Type 2 diabetes mellitus/obesity drugs: A neurodegenerative disorders savior or a bridge too far?

Glucagon-like peptide-1 (GLP-1) receptor agonist-based drugs (incretin mimetics) have meaningfully impacted current treatment of type 2 diabetes mellitus (T2DM), and their actions on satiety and weight loss have led to their use as an obesity medication. With multiple pleotropic actions beyond their insulinotropic and weight loss ones, including anti-inflammatory and anti-insulin-resistant effects selectively mediated by their receptors present within numerous organs, this drug class offers potential efficacy for an increasing number of systemic and neurological disorders whose current treatment is inadequate. Among these are a host of neurodegenerative disorders that are prevalent in the elderly, such as Parkinson's and Alzheimer's disease, which have bucked previous therapeutic approaches. An increasing preclinical, clinical, and epidemiological literature suggests that select incretin mimetics may provide an effective treatment strategy, but 'which ones' for 'which disorders' and 'when' remain key open questions.

Sitagliptin elevates plasma and CSF incretin levels following oral administration to nonhuman primates: relevance for neurodegenerative disorders.

The endogenous incretins glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP) possess neurotrophic, neuroprotective, and anti-neuroinflammatory actions. The dipeptidyl peptidase 4 (DPP-4) inhibitor sitagliptin reduces degradation of endogenous GLP-1 and GIP, and, thereby, extends the circulation of these protective peptides. The current nonhuman primate (NHP) study evaluates whether human translational sitagliptin doses can elevate systemic and central nervous system (CNS) levels of GLP-1/GIP in naive, non-lesioned NHPs, in line with our prior rodent studies that demonstrated sitagliptin efficacy in preclinical models of Parkinson's disease (PD). PD is an age-associated neurodegenerative disorder whose current treatment is inadequate. Repositioning of the well-tolerated and efficacious diabetes drug sitagliptin provides a rapid approach to add to the therapeutic armamentarium for PD. The pharmacokinetics and pharmacodynamics of 3 oral sitagliptin doses (5, 20, and 100 mg/kg), equivalent to the routine clinical dose, a tolerated higher clinical dose and a maximal dose in monkey, were evaluated. Peak plasma sitagliptin levels were aligned both with prior reports in humans administered equivalent doses and with those in rodents demonstrating reduction of PD associated neurodegeneration. Although CNS uptake of sitagliptin was low (cerebrospinal fluid (CSF)/plasma ratio 0.01), both plasma and CSF concentrations of GLP-1/GIP were elevated in line with efficacy in prior rodent PD studies. Additional cellular studies evaluating human SH-SY5Y and primary rat ventral mesencephalic cultures challenged with 6-hydroxydopamine, established cellular models of PD, demonstrated that joint treatment with GLP-1 + GIP mitigated cell death, particularly when combined with DPP-4 inhibition to maintain incretin levels. In conclusion, this study provides a supportive translational step towards the clinical evaluation of sitagliptin in PD and other neurodegenerative disorders for which aging, similarly, is the greatest risk factor.

A New Generation of IMiDs as Treatments for Neuroinflammatory and Neurodegenerative Disorders.

The immunomodulatory imide drug (IMiD) class, which includes the founding drug member thalidomide and later generation drugs, lenalidomide and pomalidomide, has dramatically improved the clinical treatment of specific cancers, such as multiple myeloma, and it combines potent anticancer and anti-inflammatory actions. These actions, in large part, are mediated by IMiD binding to the human protein cereblon that forms a critical component of the E3 ubiquitin ligase complex. This complex ubiquitinates and thereby regulates the levels of multiple endogenous proteins. However, IMiD-cereblon binding modifies cereblon's normal targeted protein degradation towards a new set of neosubstrates that underlies the favorable pharmacological action of classical IMiDs, but also their adverse actions-in particular, their teratogenicity. The ability of classical IMiDs to reduce the synthesis of key proinflammatory cytokines, especially TNF-α levels, makes them potentially valuable to reposition as drugs to mitigate inflammatory-associated conditions and, particularly, neurological disorders driven by an excessive neuroinflammatory element, as occurs in traumatic brain injury, Alzheimer's and Parkinson's diseases, and ischemic stroke. The teratogenic and anticancer actions of classical IMiDs are substantial liabilities for effective drugs in these disorders and can theoretically be dialed out of the drug class. We review a select series of novel IMiDs designed to avoid binding with human cereblon and/or evade degradation of downstream neosubstrates considered to underpin the adverse actions of thalidomide-like drugs. These novel non-classical IMiDs hold potential as new medications for erythema nodosum leprosum (ENL), a painful inflammatory skin condition associated with Hansen's disease for which thalidomide remains widely used, and, in particular, as a new treatment strategy for neurodegenerative disorders in which neuroinflammation is a key component.

Evaluation of the Pediatric Neuro-Oncology Resources Available in Chile.

PURPOSE: Pediatric neuro-oncology resources are mostly unknown in Chile. We report the human and material resources available in Chilean hospitals providing pediatric neuro-oncology services. METHODS: A cross-sectional survey was distributed to 17 hospitals providing pediatric neuro-oncology services (Programa Infantil Nacional de Drogas Antineoplásicas [PINDA] hospitals, 11; private, 6). RESULTS: Response rate was 71% (PINDA, 8; private, 4). Pediatric neuro-oncology services were mainly provided within general hospitals (67%). Registries for pediatric CNS tumors and chemotherapy-related toxicities were available in 100% and 67% of hospitals, respectively. CNS tumors were treated by pediatric oncologists in 92% of hospitals; none were formally trained in neuro-oncology. The most used treatment protocols were the national PINDA protocols. All WHO essential medicines for childhood cancer were available in more than 80% of the hospitals except for gemcitabine, oxaliplatin, paclitaxel, and procarbazine. The median number of pediatric neurosurgeons per hospital was two (range, 2-6). General neuroradiologists were available in 83% of the centers. Pathology specimens were sent to neuropathologists (58%), adult pathologists (25%), and pediatric pathologists (17%). Intensity-modulated radiotherapy, conformal radiotherapy, and cobalt radiotherapy were used by 67%, 58%, and 42% of hospitals, respectively. Only one private hospital performed autologous hematopoietic cell transplant for children with CNS tumors. CONCLUSION: A wide range of up-to-date treatment modalities are available for children with CNS tumors. Our survey highlights future directions to improve the pediatric neuro-oncology services available in Chile such as the expansion of multidisciplinary clinics, palliative care services, long-term cancer survivorship programs, dedicated clinical research support teams, establishing standardized mechanism for sending pathologic specimen for second opinion to international specialized centers, and establishing specialized neuro-oncology training program.

Treatment of Nonmetastatic Unilateral Retinoblastoma in Children.

Importance: Multi-institutional collaborative studies that include large patient populations for the management of retinoblastoma with histopathological risk factors could provide important information for patient management. Objective: To evaluate the implementation of a strategy for the management of nonmetastatic unilateral retinoblastoma in children based on standardized diagnostic and treatment criteria. Design, Setting, and Participants: This single-arm prospective study applied a strategy based on a single-center experience. The setting was a multicenter study in Latin America (Grupo de America Latina de Oncologia Pediatrica [GALOP]). Participants were children with nonmetastatic unilateral retinoblastoma (staged with the International Retinoblastoma Staging System). The study opened on July 1, 2008, and closed on December 31, 2014. Follow-up was updated until June 30, 2017. Interventions: Stage 0 patients (without enucleation) were given conservative therapy without a protocol. Stage I patients (with enucleation and no residual tumor) were divided into a high-risk group (retrolaminar invasion and/or scleral invasion) and a low-risk group (all remaining patients). High-risk children received adjuvant chemotherapy with 4 alternating cycles of regimen 1 (cyclophosphamide [65 mg/kg/d] [plus sodium-2-mercaptoethane sulfonate], idarubicin hydrochloride [10 mg/m2/d], and vincristine sulfate [0.05 mg/kg/d]) and 4 cycles of regimen 2 (carboplatin [500 mg/m2/d, days 1 and 2] and etoposide [100 mg/m2/d, days 1-3]). Low-risk children did not receive adjuvant therapy. Children with buphthalmia received neoadjuvant and adjuvant chemotherapy for a total of 8 cycles. Main Outcomes and Measures: Probability of event-free survival (extraocular relapse and death from any cause were considered events). Results: Among 187 children registered in the study, 175 were evaluable (92 [52.5%] female; median age, 22 months; age range, 3-100 months). Forty-two were stage 0 children, 84 were stage I low-risk children, and 42 were stage I high-risk children; there were 7 children in the buphthalmia group. With a median follow-up of 46 months, the 3-year probability of event-free survival was 0.97 (95% CI, 0.94-0.99), and the probability of overall survival was 0.98 (95% CI, 0.94-1.00). Stage 0 patients had no events, stage I low-risk patients had 1 event (orbital relapse treated with second-line therapy), stage I high-risk patients had 2 events (1 central nervous system relapse and 1 death from sepsis), and the buphthalmia group had 1 event (orbital relapse, followed by central nervous relapse and death). Conclusions and Relevance: Adjuvant therapy may be effective for high-risk unilateral retinoblastoma but is toxic, and neoadjuvant chemotherapy for buphthalmus appears feasible.

Prevalence of TPMT and ITPA gene polymorphisms and effect on mercaptopurine dosage in Chilean children with acute lymphoblastic leukemia.

BACKGROUND: Mercaptopurine (6-MP) plays a pivotal role in treatment of childhood acute lymphoblastic leukemia (ALL); however, interindividual variability in toxicity of this drug due to genetic polymorphism in 6-MP metabolizing enzymes has been described. We determined the prevalence of the major genetic polymorphisms in 6-MP metabolizing enzymes in Chilean children with ALL. METHODS: 103 Chilean pediatric patients with a confirmed diagnosis of ALL were enrolled. DNA was isolated from whole blood and genetic polymorphism in thiopurine S-methyltransferase (TPMT) and inosine triphosphate pyrophosphatase (ITPA) coding genes were detected by polymorphism chain reaction-restriction fragment length (PCR-RFLP) assay. RESULTS: The total frequency of variant TPMT alleles was 8%. TPMT*2, TPMT*3A and TPMT*3B alleles were found in 0%, 7%, and 1% of patients, respectively. For ITPA, the frequency of P32T allele was 3%. We did not observe any homozygous variant for TPMT and ITPA alleles. We also analyzed a subgroup of 40 patients who completed the maintenance phase of ALL treatment, and we found that patients carrying a TPMT gene variant allele required a significantly lower median cumulative dosage and median daily dosage of 6-MP than patients carrying wild type alleles. CONCLUSION: TMPT genotyping appears an important tool to further optimize 6-MP treatment design in Chilean patients with ALL.

Cytomegalovirus infection in children undergoing hematopoietic stem cell transplantation in Chile.

BACKGROUND: Cytomegalovirus (CMV) infection remains as an important cause of morbidity and mortality in children undergoing hematopoietic stem cell transplantation (HSCT). Our aim was to assess the incidence, risk factors, and outcome related to CMV infection in children after HSCT in a developing country. METHODS: From October 1, 1999, to December 31, 2005, we prospectively studied all patients admitted to the HSCT unit at Hospital Luis Calvo Mackenna in Santiago, Chile. Serologic studies before transplantation and weekly CMV infection surveillance (antigenemia or quantitative PCR) were routinely obtained. Patients with positive antigenemia or quantitative PCR received pre-emptive therapy with ganciclovir, and cases of unfavorable clinical evolution, persistent positive antigenemia, or quantitative PCR after 14 days of ganciclovir were treated with foscarnet. RESULTS: Ninety-seven patients received HSCT. Their median age was 8 years (range, 3 months to 24 years) and their overall survival was 67%. CMV reactivation was diagnosed in 26 patients. Of these, three developed CMV disease (two interstitial pneumonia, one hemorrhagic cystitis). One of the patients with pneumonia died. Risk factors identified were pre-transplant serologic status (positive recipient), acute and chronic graft versus host disease (GvHD), GvHD prophylaxis, and treatment with antithymocyte globulin. CONCLUSIONS: The rate and prognosis of CMV infection among children treated at our HSCT unit is similar to those reported from industrialized countries. These findings reflect adequate prevention and management of CMV infection within our program.