Search

8048 Background: Preclinical studies from our laboratory have demonstrated that ruxolitinib (RUX) in combination with lenalidomide (LEN) and dexamethasone shows marked anti-myeloma effects both in vitro and in vivo. Furthermore, MUC1 is responsible for LEN resistance in MM cells, and RUX blocks its expression in MM cells. Thus, RUX may restore sensitivity to LEN. Therefore, a phase 1 trial was conducted to determine the safety and efficacy of RUX in combination with LEN and methylprednisolone (MP) for relapsed/refractory (RR) MM patients (pts) who had previously been treated with LEN/steroids and a proteasome inhibitor (PI) and showed progressive disease at study entry. Methods: A traditional 3+3 dose escalation design was used to enroll subjects in four cohorts with planned total enrollment to be 49 pts. Subjects received RUX twice daily continuously, LEN daily on d1-21 of a 28-d cycle and MP orally every other day. In DL0, pts received RUX 5 mg, LEN 5 mg, and MP 40 mg. In DL+1 and +2, both doses of LEN and MP remained unchanged and RUX was escalated to 10 and 15 mg, respectively. DL+3 escalated LEN to 10 mg with MP unchanged and RUX at 15 mg. Primary endpoints were safety, clinical benefit rate (CBR) and overall response rate (ORR). Results: As of September 1, 2018, 36 pts were enrolled, and 32 were evaluable for efficacy. The median age was 66 years (range, 46-81), and 21 (58%) were male. Pts received a median of 6 prior treatments including LEN and steroids to which they were all refractory and a proteasome inhibitor. No DLTs occurred, and DL+3 was expanded. Among evaluable pts, the CBR and ORR were 47% and 41%, respectively (1 CR, 2 VGPR, 10 PR and 2 MR), and 14 and 3 pts showed SD and PD. All 15 responding pts were refractory to LEN. G3 AEs included anemia (17%), neutropenia (14%), sepsis (14%), lymphocytopenia (11%), thrombocytopenia (11%), and pneumonia (11%). Most common SAEs included sepsis (14%) and pneumonia (11%). Conclusions: This Ph 1 trial demonstrates for the first time that a JAK inhibitor, RUX, can overcome refractoriness to LEN and steroids for RR MM pts. These promising results are leading to expansion of the current clinical trial to 78 pts, and represents a novel therapeutic approach for treating MM. Clinical trial information: NCT03110822.

8005Background: Preclinical studies from our laboratory have demonstrated that ruxolitinib (RUX) in combination with lenalidomide (LEN) and dexamethasone shows marked anti-myeloma effects both in vitro and in vivo. Furthermore, MUC1 is responsible for LEN resistance in MM cells, and RUX blocks its expression in MM cells. Thus, RUX may restore sensitivity to LEN. Therefore, a phase 1 trial was conducted to determine the safety and efficacy of RUX in combination with LEN and methylprednisolone (MP) for relapsed/refractory (RR)MM patients (pts) who had previously been treated with LEN/steroids and a PI and showed progressive disease at study entry. Methods: A traditional 3+3 dose escalation design was used to enroll subjects in four cohorts with planned total enrollment to be 28 pts. Subjects received RUX twice daily continuously, LEN daily on d1-21 of a 28-d cycle and MP orally every other day. In DL0, pts received RUX 5 mg, LEN 5 mg, and MP 40 mg. In DL+1 and +2, both doses of LEN and MP remained unchanged...

e20012Background: Pomalidomide (POM) is a third–generation immunomodulatory drug shown to be safe and effective for the treatment of relapsed/refractory multiple myeloma (RRMM) patients (pts) previ...

8013 Background: The proteasome inhibitor (PI) ixazomib (Ixz) is the first orally administered PI approved for treating multiple myeloma (MM). It has shown clinical activity as a single agent and when used in other combinations. In this phase 1/2 trial, we evaluated Ixz as a replacement therapy for bortezomib or carfilzomib for MM patients who were refractory to a bortezomib- or carfilzomib-containing combination regimen. Methods: This was a phase 1/2, intra-patient, multicenter, open-label trial evaluating the replacement of ixazomib for bortezomib or carfilzomib for MM patients who were refractory in combination with the other agents that the patients had received and failed. Patients received Ixz on days 1, 8 and 15 on a 28-day schedule and the other drugs were administered using the same doses and schedules as they were receiving during their prior regimen. If the Ixz maximum tolerated dose (MTD) for a particular combination regimen was previously determined, then patients were enrolled directly into Phase 2 (PhII). If not, MTD was determined during the Phase 1 (PhI) portion of the trial. Results: To date, a total of 40 patients have been enrolled; 37 patients (21 were enrolled in PhI and 16 in PhII) had completed at least one cycle of this treatment. Patients received a median of 5 prior treatments (range, 1-22). The median follow-up time for all patients was 1.6 months (range, 0.1-10.7 months), whereas that of PhII was 2.2 months (range, 0.2-10.7 months). There was no clinical benefit (CBR; 0%) nor any overall response rate (ORR; 0%) for patients receiving Ixz 3 mg (PhI). Nine patients (43%) showed stable disease (SD) while 12 (57%) exhibited disease progression (PD). In PhII (4mg Ixz) portion of the trial, ORR and CBR were both 18.7% with 16 (43.2%) patients showing SD, and 18 (48.6%) patients displaying PD. Common ≥ Gr3 adverse events were anemia (11%), thrombocytopenia (5.4%), hyponatremia (5.4%), dehydration (5.4%) and neutropenia (2.7%). Conclusions: Replacement of bortezomib or carfilzomib with Ixz infrequently leads to responses among RRMM patient who have progressed while on proteasome inhibitor -containing combination regimens. Clinical trial information: NCT02206425.

e19528 Background: Pomalidomide (POM) is a third –generation immunomodulatory drug shown to be safe and effective for the treatment of relapsed/refractory multiple myeloma (RRMM) for patients (pts) previously treated with bortezomib and lenalidomide (LEN) and in combination with dexamethasone it has been shown to overcome resistance in RRMM. In this phase 2 trial, we are evaluating the efficacy, safety and tolerability of POM as a replacement therapy for LEN for pts who have progressed receiving a LEN combination regimen. Methods: This is a phase 2, multicenter, open-label and non-randomized study. Pts who have failed a combination regimen containing LEN were treated with POM along with all of the other drugs previously used in the regimen. POM administered orally (dose is determined based on the previous regimen) on days 1-21 of a 28-day cycle, whereas other drugs are administered using the same schedule(s), dose(s) and drug combination as the last LEN-containing regimen that the patient received and failed. The planned enrollment on the study will be 45 pts. Results: To date, a total of 29 pts have been enrolled, 25 pts are evaluable and 12 pts have discontinued treatment. Of the evaluable pts, 9 (36%) and 16 (64%) received 3mg and 4mg of POM, respectively. The median age of all pts was 72 years (range, 52-81), and 17 (68%) were males. Pts have received a median of 3 prior treatments (range, 1-7). The median follow-up time for all pts is 3.1 months (range, 0.2-8.1). Amongst evaluable pts, 5 (23.8%) pts achieved at least a minimal response, 10 (47.6%) pts showed stable disease while 6 (28.6%) pts exhibited disease progression. At the time of data cutoff, only 17 pts have completed more than 1 full cycle of treatment; and, thus, the overall response and clinical benefit rates are fairly low (14.3% and 23.8%, respectively) but expected to improve with further follow up. The median PFS for the cohort was 7.6 months. Common ≥ Gr3 adverse events were neutropenia (8%), hypomania (4%) and leukopenia (4%). Conclusions: We show thatPOM appears to be promising replacement therapy for LEN in RRMM pts who have progressed within receiving a LEN combination regimen.

8591 Background: Treatment with POM and DEX has shown efficacy in RRMM patients (pts), even in those refractory to lenalidomide (LEN). In this phase (Ph) 1/2 trial, we investigated the POM-DEX-PLD ...

e19586^ Background: The POM-DEX combination is an effective treatment for RRMM patients (pts), even those refractory to lenalidomide (LEN). We investigated the combination of POM-DEX-PLD using a mo...

8599 Background: Recent data has shown that single-agent CFZ can produce responses among MM pts refractory to previous treatment regimens including those containing BTZ. We conducted an intrapatient phase I/II trial investigating the safety and efficacy of CFZ as a replacement for BTZ in BTZEcontaining regimens to which pts have progressed. Methods: Eligible pts progressed while receiving their most recent BTZEcontaining regimen after at least 4 doses of BTZ at ≥1.0 mg/m² in ≤4 weeks per cycle. CFZ replaced BTZ in each regimen via intravenous administration over 30 min on days 1, 2, 8, 9, 15, and 16 of each cycle. Treatment continued using the same dose(s) and schedule(s) of each drug administered in the BTZEcontaining regimen. CFZ doses were escalated on each of the first 4 cycles from 20 to 27, 36, and 45 mg/m² or until a maximum tolerated dose (MTD) was reached for that regimen. Results: Of 37 enrolled pts, 33 were evaluable for efficacy and 37 for safety. Pts received a median of 4 prior treatments (range, 1-23) and 2 different BTZ-containing regimens (range, 1-13). Pts were treated with CFZ and a variety of different combinations of agents, including: bendamustine, clarithromycin, cyclophosphamide, dexamethasone, melphalan, methylprednisolone, pegylated liposomal doxorubicin, thalidomide, lenalidomide, and ascorbic acid. Pts have completed a median of 3 cycles with 12 pts going on to maintenance. One of 14 combinations, CFZ + ascorbic acid + cyclophosphamide, has reached a MTD at 45 mg/m2. Clinical benefit was seen in 23 (70%) evaluable pts (complete response = 6%; very good partial response = 18%; partial response = 21%; minor response = 24%) with another 18% showing stable disease. The median time to progression is 8.8 mo. (95% CI: 6.4-11.1 mo.) with 21 pts progressing overall and 9 progressing on study treatment. The most common ≥ G3 adverse events were lymphopenia (35% of pts), thrombocytopenia (19%), neutropenia (11%), and anemia (8%). Conclusions: These results suggest that replacement of BTZ with CFZ in a BTZ-containing combination regimen to which a MM patient is failing often leads to responses and is well-tolerated. Clinical trial information: NCT01365559.

e20044 Background: Multiple myeloma (MM) patients (pts) have shown a higher risk of developing other cancers, although the type, time course, and relationship to MM treatment of these cancers are less clear. In this study, we determined the risk of specific skin cancer (CA) types among MM patients and its relationship to onset of MM and treatment. Methods: MM pts and unrelated age, sex, and race-matched companions (controls) seen at a MM clinic were enrolled in a retrospective cohort study. Information regarding baseline characteristics of MM and history of skin CA was obtained from medical records. Overall skin CA prevalence and types were compared between groups; among MM patients, the occurrence of skin CA was analyzed relative to date of diagnosis and treatment regimens, with stratification according to treatment duration. Results: We enrolled 205 MM pts and 201 controls with 27.3% and 14.9% demonstrating skin CA, respectively (p < 0.001). Specific types of skin CA included 60 and 37 basal cell carcinomas (BCC), 50 and 17 squamous cell carcinomas (SCC), and 9 and 5 melanomas in the MM pts and controls, respectively. The standardized incidence ratios (SIR) were SCC: 2.88 (p< 0.001), BCC: 1.59 (p

8598 Background: POM is a newer IMiD immunomodulatory compound with high in vitro potency that has shown promise in combination with DEX as an effective treatment option for R/R MM patients (pts), even those refractory to bortezomib and lenalidomide (LEN). We conducted a phase I/II trial investigating the safety and efficacy of POM in combination with IV DEX and PLD using a modified dose and longer 28-day schedule in R/R MM pts. Methods: Phase I pts had progressive MM at the time of enrollment that was R/R to at least one anti-MM regimen. Phase II pts had to be refractory to LEN (singe-agent or in combination) demonstrated by progressive disease while receiving LEN or relapse within 8 weeks of its last dose. During phase I, POM was administered orally at 2, 3, or 4 mg daily in 3 successive cohorts of 3 pts each on days 1-21 of each 28-day cycle. DEX was administered IV at 40 mg over 30 min and PLD was administered at 5 mg/m2as an IV infusion over 30-90 min on days 1, 4, 8, and 11 of each cycle. POM doses were escalated until maximum tolerated dose (MTD) was reached. Once MTD was reached, all subsequent pts were enrolled at that dose. Results: To date, 27 pts have been enrolled, with 18 evaluable for efficacy and 19 for safety. Pts received a median of 5 prior treatments (range, 1-18) with a median of 1 prior PLD regimens (range, 0-2). Pts have completed a median of 1 cycle (range: 0-8) with a median of 1.4 months of follow up (range: 0-7.1). No DLTs were seen during phase I, which established the MTD at 4 mg. Phase II has enrolled 16 pts at 4 mg so far. Clinical benefit was seen in 7 (39%) of evaluable pts (partial response = 22%; minor response = 17%) with another 44% showing stable disease. Common ≥ G3 adverse events included leukopenia (32% of pts), neutropenia (32%), lymphopenia (26%), and hyponatremia (16%). Neutropenia at ≥ G3 occurred in more than half of patients on the phase II trial (4 mg POM). Conclusions: The combination of pomalidomide with dexamethasone and PLD on a 28-day cycle shows efficacy for R/R MM pts. However, because of excessive ≥ G3 neutropenia, POM is being reduced to 3 mg for newly enrolled patients. Clinical trial information: NCT01541332.

e18558 Background: PAN, a potent histone deacetylase inhibitor, significantly inhibits the growth of MM cells in vitro and enhances the cytotoxicity of standard chemotherapy. Studies with our SCID-hu MM models show an increased inhibition of MM cell growth when PAN was combined with MEL compared to treatment with either drug alone. These preclinical studies provided the rationale for evaluating the combination of oral MEL with oral PAN for the treatment of MM patients with R/R disease. Methods: This was a Phase 1/2, open-label, dose‑escalation study to treat R/R MM patients initially using oral PAN every Monday, Wednesday and Fridayin combination with oral MEL (0.05 mg/kg) on days 1-5 of a 28‑day cycle. Results: Thirty-seven patients were enrolled into the Phase 1 portion of this study. The median number of prior regimens received were 4 (range, 1-17) with 22 patients previously treated with MEL. Following amendments to dose and schedule because of toxicity including cytopenias and fatigue, PAN and MEL were both administered only on days 1, 3 and 5 of a 28-day cycle. The maximum tolerated dose for this combination was defined as PAN at 20 mg and MEL at 0.05 mg/kg both administered on only days 1, 3 and 5. Overall, 4 patients (11%) showed objective responses to this combination with 1 complete (3%) and 3 partial (8%) responses and only occurred among patients receiving PAN throughout the cycle. An additional 18 (49%) patients had stable disease while 15 (41%) progressed while on study. Eighteen patients experienced grade 3 or 4 adverse events (AEs) with 6 of these meeting the definition of a dose-limiting toxicity. These AEs included reversible thrombocytopenia (n=11), reversible neutropenia (n=10), reversible worsening anemia (n=3), and one case each of a forearm rash, fatigue/weakness, pneumonia, hypokalemia and hyponatremia. Three more patients who are not yet evaluable have been enrolled into the Phase 2 portion to complete the planned 40 patients on the trial. Conclusions: The combination of intermittent PAN & low-dose oral MEL shows modest activity in heavily pretreated patients with R/R MM. Continuous doses of PAN with MEL yielded better efficacy but this treatment schedule was not tolerable.

e18549 Background: B cell maturation antigen (BCMA) is a receptor whose expression increases during B-cell development and is found on malignant cells from multiple myeloma (MM) patients; however, it has not been identified in human serum. Methods: Bone marrow (BM) aspirates and peripheral blood were obtained from patients with MM, monoclonal gammopathy of undetermined significance (MGUS) and healthy control subjects following informed consent (Western IRB BIO 001). Serum was isolated and analyzed with a BCMA enzyme‑linked immunosorbent assay. Values represent the mean of triplicate experiments. BM mononuclear cells (MCs) were isolated using density‑gradient centrifugation and cultured for 72 h in RPMI1640 supplemented with 10% fetal bovine serum. Our human MM xenograft (LAGκ-2)was grown in SCID mice and treated with bortezomib (BORT) with cyclophosphamide (CY); tumor volume and BCMA levels were determined. Statistical significance of differences observed was determined using a Student’s t test and analysis was determined using GraphPad prism software. Results: We showed that the supernatants of cultured BMMCs from MM patients had high concentrations of BCMA (median = 2,250 pg/ml) whereas normal subjects showed minimal amounts (56 ng/ml; P < 0.0001). The serum BCMA levels from newly diagnosed MM patients (n = 51) had much higher levels (13.74 ng/ml) than among controls (n = 40; median 2.58 ng/ml; P < 0.0001) and MGUS subjects (n = 26; median 5.40 ng/ml; P = 0.005). Notably, protein levels were much higher among patients with relapsed or refractory (R/R) disease (n = 79; median 20.02 ng/ml) compared to those with responsive (> partial response) disease (n = 80; median 4.14 ng/ml; P = 0.0038). Following treatment, patients with responsive disease showed decreases in BCMA levels whereas those with R/R disease showed increases. Following treatment with BORT and CY, we also showed a marked decrease in tumor volume and serum human BCMA levels in mice bearing the LAGκ-2 xenograft whereas untreated animals showed marked increases in tumor size and serum BCMA. Conclusions: This is the first report identifying serum BCMA in any human disease and suggests that these levels may be a novel biomarker for monitoring disease status and therapeutic response of MM patients.

8070 Background: Novel, effective treatment combinations are needed for pts with relapsed/refractory multiple myeloma (MM). Bendamustine is a unique akylating agent active in MM. Bortezomib is approved for treatment of MM and is effective in combination with alkylators (eg, melphalan and cyclophosphamide). This open-label, phase I/II study assessed the efficacy/safety of bendamustine plus bortezomib in relapsed/refractory MM. Methods: Pts ≥18 years, with measurable, relapsed/refractory MM received escalating doses of bendamustine IV at 50, 70, or 90 mg/m2 (days 1 and 4) plus bortezomib 1.0 mg/m2 (days 1, 4, 8, and 11) for up to 8 28-day cycles. Dose-limiting toxicity (DLT) was assessed after cycle 1. A standard 3+3 approach was used to determine the maximum tolerated dose (MTD). The MTD cohort was expanded to 40 pts. Endpoints included response, duration of response (DOR), time to progression (TTP), and safety. Results: 38 pts (median age 67; range 43-89) received study drug and were included in the analy...

8134 Background: PLD and bortezomib (BORT) are FDA-approved for MM patients who have received one prior therapy. We have previously demonstrated in laboratory studies that lower doses of PLD administered more frequently are better tolerated than higher doses given less often. The combination of BORT and dexamethasone (DEX) is effective for previously untreated MM patients. Prior studies by our group have shown that intravenous administration of DEX 40 mg, BORT 1.0 mg/m2 and PLD 5 mg/m2 (DVD) on days 1, 4, 8, and 11 of a 28-day cycle is effective for relapsed/refractory MM patients and well tolerated. Methods: We conducted a single-arm multi-center phase II study for previously untreated MM patients to evaluate the DVD regimen. Patients were treated to a maximum response plus two additional cycles or completed a maximum of eight cycles of therapy without disease progression. Results: Thirty-five patients were enrolled with a median age of 65 years (range, 42-82 years). Thirty and 33 patients are currently ...

e19523 Background: Preclinical data show that PLD and bortezomib demonstrate synergistic anti-MM effects. Clinical trials have demonstrated the efficacy of this combination for MM patients (pts) as well as its superiority to bortezomib alone. In vivo studies have shown that more frequent administration of low-dose PLD produces enhanced anti-MM effects with better tolerability compared to weekly standard doses of PLD. Thus, a low dose PLD dosing schedule was evaluated in combination with bortezomib and dexamethasone for pts with R/R MM. Methods: This retrospective analysis sought to evaluate the DVD regimen for pts with R/R MM. Twenty pts who had received and failed at least one prior treatment for MM were studied. Treatment consisted of intravenous administration of 40 mg dexamethasone, 1.0 mg/m2 bortezomib and 5.0 mg/m2 PLD on days 1, 4, 8 and 11 of a 28-day cycle. Pts ranged in age from 43–81 years (median 65), and had received between 1–14 prior therapies (median 5). Baseline disease stage was: 6 (I), 7 (II), and 7 (III). Elevated serum creatinine levels at baseline were found in 30% of patients. Results: The objective response rate (ORR) was 50%, which included 1 complete response (5%), 1 very good partial response (5%), 4 partial responses (20%), and 4 minimal responses (20%). Sixteen pts had previously received bortezomib-containing regimens and 6 (38%) responded. Among the entire cohort, the duration of response was 2+-19+ months (mo) (median 7 mo). Six pts had stable disease (30%) lasting between 5–9 mo (median 9 mo). Progression-free survival was 1+-19+ mo (median 8 mo). The regimen was well tolerated with a single mild case of transient hand and foot syndrome and 10 pts developed grade 1 or 2 peripheral neuropathy. One pt discontinued the regimen due to an adverse event (AE; 5%). The median overall survival was 17 mo (range 1+-33+ mo). Conclusions: Patients treated with the DVD regimen in this study who had failed many prior regimens (median 5) with progressive disease demonstrated a high response rate (50%). In addition, there were few significant or drug-related AEs. Because of these encouraging results, we are now evaluating this regimen in a phase 2 clinical trial in the frontline setting. [Table: see text]

e19508 Background: Nonclinical studies have demonstrated that histone deacetylase inhibitors (HDACi) significantly reduce the growth of MM cells and enhance cytotoxicity of the proteasome inhibitor bortezomib (Velcade). Romidepsin, a pan-HDACi, has previously shown activity for patients (pts) with relapsed or refractory MM when administered as a 4-hr infusion in combination with dexamethasone and bortezomib. Methods: This open-label, multi-center, phase II study (GPI-08–0006) was initiated to evaluate the activity and safety of a 1-hr infusion of romidepsin in combination with bortezomib for MM pts with relapsed or refractory disease and to evaluate the safety and single dose pharmacokinetics (PK)/pharmacodynamics of romidepsin in the first 5 pts. Pts received 10 mg/m2 romidepsin on days 1, 8 and 15 and 1.0 mg/m2 bortezomib on days 1, 4, 8 and 11 of a 28-day cycle. PK sampling and triplicate ECGs were performed at 0, 0.25, 0.5, 1, 2, 3, 4, 6 and 24 hrs after initiation of the first 1-hr infusion of romidepsin. Results: To date, 5 pts have been enrolled (median age 68 [range, 65–72]) 2 pts who relapsed from recent bortezomib-containing regimens experienced minimal responses after 2 cycles. 2 pts have experienced grade 3 thrombocytopenia. No pt had a QTcF value of >480 ms the mean change in QTcF from baseline to Cmax was 4.2 ms (-10 to 13). Values for PK parameters are included in the table . When compared with data from pts who were treated with a 4-hr infusion of 14 mg/m2, the Cmax of the 1-hr infusion of romidepsin 10 mg/m2 was ∼ 20% higher and exposure (AUC0–24hr) was reduced by 70%. Conclusions: Preliminary data suggest that the 1-hr infusion of romidepsin combined with bortezomib is active for pts with MM relapsed or refractory to bortezomib. Based on the initial incidence of grade 3 thrombocytopenia and PK data, additional pts are being treated on the same schedule but with a reduced dose of romidepsin (8 mg/m2). This study continues to enroll pts. [Table: see text] [Table: see text]

e19519 Background: Although the overall survival of MM patients has improved with new treatment options, few studies have evaluated prognostic factors since these new therapies have become available. Monthly ZOL has been incorporated into many of these regimens to reduce skeletal complications. Side effects from ZOL have been reported but their frequency and outcomes have not been well-defined. This retrospective study aimed to identify key baseline and on-treatment prognostic factors among MM patients treated with ZOL. Methods: Three hundred patient charts were consecutively reviewed. Data was collected from the date of MM diagnosis to the date of chart review. Patient chart inclusion criteria required a diagnosis of MM and having received at least one dose of ZOL. Results: The median survival of among patients in this study was 131 months. Significant early risk factors for overall survival included skeletal-related events (SRE), increased serum creatinine, elevated serum calcium, and ISS Stage II or III at diagnosis. Fourteen patients (4.7%) developed osteonecrosis of the jaw (ONJ) after 9–96 months of ZOL treatment. Notably, there was a trend toward an increased risk of ONJ among diabetic patients. Thirteen patients with ONJ remain alive and currently are in remission or with stable disease. One patient with ONJ died while in remission from a myocardial infarction. Among the patients with a follow up of 4–49 months from the diagnosis of ONJ, 2 showed some worsening of this complication, 5 remained stable, while 7 improved or resolved. Patients with ONJ showed an improved overall survival using both landmark and time-dependent analysis. In addition, the overall skeletal morbidity rate (SMR; SREs/year) was 0.16. Notably, patients who developed ONJ had a lower SMR than among patients who did not develop ONJ. Conclusions: These results suggest that skeletal complications are an important prognostic factor for MM. Although ONJ occurs in MM patients, most patients show improvement with proper management and this complication appears to be associated with a reduced risk of SREs and improved overall survival. [Table: see text]

8550 Background: MGUS patients have increased rates of bone resorption with a higher prevalence of osteopenia/osteoporosis than in the normal population. These pts also have an increased risk of fr...

7611 Background: The combination of arsenic trioxide (ATO) and bortezomib (B) has shown synergistic anti-tumor activity against human multiple myeloma (MM) cells in preclinical studies, suggesting that this combination may effectively treat patients with MM. In addition, ascorbic acid (AA) can sensitize MM cells to the cytotoxic effects of ATO. Methods: Patients with relapsed or refractory MM were enrolled in this phase I/II dose-escalation trial in 6 cohorts. Patients were given ATO (0.125 or 0.250 mg/kg), B (0.7, 1.0, or 1.3 mg/m2), and a fixed dose of AA (1000 mg) IV on days 1, 4, 8, and 11 of a 21-day cycle for a maximum of 8 cycles. The planned sample size was a maximum of 27 evaluable patients. The primary endpoint was safety and tolerability of the ATO/B/AA regimen in patients with relapsed or refractory MM. Results: At the time of this interim analysis, 22 patients (median age, 63 years) have been enrolled, and accrual has been completed on all cohorts. This group had failed a median of 4 (range, 3–9) prior therapies. One occurrence of grade 4 thrombocytopenia was observed. One occurrence of asymptomatic arrhythmia led to patient withdrawal. All other adverse events were grade 1 or 2. For the 21 patients evaluable for efficacy, objective responses were observed in 10 patients (43%), including 2 complete (CR), 2 partial (PR), and 5 minor (MR) responses. Only 1 (1 MR) of 6 patients receiving the lowest dose of B (0.7 mg/m2) showed a response, whereas 8 (2 CR, 2 PR, and 4 MR) of 15 patients receiving the higher doses (1.0 or 1.3 mg/m2) responded. Conclusions: The ATO/B/AA regimen was well tolerated by the majority of patients, and produced objective responses in 43% of the patients in this heavily pretreated group. The results of this phase I/II study warrant further clinical evaluation of the ATO/B/AA combination regimen for the treatment of patients with relapsed or refractory MM. [Table: see text]

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]