Gene Therapy and Apheresis

Gene therapy is becoming a real therapeutic chance in some genetic disorders. The first candidates to this approach are genetic diseases which involve hematopoiesis, because of the facility for the collection and the manipulation of hematopoietic progenitors.

Apheresis techniques, which are able to collect a great number of mononuclear cells from peripheral blood, are ideal for obtaining a large number of cells which can be transfected.

Future uses of gene therapy techniques could be: the treatment of hematopoietic genetic disorders, procedures of gene marking, and the manipulation of normal hematopoietic cells with the objective of increasing their resistance to myelotoxic drugs.

Sirolimus-based graft-versus-host disease prophylaxis promotes the in vivo expansion of regulatory T cells and permits peripheral blood stem cell transplantation from haploidentical donors

Hematopoietic stem cell transplantation (HSCT) from human leukocyte antigen (HLA) haploidentical family donors is a promising therapeutic option for high-risk hematologic malignancies. Here we explored in 121 patients, mostly with advanced stage diseases, a sirolimus-based, calcineurin-inhibitor-free prophylaxis of graft-versus-host disease (GvHD) to allow the infusion of unmanipulated peripheral blood stem cell (PBSC) grafts from partially HLA-matched family donors (TrRaMM study, Eudract 2007-5477-54). Conditioning regimen was based on treosulfan and fludarabine, and GvHD prophylaxis on antithymocyte globulin Fresenius (ATG-F), rituximab and oral administration of sirolimus and mycophenolate. Neutrophil and platelet engraftment occurred in median at 17 and 19 days after HSCT, respectively, and full donor chimerism was documented in patients' bone marrow since the first post-transplant evaluation. T-cell immune reconstitution was rapid, and high frequencies of circulating functional T-regulatory cells (Treg) were documented during sirolimus prophylaxis. Incidence of acute GvHD grade II-IV was 35%, and occurrence and severity correlated negatively with Treg frequency. Chronic GvHD incidence was 47%. At 3 years after HSCT, transpant-related mortality was 31%, relapse incidence 48% and overall survival 25%. In conclusion, GvHD prophylaxis with sirolimus-mycophenolate-ATG-F-rituximab promotes a rapid immune reconstitution skewed toward Tregs, allowing the infusion of unmanipulated haploidentical PBSC grafts.

NGR-TNF, a novel vascular-targeting agent, does not induce cytokine recruitment of proangiogenic bone marrow-derived cells

Background:

Administration of certain chemotherapy drugs at the maximum tolerated dose, vascular-disrupting agents (VDAs) and irradiation can induce mobilisation and tumour homing of proangiogenic bone marrow-derived cells (BMDCs). Increases in cytokines and chemokines contribute to such mobilisation that eventually promotes tumour (re)growth. NGR-TNF is a vascular-targeting agent in advanced clinical development, coupling the CNGRCG angiogenic vessel-homing peptide with tumour necrosis factor-alpha (TNF). We investigated whether NGR-TNF mobilises host BMDCs and growth factors.

Methods:

Blood was obtained from Lewis lung carcinoma and 4T1 tumour-bearing mice at different time points following NGR-TNF, VDA or anti-VEGFR2/flk-1 antibody treatment. Levels of circulating growth factors were assessed by ELISAs. BMDCs were characterised by FACS. Circulating endothelial progenitor cells were defined as CD45⁻/CD13⁺/flk-1⁺/CD117⁺/7AAD⁻, Tie2-expressing monocytes as CD45⁺/CD11b⁺/Tie2⁺ and myeloid-derived suppressor cells as CD45⁺/CD11b⁺/Gr1⁺ cells.

Results:

NGR-TNF decreases tumour blood vessel density-inducing apoptosis of tumour and tumour endothelial cells. Unlike VDAs, or high-dose NGR-TNF, lower doses of NGR-TNF, comparable to those used in clinical trials, neither mobilise nor recruit to the tumour site proangiogenic BMDCs or induce host growth factors.

Conclusion:

Low-dose NGR-TNF exerts antitumour activity without inducing proangiogenic host responses, conceivably important for preventing/overcoming resistance and designing combination therapeutic strategies.

Two doses of NGR-hTNF in combination with capecitabine plus oxaliplatin in colorectal cancer patients failing standard therapies

Background: asparagine-glycine-arginine-human tumour necrosis factor (NGR-hTNF), an agent selectively damaging the tumour vasculature, showed a biphasic dose–response curve in preclinical models. Previous phase I trials of NGR-hTNF indicated 0.8 and 45 μg/m² as optimal biological and maximum-tolerated dose, respectively.

Patients and methods: Two sequential cohorts of 12 colorectal cancer (CRC) patients who had failed standard therapies received NGR-hTNF 0.8 or 45 μg/m² in combination with capecitabine–oxaliplatin (XELOX).

Results: Median number of prior treatment lines was 3 in the low-dose and 2 in the high-dose cohort. Overall, 21 patients had been pretreated with oxaliplatin-based regimens. No grade 3–4 NGR-hTNF-related toxicities were observed. Grade 1–2 chills were reported in 43% and 40% of cycles in the low-dose and high-dose cohorts, respectively. In the low-dose cohort, one patient achieved a partial response and five had stable disease for a median of 4.6 months. In the high-dose cohort, six patients had stable disease for a median of 3.6 months. Three-month progression-free survival (PFS) rates were 50% and 33% in the low-dose and high-dose cohort, respectively. Three patients in low-dose cohort experienced PFS longer than PFS on last prior therapy.

Conclusions: Both NGR-hTNF doses were safely combined with XELOX in pretreated CRC patients. Hint of activity was apparent only with low-dose NGR-hTNF.

Progress and prospects: graft-versus-host disease

Graft-versus-host disease (GvHD) is one of the major complications of allogeneic hematopoietic stem cell transplantation, an otherwise highly effective therapeutic modality for patients affected by hematological diseases. The main inducers of GvHD are alloreactive donor T cells, which recognize host antigens presented by recipient cells. The critical role of lymphocytes in GvHD is well documented by the observation that T-cell depletion from the graft prevents GvHD. Unfortunately, the removal of donor lymphocytes from the graft increases the incidence of disease relapse and life-threatening infectious complications. Gene transfer technologies are promising tools to manipulate donor T-cell immunity to enforce graft-versus-tumor/graft-versus-infection while preventing or controlling GvHD. For this purpose, several cell and gene transfer approaches have been investigated at the preclinical level and implemented in clinical trials.

Phase II study of NGR-hTNF, a selective vascular targeting agent (VTA), in previously treated patients with hepatocellular carcinoma (HCC)

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Background: NGR-hTNF is a VTA exploiting a tumor-homing peptide (NGR) that selectively binds to aminopeptidase N (CD13) overexpressed on tumor blood vessels. In preclinical models, NGR-hTNF has shown potent anti-vascular and antitumor activity, both at low and at high doses. Methods: Patients with recurrent or metastatic HCC were treated with NGR-hTNF given intravenously at 0.8 μg/m2 as 1-hour infusion every 3 weeks (q3w). This phase II trial had a 2-stage design with 16 and a total of 27 patients to be enrolled after first and second stage, respectively. Progression-free survival (PFS) was the primary endpoint with reassessment performed q6w according to WHO criteria. Results: 27 patients with progressive disease following prior loco- regional treatment (59%), systemic therapy (56%), or both (33%) were evaluated over 86 cycles (range, 1 to 14). Patient characteristics were: median age 67 years (range, 53 to 79); M/F 21/6; PS 0/1 18/9; Child-Pugh class A/B: 21/6. No grade 3–4 treatment-related adverse events were observed. Main grade 1–2 toxicities were short-lasting infusion-related constitutional symptoms, including chills (55%). Median PFS was 2.3 months (95% CI, 1.7–2.9 months). One complete response (4%) lasting 9.0+ months was observed in a sorafenib-refractory patient and one partial response (4%) was reported in a Child-Pugh class B patient. Additionally, a 28% tumor shrinkage was detected in one out of six patients (22%) experiencing stable disease. The median PFS duration in stable or responder patients was 4.3 months (95% CI, 2.7–5.8 months). With a median follow-up of 7.6 months, the overall survival rates at 3 and 6 months were 82% and 60%, respectively. Conclusions: NGR-hTNF given at 0.8 μg/m2 every 3 weeks is well tolerated and appears to have promising antitumor activity in previously treated patients with advanced HCC. The drug will be further developed in this setting and, currently, an additional cohort of 12 patients has been enrolled and treated at same dose with a weekly schedule.

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Phase II study of NGR-hTNF, a selective vascular targeting agent (VTA), in previously treated patients with malignant pleural mesothelioma (MPM)

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Background: NGR-hTNF is a VTA exploiting a tumor-homing peptide (NGR) that selectively binds to an aminopeptidase N (CD13) overexpressed on tumor blood vessels. In preclinical models, NGR-hTNF has shown potent anti-vascular and antitumor activity, both at low and at high doses. Methods: Patients with advanced MPM were treated with a low-dose of NGR-hTNF given intravenously at 0.8 μg/m2 as 1-hour infusion every 3 weeks (q3w). This phase II trial had a 2-stage design with 16 and a total of 27 patients to be enrolled after first and second stage, respectively. Primary endpoint was progression-free survival (PFS) with restaging performed q6w according to MPM-modified RECIST criteria. Results: From May 2007 to January 2008, forty-three patients with radiologically-documented progressive disease after a pemetrexed-based regimen were evaluated over 167 cycles (range, 1 to 17). Patient characteristics were: median age 64 years (range, 54 to 80); male/female 27/16; epithelial/non-epithelial histology 34/9; PS 0/1/2 24/10/9; EORTC score good/poor 34/9. Main grade 1–2 toxicity was chills (71%), transiently occurring after the first infusions. Only one grade 3 treatment-related toxicity was observed. One patient (2%) had a partial response lasting 7.1+ months and 17 patients (40%) maintained stable disease for a median duration of 4.4 months (range, 1.3 to 12.4+ months). The median and 3-month PFS were 2.8 months and 43%, respectively, whereas the median and 1-year overall survival were 11.6 months and 48%, respectively. In an additional 14 patients treated at same dose with a weekly schedule, there was any suggestion of toxicity exacerbation. In this cohort, the PFS rate at 6 months was 36%, with 7 patients (50%) experiencing stable disease for a median duration of 6.9 months (range, 2.4 to 9.3+ months). Conclusions: NGR-hTNF 0.8 μg/m2 weekly is well tolerated, showing prolonged disease control in previously treated MPM patients, and will be further developed in this setting.

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Phase Ib study of NGR-hTNF, a selective vascular targeting agent (VTA), in combination with cisplatin in patients with refractory solid tumors

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Background: NGR-hTNF is a VTA exploiting a tumor-homing-peptide (NGR) that selectively binds to an aminopeptidase N/CD13 overexpressed on tumor blood vessels. In preclinical models, significant synergy between low-dose NGR-hTNF and cisplatin was shown. Methods: Patients with resistant/refractory solid tumors were treated with NGR-hTNF given with a low-dose, doubling-dose scheme (0.2–0.4–0.8–1.6 μg/m2) as 1-hour intravenous infusion, in combination with cisplatin 80 mg/m2, both given every 3 weeks. A 3+3 escalation/de-escalation design was followed. PK sampling was performed after the first 3 cycles. DLT definition: any G3–4 toxicity related to NGR-hTNF. Results: 22 patients (median age: 60 years, range, 47–75; 14M/8F; ECOG PS 0/1 12/10) with different tumor types were evaluated over 77 cycles (range, 1–10). Median number of prior regimens was 3 (range, 1–6) and 12 patients (55%) were previously treated with platinum-based regimens. Both NGR-hTNF Cmax and AUC increased proportionally with dose. The combination was safe without PK interaction or exacerbation of platinum-associated toxicity profile. No shedding of soluble TNF receptors was observed up to 0.8 μg/m2. As expected for the low-dose range explored, MTD was not reached and no DLTs were registered at 0.2 μg/m2 (n = 4), 0.4 μg/m2 (n = 3) and 1.6 μg/m2 (n = 3). At 0.8 μg/m2, a patient had a G3 transient acute infusion reaction. This cohort was expanded up to 6 patients for safety reasons, with no DLTs registered, and up to 12 patients, for preliminary activity evaluation. At this dose level of 0.8 μg/m2, two lung cancer patients, both pre-treated with platinum, achieved a partial response (-79%) and a significant tumor shrinkage (-28%) lasting 7.2 and 6.7 months, respectively, and an additional 4 patients experienced stable disease for a median duration of 6.4 months. The median progression-free survival for all patients (n = 22), for patients enrolled at 0.8 μg/m2 (n = 12), and for patients pre-treated with platinum (n = 9) was 2.7, 4.7, and 4.3 months, respectively. Conclusions: The combination of NGR-hTNF 0.8 μg/m2 with cisplatin 80 mg/m2 shows a favourable toxicity profile and promising antitumor activity.

[Table: see text]

Phase II study of NGR-hTNF, a selective vascular targeting agent (VTA), administered as single agent in patients (pts) with colorectal cancer (CRC) refractory to standard regimens

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Background: NGR-hTNF is a VTA exploiting a tumor-homing peptide (NGR) that selectively binds to an aminopeptidase N/CD13 overexpressed by tumor blood vessels. In preclinical models, NGR-hTNF showed antitumor activity both at low and at high doses. Methods: Pts with CRC resistant/refractory to standard treatments, including biological agents, were treated with low-dose NGR-hTNF given intravenously at 0.8 μg/m2 as 1-hour infusion every 3 weeks (q3w). This phase II trial had a 2-stage design with 16 and 27 pts to be enrolled after first and second stage, respectively. Progression-free survival (PFS) was the primary end-point with reassessment performed q6w. Results: From January to May 2007, 33 pts with radiologically- documented progressive disease after last therapy were evaluated over 111 cycles (range, 1–10). Pts characteristics were: median age: 65 years (range, 53 to 79); M/F 16/17; PS 0/1 26/7. Median number of prior regimens was 3 (range, 2 to 5). Eight pts (25%) were pre-treated with ≥4 lines and 22 (67%) with biological agents. Neither grade 3–4 treatment-related adverse events nor toxicity-related deaths were observed. Main grade 1–2 toxicities per patient were infusion-related chills (47%) and transient blood pressure increase (9%). One partial response (3%) lasting 5 months and 12 stable diseases (36%) were reported. Median PFS was 2.5 months (95% CI, 2.2–2.8). In a post-hoc analysis, no differences in PFS were detected according to baseline characteristics. With a median follow-up time of 18.4 months (95% CI, 18.3–18.5), 11 pts (33%) were still alive. Median overall survival (OS) was 13.1 months and the 2-year OS rate was 22%. In the subset of stable or responder pts, the median PFS and OS were 3.8 months and 15.4 months, respectively. The 6-month PFS rate in the prior-biological and biological-naïve cohorts was 5% and 20%, respectively, whereas 1-year OS rate was 41% and 72%, respectively. Conclusions: Based on the favorable toxicity profile and disease control in heavily pre-treated CRC patients, NGR-hTNF will be further developed in combination with standard chemotherapy.

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Potential of gene therapy in bone marrow transplantation

Gene therapy, initiated as a treatment for inherited disorders such as adenosine deaminase deficiency, is now a promising therapeutic strategy for malignancies and other acquired diseases. In particular, in the field of bone marrow transplantation (BMT) for haematological malignancies, the gene transfer of the suicide gene HSV-TK into donor lymphocytes allows control of the severe complication graft-versus-host disease (GvHD). The transfer of the HSV-TK suicide gene confers selective sensitivity to the drug ganciclovir, allowing in vivo elimination of the donor T-cells if severe GvHD occurs. In Italy, the first pilot study on delayed infusion of genetically engineered donor lymphocytes after T-depleted allogeneic BMT documented efficacy of engineered donor lymphocytes in terms of anti-tumour activity and efficiency of the suicide system. GvHD developed in 3 out of 8 patients and was successfully treated by ganciclovir administration.

Gene therapy: efforts at developing large animal models for autologous bone marrow transplant and gene transfer with retroviral vectors

Two new large animal models, non-human primates and fetal sheep, have been developed in an effort to determine the feasibility of using retroviruses for gene therapy. The retroviral vectors N2 and SAX have been used to introduce the genes for neomycin phosphotransferase (neoR, conferring resistance to the antibiotic G418) and human adenosine deaminase (ADA; EC 3.5.4.17), respectively. Varying levels of human ADA activity have been detected in six of the eight SAX-treated monkeys analysed. In the monkey with the greatest activity, human ADA levels approximately 0.5% of endogenous monkey ADA levels were detected. By in situ hybridization, roughly one in 100 bone marrow cells were found to express vector DNA. Sheep have been used for studies of the infectability of fetal blood progenitors in vivo. Blood cells were treated with the N2 vector at the 96th day of gestation, and marrow cells were assayed for the presence of G418-resistant haematopoietic progenitors, starting from one week after birth (62 days after treatment). Up to 33% of colony-forming progenitors were drug resistant initially and, although the proportion of resistant colony-forming units declined, a level of 10% has been found 153 days after transplantation. Human bone marrow has also been treated with the N2 vector, resulting in 1-2% G418-resistant progenitors.

Optimal safety profile and anticancer activity of NGRhTNF coupled with doxorubicin (NGR003 modified phase I combo trial)

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Background: NGRhTNF is a vascular targeting agent (VTA) exploiting a tumour homing peptide (CNGRCG) selectively binding angiogenic vessels in solid tumors, where NGRhTNF specific binding relies on dynamic interactions with TNF-receptors and aminopeptidase N (CD13). NGRhTNF combines activity on tumour vascular permeability and direct anticancer activity. At low dose, NGRhTNF increases tumour vascular permeability. Consistently, mouse preclinical data indicate significant synergy between low dose NGRhTNF and cytotoxic agents. Thus, we tested NGRhTNF in combination with doxorubicin. Methods: 4 doses of NGRhTNF (0.2, 0.4, 0.8 and 1.6 μg/m2) in combination with doxorubicin (75 mg/m2) have been administered every 3 weeks in 15 patients.Main end- points included safety, anticancer activity and pharmacokinetic. Measurement of circulating tumour (CTC) and endothelial cells, sTNF receptors, along with plasma chemokine profile are being performed. Results: All patients were enrolled (5F/10M). Toxicity was limited to constitutional symptoms, most frequently chills. After a median follow-up of 12 weeks (range 3–28), 5 episodes of chills (1 grade I and 4 grade II) were reported in 4/15 patients.One episode of grade I hypertension was reported. Of note, the toxicity profile commonly-associated to doxorubicin has not been exacerbated. Stabilization of disease occurred in 10/15 patients lasting 13 weeks (range 6–28 with 5 patients still ongoing at December 2006). In addition, partial response was achieved in 2 patients, lasting 23 and 14 (still ongoing) weeks, respectively. It is worth noting that anticancer activity was observed in 12/15 patients of whom 9 had previously received anthracycline-containing regimens and 5 were anthracycline-resistant suggesting a role of NGRhTNF in inducing tumour sensitivity to doxorubicin. Finally, changes in CTC levels over time consistently matched the clinical outcome. Conclusions: Coupling NGRhTNF with doxorubicin induced anticancer activity along with an optimal safety profile in pretreated patients providing support for the phase II combination studies addressing diseases suitable for anthracycline treatment such as sarcoma and ovarian cancer, and planned to start in early 2007.

No significant financial relationships to disclose.

A phase I study of NGR-TNF, a novel vascular targeting agent, in patients with refractory solid tumors (EORTC 16041)

14074

Background: NGR-TNF is a novel agent exploiting a tumour homing peptide (cNGRCG) that selectively targets CD13 that is expressed on the neovasculature of solid tumors. Preclinical data show that its antitumour activity is achieved by a change of vascular permeability (at low doses) and damage of tumour-associated blood vessels (at high doses). This phase I study is being conducted to assess its safety, PK, PD, MTD, and optimal biological dose in patients (pts) with advanced solid tumours. Methods: NGR-TNF was administered once every 3 weeks by a 20 min IV infusion to cohorts of 3–6 pts. The starting dose was 0.2 μg/m2. Dose escalation was performed with a doubling of the dose until grade 2 toxicity was observed; thereafter a modified Fibonacci schedule was used. PK and PD analysis in blood was performed during the first 4 cycles. DCE-MRI was performed in cycle 1 at baseline and 2 hours after start of the infusion to document modification of the tumour vascularity. Anti-tumour activity was assessed by CT scan every 2 cycles. Results: 45 pts were treated and 133 cycles of treatment completed up to now. 12 DLs have been visited (0.2 to 14.36 μg/m2). One DLT (bronchospasm G 3) was observed at DL4 (1.3 μg/m2) and the DL was extended to 7 pts. As no other DLT was observed, dose escalation was continued. Since then no additional pt experienced dose-limiting toxicity. As 3/18 first pts experienced chills G 2 during injection time, the study was amended and infusion time increased to 1 hour. Since then 1/14 next pts had G 2 chills. Overall most frequently related adverse events reported in the first 34 pts: chills 76%, fever 44%, nausea 20%, constipation 12%, diarrhea 9%, anorexia and hypotension 6%. PK/PD analysis for the plasma levels of TNF-RI and TNF-RII showed a better profile for the 60 min compared with the 20 min infusion. At DL = 1.3 μg/m2 most pts showed a decrease in kep and the number of pixels with a low fraction of kep and Ktrans significantly increased (p<0.05), as seen with other anti- vascular agents. Stable disease was observed in 39% of pts, with a median duration of 11 wks (range 5–36). No responses were observed. Conclusions: NGR-hTNF is well tolerated and some biological activity was observed by DCE-MRI. Study enrollment is ongoing.

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