By Bill Berkrot

NEW YORK (Reuters) - New drugs from Bristol-Myers Squibb and Vertex Pharmaceuticals are selling fast out of the gate, and their recent share sell-offs provide investors with a new opportunity to profit from the medicines' bright futures.

Bristol's melanoma drug Yervoy and Vertex's hepatitis C treatment Incivek, as well as Amgen's Xgeva for preventing bone fractures in cancer patients stormed past early sales projections because they are simply too good to be ignored, industry experts said.

"Vertex doubled the cure rate and Yervoy is the only drug approved ever that improved survival in melanoma," said Mark Schoenebaum, an analyst for ISI Group. "It becomes immediately medically unacceptable to not use them in patients whom you are treating, and there's no debate around it."

"Xgeva is not quite as dramatic, but they did do a head-to-head trial with the current standard of care and they beat it," Schoenebaum added.

All three medicines are expected to generate eventual annual sales in excess of $1 billion, with some analyst estimates for Incivek running north of $3 billion.

All arrived to doctors and patients clamoring for new treatments, proving the value of innovative medicines as many drugmakers stand to lose billions of dollars of revenue as older products come off patent.

"They are all first in class drugs for diseases that have not been well treated prior. If companies can deliver drugs that deliver the goods they are going to be successful," said Les Funtleyder, portfolio manager for Miller Tabak & Co.

Bristol shares are off about 9 percent since a year-high on July 21, Amgen shares are down more than 17 percent since touching a year-high in mid-May and Vertex has fallen 25 percent since reaching a high in May just prior to Incivek's approval -- all dragged down along with broader market plunges.

Analysts believe there is money to be made betting on any of these companies, especially with shares in their current beaten down state.

Schoenebaum said Amgen was a bargain at its current price, and that the ease of tracking Incivek prescription growth makes Vertex attractive. His Amgen price target of $68 is well above the current share price of around $48, while his Vertex price target of $54 leaves room to grow from its current price of about $43.

"Bristol is clearly right now the best company within the U.S. large pharma arena," he added.

The most bullish Wall Street price targets see Amgen rising as much as 63 percent, Vertex nearly doubling and Bristol-Myers with room to grow by 47 percent, according to data compiled by Thomson Reuters.

GENUINE BREAKTHROUGHS

All three recently approved medicines soared past most initial Wall Street sales estimates in the second quarter, defying the typical slow launch for most new medicines.

"There are demographic trends that would suggest that these drugs are going to see more demand," said Funtleyder, who agreed that it was not too late to jump on the bandwagon.

In just its first five weeks on the market, Incivek sales reached $74.5 million.

"What this means is there are a lot of patients out there waiting for treatment with new hepatitis C drugs," Sanford Bernstein analyst Geoffrey Porges.

"This is a genuine breakthrough. It's dramatically altering the outlook for these patients and they're lining up at physicians' offices," Porges said.

Much the same can be said for Yervoy, which in March became the first FDA approved treatment to offer real hope to patients with the deadliest form of skin cancer.

Yervoy, which spurs the immune system to fight the cancer, posted sales of $95 million in its first quarter on the market, helping Bristol to a better-than-expected second quarter profit.

Xgeva, which offers potential for a better quality of life to advanced cancer patients in danger of serious bone problems, nearly doubled expectations in its first full quarter on the market and recorded $75 million in second quarter sales, sailing past analysts' average estimates of $66 million.

They stand in stark contrast to Dendreon Corp's year-old prostate cancer vaccine Provenge, which was approved with great fanfare but has yet to catch on with physicians. The company last week pulled its bullish 2011 sales forecast, saying doctors were balking at dealing with reimbursement for its high price tag.

While Amgen and Bristol are looking to their new drugs to help replace fading sales of older products or those about to face generic competition, Incivek is the first commercial product for far smaller Vertex. But the biotech company was well prepared for its foray into uncharted territory.

Two years prior to Incivek approval, Chief Executive Joshua Boger -- long the soul of Vertex and the visionary behind the medicine -- stepped aside to make way for Matthew Emmens, a sales savvy CEO with several drug launches under his belt.

"They are lucky to have him. He's got a very good track record," Funtleyder said of Emmens. "Drug development and drug sales are two different skill sets and not everyone has both."

That move, as well as the drug's superior efficacy, appears to be paying off. Early Incivek prescriptions are outpacing those for a similar new rival drug from Merck & Co by a rate of better than three-to-one.

Investors may also do well to get behind companies with a new class of drug for preventing blood clots and strokes in heart patients.

The first of the new blood thinners, Pradaxa, comes from privately held Boehringer Ingelheim. But demand for that drug -- more than 250,000 patients prescribed in its first seven months -- bodes well for others, including apixaban from Bristol and Pfizer that may prove to be superior.

(Reporting by Bill Berkrot, editing by Bernard Orr)