Andecaliximab/GS-5745 Alone and Combined with mFOLFOX6 in Advanced Gastric and Gastroesophageal Junction Adenocarcinoma: Results from a Phase I Study

Purpose: Matrix metalloproteinase-9 (MMP9) is implicated in protumorigenic processes. Andecaliximab (GS-5745, a monoclonal antibody targeting MMP9) was evaluated as monotherapy and in combination with mFOLFOX6.Patients and Methods: Three dosages of andecaliximab monotherapy [200, 600, and 1800 mg i.v. every 2 weeks (q2w)] were investigated in patients with advanced solid tumors (n = 13 in a 3+3 design). After determining a recommended dose, patients with advanced HER2-negative gastric/gastroesophageal junction (GEJ) adenocarcinoma (n = 40) received 800 mg andecaliximab + mFOLFOX6 q2w. Pharmacokinetics, pharmacodynamics, safety, and efficacy were assessed.Results: Andecaliximab monotherapy demonstrated no dose-limiting toxicity (DLT) in any cohort, displaying target-mediated drug disposition at the lowest dose (200 mg) and linear pharmacokinetics at higher doses. Based on target engagement, recommended doses for further study are 800 mg q2w or 1,200 mg q3w. Maximal andecaliximab target binding, defined as undetectable andecaliximab-free MMP9 in plasma, was observed in the gastric/GEJ adenocarcinoma cohort. We observed no unusual toxicity, although there were four deaths on study not attributed to andecaliximab treatment. In first-line patients (n = 36), median progression-free survival (PFS) was 9.9 months [95% confidence interval (CI), 5-13.9 months], and the overall response rate (ORR) was 50%. Among all patients (n = 40), median PFS was 7.8 (90% CI, 5.5-13.9) months, and ORR was 48%, with a median duration of response of 8.4 months.Conclusions: Andecaliximab monotherapy achieved target engagement without DLT. Andecaliximab + mFOLFOX6 showed encouraging clinical activity without additional toxicity in patients with HER2-negative gastric/GEJ adenocarcinoma. A phase III study evaluating mFOLFOX6 ± andecaliximab in this setting is ongoing. Clin Cancer Res; 24(16); 3829-37. ©2018 AACR.

Momelotinib versus best available therapy in patients with myelofibrosis previously treated with ruxolitinib (SIMPLIFY 2): a randomised, open-label, phase 3 trial

BACKGROUND

The Janus kinase (JAK) inhibitor ruxolitinib is the only approved therapy for patients with symptomatic myelofibrosis. After ruxolitinib failure, however, there are few therapeutic options. We assessed the efficacy and safety of momelotinib, a JAK 1 and JAK 2 inhibitor, versus best available therapy (BAT) in patients with myelofibrosis who had suboptimal responses or haematological toxic effects with ruxolitinib.

METHODS

In this randomised, phase 3, open-label trial, patients were screened for eligibility from 52 clinical centres in Canada, France, Germany, Israel, Italy, Spain, the UK, and the USA. Patients who had myelofibrosis and previous ruxolitinib treatment for at least 28 days who either required red blood cell transfusions while on ruxolitinib or ruxolitinib dose reduction to less than 20 mg twice a day with at least one of grade 3 thrombocytopenia, anaemia, or bleeding at grade 3 or worse, with palpable spleen of at least 5 cm and without grade 2 or greater peripheral neuropathy were included in the study. Patients were randomly assigned (2:1) to either 24 weeks of open-label momelotinib 200 mg once a day or BAT (which could include ruxolitinib, chemotherapy, steroids, no treatment, or other standard interventions), after which all patients could receive extended momelotinib treatment. Patients were randomly assigned to treatment by an interactive web response system and the randomisation was stratified by transfusion dependence and by baseline total symptom score (TSS). Results were analysed on an intention-to-treat basis. The primary endpoint was a reduction by at least 35% in the spleen volume at 24 weeks compared with baseline. Safety analyses included adverse event monitoring. The trial is registered with ClinicalTrials.gov, number NCT02101268.

FINDINGS

Between June 19, 2014, and July 28, 2016, 156 patients were recruited to the study; 104 received momelotinib and 52 received BAT. BAT was ruxolitinib in 46 (89%) of 52 patients. 73 (70%) of 104 patients in the momelotinib group and 40 (77%) of 52 patients in the BAT group completed the 24-week treatment phase. Seven (7%) of 104 patients in the momelotinib group and three (6%) of 52 in the BAT group had a reduction in the spleen volume by at least 35% compared with baseline (proportion difference [Cochran-Mantel-Haenszel method], 0·01; 95% CI -0·09 to 0·10), p=0·90). The most common grade 3 or worse adverse events were anaemia (14 [14%] of 104 in the momelotinib group vs seven [14%] of 52 in the BAT group), thrombocytopenia (seven [7%] vs three [6%]), and abdominal pain (one [1%] vs three [6%]). Peripheral neuropathy occurred in 11 (11%) of 104 patients receiving momelotinib (one of which was grade 3) and in no patients in the BAT group. Serious events were reported for 36 (35%) patients in the momelotinib group and 12 (23%) of patients in the BAT group. Deaths due to adverse events were reported for six patients (6%) receiving momelotinib (acute myeloid leukaemia [n=2], respiratory failure [n=2, with one considered possibly related to momelotinib], cardiac arrest [n=1, considered possibly related to momelotinib], and bacterial sepsis [n=1]); and four patients (8%) receiving BAT (lung adenocarcinoma [n=1], myelofibrosis [n=1], and sepsis [n=2]).

INTERPRETATION

In patients with myelofibrosis previously treated with ruxolitinib, momelotinib was not superior to BAT for the reduction of spleen size by at least 35% compared with baseline.

FUNDING

Gilead Sciences, Inc.

SIMPLIFY-1: A Phase III Randomized Trial of Momelotinib Versus Ruxolitinib in Janus Kinase Inhibitor-Naïve Patients With Myelofibrosis

Purpose We evaluated the efficacy and safety of momelotinib, a potent and selective Janus kinase 1 and 2 inhibitor (JAKi), compared with ruxolitinib, in JAKi-naïve patients with myelofibrosis. Patients and Methods Patients (N = 432) with high risk or intermediate-2 risk or symptomatic intermediate-1 risk myelofibrosis were randomly assigned to receive 24 weeks of treatment with momelotinib 200 mg once daily or ruxolitinib 20 mg twice a day (or per label), after which all patients could receive open-label momelotinib. The primary end point was a ≥ 35% reduction in spleen volume at 24 weeks of therapy. Secondary end points were rates of symptom response and effects on RBC transfusion requirements. Results A ≥ 35% reduction in spleen volume at week 24 was achieved by a similar proportion of patients in both treatment arms: 26.5% of the momelotinib group and 29% of the ruxolitinib group (noninferior; P = .011). A ≥ 50% reduction in the total symptom score was observed in 28.4% and 42.2% of patients who received momelotinib and ruxolitinib, respectively, indicating that noninferiority was not met ( P = .98). Transfusion rate, transfusion independence, and transfusion dependence were improved with momelotinib (all with nominal P ≤ .019). The most common grade ≥ 3 hematologic abnormalities in either group were thrombocytopenia and anemia. Grade ≥ 3 infections occurred in 7% of patients who received momelotinib and 3% of patients who received ruxolitinib. Treatment-emergent peripheral neuropathy occurred in 10% of patients who received momelotinib (all grade ≤ 2) and 5% of patients who received ruxolitinib (all grade ≤ 3). Conclusion In JAKi-naïve patients with myelofibrosis, 24 weeks of momelotinib treatment was noninferior to ruxolitinib for spleen response but not for symptom response. Momelotinib treatment was associated with a reduced transfusion requirement.

A phase 2 study of momelotinib, a potent JAK1 and JAK2 inhibitor, in patients with polycythemia vera or essential thrombocythemia

Momelotinib is a potent inhibitor of JAK1 and JAK2 that demonstrated efficacy in patients with primary and secondary myelofibrosis. This phase 2, open-label, randomized study evaluated the efficacy and safety of oral once-daily momelotinib (100mg and 200mg) for the treatment of polycythemia vera (PV) and essential thrombocythemia (ET). The primary endpoint for PV was overall response rate (ORR), defined as the proportion of patients with hematocrit <45%, white blood cell count <10×10⁹/L, platelet count ≤400×10⁹/L, and resolution of palpable splenomegaly, each lasting ≥4 weeks. The definition of ORR for ET excluded the hematocrit component. A total of 39 patients (28 PV, 11 ET) were enrolled, with 28 patients receiving ≥12 weeks of treatment. The study was terminated due to limited efficacy. Two patients (ORR 5.1%) met the primary efficacy endpoint (both PV 200mg). Predose plasma levels of momelotinib were stable over time. A total of 31 (79.5%) patients experienced momelotinib-related adverse events (AEs), the most frequent being headache (23.1%), dizziness (18.0%), somnolence (15.4%), nausea (15.4%), and fatigue (15.4%). Three patients experienced serious AEs (7.7%), with 1 considered related to momelotinib (dyspnea). Peripheral neuropathy occurred in 7 (17.9%) patients (4 PV, 3 ET).

A phase II, open-label, randomized study to evaluate the efficacy and safety of GS-5745 combined with nivolumab versus nivolumab alone in subjects with unresectable or recurrent gastric or gastroesophageal junction adenocarcinoma

TPS4141

Background: GS-5745 is a monoclonal antibody that inhibits matrix metalloproteinase 9 (MMP9), an extracellular enzyme involved in matrix remodeling, tumor growth, and metastasis. Inhibiting MMP9 is expected to block paracrine signaling and metastasis and to alter the immune microenvironment within the tumor. Results from the ATTRACTION-2 Phase III trial showed the PD-1 inhibitor nivolumab significantly improved overall survival (OS), progression-free survival (PFS), and overall response rate (ORR) in patients with heavily pre-treated advanced gastric or gastroesophageal junction cancer. Preclinical studies indicate that selective inhibition of MMP9 can inhibit immune-suppressive myeloid cell polarization, regulatory T cell generation, desmoplasia, and the destruction of ligands for CXCR3 (a critical chemokine receptor that enables effector T cell trafficking). In combination with a checkpoint inhibitor, CD8+, CD4+ and CD44+ cytotoxic T cells are significantly increased in a checkpoint-refractory model, suggesting that MMP9 inhibition could relieve immune suppression. Methods: This phase 2, open-label, randomized study investigates the efficacy and safety of GS-5745 combined with nivolumab versus nivolumab alone in patients with unresectable or recurrent gastric or gastroesophageal adenocarcinoma. 120 patients will be randomized to either GS-5745 800mg IV + nivolumab 3mg/kg IV, or nivolumab alone. Treatment will be administered every 2 weeks and stratified by PD-L1 status. CT will be performed every 8 weeks to evaluate response. The primary endpoint of the study is ORR; secondary endpoints include PFS, OS, and occurrence of adverse events. Key inclusion criteria: metastatic or inoperable adenocarcinoma of the stomach or GEJ which has progressed after ≥1 prior systemic therapy, ECOG performance status ≤1, RECISTv1.1 measureable disease, archival tissue adequate for PD-L1 evaluation. Exploratory biomarkers correlated with study drug response will also be evaluated. Enrollment opened September 2016. Clinical trial information: NCT02864381.

A phase 3 randomized, double-blind, placebo-controlled study to evaluate the efficacy and safety of GS-5745 combined with mFOLFOX6 as first-line treatment in patients with advanced gastric or gastroesophageal junction adenocarcinoma

TPS4139

Background: GS-5745 is a monoclonal antibody that inhibits matrix metalloproteinase 9 (MMP9), an extracellular enzyme involved in matrix remodeling, tumor growth, and metastasis. Inhibiting MMP9 blocks paracrine signaling and metastasis and alters the tumor immune microenvironment. GS-5745 (800 mg q 2 weeks) with mFOLFOX6 was examined in a Phase 1b study in 40 patients with gastric and GEJ adenocarcinoma (GS-US-296-0101), and demonstrated encouraging activity without added toxicity (10% CR, median PFS 10.7 mo (Shah et al ASCO GI 2017, a108)). Decreased free MMP9 suggested inhibition of MMP9 enzymatic activity by GS-5745. These data support the hypothesis that GS-5745 treatment inhibits MMP9 activity and that the inhibition may lead to improved clinical outcomes. Methods: This phase 3, randomized, double-blind, multicenter study investigates the efficacy and safety of GS-5745 combined with mFOLFOX6 in subjects with untreated gastric and GEJ adenocarcinoma. Total of 430 eligible subjects with advanced gastric and GEJ cancer will be randomized in a 1:1 manner to mFOLFOX6 plus GS-5745 or mFOLFOX6 plus placebo. Stratification factors include ECOG status (0 v 1), geographic region (Latin America v All other countries), and primary tumor site (gastric v GEJ). CT or MRI scans will be performed every 8 weeks to evaluate response to treatment. mFOLFOX6 will be administered on Days 1 and 15 of each 28-day treatment cycle for a total of 6 cycles followed thereafter by leucovorin (LV) and 5-fluorouracil (5-FU) dosing on Days 1 and 15 of each 28-day treatment cycle until disease progression. GS-5745/placebo 800 mg will be infused on Days 1 and Day 15 of each 28 day cycle until disease progression. Primary endpoint is OS, and secondary endpoints include PFS, ORR (RECIST 1.1), and safety. The study is designed to have an 85% power to detect clinically meaningful improvement in overall survival at the one-sided significance level of 0.025. The association of exploratory biomarkers with study drug response will also be evaluated. Enrollment opened Oct. 2015. Clinical trial information: NCT02545504.

Phase 3 trial of momelotinib (MMB) vs ruxolitinib (RUX) in JAK inhibitor (JAKi) naive patients with myelofibrosis (MF)

7000

Background: MMB, an oral JAKi, has been shown in early trials to reduce spleen volume, improve disease associated symptoms (Sx) and improve RBC transfusion (Tx) requirements in patients (pts) with MF. This study was designed to test non-inferiority of MMB vs RUX in splenic volume reduction and Sx amelioration, and superiority in Tx requirement, in JAKi naïve MF pts. Methods: Eligibility: MF, IPSS high risk, Int-2, or symptomatic Int-1; palpable spleen ≥5cm; platelets ≥ 50 K/μl, and no Gr ≥2 peripheral neuropathy (PN). Stratification by Tx dependency and platelets (<100, 100-200 and >200 K/μl). Pts were randomized 1:1 to 24 wks of MMB 200 mg qd + RUX placebo or RUX 20 mg bid (or modified per label) + MMB placebo, after which all pts could receive open label MMB. Assessments: spleen volume by MRI, and pt reported Sx using a daily eDiary of modified MPN-SAF Total Sx Score (TSS). Primary endpoint was splenic response rate (SRR; ≥35% reduction in volume from baseline) at 24 wks. Secondary endpoints, evaluated sequentially at 24 wks, were rates of TSS response (≥50% reduction from baseline), RBC Tx independence (TI), RBC Tx dependence (TD) and of RBC Tx . Results: 175 of 215 (81%) and 201 of 217 (93%) pts randomized to MMB and RUX, respectively, completed the 24 wk DB phase. Efficacy results are shown in Table. Most common Gr ≥3 AEs in the DB phase with MMB were thrombocytopenia (7%) and anemia (6%), and with RUX were anemia (23%), thrombocytopenia (5%) and neutropenia (5%). Gr ≥3 infections occurred in 7% of MMB and 3% of RUX pts. Treatment emergent PN occurred in 22 (10%) of MMB (all Gr ≤2) and 10 (5%) of RUX (9 Gr ≤2, 1 Gr 3) pts in DB phase, none discontinuing study drug for PN. Overall, AEs led to study drug D/C in 13% of MMB and 6% of RUX pts in DB phase. Conclusions: In pts with JAKi naive MF, 24 weeks of MMB is non-inferior to RUX for spleen response but not for symptom response. MMB treatment is associated with a reduced transfusion requirement. NCT01969838. [Table: see text]

Phase 3 randomized trial of momelotinib (MMB) versus best available therapy (BAT) in patients with myelofibrosis (MF) previously treated with ruxolitinib (RUX)

7001

Background: MMB, an oral JAK inhibitor, has been shown in early trials to reduce spleen volume, improve disease associated symptoms (Sx) and improve RBC transfusion requirements in patients (pts) with MF. This study of previously RUX treated pts with MF tested the superiority of MMB vs BAT in splenic volume reduction, Sx amelioration, and transfusion requirement at 24 weeks. Methods: Eligibility included primary or post-ET/PV MF; DIPSS high risk, Int-2, or symptomatic Int-1; prior RUX ≥4 weeks who either required transfusions or dose reduction to <20 mg BID with at least one of Gr ≥3 thrombocytopenia, anemia, or bleed; palpable spleen ≥5cm; and no Gr ≥2 peripheral neuropathy. Stratification was by transfusion dependency and baseline TSS (modified MPN-SAF Total Sx Score) <18 or ≥18. Pts were randomized 2:1 to 24 weeks of open-label MMB 200 mg QD or BAT. Assessments included spleen volume by MRI, and patient-reported Sx using a daily eDiary for TSS. 1° endpoint was splenic response rate (SRR; ≥35% reduction in volume from baseline). 2°endpoints, evaluated sequentially, were rates of TSS response (TSS RR; ≥50% reduction from baseline), RBC transfusion, RBC transfusion independence (TI) and RBC transfusion dependence (TD). Results: 73 of 104 (70%) and 40 of 52 (77%) pts receiving MMB or BAT, respectively, completed the 24 week randomized treatment phase. BAT for 88% of pts included RUX, and 27% of pts were on RUX in combination with other drugs. Efficacy results are in Table. The most common Gr ≥3 adverse events in MMB pts were anemia (13%) and thrombocytopenia (7%), and in BAT pts, anemia (13%), thrombocytopenia (6%) and abdominal pain (6%); treatment emergent peripheral neuropathy occurred in 11 (11%) of MMB (1 Gr3) and in no BAT pts. Conclusions: In previously RUX-treated patients with MF, 24 weeks of MMB was not superior to BAT for SRR, but significantly better in improving disease related symptoms and transfusion independence. Clinical trial information: NCT02101268. [Table: see text]

Updated results of a phase 1 study combining the matrix metalloproteinase 9 inhibitor GS-5745 and mFOLFOX6 in patients with advanced gastric/gastroesophageal junction cancer

108

Background: GS-5745 is a monoclonal antibody inhibitor of matrix metalloproteinase 9 (MMP9), an extracellular enzyme involved in matrix remodeling, tumor growth, and metastasis. We present updated data from a phase I study of patients (pts) with advanced gastric/gastroesophageal adenocarcinoma (GC) treated with GS-5745 and mFOLFOX6 (NCT01803282). Methods: Following a monotherapy dose finding stage, pts with Human Epidermal Growth Factor Receptor 2 (HER2)-negative advanced or metastatic GC received mFOLFOX6 and GS-5745 (800 mg IV) every 2 weeks. Treatment continued until disease progression, unacceptable toxicity or withdrawal of consent. Response was assessed every 8 weeks per RECIST version 1.1 criteria. Results: As of April 2016, 40 pts were enrolled in the expanded cohort (12 continue to receive GS-5745). The most frequently observed adverse events (AEs) of any grade include nausea (62.5%), fatigue (60%), diarrhea (45%), peripheral neuropathy (45%) and neutropenia (37.5%). Grade ≥ 3 AEs observed in ≥ 10% of pts include neutropenia (20%) and nausea and neutrophil count decreased (10% each). Among 29 treatment naïve pts, median progression free survival (PFS) is 12 (90% confidence interval (CI) 5.5-18) months (mos), median duration of response (DOR) 10.6 mos and objective response rate (ORR) of 55.2%. For all pts (n=40), PFS is 7.8 (90% CI 5-13.9) mos, median DOR 10.1 mos and ORR of 50%. Median baseline circulating MMP9 was 44.7 (range 16.8-1395.3) ng/mL and all 34 patients with post-baseline samples had undetectable MMP9 levels within 8 weeks. Conclusions: The combination of GS-5745 with mFOLFOX6 is well tolerated and demonstrates activity, particularly in treatment naïve pts. Reduction in circulating MMP9 level after treatment with GS-5745 suggests specific target engagement. A phase III registration study of mFOLFOX6 +/- GS-5745 in treatment naïve metastatic GC pts is underway. Clinical trial information: NCT01803282.

Updated results of a phase 1 study combining the matrix metalloproteinase 9 inhibitor GS-5745 with gemcitabine and nab-paclitaxel in patients with advanced pancreatic cancer

363

Background: GS-5745 is a monoclonal antibody inhibitor of matrix metalloproteinase 9 (MMP9), an extracellular enzyme involved in matrix remodeling, tumor growth, and metastasis. We present data from patients (pts) with advanced pancreatic adenocarcinoma enrolled in an ongoing multi-indication phase 1 study (NCT01803282) evaluating GS-5745. Methods: Following a monotherapy dose finding stage, pts with locally advanced or metastatic pancreatic cancer received gemcitabine (G) + nab-paclitaxel (Abraxane, A) and GS-5745 800 mg IV every 2 weeks. Treatment continued until disease progression, unacceptable toxicity or withdrawal of consent. Response was assessed every 8 weeks per RECIST version 1.1 criteria. Results: As of April 2016, 36 pts were enrolled (1 continues to receive GS-5745). The most frequently observed adverse events (AEs) of any grade include fatigue (75%), alopecia (55.6%), peripheral edema (55.6%) and nausea (50%). Grade ≥ 3 AEs observed in ≥ 10% of pts included neutropenia (25%), anemia (19.4%) and fatigue (13.9%). The median progression free survival (PFS) for all pts is 7.8 (90% confidence interval (CI) = [6.1, 11]) months (mos), median duration of response (DOR) is 5.8 mos and the objective response rate (ORR) is 44.4%. Of the 31 pts who were treatment naïve in the metastatic setting, median PFS is 9.2 (90% CI = [6.1, 11]) mos, median DOR 5.8 mos and the ORR 51.6%. Median baseline circulating MMP9 was 44.3 (range 12.4-549.6) ng/mL and 31 of 32 patients with post-baseline samples had undetectable MMP9 levels within 8 weeks. Conclusions: GS-5745+GA demonstrated numerically higher ORR and PFS compared to historical data without additional toxicity. Additionally, reductions in circulating MMP9 levels post treatment suggest target engagement by GS-5745 . These results suggest this combination may warrant additional study in first line metastatic pancreatic adenocarcinoma. Clinical trial information: NCT01803282.

A phase 3 randomized, double-blind, placebo-controlled study to evaluate the efficacy and safety of GS-5745 combined with mFOLFOX6 as first-line treatment in patients with advanced gastric or gastroesophageal junction adenocarcinoma

TPS217

Background: GS-5745 is a monoclonal antibody that inhibits matrix metalloproteinase 9 (MMP9), an extracellular enzyme involved in matrix remodeling, tumor growth, and metastasis. Inhibiting MMP9 is expected to block paracrine signaling and metastasis and to alter the immune microenvironment within the tumor. GS-5745 (800 mg every 2 weeks) with mFOLFOX6 was examined in a Phase 1b study in 40 patients with gastric and GEJ adenocarcinoma (GS-US-296-0101), and demonstrated encouraging activity without added toxicity. Additionally, decreased serum biomarkers suggested inhibition of MMP9 enzymatic activity by these agents. These data support the hypothesis that GS-5745 treatment inhibits MMP9 activity and that the inhibition may lead to improved clinical outcomes. Methods: This phase 3, randomized, double-blind, multicenter study investigates the efficacy and safety of GS-5745 combined with mFOLFOX6 in subjects with untreated gastric and GEJ adenocarcinoma. Total of 430 eligible subjects with advanced gastric and GEJ cancer will be randomized in a 1:1 manner to mFOLFOX6 plus GS-5745 or mFOLFOX6 plus placebo. Stratification factors include ECOG status (0 v 1), geographic region (Latin America v All other countries), and primary tumor site (gastric v GEJ). CT or MRI scans will be performed every 8 weeks to evaluate response to treatment. mFOLFOX6 will be administered on Days 1 and 15 of each 28-day treatment cycle for a total of 6 cycles followed thereafter by leucovorin (LV) and 5-fluorouracil (5-FU) dosing on Days 1 and 15 of each 28-day treatment cycle until disease progression. GS-5745/placebo 800 mg will be infused on Days 1 and Day 15 of each 28 day cycle until disease progression. Primary endpoint is OS, and secondary endpoints include PFS, ORR (RECIST 1.1), and safety. The study is designed to have an 85% power to detect clinically meaningful improvement in overall survival at the one-sided significance level of 0.025. The association of exploratory biomarkers with study drug response will also be evaluated. Enrollment opened Oct. 2015. Clinical trial information: NCT02545504.

Evaluating collagen neoepitopes as pharmacodynamic biomarkers of GS-5745, an MMP9 inhibitor, in advanced gastric cancer

58

Background: Cancer is characterized by continuous remodeling of the extracellular matrix (ECM) through a process of degradation and replacement of ECM components, such as collagens. Matrix-metalloproteinase 9 (MMP9) is involved in this remodeling and its inhibition is hypothesized to reduce ECM turnover. MMP9 expression is limited in healthy tissues, but high in tumor epithelia, infiltrating inflammatory cells and fibroblasts. Collagen I and III fragments (neoepitopes C1M and C3M) in blood may provide a measure of tumor MMP activity (BMC Cancer 13:554. 2013). GS-5745 is a monoclonal antibody that specifically inhibits MMP9 and has shown efficacy in combination with chemotherapy in advanced gastric cancer in an ongoing ph I study of multiple cancer types (NCT01803282). Exploratory analyses of collagen neoepitopes from patients in the gastric cancer cohort are reported here. Methods: C1M and C3M were measured by ELISA in serum samples (Nordic Bioscience). Healthy volunteer (HV) samples were age-matched. Pharmacodynamic evaluation and association with clinical outcomes were assessed by non-parametric tests; nominal p-values are reported. Results: Pharmacodynamic Evaluation (Table):Baseline (BL) levels of C1M and C3M were higher in gastric cancer patients than HVs. C1M and C3M displayed a pharmacodynamic response after 1 treatment cycle. Inhibition of C1M continued to decline with treatment. Association with Best Overall Response:There was no association of BL C1M or C3M level with best overall response. 13 of 20 responders had decreased C1M at C2D1; however, of the 3 patients with progressive disease, none had an on-treatment decrease in C1M. Conclusions: These data suggest an association between circulating C1M as a pharmacodynamic biomarker of GS-5745 in combination with chemotherapy in gastric cancer patients. Circulating neoepitope biomarkers will continue to be explored in all ongoing and future oncology GS-5745 studies. Clinical trial information: NCT01803282. [Table: see text]

Folate receptor-α (FOLR1) expression and function in triple negative tumors

Folate receptor alpha (FOLR1) has been identified as a potential prognostic and therapeutic target in a number of cancers. A correlation has been shown between intense overexpression of FOLR1 in breast tumors and poor prognosis, yet there is limited examination of the distribution of FOLR1 across clinically relevant breast cancer subtypes. To explore this further, we used RNA-seq data from multiple patient cohorts to analyze the distribution of FOLR1 mRNA across breast cancer subtypes comprised of estrogen receptor positive (ER+), human epidermal growth factor receptor positive (HER2+), and triple negative (TNBC) tumors. FOLR1 expression varied within breast tumor subtypes; triple negative/basal tumors were significantly associated with increased expression of FOLR1 mRNA, compared to ER+ and HER2+ tumors. However, subsets of high level FOLR1 expressing tumors were observed in all clinical subtypes. These observations were supported by immunohistochemical analysis of tissue microarrays, with the largest number of 3+ positive tumors and highest H-scores of any subtype represented by triple negatives, and lowest by ER+ tumors. FOLR1 expression did not correlate to common clinicopathological parameters such as tumor stage and nodal status. To delineate the importance of FOLR1 overexpression in triple negative cancers, RNA-interference was used to deplete FOLR1 in overexpressing triple negative cell breast lines. Loss of FOLR1 resulted in growth inhibition, whereas FOLR1 overexpression promoted folate uptake and growth advantage in low folate conditions. Taken together, our data suggests patients with triple negative cancers expressing high FOLR1 expression represent an important population of patients that may benefit from targeted anti-FOLR1 therapy. This may prove particularly helpful for a large number of patients who would typically be classified as triple negative and who to this point have been left without any targeted treatment options.

Phase II clinical trial of amatuximab, a chimeric antimesothelin antibody with pemetrexed and cisplatin in advanced unresectable pleural mesothelioma

PURPOSE

Amatuximab is a chimeric monoclonal antibody to mesothelin, a cell surface glycoprotein highly expressed in malignant pleural mesothelioma (MPM). On the basis of its synergy with chemotherapy in preclinical studies, we evaluated the antitumor activity of amatuximab plus pemetrexed and cisplatin in patients with unresectable MPM.

EXPERIMENTAL DESIGN

In a single-arm phase II study, amatuximab (5 mg/kg) was administered on days 1 and 8 with pemetrexed (500 mg/m(2)) and cisplatin (75 mg/m(2)) on day 1 of 21-day cycles for up to six cycles. Patients with response or stable disease received amatuximab maintenance until disease progression. Primary endpoint was progression-free survival (PFS) at 6 months. Secondary endpoints were overall survival (OS), response rate, and safety.

RESULTS

Eighty-nine patients were enrolled at 26 centers. Median of five cycles (range, 1-6) of combination treatment was administered, and 56 (63%) patients received amatuximab maintenance. Combination therapy resulted in no overlapping toxicities. Eleven patients (12.4%) had amatuximab-related hypersensitivity reactions. Responses included partial responses in 33 (40%) and stable disease in 42 (51%). Six-month PFS rate was 51% [95% confidence interval (CI), 39.1-62.3)], median PFS was 6.1 months (95% CI, 5.8-6.4), and median OS was 14.8 months (95% CI, 12.4-18.5) with 29 patients alive at data cut-off.

CONCLUSIONS

Amatuximab with pemetrexed and cisplatin was well tolerated with objective tumor response or stable disease rate of 90% by independent radiologic review. Although PFS was not significantly different from historical controls, the median OS was 14.8 months with a third of patients alive and 5 continuing to receive amatuximab at the time of analysis.

Increased expression of folate receptor-α (FRA) in triple-negative breast cancer: A potential therapeutic target

1037

Background: Folate receptor alpha (FRA the product of the FOLR1 gene) has been identified as a potential prognostic and therapeutic target in a number of cancers. A correlation has been shown between intense expression of FRA in breast tumors and poor prognosis, yet little is known about FOLR1/FRA expression across clinically relevant breast cancer subtypes. Methods: 131 breast cancer tumors including 4 benign, 33 ER+, 26 HER2+, and 68 triple negative (TN) were constructed into tissue microarrays (TMAs). FRA expression was analyzed by immunohistochemistry (IHC) using a high affinity FRA antibody. Tumor membrane staining intensity was scored by a pathologist as negative (0), weak (1+), moderate (2+) and strong (3+). The percent of cells within each tissue core stained at each intensity was recorded to calculate an H-score. The H-score is a weighted score that captured both the proportion of positive staining and intensity for each tumor. H-score values can range from zero (no membrane staining) to a maximum of 300 (100% membrane staining at 3+). H-scores for each patient sample were averaged over 3 TMA cores. The mean H-scores for each tumor subtype and the percentage of 3+ staining in >30% of tumor cells were compared by a Mann-Whitney test. The distribution of FOLR1 mRNA was completed using a TCGA RNA-seq dataset from 691 breast tumors classified as ER+, HER2+ and TN. FOLR1 levels of TN versus ER+ and HER2+ were compared by a Mann-Whitney test. Results: The mean H-score for the benign tumors was 0, ER+ (13.31), HER2+ (39.36), TN (119.02). The median H-score for the benign tumors was 0, ER+ (0), HER2+ (7.5), TN (127.5). The TN tumors mean and median H scores were significantly higher than benign, ER+ or HER2+ (p<0.001). The largest percentage of 3+ staining in >30% of tumor cells was observed in TN tumors (36.7%) and lowest in ER+ tumors (0%) (p<0.001). TN tumors had significantly higher levels of FOLR1 mRNA compared to ER+ and HER2+ subtypes (p<0.0001). Conclusions: Our data indicate that expression of FRA is highly prevalent in TN tumors and is supported by FOLR1 mRNA levels. Anti-FRA therapy may represent an important therapeutic intervention in TNBC who to this point have no active targeted treatment options.

Single-agent lapatinib for HER2-overexpressing advanced or metastatic breast cancer that progressed on first- or second-line trastuzumab-containing regimens

BACKGROUND

This phase II study evaluated the efficacy and safety of lapatinib in patients with human epidermal growth factor receptor 2 (HER2)-positive advanced or metastatic breast cancer that progressed during prior trastuzumab therapy.

PATIENTS AND METHODS

Women with stage IIIB/IV HER2-overexpressing breast cancer were treated with single-agent lapatinib 1250 or 1500 mg once daily after protocol amendment. Tumor response according to RECIST was assessed every 8 weeks. HER2 expression was assessed in tumor tissue by immunohistochemistry and FISH.

RESULTS

Seventy-eight patients were enrolled in the study. Investigator and independent review response rates [complete response (CR) or partial response (PR)] were 7.7% and 5.1%, and clinical benefit rates (CR, PR, or stable disease for >or=24 weeks) were 14.1% and 9.0%, respectively. Median time to progression was 15.3 weeks by independent review, and median overall survival was 79 weeks. The most common treatment-related adverse events were rash (47%), diarrhea (46%), nausea (31%), and fatigue (18%).

CONCLUSIONS

Single-agent lapatinib has clinical activity with manageable toxic effects in HER2-overexpressing breast cancer that progressed on trastuzumab-containing therapy. Studies of lapatinib-based combination regimens with chemotherapy and other targeted therapies in metastatic and earlier stages of breast cancer are warranted.