Retinal transduction profiles by high-capacity viral vectors

Retinal gene therapy with adeno-associated viral (AAV) vectors is safe and effective in humans. However, the limited cargo capacity of AAV prevents their use for therapy of those inherited retinopathies (IRs) due to mutations in large (>5kb) genes. Viral vectors derived from Adenovirus (Ad), Lentivirus (LV) and Herpesvirus (HV) can package large DNA sequences but do not target efficiently retinal photoreceptors (PRs) where the majority of genes responsible for IRs are expressed.

Here, we have evaluated the mouse retinal transduction profiles of vectors derived from 16 different Ad serotypes, 7 LV pseudotypes, and from a bovine HV. Most of the vectors tested transduced efficiently the retinal pigment epithelium (RPE). We found that LV-GP64 tends to transduce more PRs than the canonical LV-VSVG albeit this was restricted to a narrow region. We observed more extensive PR transduction with HdAd1, 2 and 5/F35++ than with LV, although none of them outperformed the canonical HdAd5 or matched the extension of PR transduction achieved with AAV2/8.

AAV-mediated photoreceptor transduction of the pig cone-enriched retina

Recent success in clinical trials supports the use of adeno-associated viral (AAV) vectors for gene therapy of retinal diseases caused by defects in the retinal pigment epithelium (RPE). In contrast, evidence of the efficacy of AAV-mediated gene transfer to retinal photoreceptors, the major site of inherited retinal diseases, is less robust. In addition, although AAV-mediated RPE transduction appears efficient, independently of the serotype used and species treated, AAV-mediated photoreceptor gene transfer has not been systematically investigated thus so far in large animal models, which also may allow identifying relevant species-specific differences in AAV-mediated retinal transduction. In the present study, we used the porcine retina, which has a high cone/rod ratio. This feature allows to properly evaluate both cone and rod photoreceptors transduction and compare the transduction characteristics of AAV2/5 and 2/8, the two most efficient AAV vector serotypes for photoreceptor targeting. Here we show that AAV2/5 and 2/8 transduces both RPE and photoreceptors. AAV2/8 infects and transduces photoreceptor more efficiently than AAV2/5, similarly to what we have observed in the murine retina. The use of the photoreceptor-specific rhodopsin promoter restricts transgene expression to porcine rods and cones, and results in photoreceptor transduction levels similar to those obtained with the ubiquitous promoters tested. Finally, immunological, toxicological and biodistribution studies support the safety of AAV subretinal administration to the large porcine retina. The data presented here on AAV-mediated transduction of the cone-enriched porcine retina may affect the development of gene-based therapies for rare and common severe photoreceptor diseases.

Determinants of fetal leptin synthesis, fat mass, and circulating leptin concentrations in well-nourished ewes in late pregnancy

We have investigated the factors regulating leptin synthesis, fat deposition, and circulating leptin concentrations in fetuses of well nourished ewes in late pregnancy. Vascular catheters were surgically inserted in 17 pregnant ewes and their fetuses at 103-120 d gestation (term = 147 +/- 3 d). Ewes were fed a diet providing either 100% (control; n = 9) or approximately 155% (well fed; n = 8) of the maintenance energy requirements and fetal perirenal and interscapular fat depots were collected at 139-141 d gestation. There was a significant relationship between the relative mass of fetal unilocular fat and fetal glucose (relative mass of unilocular fat, 1.14; fetal glucose, +0.16; r = 0.50; P < 0.04; n = 17), but not insulin, concentrations in the control and well-fed groups. In contrast to the controls, there was a positive relationship between the relative abundance of leptin mRNA and fetal insulin, but not glucose, concentrations in fetal perirenal adipose tissue in the well-fed group. A moderate increase in maternal nutrition also resulted in a strong reciprocal relationship between uncoupling protein 1 and leptin expression in fetal perirenal adipose tissue in late gestation (well-fed group: uncoupling protein 1 mRNA:18S rRNA, -0.51; leptin mRNA:beta-actin mRNA, +1.53; r = 0.80; P < 0.02; n = 8). These studies provide evidence that fetal glucose and insulin differentially regulate fetal fat deposition and leptin mRNA expression within the fetal perirenal fat depot in the well nourished animal during late gestation.

Hepatic intra-arterial chemotherapy using a percutaneous catheter in pretreated patients with metastatic colorectal carcinoma

BACKGROUND

Hepatic intra-arterial chemotherapy (HIAC) leads to a higher response rate than systemic administration in untreated patients with liver metastases from colorectal cancer (CRC). The aim of this study was to evaluate the activity and safety of giving HIAC through a percutaneous catheter in pre-treated patients.

PATIENTS AND METHODS

Forty-five CRC patients with liver-only or liver-dominant metastases, resistant or refractory to previous systemic therapy, were treated using a temporary trans-subclavian catheter. A 3-day chemotherapy regimen of daily 5-fluorouracil (5-FU) 1000 mg/m2/day + heparin 5000 IU/day given as a 24-hour continuous infusion, and twice daily bolus injections of cisplatin (CDDP) 10 mg/m2 and mitomycin C (MMC) 2 mg/m2, was administered every six weeks.

RESULTS

One hundred and seventeen courses were administered to 45 patients (a median of three per patient: range 1-5). Of the 44 patients evaluable for response, 16 (35%) had a partial response, 15 (33%) stable disease and 12 (26%) progressive disease. Eleven of the 16 responding patients had been refractory to a previous 5-FU-based systemic therapy. The most relevant grade 3-4 toxicities included neutropenia (22%) and thrombocytopenia (15%). Gastro-duodenal ulcers occurred in nine patients. Catheter displacement was recorded during 22 out of 117 (18%) courses.

CONCLUSION

HIAC with 5-FU, CDDP and MMC given through a temporary percutaneous catheter is safe and active in pretreated patients with metastatic CRC. Iatrogenic gastroduodenal ulcers are a serious but manageable complication.

Phase I study of twelve-day prolonged infusion of high-dose ifosfamide and doxorubicin as first-line chemotherapy in adult patients with advanced soft tissue sarcomas

PURPOSE

To determine whether a prolonged 12-day continuous infusion allows the administration of high-dose ifosfamide (IFO) with an acceptable toxicity profile when combined with full-dose doxorubicin (Adriamycin; ADM) as first-line chemotherapy in patients with advanced soft tissue sarcomas.

PATIENTS AND METHODS

Escalating doses of continuous infusion IFO (8-15 g/m2) given on days 1 to 12 in combination with ADM 75 mg/m2 given on day 8 and prophylactic granulocyte colony-stimulating factor support were administered every 4 weeks to 35 chemonaïve patients with advanced soft tissue sarcomas.

RESULTS

The maximum tolerated dose was IFO 15 g/m2. Hematological toxicity was the main dose-limiting toxicity and was dose dependent. Furthermore, thrombocytopenia was cumulative. Grade 4 (WHO) neutropenia and thrombocytopenia were recorded in 48% and 14% of courses, respectively. Eight patients experienced febrile neutropenia. A partial response was observed in 16 out of 30 assessable patients [53%, 95% confidence interval (CI) 25-63]; median time to progression was 25 weeks (range 4-91).

CONCLUSIONS

This study proved that a prolonged 12-day continuous infusion allows an increase in the total IFO dose that can be safely combined with ADM. A multicentric phase II study by the Italian Sarcoma Group to assess its antitumor activity is currently ongoing in patients with advanced soft tissue sarcomas.

Vinorelbine, cisplatin and continuous infusion of 5-fluorouracil (ViFuP) in metastatic breast cancer patients: a phase II study

PURPOSE

Chemotherapy regimens for patients with advanced breast cancer or large primary tumours (including locally advanced disease) usually contain anthracyclines, taxanes or both. We investigated a multi-agent regimen for patients for whom anthracyclines and/or taxanes may not be suitable. We assessed efficacy in terms of response rate and time to progression of a combination with continuous infusion 5-fluorouracil (5-FU), vinorelbine and cisplatin (ViFuP regimen), as a first or subsequent line treatment for metastatic breast cancer patients.

PATIENTS AND METHODS

One hundred consecutive patients with advanced breast cancer were treated with 5-FU 200 mg/m2 administered continuously through a permanent central venous line; vinorelbine was given on days 1 and 3 at a dose of 20 mg and cisplatin was administered at 60 mg/m2 on day one. Therapy was given every three weeks. The median age was 50 years (range 23-72). Fifty-two patients had received prior chemotherapy for metastatic breast cancer, and sixty-one percent had previously received anthracyclines, thirty-five percent taxanes and twenty-nine percent 5-FU as a bolus injection. All patients were assessable for toxicity, four patients were not assessable for response.

RESULTS

There were four complete responses (4%). Forty-nine patients had a partial response (overall response rate, 55%; 95% confidence interval (CI): 45%-65%). After a median follow-up of 10.2 months, median duration of response is 5.2 months (range 1.5-20.7+ months), time to progression (TTP) is 6.8 months (range 0.3-24.7 months). Acute toxicity, including myelosuppression, was mild: only 18% of patients had grade 4 granulocytopenia and one patient experienced grade 4 diarrhea. Only 15% of patients had any non-hematological grade 3 toxicity including nausea (4%), stomatitis (4%), diarrhea (2%), fatigue (1%), fever (1%), photosensitivity (1%), hand-foot syndrome (1%). Grade 2 alopecia was observed only in six patients (6%). Eleven patients developed a right diaphragmatic supra elevation, while deep vein thrombosis, central venous catheter associated, occurred in eight patients.

CONCLUSIONS

We identified a combination chemotherapy with noteworthy efficacy and well tolerated subjectively as either a first- or second-line treatment for metastatic breast cancer patients. The regimen warrants further development focusing on the comparison with either continuous administration of oral fluoropyrimidine derivatives.

Phase I and pharmacologic study of weekly gemcitabine and paclitaxel in chemo-naïve patients with advanced non-small-cell lung cancer

BACKGROUND

Gemcitabine (GEM) and paclitaxel (TAX) are active, non-cross-resistant drugs in non-small-cell lung cancer (NSCLC). We performed a phase I study to determine the maximum-tolerated dose (MTD), antitumor activity and pharmacokinetics of GEM and TAX given weekly in chemo-naïve patients with advanced NSCLC.

PATIENTS AND METHODS

Escalating doses of GEM (800-2000 mg/m2) and TAX (60-100 mg/m2) were administered on days 1, 8, 15 every 4 weeks to 35 patients with advanced NSCLC. Plasma pharmacokinetics of TAX and GEM was assessed at the three higher dose-levels.

RESULTS

Dose-escalation was discontinued in absence of MTD because of increased cumulative toxicity leading to dose modification or treatment delay at levels 6 and 7 (TAX 100 mg/m2 plus GEM 1750 and, respectively, 2000 mg/m2). Hematological toxicity included grade 4 neutropenia in 3% of cycles, grade 3 thrombocytopenia in one cycle and febrile neutropenia in three cycles. Maximal non-hematological toxicity was grade 3 elevation in serum transaminases and grade 2 neuro-sensory toxicity in 8% and 5% of cycles, respectively. At the two higher dose-levels a non-linear pharmacokinetics of GEM was observed with a remarkable variability of Cmax and AUC. No pharmacokinetic interactions were reported. Objectives responses were seen at all dose levels, with an overall response rate of 43% (95% confidence interval (95% CI): 25.5%-62.6%) in 30 evaluable patients.

CONCLUSIONS

The weekly administration of GEM and TAX is very well tolerated, and has shown promising antitumor activity in NSCLC. In view of the cumulative toxicity and of the pharmacokinetic profile of GEM, doses of 1500 mg/m2 of GEM and 100 mg/m2 of TAX are recommended for phase II studies.