ReutersThe office of Swiss drug manufacturer Novartis in Basel, Switzerland.

NEW DELHI —Lawyers fighting against a Swiss drug manufacturer’s effort to patent an amended version of a cancer drug expressed relief on Monday after India’s highest court rejected the patent, in a case that has been closely watched by pharmaceutical companies, makers of generic drugs and health care activists.

“We’re very happy. A seven-year battle is over,” Anand Grover, a lawyer who had been arguing the case on behalf of the Cancer Patients Aid Association, told India Ink. “The drug is not novel, it’s not inventive.”

The ruling, which allows Indian makers of generic drugs to continue making cheap versions of the Novartis drug Gleevec, also known as Glivec, helps maintain India’s position as the largest exporter of generic drugs.

The Supreme Court’s landmark decision was welcomed by health care nonprofits, who said it would mean that medicines would be more affordable to poor patients in India and other developing countries.

The case represents a high-stakes showdown between defenders of intellectual property rights, who say generic versions stifle innovation by drug makers, and Indian drug companies and international aid groups, who warned that a ruling in favor of Novartis could have dried up the global supply of inexpensive medicines to treat AIDS, cancer and other diseases.

Indian patent law prohibits a newer form of a known substance from receiving a patent unless it significantly improves the medicine’s efficacy. The standard is aimed at preventing a practice known as evergreening, in which a pharmaceutical company makes minor changes to an existing drug to gain a new patent, and many more years of protection from generic competition.

“It’s a new form of an old substance, and that’s what the Supreme Court has upheld,” said Mr. Grover, the Cancer Patients Aid Association lawyer.

Gleevec, a cancer treatment heralded as a breakthrough for people with a deadly form of leukemia, can cost each patient up to $70,000 per year. Indian generic versions cost only about $2,500 a year.