7141 POSTER Phase II Trial of the Oral Multikinase Inhibitor Regorafenib (BAY 73-4506) as First-line Therapy in Patients With Metastatic or Unresectable Renal Cell Carcinoma (RCC)

Discovery of Potent EGFR Inhibitors With 6-Arylureido-4-anilinoquinazoline Derivatives

According to the classical pharmacophore fusion strategy, a series of 6-arylureido-4-anilinoquinazoline derivatives ( Compounds 7a - t ) were designed, synthesized, and biologically evaluated by the standard CCK-8 method and enzyme inhibition assay. Among the title compounds, Compounds 7a , 7c , 7d , 7f , 7i , 7o , 7p , and 7q exhibited promising anti-proliferative bioactivities, especially Compound 7i , which had excellent antitumor activity against the A549, HT-29, and MCF-7 cell lines (IC₅₀ = 2.25, 1.72, and 2.81 μM, respectively) compared with gefitinib, erlotinib, and sorafenib. In addition, the enzyme activity inhibition assay indicated that the synthesized compounds had sub-micromolar inhibitory levels (IC₅₀, 11.66-867.1 nM), which was consistent with the results of the tumor cell line growth inhibition tests. By comparing the binding mechanisms of Compound 7i (17.32 nM), gefitinib (25.42 nM), and erlotinib (33.25 nM) to the EGFR, it was found that Compound 7i could extend into the effective region with a similar action conformation to that of gefitinib and interact with residues L85, D86, and R127, increasing the binding affinity of Compound 7i to the EGFR. Based on the molecular hybridization strategy, 14 compounds with EGFR inhibitory activity were designed and synthesized, and the action mechanism was explored through computational approaches, providing valuable clues for the research of antitumor agents based on EGFR inhibitors.

Design, synthesis and antitumor activity of aromatic urea-quinazolines

Background: Gefitinib and sorafenib have been proved effective for the treatment of cancers in clinical practice for years. Materials & methods: We intended to integrate the structural features of gefitinib and sorafenib and construct structurally unique 7-aromatic ureido-4-anilinoquinazolines. Results: Most of the targets exhibited promising antitumor activities. 8u showed excellent antitumor activities against the three tested cell lines (IC₅₀, 0.81-2.49 μM). The enzymatic, apoptosis assay of 8u were also performed to study their preliminary action of mechanism. Conclusion: 8u deserve further research as antitumor agents.

ABL kinase inhibitory and antiproliferative activity of novel picolinamide based benzothiazoles

A series of novel picolinamide based benzothiazoles (17 final compounds), targeting both wild-type and the most resistant T315I mutant of Bcr-Abl kinase, has been designed and synthesized. Moreover, a selected array (8 compounds) was evaluated for its antiproliferative activity over a panel of 60 cancer cell lines. Compound 5l was the most potent derivative against both native and T315I mutant ABL with IC50 values of 18.2 and 39.9nM, respectively, and showed highly selective inhibitory activity (89.8%) towards the Bcr-Abl dependent leukemia cell (K-562) at 10μM concentration. Significance of C6-oxypicolinamide moiety and SAR study for the C2 aliphatic side chain of benzothiazole are discussed in detail.

Regorafenib: carving a niche in the crowded therapeutic landscape

The oral multikinase inhibitor regorafenib targets both tumor cell proliferation and vasculature and is active in heavily pretreated patients with metastatic colorectal cancer, for which the US FDA granted its approval in September 2012. The benefit for regorafenib was seen in these patients in most prespecified subgroups. The drug is also being used in other tumor types where it has shown exciting potential especially in gastrointestinal stromal tumors. The drug is well tolerated but requires close monitoring during administration. Common side effects include asthenia/tiredness, loss of appetite, hand-foot skin syndrome, diarrhea, mucositis, weight loss, infections, hypertension and rash. Serious adverse events to look out for are liver toxicity, hemorrhage and gastrointestinal perforation. Biomarker data should help us to optimize the use of these drugs to select which patients are most likely to benefit.

Regorafenib in Japanese patients with solid tumors: phase I study of safety, efficacy, and pharmacokinetics

The safety, pharmacokinetics, and antitumor activity of the multikinase inhibitor regorafenib in Japanese patients was assessed in this multicenter, single-arm, phase I trial. Fifteen patients with treatment-refractory advanced solid tumors received regorafenib 160 mg once daily for the first 3 weeks of each 4-week cycle until disease progression, unacceptable toxicity, or investigator or patient decision to stop. The median duration of treatment was 2.1 months (range, 0.9–20.1 months). At data cutoff, one patient was still receiving regorafenib in cycle 21. Reasons for treatment discontinuation were disease progression (n = 12) and adverse events (liver enzyme elevation n = 1; anemia n = 1). Adverse events necessitated dose reduction in six patients, interruption of daily treatment in seven patients, and cycle delay in four patients. All patients experienced at least one drug-related adverse event, particularly gastrointestinal (87 %), dermatologic (73 %), or hematologic (67 %) events. There was no significant change in time to maximum concentration or terminal half-life of regorafenib and its active metabolites M2 and M5 between single dosing and 21-day continuous dosing. The area under the concentration–time curve was 2.1-fold higher for regorafenib, 5.2-fold higher for M2, and 37.3-fold higher for M5, and the maximum concentration was 2.0-fold, 4.8-fold, and 36.0-fold higher, respectively, after continuous dosing than after single dosing. One patient had a partial response (duration 10.5 months) and seven patients had stable disease. This study indicates that regorafenib 160 mg orally once daily (21 days on/7 days off treatment) can be given to Japanese patients who have solid tumors, without undue toxicity.

Regorafenib for cancer

INTRODUCTION

Regorafenib (BAY 73-4506) is a novel, orally active, diphenylurea multikinase inhibitor of VEGFR1-3, c-KIT, TIE-2, PDGFR-β, FGFR-1, RET, RAF-1, BRAF and p38 MAP kinase.

AREAS COVERED

This review covers the preclinical development of regorafenib as well as the pivotal Phase I studies. The safety profile of regorafenib is discussed in context with other oral multikinase inhibitors bearing a similar target profile. Current clinical developments, especially in colorectal cancer (CRC) and gastrointestinal stromal tumor (GIST), are addressed. Open questions on clinically useful biomarkers predicting response with regard to a personalized therapy strategy are also being discussed.

EXPERT OPINION

Regorafenib (BAY 73-4506) is a novel, orally active multikinase inhibitor that is well tolerated in preclinical mouse models as well as clinically according to Phase I - III trials performed. The toxicity profile is comparable with other oral multikinase inhibitors with similar molecular targets. Regorafenib has promising antineoplastic activity in various tumor types. Two large, randomized Phase III pivotal registration studies in patients with GIST and CRC, respectively, already completed enrolment, with final results being awaited. Further extensive clinical development as a single agent or in combination with standard chemotherapeutic agents in various malignant tumors is ongoing. Moreover, regorafenib has recently been granted Orphan Drug Status for GIST tumors and 'fast track' status for both GIST and CRC by the FDA.