We analyzed the efficacy and safety of selinexor-containing triplet regimens (selinexor-bortezomib-dexamethasone, selinexor-pomalidomide-dexamethasone, and selinexor-carfilzomib-dexamethasone) in a subset of STOMP and BOSTON study patients (n = 62) with multiple myeloma enrolled after a median of 4 prior lines, which included an anti-CD38 monoclonal antibodies-containing regimen. The results suggest that selinexor-containing triplets may provide prolonged disease control with generally acceptable tolerability in these patients.Background: The increasing use of anti-CD38 monoclonal antibodies (alpha CD38 mAbs) for newly diagnosed or early relapsed multiple myeloma (MM), especially in non-transplant eligible patients, may lead to more patients developing alpha CD38 mAb-refractory disease earlier in the treatment course with fewer treatment options. Patients and methods: We analyzed the efficacy and safety of selinexor-based triplets (selinexor +dexamethasone [Sd] plus pomalidomide [SPd, n = 23], bortezomib [SVd, n = 16] or carfilzomib (SKd, n = 23]) in a subset of STOMP (NCT02343042) and BOSTON (NCT03110562) study patients treated previously with alpha CD38 mAbs. Results: Sixty-two patients (median 4 prior therapies, range 1 to 11, 90.3% refractory to alpha CD38 mAb) were included. Overall response rates (ORR) in the SPd, SVd and SKd cohorts were 52.2%, 56.3%, and 65.2%, respectively. Overall response rate was 47.4% among patients who had MM refractory to the third drug reintroduced in the Sd-based triplet. Median progression-free survival in the SPd, SVd, and SKd cohorts was 8.7, 6.7, and 15.0 months, respectively, and median overall survival was 9.6, 16.9, and 33.0 months, respectively. Median time to discontinuation in the SPd, SVd, and SKd cohorts was 4.4, 5.9, and 10.6 months, respectively. The most common hematological adverse events were thrombocytopenia, anemia, and neutropenia. Nausea, fatigue, and diarrhea were pr imar ily grade 1/2. Adverse events were generally manageable with standard supportive care and dose modifications. Conclusion: Selinexor-based regimens may offer effective and well -tolerated therapy to patients with relapsed and/or refractory MM who had disease previously exposed or refractory to alpha CD38 mAb therapy and could help address the unmet clinical need in these high-risk patients.

PDF - 156K, Supplementary Figure 1, demonstrating CD38 receptor surface stability. Supplementary Figure 2, demonstrating animal body weight following anti-CD38 pretargeted radioimmunotherapy. Supplemental methods describing fusion protein construction as well as endocytosis and trichloroacetic acid (TCA) precipitation assays.

Background: Despite recent advances, multiple myeloma (MM) remains incurable and becomes refractory to immunomodulatory drugs (IMiDs), proteasome inhibitors (PIs) and anti-CD38 monoclonal antibodies (anti-CD38 mAbs). The prognosis of patients with triple-class refractory MM (TCR MM) is poor because of limited alternate therapies. The increasing number of patients with TCR MM leaves an unmet need for effective treatments in this population. The oral exportin-1 inhibitor selinexor has a novel mechanism of action by blocking nuclear export, which leads to accumulation of tumor suppressor proteins in the nucleus and blockage of protein translation of oncogenes. Selinexor is indicated for treatment of relapsed/refractory MM (RRMM) in combination with either dexamethasone (Xd) or bortezomib and dexamethasone (XVd). Approval of the QW regimen of selinexor, bortezomib and dexamethasone (XVd) was based on the BOSTON study (NCT03110562), in which 195 patients receiving XVd had a median progression free survival (mPFS) of 13.93 months vs 9.46 months in 207 patients who received twice-weekly Vd. Results from previous studies in RRMM (STOMP phase 1/2 Study NCT02343042; phase 1 Study NCT02199665) confirmed that a combination of QW Xd with another PI, carfilzomib, is associated with impressive efficacy, an overall response rate (ORR) of 78%, including in patients with TCR MM (ORR = 67%) and patients with carfilzomib-refractory MM (ORR = 62%). The long mPFS, extending over a year, including in TCR MM, indicates selinexor-containing regimens provide prolonged disease control with good tolerability. Based on those results, we investigated XKd in a subset of STOMP patients with TCR MM with the aim of further exploring the tolerability of XKd in this patient population. Methods: The STOMP study XKd arm enrolled patients ≥18 years of age with RRMM. Patients were administered the QW combination of oral selinexor (60-100 mg), dexamethasone 40 mg, and IV carfilzomib 56-70 mg/m2. Treatment-emergent adverse events (TEAEs) were used to assess safety and tolerability. Efficacy endpoints included ORR, duration of response (DOR), PFS, overall survival (OS), and time to response (TTR). Results: Of the 33 patients treated with XKd, 23 had triple-class treated (TCT) MM. Twelve had TCR MM, including 8 (66.7%) with high-risk cytogenetics del(17p), t(4;14), t(14;16) and/or gain 1q. The median age of patients with TCR MM was 67 and the median number of previous lines of therapy was 4 (range, 2-8) (Table 1). The rate of TEAEs in the patients with TCR MM was comparable to rates in the full cohort and the TCT subgroup (Table 2). Common hematologic TEAEs included thrombocytopenia (83.3%) and anemia (58.3%). Non-hematologic AEs included nausea (100%), decreased appetite (58.3%), and fatigue (58.3%). All cases of fatigue and all but a single event of nausea and decreased appetite had a severity grade of ≤2, and these low grade TEAEs were largely reversible and manageable with supportive care and dose modifications. Two patients discontinued study treatment after 149 and 386 days due to TEAEs, specifically cardiac toxicity attributed to carfilzomib (56 mg/m2 QW). There were no deaths due to TEAEs. The ORR was 66.7% (95% CI, 34.9-90.1), including 5 (41.7%) very good partial responses and 1 (8.3%) complete response. Median DOR was 12.0 months (95% CI, 12.0-not estimable [NE]). Median PFS was 13.8 months (95% CI, 5.3-NE) and median OS was 33 months (95% CI, 20.4-NE). Median TTR was 1 month (95% CI, 0.9-NE). In TCT MM, results were similar with an ORR of 65.2% and median PFS of 14.3 months (95% CI 12.0-NE). Tolerability is evidenced by the duration of study treatment of more than 6 months in 58.3% of patients and median time to discontinuation of 7.1 months (95% CI 4.6-NE). The median weekly selinexor dose was 60.8 mg. Conclusions: Despite a small sample size, these results highlight the potential utility of XKd as a treatment regimen for patients with TCR MM. XKd was generally well tolerated in this patient population with a generally manageable AE profile and a median DOR of 12 months. These results compare favorably to that found in the MAMMOTH study, where patients previously treated with anti-CD38 mAbs who primarily had TCR MM experienced an ORR of 31% and mPFS of 3.4 months when treated with standard treatment regimens. Interestingly, in MAMMOTH, the best ORR (47%) and mPFS (5.7 months) were observed in patients treated with carfilzomib-alkylator combinations. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

REGN5458 shows early, deep, and durable responses with a manageable safety profile in triple or greater-refractory patients with RRMM. This study is funded by Regeneron.

In the primary analysis of LYRA, daratumumab + cyclophosphamide/bortezomib/dexamethasone (DARA + CyBorD) was effective and well tolerated in newly diagnosed multiple myeloma (NDMM) and relapsed multiple myeloma (RMM). We report the final analysis of LYRA (median months of follow-up: NDMM, 35.7; RMM, 35.3) after all patients completed study therapy, were followed for 36 months, or discontinued. Patients received DARA + CyBorD induction, autologous stem cell transplant (if eligible), and 12 months of daratumumab maintenance. Eighty-seven NDMM patients enrolled, 39 underwent transplant, and 63 completed maintenance. Rates of complete response or better were 48.7% and 29.8% for NDMM transplant and NDMM non-transplant patients, respectively, and 36-month progression-free survival rates were 69.3% and 72.6%. Grade 3/4 treatment-emergent adverse events occurred in 61.6% of NDMM patients. Efficacy and safety data are also reported for the smaller RMM cohort (n = 14). DARA + CyBorD followed by daratumumab maintenance was well tolerated and achieved deep, durable responses in NDMM and RMM.

There is a lack of consensus on therapy sequencing in previously treated multiple myeloma, particularly after anti-B-cell maturation antigen (BCMA) therapy. Earlier reports on selinexor (X) regimens demonstrated considerable efficacy in early treatment, and after anti-BCMA-targeted chimeric antigen receptor-T cell therapy. Here, we present data from 11 heavily pretreated patients who predominantly received BCMA-antibody-drug conjugate therapy. We observe that X-containing regimens are potent and achieve durable responses with numerically higher overall response and clinical benefit rates, as well as median progression free survival compared to patients' prior anti-BCMA therapies, despite being used later in the treatment course. In an area of evolving unmet need, these data reaffirm the efficacy of X-based regimens following broader anti-BCMA therapy.

Background: Patients with relapsed/refractory (R/R) diffuse large B-cell lymphoma (DLBCL) often have a poor prognosis despite therapies using second-line chemoimmunotherapy (CIT). Achievement of complete response (CR) with second-line therapy is associated with improved long-term outcomes. Unfortunately, only 25-35% of patients achieve CR with standard CIT regimens alone. The addition of novel targeted agents such as Bruton Tyrosine Kinase inhibitors (BTKi) to second-line therapy may offer improved treatment responses given the importance of B-cell receptor (BCR) signaling in DLBCL. BTK has been shown to be essential for BCR-mediated activation of the NF- κB/Rel family of transcription factors and BCR signaling has been recognized as a key pathway in the pathogenesis of DLBCL. Moreover, NF-κB activity relies upon chronic active BCR signaling in activated B-cell-like DLBCL, which can be potentially blocked by kinase inhibitors targeting BTK. In this study we examine the feasibility and efficacy of adding the BTKi, acalabrutinib (A), to standard second-line therapy to improve disease response in patients with R/R DLBCL. Here we present initial safety and tolerability data for the ongoing study.

Abstract Introduction: Despite the availability of many effective agents, multiple myeloma is characterized by repeated cycles of treatment response and relapse, and remains incurable in almost all patients. Efforts to optimize treatment are complicated by variation in disease biology and by the combinatorial complexity inherent in assembling, sequencing and administering multi-agent regimens. Determining which strategies provide maximal therapeutic benefit requires deploying a variety of multi-agent regimens in a range of settings and assessing long-term outcomes; information that cannot be readily discerned from clinical trials. Here we present results from a real-world database that comprehensively tracks all treatments and responses in patients with multiple myeloma. Methods: Since March 2017, All4Cure has hosted an online platform for patients with multiple myeloma, clinicians and researchers that has been initially focused in the Pacific Northwest. Medical records from consenting patients are collected and information regarding all treatments and responses graphically displayed on their de-identified dashboards. A discussion panel allows for asynchronous communication between members of All4Cure's community of patients, clinicians and researchers (currently numbering over 1600 participants). There is no charge to patients who participate in All4Cure, and clinicians and researchers are neither charged nor paid for their participation. A summarized real-world database describes the lines of therapy that each patient has received, treatment start and stop dates, and responses in accordance with International Myeloma Working Group (IMWG) criteria. Results: The overall profile of patients with multiple myeloma enrolled in All4Cure (N=555) was benchmarked against myeloma patients from the National Program of Cancer Registries (NPCR) (diagnosis year 2017; N=25,895). Patients in all 50 States and D.C. were included in the comparison, and those with monoclonal gammopathy of undetermined significance (MGUS) were not considered. Myeloma patients enrolled in All4Cure are younger at diagnosis or start of treatment (median 61 versus between 65 and 69), more likely to be white (90.3% versus 73.5%), and more likely to reside in Washington State (41.2% versus 2%) compared to the NPCR cohort, reflecting participation influenced by geographic location as described above. After enrollment, All4Cure patients are followed longitudinally throughout the entirety of their disease course, with fewer than 2% having been lost to follow up. To gain insights uniquely available from the All4Cure database and to inform the future direction for our research, we focus our exploratory data analysis on the All4Cure cohort of patients who started treatment in June 2015 or later (N=299). Despite the relatively recent start of the All4Cure database, this timeframe allows up to 6 years of observation following the start of treatment, since the survival rates for the first 1-2 years of treatment are generally very high. Consistent with prior knowledge, increasing age and disease stage are associated with increased morality, as are high-risk cytogenetics such as 17p-, t(4:14) and t(14;16). We further explored the potential impact of early lines of therapy on long-term disease control. While the current literature is mixed on the merits of aggressive treatments in early lines of therapy in terms of overall survival, insights from our data suggest that more aggressive front-line therapies (such as SCT) are associated with improved disease control over time, although this is evolving with the impact of novel therapies and in particular the use of triplet and now quadruplet induction regimens and adapting treatment to achieve measurable residual disease (MRD) negativity. Conclusions: Even with the current limitations regarding the size and representativeness of All4Cure's database, these preliminary results support the validity of this approach for gaining insight into the treatments and outcomes of patients with multiple myeloma in real-world settings. Disclosures Blau: Oncopeptides: Other: Oncopeptides is an All4Cure customer. Blau: All4Cure: Current equity holder in publicly-traded company. Richter: Tisch Cancer Institute: Icahn School of Medicine at Mount Sinai: Current Employment; Janssen, Celgene: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Adaptive biotechnologies: Speakers Bureau; BMS, Karyopharm, Antengene: Membership on an entity's Board of Directors or advisory committees. Bensinger: BMS, Janssen, Poseida, Regeneron, Trillium: Research Funding; Amgen, BMS, Janssen, Sanofi: Speakers Bureau. Richardson: Secura Bio: Consultancy; Protocol Intelligence: Consultancy; Sanofi: Consultancy; Jazz Pharmaceuticals: Consultancy, Research Funding; AstraZeneca: Consultancy; Oncopeptides: Consultancy, Research Funding; AbbVie: Consultancy; GlaxoSmithKline: Consultancy; Regeneron: Consultancy; Janssen: Consultancy; Karyopharm: Consultancy, Research Funding; Celgene/BMS: Consultancy, Research Funding; Takeda: Consultancy, Research Funding. Anderson: Sanofi-Aventis: Membership on an entity's Board of Directors or advisory committees; Celgene: Membership on an entity's Board of Directors or advisory committees; Gilead: Membership on an entity's Board of Directors or advisory committees; Janssen: Membership on an entity's Board of Directors or advisory committees; Millenium-Takeda: Membership on an entity's Board of Directors or advisory committees; Bristol Myers Squibb: Membership on an entity's Board of Directors or advisory committees; Pfizer: Membership on an entity's Board of Directors or advisory committees; Scientific Founder of Oncopep and C4 Therapeutics: Current equity holder in publicly-traded company, Current holder of individual stocks in a privately-held company; AstraZeneca: Membership on an entity's Board of Directors or advisory committees; Mana Therapeutics: Membership on an entity's Board of Directors or advisory committees.

Background: Overexpression of the nuclear export protein exportin 1 (XPO1) mediates the functional inactivation of tumor suppressor proteins (TSPs), facilitates the export of oncogene mRNA thus facilitating oncoprotein expression, is associated with poor prognosis in multiple myeloma (MM), and contributes to immunomodulatory drug (IMiD) resistance. Selinexor is an oral, first-in-class, selective inhibitor of nuclear export (SINE) compound that by blocking XPO1 forces the nuclear retention and activation of TSPs and nuclear retention and inactivation of oncoproteins. 1 Selinexor is approved with low-dose dexamethasone ± bortezomib for patients with previously treated MM. Pomalidomide plus dexamethasone (Pd) has an overall response rate (ORR) of ~30% and median PFS (mPFS) of ~4 months in patients with MM refractory to bortezomib and lenalidomide. We hypothesized that selinexor could be safely combined with Pd (XPd) and would improve the combination's efficacy.

Abstract Background B cell maturation antigen (BCMA) is a clinically validated target for multiple myeloma (MM) based on its restricted expression profile and potential functional role in promoting MM cell survival. HPN217 is a BCMA-targeting T cell engager derived from the Harpoon Tri-specific T cell Activating Construct (TriTAC ®) platform. It is a recombinant polypeptide of approximately 50 kDa, engineered to be a small globular protein to enable efficient drug diffusion and exposure in tumor tissue and have a prolonged serum half-life at the same time. It contains three humanized antibody-derived binding domains, targeting BCMA for MM cell binding, albumin for half-life extension, and CD3ε for T cell engagement, activation, and cytolytic function differentiation. Methods The ongoing Phase 1 study initially evaluates escalating doses of once weekly IV administrations of HPN217 in patients with relapsed/refractory (R/R) MM who have received at least 3 prior therapies including a proteasome inhibitor, an immunomodulatory drug, and a CD38-targeted therapy. Prior exposure to BCMA-targeting agent is permitted for this initial part of the trial. Premedication to minimize cytokine release syndrome (CRS) includes dexamethasone, diphenhydramine, acetaminophen, and a proton pump inhibitor. Primary endpoints are safety, tolerability, and determination of maximum tolerated dose (MTD) and/or recommended phase two dose (RP2D). Secondary objectives are pharmacokinetics (PK), pharmacodynamics, immunogenicity, and preliminary anti-myeloma activity. Results As of July 5, 2021, 22 patients have been treated with HPN217 in 8 individual cohorts ranging from 5 to 2150 µg/week. Patients treated received a median of 8 (range of 4 - 16) prior systemic regimens, including 5 patients who received prior BCMA-targeted belantamab mafodotin or orvacabtagene autoleucel. No dose-limiting toxicities (DLTs) have been observed and MTD has not been reached. The most common treatment-emergent adverse events (TEAEs) are hematological changes including anemia, neutropenia, and thrombocytopenia. No CRS was observed in dose cohorts receiving 5 - 270 µg/week (n=7). CRS (Grade 1, 2) was observed in 4 of 15 patients receiving ≥810 µg/week. In one patient treated at 810 µg/week, transient elevated liver transaminases (Grade 4 AST and Grade 3 ALT) was observed. A second patient in the 270 µg/week cohort also showed Grade 1 AST increase. All CRS events and liver enzyme increases resolved, and all patients were successfully re-treated with escalating doses. HPN217 demonstrated a dose proportional increase in Cmax and AUC with a median serum half-life of 74 hours (range of 38 - 197 hours), confirming half-life extension. Half-life, clearance rate, and volume of distribution were dose-independent, suggesting linear PK kinetics. Pharmacodynamic analysis shows a dose-dependent, transient increases in serum cytokines and chemokines (e.g., IL-6, IL-8, IL-10, TNFα). A transient reduction in circulating T lymphocytes accompanied by upregulation of the activation markers CD25 and CD69 were also observed. Patient response to treatment will be reported. Conclusions HPN217 represents a novel half-life extended BCMA-targeting T cell engager that can be safely administered to patients with R/R MM at a dose of up to 2150 µg weekly. TEAEs have been transient and manageable. Transient serum cytokine/chemokine increase, T cell margination and upregulation of T cell activation markers, indicate target engagement of BCMA on plasma cells and CD3 on T cells, respectively, supporting the proposed mechanism of action for HPN217. Dose escalation, including implementation of step dosing, with the goal of establishing an RP2D regimen, is ongoing. NCT04184050 Disclosures Madan: Sanofi: Consultancy, Research Funding; GSK: Consultancy, Speakers Bureau; Amgen: Consultancy, Speakers Bureau; Karyopharm: Research Funding, Speakers Bureau; Takeda: Speakers Bureau; BMS: Consultancy, Speakers Bureau; Janssen: Consultancy, Speakers Bureau. Cowan: Janssen: Consultancy, Research Funding; Abbvie: Consultancy, Research Funding; Sanofi Aventis: Consultancy, Research Funding; Bristol Myers Squibb: Research Funding; Secura Bio: Consultancy; Cellectar: Consultancy; Nektar: Research Funding; GSK: Consultancy; Harpoon: Research Funding. Bensinger: BMS, Janssen, Poseida, Regeneron, Trillium: Research Funding; Amgen, BMS, Janssen, Sanofi: Speakers Bureau. Hillengass: Oncotracker: Membership on an entity's Board of Directors or advisory committees; Curio Science: Speakers Bureau; Oncopeptides: Membership on an entity's Board of Directors or advisory committees; Beijing Medical Award Foundation: Speakers Bureau; Adaptive: Membership on an entity's Board of Directors or advisory committees; GlaxoSmithKline: Membership on an entity's Board of Directors or advisory committees; Sanofi: Membership on an entity's Board of Directors or advisory committees; Skyline: Membership on an entity's Board of Directors or advisory committees; Axxess Network: Membership on an entity's Board of Directors or advisory committees; Bristol Myers Squibb: Membership on an entity's Board of Directors or advisory committees; Beijing Life Oasis Public Service Center: Speakers Bureau. Leleu: Amgen: Honoraria; Bristol-Myers Squibb: Honoraria; Carsgen Therapeutics Ltd: Honoraria; Celgene: Honoraria; Gilead Sciences: Honoraria; AbbVie: Honoraria; Janssen-Cilag: Honoraria; Karyopharm Therapeutics: Honoraria; Merck: Honoraria; Mundipharma: Honoraria; Novartis: Honoraria; Oncopeptides: Honoraria; Pierre Fabre: Honoraria; Roche: Honoraria; Sanofi: Honoraria; Takeda: Honoraria, Other: Non-financial support. Lipe: Seagen Inc.: Research Funding; BMS: Consultancy, Research Funding; Janssen: Consultancy, Research Funding; sanofi: Consultancy; GlaxoSmithKline: Consultancy; amgen: Research Funding; Cellectar: Research Funding; Karyopharm: Research Funding; Harpoon: Research Funding. Nath: Harpoon Therapeutics: Consultancy, Current equity holder in publicly-traded company. Sun: Harpoon Therapeutics: Consultancy, Current equity holder in publicly-traded company, Ended employment in the past 24 months.

e20020 Background: Exportin 1 (XPO1) mediates the nuclear export and functional inactivation of tumor suppressor proteins, is required for MM growth, is associated with poor prognosis in MM and mediates resistance to standard MM therapies. Selinexor (SEL) is a first-in-class, oral selective inhibitor of nuclear export (SINE) compound approved in combination with dexamethasone (dex) ± bortezomib for patients (pts) with previously treated MM. Once MM becomes refractory to αCD38 mAb, pts have limited effective treatment options and poor prognosis. Overall response rate (ORR) to the first regimen after refractoriness to an αCD38 mAb is 31%, median progression-free survival (mPFS) is 3.4 months (m), and median overall survival (mOS) is 8.6 m. The doublet SEL-dex (Xd) has shown ORR ̃26% in triple-class (IMID, PI, αCD38 mAb) refractory MM; SEL-based triplets could be more effective in this population. Methods: STOMP (Selinexor and Backbone Treatments of Multiple Myeloma Patients) is a multi-arm, open-label, Phase 1b/2 study evaluating SEL in various triplet combinations. Here, we retrospectively analyzed the efficacy and safety of SEL-containing triplets in pts previously treated with αCD38 mAbs. Pts received SEL-dex (Xd) plus pomalidomide (XPd, n = 19), bortezomib (XVd, n = 4), lenalidomide (XRd, n = 4), daratumumab (XDd, n = 2) or carfilzomib (XKd, n = 18). ORR, mOS, mPFS and adverse events (AEs) were analyzed. Results: Among the 47 pts, median age 64 yrs, female 53%, median time from diagnosis 5.1 yrs, median number of prior regimens 5 (range, 2–11). Prior daratumumab (96%), isatuximab (4%); 96% had MM refractory to aCD38 mAb, 81% had triple-class refractory MM, 74% and 47% were quad- and penta-exposed, 43% and 15% had quad- and penta-refractory MM. αCD38 mAb was included in the immediate prior regimen of 57% of pts and median duration from end of most recent aCD38 mAb therapy to first dose of study treatment was 6.9 weeks (range, 2.6-114.9). ORR was 51% among the 45 evaluable pts, 59% in the XPd arm (n = 17; 2 pts were not efficacy evaluable) and 67% in the XKd arm. ORR was 47% (9/19) among pts with quad-refractory MM and evaluable efficacy. Among all evaluable pts mPFS was 8.8 m (95% CI: 4.9, NE) and mOS was 20.4 m (95% CI: 9.6, NE). Among the 25 pts with αCD38 mAb in their immediate prior regimen, efficacy was similar to that regimen: ORR 52% vs. 45%, mPFS 8.8 vs. 9.3 m. The most common treatment emergent AEs were nausea (72%), anemia (64%), thrombocytopenia (60%), fatigue (57%), which were managed with standard supportive care and dose modifications. Conclusions: SEL-containing triplets in pts with MM previously treated with αCD38 mAbs, most of whom had triple-class refractory MM, exhibit tolerability and comparable effectiveness to their most recent αCD38 mAb-containing regimens. Compared to historical control, mOS was much higher among these patients. Further investigation is warranted. Clinical trial information: NCT02343042.

Background Proteasome inhibitors (PIs), including carfilzomib, potentiate the activity of selinexor, a novel, first-in-class, oral selective inhibitor of nuclear export (SINE) compound, in preclinical models of multiple myeloma (MM). Methods The safety, efficacy, maximum-tolerated dose (MTD) and recommended phase 2 dose (RP2D) of selinexor (80 or 100 mg) + carfilzomib (56 or 70 mg/m 2 ) + dexamethasone (40 mg) (XKd) once weekly (QW) was evaluated in patients with relapsed refractory MM (RRMM) not refractory to carfilzomib. Results Thirty-two patients, median prior therapies 4 (range, 1–8), were enrolled. MM was triple-class refractory in 38% of patients and 53% of patients had high-risk cytogenetics del(17p), t(4;14), t(14;16) and/or gain 1q. Common treatment-related adverse events (all/Grade 3) were thrombocytopenia 72%/47% (G3 and G4), nausea 72%/6%, anaemia 53%/19% and fatigue 53%/9%, all expected and manageable with supportive care and dose modifications. MTD and RP2D were identified as selinexor 80 mg, carfilzomib 56 mg/m 2 , and dexamethasone 40 mg, all QW. The overall response rate was 78% including 14 (44%) ≥ very good partial responses. Median progression-free survival was 15 months. Conclusions Weekly XKd is highly effective and well-tolerated. These data support further investigation of XKd in patients with MM.

Part B of this phase 1b study (ClinicalTrials.gov number, NCT02283775) evaluated safety and efficacy of a fixed-volume infusion of isatuximab, an anti-CD38 monoclonal antibody, in combination with pomalidomide and dexamethasone (Pd) in relapsed/refractory multiple myeloma patients. Isatuximab (10 mg/kg weekly for 4 weeks, then every other week) was administered as a fixed-volume infusion of 250 mL (mL/h infusion rate) with standard doses of Pd on 28-day cycles. Patients ( N = 47) had a median of three prior treatment lines (range, 1–8). Median duration of exposure was 36.9 weeks and median duration of first, second, and 3+ infusions were 3.7, 1.8, and 1.2 h, respectively. The most common non-hematologic treatment-emergent adverse events were fatigue (63.8%), infusion reactions (IRs), cough, and upper respiratory tract infection (40.4% each). IRs were all grade 2 and occurred only during the first infusion. The overall response rate was 53.2% in all patients (55.5% in response-evaluable population, 60.0% in daratumumab-naïve patients). Efficacy and safety findings were consistent with data from the isatuximab plus Pd infusion schedule in Part A of this study and also from the phase 3 ICARIA-MM study, and these new data confirm the safety, efficacy, and feasibility of fixed-volume infusion of isatuximab.

Context: To reduce infusion duration, fixed-volume infusion of isatuximab (Isa), a CD38 monoclonal antibody, was confirmed to be feasible and safe in the primary analysis. Objective: Evaluate efficacy and safety of a fixed-volume infusion of Isa plus pomalidomide and dexamethasone (Pd) in relapsed/refractory multiple myeloma (RRMM). Design: This two-part, Phase 1b study ( NCT02283775 ) enrolled RRMM patients who had received ≥2 prior lines of therapy, including lenalidomide and a proteasome inhibitor, and who demonstrated disease progression. Part A was an Isa dose-escalation study. In Part B, Isa (10 mg/kg) was administered as a fixed infusion volume of 250 mL (mL/h infusion rate) with standard doses of Pd. The primary endpoint for Part B was incidence of Grade (Gr) ≥3 infusion reactions (IRs) during the first 6 Isa infusions. Secondary endpoints included duration of infusion, safety, efficacy, and immunogenicity. Results: Of 47 patients enrolled in Part B, 22 (47%) remained on treatment at data cut-off. Patients were heavily pretreated, with a median of 3 prior treatment lines (range, 1–8). Median duration of exposure was 36.9 weeks (range, 1–77). IRs were reported in 19/47 (40%) patients, all Gr 2, and occurred only during first infusion. Median duration of the first, second and ≥3 infusions was 3.7, 1.8, and 1.2 hours, respectively. All patients experienced ≥1 treatment-emergent adverse event (TEAE). The most common non-hematologic TEAEs were fatigue (64%), IRs, cough, and upper respiratory tract infection (40% each); 6 patients (13%) died within 30 days of final study treatment. The overall response rate was 53% in all patients. Median time to first response was 0.95 months (range, 0.9–3.4). At a median duration of 9.9 months follow-up (range, 0–17.3), median duration of response, progression-free survival, and overall survival were not reached. Conclusions: Efficacy and safety findings were consistent with Part A of this study and the pivotal Phase 3 ICARIA study. Measurements of response were robust. There were no Gr ≥3 IRs, and all occurred during first infusion. These results confirm the safety, efficacy, and feasibility of Isa administered by a fixed infusion volume. Funding for this study was provided by Sanofi.

To improve disease control without increasing the toxicity of a reduced-intensity allogeneic hematopoietic cell transplantation (HCT) in multiple myeloma (MM), a phase I trial was performed using an antibody-radionuclide conjugate targeting CD45 (90Y-DOTA-BC8) as conditioning. 90Y-DOTA-BC8 was combined with fludarabine and low-dose TBI followed by allogeneic HCT in patients with MM and ≥1 adverse risk characteristic at diagnosis, relapse after autologous transplant, or plasma cell leukemia (PCL). The primary objective was to estimate the maximum tolerated radiation absorbed dose. Fourteen patients were treated (one with PCL, nine failed prior autologous HCT, and nine with ≥1 adverse cytogenetics). Absorbed doses up to 32 Gy to liver were delivered. No dose-limiting toxicities occurred. Non-hematologic toxicities were manageable and included primarily gastrointestinal (43%) and metabolic/electrolyte disturbances (36%). Treatment-related mortality at 100 days was 0%. At a median follow-up of 5 years, the overall survival was 71% (median not reached) and the progression-free survival was 41% (median 40.9 months). The incorporation of CD45-targeted radioimmunotherapy (RIT) into a reduced-intensity allogeneic HCT is well-tolerated and may induce long-term remissions among patients with poor-risk MM, supporting further development of RIT-augmented conditioning regimens for HCT.

Background : Selinexor (SEL) is a novel, first-in-class oral selective inhibitor of nuclear export (SINE) which blocks XPO1, forcing the nuclear retention and activation of tumor suppressor proteins, ultimately causing cell death in cancer cells. SEL 80 mg and dexamethasone (dex) 20 mg, both twice weekly (BIW), received accelerated approval from the FDA for patients (pts) with relapsed refractory multiple myeloma (RRMM). SEL continues to be evaluated in earlier lines of therapy with once weekly administration and in combination regimens. The SVd regimen with once weekly (QW) oral SEL (100 mg), dexamethasone (dex) and QW bortezomib (BOR) had significantly increased progression free survival (PFS) and overall response rate (ORR) with significantly reduced peripheral neuropathy as compared to standard BIW BOR/dex (Vd) in the phase III BOSTON study. The combination of lenalidomide (LEN) and dex (Rd) is an approved regimen in RRMM and newly diagnosed MM (NDMM) with an ORR of 70-76% in RRMM but a low complete response rate. SEL showed synergistic antitumor activity with LEN in a MM xenograft model. Therefore, we hypothesized that the all oral combination of weekly SEL with standard Rd (i.e., SRd) could improve the efficacy compared with Rd in pts with RRMM and NDMM with acceptable toxicity profile. Methods: STOMP is a phase 1b/2 multicenter, open-label, clinical trial with the goals of determining the maximum tolerated dose, the recommended phase 2 dose (RP2D), efficacy and safety of SRd in pts with RRMM or NDMM. For RRMM, SEL was dose escalated in two regimens QW (starting at SEL 80 mg) or BIW (starting at 60 mg), LEN 25 mg PO daily and DEX 20 mg BIW or 40 mg QW. Results: As of June 1, 2020, 24 pts (13 male, 11 female) with RRMM were enrolled. The median age was 67 years (range, 49-84) and the median number of prior lines of therapy was 1.5 (range, 1 - 8). In the 60 mg BIW dosing, 4 pts experienced dose limiting toxicities (DLTs) out of 5 pts dosed (2 thrombocytopenia, 1 anorexia, 1 >25% missed dose due to unrelated QT interval prolongation). In the 80 mg QW dosing, 2 pts experienced DLTs out of 6 pts (both grade 4 thrombocytopenia). In the 60 mg QW dosing, no DLTs were observed. Based on these data, the RP2D of SRd was determined to be: SEL 60 mg QW, LEN 25 mg QD and DEX 40 mg QW. Common treatment related adverse events (TRAEs) (All Grades, ≥3) were thrombocytopenia (71%, 63%), neutropenia (63%, 63%), nausea (58%, 4%), fatigue (54%, 17%), decreased appetite (50%, 8%), and weight loss (42%, 8%). Amongst the 20 pts with RRMM where efficacy was evaluable, previously treated/documented refractory rates were: bortezomib (100%, 45%), LEN (40%, 25%), daratumumab (20%, 20%), and pomalidomide (20%, 20%). Amongst the LEN naïve pts (n=12), the ORR was 92% including 1 stringent complete response [sCR], 4 very good partial responses [VGPR] and 6 partial responses [PR, 2 unconfirmed]). PFS in LEN naïve pts has not been reached with a median follow-up period of 7.8 months. In the pts with prior LEN treatment (n=8), the ORR was 13%. Based on the high levels of activity of SRd in LEN naïve pts, 8 pts (4 males and 4 females) with NDMM were enrolled at the RP2D. The median age was 74 (range: 51-86) years. No DLTs were observed in 5 DLT evaluable pts. Common TRAEs (All Grades, ≥3) were thrombocytopenia (63%, 38%), neutropenia (75%, 75%), fatigue (63%, 50%), nausea (50%, 0%), weight loss (63%, 0%), and decreased appetite (13%, 13%). All 7 efficacy evaluable pts achieved a response, an ORR of 100%, including 1 CR, 4 VGPR, and 2 PR. With a median follow-up of 10.2 months, median PFS has not been reached. Out of these 7 pts, three pts withdrew consent to transit to successful autologous stem cell collection and transplantation. Conclusions: The all oral combination of SRd with once weekly SEL 60 mg, LEN 25 mg QD and DEX 40 mg QW was established as the RP2D for pts with RRMM or NDMM. The safety profile was similar in both settings. All TRAEs were manageable with adequate supportive care and/or dose modification. The all oral combination of SRd has demonstrated ORR of 92% in pts with LEN naïve RRMM and ORR of 100% in pts with NDMM, warranting further investigation of SRd with or without additional anti-MM agents for the treatment of pts with NDMM. Disclosures White: Sanofi: Honoraria; Janssen: Honoraria; Celgene: Honoraria; Amgen: Honoraria; Takeda: Honoraria; Karyopharm: Honoraria; Antengene: Honoraria; GSK: Honoraria. LeBlanc:Celgene: Research Funding; Celgene Canada; Janssen Inc.; Amgen Canada; Takeda Canada: Membership on an entity's Board of Directors or advisory committees. Baljevic:NCCN Hematologic Malignancies Congress: Honoraria; MediCom Myeloma CME: Honoraria; Amgen: Research Funding; Exelixis: Research Funding; Celgene Corporation / BMS: Consultancy, Membership on an entity's Board of Directors or advisory committees; Cardinal Health: Consultancy, Membership on an entity's Board of Directors or advisory committees; Putnam Associates: Consultancy, Membership on an entity's Board of Directors or advisory committees; Gerson Lehrman Group: Consultancy, Membership on an entity's Board of Directors or advisory committees; AlphaSights: Consultancy, Membership on an entity's Board of Directors or advisory committees; Coleman: Consultancy, Membership on an entity's Board of Directors or advisory committees; Karyopharm Therapeutics Inc.: Honoraria. Bahlis:Karyopharm Therapeutics: Consultancy, Honoraria; GSK: Consultancy, Honoraria; Genentech: Consultancy, Honoraria; AbbVie: Consultancy, Honoraria; BMS/Celgene and Janssen: Consultancy, Honoraria, Other: Travel, Accomodations, Research Funding; Sanofi: Consultancy, Honoraria; Takeda: Consultancy, Honoraria; Amgen: Consultancy, Honoraria. Lentzsch:Celularity: Consultancy; Sorrento: Consultancy; Janssen: Consultancy; Caelum Biosciences: Current equity holder in private company, Membership on an entity's Board of Directors or advisory committees; Mesoblast: Divested equity in a private or publicly-traded company in the past 24 months; Sanofi: Research Funding; Magenta: Current equity holder in private company; Karyopharm: Research Funding. Venner:Celgene, Amgen: Research Funding; Janssen, BMS/Celgene, Sanofi, Takeda, Amgen: Honoraria. Chen:Amgen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; AstraZeneca: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Celgene: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; AbbVie: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Janssen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Sanofi: Research Funding. Lipe:Amgen: Membership on an entity's Board of Directors or advisory committees; Celgene: Membership on an entity's Board of Directors or advisory committees; GlaxoSmithKline: Membership on an entity's Board of Directors or advisory committees; Janssen: Membership on an entity's Board of Directors or advisory committees. Tuchman:Roche: Research Funding; Oncopeptides: Consultancy; Janssen: Research Funding; Amgen: Research Funding; Sanofi: Honoraria, Research Funding; Caelum: Honoraria; Karyopharm: Honoraria, Research Funding; Celgene: Honoraria, Research Funding, Speakers Bureau. Sutherland:Janssen: Consultancy, Honoraria; Bristol Myers Squibb: Consultancy, Honoraria; Takeda: Consultancy, Honoraria; Celgene: Consultancy; Amgen: Consultancy. Kotb:Merck: Honoraria, Research Funding; Karyopharm: Current equity holder in publicly-traded company; Takeda: Honoraria; Celgene: Honoraria; Sanofi: Research Funding; Amgen: Honoraria; Janssen: Honoraria. Sebag:Amgen: Honoraria; Janssen: Honoraria, Research Funding; Celgene: Honoraria; Takeda: Honoraria. Callander:Cellectar: Research Funding; University of Wisconsin: Current Employment. Bensinger:BMS: Consultancy, Honoraria, Research Funding, Speakers Bureau; Sanofi: Consultancy, Honoraria, Research Funding, Speakers Bureau; Janssen: Consultancy, Honoraria, Research Funding, Speakers Bureau; Amgen: Consultancy, Honoraria, Research Funding, Speakers Bureau; GSK: Consultancy, Honoraria, Research Funding, Speakers Bureau; Regeneron: Consultancy, Honoraria, Research Funding, Speakers Bureau. Rossi:Amgen: Membership on an entity's Board of Directors or advisory committees; BMS: Membership on an entity's Board of Directors or advisory committees; Janssen: Membership on an entity's Board of Directors or advisory committees. Sheehan:Karyopharm Therapeutics Inc: Current Employment. Van Domelen:Karyopharm Therapeutics Inc: Current Employment, Current equity holder in publicly-traded company. Zhou:Karyopharm Therapeutics Inc.: Current Employment, Current equity holder in publicly-traded company. Kazuharu:Karyopharm Therapeutics Inc.: Current Employment. Shah:Karyopharm Therapeutics Inc: Current Employment, Current equity holder in publicly-traded company. Shacham:Karyopharm: Current Employment, Current equity holder in publicly-traded company, Patents & Royalties: (8999996, 9079865, 9714226, PCT/US12/048319, and I574957) on hydrazide containing nuclear transport modulators and uses, and pending patents PCT/US12/048319, 499/2012, PI20102724, and 2012000928) . Kauffman:Karyopharm Therapeutics Inc: Current Employment, Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees. Schiller:Ariad: Research Funding; Actinium: Research Funding; Jazz Pharmaceuticals: Research Funding; Johnson & Johnson: Current equity holder in publicly-traded company; Kaiser Permanente: Consultancy; Trovagene: Research Funding; Tolero: Research Funding; Sangamo: Research Funding; Samus: Research Funding; Regimmune: Research Funding; Pfizer: Current equity holder in publicly-traded company, Research Funding; Karyopharm: Research Funding; Kite Pharma: Research Funding; Mateon: Research Funding; MedImmune: Research Funding; Onconova: Research Funding; Cyclacel: Research Funding; Daiichi Sankyo: Research Funding; Deciphera: Research Funding; Astellas Pharma: Honoraria, Research Funding; Agios: Consultancy, Research Funding, Speakers Bureau; Amgen: Consultancy, Current equity holder in publicly-traded company, Research Funding, Speakers Bureau; Celator: Research Funding; Abbvie: Research Funding; Constellation: Research Funding; Ono Pharma: Consultancy; Novartis: Consultancy, Research Funding; Stemline: Speakers Bureau; Incyte: Consultancy, Research Funding, Speakers Bureau; AstraZeneca: Consultancy; Gilead: Speakers Bureau; Sanofi: Speakers Bureau; Celgene: Research Funding, Speakers Bureau; Bristol-Myers Squibb: Current equity holder in publicly-traded company, Research Funding; DeltaFly: Research Funding; Forma: Research Funding; Gamida: Research Funding; FujiFilm: Research Funding; Genentech-Roche: Research Funding; Geron: Research Funding.