ALBERT

Description: Background AFM11 is a bispecific, tetravalent T cell-engaging antibody construct binding to CD19 on B cell origin malignant cells such as B-precursor acute lymphoblastic leukemia (B-ALL) and to CD3 on T cells. By engaging CD3-positive T cells, AFM11 elicits T cell-mediated killing of CD19-positive (CD19+) leukemia and lymphoma cells. In vivo anti-tumor activity of AFM11 was investigated in a Raji tumor xenograft model in non-obese diabetic/severe combined immunodeficiency (NOD/scid) mice reconstituted with human peripheral blood mononuclear cells (PBMC). Tumor growth in all AFM11-treated animal groups was significantly reduced. In the highest dose group, all animals achieved complete tumor remission. (Reusch et al., 2015). An ongoing Phase 1 study assesses safety, tolerability, pharmacokinetics (PK), pharmacodynamics (PD) and preliminary efficacy of AFM11 in patients with relapsed/refractory (R/R) CD19+ B-ALL. Methods Patients (pts) with relapsed or refractory CD19+ B-ALL are being enrolled into escalating cohorts of 1-6 pts. The primary objective of the study is to determine the maximum tolerated dose (MTD) of AFM11 administered as a 2-week continuous intravenous (CIV) infusion. AFM11 is administered over the first 2 weeks (wks) of each 4 wk cycle for up to 3 cycles. Pts with rapidly progressing disease receive pre-treatment with 200 mg cyclophosphamide and 10 mg/m2 dexamethasone over 3-5 days before initiating AFM11. A lower starting dose is employed during the first wk of cycle 1 and escalated to a target dose during the second wk of cycle 1 and all subsequent cycles. An accelerated titration design is used until toxicity is observed, followed by a classical 3+3 design. PD activity is assessed by flow cytometry of peripheral blood lymphocytes and serum cytokine measurements. Tumor response is evaluated by local bone marrow and peripheral blood laboratory results between days 15 and 18 of each cycle. Results As of June 29, 2018, fourteen pts (8 female/6 male) have been treated in 5 cohorts. The median age is 41.5 years (range 19-67) and the median number of prior therapies is 5 (range 1-12). AFM11 was well-tolerated with no dose-limiting toxicities (DLTs) observed in the first 5 cohorts. The study switched to 3+3 design in cohort 3 due to the occurrence of grade 2 AFM11-related events in cohort 2. Enrollment into cohort 6 is ongoing and the MTD has not yet been reached. The most frequent (≥2 pts) AFM11-related adverse events were pyrexia (29%), myalgia (14%), and tremor (14%). Most of the events were Common Terminology Criteria for Adverse Events (CTCAE) v4.03 grade 1-2, with one grade 3 and no grade 4 events observed. Transient and reversible neurological events occurred in 3 of 14 (21%) pts: grade 1 paresthesia (n=1), grade 1/grade 2 tremor (n=1 each), grade 2 lethargy (n=1); and grade 3 altered state of consciousness (n=1). The grade 3 event occurred during the third cycle of treatment and was managed with treatment interruption and steroids and resolved within 48 hours. The pt then completed the third cycle at a reduced AFM11 dose without incident. Peripheral B cell reductions were observed in multiple pts in cohorts 4 and 5 and notable cytokine release was detected in two pts. Two pts achieved complete remission with complete hematological recovery (CR): one pt in cohort 4 achieved CR after the first cycle and progressed 2 wks later; one pt in cohort 5 achieved CR after the first cycle which was sustained after the second and third cycles and was assessed as minimal residual disease (MRD) negative after cycle 3. As a result, this pt became eligible to receive stem cell transplantation upon study completion. Both CR pts had peripheral B-cell aplasia after the first few days of treatment. Updated data will be presented. Conclusions The CD19/CD3-targeting tetravalent bispecific T cell engager AFM11 was well-tolerated in pts with R/R B-ALL across the first 5 cohorts of an ongoing Phase 1 study, and the MTD has not been reached. Pyrexia was the most frequently observed related adverse event. Transient neurological events were observed and were consistent with those associated with other CD19-targeted therapies. Peripheral B cell reductions and complete remissions observed in pts treated in the higher dose cohorts suggest that AFM11 is active in pts with R/R B-ALL and that the study is nearing determination of the therapeutic dose and schedule. Disclosures Salogub: Affimed: Research Funding. Mayer:Novartis: Research Funding; Roche: Research Funding; Eisai: Research Funding; Johnson & Johnson: Research Funding; Affimed: Research Funding. Folber:Affimed: Research Funding. Grosicki:Affimed: Research Funding. Skotnicki:Affimed: Research Funding. Prochwicz:Affimed: Research Funding. Myasnikov:Affimed: Research Funding. Gural:Affimed: Research Funding. Schoenborn-Kellenberger:Affimed: Consultancy. Brindley:Affimed: Consultancy. Knackmuss:Affimed: Employment. Schwarz:Affimed: Employment. Schmich:Affimed: Employment. Choe-Juliak:Affimed: Employment. Strassz:Affimed: Employment. Alland:Affimed: Employment. Doubek:AbbVie: Consultancy, Research Funding; Gilead: Consultancy, Honoraria, Research Funding; Janssen: Consultancy, Honoraria; Roche: Consultancy, Honoraria; Affimed: Research Funding; Novartis: Consultancy.

Description: Introduction - Inhibition of Exportin 1 (XPO1) is a novel treatment approach for multiple myeloma (MM). XPO1 mediates the nuclear export of cell-cycle regulators and tumor suppressor proteins leading to their functional inactivation. In addition, XPO1 promotes the export and translation of the mRNA of key oncoproteins (e.g. c-MYC, BCL-2, Cyclin D). XPO1 overexpression occurs in solid and hematological malignancies, including MM and is essential for MM cell survival. Selinexor, the first oral SINE compound, has shown promising anti-MM activity in phase 1 studies but has been associated with gastrointestinal and constitutional toxicities including nausea, anorexia and fatigue. KPT-8602 is a second generation oral SINE compound with similar in vitro potency to selinexor, however, has substantially reduced brain penetration compared with selinexor, and demonstrated markedly improved tolerability with minimal anorexia and weight loss in preclinical toxicology studies. In murine models of MM, KPT-8602 can be dosed daily (QDx5) with minimal anorexia and weight loss. We have therefore initiated a phase 1/2 first-in-human clinical trial. Methods - This phase 1/2 clinical trial was designed to evaluate KPT-8602 as a single agent and in combination with low dose dexamethasone (dex) in patients (pts) with relapsed / refractory MM (RRMM). KPT-8602 is dosed orally (QDx5) for a 28-day cycle with a starting dose of 5 mg. Low dose dex (20 mg, twice weekly) is allowed after cycle 1 if at least a minimal response (MR) is not observed. The primary objective is to evaluate the safety and tolerability including dose-limiting toxicity (DLT), determine the maximum tolerated dose (MTD), the recommended Phase 2 dose (RP2D), and evidence for anti-MM activity for KPT-8602 single agent and in combination with dex. The pharmacokinetic (PK) and pharmacodynamic (PDn; XPO1 mRNA) profile of KPT-8602 will also be determined. PDn predictive biomarker analysis and ex vivo drug response assays are underway using tumor cells from bone marrow aspirates before treatment, during and at relapse. These analyses include cell death pathway assays by flow and nuclear/cytoplasmic localization of XPO1, NF-ƙB, IƙBα, IKKα, NRIF and p53 by imaging flow and IHC. Results - As of 01-Aug-2016, 6 pts 2 M/4 F, (median of 6 prior treatment regimens, median age of 71) with RRMM have been enrolled. Common related grade 1/2 adverse events (AEs) include thrombocytopenia (3 pts), nausea (2 pts) and diarrhea (2 pts). Grade 3 AEs include neutropenia (1 pt) and dehydration (1 pt). No grade 4 or 5 AEs have been reported. No DLTs have been observed and the MTD has not been reached. 5 pts were evaluable for responses (1 pt pending evaluation): 1 partial response, 1 minimal response, and 3 stable disease; no pts have progressed on therapy with the longest on for 〉5 months. The PK properties following oral administration showed that 5 mg of KPT-8602 was rapidly absorbed (mean tmax= 1 hr, mean Cmax= 30.6 ng/mL). The mean AUCinf was calculated to be 141 ng•hr/mL. After tmax, KPT-8602 declined at an estimated mean t½ of 4 hr. At the same dose level, XPO1 mRNA expression was the highest (~2.5 fold) at 8 hr post dose. Conclusions - Oral KPT-8602 is well tolerated in heavily pretreated pts with RRMM. Gastrointestinal and constitutional toxicities observed with twice weekly selinexor have not been observed with 5x/week KPT-8602, including in pts on study for 〉4 months. PK was predictable and in line with selinexor. These early results show encouraging disease control with pts remaining on therapy. Enrollment is on-going. Disclosures Rossi: Takeda: Speakers Bureau; Janssen: Speakers Bureau; Onyx: Research Funding, Speakers Bureau; Celgene: Consultancy, Speakers Bureau. Baz:Takeda/Millennium: Research Funding; Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Karyopharm: Research Funding; Signal Genetics: Research Funding; Bristol-Myers Squibb: Research Funding; Merck: Research Funding; Novartis: Research Funding. Hofmeister:Karyopharm Therapeutics: Research Funding; Arno Therapeutics, Inc.: Research Funding; Signal Genetics, Inc.: Membership on an entity's Board of Directors or advisory committees; Janssen: Pharmaceutical Companies of Johnson & Johnson: Research Funding; Incyte, Corp: Membership on an entity's Board of Directors or advisory committees; Celgene: Research Funding; Takeda Pharmaceutical Company: Research Funding; Teva: Membership on an entity's Board of Directors or advisory committees. Shustik:Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees; Millenium: Honoraria, Membership on an entity's Board of Directors or advisory committees; Takeda: Honoraria, Membership on an entity's Board of Directors or advisory committees; Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees; Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees. Richter:Amgen: Consultancy, Speakers Bureau; Takeda: Consultancy, Speakers Bureau; Celgene: Consultancy, Speakers Bureau; Jannsen: Speakers Bureau. Chen:Janssen: Honoraria, Research Funding; Takeda: Research Funding; Celgene: Honoraria, Research Funding. Vogl:Takeda: Consultancy, Research Funding; Celgene: Consultancy; GSK: Research Funding; Calithera: Research Funding; Teva: Consultancy; Karyopharm: Consultancy; Acetylon: Research Funding; Constellation: Research Funding. Shacham:Karyopharm Therapeutics: Employment, Equity Ownership, Membership on an entity's Board of Directors or advisory committees. Baloglu:Karyopharm Therapeutics: Employment, Equity Ownership. Senapedis:Karyopharm Therapeutics: Employment, Equity Ownership. Ellis:Karyopharm Therapeutics: Employment, Equity Ownership. Friedlander:Karyopharm Therapeutics: Employment. Choe-Juliak:Karyopharm Therapeutics: Employment. Sullivan:Karyopharm Therapeutics: Research Funding. Kauffman:Karyopharm Therapeutics Inc: Employment, Equity Ownership, Membership on an entity's Board of Directors or advisory committees.

Description: Background AFM13 is a bispecific, tetravalent NK cell-engaging antibody construct binding to CD30 on CD30+ tumor cells and CD16A on NK cells. By engaging CD16A-positive NK cells, AFM13 leads to NK cell-mediated killing of CD30-positive lymphoma cells (Reusch et al., 2014) making it an attractive agent to target classical Hodgkin lymphoma (HL). Pembrolizumab is a PD-1 blocking antibody which has shown high single-agent response rates in patients (pts) with relapsed/refractory HL (RRHL; Armand et al., 2016, Chen et al., 2017). AFM13 has shown clinical activity in RRHL as a single agent in a preceding Phase 1 study (Rothe et al., 2015). Preclinical in vivo data of the combination of AFM13 with PD-1 blockade showed synergistic activity and the potential for induction of cross-talk between innate and adaptive immunity (Zhao et al., 2016). We hypothesize that the combination of the two agents could improve outcomes in pts with RRHL. Methods This Phase 1b study is evaluating the safety and tolerability of the combination of AFM13 with pembrolizumab (Keytruda) as salvage therapy after failure of standard therapies including brentuximab vedotin (BV) in HL (NCT02665650). Pts receive escalating doses of AFM13 in combination with pembrolizumab at a dose of 200 mg flat administered every 3 weeks following a classical 3+3 design, followed by enrollment into an extension cohort at the maximum tolerated dose (MTD)/maximum administered dose (MAD). Response assessment is performed every 12 weeks by PET/CT according to the Lugano Classification (Cheson et al., 2014). The main objectives of the study is to ascertain the MTD/MAD along with the preliminary efficacy of the combination. Results As of June 29, 2018, 30 pts have been enrolled into the study. The median age is 34 years (range, 18-73), with a median of 4 (range 3-7) prior lines of therapy. All pts had relapsed or refractory disease (43% relapsed, 57% refractory) and had failed standard treatments including BV and 43% of pts (13/30) had BV as their latest therapy. Thirty seven percent (11/30) had undergone prior autologous stem cell transplantation. All 30 pts have completed the 6-week dose-limiting toxicity (DLT) observation period. Twelve pts were enrolled into the dose escalation cohorts (Cohorts 1 (n=3), 2 (n=3), and 3 (n=6)) and 18 into the Extension Cohort, with a total of 24 patients treated at the MAD (dose level 3). One DLT was observed in Cohort 3 (missing ≥25% of AFM13 during the DLT period) and another observed in the Extension Cohort (G4 infusion-related reaction; IRR). The most common related adverse events (AEs) were IRRs (80%), rash (30%), pyrexia (23%), nausea (23%), diarrhea (20%), fatigue (17%), headache (17%), increased aspartate aminotransferase (13%), and increased alanine aminotransferase (10%). Treatment related G3/4 AEs included IRRs (13%), elevated AST (3%), gastritis (3%), hypotension (3%), nausea (3%), neutropenia (3%), and vomiting (3%). The majority of IRRs were manageable with standard of care measures and did not lead to treatment discontinuations. Included in the efficacy analysis were the best response from 29 evaluable pts who had at least one post-baseline disease assessment as of the data cutoff on June 29, 2018. The overall response rate (ORR) and complete response (CR) rate for evaluable pts treated at the dose and schedule chosen for expansion (n=23; Cohort 3 and Extension Cohort) were 87% and 35% by the investigator-confirmed assessment, respectively. Independent assessment resulted in an ORR of 87% and CR rate of 39% for these pts. Updated data for all 30 patients will be presented at the meeting. Conclusions The combination of AFM13 and pembrolizumab is a well-tolerated salvage therapy in pts with RRHL. IRRs were the most frequently observed adverse events; however, most of these events were of mild or moderate severity and manageable. Both the ORR and CR rate compare favorably to monotherapy pembrolizumab in a similar RRHL population (Chen et al., 2017). The combination of AFM13 and pembrolizumab could be a potential new therapeutic option for HL patients. Disclosures Bartlett: Immune Design: Research Funding; Affimed: Research Funding; Bristol-Meyers Squibb: Research Funding; Merck & Co: Research Funding; Pharmacyclics: Research Funding; Celgene: Research Funding; Pharmacyclics: Research Funding; Genentech: Research Funding; Forty Seven: Research Funding; Novartis: Research Funding; Novartis: Research Funding; Millennium: Research Funding; ImaginAB: Research Funding; Pfizer: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Gilead: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Janssen: Research Funding; KITE: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Seattle Genetics: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Astra Zeneca: Research Funding; Acerta: Membership on an entity's Board of Directors or advisory committees. Chen:Affimed: Research Funding; Bristol-Myers Squibb: Consultancy, Research Funding; Genentech Inc.: Consultancy; Seattle Genetics: Consultancy, Honoraria, Research Funding, Speakers Bureau; Merck & Co., Inc.: Consultancy, Research Funding, Speakers Bureau; Millennium Pharmaceuticals: Consultancy, Research Funding; Pharmacyclics: Consultancy, Research Funding. Domingo-Domenech:Affimed: Research Funding. Forero-Torres:Affimed: Research Funding. Garcia-Sanz:Affimed: Research Funding. Devata:Affimed: Research Funding. Rodriguez Izquierdo:Affimed: Research Funding. Lossos:Affimed: Research Funding. Reeder:Affimed: Research Funding. Sher:Affimed: Research Funding. Choe-Juliak:Affimed: Employment. Prier:Affimed: Research Funding. Schwarz:Affimed: Employment. Strassz:Affimed: Employment. Alland:Affimed: Employment. Ansell:Bristol-Myers Squibb: Research Funding; Celldex: Research Funding; LAM Therapeutics: Research Funding; Trillium: Research Funding; Pfizer: Research Funding; Regeneron: Research Funding; Seattle Genetics: Research Funding; Merck & Co: Research Funding; Affimed: Research Funding; Takeda: Research Funding.

Description: Introduction - The nuclear export protein exportin 1, (XPO1) is overexpressed in a wide variety of cancers including multiple myeloma (MM). Selinexor is a first-in-class Selective Inhibitor of Nuclear Export (SINE) compound that binds and inactivates XPO1. Selinexor forces nuclear retention and reactivation of tumor suppressor proteins (TSPs; NF-kB, p53 and FOXO) and reduction of many proto-oncogenes, including MDM2, MYC and Cyclin D. In murine MM models, the combination of selinexor with IMIDs shows synergistic anti-MM activity with good tolerability. Methods - This phase 1b/2 dose escalation study (NCT02343042) using the standard 3+3 design, is designed to determine the tolerability, maximum tolerated dose (MTD), recommended phase 2 dose (RP2D) and preliminary efficacy of selinexor in combination with pomalidomide and dexamethasone (SdP). Patients (pts) with relapsed/refractory MM who received ≥ 2 prior therapies including lenalidomide and a proteasome inhibitor (PI) were enrolled. Selinexor is dose escalated once-weekly (QW, starting at 80 mg) or twice-weekly (BIW, starting at 60 mg), pomalidomide 4 mg PO daily, days 1 -21 and dexamethasone (dex) 40 mg PO weekly in a 28 day cycle. Results - As of 25-Jul-2016, 11 pts (7 male / 4 female) have been enrolled. The median age is 58 years (range, 43 - 76), with a median of 5 (range, 2 - 9) prior treatment regimens. Eight pts had MM refractory to lenalidomide and 7 pts to bortezomib; including 5 pts with MM refractory to both. For the once-weekly selinexor cohort, the 80 mg dose level has been cleared and the 100 mg dose level is on going. For the twice-weekly cohort, the 60 mg dose level has been cleared and 80 mg dose level is on going. Common related grade 1/2 adverse events (AEs) include: nausea 7pts (64%), altered taste 5pts (45%), anorexia 3pts (27%), and diarrhea 3pts (27%). Grade 3/4 AEs include: neutropenia 8pts (73%), thrombocytopenia 4pts (36%), and leukopenia 3pts (27%). There was no febrile neutropenia or bleeding reported to date. No dose limiting toxicities have been observed and MTD has not been reached. Ten pts were evaluable for response including, 1 complete response (CR), 5 partial responses (PR), 3 minor responses (MR), and 1 stable disease (SD). The overall response rate (ORR) is 60% with a clinical benefit rate of 90% (ORR + MR). Responses are rapid in onset, with at least MR achieved by cycle 2 day 1. In lenalidomide and bortezomib refractory patients the ORR was 50%. One pt was deemed not evaluable due to non-compliance with study procedures. Eight pts are still on study, (range 3 months. Conclusions - The all oral combination of selinexor, pomalidomide and low dose dex (SdP) has significant clinical activity (ORR 60%) in pts with heavily pretreated MM. Responses are rapid in onset even with the lower dose cohorts tested thus far, CR can be achieved. No additive toxicities over monotherapy of either pomalidomide or selinexor have been observed. This novel treatment regimen therefore holds promise in addressing the urgent need to induce meaningful and durable responses in patients with IMiD and PI relapsed/refractory MM. Disclosures Chen: Janssen: Honoraria, Research Funding; Celgene: Honoraria, Research Funding; Takeda: Research Funding. Sebag:Celgene: Honoraria; Janssen: Honoraria; Novartis: Honoraria. Sutherland:Janssen: Consultancy, Honoraria; Celgene: Consultancy, Honoraria; Amgen: Consultancy, Honoraria. White:Celgene: Consultancy, Honoraria; Janssen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees. Venner:Takeda: Honoraria; Celgene: Honoraria, Research Funding; J+J: Research Funding; Janssen: Honoraria; Amgen: Honoraria. Kouroukis:Karyopharm: Research Funding; Amgen: Research Funding; Janssen: Research Funding. McCurdy:Celgene: Honoraria. Lalancette:BMS: Honoraria; Celgene: Honoraria. Bensinger:Sanofi: Consultancy, Research Funding; Amgen: Consultancy, Honoraria, Research Funding; Celgene: Consultancy, Honoraria, Research Funding; Bristol Myers Squibb: Consultancy, Research Funding; Acetylon: Research Funding; Bayer: Research Funding; Takeda: Honoraria, Research Funding. Lentzsch:Celgene: Consultancy, Honoraria; BMS: Consultancy. Kauffman:Karyopharm Therapeutics Inc: Employment, Equity Ownership, Membership on an entity's Board of Directors or advisory committees. Shacham:Karyopharm Therapeutics: Employment, Equity Ownership, Membership on an entity's Board of Directors or advisory committees. Jeha:Karyopharm: Employment. Picklesimer:Karyopharm: Employment. Saint-Martin:Karyopharm: Employment. Choe-Juliak:Karyopharm Therapeutics: Employment. Bahlis:BMS: Honoraria; Janssen: Consultancy, Honoraria, Other: Travel Expenses, Research Funding, Speakers Bureau; Celgene: Consultancy, Honoraria, Other: Travel Expenses, Research Funding, Speakers Bureau; Onyx: Consultancy, Honoraria; Amgen: Consultancy, Honoraria.

Description: In relapsed/refractory Hodgkin lymphoma (R/R HL), immunotherapies such as the PD-1 inhibitor pembrolizumab have demonstrated efficacy as monotherapy and are playing an increasingly prominent role in treatment. The CD30/CD16A bispecific antibody AFM13 is an innate immune cell engager, a first-in-class, tetravalent antibody, designed to create a bridge between CD30 on HL cells and the CD16A receptor on NK cells and macrophages, to induce tumor cell killing. Early studies of AFM13 have demonstrated signs of efficacy as monotherapy for patients with R/R HL and the combination of AFM13 with pembrolizumab represents a rational new treatment modality. Here, we describe a Phase 1b, dose-escalation study to assess the safety and preliminary efficacy of AFM13 in combination with pembrolizumab in patients with R/R HL. The primary objective was estimating the MTD; the secondary objectives were to assess safety, tolerability, anti-tumor efficacy, pharmacokinetics, and pharmacodynamics. In this heavily pre-treated patient population, the combination of AFM13 and pembrolizumab was generally well tolerated, with similar safety profiles compared to the known profiles of each agent alone. AFM13 plus pembrolizumab demonstrated objective response rates of 88% at the highest treatment dose, with an 83% ORR for the overall population. Pharmacokinetic assessment of AFM13 in the combination treatment revealed a half-life of up to 20.6 hours. This proof-of-concept study holds promise as a novel immunotherapy combination worthy of further investigation. This Phase 1b study was registered at www.clinicaltrials.gov as NCT02665650.

Description: Introduction - With over 12,000 deaths from MM anticipated in 2016, nearly all patients (pts) with multiple myeloma (MM) will become "quad refractory" to IMIDs (lenalidomide and pomalidomide) and proteasome inhibitors (bortezomib and carfilzomib), and eventually "penta refractory" to anti-CD38 Abs (daratumumab and isatuximab), defining high unmet need populations. Selinexor, an oral selective XPO1 inhibitor, induces nuclear accumulation and activation of tumor suppressor proteins, inhibition of NF-kB, and inhibition of translation of several oncoprotein mRNAs such as c-myc and cyclin D. Selinexor showed potent induction of apoptosis of MM cells independent of p53 signaling. In phase 1 clinical studies, selinexor with low dose dexamethasone (Sd) demonstrated potent anti MM activity in pts with MM. Methods - This phase II clinical trial evaluated Sd in pts with MM refractory to bortezomib, carfilzomib, lenalidomide, and pomalidomide ("quad"), with a subset also refractory to an anti-CD38 Ab ("penta"). Inclusion required CrCL≥20 mL/min, ANC≥1000/µL, platelets ≥50K/µL (≥30K if plasma cells were ≥50% of marrow cellularity). Pts were treated twice weekly (BIW) with oral selinexor 80 mg for 6 or 8 doses per 28 day cycle and dexamethasone (dex) 20 mg BIW. All pts received 5-HT3 antagonists. The primary objective was to determine the overall response rate (ORR) per IMWG criteria and duration of response (DOR), both adjudicated by an independent review committee (IRC). Secondary endpoints include progression free survival (PFS) and overall survival (OS). FISH analyses and gene expression profiling were performed on bone marrow aspirates. Results - 79 pts were enrolled: 48 quad (24 M/24 F, median age 62 yrs) and 31 penta (13 M / 18 F, median age 68 yrs). Both groups had a median of 7 prior treatment regimens including multiple dex-containing regimens. Baseline laboratory abnormalities included grade (Gr)≥3 anemia in 13% and Gr≥3 thrombocytopenia in 8%. Most penta pts received 8 doses / cycle (65%); most quad pts received 6 doses / cycle (83%). Common treatment-related adverse events (TRAEs) hematological: thrombocytopenia (72%, Gr 3/4 58%), anemia (48%, Gr 3 25%) and neutropenia (29%, Gr≥3 21%). TRAEs non-hematological: nausea (72%, Gr 3 6%), fatigue (62%, Gr 3 14%) anorexia (49%, Gr 3 3%), vomiting (43%, Gr3 4%), asymptomatic hyponatremia (42%. Gr 3 20%), diarrhea (42%, Gr 3 5%) and weight loss (33%, Gr 3 1%). There was one case of febrile neutropenia (1%) and one case of clinically significant bleeding related to thrombocytopenia (1%). Seventy pts have discontinued therapy: PD (73%), AEs (17%), physician/pt preference (1%) and 6 deaths (one case related to selinexor, intracranial bleed in pt with Gr4 thrombocytopenia). Nine pts remain on study. Efficacy was evaluated in 78 pts (1 pt did not have measurable disease). The IRC-determined ORR (≥PR) for all pts was 21%, including 5% VGPR. ORR was 21% for quad pts and 20% for penta pts. Clinical benefit rates (≥MR) were 32% (all), 29% (quad), and 37% (penta). Median OS was 9.3 months (mo) for all pts, 〉11 mo (median not reached) for responders (≥PR), and 5.7 mo for non-responders. Median DOR in responding pts was 5 mo, and median PFS in all pts was 2.1 mo. Baseline cytogenetics were assessed in 41 pts. The ORR in 18 pts with high-risk FISH abnormalities was 33% (Table 1). Notably, 3 of the 13 pts with a 17p abnormality responded (ORR 23%). Transcriptomic profiling revealed differentially expressed genes (DEGs) between responders and non-responders in both whole blood RNA and CD138+ bone marrow cells. Pathways enriched in responders included IL-6, IL-8 and IGF-1 pathways. Conclusions - Oral Sd is active in heavily pretreated pts with refractory MM, including those with MM refractory to anti-CD38 Ab and those with high-risk cytogenetic abnormalities. Response was associated with longer survival. The main toxicities of Sd are thrombocytopenia, nausea, anorexia, and fatigue. AEs were manageable with supportive care and dose interruptions/reductions. To our knowledge, this is the first report of anti-tumor activity in the penta-refractory MM population. This population of MM pts has exhausted all currently available treatment options and has an extremely poor prognosis and therefore requires new therapies. Expansion of this trial in this high unmet medical need, penta refractory population is planned. Table 1 Activity of Sd in Patients with High Risk MM Cytogenetics Table 1. Activity of Sd in Patients with High Risk MM Cytogenetics Disclosures Vogl: Constellation: Research Funding; Karyopharm: Consultancy; Acetylon: Research Funding; GSK: Research Funding; Calithera: Research Funding; Teva: Consultancy; Celgene: Consultancy; Takeda: Consultancy, Research Funding. Jagannath:Bristol-Myers Squibb: Consultancy; Janssen: Consultancy; Novartis: Consultancy; Merck: Consultancy; Celgene: Consultancy. Baz:Bristol-Myers Squibb: Research Funding; Takeda/Millennium: Research Funding; Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Signal Genetics: Research Funding; Novartis: Research Funding; Karyopharm: Research Funding; Merck: Research Funding. Nooka:Spectrum, Novartis, Onyx pharmaceuticals: Consultancy. Richter:Takeda: Consultancy, Speakers Bureau; Amgen: Consultancy, Speakers Bureau; Celgene: Consultancy, Speakers Bureau; Janssen: Speakers Bureau; Bristol-Myers Squibb: Speakers Bureau; Novartis: Speakers Bureau. Vij:Karyopharm: Honoraria; Amgen: Honoraria, Research Funding; Celgene: Consultancy; Takeda: Honoraria, Research Funding; Novartis: Honoraria; Bristol-Myers Squibb: Honoraria; Janssen: Honoraria. Schiller:Incyte Corporation: Research Funding. Costa:Sanofi: Honoraria, Research Funding. Chari:Array Biopharma: Consultancy, Research Funding; Takeda: Consultancy, Research Funding; Celgene: Consultancy, Research Funding; Pharmacyclics: Research Funding; Janssen: Consultancy, Research Funding; Amgen Inc.: Honoraria, Research Funding; Novartis: Consultancy, Research Funding. Siegel:Takeda: Honoraria, Speakers Bureau; Novartis: Honoraria, Speakers Bureau; Amgen: Honoraria, Speakers Bureau; Celgene: Honoraria, Speakers Bureau; BMS: Honoraria, Speakers Bureau; Merck: Honoraria. Fonseca:Janssen: Consultancy; AMGEN: Consultancy; Millennium, a Takeda Company: Consultancy; Bayer: Consultancy; Sanofi: Consultancy; Patent Pending: Patents & Royalties: The use of calcium isotopes as biomarkers for bone metabolisms; Patent: Patents & Royalties: Prognostication of MM based on genetic categorization of FISH of the disease; AMGEN: Consultancy; Novartis: Consultancy; Millennium, a Takeda Company: Consultancy; Sanofi: Consultancy; AMGEN: Consultancy; Janssen: Consultancy; BMS: Consultancy; Celgene: Consultancy; BMS: Consultancy; Millennium, a Takeda Company: Consultancy; Millennium, a Takeda Company: Consultancy; Patent: Patents & Royalties: Prognostication of MM based on genetic categorization of FISH of the disease; Bayer: Consultancy; Novartis: Consultancy; Patent Pending: Patents & Royalties: The use of calcium isotopes as biomarkers for bone metabolisms; AMGEN: Consultancy; Patent: Patents & Royalties: Prognostication of MM based on genetic categorization of FISH of the disease; Patent: Patents & Royalties: Prognostication of MM based on genetic categorization of FISH of the disease; Patent Pending: Patents & Royalties: The use of calcium isotopes as biomarkers for bone metabolisms; Patent Pending: Patents & Royalties: The use of calcium isotopes as biomarkers for bone metabolisms; Celgene: Consultancy. Kauffman:Karyopharm Therapeutics Inc: Employment, Equity Ownership, Membership on an entity's Board of Directors or advisory committees. Shacham:Karyopharm Therapeutics: Employment, Equity Ownership, Membership on an entity's Board of Directors or advisory committees. Saint-Martin:Karyopharm: Employment. Picklesimer:Karyopharm: Employment. Friedlander:Karyopharm Therapeutics: Employment. Choe-Juliak:Karyopharm Therapeutics: Employment.

Description: Introduction - Selinexor is a first-in-class Selective Inhibitor of Nuclear Export (SINE) compound that binds and inactivates Exportin 1 (XPO1). Selinexor with low dose dexamethasone (dex) has demonstrated potent anti-cancer activity in patients with heavily pretreated MM. While the development of proteasome inhibitors (PIs) has transformed the treatment of MM, acquired resistance to PIs limit their efficacy. Preclinical studies have shown that selinexor, when combined with bortezomib, can restore sensitivity of bortezomib-resistant MM to this drug, inducing tumor growth inhibition and increasing survival in MM models in mice. In this clinical trial (NCT02343042), we investigated the safety, tolerability and efficacy of the combination of selinexor, bortezomib and low dose dex (SdB) in patients (pts) with refractory MM. Methods - This phase 1b/2 dose escalation study using a standard 3+3 design, was designed to determine the maximum tolerated dose (MTD) and recommended phase 2 dose (RP2D) for SdB. The study included pts with refractory MM, after ≥ 1 prior therapy. Pts with prior PI relapsed and/or refractory disease were included, provided the patient's MM was not refractory to bortezomib as last therapy. Selinexor was independently dosed escalated in once-weekly (QW, starting at 80 mg; N=7, 100 mg N=6 pts) or twice-weekly (BIW, starting at 60 mg; N=3, 80 mg N=6 pts) regimens. Bortezomib (1.3 mg/m2 sc) was administered either once-weekly or twice-weekly and dex was given orally 40 mg QW or 20 mg BIW. Results - As of July 25th, 2016, enrollment in the dose escalation cohorts has been completed with 22 pts (12 male /10 female). The median age is 65 years (range, 46 - 74), with a median of 4 (range, 1 - 12) prior treatment regimens. One dose limiting toxicity (Grade 4 thrombocytopenia without bleeding) in the 80 mg BIW cohort was observed but the MTD has not been reached. Common related grade 1/2 adverse events (AEs) include: fatigue 41%, nausea 41%, anorexia 36%, and weight loss 18%. Grade 3/4 AEs include: thrombocytopenia 41%, anemia 18%, and neutropenia 18%. One case of grade 1 peripheral neuropathy in the 80 mg BIW cohort was reported. All pts were evaluable for response. The ORR (≥partial response, PR) was 77% with ≥VGPR 27% (1 pt in CR and 5 pts in VGPR) and 11 PRs. There were 3 minor responses (14%), 1 stable disease, 1 progressive disease (5% each). Seven of the 12 pts with PI-refractory MM responded (ORR 58%). A summary of response by PI treatment history is shown in Table 1. Ten patients have remained on study 〉4 months, including 7 patients still on trial (longest 〉9 months). Based on tolerability and anti-MM activity, RP2D of SdB is selinexor 100 mg, bortezomib 1.3 mg/m2 and dex 40 mg, all given once weekly. At the RP2D, all six pts achieved ≥PR (ORR 100%). Conclusions - Selinexor in combination with bortezomib and dex is well tolerated and highly active in refractory MM. Toxicities are manageable and similar to selinexor or bortezomib monotherapy. Peripheral neuropathy is uncommon, consistent with the use of weekly bortezomib sc and the lack of neuropathy with selinexor. Overall, the SdB regimens induced an ORR of 77% with ≥VGPR of 27%. In patients with PI-refractory MM, the ORR was 58%, indicating that the addition of selinexor restores sensitivity to bortezomib. These results confirm the preclinical data supporting synergistic effects of selinexor when combined with PIs. This promising, once-weekly treatment regimen may provide deeper and more durable responses in pts with relapsed / refractory MM, including those with PI-refractory disease. Table 1. Best Response by Prior Proteasome Inhibitor (PI) Treatment Status Table 1. Best Response by Prior Proteasome Inhibitor (PI) Treatment Status Disclosures Bahlis: Onyx: Consultancy, Honoraria; Amgen: Consultancy, Honoraria; Celgene: Consultancy, Honoraria, Other: Travel Expenses, Research Funding, Speakers Bureau; Janssen: Consultancy, Honoraria, Other: Travel Expenses, Research Funding, Speakers Bureau; BMS: Honoraria. Sebag:Janssen: Honoraria; Novartis: Honoraria; Celgene: Honoraria. Sutherland:Amgen: Consultancy, Honoraria; Celgene: Consultancy, Honoraria; Janssen: Consultancy, Honoraria. White:Celgene: Consultancy, Honoraria; Janssen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees. Venner:Amgen: Honoraria; J+J: Research Funding; Takeda: Honoraria; Janssen: Honoraria; Celgene: Honoraria, Research Funding. Kouroukis:Amgen: Research Funding; Janssen: Research Funding; Karyopharm: Research Funding. McCurdy:Celgene: Honoraria. Lalancette:BMS: Honoraria; Celgene: Honoraria. Bensinger:Sanofi: Consultancy, Research Funding; Celgene: Consultancy, Honoraria, Research Funding; Acetylon: Research Funding; Takeda: Honoraria, Research Funding; Bayer: Research Funding; Bristol Myers Squibb: Consultancy, Research Funding; Amgen: Consultancy, Honoraria, Research Funding. Lentzsch:BMS: Consultancy; Celgene: Consultancy, Honoraria. Kauffman:Karyopharm Therapeutics Inc: Employment, Equity Ownership, Membership on an entity's Board of Directors or advisory committees. Shacham:Karyopharm Therapeutics: Employment, Equity Ownership, Membership on an entity's Board of Directors or advisory committees. Jeha:Karyopharm: Employment. Picklesimer:Karyopharm: Employment. Saint-Martin:Karyopharm: Employment. Choe-Juliak:Karyopharm Therapeutics: Employment. Chen:Celgene: Honoraria, Research Funding; Janssen: Honoraria, Research Funding; Takeda: Research Funding.