Breast tumor interleukin-6 (IL-6) levels increase with tumor grade, and elevated serum IL-6 correlates with poor breast cancer patient survival. Epithelial–mesenchymal transition (EMT) phenotypes such as impaired E-cadherin expression or aberrant Vimentin induction are associated with enhanced metastasis and unfavorable clinical outcome in breast cancer. Despite this fact, few tumor microenvironment-derived extracellular signaling factors capable of provoking such a phenotypic transition have been identified. In this study, we showed that IL-6 promoted E-cadherin repression among a panel of estrogen receptor-α-positive human breast cancer cells. Furthermore, ectopic stable IL-6 expressing MCF-7 breast adenocarcinoma cells (MCF-7IL–6) exhibited an EMT phenotype characterized by impaired E-cadherin expression and induction of Vimentin, N-cadherin, Snail and Twist. MCF-7IL–6 cells formed xenograft tumors that displayed loss of E-cadherin, robust Vimentin induction, increased proliferative indices, advanced tumor grade and undifferentiated histology. Finally, we showed aberrant IL-6 production and STAT3 activation in MCF-7 cells that constitutively express Twist, a metastatic regulator and direct transcriptional repressor of E-cadherin. To our knowledge, this is the first study that shows IL-6 as an inducer of an EMT phenotype in breast cancer cells and implicates its potential to promote breast cancer metastasis.

Key Points• Response to the CD38-targeting antibody daratumumab is significantly associated with CD38 expression levels on the tumor cells.• Resistance to daratumumab is accompanied by increased expression of complementinhibitory proteins.The anti-CD38 monoclonal antibody daratumumab is well tolerated and has high single agent activity in heavily pretreated relapsed and refractory multiple myeloma (MM). However, not all patients respond, and many patients eventually develop progressive disease to daratumumab monotherapy. We therefore examined whether pretreatment expression levels of CD38 and complement-inhibitory proteins (CIPs) are associated with response and whether changes in expression of these proteins contribute to development of resistance. In a cohort of 102 patients treated with daratumumab monotherapy (16 mg/kg), we found that pretreatment levels of CD38 expression on MM cells were significantly higher in patients who achieved at least partial response (PR) compared with patients who achieved less than PR. However, cell surface expression of the CIPs, CD46, CD55, and CD59, was not associated with clinical response. In addition, CD38 expression was reduced in both bone marrow-localized and circulating MM cells, following the first daratumumab infusion. CD38 expression levels on MM cells increased again following daratumumab discontinuation. In contrast, CD55 and CD59 levels were significantly increased on MM cells only at the time of progression. All-trans retinoic acid increased CD38 levels and decreased CD55 and CD59 expression on MM cells from patients who developed daratumumab resistance, to approximately pretreatment values. This resulted in significant enhancement of daratumumab-mediated complement-dependent cytotoxicity. Together, these data demonstrate an important role for CD38 and CIP expression levels in daratumumab sensitivity and suggest that therapeutic combinations that alter CD38 and CIP expression levels should be investigated in the treatment of MM. These trials were registered at www.clinicaltrials.gov as #NCT00574288 (GEN501) and #NCT01985126 (SIRIUS). (Blood. 2016;128(7):959-970)

Bone is the primary anatomical site of breast cancer metastasis, and bone metastasis is associated with increased morbidity and mortality. Mesenchymal stem cells (MSC) are a predominant fibroblast cell population within the bone marrow, and metastatic breast cancer cells that seed within bone would predictably encounter MSC or their soluble factors. Therefore, we examined the impact of primary human MSC on a panel of estrogen receptor-alpha (ERalpha)-positive (MCF-7, T47D, BT474, and ZR-75-1) and ERalpha-negative (MDA-MB-231 and MDA-MB-468) human breast tumor cell lines. All ERalpha-positive breast tumor cell lines displayed low basal activation of signal transducer and activator of transcription 3 (STAT3) until exposed to MSC, which induced chronic phosphorylation of STAT3 on tyrosine-705. Paracrine IL-6 was found to be the principal mediator of STAT3 phosphorylation in coculture studies, and MSC induction of STAT3 phosphorylation was lost when IL-6 was depleted from MSC conditioned media or the IL-6 receptor was blocked on tumor cells. Enhanced tumor cell growth rates were observed in the ERalpha-positive mammary tumor cell line MCF-7 after paracrine and autocrine IL-6 exposure, where MCF-7 growth rates were enhanced by >2-fold when cocultured with MSC in vitro and even more pronounced in vivo with autocrine IL-6 production.

Key Points• A pooled analysis of 2 daratumumab trials showed no new safety signals, an overall response rate of 31%, and deep and durable responses.• Median overall survival was 20.1 months; benefit was also shown in patients who achieved minimal response/ stable disease.The efficacy and favorable safety profile of daratumumab monotherapy in multiple myeloma (MM) was previously reported. Here, we present an updated pooled analysis of 148 patients treated with daratumumab 16 mg/kg. Data were combined from part 2 of a first-in-human phase 1/2 study of patients who relapsed after or were refractory to ‡2 prior therapies and a phase 2 study of patients previously treated with ‡3 ). The median progression-free survival (PFS) and overall survival (OS) were 4.0 months (95% CI, 2.8-5.6 months) and 20.1 months (95% CI, 16.6 months to NE), respectively. When stratified by responders vs stable disease/minimal response vs progressive disease/NE, median PFS was 15.0 months (95% CI, 7.4 months to NE) vs 3.0 months (95% CI, 2.8-3.7 months) vs 0.9 months (95% CI, 0.9-1.0 months), respectively, and median OS was NE (95% CI, NE to NE) vs 18.5 months (95% CI, 15.1-22.4 months) vs 3.7 months (95% CI, 1.7-7.6 months), respectively. No new safety signals were identified. In this pooled data set, daratumumab 16 mg/kg monotherapy demonstrated rapid, deep, and durable responses, with a clinical benefit that extended to patients with stable disease or better. (Blood. 2016;128(1):37-44)

Introduction : Daratumumab (DARA) is a novel human CD-38-targeting monoclonal antibody in clinical development for multiple myeloma (MM). In two clinical studies (NCT00574288 [GEN501] and NCT01985126 [Sirius]), DARA monotherapy showed remarkable clinical activity and was well tolerated in heavily treated patients (pts) with relapsed and refractory (RR) MM (Lokhorst HM. J Clin Oncol 2014;32 Suppl:abstr 8513. Lonial S. J Clin Oncol 2015;33 Suppl: abstr LBA8512). A combined analysis of efficacy of 16 mg/kg DARA in these two studies is presented. Methods : GEN501, a first-in-human open-label, two-part (Part 1 dose escalation; Part 2 dose expansion) study, enrolled pts with MM that had relapsed after or were refractory to ≥2 prior therapies. Sirius, an open-label, two-part study, enrolled pts with MM with ≥3 prior therapies, including a PI or IMiD, or were refractory to both a PI and an IMiD. Eligibility criteria included pts with absolute neutrophil count ≥1000/mm3, hemoglobin ≥7.5 g/dL, platelet count ≥75×109/L (GEN501) or ≥50×109/L (Sirius), and alanine aminotransferase ≤3.5 (GEN501) or ≤2.5 (Sirius) times the upper limit of normal. In GEN501 Part 2, the first 16 mg/kg DARA infusion was followed by a 3 week rest period, and then qw for 7 weeks, q2w for 14 weeks, and q4w thereafter. In Sirius, 16 mg/kg DARA was infused qw for 8 weeks, q2w for 16 weeks, and q4w thereafter. The combined analysis comprised pts treated with 16 mg/kg DARA in Sirius and Part 2 of GEN501. In both studies overall response rates (ORR) were assessed according to IMWG response criteria. Results: The combined analysis included 148 pts (42 and 106 pts from GEN501 and Sirius, respectively). The median (range) age was 64 (31-84) years. Median time since initial diagnosis was 5.8 and 4.8 years in GEN501 and Sirius, respectively, and 62% and 82% of pts had received >3 prior therapies, respectively. In GEN501, 76% of pts were refractory to their last therapy and 64% were refractory to both a PI and IMiD; a greater proportion of pts in Sirius were refractory to their last therapy (97%) and double refractory to a PI and IMiD (95%). The ORR was 36% in GEN501 and 29% in Sirius; the ORR for the combined analysis was 31%. Best overall response is shown in Table. Responses deepened over time and the combined rate of very good partial response (VGPR) or better was 11% with 2 pts with complete responses (CR) and 3 with stringent CRs (sCR) across the two studies. In the combined analysis, median duration of response was 7.6 months and 46% of responders remained progression free at 1-year after a median follow-up of 9.3 months. Median overall survival (OS) had not been reached at median follow-up times of 10.2 months (GEN501) and 9.3 months (Sirius). The estimated 1-year OS rate (95% CI) was 77% (58-88), 65% (51-76), and 69% (58-77) for GEN501, Sirius, and the combined analysis, respectively. Forty-four of 46 responders were still alive at the time of the primary analysis. At a subsequent data cutoff for the combined analysis, after a median follow-up of 14.8 months, the estimated median OS was 19.9 months (95% CI, 15.1 - not estimable). ORR was similar across prespecified subgroups which included age, ISS stage, number of prior therapies, and refractory status. Conclusions : Single-agent DARA (16 mg/kg) demonstrated remarkable clinical activity (31% ORR) in a combined analysis of two studies in heavily pretreated MM pts. The quality of the observed responses (11% VGPR or better, 2 CRs, and 3 sCRs) was noteworthy in this highly refractory population. DARA shows promising activity in pts who have exhausted other approved myeloma treatment options. Table. Best Overall Response. 16 mg/kg MMY2002 n (%) GEN501 Part 2 n (%) Total n (%) Combined analysis set 106 42 148 Best response Stringent Complete Response (sCR) 3 (2.8) 0 3 (2.0) Complete response (CR) 0 2 (4.8) 2 (1.4) Very good partial response (VGPR) 10 (9.4) 2 (4.8) 12 (8.1) Partial response (PR) 18 (17.0) 11 (26.2) 29 (19.6) Minimal response (MR) 5 (4.7) 4 (9.5) 9 (6.1) Stable disease (SD) 46 (43.3) 22 (52.4) 68 (45.9) Progressive disease (PD) 18 (17.0) 0 18 (12.2) Not evaluable (NE) 6 (5.7) 1 (2.4) 7 (4.7) Overall response (sCR+CR+VGPR+PR) 31 (29.2) 15 (35.7) 46 (31.1) Disclosures Usmani: Celgene Corporation: Consultancy, Honoraria; Janssen: Research Funding; Onyx: Consultancy, Honoraria, Research Funding. Weiss:Janssen and Millennium: Consultancy; Janssen and Onclave: Research Funding. Bahlis:Johnson & Johnson: Research Funding; Amgen: Consultancy; Johnson & Johnson: Consultancy; Johnson & Johnson: Speakers Bureau; Celgene: Consultancy, Honoraria, Research Funding, Speakers Bureau. Lonial:Celgene: Consultancy, Research Funding; Janssen: Consultancy, Research Funding; Bristol-Myers Squibb: Consultancy, Research Funding; Millennium: Consultancy, Research Funding; Novartis: Consultancy, Research Funding; Onyx: Consultancy, Research Funding. Lokhorst:Genmab: Honoraria, Research Funding; Janssen: Honoraria, Research Funding; Amgen: Honoraria. Voorhees:Janssen, Celgene, GlaxoSmithKline,Onyx Pharmaceuticals and Oncopeptides: Consultancy, Research Funding; Array BioPharma, Celgene, GlaxoSmithKline, and Oncopeptides: Consultancy; Millennium/Takeda and Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees. Richardson:Bristol-Myers Squibb: Membership on an entity's Board of Directors or advisory committees; Celgene: Membership on an entity's Board of Directors or advisory committees; Novartis: Membership on an entity's Board of Directors or advisory committees; Millennium Takeda: Membership on an entity's Board of Directors or advisory committees; Johnson & Johnson: Membership on an entity's Board of Directors or advisory committees. Axel:Janssen: Employment. Feng:Janssen: Employment. Uhlar:Janssen: Employment. Wang:Janssen: Employment. Khan:Janssen: Employment. Ahmadi:Janssen: Employment. Nahi:Janssen: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Celgene: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau.

Key Points• NK cells decline as daratumumab exposure increases in a maximum effect type doseresponse relationship, with no efficacy and safety impact.• Remaining PBMC cell fractions maintained the ability to carry out daratumumab-mediated ex vivo ADCC.

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BackgroundPlasmablasts and plasma cells play a key role in many autoimmune diseases, such as rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE). This study was undertaken to evaluate the potential of targeting CD38 as a plasma cell/plasmablast depletion mechanism by daratumumab in the treatment of patients with RA and SLE.MethodsRNA-sequencing analysis of synovial biopsies from various stages of RA disease progression, flow cytometry analysis of peripheral blood mononuclear cells (PBMC) from patients with RA or SLE and healthy donors, immunohistochemistry assessment (IHC) of synovial biopsies from patients with early RA, and ex vivo immune cell depletion assays using daratumumab (an anti-CD38 monoclonal antibody) were used to assess CD38 as a therapeutic target.ResultsWe demonstrated that the plasma cell/plasmablast-related genes CD38, XBP1, IRF4, PRDM1, IGJ and TNFSF13B are significantly up-regulated in synovial biopsies from patients with arthralgia, undifferentiated arthritis (UA), early RA and established RA as compared to healthy controls and control patients with osteoarthritis. In addition, the highest CD38 expression was observed on plasma cells and plasmablasts compared to natural killer (NK) cells, classical dendritic cells (DCs), plasmacytoid DCs (pDCs) and T cells, in blood from healthy controls and patients with SLE and RA. Furthermore, IHC showed CD38 staining in the same region as CD3 and CD138 staining in synovial tissue biopsies from patients with early RA. Most importantly, our data show for the first time that daratumumab effectively depletes plasma cells/plasmablasts in PBMC from patients with SLE and RA in a dose-dependent manner ex vivo.ConclusionThese results indicate that CD38 may be a potential target for RA disease interception and daratumumab should be evaluated clinically for the treatment of both RA and SLE.Electronic supplementary materialThe online version of this article (10.1186/s13075-018-1578-z) contains supplementary material, which is available to authorized users.