* EU agency to decide on olaparib in ovarian cancer next week

* AstraZeneca sees drug as potential $2 bln-a-year seller

* Expectations rising for company's cancer drug pipeline

By Ben Hirschler

LONDON, Oct 14 (Reuters) - AstraZeneca's cancer drug pipeline, already on a roll following promising clinical trial results, could get a further boost next week from a European green light for an experimental medicine against ovarian cancer.

European Medicines Agency experts will consider whether to recommend approval of olaparib at their regular monthly meeting, with a decision expected on Oct. 23 or 24, a company spokeswoman said.

A positive decision would be a fillip for a product that AstraZeneca has flagged as a potential $2 billion-a-year seller but which hit a road bump in June when a U.S. panel voted against its accelerated approval.

Olaparib blocks an enzyme involved in cell repair and is designed for patients with certain hereditary gene mutations. It also has promise in treating breast and gastric cancers, opening up a substantial market opportunity.

In addition, it is being tested in combination therapy, an approach widely seen as the future of cancer treatment because of the need to fight tumour cells on several fronts.

Cancer medicine is central to AstraZeneca's claims that it has a strong independent future, after fending off a $118 billion takeover bid from Pfizer in May.

As part of its defence, the British drugmaker set out a bullish set of forecasts for its drug pipeline and predicted that group sales would climb 75 percent by 2023.

While still seen as ambitious, that upbeat assessment is beginning to win over more analysts as the company makes good progress in its drug development programmes.

Bank of America Merrill Lynch was the latest to trumpet AstraZeneca's drug pipeline on Tuesday, following a glowing report on its cancer medicines from Jefferies a day earlier.

Most interest is focused on the company's rapidly developing line-up of experimental immunotherapy treatments, which boost the immune system's ability to fight cancer. Research presented at a cancer congress in Madrid last month suggests AstraZeneca is in a strong position in this field.

Bank of America analysts said the drugmaker's "dramatic pipeline progression" had prompted them to increase peak risk-adjusted sales forecasts by $16 billion in the past 12 months.

A recent move by the U.S. Treasury to curb "inversion" deals that allow firms to escape high U.S. taxes by reincorporating abroad has recently deflated expectations of a renewed Pfizer bid and Bank of America sees only a "low probability" of a deal.

Jefferies, however, believes AstraZeneca remains one of the more viable inversion targets that Pfizer could contemplate.

(Editing by Pravin Char)