Clinical efficacy of tadalafil compared to sildenafil in treatment of moderate to severe canine pulmonary hypertension: a pilot study

INTRODUCTION

Canine pulmonary hypertension (PH) is associated with high morbidity and mortality. Tadalafil, a phosphodiesterase-5 inhibitor used commonly in humans with PH, has not been evaluated in a clinical trial in dogs with naturally occurring PH. Our objectives were to compare the efficacy of tadalafil and sildenafil on PH assessed by peak tricuspid regurgitant flow velocity, estimated systolic pulmonary arterial pressure gradient, voluntary activity, quality of life, and safety profiles in dogs with moderate to severe PH.

ANIMALS

Twenty-three dogs with echocardiographic evidence of moderate to severe PH were enrolled.

METHODS

A prospective short-term, randomized, double-blinded pilot study was carried out. Dogs with PH were randomly allocated to receive sildenafil or tadalafil for 2 weeks and assessed via echocardiography, activity monitors, and owner-reported outcomes.

RESULTS

Collectively, phosphodiesterase-5 inhibition significantly decreased (improved) quality of life scores (p = 0.003) and visual analog score (p = 0.024) without significant between-treatment difference of these variables. Phosphodiesterase-5 inhibition did not significantly affect peak tricuspid regurgitant flow velocity (p = 0.056) or voluntary activity (p = 0.27). A total of 33% (7/21) of dogs experienced at least one adverse event during the study (tadalafil, n = 5; sildenafil, n = 2) with no significant difference between treatment type and incidence of adverse events (p = 0.36).

DISCUSSION

In this pilot study, phosphodiesterase-5 inhibition led to apparent improvement in quality of life scores without documenting superiority of tadalafil over sildenafil.

CONCLUSION

Tadalafil at a dose of 2 mg/kg once daily appears to be a viable alternative to sildenafil in dogs with moderate to severe PH.

Phase I and biomarker study of OPB-51602, a novel signal transducer and activator of transcription (STAT) 3 inhibitor, in patients with refractory solid malignancies

BACKGROUND

The aim of this study was to determine the maximum-tolerated dose (MTD), safety, pharmacokinetics, and pharmacodynamics of OPB-51602, an oral, direct signal transduction activator of transcription 3 (STAT3) inhibitor, in patients with refractory solid tumors.

PATIENTS AND METHODS

Three cohorts were studied: cohort A, a sequential dose escalation of OPB-51602 administered intermittently (days 1-14 every 21 days); cohort B, an expansion cohort evaluating the dose lower than the MTD; cohort C, evaluating continuous daily dosing.

RESULTS

Fifty-one patients were studied at 2, 4, and 5 mg per day dosing. The MTD was 5 mg; first-cycle dose-limiting toxicities (DLTs) were grade 3 hyponatremia in one patient, and grade 3 dehydration in another. Intermittent dosing of both 2 and 4 mg doses were tolerable, and the recommended phase II dose was 4 mg. Cohort B investigated 4 mg intermittently, whereas cohort C investigated 4 mg continuously. Common toxicities included fatigue, nausea/vomiting, diarrhea, anorexia, and early-onset peripheral neuropathy. Drug-induced pneumonitis occurred in two patients in cohort C. Continuous dosing was associated with a higher incidence of peripheral neuropathy and a lower mean relative dose intensity, compared with intermittent dosing. Steady-state pharmacokinetics was characterized by high oral clearance, mean elimination half-life ranging from 44 to 61 h, and a large terminal-phase volume of distribution. An active metabolite, OPB-51822, accumulated to a greater extent than OPB-51602. Flow cytometry of peripheral blood mononuclear cells demonstrated pSTAT3 (Tyr(705)) inhibition following exposure. Two patients achieved partial responses at 5 mg intermittently and 4 mg continuously; both had epidermal growth factor receptor (EGFR) mutation-positive non-small-cell lung cancer (NSCLC) with prior EGFR tyrosine kinase inhibitor exposure.

CONCLUSION

OPB-51602 demonstrates promising antitumor activity, particularly in NSCLC. Its long half-life and poorer tolerability of continuous dosing, compared with intermittent dosing, suggest that less frequent dosing should be explored.

CLINICALTRIALSGOV IDENTIFIER

NCT01184807.

Effects on superconductivity of transition-metal doping in FeSe(0.5)Te(0.5)

We investigate superconductivity in the compound FeSe(0.5)Te(0.5) and in its transition-metal-substituted derivatives Fe(1-x)TM(x)Se(0.5)Te(0.5), where x = 5% and the substituent ions studied were Mn, Co, Ni, Cu and Zn. Electronic and magnetic measurements indicate that doping with Mn or by Co acts respectively to cause a slight enhancement or suppression of the transition temperature. However, doping with this concentration of Ni or Cu destroys the superconductivity completely, and leads to semiconducting behaviour. Zn ions cannot be incorporated properly into the parent compound. The reasons for these contrasting effects are associated with the differing magnetic properties of the substituent ions, which determine their local impurity moments and the net carrier concentrations in the doped 11 system. The effects of magnetic ion substitution on superconductivity suggest that the pairing symmetry may not be either pure s wave or pure d wave.

Generation of PCR-based DNA fragments for specific detection of Streptomyces saraceticus N45

Streptomyces saraceticus strain N45, a saprophytic Gram-positive bacteria, has been shown to harbor high chitinase activity. Due to its potential use in biological control, the cloning of chitinase genes and the development of methods to quickly and precisely detect its presence have become necessary. In this study, PCR-based random amplified polymorphic DNA (RAPD) and PCR strategies were used to amplify random DNA fragments from the genome of S. saraceticus N45. Three amplified DNA fragments, 417, 523 and 655 bp in length, were further isolated, subcloned and sequenced. Nest primers were designed from terminal ends of these three fragments and used for further PCR reactions. A single specific band was produced from the genomic DNA of S. saraceticus N45 for each nest primer pair. These three single bands were S. saraceticus N45 specific and were not amplified from other species of Streptomyces or bacteria, such as Ralstonia solanacearum, Agrobacterium tumefaciens, E. coli, Bacillus subtilis and Xanthomonas campestris pv. campestris. Through detection of the coexistence of these three fragments in PCR reaction using DNA or bacterial cells directly, the presence of S. saraceticus N45 can be confirmed. Further Southern analysis indicated that these three DNA fragments were specifically present in the S. saraceticus N45 genome in a single copy manner, and therefore, that they can potentially be used as markers for identification of S. saraceticus N45.

Long term follow-up and late complications of 2-chlorodeoxyadenosine in previously treated, advanced, indolent non-Hodgkin's lymphoma

BACKGROUND

The aim of this study was to determine the long term outcome and toxicities after the administration of 2-chlorodeoxyadenosine (2-CdA) to patients with previously treated, advanced, indolent non-Hodgkin's lymphoma (NHL).

METHODS

Twenty-two patients (median age, 55 years) with relapsed or refractory low grade NHL (median disease duration, 2.8 years) were treated with 2-CdA by continuous infusion at 0.1 mg/kg/day over 5 or 7 days every 28 days, for a maximum of 6 cycles.

RESULTS

The overall response rate was 45%. Two patients (9%) achieved a complete response (CR), 8 patients (36%) achieved a partial response, and 12 patients (55%) had no response. The two patients achieving CR have remained in CR for 46 and 38 months, respectively. Freedom from treatment failure at 24 months was 32%. Overall survival at 24 months was 59%. Three patients developed second malignancies: acute myelogenous leukemia (AML), myelodysplastic syndrome, and a cutaneous lymphoproliferative disorder. Fourteen patients have died after a median follow-up of 28 months (range, 3.9-49.2 months) due to progressive NHL (11 patients), infection (2 patients), and AML (1 patient).

CONCLUSIONS

2-CdA is an active agent for patients with previously treated, advanced, indolent NHL and may result in lasting remissions. Late complications following treatment may include delayed bacterial, fungal, or viral infection. Determination of whether the second malignancies that occurred in three patients reported herein were related to treatment with 2-CdA will require further study.

2-Chlorodeoxyadenosine in cutaneous T-cell lymphoproliferative disorders

The efficacy and toxicity of 2-chlorodeoxyadenosine (2-CdA) in cutaneous T-cell lymphoproliferative disorders was examined. Between February 1991 and April 1996, 25 patients with relapsed or refractory cutaneous T-cell lymphoproliferative disorders (24 mycosis fungoides or Sezary syndrome, one Ki-1+ anaplastic large cell lymphoma) were treated with 2-CdA initially administered by continuous intravenous infusion at a dose of 0.1 mg/kg/d for 7 days (13 patients). The infusion duration was subsequently reduced to 5 days (9 patients) because of prohibitive hematologic toxicity. Three patients were treated at the same daily dose by bolus injection over two hours for 5 days. Cycles were administered at 28 day intervals. Seventeen patients received more than one cycle. An overall response rate of 24% was achieved. Three patients (12%) had a complete response with a median duration of 4.5 months (range, 2.5 to 16). Three (12%) had a partial response with a median duration of 2 months (range, 2 to 4). Nineteen patients (76%) had no response. The most significant toxicities encountered were myelosuppression (64%) and infectious complications (64%). 2-CdA has activity as a single agent in patients with previously treated relapsed T-cell lymphoproliferative disorders.