus 8 months, respectively, p < 0.0124). A higher complete response rate was observed in the ALC ≥ 890 cells/μL group compared with the ALC < 890 cells/μL group [15/40 (38%) vs 5/39 (13%), p < 0.035]. The groups were balanced regarding the Follicular Lymphoma International Prognostic Index (FLIPI) (p = 0.794). Multivariate analysis demonstrated ALC ≥ 890 cells/μL prior to rituximab therapy as an independent prognostic factor for TTP when compared to hemoglobin, LDH, and Ann Arbor stage. The ALC was independent of the FLIPI in multivariate analysis. Conclusions: This data supports the hypothesis that a higher lymphocyte count, as a marker of the immune status of the patient, predicts for a longer TTP following rituximab therapy.

No significant financial relationships to disclose.

Preliminary results from two phase II studies of lenalidomide monotherapy in relapsed/refractory non-Hodgkin’s Lymphoma

17569

Background: Lenalidomide is an immunomodulatory drug of the IMiD class that has activity in multiple myeloma, myelodysplastic syndromes and chronic lymphocytic leukemia. We report preliminary results of two Phase II studies assessing the safety and efficacy of lenalidomide monotherapy in subjects with relapsed/refractory indolent or aggressive non-Hodgkin’s lymphoma (NHL). Methods: Subjects with indolent (study NHL-001) or aggressive (study NHL-002) relapsed/refractory NHL following ≥ 1 prior treatment regimen with measurable disease are eligible. Subjects receive 25 mg lenalidomide orally once daily on Days 1–21 every 28 days and continue therapy for 52 weeks as tolerated until disease progression. Response and progression are evaluated using cross sectional imaging by the NCI criteria. Results: 10 subjects (2 indolent (I), 8 aggressive (A)) of a planned 80 (40 in each study) have enrolled thus far. Median age is 66 (45–80) and 7 subjects are female. Indolent histology is follicular center lymphoma grade 1, 2 (n = 2) and aggressive histology diffuse large cell lymphoma (n = 7) and follicular center lymphoma grade 3 (n = 1). Median time from diagnosis to lenalidomide monotherapy is 2.9 years (1.1–10) and median number of prior treatment regimens per subject is 3 (1–6). Median duration of follow-up is 2 months. Of eight subjects (2 I, 6 A) evaluable for response at two months, three demonstrated a decrease in their tumor burden by 72% (I), 68% (A) and 52% (A), two subjects (2 A) exhibited stable disease and three subjects (1 I, 2 A) had disease progression. Six of the ten subjects (2 I, 4 A) demonstrated no Grade 3 or 4 adverse events. Grade 3 or 4 hematological adverse events (neutropenia, thrombocytopenia) occurred in four subjects including one febrile neutropenia and one of these four subjects also exhibited Grade 3 cellulitis. No tumor flare or tumor lysis has been observed to date. Conclusions: Preliminary data of lenalidomide monotherapy in relapsed and refractory NHL are encouraging.

[Table: see text]

Alterations in cell proliferation and apoptosis in human colon cancers with microsatellite instability

10022

Background: Patients with colon cancers displaying high frequency microsatellite instability (MSI-H) are reported to have a favorable prognosis compared to microsatellite stable (MSS) tumors. However, prognostic factors underlying this observation are poorly understood. We studied apoptotic and proliferative indices and their relationship to MSI status, clinicopathological features, and patient survival rates. Methods: Archival Dukes’ stage B2 (n=83) and C (n=246) primary colon adenocarcinomas from patients enrolled in five 5-fluorouracil-based adjuvant therapy trials were analyzed for MSI using a PCR-based assay (MSI-H: ≥30% of loci with instability), and expression of hMLH1, hMSH2 and p53 proteins by immunostaining. Apoptosis was analyzed by the TUNEL assay and the proliferative index (PI: S phase + G2M) and DNA ploidy by flow cytometry. Correlations between markers and associations with overall survival (OS) censored at 8 yrs were sought. Results: MSI-H (n=58.18%) tumors were more likely proximal, diploid, high grade, p53 negative (vs. MSS/MSI-L; all p<0.0001), and from women (p=0.002). Of 58 MSH-H cases tested, 54 showed loss of hMLH1 (n=50) or hMSH2 (n=4) proteins. Median proliferative index (PI) [12.6 vs. 17.4; p=0.0002] was reduced in MSI-H versus MSS/MSI-L tumors. Lower PI was associated with diploidy (p<0.0001) and negative p53 expression (p=0.003). Apoptotic indices (AIs) were increased in MSI-H cancers (vs. MSS/MSI-L, p=0.082), as was the AI/PI ratio (p=0.0065). Interestingly, AI (p=0.02) and AI/PI (p<0.0001) were significantly increased in diploid versus nondiploid tumors, and after removal of MSI-H cases, relationships held for PI and AI/PI with ploidy. Better OS was related to MSI-H (p=0.032), loss of hMLH1 or hMSH2 (p=0.024), diploidy (p=0.0015), and lower PI (p=0.078), but not AI, AI/PI, nor p53 (adjusting for stage, grade, treatment and stratifying by study). Conclusions: MSI-H tumors are characterized by reduced proliferative indices and a higher ratio of apoptosis to proliferation, reflecting slower tumor growth rates compared to MSS/MSI-L tumors. These features may contribute to their better survival. Lower PI and increased AI/PI are also features of diploid MSS cancers.

[Table: see text]

CD45 expression by bone marrow plasma cells in multiple myeloma: clinical and biological correlations

Multiple myeloma (MM) is characterized by accumulation of clonal plasma cells (PCs). CD45, a key regulator of antigen-mediated signaling and activation in lymphocytes, is present in early stages of PCs development. We studied CD45 expression on MM PCs by flow cytometry, correlating it to important biological disease characteristics. Additionally, we examined the expression of various adhesion molecules on PCs. A total of 75 patients with untreated MM (29), relapsed MM (17), smoldering MM (12), and monoclonal gammopathy of undetermined significance (MGUS) (17) were studied. The proportion of PCs expressing CD45 was higher among those with early disease (MGUS or smoldering MM) compared to those with advanced disease (new or relapsed MM) (43 vs 22%; P=0.005). Among those with advanced disease, patients with bone lesions had a lower percentage of CD45-positive (CD45+) PCs; 14 vs 34% (P=0.02). Patients with high-grade angiogenesis had a lower percentage of CD45+ PCs; 13 vs 31% (P=0.03). The median overall survival for the CD45+ group (>20% PCs positive) was 39 vs 18 months for the CD45-negative (CD45-) group (P=0.07). The expression of CD138, CD56 and CD54 were higher among the CD45- PCs. This study demonstrates important biological correlates of CD45 expression on myeloma cells.

Single agent dexamethasone for pre-stem cell transplant induction therapy for multiple myeloma

Given the survival advantage, high-dose therapy (HDT) remains the standard of care for patients with multiple myeloma eligible for the procedure. For those undergoing HDT, initial therapy aimed at reducing tumor burden is given prior to stem cell harvest. Various regimens, mostly variations of VAD (vincristine, doxorubicin, dexamethasone), are used for induction therapy. We retrospectively evaluated if single agent dexamethasone would be an effective induction therapy, given that it is the most active drug in these combinations. A total of 35 patients who received induction therapy with dexamethasone alone were compared to a similar group of 72 patients who received VAD as the initial therapy. We found a 63% response rate with dexamethasone compared to 74% with VAD (P=0.25). Including minimal responses, the overall response rate for Dex and VAD was 74 and 86%, respectively (P=0.13). The overall and complete response rates to transplant, respectively, were 97 and 26% for the dexamethasone group and 100 and 39% for the VAD group; P=0.33 and 0.18. No significant differences were observed in the progression-free and overall survival at 1 year post transplant. Single agent dexamethasone appears to be an effective alternative to VAD for induction therapy prior to HDT in myeloma.

High-dose therapy and autologous stem cell transplantation for multiple myeloma poorly responsive to initial therapy

Autologous stem cell transplant (SCT) improves survival in multiple myeloma (MM) and remains the standard of care for eligible patients. Nearly a third of patients with newly diagnosed MM fail initial therapy aimed at reducing tumor burden preceding SCT (primary refractory). It is unclear if an initial response is important for successful SCT. We evaluated our experience with SCT in 50 patients with primary refractory MM and compared it to 101 patients with chemosensitive disease receiving SCT. The study cohort had a median age of 56 years (range 29-72) consisting of 87 males (58%). A total of 46 patients (92%) in the refractory group and 100 (99%) in the chemosensitive group had a response to transplant (50% or greater reduction in the M-protein). In all, 10 refractory patients (20%) and 35 (35%) in the chemosensitive group achieved a CR (P=0.06). The 1-year estimated progression-free survival from the time of transplant for the refractory group was 70% compared to 83% for the chemosensitive group (P=0.65). The lack of response to initial induction therapy does not appear to preclude a good response to SCT. We recommend that patients with primary refractory MM be offered early SCT.

A phase I study of 153Sm-EDTMP with fixed high-dose melphalan as a peripheral blood stem cell conditioning regimen in patients with multiple myeloma

Despite response rates of 30% after high-dose chemotherapy with autologous hematopoietic stem cell transplant, patients with multiple myeloma are not cured. 153Samarium ethylenediaminetetramethylenephosphonate (153Sm-EDTMP; Quadramet) is a short-range, beta-emitting therapeutic radiopharmaceutical with avid skeletal uptake. In total, 12 patients were treated with escalating doses of 153Sm-EDTMP (N=3/group; 6, 12, 19.8, and 30 mCi/kg) and a fixed dose of melphalan (200 mg/m(2)). No dose limiting toxicity was seen. To better standardize the marrow compartment radiation dose, the study was modified such that an additional six patients were treated at a targeted absorbed radiation dose to the red marrow of 40 Gy based on a trace labeled infusion 1 week prior to the therapy. Despite rapid elimination of unbound radiopharmaceutical via kidneys and bladder, no episodes of nephrotoxicity, hemorrhagic cystitis, or delayed radiation nephritis were observed with a median follow-up of 31 months (range 8.5-44). Median times to ANC>0.5 and platelet >20 x 10(6)/l were 12 and 11 days, respectively, with no graft failures. Overall response rate was 94% including seven very good partial responses and five complete responses. Addition of 153Sm EDTMP to melphalan conditioning appears to be safe, well-tolerated and worthy of further study.