EP Vantage Interview - LSO seeing the light on data and a deal

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Light Sciences Oncology is approaching the release of data from two pivotal studies underway with its lead product, Aptocine, a novel light-activated approach to killing tumours that is attracting a lot of interest from potential partners, according to Llew Keltner, the company’s chief executive.

Because patients have lived a lot longer than expected in the first phase III study, in hepatocellular carcinoma, it could well read out at the same time as a more recently initiated trial, in metastatic colorectal cancer, possibly this summer. Generating solid late-stage data will be an important milestone for the private company and its technology, however, with “serious discussions” ongoing with a top five pharma company about a deal, which Dr Keltner tells EP Vantage could go ahead before the data is published, validation could arrive even sooner.

“The bottom line is we have had intense discussions with all the major oncology players, and all are in the position of saying `let’s see the data'. But the main company has a strategic imperative that pushes them ahead,” to get the deal done sooner, he says.  

The potential partner has a “compelling need regionally” for a liver cancer therapy, which is driving their interest. The debate is over whether to strike a global deal.

"But we are both going to explore the possibilities for another 30 days or so, and we will then have a better idea where we stand. Deals of this sort typically take some time to complete, but in a perfect world, a deal before the end of the first quarter would be possible since we have document templates ready and waiting for terms," he says.

Shaking off stigma

If a deal does not materialise in the next few months, Light Sciences has enough cash to last into 2011, by which time Aptocine should be filed with the FDA in both lead indications. If the data is positive and still no deal materialises, Dr Keltner will consider taking the company public if a stronger appetite for biotech IPOs has emerged, to commence the process of launching the drug.

Although he clearly expects a deal to be done Dr Keltner is cognisant of shifting trends in deal making, pointing out that partners now need a lot more proof that the product will sell before signing on the dotted line.

This could well apply to Aptocine; the novel therapy which utilises a drug activator would appear to represent a harder sell than a simple pill. The company also has to shake off the stigma of photodynamic therapies, which have never become a commercial success in oncology, largely due to their expense, complexity and side effects.

Systemic effect

Aptocine is very different from older light activated therapies, sometimes known as photodynamic therapies, which can require large, expensive lasers, surgery to access to the tumour and prolonged periods of photosensitivity for patients.

Generically known as talaporfin sodium, the drug used is a water soluble, biologically inert compound that only becomes active in the presence of light, and is removed very quickly from the body. Once a patient is injected with the compound the activator, a tiny array of LEDs located at the end of a very narrow micro-wire, is inserted into the body and then the tumour, in a simple process similar to a biopsy. Low intensity light from the LED activates each molecule of Aptocine many times, resulting in a continuous supply of singlet oxygen, a damaging molecule which causes tumour cells to die by apoptosis.

Interestingly, the company believes that not only does Aptocine kill tumours locally, but that it also has a systemic effect. They have hypothesised that this occurs because the apoptotic mass expresses a large amount of tumour specific antigen which triggers a T-cell response, prompting the immune system to attack other untreated tumours elsewhere in the body.

Light Sciences presented data on these systemic findings at Asco last year, and further pre-clinical work is ongoing to establish exactly what is going on. News of a systemic effect triggered a great deal of interest in Aptocine from partners, Dr Keltner says; a therapy that only acts locally would be perceived as a lot less valuable.

The company is hoping that the two ongoing phase III trials will generate evidence that Aptocine increases overall survival in the treated population, and further evidence of a systemic effect.

Foot race

The liver cancer trial, which started enrolling in November 2006, will be of particular interest. Nexavar is currently the only drug approved to treat this cancer and does not bring a huge survival advantage, whilst the side effect profile can be severe.

Nexavar was approved on the basis of median survival of 10.7 months, versus 7.9 months for patients given a placebo, in a trial called Sharp.

“Although the populations in two different trials are rarely comparable, the overall survival behaviour of patients in the Aptocine trial makes it clear that there is a very strong likelihood that survival in both arms will be considerably longer than in either arm of the Nexavar Sharp trial," Dr Keltner says.

The final death in the liver cancer trial is expected around May, whilst the 400th progression in the colon cancer study, which will trigger the final analysis, could happen in June.

“At the moment it’s a foot race to see which data set reads out first,” he says.

With deal talks ongoing at the same time, Light Sciences Oncology is facing a busy year.

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