CF Gene Therapy Clinical Trials
Introduction
CF gene therapy approaches have been based on the assumption that the target cell population is the respiratory epithelial cells lining the lung, although the majority of clinical trials have used delivery of the GTA to the nasal and maxillary sinus epithelia of CF patient volunteers as a surrogate tissue. In total, there have been 25 published clinical trials for CF and non-viral approaches have accounted for nine of these (Griesenbach & Alton 2009).
The first non-viral clinical trials assessed the safety and efficacy of a single nasal delivery of plasmid DNA containing the CFTR cDNA under the transcriptional control of the SV40 (Caplen et al. 1995) or RSV 3'LTR promoters (Gill et al. 1997) complexed with DC-Chol:DOPE liposomes. Evidence for plasmid DNA transfer, vector-derived CFTR mRNA expression and partial correction of the CFTR Cl- channel defect was obtained in a subset of subjects. Alternative formulations, in which plasmid DNA contained the human CMV immediate early enhancer/promoter, were complexed with DOTAP liposomes (Porteous et al. 1997), EDMPC:Chol liposomes (Noone et al. 2000), or a peptide consisting of the sequence CK30 (Konstan et al. 2004) and were broadly shown to be similarly effective.
Crucially, no important safety considerations were raised after nasal application of any of these formulations. The target cells of the respiratory epithelium are mostly slowly dividing or terminally differentiated, thus ultimately repeated administration of the GTA will be required to treat the chronic lung disease.
The repeated administration of viral vectors appears to be limited by the existence of pre existing neutralising antibodies (Rosenecker et al. 1996), or antibodies produced in response to vector delivery (Halbert et al. 1997). Successful repeat administration of non viral vectors without loss of efficacy has been demonstrated in the human airways after delivery of three doses of plasmid DNA complexed with DC-Chol:DOPE liposomes (Hyde et al. 2000).
Collectively, these clinical studies provided 'proof-of-principle' for CF non viral gene therapy, but highlighted the need for development of formulations with enhanced efficacy.
Figure from Hyde et al 2000. (a) CFTR staining (red) from a non-CF individual, (b) a CF individual before treatment and (c & d) post-treatment.
Adenovirus Clinical Trials: 1993-2001 (10)
| Author/Year | Organ | Design | Placebo | Repeat | N | Results |
|---|---|---|---|---|---|---|
| Zabner, 1993 | Nose | Dose-escalation 2e6 – 5e7 pfu n = 1/dose |
No | No | 3 | NPD: decreased baseline towards non-CF values mRNA: −ve, protein: −ve |
| Crystal, 1994 | Lung | Dose-escalation 2e6 - 5e9 pfu n = 1–2/dose |
No | No | 4 | mRNA: − ve protein: 1/4 + ve Safety: no vector shedding At highest dose transient inflammation. |
| Crystal, 1994 | Nose | Dose-escalation 2e5 – 5e7 pfu n = 2/dose |
No | No | 4 | NPD: inconclusive, too variable mRNA: 1/4 + ve, protein: 1/4 + |
| Hay, 1995 | Nose | Dose-escalation 2e5 – 5e8.5 pfu n = 1–2/dose |
No | No | 9 | NPD: decreased baseline + amiloride towards non-CF values Partial correction of Cl− transport |
| Knowles, 1995 | Nose | Dose-escalation 2e7 – 5e10 pfu n = 3/dose Vehicle control applied on contralat nostril |
No | No | 12 | NPD: no change mRNA: 5/12 + ve Safety: no toxic effects at low doses At highest dose mild mucosal inflammation 2/3 patients |
| Zabner, 1996 | Nose | Dose-escalation repeat administration 2 doses 2e7 –1e10 pfu n = 4–6/dose |
No | Yes | 6 | NPD: partial correction of Cl− in some patients, but reduced effect with subsequent administration. All patients developed serum antibodies to vector, but not CFTR |
| Bellon, 1997 | Nose | Dose-escalation 1e5 – 4e8 pfu n = 2/dose Dose-escalation 1e7 –5.4e8 pfu n = 2/d |
No | No | 6 | DNA: 6/6 + ve mRNA: 4/6 + ve, protein: 4/6 + ve Expression was transient in nose |
| Bellon, 1997 | Lung | Dose-escalation 1e7 – 5.4e8 pfu n = 2/dose |
No | No | 6 | DNA: 1/6 + ve mRNA: 1/6 + ve, protein: 2/6 + ve Expression was transient lung |
| Harvey, 1999 | Lung | Dose escalation Repeat administration 3 doses 1e6 – 1e9 pfu n = 2/dose |
No | Yes | 14 | Sampled 3 and 30 days after each administration mRNA: 1st administration + ve only with highest dose, transient (− ve by day 30) 2nd administration + ve only with intermediate dose, − ve by day 30 3rd administration no expression Anti-Ad neutralising antibodies detected but no close correlation with loss of expression |
| Zuckerman, 1999 | Lung | Dose-escalation 2e9 - 2e11 pfu n = 2–3/dose |
No | No | 11 | DNA: + ve on day 4, transient Immune response: Ad-specific T-cells, mild humoral response Safety: mild flu-like symptoms observed, resolved about day 10 |
| Joseph, 2001 | Lung | Dose-escalation 8e6 – 2.5e10 pfu n = 2–3/dose |
No | No | 36 | DNA: 4/5 + ve on day 2 mRNA: 3/5 + ve on day 2 |
| Perricone, 2001 | Lung | Dose escalation 8e6 - 2.5e10 IU/patient Lobar instillation or aerosol |
No | No | 14 | DNA: all + ve on day 2 mRNA: 4/13 + ve on day 2 Expression transient, undetected by day 7. < 3% of airway epithelial cells transfected. Safety: Mild, non-specific inflammatory response (fevers, myalgia). Cleared within 24 h |
AAV2 Clinical Trials: 1999-2007 (6)
| Author/Year | Organ | Design | Placebo | Repeat | N | Results |
|---|---|---|---|---|---|---|
| Wagner, 1999 | Sinus | Dose-escalation 1 × 102–1 × 105 RU Single and two doses n = 5/group |
No | No | 10 | DNA: 7/10 + ve day 14 DNA: 1/10 + ve day 41 DNA: 1/10 + ve day 70 CFTR mRNA: − ve NPD: partial Cl− correction in some cases, effect transient |
| Aitken, 2001 | Lung | Dose escalation 1e10 – 1e13 DRP n = 3/group |
No | No | 12 | DNA: 6/6 + ve up to day 30 with two highest doses mRNA: − ve Safety: several adverse effects, three of which possible related to study (pneumonia, exacerbation) |
| Wagner, 2002 | Nose | 1 nostril 1e5 RU contralateral nostril placebo (n = 23) |
No | No | 25 | No change in: rate of sinusitis relapse, NPD, histopathology and IL-8 IL-10: increased vs. placebo at day 90 |
| Flotte, 2003 | Nose | Dose-escalation 3e1 RU – 1e9 RU placebo (n = 25) contralateral nostril |
No | No | 25 | Nose: NPD: no change Vector DNA: 2/25 + ve |
| Moss, 2004 | Lung | Repeat admin: 3 doses, 30 days apart 1e13 DRP (n = 37) |
Yes | Yes | 37 | DNA: 6/6 + ve (only assessed after 3rd dose) mRNA: − ve FEV1: trend in improvement day 30 IL-8 and IL-10: sputum IL-8 reduced after 1st dose, IL-10 no change Safety and immune response: well tolerated, active group developed AAV2-neutralising antibodies |
| Moss, 2007 | Lung | Repeat admin: 3 doses 30 days apart 1e13 DRP |
Yes | Yes | 102 | No changes in spirometry, days of antibiotic use or induced sputum markers (IL-8 + neutrophil elastase) Safety: well tolerated |
Non-Viral Clinical Trials: 1997-2012 (9)
| Author/Year | Organ | Design | Placebo | Repeat | N | Results |
|---|---|---|---|---|---|---|
| Caplen, 1995 | Nose | DC-Chol/DOPE Dose escalation 10–300 µg DNA n = 3/dose |
Yes | No | 15 | Vector DNA: 7/8 + ve (some problems with false + ves) CFTR mRNA: − ve NPD: partial correction (20%) of Cl− defect towards normal at day 3, undetected by day 7 Safety: well tolerated |
| Gill, 1997 | Nose | DC-Chol/DOPE/pDNA 40 + 400 μg DNA/nostril n = 4/dose |
Yes | No | 15 | NPD: 2/8 transient correction of Cl− for 7–15 days SPQ: 5/8 showed CFTR function |
| Porteous, 1997 | Nose | DOTAP 400 µg DNA |
Yes | No | 16 | DNA: 7/8 + ve on days 3 and 7 DNA:2/7 + ve on day 28 mRNA: 2/8 + ve on days 3 and 7 NPD: 2/8 partial Cl− correction up to 4 weeks SPQ: − ve |
| Zabner, 1997 | Nose | GL67A v naked pDNA | No | No | 12 | DNA: 8/9 + ve RNA: − ve, technical problems NPD: statistically significant correction of Cl− with both GL67 and naked pDNA No difference between vectors |
| Alton, 1999 | Lung & Nose | GL67ApDNA Lung: 42.2 mg DNA Nose: 11.8 mg DNA Lipid only placebo |
Yes | No | 16 | Lung: DNA: 8/8 + ve RNA: − ve PD: statistically significant Cl− correction in active group, 25% of normal values SPQ: CFTR function in 5/6 patients Bacterial adherence: 5/6 patients in active group reduced bacterial binding compared to pre-treatment values Inflammation: significant reduction of inflammatory cells in sputum in active group similar results (DNA, mRNA, PD, SPQ, bacterial adherence ) in the nose Safety: 7/8 patients in active group developed flu-like symptoms (fever, headache), resolved within 36 h. 6/8 patients in both groups had mild airway symptoms |
| Hyde, 2000 | Nose | DC-Chol/DOPE/pDNA Repeat administration 3 doses 400 μg DNA/nostril |
Yes | Yes | 12 | DNA: 6/9 + ve after ≥ one dose DNA: 1/9 + ve for all 3 mRNA: 7/9 + ve after ≥ one dose mRNA: 1/9 + ve for all 3 Protein: 6/9 + ve after ≥ one dose; 2–15% epithelial cells transfected NPD: partial Cl− correction in individual patients SPQ: 5/9 showed CFTR function after ≥ one dose Bacterial adherence: no difference, but technical problems Immune responses: no response to CFTR Importantly, no loss of efficacy with repeated dosing |
| Noone, 2000 | Nose | EDMPC/pDNA Dose escalation 0.4–4 mg DNA placebo in contralateral nostril |
Yes | No | 12 | DNA: all + ve (some cross-contamination to placebo) mRNA: − ve NPD: no change |
| Ruiz, 2001 | Lung | GL67A/pDNA Dose-escalation 7.9–21.12 mg DNA |
No | No | 8 | mRNA: 4/8 + ve, 3/4 received highest dose Inflammatory response: 4/8 pronounced fever, myalgia within 6 h post-administration. Serum IL-6 increased, but no changes in IL-8, IL-1, TNF-α or IFN-γ. No antibodies to lipid or plasmid Lipid and DNA have synergistic effect on inflammation |
| Konstan, 2004 | Nose | DNA Nanoparticles Dose-escalation 0.8–8.0 mg DNA n = 2–6/dose contralateral nostril placebo |
Yes | No | 12 | DNA: 12/12 + ve in active but cross-contamination in placebo NPD: partial to complete Cl− correction 8/12, up to day 6 Safety: well tolerated, no adverse effects related to treatment |
What is Gene Therapy? (2008): CF gene therapy aims to insert a fully functional CFTR gene into the lung airway cells of people with the condition. Two main types of vector are used to deliver this new copy of the gene. A viral vector, engineered from viral particles or non-viral vectors, plasmid DNA molecules condensed by other chemical entities. More...
