Novartis claims India's laws are unfair because they currently allow Indian firms to manufacture far cheaper imitations of products which Novartis designed.
Al Jazeera's correspondent in India said: "Right across the developing world, people suffering from life-threatening diseases like cancer and HIV are dependent on generic drugs like these manufactured in India, for their very survival.
"At $100 or more a month, even now, these drugs are barely affordable.
"But if companies like Novartis were to win their case, then it would simply be out of the question."
Non-governmental organisations fear a victory for Novartis could set a precedent for other pharmaceutical companies seeking patent protection for essential medicines.
New and improved
India's patent law, which came into effect on January 1, 2005, allows patents for products that represent new inventions after 1995, the year India joined the World Trade Organisation, or for an updated drug that shows greater efficacy.
"Our case is solely about safeguarding intellectual property, this is not about patient access."
Novartis insists that its improved drug is more easily absorbed by the body.
But Indian drug companies and aid groups say Gleevec, which is known in Europe and India as Glivec, is a new form of an old drug invented before 1995.
Several Indian pharmaceutical companies already make generic copies of Gleevec, but sell it at a tenth of the $2,600 price for a monthly dose charged by the Swiss company.
Novartis says it has a record in funding health care projects for the poor which cost it hundreds of millions of dollars.
In a statement, the company said: "Our case is solely about safeguarding intellectual property. This is not about patient access. With our well-regarded record in social responsibility, we are surprised that some groups are confusing the issue in India."
But health campaign groups say that if drug companies like Novartis are allowed to patent their products, cheap copies will dry up, and the poor will go untreated.
Leena Menghaney of Medecins Sans Frontieres, an international aid group, said the impact of the case could affect patients across the developing world.
Menghaney said: "India is a very key source for patients in the developing world, it's what we call the pharmacy of the developing world. That's why we're asking Novartis, because of the public health impact, to please withdraw its case."
The group, along with Oxfam, has so far collected 250,000 signatures for a petition to Novartis asking it to drop its case.
|Activists say a change in drug patent law|
could leave millions without treatment [AFP]
Campaigners are also looking to the Indian government for help and sympathetic politicians say patent laws simply should not apply to drugs at all.
Nilot Palbasu, an Indian legislator said: "This is at the core of the conflict between the people’s movement, between the governments of the developing countries and those of the developed ones, on the question of whether intellectual property regime would help and abet global corporations to earn super profit."
Novartis has defended its position and said it will offer its leukaemia drug for free to patients who cannot afford it, even if it wins the case.
Paul Herrling, head of Novartis's corporate research, said: "We don't fight for Gleevec, we fight for the principle."
Other drugs companies which have similar cases lined up are keenly watching the outcome.
Source: Al Jazeera and agencies