4SC (Germany)

Abstract(1)BackgroundAberrant activation of the Hedgehog (HH)/GLI pathway in stem-like tumor initiating cells (TIC) is a frequent oncogenic driver signal in various human malignancies. Remarkable efficacy of anti-HH therapeutics led to the approval of HH inhibitors targeting the key pathway effector Smoothened (SMO) in basal cell carcinoma and acute myeloid leukemia. However, frequent development of drug resistance and severe adverse effects of SMO inhibitors pose major challenges that require alternative treatment strategies targeting HH/GLI in TIC downstream of SMO. We therefore investigated members of the casein kinase 1 (CSNK1) family as novel drug targets in HH/GLI driven malignancies.(2)MethodsWe genetically and pharmacologically inhibited CSNK1D in HH-dependent cancer cells displaying either sensitivity or resistance to SMO inhibitors. To address the role of CSNK1D in oncogenic HH signaling and tumor growth and initiation, we quantitatively analyzed HH target gene expression, performed genetic and chemical perturbations of CSNK1D activity and monitored oncogenic transformation of TIC in vitro and in vivo using 3D clonogenic tumor spheroid assays and xenograft models.(3)ResultsWe show that CSNK1D plays a critical role in controlling oncogenic GLI activity downstream of SMO. We provide evidence that inhibition of CSNK1D interferes with oncogenic HH signaling in both SMO-inhibitor sensitive and resistant tumor settings. Furthermore, genetic and pharmacologic perturbation of CSNK1D decreases the clonogenic growth of GLI-dependent tumor-initiating cancer cells in vitro and in vivo.(4)ConclusionsPharmacologic targeting of CSNK1D represents a novel therapeutic approach for the treatment of both SMO inhibitor sensitive and resistant tumors.

3625 Background: Resminostat is a novel oral HDAC inhibitor with broad activity in various cancer models. In CRC models, resminostat revealed synergistic effects with 5-FU and irinotecan/SN-38, indicating its (re-)sensitization potential when applied in combination therapy. Furthermore, resminostat downregulates thymidylate synthase, involved in drug resistance to 5-FU and effectively inhibits HDAC2, one of the target enzymes believed to critically support development of CRC. The phase I/II SHORE trial investigates resminostat in combination with FOLFIRI in patients previously treated with 5-FU. Methods: Patients (pts) with advanced CRC having previously received 5-FU alone or in combination with other agents who were scheduled for FOLFIRI in second or later treatment lines were included. The phase I comprised an open-label, inter-patient, ‘3+3’ dose escalation design with increasing doses of resminostat combined with standard FOLFIRI. Pts received resminostat on 5 consecutive days, followed by a 9-day drug free period (‘5+9’ scheme, i.e. 14-day cycles). On days 3 and 4 of each cycle (C), FOLFIRI was administered. Primary objective of the Phase I part was to determine safety and tolerability, the maximum tolerated dose and pharmacokinetics of the combination. Results: 17 pts (median age 61 yrs; 12 males; 11 ECOG 0; 6 ECOG 1; median therapy line 2 [2-6]) were enrolled in 4 dose levels of resminostat 200, 400, 600 mg QD (3 pts each) and 400 mg BID (6 pts) plus FOLFIRI. Two pts discontinued in C1 and were replaced. No DLT occurred. AEs consisted mainly of GI symptoms of mild and moderate intensity (nausea, vomiting and diarrhea) leading to decreased electrolyte plasma levels in some pts. In the highest dose level tested (400 mg BID) hematological toxicity, mainly neutropenia up to grade 4, was observed leading to dose reductions in 3 pts in C3 and C7. No objective responses were reported, however some pts showed SD for prolonged time (up to 32 w). Results of the completed phase I part will be reported. Conclusions: The combination of resminostat with standard FOLFIRI was safe and well tolerated warranting continuation into the Phase II part of the study. Clinical trial information: NCT01277406.

Abstract The application of palladium‐ and copper‐catalyzed reactions for the aromatic amination of pharmacologically relevant scaffolds is investigated. The focus is set on the scope of several protocols for the introduction of amines of broad structural diversity, allowing for the synthesis of numerous derivatives of one biological hit structure for screening in biological assay systems. Thus, attaining optimized yields and TONs had not a major priority, most important were practical aspects, that is no further purification and drying of reagents and solvents had to be envisaged, ideally only a few transition metal‐based protocols had to be applied for synthesizing structurally diverse compounds in sufficient amounts (several milligrams) for screening without any fine‐tuning of conditions and catalytic systems.