PHILADELPHIA (NYTIMES) - Albert Innaurato, a playwright who enjoyed spectacular success for a time in the late 1970s, including having a play run on Broadway for more than four years, has died in Philadelphia. He was 70.

His cousin Stephen Paesani said Innaurato was found dead in his bed Tuesday, and had probably been dead for two days. The cause was not clear, Paesani said, but Innaurato had heart problems recently.

Innaurato's biggest hit, written while he was still in his 20s, was Gemini, a comic drama about a Harvard student who returns to his blue-collar Philadelphia neighbourhood for his 21st birthday and has to confront, among other things, his sexual orientation. It opened on May 21, 1977, at the Little Theater on Broadway and ran for 1,819 performances.

A few months before that, another of his plays, The Transfiguration of Benno Blimpie, had an acclaimed off-Broadway run at the Astor Place Theater.

Innaurato had only recently graduated from the Yale School of Drama, where his fellow students included Christopher Durang, Sigourney Weaver and Meryl Streep. If his career arc did not ultimately match theirs - none of his later work came close to the success of Gemini - his wit and dark humour in those early days were on a par with Durang's.

"They wrote comedy with all barrels blazing, especially Albert," Weaver said in a telephone interview Wednesday.

Innaurato was as fond of opera as he was of theatre, both writing about it and directing it. Most recently he had been reviewing opera for the online magazine Parterre Box. A writer visiting his apartment in Greenwich Village for a profile for The New York Times in 1977 - at the peak of Innaurato's theatrical career - found it almost unfurnished but full of records, most of them operatic ones.

"The character in Gemini who's always playing Maria Callas records - I think that was really autobiographical," Paesani said.

Albert Francis Innaurato Jr. was born June 2, 1947, in Philadelphia. His father, Albert, was a linotype operator; his mother, Mary, was a nurse. Paesani remembered that the family had a piano, which Albert began learning to play at 5.

He attended Temple University in Philadelphia and the California Institute of the Arts before being accepted into the Yale School of Drama in the early 1970s. There, he and Durang, who was in the same class, quickly found common ground: Both had attended Roman Catholic schools.

"As we were reading some of our work in class, it came up quite quickly that I was writing plays that often had nuns in them, and so was he," Durang said in a telephone interview. "But mine were very Irish nuns, and his were angry Italian nuns who beat people up." Durang had made an experimental film of sorts inspired by The Brothers Karamazov, the Dostoyevsky novel.

"I showed it to Albert," he recalled, "and it was very crackpot, and he liked it and said, 'We should write a musical together.'" What resulted was The Idiots Karamazov, a sort of musical fracturing of Dostoyevsky that begins with an 80-year-old woman in a wheelchair who has muddled memories of translating Russian works. In its very first staging, in 1973, Innaurato played that part. When the play had subsequent stagings at the drama school and then, in 1974, at Yale Repertory Theater, a young actress in the class behind the two authors', Streep, took the role.

"Albert and I were so unsavvy at this point that it never crossed our mind to see what the scenic designer was doing," Durang recalled. For one thing, the set did not have a door big enough for the wheelchair to fit through. For another, the stage was inclined, leaving Streep in danger of rolling away if the chair's brake should get bumped into the "off" position.

For Innaurato, it was a relatively short trip from those early efforts to the big time. In May 1976, "Benno Blimpie," about a man who eats himself to death, was staged in New York by the Direct Theater, and that December Playwrights Horizons presented "Gemini," with a cast that included Weaver.

"Innaurato's instrument is not a needle, but a cleaver," Mel Gussow wrote in reviewing that production of Gemini for The Times. "There is savagery in his humour that is, in a strange way, refreshing at the same time that it is terrifying." Gemini received two other productions, at the PAF Playhouse on Long Island and at the Circle Repertory Theater, before being mounted on Broadway. It is still one of the longest-running straight plays in Broadway history. It was also an early example of a mainstream work with a gay plot: The protagonist is being pursued romantically by a character named Judith but is more interested in her brother.

The play was made into a movie, Happy Birthday, Gemini, in 1980, and in 2004 Innaurato collaborated with Charles Gilbert on Gemini The Musical, which had its premiere at the Prince Music Theater in Philadelphia.

Innaurato's later plays included Passione, which went from Playwrights Horizons to a Broadway run that lasted only 16 performances in 1980, and Coming Of Age in Soho, which received a lukewarm review from Frank Rich in The Times when it was staged at the Public Theater in 1985. Rich called it "an honest rite of passage from which Innaurato can honourably move on." Among his most recent stage credits was the one-act play Doubtless, seen in 2014 at 59e59 Theaters in Manhattan.

While working intermittently in the theatre, Innaurato also pursued his love of opera, writing for Opera News and other publications and sometimes directing or acting as dramaturge. His opera reviews could be sharp-edged, like his assessment of a production of Le Nozze di Figaro at Opera Philadelphia in May.

"I only hope the standing ovation at the end of the performance was for Mozart's music," he wrote in Parterre Box, "and not for the mindless antics onstage. Figaro deserves better than to be treated like an episode of Keeping Up With the Kardashians." Innaurato leaves no immediate survivors.

If his writing could be caustic and his stage humour devastating, Weaver remembered a gentler side. She recalled performing a particularly weighty monologue while a student at Yale that was greeted with indifference by faculty members, whom she often found unsupportive.

"I remember Albert taking me aside and saying, 'This is the kind of work you should be doing,'" she said. "Albert's opinion meant a lot more to me than the teachers' did."