Abstract A244: Characterization of a novel potent and selective CDK4/6 inhibitor and a resistance mechanism

CDK4 and CDK6 are two highly related cyclin D-dependent cell cycle regulatory kinases. CDK4/6 activity promotes G1 to S phase transition by phosphorylating the retinoblastoma (Rb) tumor suppressor protein. Here, we report the characterization of a potent, selective and orally-available small molecule inhibitor of CDK4/6 for treating Rb-positive cancer. The inhibitor was over 1000-fold more potent in inhibiting CDK4 than CDK1. It also showed Rb-dependent anti-proliferative activity both in cancer cell lines and in xenograft tumor models. A greater degree of variation in sensitivity to the inhibitor was observed in colon cancer cell lines compared to the other cell lines tested. To understand this difference in sensitivity, we isolated CDK4/6 inhibitor-resistant colon cancer cells by growing sensitive cells in the presence of the inhibitor. Gene expression in the parental and the resistant cells was analyzed and compared. Cyclin E1, a CDK2 cyclin, was found to be the most significantly overexpressed gene in the resistant cells. Consistent with this, CDK2-associated cyclin E1 protein and CDK2 kinase activity were also significantly increased in the cells. These results suggest that high expression of cyclin E1 may make tumors less sensitive to CDK4/6 inhibition and could be a potential sensitivity marker for patient selection for treatment with a CDK4/6 inhibitor.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2011 Nov 12-16; San Francisco, CA. Philadelphia (PA): AACR; Mol Cancer Ther 2011;10(11 Suppl):Abstract nr A244.

Outcome of renal transplantation in adult patients with augmented bladders

OBJECTIVE

We studied the long-term renal graft functions, survivals, and complications among patients with augmented bladders.

PATIENTS AND METHODS

Between 1976 and 2008, we performed 6/2600 renal transplantations in patients with augmented bladders. The mean patient age was 52 years. The cause of end-stage renal disease was chronic interstitial kidney disease in all patients, being secondary to lower urinary tract dysfunction. The etiology of bladder dysfunction was tuberculosis in 4 cases, bladder exstrophy in 1, and myelomeningocele in 1. Enterocystoplasty had been performed at a mean of 19 years prior to transplantation. The ureter was implanted into the native ureter in 5 cases and the bowel segment in 1 case.

RESULTS

With a mean follow-up of 56 months (range, 20-100 months), the overall graft survival was 50%. Three grafts were lost due to venous thrombosis (n = 1), and chronic allograft nephropathy (n = 2) at 37 and 100 months posttransplantation. No patient died during follow-up. Mean serum creatinine was 1.44 mg/dL with Modification of Diet in Renal Disease (MDRD) clearance of 76 mL/min/1.73 m(2). One fistula that caused obstructive uropathy and 2 cases of migration of a double J catheter were among the surgical complications. These patients showed a mean of 7 episodes of uncomplicated urinary infections. Only 1 patient was rehospitalized due to a complicated urinary tract infection.

CONCLUSIONS

Patients with enterocystoplasty and renal transplantation show a greater risk of urinary tract infections, albeit mostly uncomplicated. Despite this, the long-term results are acceptable.

Tetrahydroquinoline derivatives as CRTH2 antagonists

A series of tetrahydroquinoline-derived inhibitors of the CRTH2 receptor was discovered by a high throughput screen. Optimization of these compounds for potency and pharmacokinetic properties led to the discovery of potent and orally bioavailable CRTH2 antagonists.

Discovery and optimization of CRTH2 and DP dual antagonists

A series of phenylacetic acid derivatives was discovered as CRTH2 antagonists. Modification of the series led to compounds that are also antagonists of DP. Since activation of CRTH2 and DP are believed to play key roles in mediating responses of asthma and other immune diseases, this series was optimized to increase the dual antagonistic activities and improve pharmacokinetic properties. These efforts led to selection of AMG 009 as a clinical candidate.

Review article: pharmacological therapy for hepatocellular carcinoma with sorafenib and other oral agents

BACKGROUND

Hepatocellular carcinoma (HCC) is the fifth most common malignancy worldwide. Unresectable disease patients have median survival of few months. There is a substantial need for novel treatments for patients with advanced HCC.

AIM

To provide an update review of mechanism of hepatocarcinigenesis and systemic therapies for HCC and the relevant role of Sorafenib in patients with advanced disease.

METHODS

A Medline search was performed to identify pertinent original research and review articles. Selected references in these articles were also evaluated.

RESULTS

Systemic chemotherapy for HCC has been quite ineffective. Preclinical studies demonstrated that Raf/MAPK-ERK kinase (MEK)/Extracellular signal regulated kinase (ERK) pathway has a role in HCC. HCC tumours are highly vascularized and vascular endothelial growth factor (VEGF) augments HCC development and metastasis. Sorafenib blocks tumour cell proliferation by targeting Raf/MEK/ERK signalling and exerts an antiangiogenic effect by targeting VEGF receptors-2/3 and platelet derived growth factor receptor beta tyrosine kinases.

CONCLUSIONS

Currently available therapies are not effective for patients with advanced HCC. Sorafenib has demonstrated for the first time to prolong survival in patients with advanced HCC, and it is the new reference standard for systemic treatment in these patients.

[The upper limb of children with cerebral palsy: surgical aspects]

Cerebral palsy has a complex and multifactorial etiology. The management of the upper limb aims to improve function, hygiene and cosmesis in many patients. Surgical treatment need a good and repeated clinical examination before. The functional surgery has a lot of procedures on the elbow, the wrist, the fingers and the thumb. These procedures include the release or lengthening of spastic muscles, tendon transfers and joint stabilizations. The surgeon must know the indications and contraindications of functional surgery.