Iressa Making a Comeback Bounce!!

[RandyW]

AZ's Iressa to make comeback

Tuesday , April 28, 2009

AstraZeneca's Iressa is set to make a comeback after a European committee recommended its use for a sub-group of lung cancer patients.

It marks a change in fortune for the drug, which was first launched in 2002 but suffered after poor data showed it failed to extend lives, and was then withdrawn in Europe.

The drug has since been eclipsed by Roche's rival treatment Tarceva, but could undergo a revival of fortunes after showing promise in a small number of patients.

Europe's CHMP committee has recommended Iressa for use in patients with locally advanced or metastatic non-small cell lung cancer with mutations in their epidermal growth factor receptor-tyrosine kinase (EGFR-TK).

These patients represent around 10-15% of patients newly diagnosed with lung cancer in France, Germany, Italy, Spain and UK each year.

The first EGFR receptor

When launched in 2002, Iressa was the first drug in the epidermal growth factor receptor (EGFR) class, which targets EGFR-TK, an enzyme which plays a key role in some non-small cell lung cancers.

Late stage trials in non-small cell lung cancer published in 2004 showed it failed to extend lives of patients when given alongside standard chemotherapy, dealing a blow to the drug 's prospects.

The company then tested the drug alone in pre-treated patients not eligible for further chemotherapy, but in 2005 AstraZeneca withdrew its European marketing application in this indication, when in a phase III study it failed to show significant improvement over a placebo.

AstraZeneca was able to keep the drug on the US market, though its use has been restricted and no new patients could access the therapy unless taking part in a clinical trial.

EGFR-TK is an enzyme that occurs naturally in the body, but mutations involving it can lead to its constant activation, which can result in uncontrolled cell division, which can then lead to cancer.

Iressa works by blocking activity of the mutations of the enzyme that help tumours to grow and spread.

Anders Ekblom, executive vice president for development at AstraZeneca, said the positive opinion on Iressa was an important step to addressing the unmet medical need of lung cancer patients in Europe, which "supports AstraZeneca's personalised healthcare strategy to develop the right medicine for the right patient".

He added: "If Iressa is approved, for the first time patients with these types of EGFR positive tumours will have a better alternative to chemotherapy as a first-line treatment."

Troubled past

Iressa is still licensed in 36 countries, largely in Asia, as treatment for patients with locally advanced or metastatic non-small cell lung cancer who have already received chemotherapy, but has so far failed to win approval in Europe.

But the potential approval in Europe is based on two new studies in special sub-groups of patients in whom Iressa exceeded its primary objectives.

In the first it demonstrated superior progression-free survival, greater tumour shrinkage, and significant quality of life benefits compared to carboplatin/paclitaxel doublet chemotherapy in clinically selected first-line patients in Asia.

In the second, it met its primary objective, demonstrating equivalent overall survival and significant quality of life benefits compared to standard chemotherapy in the pre-treated setting.

These were pre-planned sub-group analyses showed a significant improvement in PFS and ORR for IRESSA over docetaxel in patients with EGFR mutation positive tumours.

AstraZeneca is going to conduct a follow up study, to generate further data in a Caucasian patient population, and is in discussion with Europe's regulator about the endpoints.

Competition

But a comeback from Iressa could prove tough. One day after its new approval as a first-line treatment in lung cancer patients with genetic mutations in their epidermal growth factor receptor (EGFR), Roche announced it was working on a phase III trial to investigate the effectiveness of its drug Tarceva in the same patient group.

Tarceva, unlike Iressa, has been shown to benefit all patients, whether or not they have a mutant version of EGFR.

Iressa will build up sales on the back of the European approval, but is unlikely to be anything other than a niche product, with sales forecast to reach $474 million, or 2% of AstraZeneca group sales, in 2014.

[gpawelski]

Targeted treatments like Iressa and Tarceva, take advantage of the biologic differences between cancer cells and healthy cells by "targeting" faulty genes or proteins that contribute to the growth and development of cancer. Many times these drugs are combined with chemotherapy, biologic therapy (immunotherapy), or other targeted treatments.

Clinicians have learned that the same enzymes and pathways are involved in many types of cancer. However, understanding targeted treatments begins with understanding the cancer "cell." In order for cells to grow, divide, or die, they send and receive chemical messages. These messages are transmitted along specific pathways that involve various genes and proteins in the cell.

Cancer cells often have many mutations in many different pathways, so even if one route is shut down by a targeted treatment, the cancer cell may be able to use other routes.

Targeted therapies are typically not very effective when used singularly or even in combination with conventional chemotherapies. The targets of many of these drugs are so narrow that cancer cells are likely to eventually find ways to bypass them.

Physicians may have to combine several targeted treatments to try an achieve cures or durable responses for more complicated tumors like those that occur in the breast, colon and lung.

These targeted therapies produce limited results because they can help a relatively small subgroup of cancer patients. But when they work, they produce very good responses. With targeted therapy, the trick is figuring out which patients will respond. Tests to pinpoint those patients cannot be accomplished with genetic testing.

All the gene amplification studies, via genetic testing, tell us is whether or not the cancer cells are potentially susceptible to a mechanism/pathway of attack. They don't tell you if one drug (Iressa) is better or worse than another drug (Tarceva) which may target a certain mechanism/pathway. Cell-based functional analysis can accomplish this, or the physician can "trial-and-error" what will work. That's up to the patient.

The cell is a system, an integrated, interacting network of genes, proteins and other cellular constituents that produce functions. You need to analyze the systems’ response to drug treatments, not just one target or pathway, or even a few targets/pathways.

Literature Citation:

Functional profiling with cell culture-based assays for kinase and anti-angiogenic agents Eur J Clin Invest 37 (suppl. 1):60, 2007

Functional Profiling of Human Tumors in Primary Culture: A Platform for Drug Discovery and Therapy Selection (AACR: Apr 2008-AB-1546)

[RandyW]

Thanks Greg!!

[gpawelski]

Randy, how's your dog Mocha doing? I just lost my second best friend in life, Chessie (maincoon cat), yesterday. He came into my life eight months after my wife's demise. Trying to help cancer patients and their loved ones on the internet and loving this feline was what kept me alive all these years. Now he's gone too.