Marco A. Arap

Fingerprinting the circulating repertoire of antibodies from cancer patients

Recognition of molecular diversity in disease is required for the development of targeted therapies. We have developed a screening method based on phage display to select peptides recognized by the repertoire of circulating tumor-associated antibodies. Here we isolated peptides recognized by antibodies purified from the serum of prostate cancer patients. We identified a consensus motif, NXS/TDKS/T, that bound selectively to circulating antibodies from cancer patients over control antibodies from blood donors. We validated this motif by showing that positive serum reactivity to the peptide was specifically linked to disease progression and to shorter survival in a large patient population. Moreover, we identified the corresponding protein eliciting the immune response. Finally, we showed a strong and specific positive correlation between serum reactivity to the tumor antigen, development of metastatic androgen-independent disease, and shorter overall survival. Exploiting the differential humoral response to cancer through such an approach may identify molecular markers and targets for diagnostic and therapeutic intervention.

Aminopeptidase A is a functional target in angiogenic blood vessels

We show that a membrane-associated protease, aminopeptidase A (APA), is upregulated and enzymatically active in blood vessels of human tumors. To gain mechanistic insight, we evaluated angiogenesis in APA null mice. We found that, although these mice develop normally, they fail to mount the expected angiogenic response to hypoxia or growth factors. We then isolated peptide inhibitors of APA from a peptide library and show that they specifically bind to and inhibit APA, suppress migration and proliferation of endothelial cells, inhibit angiogenesis, and home to tumor blood vessels. Finally, we successfully treated tumor-bearing mice with APA binding peptides or anti-APA blocking monoclonal antibodies. These data show that APA is a regulator of blood vessel formation, and can serve as a functional vascular target.

Phage display technology: applications and innovations

The expression of exogenous peptides on the surface of filamentous bacteriophage was initially described by Smith in 1985. Since his first study, different molecules such as small peptides and antibodies have been displayed on coat proteins of phage, greatly expanding the applications of the technology. The past decade has seen considerable progress in the techniques and applications of phage libraries. In addition, different screening methods have allowed isolation and characterization of peptides binding to several molecules in vitro, in the context of living cells, in animals and in humans. Here we review the applications, recent innovations, and future directions of phage display technology.

Augmentation cystoplasty in renal transplantation: A good and safe option: Experience with 25 cases

OBJECTIVES To assess the surgical and long-term results of renal transplantation in 25 patients with bladder dysfunction and augmentation cystoplasty. METHODS We retrospectively reviewed the evolution and surgical outcome of 25 renal transplants in 24 recipients with augmentation cystoplasty. The mean patient age at transplantation was 27.6 years. The etiology of bladder dysfunction was neurogenic bladder with detrusor hyperreflexia (11 patients), tuberculosis (5 patients), vesicoureteral reflux (4 patients), posterior urethral valves (3 patients), and interstitial cystitis (1 patient). Seventeen transplants were from living donors. Augmentation cystoplasty was performed before transplantation in 21 patients. The bowel segments used in the augmentation cystoplasty included ileum in 16, ileocecal segments in 2, and sigmoid in 5 patients. The donor ureter was anastomosed to the native bladder in 16 patients, to the bowel segment in 6, and to the native ureter in 3. RESULTS Twenty kidneys (80%) were functioning at a mean follow-up of 53.2 months (range 6 to 118). The mean serum creatinine was 1.56 mg/dL (range 0.7 to 2.6). Three patients died of unrelated causes and 1 of adenocarcinoma that originated at the vesicointestinal anastomosis. The actuarial graft survival at 1, 2, and 5 years was 96%, 92%, and 78%, respectively. Complications included symptomatic urinary infection, ureteral stenosis, and lymphocele. CONCLUSIONS Augmentation cystoplasty is a safe and effective method to restore function in noncompliant bladders. Renal transplantation can be performed safely after augmentation cystoplasty.

An unrecognized extracellular function for an intracellular adapter protein released from the cytoplasm into the tumor microenvironment

Mammalian cell membranes provide an interface between the intracellular and extracellular compartments. It is currently thought that cytoplasmic signaling adapter proteins play no functional role within the extracellular tumor environment. Here, by selecting combinatorial random peptide libraries in tumor-bearing mice, we uncovered a direct, specific, and functional interaction between CRKL, an adapter protein [with Src homology 2 (SH2)- and SH3-containing domains], and the plexin-semaphorin-integrin domain of β1 integrin in the extracellular milieu. Through assays in vitro, in cellulo, and in vivo, we show that this unconventional and as yet unrecognized protein–protein interaction between a regulatory integrin domain (rather than a ligand-binding one) and an intracellular adapter (acting outside of the cells) triggers an alternative integrin-mediated cascade for cell growth and survival. Based on these data, here we propose that a secreted form of the SH3/SH2 adaptor protein CRKL may act as a growth-promoting factor driving tumorigenesis and may lead to the development of cancer therapeutics targeting secreted CRKL.

Splenogonadal fusion and testicular cancer: case report and review of the literature

A 36 year-old man after tests for assessing male infertility was diagnosed with primary infertility, bilateral cryptorchidism, nonobstructive azoospermia and discontinuous splenogonadal fusion. Carcinoma in situ was found in his left testicle, which was intraabdominal and associated with splenogonadal fusion. To our knowledge, this is the fourth case of splenogonadal fusion associated with testicular cancer reported. One should always bear in mind the possibility of this association for the left cryptorchid testicle.

Schistosomal myelopathy: urologic manifestations and urodynamic findings

OBJECTIVES To describe the clinical and urodynamic features of patients with voiding dysfunction secondary to schistosomal myelopathy. Schistosomiasis mansoni is an endemic fluke infection in South America, the Caribbean, and Africa. In the United States and Europe, people may be infected mainly through travel to endemic areas and immigration of infected individuals. Clinical involvement of the spinal cord is a well-recognized complication of the disease. The typical manifestations are those of an acute transverse myelitis, with sudden onset of lower extremity neuropathy associated with bladder and bowel dysfunction. METHODS We reviewed the records and urodynamic studies of 14 consecutive patients (10 men and 4 women, age range 23 to 49 years) with schistosomal myelopathy confirmed by cerebrospinal fluid serology for S. mansoni, who were referred for evaluation of voiding dysfunction during a 2-year period. At the time of the urologic evaluation, 9 patients had chronic neurologic and urinary symptoms and 5 had recent onset of acute symptoms. The voiding function history, urologic complications, and outcomes after therapy for schistosomiasis were reviewed. RESULTS Of the patients with acute disease (5 patients), the urologic symptoms included urinary retention (3 patients) and incontinence (2 patients). Three of them had concurrent lower back pain and lower limb neurologic deficits. Urodynamic studies were performed in 3 patients and revealed bladder areflexia in 2 patients and detrusor hyperreflexia with external sphincter dyssynergia in 1 patient. The patients were started on clean intermittent catheterization and received praziquantel and corticosteroids. Three patients had complete resolution of their symptoms, one recovered normal voiding function but the neurologic deficits persisted, and one had no clinical improvement. All patients with chronic schistosomal myelopathy presented with lower limb neurologic deficits of varying degrees and urinary symptoms, including difficulty emptying the bladder (7 patients), urinary incontinence (6 patients), and urgency and frequency (2 patients). Laboratory and radiographic evaluation of patients with chronic disease revealed urinary tract infection in 5 patients, hydronephrosis in 2 patients, and bladder calculi in 2 patients. Urologic management consisted of antibiotics, clean intermittent catheterization, anticholinergic medication, and stone removal, as appropriate. In 1 patient, conservative treatment failed and that patient required ileocystoplasty. CONCLUSIONS Schistosomal myelopathy is a potential cause of severe voiding dysfunction secondary to spinal cord disease. A high index of suspicion is paramount because early medical intervention can abort the progression of neurologic deterioration.

Intravenous misplacement of the nephrostomy catheter following percutaneous nephrostolithotomy: two case reports

and it has remained an important approach for removing kidney stones since its inception. A nephrostomy tube is routinely positioned in the renal pelvis in order to tamponade bleeding and drain the collecting system. Although PCNL is an established procedure, major complication rates of up to 7% have been reported.

Targeted molecular-genetic imaging and ligand-directed therapy in aggressive variant prostate cancer

Significance Aggressive variant prostate cancer (AVPC) is a clinically defined tumor with neuroendocrine or small-cell differentiation, visceral metastases, low prostate-specific antigen, androgen receptor insensitivity, and poor/brief responses to androgen-deprivation or platinum-based chemotherapy. AVPC incidence has markedly increased, yielding an unmet diagnostic/therapeutic need. Here we adapted a patient-derived xenograft model and tumor samples to demonstrate ligand-directed theranostics of AVPC in vivo. We engineered human Herpes simplex virus thymidine kinase type-1 as a noninvasive imaging reporter/suicide transgene into adeno-associated virus/phage (AAVP) particles displaying motif ligands to cell surface-associated glucose-regulated protein 78kD (GRP78), toward a clinic-ready system. Although individual components of the AAVP system have been extensively investigated, this study is evidence of successful application in relevant preclinical models of untreatable and hard to diagnose aggressive tumor variants. Aggressive variant prostate cancers (AVPC) are a clinically defined group of tumors of heterogeneous morphologies, characterized by poor patient survival and for which limited diagnostic and treatment options are currently available. We show that the cell surface 78-kDa glucose-regulated protein (GRP78), a receptor that binds to phage-display-selected ligands, such as the SNTRVAP motif, is a candidate target in AVPC. We report the presence and accessibility of this receptor in clinical specimens from index patients. We also demonstrate that human AVPC cells displaying GRP78 on their surface could be effectively targeted both in vitro and in vivo by SNTRVAP, which also enabled specific delivery of siRNA species to tumor xenografts in mice. Finally, we evaluated ligand-directed strategies based on SNTRVAP-displaying adeno-associated virus/phage (AAVP) particles in mice bearing MDA-PCa-118b, a patient-derived xenograft (PDX) of castration-resistant prostate cancer bone metastasis that we exploited as a model of AVPC. For theranostic (a merging of the terms therapeutic and diagnostic) studies, GRP78-targeting AAVP particles served to deliver the human Herpes simplex virus thymidine kinase type-1 (HSVtk) gene, which has a dual function as a molecular-genetic sensor/reporter and a cell suicide-inducing transgene. We observed specific and simultaneous PET imaging and treatment of tumors in this preclinical model of AVPC. Our findings demonstrate the feasibility of GPR78-targeting, ligand-directed theranostics for translational applications in AVPC.

Testosterone deficiency increases hospital readmission and mortality rates in male patients with heart failure.

Background Testosterone deficiency in patients with heart failure (HF) is associated with decreased exercise capacity and mortality; however, its impact on hospital readmission rate is uncertain. Furthermore, the relationship between testosterone deficiency and sympathetic activation is unknown. Objective We investigated the role of testosterone level on hospital readmission and mortality rates as well as sympathetic nerve activity in patients with HF. Methods Total testosterone (TT) and free testosterone (FT) were measured in 110 hospitalized male patients with a left ventricular ejection fraction < 45% and New York Heart Association classification IV. The patients were placed into low testosterone (LT; n = 66) and normal testosterone (NT; n = 44) groups. Hypogonadism was defined as TT < 300 ng/dL and FT < 131 pmol/L. Muscle sympathetic nerve activity (MSNA) was recorded by microneurography in a subpopulation of 27 patients. Results Length of hospital stay was longer in the LT group compared to in the NT group (37 ± 4 vs. 25 ± 4 days; p = 0.008). Similarly, the cumulative hazard of readmission within 1 year was greater in the LT group compared to in the NT group (44% vs. 22%, p = 0.001). In the single-predictor analysis, TT (hazard ratio [HR], 2.77; 95% confidence interval [CI], 1.58–4.85; p = 0.02) predicted hospital readmission within 90 days. In addition, TT (HR, 4.65; 95% CI, 2.67–8.10; p = 0.009) and readmission within 90 days (HR, 3.27; 95% CI, 1.23–8.69; p = 0.02) predicted increased mortality. Neurohumoral activation, as estimated by MSNA, was significantly higher in the LT group compared to in the NT group (65 ± 3 vs. 51 ± 4 bursts/100 heart beats; p < 0.001). Conclusion These results support the concept that LT is an independent risk factor for hospital readmission within 90 days and increased mortality in patients with HF. Furthermore, increased MSNA was observed in patients with LT.