Anti-myeloma Activity Research Articles

A Phase 1 Dose-Escalation Study of LH031, a Kinesin Spindle Protein Inhibitor, in Patients with Refractory/Resistance Multiple Myeloma

PURPOSE: Kinesin spindle protein is an attractive target for cancer treatment since it plays an important role in mitosis without directly affecting microtubules. LH031 is a highly selective inhibitor of kinesin spindle protein, which has demonstrated preclinical antimyeloma activity.. This phase 1 study was conducted to evaluated dose limiting toxicities (DLTs) and determined a maximum tolerated dose (MTD) for LH031 in Chinese patients with Refractory/Resistance Multiple Myeloma (RRMM).The pharmacokinetics (PK) and preliminary efficacy of LH031 were also evaluated. METHODS: A non-randomized, single-center, open-label, dose-escalation phase 1 trial was conducted to evaluate the safety, tolerability, pharmacokinetics and efficacy of single or multiple escalation dose (20 mg, 30 mg, 40 mg, 50 mg) of LH031 given as schedule of oral once a day. LH031 was administered on Day 1~5 of each week for 3 weeks (21 days) per cycle. A standard 3+3 dose escalation design was employed. An expansion cohort was conducted at the MTD. Pharmacokinetics was evaluated in plasma. A major efficacy evaluation was performed at the end of each treatment cycle. RESULTS: The study is still on going, at present there are 6 patients received LH031 and completion of all visits, divided equally into 20mg and 30mg cohort. Patients in each cohort had received a median of 6 prior therapies. DLTs reported in two patients dosed at 30mg. Both of the DLTs were neutropenia. The most commonly reported treatment-related AEs were hematological toxicity (e.g. neutropenia, lymphocytopenia, leukocytopenia) that were similar to other Eg5 inhibitors. The main severe adverse events (CTCAE grade 3 or 4) in the 20mg and 30 mg dose groups were leukocytopenia and neutropenia, and they were all reversible. Neurotoxicity related to LH031 was not observed. Efficacy data demonstrated that the best response was Stable Disease(SD) and Disease Control Rate (DCR, ≥SD[≥8 weeks]) was 50%. The longest treatment time was 177 days, even though PFS was determined according to the last tumor evaluation before the COVID period (D88). The PK data shows that T1/2 are approximately 20h in Chinese patients, which is longer than Caucasian (10h); Chinese AUC for 20mg is also higher than that of Caucasian (1996 h*ng/ml vs. 476 h*ng/ml) ; the exposure at 20mg dose group is close to that at 50 mg dose in Caucasian. These PK parameter indicates that the elimination of LH031 is slower in Chinese patients compared with Caucasian. CONCLUSIONS: The current phase 1 study showed that LH031 was an accepted safety profile at 20mg. DLTs was expected and reversible. MTD is to be determined by recruiting 3 more subjects at 20mg dose. It demonstrated that the elimination rate of LH031 in Chinese patients was slower than Caucasian. The monotherapy showed some benefit to RRMM, Phase 2 clinical trials are being planned to include various combination therapies with existing treatments (e.g. lenalidomide, dexamethasone, bortezomib) for MM to benefit more potential refractory/resistance MM patients. Disclosures Song: Link Health Group: Current Employment.

Characterization of a PERK Kinase Inhibitor with Anti-Myeloma Activity.

Simple SummaryMultiple myeloma is a bone marrow cancer that represents a severe health threat. The drugs used nowadays in chemotherapy often encounter resistance leading to a dramatic loss of their efficacy, which consequently affects patients’ survival. Previous studies have shown that the protein kinase R (PKR)-like ER kinase (PERK) pathway, which is one of the three branches of the unfolded protein response, is highly activated in multiple myeloma, possibly contributing to the chemotherapy resistance that these patients develop. In this study, we have used the compound GSK2606414, which is a PERK inhibitor, and found that myeloma cells are highly sensitive to this molecule. These effects were more pronounced when the inhibitor was used in combination with an anti-myeloma drug such as the proteasome inhibitor bortezomib, suggesting that the PERK pathway could be a potential therapeutic target for the treatment of multiple myeloma patients.Due to increased immunoglobulin production and uncontrolled proliferation, multiple myeloma (MM) plasma cells develop a phenotype of deregulated unfolded protein response (UPR). The eIF2-alpha kinase 3 [EIF2αK3, protein kinase R (PKR)-like ER kinase (PERK)], the third known sensor of endoplasmic reticulum (ER) stress, is a serine-threonine kinase and, like the other two UPR-related proteins, i.e., IRE1 and ATF6, it is bound to the ER membrane. MM, like other tumors showing uncontrolled protein secretion, is highly dependent to UPR for survival; thus, inhibition of PERK can be an effective strategy to suppress growth of malignant plasma cells. Here, we have used GSK2606414, an ATP-competitive potent PERK inhibitor, and found significant anti-proliferative and apoptotic effects in a panel of MM cell lines. These effects were accompanied by the downregulation of key components of the PERK pathway as well as of other UPR elements. Consistently, PERK gene expression silencing significantly increased cell death in MM cells, highlighting the importance of PERK signaling in MM biology. Moreover, GSK2606414, in combination with the proteasome inhibitor bortezomib, exerted an additive toxic effect in MM cells. Overall, our data suggest that PERK inhibition could represent a novel combinatorial therapeutic approach in MM.

Melflufen: A Peptide-Drug Conjugate for the Treatment of Multiple Myeloma.

Despite the availability of new therapies that have led to improved outcomes for patients with multiple myeloma, most patients will eventually relapse. With triplet and even quadruplet combination therapies becoming standard in the first and second line, many patients will have few treatment options after second-line treatment. Melflufen (melphalan flufenamide) is a first-in-class peptide–drug conjugate (PDC) that targets aminopeptidases and rapidly releases alkylating agents into tumor cells. Once inside the tumor cells, melflufen is hydrolyzed by peptidases to release alkylator molecules, which become entrapped. Melflufen showed anti-myeloma activity in myeloma cells that were resistant to bortezomib and the alkylator melphalan. In early phase studies (O-12-M1 and HORIZON [OP-106]), melflufen plus dexamethasone has demonstrated encouraging clinical activity and a manageable safety profile in heavily pretreated patients with relapsed/refractory multiple myeloma, including those with triple-class refractory disease and extramedullary disease. The Phase III OCEAN study (OP-104) is further evaluating melflufen plus dexamethasone in patients with relapsed/refractory multiple myeloma. The safety profile of melflufen is characterized primarily by clinically manageable hematologic adverse events. Melflufen, with its novel mechanism of action, has the potential to provide clinically meaningful benefits to patients with relapsed/refractory multiple myeloma, including those with high unmet needs.

Anti-bacterial and anti-viral nanchangmycin displays anti-myeloma activity by targeting Otub1 and c-Maf

As a deubiqutinase Otub1 stabilizes and promotes the oncogenic activity of the transcription factor c-Maf in multiple myeloma (MM), a malignancy of plasma cells. In the screen for bioactive inhibitors of the Otub1/c-Maf axis for MM treatment, nanchangmycin (Nam), a polyketide antibiotic, was identified to suppress c-Maf activity in the presence of Otub1. By suppressing Otub1, Nam induces c-Maf polyubiquitination and subsequent degradation in proteasomes but does not alter its mRNA level. Consistently, Nam downregulates the expression of CCND2, ARK5, and ITGB7, the downstream genes regulated by c-Maf, and promotes MM cell apoptosis as evidenced by PARP and Caspase-3 cleavage, as well as Annexin V staining. In line with the hypothesis, overexpression of Otub1 partly rescues Nam-induced MM cell apoptosis, and interestingly, when Otub1 is knocked down, Nam-decreased MM cell survival is also partly ablated, suggesting Otub1 is essential for Nam anti-MM activity. Nam also displays potent anti-MM activity synergistically with Doxorubicin or lenalidomide. In the in vivo assays, Nam almost completely suppresses the growth of MM xenografts in nude mice at low dosages but it shows no toxicity. Given its safety and efficacy, Nam has a potential for MM treatment by targeting the Otub1/c-Maf axis.

The FMS like Tyrosine Kinase 3 (FLT3) Is Overexpressed in a Subgroup of Multiple Myeloma Patients with Inferior Prognosis.

Therapy resistance remains a major challenge in the management of multiple myeloma (MM). We evaluated the expression of FLT3 tyrosine kinase receptor (FLT3, CD135) in myeloma cells as a possible clonal driver. FLT3 expression was analyzed in bone marrow biopsies of patients with monoclonal gammopathy of undetermined significance or smoldering myeloma (MGUS, SMM), newly diagnosed MM (NDMM), and relapsed/refractory MM (RRMM) by immunohistochemistry (IHC). FLT3 gene expression was analyzed by RNA sequencing (RNAseq) and real-time PCR (rt-PCR). Anti-myeloma activity of FLT3 inhibitors (midostaurin, gilteritinib) was tested in vitro on MM cell lines and primary MM cells by 3H-tymidine incorporation assays or flow cytometry. Semi-quantitative expression analysis applying a staining score (FLT3 expression IHC-score, FES, range 1–6) revealed that a high FES (>3) was associated with a significantly shorter progression-free survival (PFS) in NDMM and RRMM patients (p = 0.04). RNAseq and real-time PCR confirmed the expression of FLT3 in CD138-purified MM samples. The functional relevance of FLT3 expression was corroborated by demonstrating the in vitro anti-myeloma activity of FLT3 inhibitors on FLT3-positive MM cell lines and primary MM cells. FLT3 inhibitors might offer a new targeted therapy approach in a subgroup of MM patients displaying aberrant FLT3 signaling.

Daratumumab subcutaneous formulation for the treatment of multiple myeloma

ABSTRACT Introduction Intravenous daratumumab has shown unprecedented anti-myeloma activity when used as a single agent or in combination with other myeloma therapies. Recently, a subcutaneous formulation of daratumumab was approved for use in both the United States and European Union based on data which showed shorter infusion times and decreased rate of infusion reactions while maintaining non-inferior efficacy. Areas covered We cover the physiology behind subcutaneous daratumumab and summarize the relevant clinical data with a particular focus on the pharmacokinetics, pharmacodynamics, safety, and clinical efficacy. Articles used to generate this review were obtained by searching pubmed (https://pubmed.ncbi.nlm.nih.gov/) with the search terms ‘subcutaneous daratumumab’ and ‘daratumumab hyaluronidase’. Expert opinion Subcutaneous daratumumab is associated with lower risk of infusion reactions and decreased administration time while maintaining non-inferior efficacy. We support the use of subcutaneous daratumumab for all approved indications and for investigational use moving forward.

Abstract 5622: scRNA-seq reveals restructuring of the immune microenvironment of multiple myeloma following treatment with an IAP antagonist

Abstract Previously, the IAP antagonist LCL161 was shown to have robust anti-myeloma activity in a transgenic mouse model where an acute inflammatory response accompanied a reduction in tumor burden. In order to fully examine alterations to the immune microenvironment, murine splenocytes from twenty mice transplanted with Vk12598 myeloma and administered single-agent treatment regimens of LCL161, cyclophosphamide, or bortezomib were harvested after 24 hours and subjected to single cell RNA-seq sequencing. After initial removal of erythrocytic and mitochondrial expressing cells, count matrices of over 50,000 total cells span twenty murine whole spleen samples. In an examination of the myeloid component, we identified 13 clusters of immune cells with unique compositions across samples due to differing treatment regimens and initial tumor burden. While minimally present in all seven non-transplanted mice, macrophages with elevated expression of complement activation system genes (C1q) were the most abundant myeloid cell population in each of our untreated, Vk12598 transplanted mice. Alternatively, populations of cDC2, pDC, moDC, and monocytes lacking expression of MHC class II markers were fixtures for healthy controls while markedly less abundant in tumor-bearing mice. Tumor burdens in three samples subjected to LCL161 therapy were significantly reduced 24-hours post treatment and accompanied by an expansion of late-stage neutrophils and migratory DCs with expression features mirroring those of DCs from mesenteric lymph nodes. This composition of immune cells was distinct from all other sample including those treated with cyclophosphamide or bortezomib. In addition, relative proportions of B, T, and NK cells were nearly fully reconstituted, matching levels observed in healthy controls, in two of these samples. In a direct functional assessment, expression levels of Fscn1 and Ccr7 (key over-expressed genes in these migratory DCs) markedly increased following treatment of bone marrow derived DCs with LCL161. Overall, the transcriptional profile of these migratory DCs indicates their pivotal role in maturation of DCs (Fscn1, Tmem123) as well as the recruitment of T and NKT cells (Cxcl16, Ccr7) and increase in antigen presentation (Cd63)–all of which may serve to ‘warm' tumors, increasing T cell infiltration necessary for immunotherapy approaches. With the increased resolution of scRNA-seq, we observe unique alterations in the composition of the immune microenvironment of MM induced by treatment with LCL161 that further detail its unique mechanism of anti-MM activity. Citation Format: Caleb K. Stein, Erin Meermeier, Seth Welsh, Victoria Garbitt, Meaghen Sharik, P. Leif Bergsagel, Nicholas Banovich, Jonathan Keats, Marta Chesi. scRNA-seq reveals restructuring of the immune microenvironment of multiple myeloma following treatment with an IAP antagonist [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 5622.

Corneal Epithelial Findings in Patients with Multiple Myeloma Treated with Antibody-Drug Conjugate Belantamab Mafodotin in the Pivotal, Randomized, DREAMM-2 Study.

IntroductionPatients with relapsed or refractory multiple myeloma (RRMM) represent an unmet clinical need. Belantamab mafodotin (belamaf; GSK2857916) is a first-in-class antibody–drug conjugate (ADC; or immunoconjugate) that delivers a cytotoxic payload, monomethyl auristatin F (MMAF), to myeloma cells. In the phase II DREAMM-2 study (NCT03525678), single-agent belamaf (2.5 mg/kg) demonstrated clinically meaningful anti-myeloma activity (overall response rate 32%) in patients with heavily pretreated disease. Microcyst-like epithelial changes (MECs) were common, consistent with reports from other MMAF-containing ADCs.MethodsCorneal examination findings from patients in DREAMM-2 were reviewed, and the clinical descriptions and accompanying images (slit lamp microscopy and in vivo confocal microscopy [IVCM]) of representative events were selected. A literature review on corneal events reported with other ADCs was performed.ResultsIn most patients receiving single-agent belamaf (72%; 68/95), MECs were observed by slit lamp microscopy early in treatment (69% had their first event by dose 4). However, IVCM revealed hyperreflective material. Blurred vision (25%) and dry eye (15%) were commonly reported symptoms. Management of MECs included dose delays (47%)/reductions (25%), with few patients discontinuing due to MECs (1%). The first event resolved in most patients (grade ≥2 MECs and visual acuity [each 77%], blurred vision [67%], and dry eye [86%]), with no reports of permanent vision loss to date. A literature review confirmed that similar MECs were reported with other ADCs; however, event management strategies varied. The pathophysiology of MECs is unclear, though the ADC cytotoxic payload may contribute to on- or off-target effects on corneal epithelial cells.ConclusionSingle-agent belamaf represents a new treatment option for patients with RRMM. As with other ADCs, MECs were observed and additional research is warranted to determine their pathophysiology. A multidisciplinary approach, involving close collaboration between eye care professionals and hematologist/oncologists, is needed to determine appropriate diagnosis and management of these patients.Trial RegistrationClinicalTrials.gov Identifier, NCT03525678.

The novel protein homeostatic modulator BTX306 is active in myeloma and overcomes bortezomib and lenalidomide resistance.

Small molecules targeting the cereblon-containing E3 ubiquitin ligase including thalidomide, lenalidomide, and pomalidomide modulate turnover of downstream client proteins and demonstrate pre-clinical and clinical anti-myeloma activity. Different drugs that engage with cereblon hold the potential of unique phenotypic effects, and we therefore studied the novel protein homeostatic modulator (PHM™) BTX306 with a unique thiophene-fused scaffold bearing a substituted phenylurea and glutarimide. This agent much more potently reduced human-derived myeloma cell line viability, with median inhibitory concentrations in the single nanomolar range versus micromolar values for lenalidomide or pomalidomide, and more potently activated caspases 3/8/9. While lenalidomide and pomalidomide induced greater degradation of Ikaros and Aiolos in myeloma cells, BTX306 more potently reduced levels of GSPT1, eRF1, CK1α, MCL-1, and c-MYC. Suppression of cereblon or overexpression of Aiolos or Ikaros induced relative resistance to BTX306, and this agent did not impact viability of murine hematopoietic cells in an in vivo model, demonstrating its specificity for human cereblon. Interestingly, BTX306 did show some reduced activity in lenalidomide-resistant cell line models but nonetheless retained its nanomolar potency in vitro, overcame bortezomib resistance, and was equipotent against otherwise isogenic cell line models with either wild-type or knockout TP53. Finally, BTX306 demonstrated strong activity against primary CD138-positive plasma cells, showed enhanced anti-proliferative activity in combination with bortezomib and dexamethasone, and was effective in an in vivo systemic model of multiple myeloma. Taken together, the data support further translational studies of BTX306 and its derivatives to the clinic for patients with relapsed and/or refractory myeloma. KEY MESSAGES: BTX306 has a unique thiophene-fused scaffold bearing phenylurea and glutarimide. BTX306 is more potent against myeloma cells than lenalidomide or pomalidomide. BTX306 overcomes myeloma cell resistance to lenalidomide or bortezomib in vitro. BTX306 is active against primary myeloma cells, and shows efficacy in vivo.

4473 Immune control of plasma cell disorders – in-depth analysis of Sox2 immunity in MGUS

OBJECTIVES/GOALS: We aim to identify and characterize anti-Sox2-specific CD8+ T cell responses in stable MUGS patients expressing HLA class I alleles-A*02:01 and /or -B*07:02. METHODS/STUDY POPULATION: Cross sectional study of patients with stable MGUS defined as stable serum paraprotein for ≥ 12 months from the MM Research Clinic at the Abramson Cancer Institute. Sox2 T cell reactivity will be assessed by IFN-γ ELISPOT assays. Rested PBMC will be pulsed with candidate Sox2-derived peptides predicted to display high affinity to HLA class I alleles and known to be processed and presented as determined by “targeted MS/MS” (mass spectrometry). The presence of anti-Sox2-specific CD8+ T cells will be confirmed in peptide/HLA multimer assays using flow cytometry. Anti-Sox2-specific CD8+ T cells will be characterized for HLA restriction and TCR αβ composition. RESULTS/ANTICIPATED RESULTS: Our work is still in progress. From Aug to Dec 2019, 22 MGUS subjects have been analyzed, 11 of which were found to have the HLA of interest. Positive Sox-2 reactivity by ELISpot was found in 3 subjects. DISCUSSION/SIGNIFICANCE OF IMPACT: Anti-Sox2 immune responses may maintain MGUS in a clinical indolent state by eliminating Sox2-expressing clonogenic MM cells. A detailed characterization of anti-Sox2 T cells followed by in-vivo assessment of their anti-myeloma activity could provide the foundation for a Sox2 based immunotherapy approach in MM.

DREAMM-9: Phase III study of belantamab mafodotin plus VRd versus VRd alone in transplant-ineligible newly diagnosed multiple myeloma (TI NDMM).

TPS8556 Background: Bortezomib, lenalidomide, and dexamethasone (VRd) is the standard of care for transplant-eligible and TI NDMM, but relapse is usually inevitable. The median progression-free survival (PFS) is ~3 years for patients with TI NDMM, and with each relapse, the duration of response (DoR) diminishes, highlighting the need for novel, effective, targeted agents. Single-agent belantamab mafodotin is a first-in-class B-cell maturation antigen–binding, humanized, afucosylated, monoclonal immunoconjugate, showing deep and durable responses in heavily pretreated patients with relapsed/refractory multiple myeloma ( Lancet Oncol2020). Preclinical work suggests belantamab mafodotin plus bortezomib or lenalidomide enhances anti-myeloma activity. Therefore, studying clinical activity of belantamab mafodotin in combination with these agents is warranted. Methods: DREAMM-9 (NCT04091126) is a two-part, open-label study to determine efficacy and safety of single-agent belantamab mafodotin with VRd vs. VRd alone in patients with TI NDMM. Patients aged ≥18 years with ECOG status 0–2 and adequate organ system functions will be eligible. Part 1 (dose selection) will evaluate safety/tolerability of belantamab mafodotin with VRd administered by single (Day 1) or split dosing (Days 1 and 8) in ≤5 cohorts (n = 12/cohort): 1.9 mg/kg, 2.5 mg/kg split and single, and 3.4 mg/kg split and single. Six more patients may be added to cohort(s) most likely to be selected as recommended Phase III dose (RP3D). Dose-limiting toxicities and adverse events (AEs) will be assessed, and belantamab mafodotin RP3D determined through modified toxicity probability interval criteria. Part 2 (randomized Phase III) will determine efficacy and safety of belantamab mafodotin at RP3D with VRd vs. VRd alone (n = 750) in two arms randomized 1:1. Dual primary endpoints will be rate of minimal residual disease (MRD) negativity and PFS. Secondary endpoints will be response rates (overall response, complete response, very good partial response or better, sustained MRD negativity), DoR, time to progression, and overall survival. Safety assessment will include AEs, serious AEs and ocular findings. In both parts, belantamab mafodotin will be given with VRd for eight induction cycles and then with Rd for maintenance until disease progression or unacceptable toxicity. Funding: GlaxoSmithKline (209664). Drug linker technology licensed from Seattle Genetics; monoclonal antibody produced using POTELLIGENT Technology licensed from BioWa. Clinical trial information: NCT04091126 .

Updated analysis of a phase I/II study of venetoclax in combination with daratumumab and dexamethasone, +/- bortezomib, in patients with relapsed/refractory multiple myeloma.

8511 Background: Venetoclax (Ven) is a selective, potent, oral BCL-2 inhibitor that induces apoptosis in multiple myeloma (MM) cells in vitro. It has shown synergistic activity with bortezomib (V) and dexamethasone (d). Combination of the CD38 monoclonal antibody daratumumab (D) with Ven is hypothesized to further increase anti-myeloma activity based on dual mechanisms of pro-apoptotic effects on tumor cells and enhanced immune stimulation. Methods: This ongoing Phase 1/2, nonrandomized, multicenter study (NCT03314181) is evaluating safety, efficacy and pharmacokinetics (PK) of VenDd +/- V in patients (pts) with relapsed/refractory MM. In Part 1, pts with t(11;14) who received ≥1 prior line of therapy (PI and an immunomodulatory drug) were treated with VenDd [Ven QD + D 16 mg/kg IV + d 40 mg weekly]. In Part 2, pts irrespective of t(11;14) status, non-refractory to PIs and who received 1–3 prior lines of therapy were treated with VenDVd [Ven QD + D 16 mg/kg IV + V (1.3 mg/m2) + d (20 mg)]. A randomized, open-label expansion (Part 3) will further evaluate and compare safety and efficacy of VenDd (400 or 800 mg Ven dose levels) with control DVd in pts with t(11;14). Results: As of Dec 05, 2019, 48 pts were enrolled. Part 1 included 24 pts with t(11;14), median age 63 (range 51–76). Part 2 included 24 pts, median age 65 (range 41–80) of which 6 (25%) had t(11;14). Frequent adverse events (AEs; VenDd/VenDVd) were fatigue (71%/25%), diarrhea (58%/46%), nausea (46%/50%), insomnia (33%/50%), upper respiratory tract infection (33%/21%), cough (42%/9%), and dyspnea (25%/25%). Frequent Grade ≥ 3 AEs in pts on VenDd were neutropenia (17%), hypertension (12%), fatigue and hyperglycemia (8% each), and in pts on VenDVd were insomnia (21%), diarrhea and thrombocytopenia (8% each). Nine pts had infection-related Grade ≥ 3 AEs (5 VenDd, 4 VenDVd). Eighteen pts had a serious AE (11 VenDd, 7 VenDVd) with pyrexia (n = 3) being most common. One pt on VenDVd died of progressive disease. PK analyses showed that addition of D and V did not impact Ven exposure. Median follow-up time (VenDd/VenDVd) was 10 and 9 months. Overall response rate in VenDd/VenDVd was 96%/92% and 96%/79% had ≥ very good partial response rate. Median progression free survival and duration of response were not reached. Conclusions: Pts treated with VenDd +/- V continue to demonstrate a tolerable safety profile with encouraging efficacy, notably among pts with t(11;14) treated with VenDd. Safety, efficacy, PK, and cytogenetics analyses will be updated for presentation. Clinical trial information: NCT03314181 .

DREAMM-5 platform trial: Belantamab mafodotin in combination with novel agents in patients with relapsed/refractory multiple myeloma (RRMM).

TPS8552 Background: Single-agent belantamab mafodotin (GSK2857916), a B-cell maturation antigen targeting immunoconjugate, induced deep and durable responses in patients with RRMM, with a manageable safety profile (DREAMM-2, NCT03525678, Lancet Oncol.2020). A platform trial design allows efficient evaluation of belantamab mafodotin in combination with other anti-myeloma agents, such as a humanized wild-type IgG1 anti-OX40 agonist, an IgG4 inducible T-cell costimulatory (ICOS) agonist, and a gamma-secretase inhibitor. The unique, multimodal mechanisms of action (MoAs) of belantamab mafodotin, in combination with MoAs of these agents, has the potential to achieve synergistic effects in MM, to further enhance anti-myeloma activity without compromising safety. Methods: DREAMM-5 (NCT04162210) utilizes a master protocol with separate sub-studies comprised of sequential dose exploration (DE) and cohort expansion (CE) phases, to identify promising, effective belantamab mafodotin combinations when compared with a shared belantamab mafodotin monotherapy control arm (CE phase only). DE phases consist of multiple dosing cohorts with belantamab mafodotin combinations where patients are assigned to treatment slots by predetermined algorithmic approach (modified toxicity probability interval; N≤10 per cohort). Recommended phase 2 doses (RP2D) will be based on dose-limiting toxicities, safety, and pharmacokinetics. Interim analyses, based on overall response rate (ORR), determine if a RP2D is moved forward to a CE phase (N≥35 per cohort). Patients in the CE (stratified by number of prior therapies) will be randomized equally to open sub-studies. Eligible patients will have received ≥3 prior therapy lines which must include ≥1 immunomodulatory agent, proteasome inhibitor, and anti-CD38 antibody. The primary objectives are to identify RP2D for each combination (DE phase) and ORR (≥partial response, CE phase). Sub-studies 1 (combination with GSK3174998, OX40 agonist antibody) and 2 (combination with GSK3359609, ICOS agonist antibody) are currently enrolling. Sub-study 3 (combination with nirogacestat [PF-03084014; SpringWorks Therapeutics]) is projected to begin enrollment in the first half of 2020. Additional sub-studies will be explored based on scientific rationale and/or preclinical combination study results. Funding: GlaxoSmithKline (207495). Drug linker technology licensed from Seattle Genetics; monoclonal antibody produced using POTELLIGENT Technology licensed from BioWa. Clinical trial information: NCT04162210 .

BCMA-targeting Bispecific Antibody That Simultaneously Stimulates NKG2D-enhanced Efficacy Against Multiple Myeloma.

B-cell maturation antigen (BCMA) is a highly plasma cell-selective protein expressed on malignant plasma cells of patients with multiple myeloma (MM), and it is a defined therapeutic target. Major histocompatibility complex class I-related chain A (MICA) is frequently expressed in lymphoproliferative malignancies including MM. MICA activates natural killer (NK) cells and costimulates T cells by interaction with its immunoreceptor NK cell receptor G2D (NKG2D). Nonetheless, during full-blown MM, tumor cells promote efficient MICA shedding, which evokes NKG2D internalization and immune suppression. To enhance the directional killing efficacy of immune cells against myeloma cells, we constructed a novel bispecific antibody 2A9-MICA and explored its potential antimyeloma activity against MM. 2A9-MICA consists of human MICA extracellular region and a single-chain antibody fragment (scFv) that targets BCMA generated by phage display technology. In vitro, 2A9-MICA activated NK cell-mediated cytotoxicity and induced NK cells to kill BCMA-positive human myeloma cells. Moreover, in BCMA-positive, MM-bearing nude mice, 2A9-MICA specifically targeted tumor tissue, where it effectively recruited immune cells and inhibited tumor tissue growth showed superior antitumor activity. Taken together, bispecific antibody 2A9-MICA provides a new approach for MM-targeting immunotherapy and has attractive potential for clinical applications.

Chidamide epigenetically represses autophagy and exerts cooperative antimyeloma activity with bortezomib

Autophagy and ubiquitin proteasome system are two distinct and cooperative proteolytic pathways. The dual-pathway suppression represents a promising therapeutic strategy for multiple myeloma. Chidamide is a novel benzamide inhibitor of histone deacetylase, and shows potent antimyeloma activity. Here, we revealed the autophagy-suppressive role of chidamide in myeloma cells. We then demonstrated that chidamide treatment markedly downregulated histone deacetylase SIRT1, and simultaneously resulted in dose-dependent upregulation of acetyltransferase hMOF and histone methyltransferase EZH2, which contributed to an increase in global levels of histone H4 lysine 16 acetylation (H4k16ac) and histone H3 lysine 27 trimethylation (H3k27me3). We next confirmed concomitant upregulation of H4k16ac and H3k27me3 in the same promoter regions of the autophagy-related gene LC3B, reinforcing the specific roles for H4k16ac and H3k27me3 in mediating chidamide-induced transcriptional repression of LC3B. Finally, we provided experimental evidence that co-treatment with chidamide and proteasome inhibitor bortezomib induced clear synergistic cytotoxicity against MM cells, which was associated with increased accumulation of ubiquitinated proteins and excessive endoplasmic reticulum stress or dysregulated unfolded protein response. Our results altogether suggest that chidamide cooperatively potentiates antimyeloma activity of bortezomib, at least in part, by epigenetically repressing autophagic degradation of ubiquitinated proteins.

CDK5 inhibition invitro and in vivo induces cell death inmyeloma and overcomes the obstacle of bortezomib resistance.

The emergence of new drugs is a major feature of the treatment history of multiple myeloma (MM), which also reflects the current incurability of MM. As a unique member of cyclin dependent kinase (CDK) family, CDK5 participates in numerous tumorigenic or non-tumorigenic processes. The aim of this study is to investigate the effects of CDK5 on the viability of MM cells and bortezomib resistance using western blotting, immunohistochemistry, transient transfection, MTT assays, cell cycle analysis, apoptosis assays and a myeloma xenograft mouse model. The present study found that MM patients with high CDK5 expression in the bone marrow do not respond well to bortezomib, have higher DS stage and worse prognosis. Genetic and pharmacological (dinaciclib) inhibition of CDK5 triggers MM cell viability inhibition. Dinaciclib induces G2/M arrest and apoptosis of MM cells. In vivo experiments with myeloma xenograft mice indicate that dinaciclib significantly reduces the volume of tumors with good tolerance. Dinaciclib combined with bortezomib exerts a synergistic anti-myeloma activity accompanied by inhibiting the activation of the nuclear factor-κB pathway. This study demonstrates the important role of CDK5 in the pathogenesis, viability, prognosis and resistance to bortezomib of MM, laying a solid theoretical foundation for further clinical use of CDK5 inhibitors.

Novel conjugates of endoperoxide and 4-anilinoquinazoline induce myeloma cell apoptosis by inhibiting the IGF1-R/AKT/mTOR signaling pathway.

4-anilinoquinazoline-containing inhibitors of the epidermal growth factor receptor (EGFR) are widely used in non-small cell lung cancer patients with mutated EGFR, but they are less effective in multiple myeloma (MM), a fatal malignancy derived from plasma cells. The present study designed a series of novel compounds by conjugating a peroxide bridge to the 4-anilinoquinazoline pharmacophore. Further studies showed that these agents such as 4061 and 4065B displayed potent activity to induce MM cell apoptosis by upregulating pro-apoptotic p53 and Bax while downregulating pro-survival Bcl-2. The mechanistic analysis revealed that both 4061 and 4065B inhibited IGF1-R, AKT and mTOR activation in a concentration dependent manner but had no effects on the expression of their total proteins, suggesting the conjugates of endoperoxide and 4-anilinoquinazoline may exert its anti-myeloma activity by targeting the IGF1-R/AKT/mTOR pathway.

A novel phosphoramide compound, DCZ0847, displays in vitro and in vivo anti-myeloma activity, alone or in combination with bortezomib.

Multiple myeloma (MM) is an incurable hematological malignancy, for which novel effective therapies are urgently needed. We synthesized a novel phosphoramide compound, DCZ0847, showing a potent anti-myeloma activity both in vitro and in vivo. DCZ0847 showed high cytotoxicity towards primary MM cells but had no effect on normal cells and was well tolerated in vivo. The anti-myeloma activity of DCZ0847 was associated with inhibition of cell proliferation; promotion of cell apoptosis via mitochondrial transmembrane potential collapse and caspase-mediated extrinsic or intrinsic apoptotic pathways; and the induction of G2/M phase arrest via downregulation of CDC25C, CDK1, and cyclin B1. In particular, DCZ0847 induced DNA damage and triggered a DNA-damage response by enhancing the levels of γ-H2A.X, phosphorylated (p)-ATM, p-ATR, p-Chk1, and p-Chk2. Additionally, DCZ0847 was able to overcome the bone marrow stromal cells-induced proliferation of MM cells and blocked JAK2/STAT3 signaling. Importantly, DCZ0847 acted synergistically with bortezomib, with the combination exerting greater cytotoxic effects in vitro and in vivo. Together, our results indicate that DCZ0847, alone or in combination with bortezomib, may represent a potential new therapy for patients with MM.

Disulfiram/copper markedly induced myeloma cell apoptosis through activation of JNK and intrinsic and extrinsic apoptosis pathways

Disulfiram (DSF) is an FDA approved anti-alcoholism drug in use for more than 60 years. Recently, antitumor activity of the DSF/copper (DSF/Cu) complex has been identified. Its anti-multiple myeloma activity, however, has barely been investigated. In the present study, our results demonstrated that the DSF/Cu complex induced apoptosis of MM cells and MM primary cells. The results indicated that DSF/Cu significantly induced cell cycle arrest at the G2/M phase in MM.1S and RPMI8226 cells. Moreover, JC-1 and Western blot results showed that DSF/Cu disrupted mitochondrial membrane integrity and cleaved caspase-8 in MM cells, respectively, suggesting that it induced activation of extrinsic and intrinsic apoptosis pathways. Interestingly, DSF/Cu induced caspase-3 activation was partly blocked by Z-VAD-FMK (zVAD), a pan-caspase inhibitor, indicating at caspase-dependent and -independent paths involved in DSF/Cu induced myeloma cell apoptosis machinery. Additionally, activation of the c-Jun N-terminal kinase (JNK) signaling pathway was observed in DSF/Cu treated MM cells. More importantly, our results demonstrated that DSF/Cu significantly reduced tumor volumes and prolonged overall survival of MM bearing mice when compared with the controls. Taken together, our novel findings showed that DSF/Cu has potent anti-myeloma activity in vitro and in vivo highlighting valuable clinical potential of DSF/Cu in MM treatment.

Genome-wide screening reveals a role for subcellular localization of CRBN in the anti-myeloma activity of pomalidomide

Pomalidomide, a derivative of thalidomide, is an effective treatment for multiple myeloma. The drug exerts its effects through CRBN, a component of the E3 ubiquitin ligase complex CRL4CRBN. To search for novel factors involved in the anti-cancer activity of pomalidomide, we performed a genome-wide shRNA library screen and identified 445 genes as those affecting pomalidomide sensitivity. Genes encoding components of the ubiquitin-proteasome pathway, such as subunits of the CRL4CRBN complex, the COP9 signalosome, and the 26S proteasome, were among the pomalidomide-affecting genes. Karyopherin beta 1 (KPNB1) was identified as a novel pomalidomide-affecting gene. KPNB1 was required for the nuclear import of CRBN and for the CRBN-directed, pomalidomide-dependent degradation of a clinically relevant substrate, the transcription factor Aiolos. By contrast, the cytoplasmic translation factor GSPT1 was degraded following treatment with the thalidomide derivative CC-885 only when CRBN was present in the cytoplasm, indicating that subcellular distribution of CRBN is critical for the efficacy of thalidomide-based medications.