Search

Quantified target bands from Figure 2

Dosing everolimus in combination with letrozole and seribantumab causes weight loss in mice

Brief descriptions of the supplementary figure data provided

Supplementary Figures S1-S6. Supplementary Fig. S1. The effect of cyclophosphamide on liposome delivery is dose dependent, requires a predose rather than a co-injection, and is not mediated by changes in blood clearance. Supplementary Fig. S2. Cyclophosphamide induces DNA-damage and tumor cell apoptosis. Supplementary Fig. S3. Effects of cyclophosphamide, ifosfamide, paclitaxel and eribulin on HER2-tPLD delivery, stromal cell density, total cell density, and interstitial space area. Supplementary Fig. S4. Pretreatment of tumors with cyclophosphamide significantly enhances nuclear delivery of doxorubicin following HER2-tPLD injection. Supplementary Fig. S5. Pretreatment of tumors with cyclophosphamide enhances the delivery of HER2-tPLD in multiple tumor models. Supplementary Fig. S6. The combination of a cyclophosphamide predose with HER2-tPLD results in synergistic anti-tumor activity.

Statistical analyses of tumor growth curves in mouse study 1 (Figure 3)

Given the bulky nature of nanotherapeutics relative to small molecules, it is hypothesized that effective tumor delivery and penetration are critical barriers to their clinical activity. HER2-targeted PEGylated liposomal doxorubicin (MM-302, HER2-tPLD) is an antibody–liposomal drug conjugate designed to deliver doxorubicin to HER2-overexpressing cancer cells while limiting uptake into nontarget cells. In this work, we demonstrate that the administration and appropriate dose sequencing of cyclophosphamide can improve subsequent MM-302 delivery and enhance antitumor activity in preclinical models without negatively affecting nontarget tissues, such as the heart and skin. We demonstrate that this effect is critically dependent on the timing of cyclophosphamide administration. Furthermore, the effect was found to be unique to cyclophosphamide and related analogues, and not shared by other agents, such as taxanes or eribulin, under the conditions examined. Analysis of the cyclophosphamide-treated tumors suggests that the mechanism for improved MM-302 delivery involves the induction of tumor cell apoptosis, reduction of overall tumor cell density, substantial lowering of interstitial fluid pressure, and increasing vascular perfusion. The novel dosing strategy for cyclophosphamide described herein is readily translatable to standard clinical regimens, represents a potentially significant advance in addressing the drug delivery challenge, and may have broad applicability for nanomedicines. This work formed the basis for clinical evaluation of cyclophosphamide for improving liposome deposition as part of an ongoing phase I clinical trial of MM-302 in HER2-positive metastatic breast cancer. Mol Cancer Ther; 14(9); 2060–71. ©2015 AACR.

Supplementary Tables S1-S3. Supplementary Table S1: Changes in tumor deposition in the control and cyclophosphamide-treated groups as measured by PET/CT. Supplementary Table S2: Effects of cyclophosphamide on HER2 expression, collagen type I deposition and vascular parameters in BT474-M3 tumors. Supplementary Table S3. Reagents for immunofluorescence on FFPE and frozen tumor sections

ERBB3 levels are significantly higher following co-treatment with letrozole and everolimus

Heregulin is expressed in MCF-7Ca and LTLT-Ca cells

Supplementary Materials and Methods. This file contains information on the reagents, methods for the evaluation of cell viability, preparation of liposomes and details on the image analysis.

Purpose: Therapeutic nanoparticles are designed to deliver their drug payloads through enhanced permeability and retention (EPR) in solid tumors. The extent of EPR and its variability in human tumors is highly debated and has been proposed as an explanation for variable responses to therapeutic nanoparticles in clinical studies.Experimental Design: We assessed the EPR effect in patients using a 64Cu-labeled nanoparticle, 64Cu-MM-302 (64Cu-labeled HER2-targeted PEGylated liposomal doxorubicin), and imaging by PET/CT. Nineteen patients with HER2-positive metastatic breast cancer underwent 2 to 3 PET/CT scans postadministration of 64Cu-MM-302 as part of a clinical trial of MM-302 plus trastuzumab with and without cyclophosphamide (NCT01304797).Results: Significant background uptake of 64Cu-MM-302 was observed in liver and spleen. Tumor accumulation of 64Cu-MM-302 at 24 to 48 hours varied 35-fold (0.52–18.5 %ID/kg), including deposition in bone and brain lesions, and was independent of systemic plasma exposure. Computational analysis quantified rates of deposition and washout, indicating peak liposome deposition at 24 to 48 hours. Patients were classified on the basis of 64Cu-MM-302 lesion deposition using a cut-off point that is comparable with a response threshold in preclinical studies. In a retrospective exploratory analysis of patient outcomes relating to drug levels in tumor lesions, high 64Cu-MM-302 deposition was associated with more favorable treatment outcomes (HR = 0.42).Conclusions: These findings provide important evidence and quantification of the EPR effect in human metastatic tumors and support imaging nanoparticle deposition in tumors as a potential means to identify patients well suited for treatment with therapeutic nanoparticles. Clin Cancer Res; 23(15); 4190–202. ©2017 AACR.

Fig. S1. MM-302 tumor deposition in preclinical xenografts as a function of HER2 expression. Fig. S2. Preclinical assessment of minimum 64Cu-MM-302 tumor delivery for anti-tumor activity. Fig. S3. Maximum intensity projection images of selected patients with average and rapid clearance of 64Cu-MM-302. Fig. S4. Stability of 64Cu-MM-302 in patients. Fig. S5. Hepatic tumor lesion with similar uptake as normal liver tissue. Fig. S6. Estimated parameter values (k1, k-1, VVF) for lesions from 3 patients who underwent 3 scans. Table S1. Model parameters for tracer kinetic modeling of 64Cu-MM-302 liposome transport into and out of tumors. Table S2. Patient Demographic (n=19). Table S3. Radiation Dosimetry of 64Cu-MM-302 (n=11).

Current therapeutic treatments improving the impaired transportation of oxygen in acute respiratory distress syndrome (ARDS) have been found to be relevant and beneficial for the therapeutic treatment of COVID-19 patients suffering from severe respiratory complications. Hence, we report the preclinical and the preliminary results of the Phase I/II clinical trial of LEAF-4L6715, a liposomal nanocarrier encapsulating the kosmotropic agent trans-crocetin (TC), which, once injected, enhance the oxygenation of vascular tissue and therefore has the potential to improve the clinical outcomes of ARDS and COVID-19 in severely impacted patients. We demonstrated that the liposomal formulation enabled to increase from 30 min to 48 h the reoxygenation properties of free TCs in vitro in endothelial cells, but also to improve the half-life of TC by 6-fold in healthy mice. Furthermore, we identified 25 mg/kg as the maximum tolerated dose in mice. This determined concentration led to the validation of the therapeutic efficacy of LEAF-4 L6715 in a sepsis mouse model. Finally, we report the preliminary outcomes of an open-label multicenter Phase I/II clinical trial (EudraCT 2020–001393-30; NCT04378920), which was aimed to define the appropriate schedule and dosage of LEAF-4L6715 and to confirm its tolerability profile and preliminary clinical activity in COVID-19 patients treated in intensive care unit., Graphical abstract Unlabelled Image

BACKGROUND: Overactivation of human epidermal growth factor receptor 3 (HER3) triggers multiple intracellular pathways resulting in tumor cell survival. This Phase 1 study assessed the safety, efficacy, and pharmacokinetics (PK) of seribantumab, a fully human anti-HER3 monoclonal antibody.METHODS: Adult patients with advanced or refractory solid tumors were treated in six dose cohorts of seribantumab: 3.2, 6, 10, 15, or 20 mg/kg weekly, or 40 mg/kg loading dose followed by 20 mg/kg weekly maintenance dose (40/20 mg/kg) using a modified 3+3 dose escalation strategy with cohort expansion. Primary objectives were identification of a recommended Phase 2 dose (RP2D) and determination of objective response rate. Secondary objectives were assessment of safety, dose-limiting toxicities, and PK.RESULTS: Forty-four patients (26 dose escalation; 18 dose expansion) were enrolled. Seribantumab monotherapy was well tolerated with most adverse events being transient and mild to moderate (grade 1 or 2) in severity; maximum tolerated dose was not reached. The highest dose, 40/20 mg/kg, was identified as RP2D. Best response was stable disease, achieved by 24% and 39% of patients during the dose escalation and expansion portions of the study, respectively. Seribantumab terminal half-life was ≈100 hours; steady state concentrations were reached after 3–4 weekly doses. CONCLUSIONS: Seribantumab monotherapy was well tolerated across all dose levels. Safety and PK data from this study support further seribantumab investigations in genomically defined populations. CLINICAL TRIAL REGISTRATION: NCT00734305.DATE OF REGISTRATION: August 12, 2008.

Background This phase 1 dose-escalation trial studied MM-302, a novel HER2-targeted PEGylated antibody–liposomal doxorubicin conjugate, in HER2-positive locally advanced/metastatic breast cancer. Methods Patients were enrolled in four cohorts: MM-302 monotherapy (8, 16, 30, 40, and 50 mg/m2 every 4 weeks [q4w]); MM-302 (30 or 40 mg/m2 q4w) plus trastuzumab (4 mg/kg q2w); MM-302 (30 mg/m2) plus trastuzumab (6 mg/kg) q3w; MM-302 (30 mg/m2) plus trastuzumab (6 mg/kg) and cyclophosphamide (450 mg/m2) q3w. Results Sixty-nine patients were treated. The most common adverse events (AEs) were fatigue and nausea. Grade 3/4 AEs of special interest included neutropenia, fatigue, mucosal inflammation, anemia, thrombocytopenia, febrile neutropenia, and palmar-plantar erythrodysesthesia. The MTD was not reached. With MM-302 ≥ 30 mg/m2, overall response rate (ORR) was 13% and median progression-free survival (mPFS) 7.4 months (95% CI: 3·5–10·9) in all arms. In 25 anthracycline-naïve patients, ORR was 28·0% and mPFS 10·9 months (95% CI: 1·8–15·3). Imaging with 64Cu-labeled MM-302 visualized tumor-drug penetrance in tumors throughout the body, including the brain. Conclusion MM-302 monotherapy, in combination with trastuzumab, or trastuzumab plus cyclophosphamide, was well tolerated and showed promising efficacy. The selected phase 2 MM-302 dose was 30 mg/m2 plus 6 mg/kg trastuzumab q3w.

This abstract was withdrawn by the authors.

Purpose Seribantumab is a fully human immunoglobulin G2 monoclonal antibody that binds to human epidermal growth factor receptor (HER) 3 (ErbB3), blocking heregulin (HRG) –mediated ErbB3 signaling and inducing ErbB3 receptor downregulation. This open-label randomized phase II study evaluated progression-free survival (PFS) with seribantumab in combination with once-per-week paclitaxel compared with paclitaxel alone in patients with platinum-resistant or -refractory ovarian cancer. A key secondary objective was to determine if any of five prespecified biomarkers predicted benefit from seribantumab. Patients and Methods Patients with platinum-resistant or -refractory epithelial ovarian, fallopian tube, or primary peritoneal cancer were randomly assigned at a ratio of two to one to receive seribantumab plus paclitaxel or paclitaxel alone. Patients underwent pretreatment core needle biopsy; archival tumor samples were also obtained to support biomarker analyses. Results A total of 223 patients were randomly assigned (seribantumab plus paclitaxel, n = 140; paclitaxel alone, n = 83). Median PFS in the unselected intent-to-treat population was 3.75 months with seribantumab plus paclitaxel compared with 3.68 months with paclitaxel alone (hazard ratio [HR], 1.027; 95% CI, 0.741 to 1.425; P = .864). Among patients whose tumors had detectable HRG mRNA and low HER2 (n = 57 [38%] of 151 with available biomarker data), increased treatment benefit was observed in those receiving seribantumab plus paclitaxel compared with paclitaxel alone (PFS HR, 0.37; 95% CI, 0.18 to 0.76; P = .007). The HR in patients not meeting these criteria was 1.80 (95% CI, 1.08 to 2.98; P = .023). Conclusion The addition of seribantumab to paclitaxel did not result in improved PFS in unselected patients. Exploratory analyses suggest that detectable HRG and low HER2, biomarkers that link directly to the mechanism of action of seribantumab, identified patients who might benefit from this combination. Future clinical trials are needed to validate this finding and should preselect for HRG expression and focus on cancers with low HER2 levels.

11042 Background: While the American Council on Graduate Medical Education (ACGME) set up a Planning Committee for Diversity in GME in 2018, no formalized milestones or training mandates have been announced. The nation-wide protests for racial justice following the senseless killings of Breonna Taylor, Ahmaud Arbery and George Floyd further brought to the forefront the need for immediate action to address widespread inequities across graduate medical education, our healthcare system and society as a whole. Therefore, the Johns Hopkins Hematology/Medical Oncology Fellowship Program focused on creating an anti-racism curriculum to foster dialogue on systemic racism and discrimination, grounded in the institutional and geographic context of our training program. Methods: Using the Kern six step curriculum development method, we created a comprehensive anti-racism initiative, which included virtual townhalls with Black alumni of the fellowship, book clubs, readings, and lectures. We sought to deepen the fellowship’s awareness of the impact of racism and inequity upon trainees, underrepresented minority oncologists and hematologists, and patients in order to develop initiatives to confront them productively. Trainees received a survey 6 months after the start of the curriculum to assess the impact of the initiatives upon trainees, and inform iterative changes to the curriculum. Results: 25 of 34 fellows across all post-graduate years (PGY) completed the survey. Fellows agreed that the curriculum was helpful (68%) and encouraging (60%). Collectively, fellows reported that the curriculum increased their awareness of instances of racism in medicine, caused them to think about next steps that the fellowship could take to address racism, and enabled them to identify available resources for support and further education. Respondents selected community engagement and recruitment of diverse fellowship classes as the most pressing priorities for the program. Conclusions: Social justice and anti-racism education belong in the formalized training of our hematology/medical oncology fellows. To this end, our ongoing curricular expansion is focusing on anti-racism training, diverse recruitment and youth mentorship. Collectively, a comprehensive yet program-specific approach facilitates opportunities for learning, engagement and development of the skills necessary to engage in this life-long work for ourselves, our communities and our patients.

3524 Background: The activity of pemetrexed is highly dependent on the intracellular enzyme folypolyglutamate synthase (FPGS) which adds glutamates to pemetrexed and yields very potent pemetrexed polyglutamates. Pemetrexed pentaglutamate (tetraglutamated pemetrexed) is 80-fold more potent than pemetrexed in inhibiting thymidylate synthase. Yet it is a poor drug candidate because it cannot readily cross the negatively charged cell membrane due to its own negative charge. We are developing LEAF-1401, a novel nanoliposomal encapsulation of gamma L-pentaglutamated pemetrexed. Because liposomes can readily be taken up by tumor cells, for its anti-tumor effect, LEAF-1401 can directly deliver pentaglutamated pemetrexed into tumor cells, bypassing the need for transmembrane folate carriers and FPGS which are both downregulated in resistant tumors. Methods: To measure drug levels in tumor, blood and various tissues (biodistribution), in vivo testing of LEAF-1401 and pemetrexed was conducted in a CT-26 murine colorectal carcinoma xenograft model. Animals were treated with a single dose of either LEAF-1401 (80mg/kg; equivalent to 32 mg/kg pemetrexed) or pemetrexed (118mg/kg). Tumor growth inhibition and clinical assessments were conducted. Animals were sacrificed: 5 mice per timepoint in each group and tumor, blood, liver, spleen and other tissues were harvested. Pentaglutamated pemetrexed levels were quantitatively analyzed by LC/MS/MS. Results: Compared to pemetrexed, LEAF-1401 treatment resulted in a 19-fold increase in exposure levels of pentaglutamated pemetrexed in the tumor and significant tumor growth inhibition. Plasma levels of pentaglutamated pemetrexed were high with LEAF-1401, but undetectable with pemetrexed. Like other liposomes, LEAF-1401 also resulted in accumulation of pentaglutamated pemetrexed in the liver and spleen (See Table below). Treatment appeared to be generally well tolerated. Conclusions: LEAF-1401, given at approximately a quarter of the equivalent pemetrexed dose, resulted in a 19-fold increase in pentaglutamate pemetrexed in tumor tissue compared to regular pemetrexed. LEAF-1401 represents a promising new class of novel nanoliposomal antifolates, that enhance the intratumoral delivery of potent polyglutamate antifolates, and improve antitumor activity while retaining an acceptable safety profile. [Table: see text]

Given the bulky nature of nanotherapeutics relative to small molecules, it is hypothesized that effective tumor delivery and penetration are critical barriers to their clinical activity. HER2-targeted PEGylated liposomal doxorubicin (MM-302, HER2-tPLD) is an antibody–liposomal drug conjugate designed to deliver doxorubicin to HER2-overexpressing cancer cells while limiting uptake into nontarget cells. In this work, we demonstrate that the administration and appropriate dose sequencing of cyclophosphamide can improve subsequent MM-302 delivery and enhance antitumor activity in preclinical models without negatively affecting nontarget tissues, such as the heart and skin. We demonstrate that this effect is critically dependent on the timing of cyclophosphamide administration. Furthermore, the effect was found to be unique to cyclophosphamide and related analogues, and not shared by other agents, such as taxanes or eribulin, under the conditions examined. Analysis of the cyclophosphamide-treated tumors suggests that the mechanism for improved MM-302 delivery involves the induction of tumor cell apoptosis, reduction of overall tumor cell density, substantial lowering of interstitial fluid pressure, and increasing vascular perfusion. The novel dosing strategy for cyclophosphamide described herein is readily translatable to standard clinical regimens, represents a potentially significant advance in addressing the drug delivery challenge, and may have broad applicability for nanomedicines. This work formed the basis for clinical evaluation of cyclophosphamide for improving liposome deposition as part of an ongoing phase I clinical trial of MM-302 in HER2-positive metastatic breast cancer. Mol Cancer Ther; 14(9); 2060–71. ©2015 AACR.

Background: Liposomal encapsulation of doxorubicin has addressed the cardiotoxicity of free doxorubicin, but has not achieved an improvement in anti-tumor activity in metastatic breast cancer. MM-302 is a HER2-targeted liposomal doxorubicin, specifically designed to target tumor cells overexpressing HER2 and minimize uptake into normal cells such as cardiomyocytes, which express low levels of HER2. MM-302 and MM-302 plus trastuzumab are being studied in patients as part of an ongoing Phase 1 clinical trial. Published reports indicate that deposition into solid tumors is a rate-limiting step in liposome-mediated delivery of drug to tumor cells. In order to understand drug deposition into solid tumors, we have radiolabeled MM-302 with 64Cu for imaging by PET/CT. Further, preclinical work has demonstrated that pretreatment with cyclophosphamide has the ability to improve liposomal drug delivery by making the tumor microenvironment permissive for deposition and retention of liposomes. This Phase 1 study evaluates the delivery of 64Cu-MM-302 to solid tumors and the ability of cyclophosphamide pretreatment to increase delivery of 64Cu-MM-302 to tumors. Methods: Patients aged ≥ 18 years with histologically confirmed HER2-positive advanced breast cancer that has progressed or recurred on standard therapy or for which no standard therapy exists, who have adequate performance status, bone marrow reserve and organ function, were eligible for the study. Patients received 30 mg/m2 of MM-302 plus 6 mg/kg trastuzumab, q3w and 400 MBq (10.8 mCi; 3-5 mg/m2, doxorubicin basis) of 64Cu-MM-302 (cycle 1 only) with or without pretreatment of 450 mg/m2 cyclophosphamide. Patients underwent PET/CT on the day of administration and on day 2, day 3 or both. The primary goal of this analysis was to study delivery of 64Cu-MM-302 and the effect of cyclophosphamide pretreatment. Other endpoints being studied include safety, dosimetry, and treatment response. Results: Combination of MM-302 with cyclophosphamide was well tolerated and no issues were reported related to 64Cu-MM-302 administration or imaging. Uptake of 64Cu-MM-302 in tumor lesions increased over time with significant deposition at 24 and 48 h while activity in the blood decreased over time. Median lesion deposition of 64Cu-MM-302 (as % i.d./kg) in the patients with cyclophosphamide pretreatment was higher than in those without pretreatment: 6.0 (n=5 patients/20 lesions) vs. 4.4 (n=7 patients/36 lesions) at 24 h and 7.6 (n=4 patients/16 lesions) vs. 4.0 (n=4 patients/17 lesions) at 48 h. Conclusions: PET/CT imaged 64Cu-MM-302 deposition into diverse tumor lesions, including liver, brain and bone metastases. Our preliminary data thus far suggest that cyclophosphamide pretreatment increases delivery of 64Cu-MM-302 to patient tumors, as predicted by preclinical models. Correlation between 64Cu-MM-302 tumor deposition and lesion/patient response is currently being investigated. Citation Format: Kathy Miller, Patricia M LoRusso, Pamela Munster, Ian Krop, Cynthia Ma, Helen Lee, Joe Reynolds, Karen Campbell, Victor Moyo, Bart Hendriks, Thomas Wickham, Barry A Siegel, Anthony F Shields. Effect of pre-treatment with cyclophosphamide on MM-302 (HER2-targeted liposomal doxorubicin) deposition in HER2-positive metastatic breast cancer patients assessed by 64Cu-MM-302 PET/CT [abstract]. In: Proceedings of the Thirty-Seventh Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2014 Dec 9-13; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2015;75(9 Suppl):Abstract nr P4-15-04.

The ErbB family of receptor tyrosine kinases comprises four members: epidermal growth factor receptor (EGFR/ErbB1), human EGFR 2 (HER2/ErbB2), ErbB3/HER3, and ErbB4/HER4. The first two members of this family, EGFR and HER2, have been implicated in tumorigenesis and cancer progression for several decades, and numerous drugs have now been approved that target these two proteins. Less attention, however, has been paid to the role of this family in mediating cancer cell survival and drug tolerance. To better understand the complex signal transduction network triggered by the ErbB receptor family, we built a computational model that quantitatively captures the dynamics of ErbB signaling. Sensitivity analysis identified ErbB3 as the most critical activator of phosphoinositide 3-kinase (PI3K) and Akt signaling, a key pro-survival pathway in cancer cells. Based on this insight, we designed a fully human monoclonal antibody, seribantumab (MM-121), that binds to ErbB3 and blocks signaling induced by the extracellular growth factors heregulin (HRG) and betacellulin (BTC). In this article, we present some of the key preclinical simulations and experimental data that formed the scientific foundation for three Phase 2 clinical trials in metastatic cancer. These trials were designed to determine if patients with advanced malignancies would derive benefit from the addition of seribantumab to standard-of-care drugs in platinum-resistant/refractory ovarian cancer, hormone receptor-positive HER2-negative breast cancer, and EGFR wild-type non-small cell lung cancer (NSCLC). From preclinical studies we learned that basal levels of ErbB3 phosphorylation correlate with response to seribantumab monotherapy in mouse xenograft models. As ErbB3 is rapidly dephosphorylated and hence difficult to measure clinically, we used the computational model to identify a set of five surrogate biomarkers that most directly affect the levels of p-ErbB3: HRG, BTC, EGFR, HER2, and ErbB3. Preclinically, the combined information from these five markers was sufficient to accurately predict which xenograft models would respond to seribantumab, and the single-most accurate predictor was HRG. When tested clinically in ovarian, breast and lung cancer, HRG mRNA expression was found to be both potentially prognostic of insensitivity to standard therapy and potentially predictive of benefit from the addition of seribantumab to standard of care therapy in all three indications. In addition, it was found that seribantumab was most active in cancers with low levels of HER2, consistent with preclinical predictions. Overall, our clinical studies and studies of others suggest that HRG expression defines a drug-tolerant cancer cell phenotype that persists in most solid tumor indications and may contribute to rapid clinical progression. To our knowledge, this is the first example of a drug designed and clinically tested using the principles of Systems Biology.

e14515 Background: Polyglutamation of antifolates by folylpolyglutamate synthase (FPGS) greatly enhances their activity, e.g. pentaglutamated pemetrexed is 80-fold more potent at inhibiting thymidylate synthase than pemetrexed. Polyglutamated antifolates however, do not readily cross the cell membrane, due to high negative charge and molecular mass. The resulting poor intracellular bioavailability greatly limits their therapeutic potential. Gamma glutamyl hydrolase (GGH) enzyme removes the glutamate residues from polyglutamates, which then are subject to efflux pumps. Resistance to pemetrexed has been linked to downregulation of both FPGS and folate transporters and upregulation of both GGH and the efflux pumps. We have been developing a novel class of nanoliposomal polyglutamated-antifolates including: LEAF-1401; nanoliposomal gamma-L pentaglutamated antifolate LEAF-1701; nanoliposomal alpha-L pentaglutamated antifolate These were designed to address key challenges of currently used antifolates namely: Bypassing the need for intracellular endogenous FPGS Direct delivery of the much more active polyglutamates through nanoliposome technology Minimizing toxicity to normal cells Mitigating against key antifolate resistance mechanisms such as downregulation of FPGS and folate transporters, and upregulation of GGH and efflux pumps Methods: In vitro testing in cell lines and in vivo testing in mice were performed using LEAF-1701 and LEAF-1401 in various tumor types. Results: Compared to pemetrexed: In vitro, LEAF-1701 and LEAF-1401 were more potent, in various cell lines while sparing normal neutrophils, colon and liver cells. In vivo, in H292 lung cancer xenografts, treatment with LEAF-1701 improved survival to 59 days vs 39 days for pemetrexed. In A549 lung cancer mouse orthotopic models, treatment with LEAF-1401 reduced metastatic tumor burden and prevented new metastases. In vivo, in mice doses of up to 80 mg/kg IV weekly were tolerated with little impact on blood counts and chemistry. Conclusions: LEAF-1701 and LEAF-1401 are innovative new chemical entities with promising preclinical activity and improved safety profiles and are now advancing to the clinic.

Background: MM-302 is a novel antibody drug conjugate (ADC) combining PEGylated liposomal doxorubicin with anti-HER2 scFvs. MM-302 was designed to overcome the limitations associated with using anthracyclines in the treatment of HER2-positive breast cancer. Anthracyclines have been an effective backbone of breast cancer therapies for decades. However, cardiotoxicity issues associated with free anthracyclines have limited their effective use. While liposomal doxorubicin formulations have succeeded in reducing cardiotoxicity, they have failed to demonstrate clear-cut efficacy advantages. MM-302 specifically targets tumor cells overexpressing HER2 with minimal uptake into normal cells such as cardiomyocytes which express low levels of HER2. This Phase 1 study evaluates the safety of MM-302 in patients with HER2+ advanced breast cancer. Methods: Patients aged ≥ 18 years with histologically confirmed HER2+ advanced breast cancer that have progressed or recurred on standard therapy or for which no standard therapy exists having measurable disease, adequate performance status, bone marrow reserve and organ function, were eligible for the study. A post-treatment biopsy was required. A 3 + 3 dose escalation design (8, 16, 30, 40 and 50 mg/m2 administered i.v. q4w) is used to identify a Phase 2 dose followed by expansion arms at 40 and 50 mg/m2 for a preliminary indication of activity. Secondary endpoints included determination of dose-limiting toxicity, adverse event(s), and PK of MM-302, as well as overall response and clinical benefit rates of MM-302. Results: We report data from MM-302 dose levels (30, 40 and 50 mg/m2 as monotherapy) that are expected to be therapeutically relevant. Eight patients dosed at presumed sub-therapeutic dose levels of 8 and 16 mg/m2 were excluded from the efficacy analysis. Patients had received a median of 9.5 prior agents (range 3-19) in all settings. All patients had been treated with trastuzumab, 96% with prior taxanes, 67% lapatinib, 54% anthracyclines and 33% T-DM1. At the time of this analysis (n = 27), overall response rate was 17% (4 out of 24 evaluable patients) and the estimated median Progression Free Survival (PFS) was 5.7 months, with six patients still receiving treatment. Eight patients (30%) had a PFS of greater than 6.0 months. Neutropenia was the most common treatment-related grade 3/4 toxicity and occurred in 15% of patients. The most common adverse events include fatigue, nausea, vomiting, and decreased appetite. Constipation, stomatitis, headache and rash were also observed in greater than 20% of patients. No patients discontinued treatment for toxicity. There was no protocol defined cardiotoxicity observed across all dose cohorts and five patients have had cumulative anthracycline exposure exceeding 550 mg/m2 without a reduction in left ventricular ejection fraction. Conclusion: Overall MM-302 appears to be well tolerated with promising activity in this ongoing trial. Further development is continuing combining MM-302 with trastuzumab and/or cyclophosphamide. In addition, we are evaluating the use of PET imaging to correlate liposomal tumor deposition as an additional potential patient preselection strategy. Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P4-12-29.

Background: Anthracyclines have been an effective backbone of breast cancer therapies for decades. However, cardiotoxicity issues associated with free anthracyclines have limited their effective use in the clinic and ledto the exploration of anthracycline-free regimens, particularly with HER2- positive cancers that require treatment with another cardiotoxic agent, trastuzumab. While liposomal doxorubicin formulations have succeeded in reducing cardiotoxicity, they have failed to demonstrate clearcut efficacy advantages and can involve other toxicities. To address the safety and efficacy limitations of currently available anthracyclines, we have designed a new liposomal formulation, MM-302, that targets doxorubicin to HER2- overexpressing tumor cells. Antibody fragments that bind to HER2 without blocking HER2-mediated signaling are coupled to the outer surface of pegylated liposomal doxorubicin. MM-302 specifically binds and enters tumor cells overexpressing HER2 with minimal uptake into normal cells such as cardiomyocytes which express low levels of HER2. Materials and methods: MM-302, untargeted pegylated liposomal doxorubicin (PLD), and free doxorubicin were compared for their uptake into target and nontarget cells, pharmacokinetics, biodistribution, tumor microdistribution using FACS and confocal microscopy, and anti-tumor activity in BT-474 and NCI-N87 xenograft models. Results: Cellular uptake studies in tumor cell lines expressing various levels of HER2 demonstrate that MM-302 delivers significantly higher doxorubicin levels to HER2 over-expressing tumor cells compared to PLD as well as similar or higher levels than highly permeable free doxorubicin. However, in human cardiomyocytes, while free doxorubicin was again taken up at high levels, doxorubicin uptake was dramatically lower with both MM-302 and PLD. Pharmacokinetic studies in mice demonstrate that MM-302 has a similar half life, clearance, and organ distribution compared to PLD. In HER2-overexpressing BT-474 breast and NCI-N87 gastric tumor xenografts, MM-302 exhibits superior anti-tumor activity to both free anthracyclines and PLD. Tumor microdistribution studies further suggest that differences in the localization of doxorubicin in the tumor may be responsible for the enhanced activity of MM-302 compared to free doxorubicin and PLD. Discussion: These preclinical data suggest that MM-302 may provide in clinical practice a new opportunity to specifically deliver an anthracycline to HER2-overexpressing tumors with a potentially cleaner safety profile and improved efficacy over currently available free or liposomal doxorubicin. Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr P3-14-09.

Although HLA-linked hemochromatosis greatly increases the risk for hepatocellular carcinoma in people of European ancestry, iron overload in Africa is not thought to be etiologically related to this malignancy. To determine if African iron overload may be associated with hepatocellular carcinoma, we reviewed 320 consecutive diagnostic liver biopsies processed at the University of Zimbabwe from 1992 to 1994 and we selected for analysis 215 biopsies from adults that were suitable for the histological assessment of hepatocellular iron. Subjects were stratified according to hepatocellular iron grades of 0-2+ (normal levels to mild siderosis; n = 183) and grades of 3+ and 4+ (distinctly elevated levels consistent with iron overload; n = 32). Thirty-six subjects had hepatocellular carcinoma. Logistic regression modeling revealed a significant association between iron overload and hepatocellular carcinoma after adjustment for age, sex and and the presence of portal fibrosis or cirrhosis (p = 0.041). The odds of hepatocellular carcinoma in subjects with iron overload was 3.1 (95% confidence interval of 1.05-9.4) times that of subjects without iron overload. While we could not test for exposure to viral hepatitis or to aflatoxins in this study, our findings suggest that iron overload may be a risk factor for hepatocellular carcinoma in Africa.

In the setting of high dietary, several studies have provided evidence for a strong effect of both high dietary iron and an unidentified genetic locus on iron stores in Africans. To investigate whether these effects are discernible in the setting of low dietary iron, serum ferritin concentrations were measured in 194 Zimbabwean men >30 years of age and 299 postmenopausal women who consumed a non-iron-fortified diet and who did not drink iron-rich traditional beer or other alcoholic beverages. Comparisons were made with non-alcohol drinking African-Americans studied in the third National Health and Nutritional Examination Survey (NHANES III) who consume an iron-fortified diet. As stratified by age and sex, serum ferritin concentrations were significantly lower in the 493 Zimbabweans studied than in 1,380 comparable African-Americans (P < 0.0005). Nevertheless, nine Zimbabwean subjects (1.8% of all cases) had modestly elevated serum ferritin concentrations not associated with evidence of inflammation or hepatic dysfunction. These data suggest that mild serum ferritin concentration elevations may occur among Zimbabweans not exposed to high dietary iron and that iron fortification of the diet may have substantial effects on serum ferritin concentration.

BACKGROUND: Epoetin a (EPO) continues to be the initial treatment of choice for most anemic patients with myelodysplastic syndromes (MDS). Over the years, different therapeutic strategies have been adopted to optimize the clinical benefits of EPO in this setting. METHODS: In the current meta-analysis of published literature, erythroid response (ER) rates with EPO as a single agent versus its combination with granulocyte–colony-stimulating factor (G-CSF) or granulocyte-macrophage–colony-stimulating factor (GM-CSF) were compared. RESULTS: The assessment indicated that the ER rates were comparable between the 2 EPO-based therapeutic strategies. Furthermore, EPO monotherapy at a higher dose of 60,000 to 80,000 U weekly produced significantly higher ER rates (64.5%) compared with the standard oncology dose of 30,000 to 40,000 U weekly either as a single agent (49%; P < .001) or in combination with G-CSF/GM-CSF (50.6% P ¼ .007). In addition, when transfusion-dependent patients were assessed separately, both EPO monotherapy and its combination with G-CSF/GM-CSF produced comparable and appreciable levels of transfusion independence (28.8% and 24.8%, respectively). CONCLUSIONS: In the current meta-analysis, higher doses of EPO demonstrated better ER rates compared with EPO at standard doses alone or in combination with G-CSF/GM-CSF. Furthermore, the authors concluded that prospective clinical studies are warranted to evaluate the use of higher doses of EPO in anemic patients with MDS. Cancer 2009;115:706–15. V C 2009 American Cancer Society.

Summary Background Nanoliposomal irinotecan showed activity in a phase 2 study in patients with metastatic pancreatic ductal adenocarcinoma previously treated with gemcitabine-based therapies. We assessed the effect of nanoliposomal irinotecan alone or combined with fluorouracil and folinic acid in a phase 3 trial in this population. Methods We did a global, phase 3, randomised, open-label trial at 76 sites in 14 countries. Eligible patients with metastatic pancreatic ductal adenocarcinoma previously treated with gemcitabine-based therapy were randomly assigned (1:1) using an interactive web response system at a central location to receive either nanoliposomal irinotecan monotherapy (120 mg/m 2 every 3 weeks, equivalent to 100 mg/m 2 of irinotecan base) or fluorouracil and folinic acid. A third arm consisting of nanoliposomal irinotecan (80 mg/m 2 , equivalent to 70 mg/m 2 of irinotecan base) with fluorouracil and folinic acid every 2 weeks was added later (1:1:1), in a protocol amendment. Randomisation was stratified by baseline albumin, Karnofsky performance status, and ethnic origin. Treatment was continued until disease progression or intolerable toxic effects. The primary endpoint was overall survival, assessed in the intention-to-treat population. The primary analysis was planned after 305 events. Safety was assessed in all patients who had received study drug. This trial is registered at ClinicalTrials.gov, number NCT01494506. Findings Between Jan 11, 2012, and Sept 11, 2013, 417 patients were randomly assigned either nanoliposomal irinotecan plus fluorouracil and folinic acid (n=117), nanoliposomal irinotecan monotherapy (n=151), or fluorouracil and folinic acid (n=149). After 313 events, median overall survival in patients assigned nanoliposomal irinotecan plus fluorouracil and folinic acid was 6·1 months (95% CI 4·8–8·9) vs 4·2 months (3·3–5·3) with fluorouracil and folinic acid (hazard ratio 0·67, 95% CI 0·49–0·92; p=0·012). Median overall survival did not differ between patients assigned nanoliposomal irinotecan monotherapy and those allocated fluorouracil and folinic acid (4·9 months [4·2–5·6] vs 4·2 months [3·6–4·9]; 0·99, 0·77–1·28; p=0·94). The grade 3 or 4 adverse events that occurred most frequently in the 117 patients assigned nanoliposomal irinotecan plus fluorouracil and folinic acid were neutropenia (32 [27%]), diarrhoea (15 [13%]), vomiting (13 [11%]), and fatigue (16 [14%]). Interpretation Nanoliposomal irinotecan in combination with fluorouracil and folinic acid extends survival with a manageable safety profile in patients with metastatic pancreatic ductal adenocarcinoma who previously received gemcitabine-based therapy. This agent represents a new treatment option for this population. Funding Merrimack Pharmaceuticals.

Heregulin-driven ERBB3 signaling has been implicated as a mechanism of resistance to cytotoxic and antiendocrine therapies in preclinical breast cancer models. In this study, we evaluated the effects of seribantumab (MM-121), a heregulin-blocking anti-ERBB3 monoclonal antibody, alone and in combination with the aromatase inhibitor letrozole, on cell signaling and tumor growth in a preclinical model of postmenopausal estrogen receptor–positive (ER+) breast cancer. In vitro, heregulin treatment induced estrogen receptor phosphorylation in MCF-7Ca cells, and long-term letrozole-treated (LTLT-Ca) cells had increased expression and activation levels of EGFR, HER2, and ERBB3. Treatment with seribantumab, but not letrozole, inhibited basal and heregulin-mediated ERBB receptor phosphorylation and downstream effector activation in letrozole-sensitive (MCF-7Ca) and -refractory (LTLT-Ca) cells. Notably, in MCF-7Ca–derived xenograft tumors, cotreatment with seribantumab and letrozole had increased antitumor activity compared with letrozole alone, which was accompanied by downregulated PI3K/MTOR signaling both prior to and after the development of resistance to letrozole. Moreover, the addition of an MTOR inhibitor to this treatment regimen did not improve antitumor activity and was not well tolerated. Our results demonstrate that heregulin-driven ERBB3 signaling mediates resistance to letrozole in a preclinical model of ER+ breast cancer, suggesting that heregulin-expressing ER+ breast cancer patients may benefit from the addition of seribantumab to antiendocrine therapy. Mol Cancer Ther; 14(11); 2642–52. ©2015 AACR.

Background: Genetic variants of human transferrin (TF) have been described, but little is known about their functional differences. We studied iron status according to TF phenotype in a healthy Zimbabwean population and in subjects at risk of African iron overload. Methods: The study population consisted of 483 nondrinkers, 31 drinking spouse pairs, and 5 family pedigrees (n = 88) with index cases of iron overload. TF phenotypes were determined using starch gel electrophoresis. To evaluate iron status, serum iron, total iron-binding capacity (TIBC), ferritin, and soluble TF receptors were measured, and the percentage of saturation and the serum iron:TF ratio were calculated. The binding of the TF variants was studied by equilibrium dialysis. Results: The reference population was characterized by a high TF D allele frequency (0.050) and a complete absence of homozygous TF DD individuals. Similar allele frequencies were observed in subjects at risk of African iron overload. In the reference population, male TF CD heterozygotes had significantly lower (P Conclusions: The present data demonstrate a functional difference between TF phenotypes in blacks.

To identify a marker associated with poor outcome in severe malaria that requires no technology, the relationship between the presence of pallor and mortality was reviewed retrospectively in 291 Zambian children with cerebral malaria. The mean (S.D.) haemoglobin concentration among the 222 children assessed as having pallor on admission was significantly lower than that among the 69 children not considered to have pallor [6.0 (1.9) v. 9.2 (1.6) g/dl; P < 0.0005]. Thirty-nine (17.6%) of the children presenting with pallor died, compared with only five (7.2%) of those without pallor (P = 0.036). The adjusted odds of death in children with pallor on admission was 2.8 times higher than that in children without pallor (95% confidence interval = 1.03-7.7; P = 0.044). The clinical observation of pallor may therefore identify children with low haemoglobin concentrations and a high risk of mortality. Whether mothers and village health workers can be taught to recognize pallor in a child with malaria and then to seek early medical attention will need to be determined in further studies.

To test the hypothesis that the quantities of circulating transferrin receptors are reduced in iron overload, we studied serum transferrin receptors and indirect measures of iron status in 150 subjects from rural Zimbabwe. We found significant inverse correlations between serum concentrations of transferrin receptors and ferritin, the ratio of ferritin to aspartate aminotransferase, and transferrin saturation (r ≥0.44; P 300 μg/L and transferrin saturation >60%) was 1.55 ± 0.61 mg/L, significantly lower than the 2.50 ± 0.62 mg/L in 75 subjects with normal iron stores (ferritin 20–300 μg/L and transferrin saturation 15–55%; P

The presenting features of 195 children with cerebral malaria were analysed to determine which correlated with severity of coma and anaemia. The children, who came from a single community in southern Zambia, were enrolled in an ongoing blinded drug trial in 1992 and 1993. Children with deep coma (scoring 0-2) had significantly longer duration of coma before presentation (P = 0.019) and were more likely to have been treated with chloroquine (P = 0.022) than children with light coma (scoring 3 or 4 on the Blantyre coma scale). Children with severe anaemia (haematocrit18%) were younger (P = 0.005), had been febrile longer (P = 0.005), had splenomegaly (P0.005) and hypoglycaemia (P0.008) more often and were more likely to have been treated with chloroquine (P0.005) than those without severe anaemia. The counts of asexual parasites in the peripheral blood were not significantly correlated with depth of coma or severity of anaemia. The observed widespread and uncontrolled use of chloroquine has probably led to the development of resistant malaria and of many severe complications despite early consultation. While early treatment of febrile illnesses in young children and immediate medical attention for altered consciousness must be emphasized in the community approach to severe malaria, our data indicate that effective public health measures will be difficult to develop in the face of a high prevalence of chloroquine resistance.

Introduction: MM-302 is an antibody-liposomal drug conjugate designed specifically to target doxorubicin to HER2-overexpressing tumor cells. MM-302 is currently being evaluated in a Phase II trial in HER2 positive metastatic breast cancer (NCT02213744). HER2-positive breast cancer accounts for about 15-20% of breast cancer cases and is defined as IHC 3+ or 2+ and HER2 FISH amplified. A substantial percentage (∼30%) of breast cancer patients show positive HER2 IHC (1+/2+) without HER2 gene amplification (“HER2 intermediate”). This population is not eligible for treatment with currently approved HER2-targeted therapies. The purpose of this study is to investigate the in vitro and in vivo delivery/activity of MM-302 in the HER2 intermediate population. Methods: In vitro binding and viability studies were performed with MM-302, PEGylated liposomal doxorubicin (PLD) and T-DM1 with a panel of cell lines representing a range of HER2 expression. HER2-mediated cellular delivery of MM-302 was investigated in vivo in different HER2 expressing tumor models using a novel PEG immunofluorescent assay herein described. Frozen tumor tissues were stained for PEG, HER2 and cytokeratin, side-by-side with two cell standard arrays: A PEG array, obtained by cell incubation with increasing concentrations of MM-302, and a HER2 array, built with a panel of cell lines at different HER2 expression (from ∼50,000 to over 1,000,000 HER2). Image analysis and subsequent regression of the PEG and HER2 fluorescent intensities from the respective standards allowed for the quantification of the number of liposomes in individual tumor cells at distinct HER2 receptor numbers. Tumor cell apoptosis following MM-302 cellular delivery was measured by immunofluorescence followed by image analysis. Results: MM-302 efficiently bound to, and induced, tumor cell death across a panel of cell lines, with no significant distinction between cell lines expressing 300-400,000 HER2 or above 1,000,000 HER2 (IHC 3+). Conversely, T-DM1, used as control, significantly bound to and induced cell death only to cells above 1,000,000 HER2 (IHC 3+). In vivo evaluation of HER2-mediated cellular delivery via PEG immunofluorescent staining showed that MM-302 can be equally efficiently internalized in tumor cells above 1,000,000 HER2 (IHC 3+) and in the HER2 intermediate expression range. Preliminary analysis on post-treatment patient biopsies collected during a MM-302 Phase I study (NCT01304797) support clinical translation of these preclinical observations. Conclusions: Treatment with MM-302 results in efficient HER2 binding and liposome cellular delivery across a panel of HER2 models that extend beyond the traditional HER2 positive definition. This study suggests that MM-302 may be a promising candidate for the treatment of patients with intermediate HER2 expression who represent a significant unmet medical need. Citation Format: Elena Geretti, Christopher Espelin, Bambang Adiwijaya, Nancy Dumont, Silvia Coma, Zachary Koncki, Minh Pham, Gabriela Garcia, Troy Bloom, Victoria Rimkunas, Joe Reynolds, Karen Campbell, Victor Moyo, Istvan Molnar, Patricia LoRusso, Ian Krop, Kathy Miller, Cynthia Ma, Pamela Munster, Thomas Wickham. HER2-targeted PEGylated liposomal doxorubicin (MM-302) efficiently targets the HER2 intermediate cell population in vitro and in vivo. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr LB-061.

Background: Nal-IRI (MM-398, nanoliposomal irinotecan) is designed for extended circulation relative to free irinotecan and to exploit leaky tumor vasculature for enhanced drug delivery to tumors. Tumor deposition of nal-IRI and subsequent conversion to SN-38 in both neoplastic cells and tumor associated macrophages (TAM) may positively correlate with response to therapy. In phase I studies of nal-IRI, activity has been shown in metastatic breast cancer (MBC), pancreatic and colorectal cancer. Ferumoxytol (FMX) is an iron-oxide superparamagnetic nanoparticle that has been used off-label for its MRI contrast properties. FMX has long-circulating pharmacokinetics and is taken up by TAMs with similar distribution patterns to nal-IRI in preclinical models. A single site pilot study established the feasibility of performing quantitative FMX MRI. Thirteen patients with advanced cancer (3 with ER/PR+ MBC) were imaged with FMX MRI and treated with nal-IRI. Median tumor lesion FMX uptake in the pilot study was 32.6 and 34.5 μg/mL at 1 h and 24 h, respectively. Lesions with FMX uptake above the median were associated with greater reductions in tumor size following treatment with nal-IRI as determined by CT lesion measurements. The relationship between FMX levels in tumor lesions and nal-IRI activity may serve as a potential biomarker for nal-IRI deposition and response in solid tumors. This study has been expanded to include additional MBC patients to further evaluate the technical feasibility of FMX MRI at multiple study sites, and to evaluate activity of nal-IRI in patients with MBC. Trial Design: Three cohorts of 10 patients with MBC in the following categories will be enrolled: ER and/or PR positive/HER2-negative, triple negative (TNBC) and MBC with brain metastases. An imaging phase will be followed by a treatment phase. The imaging phase consists of a baseline MRI scan, FMX infusion, and follow-up MRI scans at 1-4 and 24 h after infusion. The treatment phase begins 1-6 days after imaging and consists of nal-IRI 80 mg/m2 q2w. A pretreatment biopsy is required for correlative studies. Study Objectives: The primary objective of this multisite expansion is to investigate the feasibility of FMX quantitation in tumor lesions at multiple lesion sites in breast cancer. The secondary objective is to characterize the efficacy of nal-IRI in patients with metastatic breast cancer. Eligibility Criteria: The key inclusion criteria include patients with MBC, ECOG 0 or 1 with adequate bone marrow reserve and no prior topoisomerase 1 inhibitor or anti-VEGF treatment. ER and/or PR positive/HER2-negative and TNBC patients must have had 1-3 prior lines of chemotherapy in the metastatic setting and have at least 2 measurable lesions. Patients with brain metastasis must be neurologically stable and have new or progressive brain metastases after prior radiation therapy with at least one lesion measuring ≥ 1 cm in longest diameter on gadolinium-enhanced MRI. Status: This trial is currently recruiting patients. Citation Format: Sachdev JC, Ramanathan RK, Raghunand N, Anders C, Munster P, Minton S, Northfelt D, Blanchette S, Campbell K, Lee H, Klinz SG, Hendriks BS, Moyo V, Fitzgerald JB, Korn RL. A phase 1 study in patients with metastatic breast cancer to evaluate the feasibility of magnetic resonance imaging with ferrumoxytol as a potential biomarker for response to treatment with nanoliposomal irinotecan (nal-IRI, MM-398). [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr OT3-02-14.

417 Background: NAPOLI-1 is a global, randomized Phase 3 study evaluating nal-IRI—a nanoliposomal irinotecan—with or without 5-FU/LV in 417 patients with mPAC previously treated with gemcitabine-based therapy. Primary survival analysis was based on 313 events. Nal-IRI+5FU/LV significantly improved overall survival (OS, primary endpoint), 6.1 months (mo) vs 4.2 mo; with 5-FU/LV (unstratified hazard ratio [HR] = 0.67; P = 0.012). Primary endpoint was supported by improved progression-free survival, time to treatment failure, objective response and CA19-9 tumor marker response rates, and manageable toxicities. An updated analysis of OS, 6- and 12-month-survival estimates, and safety is presented. Methods: The updated descriptive analysis of OS, based on 378 events (25 May 2015), includes data from all randomized patients across the 3 arms. Results: After 378 OS events, nal-IRI+5-FU/LV (n = 117) retained an OS advantage relative to 5-FU/LV (n = 119): 6.2 mo (95% confidence interval [CI], 4.8–8.4) vs 4.2 mo (95% CI, 3.3–5.3) with an unstratified HR of 0.75 (P = 0.0417). In contrast, there was no OS advantage with nal-IRI monotherapy (n = 151) vs 5-FU/LV (n = 149): 4.9 mo [95% CI, 4.2–5.6] vs 4.2 mo [95% CI, 3.6–4.9], HR = 1.08; P = 0.5. Six-month survival estimates were 53% (95% CI, 44–62%) for nal-IRI+5-FU/LV vs 38% (95% CI, 29–47%) for 5-FU/LV; 12-month survival estimates were 26% (95% CI, 18-35%) for nal-IRI+5-FU/LV vs 16% (95% CI, 10–24%) for 5-FU/LV. With events in nearly all patients, the OS curves converge at ~20 mo with 19 patients (16.2%) surviving beyond 20 mo. This is a reason for attenuation of the HR estimate and unstratified log rank p-value. The most common grade 3+ adverse events occurring at a ≥ 2% incidence in the nal-IRI-containing arms were neutropenia, diarrhea, vomiting, and fatigue. Conclusions: In an updated analysis, the median OS benefit for nal-IRI+5FU/LV over 5-FU/LV was maintained, with a similar safety profile. Nal-IRI+5-FU/LV may be a new standard of care for patients with mPAC previously treated with gemcitabine-based therapy. Clinical trial information: NCT01494506.

MM-398 is a stable nanotherapeutic encapsulation of the prodrug irinotecan (CPT-11) with longer plasma half-life and higher tumor deposition due to an enhanced permeability and retention effect. Pancreatic cancer has responded poorly to many therapeutics, largely because of inadequate drug penetration due to poor vascularization and the highly aggressive, hypoxic nature of the disease. We sought to better understand how MM-398, a relatively large (100nm) liposomal nanotherapeutic, could be used treat pancreatic cancer. We have tested MM-398 in several pancreatic xenograft models: BxPC3 (KRAS wild type), AsPC-1(KRAS G12D) , Panc-1 (KRAS G12D) and MiaPaCa (KRAS G12C). All models demonstrated complete tumor regression at 20 mg/kg or a human equivalent dose of 60-120 mg/m2. At this same dose, MM-398 suppresses tumor growth in a gemcitabine insensitive AsPC-1 xenograft. MM-398 functionally blocked AsPC-1 tumor cell proliferation as measured by ki-67 staining; however, gemcitabine administered at its maximum tolerated dose did not impact proliferation. MM-398 is currently in multiple clinical trials, including a phase 3 trial for patients with advanced gemcitabine-resistant pancreatic cancer (NAPOLI-1). In order to further understand mechanisms driving response to MM-398, we screened and ranked several cell lines for their ability to convert irinotecan into the active metabolite, SN38. BxPC3 and HT-29 tumors ranked highest in ability to convert irinotecan to SN-38, as measured by HPLC. In a BxPC3 pancreatic orthotopic model which spontaneously metastasizes, 10 mg/kg MM-398 significantly reduced both primary and metastatic tumor load as measured by ex vivo biophotonic imaging of BxPC3luc cells to spleen, lung, liver, diaphragm and GI associated lymph nodes (p In summary, MM-398 induces tumor regression in multiple mouse models of pancreatic cancer, including an orthotopic metastatic model. MM-398 activity may be driven in part by the ability to modify tumor microenvironment parameters, such as hypoxia and vascularization, both of which limit efficacy of chemotherapeutic agents in the treatment of pancreatic cancer. These data support the continued investigation of MM-398 in pancreatic cancer. Citation Format: Nancy Paz, Peter Laivins, Clet Niyikiza, Ulrik Nielsen, Jonathan Fitzgerald, Ashish Kalra, Milind Chalishazar, Stephan Klinz, Jaeyeon Kim, Daryl Drummond, Dmitri Kirpotin, Victor Moyo, Eliel Bayever. MM-398/PEP02, a novel liposomal formulation of irinotecan, demonstrates stromal-modifying anticancer properties. [abstract]. In: Proceedings of the AACR Special Conference on Pancreatic Cancer: Progress and Challenges; Jun 18-21, 2012; Lake Tahoe, NV. Philadelphia (PA): AACR; Cancer Res 2012;72(12 Suppl):Abstract nr A63.

BACKGROUND: Epoetin-α initiated once weekly, followed by once-every-3-weeks maintenance, was effective and well tolerated for chemotherapy-induced anemia. This study evaluated a starting dose of epoetin-α 120,000U once every 3 weeks for chemotherapy-induced anemia using early and late initiation regimens. METHODS: Patients with baseline hemoglobin 11.0-12.0 g/dL were randomly assigned to early intervention with immediate epoetin-α (n = 68) or to standard intervention with epoetin-α when hemoglobin decreased to

Background: MM-302 is an antibody drug conjugated HER2-targeted liposomal doxorubicin in development by Merrimack Pharmaceuticals. MM-302 is designed to deliver doxorubicin to HER2-overexpressing cancer cells with minimal exposure to healthy cardiomyocytes. Results of the MM-302 phase I study as a monotherapy, in combination with trastuzumab and trastuzumab plus cyclophosphamide, are presented. Methods: 69 patients with HER2-positive metastatic breast cancer (mBC) were treated with either MM-302 alone (8, 16, 30, 40 and 50 mg/m2, Q4W) (Arm 1), MM-302 (30 and 40 mg/m2, Q4W) plus trastuzumab (4 mg/kg, Q2W) (Arm 2), MM-302 (30 mg/m2, Q3W) plus trastuzumab (6 mg/kg, Q3W) (Arm 3), MM-302 (30 mg/m2, Q3W) plus trastuzumab (6 mg/kg, Q3W) and cyclophosphamide (450 mg/m2, Q3W) (Arm 4). Patients on Arms 3 and 4 received a single 3-7 mg/m2 (approximately 10.8 mCi) dose of 64Cu-MM-302 followed by PET/CT to assess for MM-302 tumor deposition. Results: Patients received a median of 4 prior regimens for mBC. The most common Grade 3/4 side effect was neutropenia observed in 8 patients with 1 patient experiencing febrile neutropenia. Adverse events of any grade occurring in >20% of the population were constipation, cough, decreased appetite, diarrhea, dyspnea, fatigue, nausea, neutropenia, stomatitis and vomiting. Alopecia and hand foot syndrome were observed in 10% and 4% of patients respectively. 1 patient experienced a dose limiting toxicity DLT (febrile neutropenia) and a MTD was not reached at 50 mg/m2. 11 patients received cumulative anthracycline (previous exposure plus MM-302) exposure >550 mg/m2. LVEF reductions below 50% or a >10 percentage point drop in LVEF from baseline occurred in 6 patients. 1 patient experienced Grade 1 cardiac failure resulting in treatment discontinuation. In patients treated with ≥30 mg/m2 MM-302 (n = 49), alone or in combination with trastuzumab, the response rate (RR) was 12% and median progression free survival (mPFS) was 7.6 months (95% CI: 3.6-11.0). mPFS was 10.6 months (95% CI: 1.8-10.6) in the 13 patients receiving MM-302 plus trastuzumab and cyclophosphamide in Arm 4. Conclusions: MM-302 had a manageable safety profile in this study as a monotherapy, in combination with trastuzumab and with trastuzumab and cyclophosphamide. RR and mPFS in this heavily pretreated mBC population suggest further study is warranted. MM-302 at a dose of 30 mg/m2 Q3W in combination with trastuzumab is currently being evaluated in a randomized phase II trial (HERMIONE) in anthracycline naïve HER2-positive locally advanced/mBC patients previously treated with trastuzumab, pertuzumab and T-DM1. Citation Format: Patricia LoRusso, Ian Krop, Kathy Miller, Cynthia Ma, Barry A. Siegel, Anthony F. Shields, Istvan Molnar, Thomas Wickham, Joseph Reynolds, Karen Campbell, Bart Hendriks, Ty McClure, Victor Moyo, Pamela Munster. A phase I study of MM-302, a HER2-targeted PEGylated liposomal doxorubicin, in patients with HER2+ metastatic breast cancer. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr CT234. doi:10.1158/1538-7445.AM2015-CT234

234 Background: MM-398 is a nanoliposomal encapsulation of irinotecan. OS in the ITT population was significantly longer with MM-398+5FU/LV over 5FU/LV alone, and the most frequent grade 3+ AEs included neutropenia, fatigue, and GI effects (diarrhea and vomiting). Expanded, pre-specified analyses of the Phase 3 study are presented. Methods: Patients (n=417) with mPAC previously treated with gemcitabine-based therapy, were randomized 1:1:1 in an open-label study to receive: (A) MM-398 (120 mg/m2 IV over 90 min) q3w; (B) 5FU (2,000 mg/m2 over 24 h) plus racemic leucovorin (LV) (200 mg/m2 over 30 min) x 4w followed by 2w rest; or (C) combination of MM-398 (80 mg/m2 IV over 90 min) prior to 5FU (2,400 mg/m2 over 46 h) and racemic LV (400 mg/m2 over 30 min) q2w. The primary endpoint was OS. The Intent To Treat (ITT) population included all randomized patients; the Per Protocol (PP) population included patients who received at least 80% of the target dose in the first 6 weeks and did not violate any inclusion/exclusion criteria. Results: Analysis of the PP populations confirmed the favorable OS, which was also reflected by the PFS, ORR and CA19-9 levels, of the combination MM-398+5FU/LV arm over the control 5FU/LV arm. The MM-398 monotherapy arm did not show a statistically significant improvement in OS compared with the control arm. Analysis of subgroups, based on pretreatment characteristics including stage at diagnosis, time since initial histological diagnosis, prior lines of therapy, time since last prior therapy, and CA19-9 levels, consistently favored OS for the MM-398+5FU/LV arm over the 5FU/LV arm. Conclusions: Expanded analysis of the PP population and sensitivity analyses support the favorability of MM-398+5FU/LV over 5FU/LV, with a manageable safety profile. Clinical trial information: NCT01494506. [Table: see text]

Since Szent-Gyorgyi first purified ascorbic acid (vitamin C) in 1928 (1), a number of associations between ascorbic acid and iron metabolism have been described. At the molecular level, ascorbic acid mobilizes iron from the crystal core of ferritin in vitro by reducing Fe3 to Fe2 (2). Intracellularly, ascorbic acid enhances iron-induced translation of ferritin (3) by favoring the conversion of the iron regulatory protein (IRP) from the RNA binding form to aconitase (3). Ascorbic acid also retards degradation of ferritin by blocking lysosomal autophagy of ferritin and transformation to hemosiderin (4)(5). In humans, the oral administration of ascorbic acid enhances the absorption of non-heme iron from the diet (6) and leads to increases in serum iron in subjects with iron overload and ascorbic acid deficiency (7). Moreover, iron overload states are associated with reduced ascorbic acid concentrations, possibly because of increased catabolism of ascorbic acid (7)(8). The amount of labile iron in the cytosol influences the stability of transferrin receptor mRNA and the translation of ferritin mRNA (9)(10)(11). Posttranscriptional regulation occurs by means of an interaction between IRPs, proteins that sense changes in the chelatable intracellular iron pool, and iron-responsive elements located on untranslated regions of transferrin receptor mRNA and ferritin mRNA (12)(13)(14). In states of iron abundance, an IRP has aconitase activity and does not bind to iron-responsive elements, producing increased transferrin receptor mRNA degradation and increased ferritin mRNA translation. Conversely, when iron is deficient, an IRP loses aconitase activity and binds to iron-responsive elements, causing increased transferrin receptor mRNA stability and a repression of ferritin mRNA translation (15)(16). Thus, intracellularly, the presence of iron leads to inhibition of transferrin receptor expression and promotion of higher ferritin expression, whereas the deprivation of …

BACKGROUND Patients with estrogen receptor (ER)-positive and ER-negative breast carcinomas differ in terms of disease progression, treatment regimens, and prognosis. The mechanism underlying the biologic differences of the two groups is understood poorly. Array comparative genome hybridization (CGH) on breast carcinoma subtypes demonstrated a consistent association between loss in regions of chromosome 5q and ER-negative tumors. It was shown previously that early growth response gene 1 (EGR1) on 5q acts like a tumor-suppressor gene, with its expression repressed in breast carcinomas. METHODS To test the hypothesis that EGR1 is deleted differentially in ER-negative versus ER-positive breast carcinomas, fluorescence in situ hybridization was employed in this study to determine the EGR1 deletion status in 50 breast carcinoma specimens. Deletion status was measured by the signal ratio of EGR1/chromosome 5. Linear regression was used to assess the results. RESULTS The mean EGR1/chromosome 5 ratio for the ER-negative group was significantly lower compared with the same ratio for the ER-positive group (P < 0.001). Although grade alone was not significant for predicting the ratio, the interaction between ER status and grade was significant (P < 0.01): For ER-negative specimens, the higher the grade, the lower the EGR1/chromosome 5 ratio. CONCLUSIONS The EGR1 gene appeared to be deleted in ER-negative human breast carcinomas. Egr-1 may contribute to the pathogenesis of ER-negative breast carcinomas versus ER-positive breast carcinomas. Cancer 2005. © 2005 American Cancer Society.

The three predominant phenotypes of haptoglobin are Hp 1-1, Hp 2-1 and Hp 2-2 and there are functional differences between the different haptoglobin phenotypes. As haptoglobin polymorphism has been considered a candidate genetic factor in the pathophysiology of tuberculosis, we conducted this study to determine whether susceptibility to clinical pulmonary tuberculosis is related to the haptoglobin phenotype; a second study question was whether the haptoglobin phenotype is predictive of outcome in patients treated for this condition.

BACKGROUND Transferrin is the major iron binding protein in human plasma. In black persons, the transferrin CD phenotype has been associated with alterations in certain markers of iron status. OBJECTIVE We studied vitamin C status in a Zimbabwean population according to transferrin phenotype because vitamin C metabolism is influenced by iron-driven oxidative stress. DESIGN The study population consisted of 150 black African adults, 90 of whom were at risk of iron overload on the basis of high dietary iron content in the form of traditional beer. Transferrin phenotypes, indirect measures of iron status, and leukocyte ascorbic acid concentrations were determined. The in vitro rate of L-ascorbic acid depletion in sera from different transferrin phenotypes was investigated. RESULTS The transferrin phenotype frequencies of transferrin CC and CD were 0.893 and 0.107, respectively. The iron status of transferrin CC and CD subjects was similar. After adjustment for traditional beer consumption, baseline leukocyte vitamin C concentrations were significantly higher in 16 transferrin CD subjects ( +/- SE: 2.10 +/- 0.34 and 2.61 +/- 0.28 fmol/leukocyte in men and women, respectively) than in 134 transferrin CC subjects ( +/- SE: 1.65 +/- 0.11 and 1.99 +/- 0.11 fmol/leukocyte in men and women, respectively; P = 0.024). Oral administration of ascorbic acid (2.0 g every 24 h for 48 h) led to slower rises in leukocyte vitamin C concentrations in subjects with the transferrin CD phenotype than in subjects with the transferrin CC phenotype (P = 0.028). After in vitro supplementation of serum with 570 micromol vitamin C/L, the rate of L-ascorbic acid depletion was significantly lower in subjects of a transferrin CD phenotype than in subjects with the transferrin CC phenotype. CONCLUSION Transferrin polymorphism may affect vitamin C status in blacks.

Aim: Heregulin (HRG)-driven ErbB3 signaling mediates resistance to standard-of-care (SOC) cancer therapy in a variety of preclinical models. MM-121, a HRG-blocking anti-ErbB3 antibody, underwent clinical evaluation to determine if patients with advanced malignancies would derive benefit from the addition of MM-121 to their standard therapy. Potential predictive biomarkers were identified from a pre-specified set of mechanistic markers. Study BM+ n/N* BM+ Prevalence PFS HR in study PFS HR in measured BM PFS HR in BM+ PFS HR in BM- Ovarian 69/150 46% 1.03 [0.74-1.42] 1.10 [0.74-1.63] 0.40 [0.21-0.76] 2.02 [1.17-3.50] Lung 36/67 54% 0.82 [0.55-1.21] 0.91 [0.51-1.61] 0.39 [0.18-0.82] 2.43 [1.07-5.55] Breast 21/57 37% 0.75 [0.48-1.15] 0.68 [0.38-1.23] 0.35 [0.13-0.94] 0.99 [0.47-2.08] *n = BM + , N = patients with measured biomarkers Methods: Randomized Phase 2 studies were conducted in: i) platinum-resistant ovarian cancer, ii) EGFR wt NSCLC, and iii) ER/PR + , HER2- mBC. Patients were randomized to SOC therapy, with or without MM-121. Safety and clinical activity data from these studies have previously been presented. Tumor tissue was acquired from each patient and five pre-specified biomarkers were measured and correlated with clinical benefit: HRG, betacellulin, EGFR, HER2, and ErbB3. Protein levels were determined by quantitative IHC (qIHC) and mRNA levels by RT-PCR and RNA in-situ hybridization (RNA-ISH). Results: Among 464 patients (220 ovarian, 115 breast, 129 lung), RNA-ISH data were available from 224 patients (157 ovarian, 67 lung), qIHC from 252 (174 ovarian, 78 lung), and RT-PCR from 175 (105 ovarian, 57 breast, 13 lung). Of the five biomarkers, the most predictive of response was HRG mRNA: patients with detectable HRG in pre-treatment biopsies or high HRG in archived tissue blocks responded poorly to SOC therapy and benefited most from MM-121. In addition, benefit was largely restricted to patients with low ErbB2. Hazard ratios for PFS were calculated, defining biomarker positive (BM+) patients: Ovarian cancer, detectable HRG and low ErbB2; Lung cancer, detectable HRG; and, Breast cancer, high HRG. PFS hazard ratios with 95% CI and prevalence of the BM+ and BM- subpopulations are provided below. Conclusions: Heregulin is a potential biomarker for poor response to SOC therapy and a potential predictor of clinical benefit from MM-121 in late-stage ovarian, lung, and breast cancers. Disclosure: G. MacBeath is an employee of Merrimack Pharmaceuticals and holds stock in the company; B. Adiwijaya is an employee of Merrimack Pharmaceuticals, the sponsor of this clinical research, and holds stock in the company; J. Liu is an unpaid advisor for Merrimack Pharmaceuticals and was a Principal Investigator for one of the clinical studies included in this analysis; L.V. Sequist is an upaid advisor for Merrimack Pharmaceuticals and was a Principal Investigator of one of the clinical studies included in this analysis; E. Pujade-Lauraine serves as an upaid advisor to Merrimack Pharmaceuticals and Sanofi. He was also a lead investigator for one of the clinical studies included in this analysis; M. Higgins is an unpaid advisor to Merrimack Pharmaceuticals and Sanofi. She was a Principal Investigator of one of the clinical studies included in this analysis; I. Tabah-Fisch is an employee of Sanofi, a sponsor of the clinical studies summarized in this abstract, and holds stock in the company; J. Pearlberg is an employee of Sanofi, a sponsor of this clinical research, and holds stock in the company; V. Moyo, W. Kubasek, R. Nering and A. Czibere: Is an employee of Merrimack Pharmaceuticals, a sponsor of the clinical research, and holds stock in the company.

Aim: MM-151 is an oligoclonal combination of three IgG1, anti-EGFR antibodies designed to bind distinct non-overlapping EGFR epitopes and inhibit ligand-mediated signal amplification. MM-151's molecular composition enables antagonism of clinically relevant EGFR ligand mixtures, EGFR down-regulation and immune effector function (ADCC, CDC). A Phase 1 study was initiated to assess the safety, tolerability, PK, immunogenicity and preliminary clinical activity of MM-151. Methods: 69 patients were enrolled on 3 schedules (QW, Q2W, and Q3W) at escalating doses using standard 3 + 3 design. Response was assessed per RECIST criteria every 8 weeks. Patients continued on study until disease progression or unacceptable toxicity. Results: Results presented are based on preliminary data as of Apr. 25, 2014. 69 patients (median age 63 years; 33 male, 36 female) have been enrolled across 3 dosing schedules. 69 patients were evaluable for safety and 46 evaluable for efficacy. The most common tumor types were CRC (28 [41%]), NSCLC (9 [13%]), SCCHN (5 [7%]), and pancreatic (5 [7%]). An MTD has not been reached and dose escalation continues. Most adverse events were CTCAE grades 1 and 2. Infusion related reaction (IRR) was the most common AE (47 [68.1%]); however, this was managed with premedication and an optimized infusion schedule. The most common non-IRR AEs were comprised of EGFR-pathway toxicities, including rash (54 [78%]), hypomagnesemia (17 [25%]), mucositis (8 [12%]) and diarrhea (15 [22%]). Initial biomarker data in a subset of patients suggest that IRR relates to engagement of the innate immune system, shown in pre- and post - dose cytokine and peripheral blood flow cytometry data. Partial responses were observed in 2 CRC patients and a total of 8 (29% of mCRC) patients had SD for > 4 months (2 of the 8 had SD for 20.1 and 19.8 months). At doses > 9 mg/kg QW, trough total antibody levels at steady state were in expected therapeutic range. Conclusions: Results to date show that MM-151 has an acceptable safety profile and objective clinical activity in CRC. Updated safety, efficacy and preliminary biomarker data will be presented. Disclosure: C. Lieu: Consultant for Sanofi Aventis; L. Power, C. Sloss, J. Kearns, R. Nering, V. Moyo and B. Wolf: employee of Merrimack Pharmaceuticals, stock ownership. All other authors have declared no conflicts of interest.

Aim: Activation of HER2/HER3 heterodimers by HER3's ligand heregulin (HRG) is a putative resistance mechanism for HER2-targeted therapies. MM-111 is a HER2/HER3 bispecific antibody fusion protein designed to inhibit HRG activated HER3 signaling in HER2+ tumors. This study evaluated biomarkers in patient samples from a multi-arm Phase 1 study of MM-111 combined with standard of care HER2-targeting regimens: capecitabine + cisplatin + trastuzumab (T); lapatinib (L) +/- T; paclitaxel (P) + T; L + P + T; docetaxel + T. All patients were required to have advanced HER2+ cancer. Methods: The following biomarkers were assessed in formalin fixed, paraffin-embedded archived tissue: HER2 by 5 methods including immunohistochemistry (IHC) scored using 0/1 + /2 + /3+ and image analysis (optical density) systems, quantitative immunofluorescence (qIF), fluorescent in situ hybridization (FISH), and reverse transcription polymerase chain reaction (PCR); HER3 by qIF and PCR; and HRG, betacellulin, and EGF receptor by PCR. Results: 86 patients [46 breast, 15 gastro-esophageal (GE), 11 bladder, 14 other cancers] were treated and archived tissue was received from 71 patients. All 71 samples were assessable by IHC, 69 by qIF, 64 by FISH, and 46 by PCR. The 5 HER2 assessments correlated well with each other and the correlations were independent of indication. Compared to other indications, patients with GE cancer tended to have higher HRG and HER3 expression. Stratified by indication and treatment, increased HER2 expression correlated with longer progression free survival (PFS) across all patients, particularly GE patients, but the relative contribution of MM-111 or trastuzumab could not be determined. Higher betacellulin expression was associated with longer PFS for regimens containing lapatinib. Conclusions: This study supports use of the described biomarker assays for analysis of samples from a randomized Phase 2 study of MM-111 in HER2+ GE cancer. Biomarker analyses of archived and newly acquired biopsy samples will be performed in the Phase 2 study to provide further insight for the role of HER2, HER3, and HRG in the response of HER2+ cancer to MM-111-containing therapy. Disclosure: A. Kudla, B. Adiwijaya, V. Paragas, K. Kawash, S. Frye, C.F. McDonaghand V. Moyo: Employee of Merrimack Pharmaceuticals with stock options; A.A. Garcia: Recipient of research funding from Merrimack Pharmaceuticals; C.S. Denlinger: Recipient of research funding from Merrimack Pharmaceuticals. P. Conkling: Recipient of funding from Virginia Oncology Associates and US Oncology. S. Anthony: Consultant for Paradigm.All other authors have declared no conflicts of interest.