Lebedinsky, Claudia

4147 Background: Retrospective studies of phosphorylated STAT3 (pSTAT3, a regulator of gene expression) in cancer-lineage cells have suggested it is a biomarker of poor prognosis. We analyzed data from 3 phase 3 RCTs (BRIGHTER [T1; NCT02178956], CO.23 [T2; NCT01830621], CanStem111P [T3; NCT02993731]) to evaluate the prognostic impact of pSTAT3 on OS in GI cancer patients (pts). Methods: pSTAT3 was evaluated in archival tumor tissue from pts with gastric or gastroesophageal junction adenocarcinoma (T1), colorectal cancer (T2), or pancreatic cancer (T3) who received standard of care in the control arms (CTL) of their respective trials. pSTAT3 positive (+) or negative (−) status was determined by detecting pSTAT3 in both tumor and tumor microenvironment (TME) cells in a laboratory-developed immunohistochemistry (IHC) assay (T1; T2), later developed into the investigational pSTAT3 IHC D3A7 assay (Agilent Technologies, Inc.) (T3). The positivity cutoff requires a sample have both a TME score of 2 and ≥5% of tumor cells staining positively for pSTAT3. Pre-analytical variables (eg, specimen collection, handling, and processing), tumor indication, and slight differences in the assays used for each study may contribute to relative differences in evaluable rates between studies. In an exploratory analysis, OS was compared in pSTAT3+ vs pSTAT3− pts via an unstratified log-rank test. Results: In each study, intent-to-treat pts with evaluable pSTAT3 results were considered pSTAT3-evaluable. This abstract includes pSTAT3-evaluable pts randomized to the CTL arms (T1: n/N=248/357, 69.5%; T2: n/N=110/144, 76.4%; T3: n/N=243/569, 42.7%). Baseline characteristics are presented in the table. Median (m) OS was shorter in pts with pSTAT3+ tumors across all studies (T1 hazard ratio [HR]=1.32 [95% confidence interval (CI): 1.00, 1.74]; T2 HR=2.40 [1.50, 3.83]; T3 HR=1.08 [0.77, 1.50]). Conclusions: In pSTAT3-evaluable populations from 3 RCTs across GI cancers, CTL pts with pSTAT3+ (vs pSTAT3−) tumors had shorter mOS. These results suggest that pSTAT3 positivity may be a biomarker of poor clinical outcome. Clinical trial information: NCT02178956; NCT01830621; NCT02993731. [Table: see text]

7109 Background: We previously reported results of treating MF patients with 3 cycles of 300, 400, or 500 mg of SAR302503 (NCT01420770; Blood 2012;120:21 Abs 2837). This is a report of efficacy and safety after 6 cycles. Methods: Patients ≥18 years of age with intermediate-2 or high-risk MF and splenomegaly were eligible. SAR302503 is administered orally, once a day in consecutive 4-week cycles until disease progression or unacceptable toxicity. Spleen response (≥35% reduction in spleen volume vs baseline) was assessed by MRI/CT (blinded independent central review). Results: 31 patients were enrolled (n=10 in the 300 and 400 mg groups; n=11 to 500 mg). Risk status was balanced in all but the 300 mg group (70% high-risk). Most patients were JAK2V617F positive (90%) and blood transfusion independent (81%). Spleen response rates at the end of cycle (EOC) 6 (secondary end point) were 30% (3/10) in the 300 mg group, 60% (6/10) with 400 mg, and 55% (6/11) with 500 mg compared with EOC 3 rates of 30%, 50%, and 64%, respectively. One patient on 500 mg who had a spleen response at EOC 3 (39% reduction), but not at EOC 6 (25% reduction) had dose reductions to 200 mg due to anemia. Median number of cycles was 13 (range, 2–17) and 24 patients have been on treatment >12 months. SAR302503 reduced baseline constitutional symptoms at the EOC 3, with the greatest responses for night sweats in 14/15 patients (93%), itching 10/14 (71%), early satiety and abdominal pain, each in 10/18 (56%). Most common adverse events were anemia and diarrhea, with grade 3–4 rates of 58% and 13%, respectively. The rate of grade 3–4 thrombocytopenia was 16%. There was no grade 3–4 neutropenia. The diarrhea rate tended to decrease after the first 2 treatment cycles. There have been no reports of withdrawal syndrome after stopping SAR302503. Median JAK2V617F allele burden was 93% at baseline, 87% at the EOC 3, and 78% at EOC 6 in 19/26 patients who had available samples. The expression of 22 of 97 cytokines was significantly regulated (≥1.5 fold difference; p<0.05) after cycle 1. Conclusions: In this Phase II trial, continued treatment with SAR302503 was associated with clinically meaningful reductions in splenomegaly. Symptom data will be updated. Clinical trial information: NCT01420770.

TPS6641 Background: Hydroxyurea is widely used to treat patients with high-risk PV and ET. However, some patients are either clinically resistant to hydroxyurea or have unacceptable side effects, supporting the need for active therapeutic options in this setting. SAR302503 is an orally administered selective JAK-2 inhibitor that reduced symptom burden and provided a durable clinical benefit, including a reduction in the JAK2V617F allele burden, with an acceptable safety profile in a Phase 1/2 trial of patients with primary myelofibrosis (MF), post-PV MF, or post-ET MF (J Clin Oncol 2011;29:789; Pardanani, ASH 2011; Abs 3838). Based on the results in MF, in October 2011 we initiated a Phase 2 trial to evaluate SAR302503 for the treatment of patients with PV and ET who are resistant or intolerant to hydroxyurea (NCT01420783; ARD12042). Methods: Eligibility criteria include age of at least 18 years, ECOG PS 0–2, and hydroxyurea resistant PV or ET as defined by European LeukemiaNet Consensus Criteria (Blood 2009;113:4829). Patients are being randomized (1:1:1) to receive 100, 200, or 400 mg of SAR302503 orally once daily in consecutive 28-day cycles for at least 8 cycles in the absence of progression or unacceptable toxicity. The primary end points will be assessed after the completion of 8 cycles and are: for PV, the proportion of patients maintaining a hematocrit below 45% without phlebotomy for at least 3 months; for ET, the proportion of patients with a platelet count lower than 400 × 109/L for at least 3 months. Secondary objectives include safety, response rate, pharmacokinetics, pharmacodynamics as measured by JAK2V617F allele burden and STAT3 phosphorylation inhibition, assessment of disease-related symptoms, and quality of life. Enrollment of the planned total of 90 patients is ongoing at approximately 45 sites globally. Twelve patients have been enrolled as of January 2012.

TPS6639 Background: SAR302503 is an orally administered selective JAK-2 inhibitor being evaluated for the treatment of MF. In a phase 1 study, SAR302503 reduced spleen size and disease-related symptoms and provided clinical benefit, including a reduction in the JAK2V617F allele burden, with an acceptable safety profile in patients with primary MF, post-PV MF, or post-ET MF (J Clin Oncol 2011;29:789). An ongoing open-label extension of this trial confirmed the durability of those results and found that doses between 400–500 mg/day of SAR302503 represented the optimal balance between safety and efficacy (Pardanani, ASH 2011;Abs 3838). These results led us to initiate a Phase 3 trial in December 2011 to evaluate SAR302503 at doses of 400 mg/day and 500 mg/day, compared with placebo, for the treatment of patients with MF (NCT01437787; EFC12153). Methods: Eligibility criteria include age of at least 18 years, platelets >50,000/µl, ECOG PS 0–2, and a diagnosis of high- or intermediate-risk 2 primary MF, post-PV MF, or post-ET MF according to IPSS criteria (Blood 2009;113:2895). Patients are being randomized (1:1:1) to receive 400 mg or 500 mg of SAR302503 or placebo orally once a day for at least 6 consecutive 28-day cycles. Assigned treatment will continue as long as patients are deriving benefit or until progression or unacceptable toxicity. Cross-over is allowed after 6 cycles or in case of progression before completion of 6 cycles according to predefined criteria. The primary endpoint is spleen response (≥35% reduction in spleen volume by MRI/CT at the end of cycle 6). Key secondary objectives are symptom response rate and durability of spleen response. Additional secondary endpoints include assessment of allele burden and bone marrow fibrosis reduction. It is planned to randomize 75 patients per treatment group at approximately 130 sites worldwide.

7110 Background: Abnormal cytokine expression may represent an inflammatory response that contributes to the clinical phenotype of MF. Some constitutional symptoms (eg. fever, fatigue, pruritus, cachexia) are thought to be caused by elevated cytokines. In phase I/II studies, SAR302503 reduced splenomegaly and constitutional symptoms in patients with MF. Here, we report the effects of SAR302503 on the expression of 97 cytokines in MF patients enrolled in a Phase II study (NCT01420770) and the relationship to clinical response (spleen size), pharmacokinetic (PK) exposure, and body weight changes. Methods: Thirty-one patients were randomized to receive 300, 400, or 500 mg of SAR302503 orally, once daily, continuously in 4-week cycles. Plasma cytokines were measured at baseline and at the end of 4, 8, and 12 weeks of treatment using a microsphere-based immuno-multiplex assay (Rules Based Medicine). Results: Complete sample sets were available for 29/31 patients. A total of 28 cytokines predominantly involved in immune/inflammation pathways were regulated ≥1.5-fold (ANOVA P<0.05) and of these, 19 were regulated at all time points, indicating rapid and sustained modulation by JAK2 inhibition. At 4 weeks, 16 cytokines were down-regulated, including TNFα, IL-1RA, and IL-18, and 6 were up-regulated, including leptin, EPO, and adiponectin. Hierarchical clustering of the 22 regulated cytokines enriched patients into spleen responder (≥35% reduction in spleen volume by MRI) and non-responder groups, suggesting a link between cytokine modulation and clinical response. Moderate correlations (P<0.05) with spleen volume reduction at the end of week 12 were seen for a subset of regulated cytokines, including adiponectin and TNFα. Levels of the majority of the regulated cytokines tended to correlate with steady state PK exposure at week 4. A positive association with weight changes at week 24 were observed for leptin and adiponectin at week 4 (P<0.05). Conclusions: This analysis shows that SAR302503 treatment modulated the expression of circulating cytokines in MF patients in association with changes in clinical activity, PK exposure, and symptom improvement (weight gain). Clinical trial information: NCT01420770.

Abstract Abstract 2837 Introduction: Treatment with the JAK2 selective inhibitor SAR302503 reduced spleen size, disease-related symptoms, and the JAK2 V617F allele burden, with an acceptable safety profile in patients with primary MF, post-PV MF, or post-ET MF in a Phase I/II study (J Clin Oncol 2011;29:789, ASH 2011; Abs 3838). The objective of this Phase II study is to assess the efficacy, safety, pharmacokinetics (PK), and pharmacodynamics (PD) of 3 doses of SAR302503. Methods: Patients with intermediate-2 or high-risk primary MF, post-PV MF, or post-ET MF were randomized to 1 of 3 dose groups of SAR302503 (300, 400, or 500 mg per day). Eligibility criteria included age ≥18 years, ECOG PS 0–2, and an enlarged spleen (length ≥5 cm). SAR302503 was taken orally, once a day, in consecutive 28-day cycles until disease progression or unacceptable toxicity. The primary endpoint is the absolute change in spleen volume at the end of cycle 3 assessed by MRI with independent central review. Secondary endpoints include spleen response (≥35% reduction in spleen volume vs baseline), safety, symptom response (MPN-SAF), PK, and PD (changes in leukocyte pSTAT3). Results: From August–December 2011, at total of 31 patients were enrolled (n=10 in the 300 and 400 mg groups; n=11 to 500 mg). Risk status (intermediate-2 vs high) was balanced in the 400 mg and 500 mg groups (∼50%), whereas the 300 mg group had more high-risk patients (70%). The majority of patients (88% to 91%) had the JAK2 V617F mutation and most (∼80%) were blood transfusion independent. Mean (median) percentage reductions in spleen volume vs baseline at the end of cycle 3 were 30% (26%) in the 300 mg group, 33% (31%) with 400 mg, and 42% (38%) with 500 mg. A spleen response at the end of cycle 3 was seen in 30% of patients (3/10) in the 300 mg group, 50% (5/10) in the 400 mg group, and 64% (7/11) in the 500 mg group. Patients with constitutional symptoms at baseline in all groups reported a symptom response at the end of cycle 3, with at least a 2-point improvement in or resolution of night sweats in 93% (14/15) of patients, itching in 71% (10/14), early satiety in 56% (10/18), abdominal pain in 56% (10/18), and abdominal discomfort in 50% (10/20). Safety was evaluated in all patients. The most common grade 3–4 hematological adverse event (laboratory) was anemia, with rates across the 300, 400, and 500 mg doses of 33%, 30%, and 55%, respectively. Rates of grade 3–4 thrombocytopenia were 20%, 0, and 9%. There was no grade 3–4 neutropenia. Most common grade 3–4 nonhematological events were diarrhea (10%, 20%, 0), nausea (10%, 10%, 0), and vomiting (10%, 10%, 0). Adverse events in the 300 mg group led to discontinuation in 2 patients: 1 patient had grade 3 anemia, and 1 patient with pre-existing intermittent mild transaminase elevations and polyarthritis had hepatic failure, but completely recovered after discontinuation. No other grade 3–4 increases of AST, ALT, or bilirubin were observed. No deaths were due to an adverse event. Following repeated once-daily oral doses, SAR302503 exposure increased in a dose-dependent manner, with a median time to maximum plasma concentration of 2 to 3 hours. Steady state was achieved by cycle 1 day 15 (C1D15), with a 2.95- to 3.88-fold accumulation of drug. Time-dependent pSTAT3 inhibition was observed at all doses, with the highest mean percentage decreases from baseline (range) occurring at C1D15 (44% to 52%) and C2D1 (40% to 51%). The relationship between PK and PD pSTAT3 suppression can be described by an Emax model. There was also a correlation between percentage of pSTAT3 inhibition and spleen response rate at C1D15 and C2D1 and evidence of a steady state exposure-response relationship for spleen volume reduction at the end of cycle 3. Conclusions: In this Phase II trial, treatment with SAR302503 was associated with clinically meaningful reductions in splenomegaly and improvements in constitutional symptoms. SAR302503 was generally well tolerated in this trial and adverse events were consistent with the known safety profile. Time-dependent decreases in pSTAT3 and exposure-response correlations can be demonstrated across the three doses tested. Sponsored by Sanofi (NCT01420770) Disclosures: Talpaz: Novartis: Research Funding, Speakers Bureau; BMS: Research Funding; ARIAD: Research Funding; Deciphera: Research Funding. Gabrail:Sanofi: Research Funding. Lebedinsky:Sanofi: Employment, Equity Ownership. Gao:Sanofi: Employment, Equity Ownership. Liu:Sanofi: Employment, Equity Ownership. Pardanani:YM BioSciences: Clinical trial support, Clinical trial support Other; BMS: Clinical trial support, Clinical trial support Other; Sanofi: Clinical trial support Other.

Abstract Background We previously reported that patients with MF enrolled in a randomized Phase II study of fedratinib (SAR302503) (ARD11936; NCT01420770) had clinically meaningful reductions in splenomegaly and improvements in MF-associated constitutional symptoms after 24 weeks of treatment (Haematologica 2013;98:S1113). Here, we report updated efficacy and safety results from this study after 48 weeks of treatment (end of Cycle 12). Methods Patients with intermediate risk-2 or high-risk MF were randomized to receive once-daily fedratinib at doses of 300 mg, 400 mg, or 500 mg, for consecutive 4-weekly cycles, until disease progression or unacceptable toxicity. Eligible patients were aged ≥18 years, with palpable splenomegaly (5 cm below costal margin), and a platelet count ≥50 × 109/L. The primary measure for this study was percent change in spleen volume from baseline at the end of Cycle 3 (Blood 2012:120;Abstract 2837. Haematologica 2013;98:S1113). Endpoints for the current analysis included spleen response (≥35% reduction in spleen volume from baseline, assessed by a blinded independent central review by MRI), safety, and changes in bone marrow fibrosis (BMF). Results A total of 31 patients were randomized and treated: median age 63 years, 52% male, 58% primary MF, 58% high-risk MF, 90% JAK2V617F positive. The median numbers of treatment cycles were 12, 14, and 13 in the 300 mg, 400 mg and 500 mg dose groups, respectively, with median durations of exposure of 48.2, 56.2, and 52.4 weeks. At the cut-off date for this analysis, 21 patients (68%) remained on treatment; the most common reasons for treatment discontinuation were adverse events (AEs) (n=5) and withdrawal of consent (n=2). Overall, 58% (18/31) of patients achieved a spleen response at any time during treatment. The median spleen response duration was >35 weeks at all doses (Table). At Week 48, a spleen response was achieved by 30% (3/10), 80% (8/10), and 45% (5/11) of patients in the 300 mg, 400 mg, and 500 mg groups, respectively. Responses were generally maintained across all treatment groups. From Week 24 to Week 48 two additional patients achieved a spleen response (both in the 400 mg group), while one patient in the 500 mg group did not maintain a response (this patient had a fedratinib dose reduction to 200 mg). Changes in BMF up to Week 48 are being evaluated. The most common non-hematologic AE was diarrhea, with a Grade 3 rate of 13% (4/31 patients) but no Grade 4 cases were recorded. The rates of diarrhea decreased after the first cycle of treatment; from Cycle 2, the incidence of diarrhea (any grade) did not exceed 16% (5/31) at any cycle, and only one case of diarrhea was reported at Week 48 (end of Cycle 12). Anemia was the most-common hematologic toxicity, with a Grade 3 rate of 58% (18/31); no Grade 4 cases were reported. All Grades thrombocytopenia occurred in 55% (17/31) of patients, Grade 3 in three patients, and Grade 4 in two patients. Discontinuation of treatment due to AEs occurred in five patients over the 48 weeks (300 mg [n=2]; 400 mg [n=2]; 500 mg [n=1]), with two cases reported after Week 24 (dyspnea and leukocytosis [400 mg]; anemia and thrombocytopenia [500 mg]). There were 2 deaths (one in the 300 mg group due to unknown reasons [85 days after fedratinib discontinuation] and one in the 500 mg group due to disease progression [36 days after fedratinib discontinuation]). No cases of leukemic transformation were reported. Conclusions This updated analysis of the ARD11936 Phase II trial shows that treatment with fedratinib results in durable reductions in splenomegaly in patients with MF. No additional safety signals were observed with prolonged exposure to fedratinib. This study was sponsored by Sanofi. Disclosures: Pardanani: Sanofi, Bristol Myers Squibb, PharmaMar and JW Pharma: Clinical trial support Other. Jamieson:J&J, Roche: Research Funding; Sanofi: Membership on an entity’s Board of Directors or advisory committees. Lebedinsky:Sanofi: Employment. Gao:Sanofi: Employment. Talpaz:Novartis, Bristol-Myers Squibb, Ariad, Deciphera: Research Funding; Novartis, Bristol-Myers Squibb, Ariad, Deciphera: Speakers Bureau.

Abstract Janus kinase-2 (JAK2)/STAT pathway activation is commonly observed in myeloproliferative neoplasms and plays an important role in disease development and progression. The V617F activating mutation in the JAK2 pseudokinase domain is found in 95% of patients with polycythemia vera (PV) and in 50-70% of patients with primary myelofibrosis (MF) or essential thrombocythemia (ET). Studies have shown the clinical efficacy of JAK2 inhibitors in treating MF in terms of a reduction in splenomegaly and relief of constitutional symptoms. A reduction in the JAK2V617F allele burden after treatment with a JAK2-targeted agent could be a surrogate for a disease-modifying effect of this therapy. To demonstrate this, a robust method that can accurately measure the JAK2V617F allele burden is required. Here, we report the development of a sensitive quantitative PCR (qPCR) assay to determine the JAK2V617F allele burden in patients treated with SAR302503, the validation of the assay in a Phase 0 clinical study and implementation in a phase II study using samples from patients with MF. The assay demonstrated robust performance, with high sensitivity (LLOD=0.05% and LLOQ=0.5%) and accuracy. A phase 0 study in MF, PV, and ET patients showed that (1) there was minimal intra-subject sampling variability in JAK2V617F allele burden, and (2) whole-blood samples are stable for at least 48 hours at ambient conditions for DNA preparation without a significant impact on JAK2V617F allele burden measurement.Of the 31 patients with intermediate-2 or high-risk MF enrolled in a phase II clinical study (NCT01420770), baseline samples were available for 29 patients and of these, 26 were JAK2V617F-positive using this assay. Of the 19/26 patients for whom samples were available at all 3 time points, the median allele burden was 93% at baseline, 87% at the end of Cycle 3, and 78% at the end of Cycle 6. Among the 24 patients who were JAK2V617F-positive and for whom spleen measurements were available at the end of Cycle 6, a total of 15 (63%) had a spleen response (≥ 35% reduction in spleen volume by MRI versus baseline). In contrast, two JAK2V617F-negative patients did not have a spleen response. Patients with baseline allele burden levels of 0 to &lt;25%, 25% to 75%, and ≥75% showed spleen response rates of 50%, 44%, and 69%, respectively, at the end of Cycle 6. JAK2V617F allele burden will continue to be assessed every 3 cycles. Longer follow up is needed to determine the clinical effect of allele burden reduction. Citation Format: Feng Liu, Moshe Talpaz, Animesh Pardanani, Catriona Jamieson, Nashat Gabrail, Ayalew Tefferi, Tianlei Lei, Rita Greco, Francisco Adrian, Nikki Daskalakis, Claudia Lebedinsky, Pamela Cohen, Donald Bergstrom. Determination of JAK2V617F allele burden in a phase II study of patients with myelofibrosis treated with SAR302503 using a sensitive and robust allele-specific qPCR assay. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr LB-294. doi:10.1158/1538-7445.AM2013-LB-294