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8011 Background: The addition of a monoclonal antibody to triplet induction regimens in patients (pts) with MM with intent for autologous stem cell transplant (ASCT) has resulted in higher overall and deep response rates. In this study we are investigating the impact of the addition of Elo to KRd on complete response (CR) and/or MRD-negative rates in newly diagnosed MM regardless of transplant eligibility. Methods: Pts were enrolled from four MM Research Consortium sites into this phase 2 study. All patients receive 12 cycles of Elo-KRd in 28-day cycles: Elo per standard dosing, K 20/56/70 mg/m2 days 1, 8 and 15, R 25 mg days 1-21, and dexamethasone 40 mg days 1, 8, 15, 22. ASCT eligible candidates can undergo stem cell collection after cycle 4 and then resume treatment; pts who elect to proceed to ASCT are censored for response at that time. Pts MRD(-) (-5) by NGS after cycles 8 (C8) and 12 (C12) proceed to Elo-Rd until progression. Patients who convert from MRD(+) to MRD(-) between C8 and C12 receive an additional 6 cycles of Elo-KRd (total 18 cycles) followed by Elo-Rd, and pts MRD(+) after C12 receive an additional 12 cycles of Elo-KRd (total 24) followed by Elo-Rd. The primary endpoint of the study is sCR and/or MRD(-) rate after C8 E-KRd. MRD status was determined by ClonoSEQ next generation sequencing (NGS, -5) [Adaptive Biotechnologies]. An improvement in the sCR and/or MRD(-) rate by NGS from a historical 30% to 50% at the end of C8 will be considered promising. Results: 44 pts are enrolled, 39 of whom are evaluable for response (cutoff Jan 10 2021). Median age is 62 years (range 43-81, 23% age >70) and 23 (52%) have high-risk cytogenetic abnormalities (HRCA) including 13 (30%) with >2 high-risk abnormalities (6 pts unknown cytogenetics). 34/39 (87%) have MRD trackable by clonoSEQ. The rate of sCR and/or MRD(-) by NGS at the end of C8 is 19/33 (58%), meeting the statistical threshold for establishing efficacy (2 pts censored for elective ASCT before C8 and 4 pts receiving therapy but have not reached C8). With a median follow-up of 24 months, estimated 2-year progression free survival is 87% (100% for standard risk, 79% for HRCA) and estimated 2-year overall survival is 89% (82% for HRCA). No pt who was MRD(-) by NGS after C8 has progressed, including 6 pts with HRCA. Serious adverse events occurred in 30 pts (68%). 89% experienced treatment emergent AEs, the most common (>10%) of which was pneumonia (14%). One pt had grade 5 myocardial infarction. Conclusions: Elo-KRd demonstrates tolerability consistent with known toxicities of these agents and met the primary endpoint of sCR and/or MRD(-) of >50% after 8 cycles. With longer follow-up, the study results may validate that an MRD-adaptive design for de-escalation of therapy in MM can generate deep responses while reducing treatment exposure. Clinical trial information: NCT02969837.

Introduction: Lenalidomide (LEN) is a cornerstone in the treatment of newly diagnosed MM both as part of induction and maintenance therapy. As a result, most patients at first or second relapse are LEN exposed/refractory creating a need for effective 2nd line and salvage therapies. While no standard of care regimen has been established in early relapse, several therapies have been evaluated combining second generation immunomodulatory agents, proteasome inhibitors, and daratumumab. We have previously reported the results from the phase I/II trial of KPd demonstrating excellent efficacy in a LEN-refractory patient population. Here, we present the first efficacy and safety results from the cohort in which DARA was added to KPd (D-KPd). Methods: This is a multi-center, open-label, Phase 1b/2 study in subjects with relapsed MM with two sequential treatment cohorts: KPd and D-KPd. Eligibility criteria and KPd doses and schedules were identical for both cohorts. Subjects with measurable disease that progressed after at least 1 prior therapy (LEN refractory disease was required for 2nd-line therapy and LEN refractory/exposed for ≥ 3rd line) were eligible. The KPd cohort has completed enrollment (n=67) and results have been previously reported. The D-KPd cohort received treatment on the following 28-day schedule: Pomalidomide 4 mg daily on days 1-21 for cycles 1-8+, Carfilzomib 20/27 mg/m2 on days 1,2,8,9,15,16 for C1-8, then 1,2,15,16 for C9+ (maintenance), dexamethasone 20 mg days 1,2,8,9,15,16,22,23 for C1-2, then 40 mg days 1,8,15,22 for C3+. DARA was administered as per standard schedule, weekly for the first 2 cycles, then every 2 weeks for cycles 3-6, and monthly thereafter. A Minimax two-stage design was employed for enrollment of subjects on this cohort. Twenty-one patients were required to accrue to the first stage, with at least 4 responders of ≥nCR at 4 cycles necessary to accrue to second stage for a total of 34 pts. Primary endpoint was rate of nCR/CR as per IMWG criteria. Minimal residual disease (MRD) was evaluated by 10-color flow cytometry with limit of detection (LOD) 10-4-10-5 and will also be assessed by next-generation sequencing (LOD 10-5-10-6). Secondary endpoints include overall response rate, depth of response, progression-free survival (PFS), and overall survival. Per study design, a nCR/CR rate of >35% (over the historical 20% rate) would support further study of the D-KPd regimen. Results: As of July 29, 2020, all 22 subjects who were enrolled into the D-KPd cohort were evaluable for safety and the primary endpoint. Median age was 62 (range 37-74) with a median of 1 (range 1-3) prior lines of therapy. 81% of patients were LEN refractory, and high-risk cytogenetics per IMWG criteria were present in 12/19 (68%) evaluable patients. Subjects completed a median of 12.5 cycles (range 2-33) of therapy and 21 (95%) subjects completed at least 4 cycles; 1 subject progressed after cycle 2. In the ITT population (n=22), after 4 cycles, 86% achieved ≥PR and 46% ≥nCR, warranting further enrollment to a second stage. At best response, the ≥PR was 86% with 55% ≥nCR/CR, 45% ≥sCR, and 55% MRD negativity by flow cytometry (n=22). The most common grade 3-4 hematologic adverse events included neutropenia (64%), lymphopenia (36%), and febrile neutropenia (18%). The most common grade 3-4 non-hematologic adverse events included fatigue (27%), respiratory infections (23%), diarrhea (14%), and insomnia (14%). There was one thrombotic event (4.5%) which was grade 2. In comparison to the KPd cohort (67 patients with similar baseline characteristics), there was an improvement in efficacy as demonstrated by an increase in rate of ≥nCR at the end of 4 cycles (from 7% to 46%), as well as the best response (from 20% to 55%). High risk cytogenetics did not significantly affect response (≥nCR 46% at best response [all sCR]). With 20 months of follow-up, median PFS was not reached in the D-KPd cohort and 12-month PFS is 84% vs 63% for KPd. Rates of grade 3/4 cytopenias were higher in the D-KPd cohort. There was no treatment related mortality and 19 of 22 pts are alive. Conclusion: D-KPd demonstrates high efficacy in a population of patients with relapsed/refractory multiple myeloma enriched for high risk cytogenetics. MRD negativity by flow cytometry was achieved in 55% of subjects. The ≥nCR rate of 55% with D-KPd compares favorably to the 20% rate with KPd alone; based on the study design, this warrants further evaluation of D-KPd. Disclosures Zonder: BMS, Celgene: Research Funding; Intellia, Amgen, Takeda, Janssen, Regeneron, Alnylam, Caelum, Oncopeptides: Consultancy. Reece:Janssen, Bristol-Myers Squibb, Amgen, Takeda: Consultancy, Honoraria; Janssen, Bristol-Myers Squibb: Membership on an entity's Board of Directors or advisory committees; Merck: Honoraria, Research Funding; Otsuka: Research Funding. Berdeja:Kesios: Research Funding; Karyopharm: Consultancy; Acetylon: Research Funding; Vivolux: Research Funding; Abbvie: Research Funding; Amgen: Consultancy, Research Funding; Bioclinica: Consultancy; BMS: Consultancy, Research Funding; Celgene: Consultancy, Research Funding; Cellularity: Research Funding; Constellation: Research Funding; CURIS: Research Funding; EMD Sorono: Research Funding; Genentech, Inc.: Research Funding; Glenmark: Research Funding; Janssen: Consultancy, Research Funding; Kite Pharma: Consultancy; Legend: Consultancy; Lilly: Research Funding; Novartis: Research Funding; Poseida: Research Funding; Takeda: Consultancy, Research Funding; Teva: Research Funding; Prothena: Consultancy; Servier: Consultancy; Bluebird: Research Funding; CRISPR Therapeutics: Consultancy, Research Funding. Jakubowiak:Adaptive, Juno: Consultancy, Honoraria; AbbVie, Amgen, BMS/Celgene, GSK, Janssen, Karyopharm: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees.

Up to 40% of breast cancers have been shown to express the glucocorticoid receptor (GR), and activation of the GR is associated with poor prognosis in ER-negative breast cancer. We hypothesize that GR activation in breast cancer cells initiates anti-apoptotic signaling contributing to chemotherapy resistance. Based on our compelling preclinical data demonstrating that GR antagonism with mifepristone (mif) increases paclitaxel (pac) induced breast cancer cell death in vitro and in vivo, we conducted the first clinical trial of the combination of anti-GR therapy and chemotherapy in patients (pts) with metastatic breast cancer (MBC). Because the combination of mif and nab-paclitaxel (nab) had not previously been administered to pts, and because nab can result in cumulative neurotoxicity, a randomized, placebo-controlled, phase I design was used. Mif is known to inhibit CYP2C8, an enzyme involved in the metabolism of pac, thus plasma pac levels were monitored to evaluate for significant changes in clearance. A 3+3 dose escalation scheme was planned, with an initial nab dose of 100mg/m2 weekly and a mif dose of 300 mg/d for 2 days (day prior to and of nab infusion). For each dose level (DL), patients were randomized 3:2 to mif:placebo (p) for cycle 1 (C1). After C1, pts randomized to p were crossed over to receive mif at their assigned DL for the duration of study treatment. DL1 was deemed intolerable due to neutropenia, so the nab dose was decreased to 80 mg/m2 for DL2, and dose escalation of mif beyond 300 mg was halted. Serum cortisol and ACTH levels—biomarkers of effective GR blockade—were measured before and after mif treatment. Archival tumor was collected to determine tumor GR expression, and peripheral blood lymphocytes (PBLs) were collected to evaluate GR-target gene expression after mif. 9 pts were enrolled. Median age was 56 yrs (range 47-74). Median number of prior therapies for MBC was 2 (range 0-3). 8 pts had triple-negative breast cancer (TNBC), and 1 had ER+ disease. 8 of 9 pts had recurred after taxane-based therapy. 1 pt had a CR, 4 pts a PR, and 4 pts POD. 4 of 5 pts who responded to nab plus mif had previously relapsed after taxane-based therapy. 4 pts were treated at DL1 (2 mif, 2 p). Both pts randomized to mif experienced a dose-limiting toxicity (DLT) of neutropenia during C1. 5 pts were treated at DL2 (3 mif, 2 p), and 2 of the 3 pts randomized to mif for C1 experienced a DLT (neutropenia). Plasma pac levels were consistent with delayed clearance of nab when co-administered with mif for most pts. All pts were found to have a 2-fold or greater rise in their serum cortisol levels, demonstrating effective adrenal GR inhibition. Mif delays clearance of nab in most pts, and results in DLT. Given the inter-patient variability in delay of nab clearance by mif, co-administration produces unpredictable toxicity. However, given the responses seen in taxane-pretreated TNBC pts, GR antagonism is a promising approach for treating aggressive TNBCs. As neither carboplatin nor gemcitabine are metabolized, mif is unlikely to affect clearance of these agents. As they are widely used for advanced TNBC, both agents represent attractive chemotherapy partners for future clinical investigation. Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P2-16-21.

Purpose Glucocorticoid receptor (GR) overexpression is associated with poor prognosis ER-negative breast cancer. GR antagonism with mifepristone increases chemotherapy-induced breast cancer cell death, therefore we conducted a phase I clinical trial of mifepristone and nab-paclitaxel in advanced breast cancer. Methods A novel randomized phase I design was used to assess the effect of mifepristone on nab-paclitaxel pharmacokinetics and toxicity. Patients were randomized to placebo or mifepristone for the first cycle; mifepristone was given to all for subsequent cycles. Results Nine patients were enrolled. All were found to have a twofold or greater increase in serum cortisol after mifepristone administration, reflecting effective GR inhibition. Neutropenia occurred at both nab-paclitaxel dose levels studied (100 and 80 mg/m2), and was easily managed with dose reduction and/or growth factor administration. Pharmacokinetic data suggest an interaction between nab-paclitaxel and mifepristone in some patients. Two patients had complete responses (CR), three partial responses (PR), one stable disease (SD), and three progressive disease (PD). Immunohistochemical staining for GR found six of nine tumors were GR-positive. All six GR-positive tumors were triple-negative at the time of recurrence. Of these six patients, two had CRs, two PRs, one SD, and one PD. Conclusions GR appears to be a promising target in TNBC, and GR inhibition plus chemotherapy produces manageable toxicity. While neutropenia was observed in some, a nab-paclitaxel dose of 100 mg/m2 plus mifepristone 300 mg was found to be tolerable, and a randomized phase II trial of nab-paclitaxel with/without mifepristone is planned in GR-positive advanced TNBC. Electronic supplementary material The online version of this article (doi:10.1186/s40064-016-2457-1) contains supplementary material, which is available to authorized users.

6013Background: Single agent VEGFR inhibitors and lenalidomide (L) have shown activity in advanced DTC, but combination therapy has not been evaluated. The goal of this study was to determine progr...

Introduction: The biology of DLBCL is complex, with a number of clinicopathologic and molecular features impacting outcome. MCT-1 is an oncogene that promotes lymphomagenesis via enhanced cell survival signaling, increased G1 cyclin/CDK activity and overriding cell cycle checkpoints; its expression is substantially elevated in DLBCL without a clear difference in germinal center versus non-germinal center subtypes. Our preliminary studies showed that 1) 85% of DLBCL samples have strong or increased expression of MCT-1via IHC, 2) MCT-1 knockdown induces apoptosis in cell lines, and 3) mutant MCT-1 protein expression attenuates the malignant phenotype via translational changes. (Dai Ca Res 2009 69(19): p. 7835-43) MCT-1 levels are directly regulated by MEK/ERK signaling, providing a rationale to test MEK pathway inhibition as a therapeutic target in DLBCL. AZD-6244 (ARRY-142886, selumetinib) is a novel second generation oral small molecule MEK inhibitor that induces dose dependent apoptosis in DLBCL cell lines and attenuates tumor growth in xenograft models. (Bhalla Blood 2011 118(4): p. 1052-61) In patients with solid tumors, AZD-6244 75mg twice daily has been established as the recommended phase II dose (RP2D). (Adjei JCO 2008 26(13): p. 2139-46) Methods: Eligible relapsed/refractory (R/R) DLBCL patients received AZD6244 hydrogen sulfate at a dose of 75 mg by mouth twice daily continuously for up to eight 28-day cycles or until disease progression or unacceptable toxicity. The primary objective of the study was overall response rate (ORR) with secondary objectives including safety, progression free survival (PFS), overall survival (OS) and pharmacodynamic (PD) analyses. The statistical design used a Simon two-stage design. Due to excessive early toxicity, the protocol was amended to reduce the dose to 50mg twice daily. Results : Sixteen R/R DLBCL pts (9 male, 7 female) with a median age of 70 years (range, 29-86 yrs), median 3 prior regimens (range, 0-6) were enrolled. Cell-of-origin was not prospectively determined, but only 3/10 pts were CD10 positive and 5/9 were MUM1 positive. The median Lactate Dehydrogenase (LDH) at study entry was 483 (range, 194-1128). Two patients withdrew consent prior to treatment exposure. Of 14 patients receiving at least one dose of selumetinib, two had stable disease and the remainder progressed. The median number of treatment cycles was one (range, 1-5). This was partly due to toxicity causing frequent dose interruptions of AZD-6244. Grade ³3 toxicities were observed in 37.5% (15.2 - 64.6%) and included anemia (44%), thrombocytopenia (25%), diarrhea (31%), transaminitis 44%), fatigue (44%); other infrequent toxicities included AV block, LV dysfunction, anorexia and rash. Median progression-free survival (PFS) in all patients was 34 days [95% CI 14-73 days]. Median overall survival (OS) was 129 days [CI 58-134 days]; all but 3 patients (including one patient lost to follow-up) have expired. Conclusion: Despite excellent preclinical rationale to test selective MEK antagonism as a means of modulating MCT-1 and MEK/ERK in DLBCL, AZD-6244 was not well tolerated and had limited clinical activity. Other MEK/ERK inhibitors with a more favorable toxicity profile and/or use of rational synergistic combination therapy should be considered to further evaluate the role of MEC inhibition in this heavily pretreated patient population. (Patel Cancer 2014 19(4): p. 799-805 (Supported by NCI contract N01-CM-2011-00071C) Disclosures Petrich: Seattle Genetics: Consultancy, Honoraria, Research Funding. Westin:Spectrum: Research Funding. Gordon:Northwestern University: Employment; Dr Leo I. Gordon: Patents & Royalties: Patent for gold nanoparticles pending.