Phase 1 study of weekly dosing with the investigational oral proteasome inhibitor ixazomib in relapsed/refractory multiple myeloma

Proteasome inhibition is an effective treatment strategy for multiple myeloma. With improving survival, attention is increasingly focusing on ease of administration and toxicity profile. Ixazomib is an investigational, orally bioavailable 20S proteasome inhibitor. Sixty patients with relapsed and/or refractory multiple myeloma were enrolled on this phase 1 trial to evaluate safety and tolerability and determine the maximum tolerated dose (MTD) of single-agent, oral ixazomib given weekly for 3 of 4 weeks. Upon MTD determination, patients were enrolled to 4 different cohorts based on relapsed/refractory status and prior bortezomib and carfilzomib exposure. The MTD was determined to be 2.97 mg/m(2). Dose-limiting toxicities were grade 3 nausea, vomiting, and diarrhea in 2 patients, and grade 3 skin rash in 1 patient. Common drug-related adverse events were thrombocytopenia (43%), diarrhea (38%), nausea (38%), fatigue (37%), and vomiting (35%). The observed rate of peripheral neuropathy was 20%, with only 1 grade 3 event reported. Nine (18%) patients achieved a partial response or better, including 8 of 30 (27%) evaluable patients treated at the MTD. Pharmacokinetic studies suggested a long terminal half-life of 3.6 to 11.3 days, supporting once-weekly dosing. This trial was registered at www.clinicaltrials.gov as #NCT00963820.

Overexpression of Yin Yang 1 in bone marrow-derived human multiple myeloma and its clinical significance

Multiple myeloma (MM) patients initially respond to conventional therapy, however, many develop resistance and have recurrences. We have reported in other tumors that the transcription factor Yin Yang 1 (YY1) is a resistant factor and, thus, we hypothesized that YY1 may be over-expressed in MM. Significantly, higher expression (staining intensity and cell frequency) of YY1 in MM cell lines and in bone marrow-derived (BM) MM from 22 MM patients was observed as compared to expression in normal BM. Higher nuclear YY1 staining was associated with disease progression. Bioinformatic analyses of mRNA in data sets corroborated the above findings and showed significant overexpression of YY1 in MM compared to normal tissues and other hematopoietic disorders. The role of YY1 expression in the regulation of drug resistance was exemplified in a drug-resistant MM cell line transfected with YY1 siRNA and which was shown to be sensitized to bortezomib-induced apoptosis. These findings highlight the potential prognostic significance of YY1 expression level in MM patients and as a therapeutic target.

Results of a phase I/II study (NCT01365559) of carfilzomib (CFZ) replacing bortezomib (BTZ) in BTZ-containing regimens for BTZ-treated patients (pts) with relapsed and refractory multiple myeloma (MM)

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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.

Risk of skin cancer in multiple myeloma patients: A retrospective cohort study

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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<0.001), and melanoma: 1.76 (p = 0.074). SCC SIR was elevated (p<0.001) across each yearly time point from 10 years prior to MM diagnosis through 10 years subsequent to MM diagnosis. BCC SIR was elevated (p <0.002) from 7 through 10 years following MM diagnosis. The SIR markedly increased over time following the diagnosis of MM for both SCC and BCC. Relative risk (RR) was determined for pts treated with bortezomib, immunomodulatory agents, alkylating agents, glucocorticoids, and anthracyclines. There was no significant increase in RR overall or for any specific type of skin CA in relationship to the type or duration of MM treatment. Conclusions: MM pts show an increased risk of skin CA (there was no increase in melanoma incidence), including SCC and BCC. SCC occurred before and following the diagnosis of MM whereas BCC followed the diagnosis of MM. The post-MM diagnosis increase in skin CA was not related to specific drugs used to treat MM.

Weekly MLN9708, an investigational oral proteasome inhibitor (PI), in relapsed/refractory multiple myeloma (MM): Results from a phase I study after full enrollment

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Background: MLN9708 is an investigational, orally bioavailable, potent, reversible, specific inhibitor of the 20S proteasome that has demonstrated antitumor activity in in vivo models of MM. We report safety, activity and pharmacokinetics (PK) of weekly oral MLN9708 in a phase 1 trial in patients (pts) with relapsed and/or refractory MM after full enrollment (NCT00963820). Methods: Pts received MLN9708 (days 1, 8, 15; 28-day cycles) at 0.24–3.95 mg/m2 (dose-escalation phase) and at the MTD, 2.97 mg/m2, in relapsed and refractory (RR), bortezomib (btz)-relapsed, PI-naïve, and prior carfilzomib (CZ) expansion cohorts. Adverse events (AEs) were graded by NCI-CTCAE v3.0. Response was assessed by IMWG uniform criteria. Results: 60 pts (33 male, median age 64 yrs [40–79]) were enrolled, 32 in the dose-escalation phase and 31 to the expansion cohorts (11 RR, 10 btz-relapsed, 6 PI-naïve, 4 CZ; 2 RR and 1 btz-relapsed pts included from MTD dose-escalation cohort). Median time from MM diagnosis was 4.9 yrs (1.5–18.8). Median number of prior regimens was 6 (2–18), including btz, lenalidomide, thalidomide, and CZ in 83%, 95%, 52%, and 13%, respectively; 76% were refractory to last therapy (17% btz-refractory). At data cut-off (Nov 29, 2012) pts had received a median of 2 cycles (1–11); 5 pts remained on treatment. All-grade/grade ≥3 drug-related AEs were seen in 83%/52% of pts; common drug-related grade ≥3 AEs were thrombocytopenia (33%), diarrhea, neutropenia (17%), decreased appetite, fatigue, and lymphopenia (8%). 6 pts (10%) had drug-related PN (no grade ≥3). 5 pts discontinued due to drug-related AEs; 1 pt died on study due to an unrelated AE. By investigator assessment in 41 evaluable pts, responses included1 VGPR, 5 PR, 1 MR, and 15 with SD. MLN9708 was rapidly absorbed, with a terminal half-life of 4–12 days (supporting weekly dosing) and a proportional increase in plasma AUC with dose (0.8–3.95 mg/m2). PK data were similar across expansion cohorts. Conclusions: Current data suggest weekly oral MLN9708 is generally well tolerated with infrequent PN, and shows activity in this heavily pretreated population with prior exposure to immunomodulatory drugs and btz. Clinical trial information: NCT00963820.

A phase I/II study (NCT01541332) of pomalidomide (POM), dexamethasone (DEX), and pegylated liposomal doxorubicin (PLD) for patients with relapsed/refractory (R/R) multiple myeloma (MM)

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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.

Serum B-cell maturation antigen is elevated in multiple myeloma and correlates with disease status and survival

Although TNFRSF17 (also designated as B-cell maturation antigen (BCMA)) is expressed on tumour cells in B-cell malignancies, it has not been found in serum. The present study found that BCMA concentrations were higher in the supernatants of cultured bone marrow mononuclear cells from multiple myeloma (MM) patients than in healthy subjects. Serum BCMA levels were measured in samples from MM patients (n = 209), monoclonal gammopathy of undetermined significance (MGUS) individuals (n = 23) and age-matched controls (n = 40). BCMA was detected in the serum of untreated MM patients (n = 50) and levels were higher than in MGUS patients (P = 0·0157) and healthy subjects (P < 0·0001). Serum BCMA levels were higher among patients with progressive disease (n = 80) compared to those with responsive disease (n = 79; P = 0·0038). Among all MM patients, overall survival was shorter among patients whose serum BCMA levels were above the median (P = 0·001). We also demonstrated that sera from mice with human MM xenografts contained human BCMA, and levels correlated with the change in tumour volume in response to melphalan or cyclophosphamide with bortezomib. These results suggest that serum BCMA levels may be a new biomarker for monitoring disease status and overall survival of MM patients.

A phase I/II study of carfilzomib (CFZ) as a replacement for bortezomib (BTZ) for multiple myeloma (MM) patients (Pts) progressing while receiving a BTZ-containing combination regimen

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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 1/2 trial investigating the safety and efficacy of CFZ as a replacement for BTZ in BTZ‑containing regimens to which pts have progressed. Methods: Eligible pts had to have progressed while receiving their most recent BTZ‑containing regimen after at least 4 doses of BTZ at > 1.0 mg/m² in < 4 weeks per cycle. Combination regimens containing an alkylating agent, anthracycline, or a glucocorticosteroid were eligible. 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 BTZ‑containing 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 19 enrolled pts 13 are evaluable to date and 6 have recently started treatment. Pts received a median of 7 (range, 1-18) prior treatments and 5 (range, 1-5) different BTZ-containing regimens. Pts were treated with CFZ and the following different combinations: bendamustine (BEND) alone, BEND + methylprednisolone, dexamethasone (DEX) alone, DEX + pegylated liposomal doxorubicin, ascorbic acid + cyclophosphamide, and melphalan alone. Pts have completed a median of 3 cycles. Clinical benefit was seen in 10 (77%) pts (complete response = 8%; very good partial response = 8%; partial response = 31%; minor response = 31%) with another 23% showing stable disease. The median time to progression (range: 2-8 months) has not been reached and only 2 pts have progressed. The most common grade 3/4 adverse events were thrombocytopenia occurring in 5 pts (all = grade 3 except 1 event) and fever occurring in two pts (grade 3). Four pts experienced a serious adverse event but no regimen has reached a MTD. Conclusions: These early results suggest that CFZ is an effective and tolerable replacement for BTZ for pts who are refractory to BTZ-containing combination regimens.

A phase I/II trial of melphalan (MEL) combined with panobinostat (PAN) for patients with relapsed or refractory (R/R) multiple myeloma (MM)

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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.

Weekly dosing of the investigational oral proteasome inhibitor MLN9708 in patients (pts) with relapsed/refractory multiple myeloma (MM): A phase I study

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Background: Phase 1 studies are evaluating IV and oral dosing of the reversible proteasome inhibitor MLN9708 in multiple tumor types. We report the safety, MTD, pharmacokinetics (PK), pharmacodynamics, and preliminary responses with weekly oral MLN9708 in pts with relapsed/refractory MM (NCT00963820). Methods: Pts aged ≥18 yrs received MLN9708 on d 1, 8, and 15 of 28-d cycles. In the dose-escalation phase, pts required ≥2 prior therapies (including bortezomib, thalidomide/lenalidomide, and corticosteroids). At the MTD, pts were to be enrolled to relapsed and refractory (RR), bortezomib-relapsed (VR), proteasome inhibitor (PI) naïve, and carfilzomib (CZ) expansion cohorts. Results: 36 pts have been enrolled to date (data cut-off: Dec 1, 2011), 32 in the dose-escalation phase (0.24–3.95 mg/m2) and 8 to expansion cohorts (2 RR, 5 VR, 1 PI naïve; RR and VR cohorts each include 2 pts from MTD dose-escalation cohort). Median age was 64.5 yrs (range 40–79), 53% were male, and median number of prior lines of therapy was 3.5 (range 1-13), including 92%, 92%, 56%, and 8% who had prior bortezomib, lenalidomide, thalidomide, and carfilzomib, respectively. Pts have received a median of 2 cycles (range 1–11); 5 pts remain on treatment. Among 24 DLT-evaluable pts, 3 DLTs were seen: 2 at 3.95 mg/m2 (1 grade 3 rash, 1 grade 3 GI AEs) and 1 at 2.97 mg/m2 (grade 3 GI AEs). The MTD was determined as 2.97 mg/m2. Overall, 69% of pts had drug-related AEs, and 28% had related grade ≥3 AEs, including thrombocytopenia (17%), diarrhea (11%), nausea, neutropenia, and fatigue (each 8%). Only 3 (8%) pts had drug-related peripheral neuropathy (PN; no grade ≥3). 2 pts discontinued due to AEs. In 18 response-evaluable pts, 1 had a VGPR at 3.95 mg/m2, 1 had a PR at 2.97 mg/m2, and 8 have achieved SD durable for up to 9.5 mos. PK analyses showed linear plasma PK (0.8–3.95 mg/m2), Tmax of 0.5-2 hr, and terminal half-life of 7 d for MLN2238 (biologically active hydrolysis product). There was a trend for a dose-dependent increase in whole blood 20S proteasome inhibition. Conclusions: Current data suggest weekly oral MLN9708 is generally well tolerated with infrequent PN, and shows early signs of antitumor activity.

Evaluation of serum B-cell maturation antigen in multiple myeloma

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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.

Comparing effects of kyphoplasty, vertebroplasty, and non-surgical management in a systematic review of randomized and non-randomized controlled studies

PURPOSE

To determine if differences in safety or efficacy exist between balloon kyphoplasty (BKP), vertebroplasty (VP) and non-surgical management (NSM) for the treatment of osteoporotic vertebral compression fractures (VCFs).

METHODS

As of February 1, 2011, a PubMed search (key words: kyphoplasty, vertebroplasty) resulted in 1,587 articles out of which 27 met basic selection criteria (prospective multiple-arm studies with cohorts of ≥ 20 patients). This systematic review adheres to preferred reporting items for systematic reviews and meta-analyses (PRISMA) guidelines.

RESULTS

Pain reduction in both BKP (-5.07/10 points, P < 0.01) and VP (-4.55/10, P < 0.01) was superior to that for NSM (-2.17/10), while no difference was found between BKP/VP (P = 0.35). Subsequent fractures occurred more frequently in the NSM group (22 %) compared with VP (11 %, P = 0.04) and BKP (11 %, P = 0.01). BKP resulted in greater kyphosis reduction than VP (4.8º vs. 1.7°, P < 0.01). Quality of life (QOL) improvement showed superiority of BKP over VP (P = 0.04), along with a trend for disability improvement (P = 0.08). Cement extravasation was less frequent in the BKP (P = 0.01). Surgical intervention within the first 7 weeks yielded greater pain reduction than VCFs treated later.

CONCLUSIONS

BKP/VP provided greater pain relief and fewer subsequent fractures than NSM in osteoporotic VCFs. BKP is marginally favored over VP in disability improvement, and significantly favored in QOL improvement. BKP had a lower risk of cement extravasation and resulted in greater kyphosis correction. Despite this analysis being restricted to Level I and II studies, significant heterogeneity suggests that the current literature is delivering inconsistent messages and further trials are needed to delineate confounding variables.

Animal models of multiple myeloma and their utility in drug discovery

To evaluate potential new therapies and targets for treating multiple myeloma (MM), reproducible, biologically relevant in vivo models are required. Preclinical in vivo models of human MM allow investigators to evaluate novel therapies alone and in combination and quickly translate these results to the clinic where patients directly benefit, whether in the form of a new clinical trial, new doses and schedules, or new drug combinations. Presented in this unit are protocols for generating and maintaining a human extramedullary MM tumor in mice. Additionally, the extramedullary tumor can be excised and digested into a single-cell suspension and the human MM cells injected into mice subcutaneously, intravenously, or intratibially. Once these tumors are generated, they can be used to evaluate novel anti-MM agents and other therapies.