side rodent cells(73,74).

Aware of this work, the Oxford and Cambridge researchers instilled plasmid-contain-ing liposomes into lightly anaesthetised CF mice. The CFTR-gene-containing plasmid corrected chloride transport in the trachea, returning it to a level seen in normal mice.In their paper, published in `Nature` in March 1993, the researchers wrote, "Our results illustrate the invaluable role of transgenic null cf/cf mice in assessing the efficency of various gene therapy approaches. We have shown that functional statement of CFTR not only corrects the primary ion transport defect of the trachea... but also corrects secondary alterations in sodium absorption which are a consequence of loss                          of CFTR function. There seems to be no reason why this approach should not betransferable to humans for treatment of the pulmonary features of CF"(75).

Two days after `Nature` published their paper, `New Scientist` carried an article on the research -quoting one of the researchers as saying, "There is no guarantee that the success with mice can be reproduced in human cystic fibrosis patients, and clinical trials will take time"(76).

Almost three months prior to the announcement by the Oxford and Cambridge researchers, Prof Bob Williamson and colleagues at St Mary`s Hospital and the RoyalBrompton Hospital, in London, had proposed use of a liposome-gene construct in gene therapy, and used an approach similar to that of the Oxford and Cambridge researchers(77).

In conjunction with the Royal Brompton Hospital clinical team, gene therapy was tried in Edinburgh mice. The CFTR gene was administered to mice in liposomes in fine droplets to the lungs and by direct installation to the gut. Although the treated mice did express human CFTR genes, the level varied in the trachea, peripheral lung, and rectum tissue studied -and differences were seen in the tissues of each mouse and between mice(78).

As to the crucial issue of the lungs, the researchers reported that chloride transport was corrected in some, but only partially corrected in other mice. They also admitted to only achieving "modest" correction in the intestinal tract(78).

The Royal Brompton Hospital team published their findings in October 1993, stating "The airways of these [Edinburgh] cf/cf mice show many similarities to the pathology found in [human] CF subjects, but in the animals used in this study, bronchi were not filledwith purulent secretions. Effective delivery is, therefore, more likely than in the diseased human CF airway which will probably be the first targetted in trials of gene therapy. Despite such an apparent advantage, complete correction was only achieved in some animals"(78).

According to the Cystic Fibrosis Trust, work carried out with both the Cambridge CF mice (i.e. as used by Oxford and Cambridge researchers) and Edinburgh CF mice (i.e. as used by the Royal Brompton team) was the basis for two British clinical trials(79).

Human Clinical Trials
Whilst clinical trials were awaiting approval in the UK(80), American researchers began using attenuated adenovirus as the vector, rather than liposome(81) -as adenovirus occur naturally in the human airways, and foreign genes can be easily inserted to produce large quantities of recombinant virus(82).

US clinical trials with adenovirus-vectored CFTR genes were conducted at the National Heart, Lung and Blood Institute (NHLB), and were reported on, in `New Scientist`, in September 1993. The trial had to be stopped after a human CF patient developed lung inflammation. Researchers warned that although the adenovirus vector might prove highly effective at first introduction of the CFTR gene, the level of gene statement n the lungs sometimes fell sharply on subsequent applications. Within months, the clinical trials were running into unexpected problems(83).

Meanwhile, at the Howard Hughes Medical Institute in Iowa, Dr Michael Welsh and colleagues reported on adenovirus-mediated transfer of the gene to nasal cells(84).

A year later (in September 1994), Dr Arnold Crystal of the Cornell Medical Center, New York, used adenovirus vectors to deliver the gene to four patients(85).  Although others had used adenoviruses, this was the first trial of delivery of CFTR gene to the bronchial epithelium(86,87). Symptoms (thought to be an inflammation reaction witin the lung) developed in patients given the highest dose of the vector. This clinical trial (funded by the NHLB, the Cystic Fibrosis Foundation, and the Will Rogers Memorial Fund) continued, and as of September 1994, eight patients had received the treatment(88).

The NHLB also supported studies by a further four research teams - three of whom used adenovirus vectors, whilst the other used liposomes(89).

Two British doctors, of the national Heart and Lung Institute in London, suggested that further studies were necessary to establish how useful delivery of adenovirus vectors to the bronchial epithelium might be(89).

By November 1996, reports of the US clinical trials, were being published, to treat CF with adenovirus vectors. These reports included that of Jim Wilson and colleagues of the University of Pennsylvania Medical School, who had found the airways of patients had become inflamed after breathing in aerosis of adenoviruses(90).

Disappointing results from the clinical trials led the US National Institute of Health to re-consider its whole approach to gene therapy, and set up a committee to report on its examination(90). In the Spring of 1995, Harold Varmus, Director of the NIH, stated in a summary of his remarks to the panel of the NIH committee, "Despite enthusiastic interest and early signs of safety and biological feasibility, however, evidence for therapeutic benefit to patients is meager"(91).

Failure of the methodology was expressed by Robert Erickson (of the University of Arizona, and a member of the Office of Recombinant DNA Activities at the US NIH), "A lot of things are being tried without adequate basic science. We need to have ways of delivering genes safely that lead to long-term statement"(92).

Ron Crystal, of the Cornell Medical Center (who, in September 1994 had reported on his clinical trial with adenovirus) stressed that as humans are very different to animals, researchers cannot rely on the results from animal experimentation(93). He is also quoted as saying, "I think human experimentation is absolutely critical in this field"(94).

The US NIH `Report and Recommendations of the Panel to Assess the NIH Investment in Research on Gene Therapy` appeared in December 1995, with the authors concluding that gene therapists were promoting the idea that "gene therapy is further developed and more succesful than it actually is", and the review panel commentedthat, contrary to the general impression, "Clinical efficacy has not been definitively demonstrated at this time in any gene therapy protocol, despite anecdotal claims of successful therapy"(95).

Harold Varmus (who had selected the 14 members of the panel of experts) stated, "the announcement of a gene being discovered is tantamount to the belief that gene
therapy exists for the condition. We`ve seen an extrapolation from hope to hype... In the long run, this will be destructive to basic clinical science"(96).

Stuart H Orion (of Harvard Medical School), who co-chaired the panel said, "There is no established efficacy of any gene therapy protocol"(97).

In a review of the NIH Report for `Science`, Eliot Marshall wrote, "the [NIH] panellists affirmed the value of clinical research, noting that animals often aren`t valid substitutes for humans, and that human studies can open new avenues of research"(98).

The world`s first clinical trials of CF gene therapy using liposomes were started in Britain at the National Heart and Lung Institute, Royal Brompton Hospital - with funding from the Medical Research Council and the Cystic Fibrosis Trust - in the summer of 1993(99). The plan was to administer liposomes in a nasal spray to nine young male volunteers to test if the technique was safe and effective. If it was, then the spray would be given directly to the lungs of CF patients, but `New Scientist` in September 1993, referred to the fact that until the results of the first trials with liposomes were known, there was no guarantee that liposome would not run into the same problems experienced with adenovirus vectors(99).

On 16th September 1993, `SCRIP` reported that UK researchers had completed a preliminary clinical study in which the gene had been delivered to the nasal epithelium by liposome. Although it was speculated that the CFTR gene transfer might be feasible, Drs Alton and Geddes, of the National Heart and Lung Institute in London, thought that it was unclear whether liposomes would be effective enough to produce
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benefits for human CF sufferers. Of the US study (see above), they suggested that further studies were necessary to establish how useful delivery of adenovirus vectors to the bronchial epithelium might be(100).

`SCRIP` considered, "It is therefore useful to have both systems evaluated in parallel" but added, "it would be a mistake to enter into large-scale clinical trials until these questions have been resolved"(100).

In 1994, it was noted that because of the very slow rate of progress of cystic fibrosis lung disease, the value of any new treatment was considered to be very difficult to prove without a very long study period(101).