Kurzfassung: Introduction: Patients newly diagnosed with classic Hodgkin lymphoma (CHL) have over 80% chance of remission with first-line chemotherapy, such as ABVD (adriamycin, bleomycin, vinblastine, dacarbazine) regime. However, 10-40% of patients relapse eventually and require salvage therapy. High-dose therapy with autologous stem cell transplantation (ASCT) remains the standard of care for patients with relapsed or refractory CHL, offering a cure rate of around 50%. This may be further improved to around 60% with post-transplant consolidation with brentuximab vedotin (BV). Post-SCT BV consolidation has been offered to all patients, regardless of the risk group, in British Columbia since late 2015. We set out to review the ASCT outcome in CHL patients in the recent decade at our institution. Methods: All adult patients who received ASCT for relapsed or refractory CHL between July 2011 and June 2020 were included in this retrospective analysis. Information pertaining to their demographics, disease characteristics, treatment history, transplant details, clinical outcomes and post-relapse therapy was obtained by review of electronic data. The data cut-off date was June 28, 2021. Survival outcomes were censored at the last known clinic visit for patients without relapse or death during follow up. Survival analysis was performed using Kaplan-Meier survival function and log-rank test. Pearson's chi-square test and ANOVA were used for comparison between cohorts. The statistical program used was Stata® version 16.1 (Texas, USA). Results: 114 patients underwent ASCT for relapsed/refractory CHL. Bulky disease and extranodal involvement were seen in 11% and 40% respectively at relapse. Looking at the 'high risk criteria' as defined in the AETHERA trial: 45/114 (40%) patients had primary refractory CHL, 21/114 (18%) had relapsed within 12 months of completing the front-line chemotherapy and 15/114 (13%) had relapsed beyond one year of completing initial treatment but with an extranodal disease. The most commonly used salvage chemotherapy regime was GDP (gemcitabine, dexamethasone, cisplatin; 111/114; 97%). 10/114 (9%) patients received BV after failing salvage chemotherapy pre-SCT. The median number of lines of therapy pre-SCT was two (range 2-5). 94/108 (98%) had a chemosensitive disease with 35/108 (32%) achieving complete remission. 6/108 (6%) patients had a progressive disease at the time of SCT. For the transplant, all patients had a peripheral blood stem cell source and the conditioning regime was either Carmustine/Etoposide/Cytarabine/Melphalan (76%) or Etoposide/Melphalan (24%). After median follow up of 62.2 months, 50/114 (44%) patients relapsed with median relapse-free survival of 20.2 months (range 0.9 - 113.5) and 16/114 (14%) died. The direct cause of death was lymphoma progression in all but three patients (PJP pneumonia, pulmonary fibrosis, traumatic subdural hematoma). Whereas only 4/51 (8%) patients (2 without relapse) received post-SCT BV consolidation via a compassionate access program between July 2011 and October 2015 (cohort 1), 45/63 (71%) patients (33 in remission) received routine BV consolidation between November 2015 and June 2020 (cohort 2). In cohort 2, 44% had primary refractory CHL compared to 33% in cohort 1 but the number of 'low risk' patients was similar at 29% (Table 1). The most common reason for no post-SCT BV consolidation in cohort 2 was patient refusal (7/18; 40%). Other causes included BV pre-SCT, early disease progression and patient comorbidities. Only 9/42 (21%) patients with available data in cohort 2 completed the planned 16 cycles of BV consolidation. The median number of cycles was 10.5 (range 1-16). The most common reasons for early termination of BV consolidation were peripheral neuropathy (22/33; 67%) and disease progression (9/33; 27%). There was no statistically significant difference in PFS or OS demonstrated between the two cohorts (Graphs 1, 2). Conclusion: After median follow up of 5 years, 86% of patients remain alive and 56% are alive in remission. In British Columbia, post-SCT BV consolidation has been widely adopted with over 70% of patients receiving at least one cycle since late 2015. Successful completion of post-SCT BV consolidation is, however, limited by a high rate of treatment-limiting peripheral neuropathy. Relapse-free survival benefit of routine post-SCT BV consolidation is not demonstrated in this single-centre cohort. Figure 1 Figure 1. Disclosures White: Novartis: Honoraria. Sutherland: Janssen: Consultancy, Research Funding; GSK: Research Funding; Karyopharm: Research Funding; Celgene: Consultancy; Amgen: Consultancy. Sanford: Abbvie: Membership on an entity's Board of Directors or advisory committees; Stellar: Membership on an entity's Board of Directors or advisory committees. Abou Mourad: Amgen: Consultancy; Paladin: Consultancy; Pfizer: Consultancy. Song: Amgen: Consultancy, Honoraria; Celgene: Consultancy, Honoraria, Research Funding; Janssen: Honoraria, Research Funding; Takeda: Consultancy, Honoraria; GlaxoSmithKline: Honoraria; Kite, a Gilead Company: Honoraria; Bristol Myers Squibb: Honoraria; Sanofi: Honoraria.

Kurzfassung: Introduction: BCMA targeted CAR T cell therapy has shown promising results in patients with relapsed/refractory multiple myeloma (MM). Herein, we report on the safety and efficacy of MCARH171, a second generation, human derived BCMA targeted autologous 4-1BB containing CAR T cell therapy, including a truncated epidermal growth factor receptor safety system (Smith EL. Mol Ther 2018). Methods: This is a phase I first in human, dose escalation trial of MCARH171. Patients received conditioning chemotherapy with cyclophosphamide (Cy) 3 gm/m2 as a single dose or fludarabine 30 mg/m2 daily and Cy 300 mg/m2 daily for 3 days followed by MCARH171 infusion in 1-2 divided doses. The trial followed a standard 3+3 design with 4 dose levels where patients received the following mean doses per cohort: (1) 72x106, (2) 137x106, (3) 475x106, (4) 818x106 viable CAR+ T cells. The primary objective was to demonstrate safety, and secondary objectives included efficacy and expansion, and persistence of CAR T cells using PCR from the peripheral blood. The last accrued patient received MCARH171 on Dec 6, 2017 and the data cut-off is July 16, 2018. The study is closed to accrual. Results: 11 patients with relapsed and/or refractory MM were treated. Median number of prior lines of therapy was 6 (range: 4-14), and all patients received prior therapy with a proteasome inhibitor, IMiD, anti-CD38 monoclonal antibody, and high dose melphalan/stem cell transplant. Nine (82%) patients had high-risk cytogenetics and 9 (82%) were refractory to their immediate prior line of treatment. One patient was not evaluable for DLTs given the need for early radiation and steroids for impending spinal cord compression by tumor. There are no DLTs reported. Cytokine release syndrome (CRS) grade 1-2 occurred in 4 patients (40%), grade 3 occurred in 2 (20%), and there was no grade 4-5 CRS. Grade 2 encephalopathy occurred in 1 patient (10%) in the setting of high fevers which resolved in less than 24 hours. There was no grade 3 or higher neurotoxicity observed. Tocilizumab was administered to 3 patients; 2 in cohort 2, and 1 in cohort 3. Laboratory values correlating with CRS reaching grade 3 or requiring Tocilizumab (N=4) compared to those with no or milder CRS (N=6) included peak CRP (mean: 28.5 vs 4.6 mg/dL, p 〈 0.001), IFNg (mean peak fold increase: 271 vs 11-fold, p 〈 0.0001), and peak IL6 before Tocilizumab, as IL6 elevation artificially increases after use (mean: 435 vs 68.7 pg/mL, p 〈 0.005). No significant change was seen in ferritin or fibrinogen compared to baseline. Overall response rate was 64% and the median duration of response was 106 days (range: 17 to 235 days). The peak expansion and persistence of MCARH171 as well as durable clinical responses were dose dependent. Patients who were treated on the first two dose cohorts (≤150 X106 CAR T cells) had a lower peak expansion in the peripheral blood (mean 14,098 copies/µL; N=6), compared to patients who were treated on the third or fourth dose cohort 3-4 (≥450 X106 CAR T cells; N=5), where the mean peak expansion was 90,208 copies/µL (p 〈 0.05). Among the 5 patients who received higher doses (450 X106), 5/5(100%) patients responded. The duration of responses was also related to the cell dose, with 3 of 5 patients (60%) treated in the cohorts receiving ≥450 X106 had clinical responses lasting 〉 6 months compared to only 1 of 6 (16.7%) patients who received lower doses. Two patien have ongoing responses (VGPR) at 7.5+ and 10+ months of follow up. To normalize for dose administered we compared the pharmacokinetics of only patients treated at dose levels 3-4 ( ≥450 X106 CAR T cells). Here, we demonstrate that peak expansion correlated to clinical efficacy, with the 3 durable responders all having peak expansion 〉 85,000 copies/µL (mean: 131,732 copies/µL); compared to transient responders, where the maximum peak expansion was 33,213 copies/µL (mean: 27,922; Figure 1). Conclusions: MCARH171 has an acceptable safety profile with no DLTs reported. A dose-response relationship with toxicity was not clearly observed, as noted by distribution of tocilizumab use across dose cohorts. However, a dose-response relationship was observed with promising clinical efficacy at dose levels of ≥450 X106 CAR T cells. Controlling for dose level, peak expansion correlated with durability of response. These results further support the development of CAR T cells for heavily pre-treated patients with relapsed and refractory MM. Disclosures Mailankody: Janssen: Research Funding; Takeda: Research Funding; Juno: Research Funding; Physician Education Resource: Honoraria. Korde:Amgen: Research Funding. Lesokhin:Takeda: Consultancy, Honoraria; Squibb: Consultancy, Honoraria; Janssen: Research Funding; Genentech: Research Funding; Serametrix, inc.: Patents & Royalties: Royalties; Bristol-Myers Squibb: Consultancy, Honoraria, Research Funding. Hassoun:Oncopeptides AB: Research Funding. Park:Juno Therapeutics: Consultancy, Research Funding; Amgen: Consultancy, Membership on an entity's Board of Directors or advisory committees; Pfizer: Consultancy; AstraZeneca: Consultancy; Adaptive Biotechnologies: Consultancy; Kite Pharma: Consultancy; Novartis: Consultancy; Shire: Consultancy. Sauter:Juno Therapeutics: Consultancy, Research Funding; Sanofi-Genzyme: Consultancy, Research Funding; Spectrum Pharmaceuticals: Consultancy; Novartis: Consultancy; Precision Biosciences: Consultancy; Kite: Consultancy. Palomba:Pharmacyclics: Consultancy; Celgene: Consultancy. Riviere:Fate Therapeutics Inc.: Research Funding; Juno Therapeutics, a Celgene Company: Membership on an entity's Board of Directors or advisory committees, Research Funding. Landgren:Takeda: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Amgen: Consultancy, Research Funding; Pfizer: Consultancy; Janssen: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Karyopharm: Consultancy; Merck: Membership on an entity's Board of Directors or advisory committees; Celgene: Consultancy, Research Funding. Brentjens:Juno Therapeutics, a Celgene Company: Consultancy, Membership on an entity's Board of Directors or advisory committees, Patents & Royalties, Research Funding. Smith:Celgene: Consultancy, Patents & Royalties: CAR T cell therapies for MM, Research Funding.

Kurzfassung: Acute myeloid leukemia (AML) with TP53 mutation makes up ~13% of AML cases and is an aggressive, treatment-resistant subtype with dismal prognosis and limited therapeutic options. Aberrant activation of the Wnt signaling pathway is associated with AML initiation/progression and is required for the self-renewal and survival of leukemic stem cells, making Wnt signaling inhibition a potential therapeutic modality for adverse AML. CLKs regulate the activity of serine/arginine-rich splicing factors (SRSFs) that modulate spliceosome assembly, mRNA splicing, and gene expression. SM09419 is a novel, oral, small-molecule pan-CLK inhibitor that potently inhibits the Wnt pathway in a Wnt signaling reporter assay. The purpose of these studies was to examine the antitumor activity of SM09419 as a single agent and in combination with standard therapies in preclinical models of TP53 mutant (TP53mut) AML. In TF-1a and KG-1a AML cells with TP53 mutations, SM09419 dose-dependently inhibited SRSF6 phosphorylation and potently suppressed expression of Wnt-related genes (LEF1, MYC, DVL2) and proteins vs. vehicle. The effect of SM09419 on cell proliferation was tested in 6 TP53mut AML cell lines. Proliferation was strongly impaired by SM09419 across all cell lines (EC50=0.23 + 0.056 µM). SM09419 significantly induced apoptosis in TF-1a and KG-1a cells, increasing caspase 3/7 activation and PARP cleavage while reducing survivin and MCL-1 expression relative to vehicle. In addition, SM09419 potently inhibited cell proliferation when tested in 27 leukapheresis-derived human primary AML cell lines (EC50=0.046 + 0.0061 µM) regardless of TP53 status, cytogenetics, or AML diagnosis (de novo or relapsed/refractory). In vivo antitumor effects and tolerability of oral SM09419 (QD) alone or combined with cytarabine (Ara-C), venetoclax (VEN), or azacytidine (AZA) were assessed in mice bearing TP53mut flank xenografts (n=5-15/group). In TF-1a xenografts, SM09419 (12.5 and 25 mg/kg) induced significant tumor growth inhibition (TGI) vs. vehicle at D20 (TGI 55-56% [p 〈 0.01]). VEN (50mg/kg) was not effective (3% TGI) and combining VEN with SM09419 had no additional benefit (52%-60% TGI). In Kasumi-1 xenografts, SM09419 (12.5 and 25 mg/kg), AZA (0.8 mg/kg), and VEN (25 mg/kg) induced TGI vs. vehicle of 87%, 95% (both p 〈 0.0001), 72% (p 〈 0.001), and 48% (NS), respectively at D18. SM09419 25 mg/kg alone induced tumor regression in 40% (2/5) of the mice. SM09419 (12.5 mg/kg) + VEN induced greater TGI vs. vehicle (96%, p 〈 0.0001) with tumor regression in 80% (4/5) of the mice, while AZA + VEN induced 79% TGI (p 〈 0.001) with no tumor regression. In KG-1a xenografts, single-agent SM09419 (12.5 and 25 mg/kg) and Ara-C (10mg/kg) induced significant TGI vs. vehicle (53%, 98%, and 80% [p 〈 0.001], respectively) at D28 but VEN (12.5mg/kg) did not (35% TGI). The combination of SM09419 (12.5 mg/kg) + VEN (12.5 mg/kg) improved TGI (98%) vs. vehicle. Tumor regression was seen in all mice with single-agent SM09419 (25 mg/kg) and 12.5 mg/kg + VEN. In another KG-1a xenograft study, mice were treated with combinations of SM09419 (12.5 mg/kg), AZA (0.8 mg/kg), and VEN (25 mg/kg) for 20 days followed by 21 days of SM09419 (25 mg/kg) or vehicle maintenance in some groups. SM09419 + VEN, SM09419 + AZA, and AZA + VEN induced TGI of 95%, 64%, and 58%, respectively (all p 〈 0.0001), with 80% (12/15) regression in SM09419 + VEN. The triplet induced 91% TGI but was not well tolerated due to GI toxicity. In the maintenance phase, SM09419 given QD or QOD greatly slowed tumor regrowth vs. vehicle at D41 in mice previously treated with SM09419 + VEN (80% and 72% TGI [p 〈 0.001], respectively). SM09419 QD maintenance therapy also slowed tumor regrowth following AZA + VEN (p 〈 0.0001). SM09419 alone and in combination (except with AZA + VEN) was well tolerated in all tested xenografts. In summary, SM09419 potently inhibited SRSF phosphorylation and Wnt pathway signaling and induced apoptosis in TP53mut AML cell lines. It also inhibited proliferation in cell lines and primary AML cells regardless of TP53 status. Strong in vivo antileukemic effects were observed with SM09419 as a single agent or in combination with other AML therapies, suggesting that it is a potential treatment for hard-to-treat AML subtypes such as TP53mut AML. A Phase 1 study assessing safety, tolerability, and pharmacokinetics of SM09419 in subjects with advanced hematologic malignancies is being initiated. Disclosures Chung: Samumed, LLC: Employment, Equity Ownership. Creger:Samumed, LLC: Employment, Equity Ownership. Sitts:Samumed, LLC: Employment, Equity Ownership. Chiu:Samumed, LLC: Employment, Equity Ownership. Mak:Samumed, LLC: Employment, Equity Ownership. KC:Samumed, LLC: Employment, Equity Ownership. Tam:Samumed, LLC: Employment, Equity Ownership. Bucci:Samumed, LLC: Employment, Equity Ownership. Stewart:Samumed, LLC: Employment, Equity Ownership. Phalen:Samumed, LLC: Employment, Equity Ownership. Cha:Samumed, LLC: Employment, Equity Ownership.

Kurzfassung: B cells rapidly downregulate CD1d expression after EBV infection, thus abrogating iNKT cell recognition. EBV-infected B cells induced to express CD1d elicit iNKT cell functions even in the absence of exogenous antigen.

Kurzfassung: Hemorrhage remains the leading cause of preventable morality, resulting in the death of over a third of all trauma patients. Additionally, twenty-five percent of trauma patients present on admission with acute traumatic coagulopathy (ATC) which portends a mortality approaching fifty percent. ATC has been defined by multiple parameters including international normalized ratio (INR) 〉 1.2, rotational thromboelastometry (ROTEM) clot amplitude at 5 minutes (CA5) ≤ 35 mm and lysis at 60 minutes (LI60) ≤ 85%. Damage control resuscitation (DCR), the practice of the Joint Theater Trauma System in Iraq and Afghanistan, is based on rapid hemorrhage control, permissive hypotension and transfusion of blood products in a ratio that aims to deliver the functionality of whole blood (1:1:1, red cells:plasma:platelets), in addition to limiting crystalloid resuscitation. ROTEM defined ATC has not been observed over time among DCR eligible combat casualties. The goal of this study was to identify ATC and the effects of DCR in trauma patients treated at level III trauma hospitals in Afghanistan. In this prospective observational study, 88 trauma patients were treated at Craig Air Force Theatre Hospital – Bagram, or Kandahar NATO Hospital in the Afghanistan Theatre. We included only patients from coalition forces identified as having injury that would result in the loss of life or total disability resulting in activation of DCR. Blood was obtained for analysis upon admission and at 6 and 24 hours after admission by a designated research team. Blood was analyzed by ROTEM with multiple assays (EXTEM, FIBTEM, APTEM); however, data was not available to the treatment team. Complete blood counts and INR were also obtained and Injury Severity Scores (ISS) were determined. Transfusion requirements of red blood cells (RBCs), platelets (PLT), fresh frozen plasma (FFP) and cryoprecipitate were recorded for the first 24 hours following admission. ROTEM changes over time were analyzed using Wilcoxon signed-rank test. Forty patients in the cohort had ROTEM (EXTEM) data obtained for evaluation as equipment was unavailable during a portion of the study. The median ISS was 21.5 (IQR 14-27). Four of the patients in the cohort died. The median admission hemoglobin and hematocrit were 11.1 g/dL (IQR 10.1-12) and 32.3% (IQR 29-34.5) respectively. The median INR was 1.3 (IQR 1.2-1.4). The median patient RBC to FFP to PLT ratio was 1:1:0.8. The median clot time (CT) and maximum clot firmness (MCF) were 58.5 sec (IQR 51-65.5) and 56 mm (IQR 51-60.5) respectively. Median CA5 was 37.5 mm (IQR 31-45). ATC as identified by CA5 ≤ 35 mm was present in 15 of 40 patients (38%) upon admission. The median CA5 of patients who met criteria for ATC on admission was 26 mm (IQR 15-34) which improved to 38 mm (IQR 33-44) at 24 hours (p 〈 0.01). Median LI45 was 98% (IQR 96-99). Hyperfibrinolysis as defined by LI45 ≤ 85% was observed in 4 of 40 patients (10%) upon admission which did not change significantly at 24 hours. The incidence of acute traumatic coagulopathy as defined by ROTEM parameters in this high risk military cohort appears to be higher compared to that reported for civilian populations. These data suggest that current DCR practices including a 1:1:1 RBC:FFP:PLT ratio appropriately target high risk trauma patients with ATC and that this strategy appears to be associated with a reduction in the burden of coagulopathy by 24 hours. Disclosures No relevant conflicts of interest to declare.

Kurzfassung: Background: Multiple myeloma clinical trial CC-4047-MM-014 (NCT01946477) is a Phase II study designed to test the safety and efficacy of pomalidomide and low-dose dexamethasone alone (arm A) or in combination with daratumumab, an anti-CD38 antibody, (arm B) subjects with relapsed or refractory multiple myeloma who have received a first or second line treatment of lenalidomide-based therapy. Immunomodulatory agents (IMiD® compounds) continue to be the backbone of multiple myeloma therapy especially when combined with monoclonal antibodies, more specifically pomalidomide had been shown previously to enhance T cell- and NK cell-mediated immunity. We sought to characterize on-treatment pharmacodynamic changes of immune biomarkers associated with POM + LoDEX + DARA administration (arm B) using multicolor flow cytometry panels designed to characterize T-cell subsets and CD38+ expressing cells. IMiD agents are the backbone of combination regimens in the treatment of patients with newly diagnosed or relapsed and/or refractory multiple myeloma. The anti-myeloma properties of these agents derive from a dual mechanism of pro-apoptotic effects on tumor cells as well as enhanced immune stimulation. An understanding of how IMiD agents interact with new monoclonal antibodies to modify patient immune profiles offers key insights into the role of such in innate and adaptive immunity in determining patient outcomes. Methods and Results: Peripheral blood samples were collected at screening, Cycle1 Days 1, 8, and 15, and Cycle 2 Days 1 and 15 to monitor pharmacodynamic changes in populations of T cells, NK cells, monocytes and MDSCs by flow cytometry. From 112 patients enrolled in Arm B, 98 patients had baseline and post-treatment specimens available for these analyses. As expected, combination treatment with POM + LoDEX + DARA led to decreased peripheral counts of CD56+CD16+ NK cells as well as CD4+CD38+ and CD8+CD38+ T cell subpopulations. Decreased counts were also noted in CD3-CD19+ B cells. In contrast, total counts of CD14+ monocytes and CD3+CD4+ or CD3+CD8+ T cells were stably maintained and pronounced increases were observed in proliferating CD4+Ki-67+ and CD8+Ki-67+ T cells. Further, when examined as a percent of total counts, increases were observed in CD14+ monocytes, CD3+CD4+ and CD3+CD8+ T-cells, with decreases in CD3-CD19+ B-cells and CD3-CD56+CD16+ NK cells. Correlation of these pharmacodynamic changes with clinical outcomes will be presented. In addition, baseline immune profiling of specific cell population subsets and associations with best overall response and progression-free survival is currently being analyzed. Conclusions: The triplet regimen POM + LoDEX + DARA has shown notable clinical activity with deep and durable responses in relapsed multiple myeloma patients progressed and are or refractory to lenalidomide. Immune characterization here is consistent with a model for clinical activity in which the loss of CD56+CD16+ NK cells along with a concomitant immune suppression by loss of CD38+CD4+ and CD38+CD8+ T- cells is offset by an increase in proliferating cytotoxic CD4+Ki-67+ and CD8+Ki-67+ T-cell populations. Our results demonstrate that patients treated with the POM + LoDEX + DARA combination do not demonstrate impairment in the innate and adaptive immune compartments and, in contrast, show significant proliferative activity in the subsets of CD4, CD8 and NK cells following treatment. Pomalidomide had been shown previously to enhance T cell- and NK cell-mediated immunity; these data are consistent with a mechanism of action in which pomalidomide administration facilitates the ability to overcome immunosuppressive effects of Dara and LoDex. Potential associations of immune biomarkers with patient outcomes is ongoing and will be updated. Disclosures Pierceall: Celgene Corporation: Employment, Equity Ownership. Bahlis:Janssen: Consultancy, Honoraria, Research Funding; Celgene: Consultancy, Honoraria, Research Funding; Amgen: Consultancy, Honoraria, Research Funding. Siegel:Merck: Consultancy, Honoraria, Speakers Bureau; Celgene: Consultancy, Honoraria, Research Funding, Speakers Bureau; Karyopharm: Consultancy, Honoraria; Amgen: Consultancy, Honoraria, Speakers Bureau; BMS: Consultancy, Honoraria, Speakers Bureau; Novartis: Honoraria, Speakers Bureau; Janssen: Consultancy, Honoraria, Speakers Bureau; Takeda: Consultancy, Honoraria, Speakers Bureau. Schiller:Astellas Pharma: Membership on an entity's Board of Directors or advisory committees, Research Funding; bluebird bio: Research Funding. Sebag:Amgen Canada: Membership on an entity's Board of Directors or advisory committees; Takeda Canada: Membership on an entity's Board of Directors or advisory committees; Janssen Inc.: Membership on an entity's Board of Directors or advisory committees; Celgene Canada: Membership on an entity's Board of Directors or advisory committees. Berdeja:Takeda: Research Funding; Genentech: Research Funding; Sanofi: Research Funding; Bristol-Myers Squibb: Research Funding; Celgene: Research Funding; Janssen: Research Funding; Glenmark: Research Funding; Amgen: Research Funding; Novartis: Research Funding; Poseida Therapeutics, Inc.: Research Funding; Bluebird: Research Funding; Teva: Research Funding. Ganguly:Amgen: Consultancy; Daiichi Sankyo: Research Funding; Janssen: Consultancy; Seattle Genetics: Speakers Bureau. Matous:Celgene: Consultancy, Honoraria, Speakers Bureau. Srinivas:VAHCSNJ: Employment. Bar:Celgene: Consultancy. Quick:CTI BioPharma: Research Funding. Fonseca:Celgene: Speakers Bureau. Reece:Janssen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Celgene: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Amgen: Consultancy, Honoraria, Research Funding; Takeda: Consultancy, Honoraria, Research Funding; Merck: Honoraria, Research Funding; Otsuka: Research Funding. Serbina:Celgene: Employment. Zafar:Celgene: Employment. Agarwal:Celgene Corporation: Employment, Equity Ownership. Thakurta:Celgene Corporation: Employment, Equity Ownership.

Kurzfassung: Background: Pomalidomide (POM) in combination with low-dose dexamethasone (LoDEX) is approved for the treatment (Tx) of patients (pts) with multiple myeloma (MM) who have had ≥ 2 prior lines of therapy, including lenalidomide (LEN) and a proteasome inhibitor. Although LEN and POM are both IMiD® immunomodulatory agents, preclinical studies have shown that LEN is not cross-resistant with POM (Ocio et al, Leukemia, 2015) and that LEN-resistant myeloma cells remain sensitive to POM (Lopez-Girona et al, Leukemia, 2012). Furthermore, sub-analyses of the MM-002 and MM-003 trials demonstrated that POM + LoDEX had comparable efficacy in pts refractory to their last prior Tx with LEN as in the overall pt population (San Miguel et al, Lancet Oncol, 2013; Richardson et al, Blood, 2014). Here, we present an updated analysis of MM-014, a single-arm, phase 2 trial of POM + LoDEX in pts with MM relapsed or refractory to LEN-based second-line therapy. Methods: Pts were ≥ 18 years old with a documented diagnosis of MM, measurable disease, 2 prior lines of Tx, and progressive disease after ≥ 2 cycles of second-line Tx with a LEN-based therapy. The Tx regimen was POM 4 mg/day on days 1-21 and LoDEX 40 mg/day (20 mg/day for pts 〉 75 years old) on days 1, 8, 15, and 22 of a 28-day cycle; thromboprophylaxis was mandatory. Responses were assessed using modified International Myeloma Working Group criteria. The primary endpoint was overall response rate (ORR; ≥ partial response [PR] ). Secondary endpoints included time to response (TTR), duration of response (DOR), time to progression (TTP), progression-free survival (PFS), and overall survival (OS). Secondary primary malignancies (SPMs) were monitored and recorded as serious AEs regardless of relationship to Tx. Exploratory endpoints included measures to identify potential molecular, immune, and cellular biomarkers for POM + LoDEX response, resistance, or mechanism of action. Results: Of 51 enrolled pts (N = 85 planned), 16 (31.4%) remain on Tx, and 35 (68.6%) discontinued from Tx (n = 20 due to PD, n = 7 due to withdrawal by pt, and n = 2 each due to adverse event [AE], death, lack of efficacy, and other reasons). The median age was 68.0 years, and most pts (92.2%) had an Eastern Cooperative Oncology Group performance status of ≤ 1; 34 pts (66.7%) were refractory to their last Tx with LEN, and 37 (72.5%), 2 (3.9%), and 1 (2.0%) pts had prior Tx with bortezomib, carfilzomib, or ixazomib, respectively. A total of 33 pts (64.7%) had prior stem cell transplant. The median duration of the most recent prior LEN-containing Tx was 24.6 months, and the median study follow-up time was 11.4 months. The ORR was 31.4%, including 3.9% (n = 2) with complete response, 5.9% (n = 3) with very good PR, and 21.6% (n = 11) with PR. The clinical benefit rate (≥ minimal response) was 41.2%. Of the 16 pts who achieved ≥ PR, 12 (75.0%) have an ongoing response; median TTR in these pts was 1.9 months. The median DOR based on Kaplan-Meier estimates was not reached. The 1-year PFS, OS, and TTP rates were 60.2%, 87.4%, and 64.6%, respectively. Common (≥ 5%) grade 3/4 AEs included anemia (23.5%), neutropenia (13.7%), thrombocytopenia (9.8%), fatigue (7.8%), and infections (19.6%; including pneumonia [7.8%]). AEs of special interest (any grade) included pulmonary embolism (3.9%), deep vein thrombosis (2.0%), and peripheral sensory neuropathy (3.9%); no SPMs were observed. The immune subset analysis showed a significantly elevated proportion of CD3+/CD8+ T cells after Tx (cycle 3, 5, day 1) compared with baseline (37.6% vs 30.5% of total lymphocytes; P 〈 .01). A similar trend toward elevated proportions of CD3+ T cells (73.7% vs 66.6%) was observed; however, the difference was not significant. There was no significant change in CD3+/CD4+ T cells (35.9% vs 35.5%). Conclusions: This updated analysis of the MM-014 trial demonstrates the safety and efficacy of POM + LoDEX in pts who were relapsed or refractory to their last prior Tx with LEN. Results suggest that POM + LoDEX can be used immediately following LEN-based therapy to treat pts with relapsed/refractory MM. The study has been amended to include a cohort of pts treated with POM + LoDEX + daratumumab. Investigations of additional biomarkers, high-risk genetic aberrations, clonal evolution, and minimal residual disease in MM-014 are currently underway. Disclosures Siegel: Novartis: Honoraria, Speakers Bureau; Celgene: Honoraria, Speakers Bureau; Amgen: Honoraria, Speakers Bureau; BMS: Honoraria, Speakers Bureau; Takeda: Honoraria, Speakers Bureau; Merck: Honoraria. Schiller:Incyte Corporation: Research Funding. Song:Otsuka: Honoraria; Celgene: Honoraria, Research Funding; Janssen: Honoraria. Kaya:Celgene, Amgen, Takeda: Honoraria. Sebag:Janssen: Honoraria; Celgene: Honoraria; Novartis: Honoraria. Reu:Celgene, Novartis and Takeda: Research Funding; Signal Genetics, Inc.: Consultancy. Mouro:Celgene: Employment, Equity Ownership. Chung:Celgene: Employment. Srinivasan:Celgene: Employment; Individual Patent: Patents & Royalties: US7,495,673B1 Used for MM-Connect Treatment Patterns Abstract.. Qian:Celgene: Employment. Rizvi:Celgene: Employment, Equity Ownership. Thakurta:Celgene: Employment, Equity Ownership. Bahlis:Celgene: Consultancy, Honoraria, Other: Travel Expenses, Research Funding, Speakers Bureau; Amgen: Consultancy, Honoraria; Janssen: Consultancy, Honoraria, Other: Travel Expenses, Research Funding, Speakers Bureau; BMS: Honoraria; Onyx: Consultancy, Honoraria.