Daskalakis, Nikki

Abstract Background SAR650984 (SAR) is a naked humanized IgG1 monoclonal antibody (mAb) that binds selectively to the human surface antigen CD38 highly expressed in multiple myeloma cells and other hematological malignancies. SAR kills tumor cells via 3 different biological mechanisms: Antibody-dependent cellular-mediated cytotoxicity (ADCC), complement-dependent cytotoxicity (CDC) and Induction of apoptosis (pro-apoptosis). Here we present preliminary data from the ongoing first in human, Phase I dose escalation study of SAR in patients with selected CD38+ hematological malignancies. (clinicaltrials.gov: NCT01084252) Objectives The primary objective is to determine the maximum tolerated dose (MTD). Secondary objectives include characterization of safety, pharmacokinetics (PK), pharmacodynamics (PD), immunogenicity and disease response. Methods SAR is administered as a single agent IV infusion every week (QW) or every 2 weeks (Q2W) to adult patients with selected CD38+ hematological malignancies who have progressed on or after standard therapy or for whom no effective standard therapy exists. An accelerated dose escalation schedule was used for the first 5 dose levels (DL) (0.0001 mg/kg to 0.1 mg/kg Q2W), with one evaluable patient per DL unless DLT was experienced. All subsequent DL (0.3 mg/kg, 1 mg/kg, 3 mg/kg, 5mg/kg, 10 mg/kg, 20 mg/kg Q2W and 10 mg/kg QW), followed the classic 3+3 design for dose escalation based on DLT. Results 32 patients have been treated across all DLs including 3 patients with NHL, 2 with CLL, and 27 with MM. The 20 mg/kg Q2W and 10 mg/kg QW DLs are currently being evaluated and the MTD has not been reached. DLTs have been limited to Grade (G) 2 infusion reactions during cycle 1 with 1 at DL 0.3 mg/kg and 1 at DL 3.0 mg/kg. This was mitigated by the implementation of routine pretreatment with methylprednisone, diphenhydramine, ranitidine and acetaminophen. The most frequent occurring adverse events (≥ 10%) all DL, regardless of causality, are fatigue (46.9%), nausea (31.3%), pyrexia (28.1%), cough (25%), vomiting (21.9%), hypercalcemia (18.8%), with headache, constipation, bone pain, chills and diarrhea each occurring in 15.6% of patients. In addition, pneumonia, anemia, dysgeusia and hypokalemia each occurred in 12.5% of patients. Serious adverse events considered related to therapy include G 3 pneumonia (6.3%) associated with fever (3.1%), hyperglycemia (3.1%) and one Grade 2 infusion reaction (3.1%). Of the 19 patients treated at DL 1.0 mg/kg to 10 mg/kg Q2W, 1 had CLL, 1 had NHL and 17 had MM. The 17 MM patients were older and heavily pretreated patients; median age of 64 years (range: 55-74); and median of seven prior regimens (range: 2-14). All MM patients had received prior lenalidomide and bortezomib. The median time from diagnosis to first SAR650984 dosing was 6. 8 years (range 1.8 – 16.8 years). Responses in this group (fig 1), according to EBMT MM criteria, included 1 PR at 1 mg/kg (n = 3) and 5 mg/kg (n=3), and 1 MR at DL 3 mg/kg (n = 6). The 10 mg/kg DL demonstrated 3 PR and 2 SD among 6 MM patients treated. For the 19 patients treated at or above the 1 mg/kg DL the median time on treatment is 8 weeks (range 2-50 weeks). Immunogenicity studies show no anti-SAR antibodies. Receptor Occupancy could be detected from DL 1 mg/kg and reached a range of 84.1 to 97.7 % at 10 mg/kg. PK analysis show a more than dose proportional increase of exposure over the 0.03 to 10 mg/kg dose range with clearance in a similar range between 5 mg/kg and 10 mg/kg. No accumulation was observed based on Cmax at cycle 2 over the 0.03 to 3 mg/kg dose range. Tumor growth inhibition threshold was reached at Cmax for 1 patient at DL 5 mg/kg and 5 patients at DL 10 mg/kg. Conclusion The safety profile of SAR is predictable and manageable and the MTD has not been reached. SAR demonstrates encouraging single agent activity in patients with heavily pretreated RRMM and warrants further evaluation in this patient population. Disclosures: Zheng: sanofi: Employment. Daskalakis:sanofi: Employment.

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 <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