Salvage therapies including retreatment with BCMA-directed approaches after BCMA CAR-T relapses for multiple myeloma.

ABSTRACT: For patients with relapsed/refractory multiple myeloma with a relapse after B-cell maturation antigen (BCMA)-directed chimeric antigen receptor T-cell therapy (CAR-T), optimal salvage treatment strategies remain unclear. BCMA-directed CAR-T and bispecific antibodies (BsAbs) are now commercially available, and the outcomes for retreatment with BCMA-directed approaches are not well studied. We performed a retrospective analysis of 68 patients with relapsed disease after BCMA-directed CAR-T to evaluate outcomes and responses to salvage therapies. With a median follow-up of 13.5 months, median overall survival from time of relapse until death was 18 months (95% confidence interval [CI], 13.2 to not reached [NR]). Fifty-eight patients received subsequent myeloma-directed therapies, with a total of 265 lines of therapy (LOTs). The overall response rate for firstline salvage therapy was 41% (95% CI, 28-55). Among all LOTs, high response rates were observed among those receiving another BCMA-directed CAR-T (89%), BCMA-directed BsAbs (60%), CD38-directed combinations (80% when combined with BsAb; 50% when combined with immunomodulatory drugs and/or proteasome inhibitors), and alkylator-combinations (50% overall; 69% with high-dose alkylators). Thirty-four patients received at least 1 line of salvage BCMA-directed therapy; median progression-free survival was 8.3 months (95% CI, 7.9 to NR), 3.6 months (95% CI, 1.4 to NR), and 1 month (95% CI, 0.9 to NR) with median duration of response (DOR) of 8 months, 4.4 months, and 2.8 months for subsequent BCMA-directed CAR-T, BsAb, and belantamab mafadotin, respectively. Retreatment with BCMA-directed CAR-T and BsAbs can be effective salvage options after BCMA-directed CAR-T relapse; however, DORs appear limited, and further studies with new combinations and alternative targets are warranted.

Antibody and T-cell responses by ultra-deep T-cell receptor immunosequencing after COVID-19 vaccination in patients with plasma cell dyscrasias.

We investigated antibody and coronavirus disease 2019 (COVID-19)-specific T-cell mediated responses via ultra-deep immunosequencing of the T-cell receptor (TCR) repertoire in patients with plasma cell dyscrasias (PCD). We identified 364 patients with PCD who underwent spike antibody testing using commercially available spike-receptor binding domain immunoglobulin G antibodies ≥2 weeks after completion of the initial two doses of mRNA vaccines or one dose of JNJ-78436735. A total of 56 patients underwent TCR immunosequencing after vaccination. Overall, 86% tested within 6 months of vaccination had detectable spike antibodies. Increasing age, use of anti-CD38 or anti-B-cell maturation antigen therapy, and receipt of BNT162b2 (vs. mRNA-1273) were associated with lower antibody titres. We observed an increased proportion of TCRs associated with surface glycoprotein regions of the COVID-19 genome after vaccination, consistent with spike-specific T-cell responses. The median spike-specific T-cell breadth was 3.11 × 10-5 , comparable to those in healthy populations after vaccination. Although spike-specific T-cell breadth correlated with antibody titres, patients without antibody responses also demonstrated spike-specific T-cell responses. Patients receiving mRNA-1273 had higher median spike-specific T-cell breadth than those receiving BNT162b2 (p = 0.01). Although patients with PCD are often immunocompromised due to underlying disease and treatments, COVID-19 vaccination can still elicit humoral and T-cell responses and remain an important intervention in this patient population.

The surfaceome of multiple myeloma cells suggests potential immunotherapeutic strategies and protein markers of drug resistance.

The myeloma surface proteome (surfaceome) determines tumor interaction with the microenvironment and serves as an emerging arena for therapeutic development. Here, we use glycoprotein capture proteomics to define the myeloma surfaceome at baseline, in drug resistance, and in response to acute drug treatment. We provide a scoring system for surface antigens and identify CCR10 as a promising target in this disease expressed widely on malignant plasma cells. We engineer proof-of-principle chimeric antigen receptor (CAR) T-cells targeting CCR10 using its natural ligand CCL27. In myeloma models we identify proteins that could serve as markers of resistance to bortezomib and lenalidomide, including CD53, CD10, EVI2B, and CD33. We find that acute lenalidomide treatment increases activity of MUC1-targeting CAR-T cells through antigen upregulation. Finally, we develop a miniaturized surface proteomic protocol for profiling primary plasma cell samples with low inputs. These approaches and datasets may contribute to the biological, therapeutic, and diagnostic understanding of myeloma.

Outcomes of kidney transplant recipients with ESKD due to plasma cell dyscrasia: A case series.

Transplant centers have historically been reluctant to proceed with kidney transplantation in individuals with plasma cell dyscrasias (PCDs) due to concern for high rates of PCD recurrence and PCD-related mortality. As novel therapies for PCDs have improved hematologic outcomes, strategies to optimize kidney transplantation in individuals with PCD-mediated kidney disease are needed. In this single-center case series we discuss our protocol for the transplantation of individuals with ESKD attributed to PCD as well as the hematologic and allograft outcomes of 12 kidney transplant recipients with ESKD attributed to PCD. Median follow-up time after kidney transplantation was 44 months (IQR 36, 84). All patients had a functioning allograft 1 year after kidney transplantation. 9/12 patients were alive and had a functioning allograft 5 years after kidney transplantation. Five patients experienced relapse of PCD (of whom three responded well to subsequent therapies) and four patients developed secondary malignancies, including three patients with urologic malignancies. This case series demonstrates that patients with kidney disease attributed to PCD have favorable outcomes with kidney transplantation. Transplant evaluation in patients with PCDs should involve a multidisciplinary team of transplant nephrologists and oncologists to select appropriate candidates. Providers should consider screening for urologic malignancies pre- and post-transplantation.

Individualized genetic makeup that controls natural killer cell function influences the efficacy of isatuximab immunotherapy in patients with multiple myeloma.

BACKGROUND: Phase IIb clinical trial with isatuximab (Isa)-lenalidomide (Len)-dexamethasone (Dex) showed an improved progression-free survival (PFS) in patients with relapsed or refractory multiple myeloma (RRMM), but the efficacy varied by patient. Antibody-dependent cell-mediated cytotoxicity (ADCC) by natural killer (NK) cells plays a crucial role in arbitrating antitumor activities of therapeutic-antibodies. We tested if patient-specific genetic makeup known to set NK cell functional threshold influence response to Isa-Len-Dex therapy. METHODS: We characterized 57 patients with RRMM receiving Isa-Len-Dex for polymorphisms of killer-cell immunoglobulin-like receptors (KIR), human leukocyte antigen (HLA) class I, and FCGR3A loci. In vitro ADCC assay, coincubating primary NK cells expressing specific KIR repertoire with multiple myeloma cell lines (MM cells) expressing selected HLA class I ligands, was used to confirm the identified genetic correlatives of clinical response. RESULTS: Patients with KIR3DL2+ and its cognate-ligand HLA-A3/11+ had superior PFS than patients missing this combination (HR=0.43; p=0.02), while patients carrying KIR2DL1+ and HLA-C2C2+ compared with to patients missing this pair showed short PFS (HR=3.54; p=0.05). Patients with KIR3DL2+ and HLA-A3/11+ plus high-affinity FCGR3A-158V allele showed the most prolonged PFS (HR=0.35; p=0.007). Consistent with these clinical data, mechanistic experiments demonstrated that NK cells expressing KIR3DL2 trigger greater ADCC when MM cells express HLA-A3/11. Inversely, NK cells expressing KIR2DL1 do not kill if MM cells express the HLA-C2C2 ligand. NK cells expressing high-affinity FCGR3A-158VV-induced greater ADCC compared with those with low-affinity FCGR3A-158FF. CONCLUSIONS: Our results suggest that KIR3DL2+ and HLA-A3/11+ with FCGR3A-158V markers lead to enhanced Isa-dependent NK-mediated cytolysis against MM cells and results in improved PFS in patients with RRMM treated by Isa-Len-Dex. Moreover, the presence of KIR2DL1+ and HLA-C2C2+ identifies patients who may have a lower response to Isa-Len-Dex therapy linked to a reduced NK-mediated ADCC. These biomarkers could potentially identify, via precision medicine, patients more likely to respond to Isa-Len-Dex immunotherapy. TRIAL REGISTRATION NUMBER: NCT01749969.

Early Time-to-Tocilizumab after B Cell Maturation Antigen-Directed Chimeric Antigen Receptor T Cell Therapy in Myeloma.

Preemptive administration of tocilizumab (toci) to manage cytokine release syndrome (CRS) after chimeric antigen receptor T cell (CAR-T) therapy may reduce rates of serious CRS but conversely may worsen neurotoxicity or risk of infections. Optimal toci administration strategies for patients with relapsed/refractory multiple myeloma (RRMM) receiving B cell maturation antigen (BCMA)-directed CAR-T therapies have not been evaluated. The objective of this study was to identify whether shorter time-to-toci intervals (hours between first fever attributed to CRS and first dose of toci) have any impact on therapy-related toxicities or clinical outcomes among patients with RRMM receiving BCMA-directed CAR-T therapies. We retrospectively analyzed our institution's experience with 4 BCMA-directed CAR-T therapies (idecabtagene vicleucel, bb21217, ciltacabtagene autoleucel, and orvacabtagene autoceucel) for RRMM over a 3-year period ending in June 2020. We divided patients based on the administration of toci and median time-to-toci interval into early-toci (time-to-toci ≤50th percentile), late-toci (time-to-toci >50th percentile), and no-toci (no toci received) groups. We compared the early-toci and late-toci groups with regard to patient characteristics, weight-based CAR-T toxicities, selected toxicities (CRS, neurotoxicity, macrophage activation syndrome, or infections), and clinical outcomes. Of 50 analyzed patients with a median follow-up of 15.3 months, 76% (n = 38) received ≥1 dose of toci (range, 1 to 3) and were classified into early-toci (time-to-toci ≤12 hours) or late-toci (time-to-toci >12 hours) groups. The 2 groups (n = 19 each) had similar CRS grade distributions, hours to CRS onset, CRS-related biomarkers, and incidences of neurotoxicity or severe infections; however, weight-adjusted CAR-T cell doses were higher in the early-toci group (median 5.99 versus 3.80 × 106 cells/kg, P < 0.01). Peak CRS grades (range, 0 to 2) using American Society for Transplantation and Cellular Therapy consensus criteria, neurotoxicity rates, and rates of severe infections were similar between groups; however, the median CRS duration was 18.6 hours for the early-toci group versus 84.7 hours for the late-toci group. The median progression-free survival was 35.7 months in the early-toci group and 13.2 months in the late-toci group. While limited by small sample size and known confounders such as CAR-T cell dose, our analysis suggests that preemptive toci strategies for CRS management with BCMA-directed CAR-T therapy-specifically, toci administration within 12 hours of the first fever attributed to CRS-do not appear to increase rates of therapy-related toxicities or compromise efficacy. However, total CRS duration may be shorter with early-toci workflows. Prospective validation of our findings may lead to improved safety and cost-effectiveness profiles for CAR-T therapy in RRMM.

Phase 1b trial of isatuximab, an anti-CD38 monoclonal antibody, in combination with carfilzomib as treatment of relapsed/refractory multiple myeloma.

BACKGROUND: Isatuximab (Isa), an anti-CD38 monoclonal antibody, and carfilzomib (K), a next-generation proteasome inhibitor (PI), both have potent single-agent activity in relapsed and refractory multiple myeloma (RRMM). METHODS: This phase 1b study evaluated the combination of Isa and K in 33 patients with RRMM. Isa was administered by intravenous infusion in 3 dosing cohorts: dose level 1 (Isa at 10 mg/kg biweekly), dose level 2 (DL2; Isa at 10 mg/kg weekly for 4 doses and then biweekly), and dose level 3 (Isa at 20 mg/kg weekly for 4 doses and then biweekly) and all patients received K (20 mg/m2 intravenously for cycle 1, days 1 and 2, and then 27 mg/m2 for all subsequent doses). A standard 3+3 dose-escalation design was used, no dose-limiting toxicity was observed, and the maximum tolerated dose was not reached. An expansion cohort of 18 patients was enrolled at DL2 to further evaluate safety and efficacy. Responses were assessed with the International Myeloma Working Group response criteria, and patients continued treatment until disease progression or unacceptable toxicity. RESULTS: With a median follow-up of 26.7 months, in this heavily pretreated population with a median of 3 prior lines (refractory to PIs and immunomodulatory drugs, 76%; refractory to K, 27%), the overall response rate was 70% (stringent complete response/complete response, 4; very good partial response, 8; partial response, 11). The median progression-free survival was 10.1 months, and the 2-year survival probability was 76%. The most common treatment-related adverse events (grade 2 or higher) were anemia, leukopenia, neutropenia, thrombocytopenia, hypertension, and infection. Infusion reactions were common (55%) but did not limit dosing. CONCLUSIONS: Treatment with Isa plus K was well tolerated with no unexpected toxicity. The combination was effective despite the enrollment of heavily pretreated patients with RRMM. LAY SUMMARY: This phase 1b study was designed to assess the safety, pharmacokinetics, and preliminary efficacy of isatuximab and carfilzomib in patients with relapsed and refractory multiple myeloma. Thirty-three patients were treated: 15 in dose escalation and 18 in dose expansion. Patients received an average of 10 cycles. The treatment was safe and effective. No unexpected toxicity or drug-drug interactions were noted. Seventy percent of the subjects responded to therapy, and the progression-free survival was 10.1 months.

Benzodiazepine and zolpidem prescriptions during autologous stem cell transplantation.

Multiple myeloma patients undergoing autologous stem cell transplantation (ASCT) may receive benzodiazepine or zolpidem-class (B/Z) medications despite their risks in older patients. Of 205 myeloma patients (36% aged 65+) who underwent ASCT at our institution between 2017 and 2018, we found that B/Z prescription rates for anxiety/insomnia rose significantly from 26% before ASCT to 38% at discharge and 39% at Day +100. B/Z initiation while hospitalized was a strong predictor of B/Z persistence at Day +100. Our findings highlight the role of these potentially inappropriate medications during hospitalizations for ASCT, a period where nonpharmacologic strategies for managing anxiety/insomnia may be feasible.

Serial comprehensive geriatric and quality of life assessments in adults age ≥ 50 years undergoing autologous hematopoietic cell transplantation.

OBJECTIVES: We sought to examine the natural history of geriatric assessment (GA) and quality of life (QOL) domains among adults age ≥ 50 years undergoing autologous hematopoietic cell transplantation (autoHCT). MATERIALS AND METHODS: A QOL tool and cancer-specific GA were completed before autoHCT in patients ≥50 years, and at 100 days, six months, and one year post-transplant. RESULTS: One hundred eighty-four patients completed the pre-transplant QOL/GA assessment, 169 (92%) completed the 100-day assessment, 162 (88%) completed the six-month assessment, and 145 (79%) completed the twelve-month assessment. Functional status, as measured by instrumental activities of daily living (IADL), decreased from baseline to day 101 (mean change -0.42 points, 95% CI, -0.75 to -0.09, p = 0.01) but returned to baseline by one year. Physical function as measured by Medical Outcomes Study-Physical Health (MOS-PH) increased by mean of 3.27 points (95% CI, -0.02 to 6.56, p = 0.05) by one year. Physician-rated KPS improved by one year, but patient-rated KPS did not. No QOL metric deteriorated from baseline. Baseline factors predictive of IADL and MOS-PH as measured over time included comorbidities and disease status at transplant. IADL and MOS-PH as measured over time were not significantly associated with age. CONCLUSIONS: AutoHCT for adults age ≥ 50 years resulted in an initial decrease in functional status, with subsequent improvement back to baseline by one year. Physical health and QOL measures were improved or unchanged over time. AutoHCT is well tolerated in well selected older patients, using patient reported geriatric metrics as outcomes.

CRISPR-based screens uncover determinants of immunotherapy response in multiple myeloma.

Cancer cells commonly develop resistance to immunotherapy by loss of antigen expression. Combinatorial treatments that increase levels of the target antigen on the surface of cancer cells have the potential to restore efficacy to immunotherapy. Here, we use our CRISPR interference- and CRISPR activation-based functional genomics platform to systematically identify pathways controlling cell surface expression of the multiple myeloma immunotherapy antigen B-cell maturation antigen (BCMA). We discovered that pharmacologic inhibition of HDAC7 and the Sec61 complex increased cell surface BCMA, including in primary patient cells. Pharmacologic Sec61 inhibition enhanced the antimyeloma efficacy of a BCMA-targeted antibody-drug conjugate. A CRISPR interference chimeric antigen receptor T cells (CAR-T cells) coculture screen enabled us to identify both antigen-dependent and antigen-independent mechanisms controlling response of myeloma cells to BCMA-targeted CAR-T cells. Thus, our study shows the potential of CRISPR screens to uncover mechanisms controlling response of cancer cells to immunotherapy and to suggest potential combination therapies.

Proteasome inhibitor-induced modulation reveals the spliceosome as a specific therapeutic vulnerability in multiple myeloma.

Enhancing the efficacy of proteasome inhibitors (PI) is a central goal in myeloma therapy. We proposed that signaling-level responses after PI may reveal new mechanisms of action that can be therapeutically exploited. Unbiased phosphoproteomics after treatment with the PI carfilzomib surprisingly demonstrates the most prominent phosphorylation changes on splicing related proteins. Spliceosome modulation is invisible to RNA or protein abundance alone. Transcriptome analysis after PI demonstrates broad-scale intron retention, suggestive of spliceosome interference, as well as specific alternative splicing of protein homeostasis machinery components. These findings lead us to evaluate direct spliceosome inhibition in myeloma, which synergizes with carfilzomib and shows potent anti-tumor activity. Functional genomics and exome sequencing further support the spliceosome as a specific vulnerability in myeloma. Our results propose splicing interference as an unrecognized modality of PI mechanism, reveal additional modes of spliceosome modulation, and suggest spliceosome targeting as a promising therapeutic strategy in myeloma.

Impact of Plerixafor Use at Different Peripheral Blood CD34+ Thresholds on Autologous Stem Cell Collection in Patients with Multiple Myeloma.

Patients with multiple myeloma (MM) scheduled for autologous stem cell transplantation must undergo autologous stem cell mobilization; unfortunately, however, many do not obtain an adequate collection yield. Despite the availability of plerixafor, its widespread and uniform use is limited by its cost, and consequently, many institutions have adopted various risk-adapted algorithms. We report our mobilization experience as we have modified our plerixafor algorithm to a more liberal one, with the expectation of greater collection efficiency and mobilization success with higher plerixafor use. A total of 344 mobilization attempts were analyzed over 3 time periods and using 3 different peripheral blood CD34+ cell counts to guide plerixafor use: <15/µL (n = 66), <20/µL (n = 130), and <40/µL (n = 148). The primary endpoints were evaluation of changes in mean plerixafor utilization and apheresis days and assessment of the impact on overall mobilization costs. Secondary endpoints were a description of the impact of lenalidomide use on mobilization and evaluation of the rate of mobilization failure. We found that mean plerixafor use increased from 1.32 to 1.65 to 1.74 doses per mobilization (P = .026) and the mean days of apheresis decreased from 2.15 to 2.17 to 1.89 days per mobilization for the <15/µL, <20/µL, and <40/µL cohorts, respectively (P = .011). The combined cost of plerixafor and apheresis procedures at a threshold of 40/µL is close to that at a threshold of 15/µL, while saving 26 apheresis days per 100 patients. In general, there were low rates of mobilization failure across all thresholds. Patients who received more than 6 cycles of lenalidomide demonstrated impaired mobilization and required more apheresis sessions (P < .013) and greater plerixafor use (P < .001) to achieve target stem cell yields. Overall, using plerixafor in patients with MM, with a day 4 pCD34 count of <40/µL is a reasonable and cost-effective strategy to optimize apheresis utilization.

Preclinical Efficacy and Safety Comparison of CD3 Bispecific and ADC Modalities Targeting BCMA for the Treatment of Multiple Myeloma.

The restricted expression pattern of B-cell maturation antigen (BCMA) makes it an ideal tumor-associated antigen (TAA) for the treatment of myeloma. BCMA has been targeted by both CD3 bispecific antibody and antibody-drug conjugate (ADC) modalities, but a true comparison of modalities has yet to be performed. Here we utilized a single BCMA antibody to develop and characterize both a CD3 bispecific and 2 ADC formats (cleavable and noncleavable) and compared activity both in vitro and in vivo with the aim of generating an optimal therapeutic. Antibody affinity, but not epitope was influential in drug activity and hence a high-affinity BCMA antibody was selected. Both the bispecific and ADCs were potent in vitro and in vivo, causing dose-dependent cell killing of myeloma cell lines and tumor regression in orthotopic myeloma xenograft models. Primary patient cells were effectively lysed by both CD3 bispecific and ADCs, with the bispecific demonstrating improved potency, maximal cell killing, and consistency across patients. Safety was evaluated in cynomolgus monkey toxicity studies and both modalities were active based on on-target elimination of B lineage cells. Distinct nonclinical toxicity profiles were seen for the bispecific and ADC modalities. When taken together, results from this comparison of BCMA CD3 bispecific and ADC modalities suggest better efficacy and an improved toxicity profile might be achieved with the bispecific modality. This led to the advancement of a bispecific candidate into phase I clinical trials.

Review of the patient-centered communication landscape in multiple myeloma and other hematologic malignancies.

OBJECTIVES: To identify factors limiting and facilitating patient-centered communication (PCC) in the United States hematology-oncology setting, with a focus on multiple myeloma (MM), given the limited attention to PCC and rapid pace of change that has taken place in this setting. METHODS: A literature search was performed from 2007 to 2017 to identify published articles and congress abstracts related to clinician-patient communication and treatment decision-making in oncology. Search results were evaluated by year of publication and disease area. A thematic assessment was performed to identify factors limiting and promoting PCC for patients with MM and other hematologic malignancies. RESULTS: Of the 6673 publications initially retrieved, 18 exclusively reported findings in patients with hematologic malignancies and were included in this review. We identified three critical, but modifiable, barriers to PCC in the hematologic malignancy setting, including insufficient information exchange, treatment goal misalignment, and discordant role preferences in treatment decision-making. Factors that enhanced interaction quality included educational programs for clinicians and patients. CONCLUSIONS: Patients with MM and other hematologic malignancies experience a distinct set of challenges that may affect PCC. PRACTICE IMPLICATIONS: Clinicians have the opportunity to improve patient care by proactively addressing the identified barriers and implementing strategies demonstrated to improve PCC.

Limitation in Patient-Reported Function Is Associated with Inferior Survival in Older Adults Undergoing Autologous Hematopoietic Cell Transplantation.

Although the use of geriatric assessment (GA) in the allogeneic hematopoietic cell transplantation (HCT) setting has been reported, few studies have evaluated the impact of patient-reported function on autologous HCT (autoHCT) outcomes. In this study, GA, including the administration of Functional Assessment of Cancer Therapy-Bone Marrow Transplant (FACT-BMT) quality of life tool, was performed in 184 patients age ≥50 years (median age, 61 years; range, 50 to 75 years) before autoHCT. Associations among GA findings, quality of life metrics, and post-transplantation outcomes were evaluated using Cox regression. Indications for autoHCT included multiple myeloma (73%), non-Hodgkin lymphoma (20%), and other disorders (7%). The median progression-free survival (PFS) was 28 months, whereas the median overall survival (OS) was not reached. In unadjusted analysis, both PFS and OS were significantly associated with 5 GA components: limitation in instrumental activities of daily living, patient-reported Karnofsky Performance Status (KPS), and the Physical, Functional, and BMT subscale scores of the FACT-BMT. In multivariate analysis, 3 components-limitation in instrumental activities of daily living, patient-reported KPS, and FACT-BMT Physical subscale-remained predictive of both PFS and OS when adjusted for age, provider-reported KPS, disease status, and HCT comorbidity index. In older adults undergoing autoHCT, limitation in any 1 of 3 patient-reported measures of functional status was independently associated with inferior PFS and OS, even after adjusting for known prognostic factors.

The p97 Inhibitor CB-5083 Is a Unique Disrupter of Protein Homeostasis in Models of Multiple Myeloma.

Inhibition of the AAA ATPase, p97, was recently shown to be a novel method for targeting the ubiquitin proteasome system, and CB-5083, a first-in-class inhibitor of p97, has demonstrated broad antitumor activity in a range of both hematologic and solid tumor models. Here, we show that CB-5083 has robust activity against multiple myeloma cell lines and a number of in vivo multiple myeloma models. Treatment with CB-5083 is associated with accumulation of ubiquitinated proteins, induction of the unfolded protein response, and apoptosis. CB-5083 decreases viability in multiple myeloma cell lines and patient-derived multiple myeloma cells, including those with background proteasome inhibitor (PI) resistance. CB-5083 has a unique mechanism of action that combines well with PIs, which is likely owing to the p97-dependent retro-translocation of the transcription factor, Nrf1, which transcribes proteasome subunit genes following exposure to a PI. In vivo studies using clinically relevant multiple myeloma models demonstrate that single-agent CB-5083 inhibits tumor growth and combines well with multiple myeloma standard-of-care agents. Our preclinical data demonstrate the efficacy of CB-5083 in several multiple myeloma disease models and provide the rationale for clinical evaluation as monotherapy and in combination in multiple myeloma. Mol Cancer Ther; 16(11); 2375-86. ©2017 AACR.

Kidney Transplantation for Kidney Failure Due to Multiple Myeloma: Case Reports.

Transplantation centers have historically considered a history of multiple myeloma as a contraindication to kidney transplantation due to high recurrence rates and poor transplant survival. However, there have been significant advances in the treatment of multiple myeloma, with improved patient survival, which may allow for successful kidney transplantation in these patients. We report on 4 patients who underwent kidney transplantation at our institution between 2009 and 2015 after having achieved a very good partial response or better with chemotherapy and autologous stem cell transplantation. All 4 patients received kidneys from living donors; 2 underwent induction therapy with basiliximab, and 2, with thymoglobulin. One patient had progression of myeloma, which responded well to therapy. All had functioning transplants at 1 year after kidney transplantation. No patients experienced a rejection episode or infections with BK polyomavirus or cytomegalovirus, with follow-up ranging from 16 to 58 months after kidney transplantation. Our experience suggests that kidney transplantation is feasible in a subset of patients with multiple myeloma. Future studies are necessary to compare outcomes in these patients with other high-risk patients undergoing kidney transplantation.

Antibody-drug conjugate targeting CD46 eliminates multiple myeloma cells.

Multiple myeloma is incurable by standard approaches because of inevitable relapse and development of treatment resistance in all patients. In our prior work, we identified a panel of macropinocytosing human monoclonal antibodies against CD46, a negative regulator of the innate immune system, and constructed antibody-drug conjugates (ADCs). In this report, we show that an anti-CD46 ADC (CD46-ADC) potently inhibited proliferation in myeloma cell lines with little effect on normal cells. CD46-ADC also potently eliminated myeloma growth in orthometastatic xenograft models. In primary myeloma cells derived from bone marrow aspirates, CD46-ADC induced apoptosis and cell death, but did not affect the viability of nontumor mononuclear cells. It is of clinical interest that the CD46 gene resides on chromosome 1q, which undergoes genomic amplification in the majority of relapsed myeloma patients. We found that the cell surface expression level of CD46 was markedly higher in patient myeloma cells with 1q gain than in those with normal 1q copy number. Thus, genomic amplification of CD46 may serve as a surrogate for target amplification that could allow patient stratification for tailored CD46-targeted therapy. Overall, these findings indicate that CD46 is a promising target for antibody-based treatment of multiple myeloma, especially in patients with gain of chromosome 1q.