Roche Holding AG on Monday extended its $5.7 billion cash bid for U.S. gene decoder Illumina for a second time as the Swiss drug maker sticks to its tried and tested M&A strategy.

Roche is offering $44.50 per share for Illumina, but analysts expect the company to ultimately raise its offer for San Diego-based Illumina, whose shares closed at $50.46 on Friday.

The Basel-based company extended its offer until 6.00 p.m. New York time on April 20.

Roche urged Illumina shareholders last week to take up its offer, which it views as full and fair, but which has been dismissed by Illumina as too low.

Roche, the world's largest maker of cancer drugs, has already extended its offer for Illumina once as it digs in and plays a waiting game before possibly stepping in with a higher offer, a strategy that has paid off in the past.

The group took seven months to buy U.S. diagnostic test-maker Ventana for $3.4 billion in 2008. It first made an unsolicited, low-end bid before increasing its original offer by 19 percent.

Illumina makes machines that decode a person's entire genome and would give Roche a leading position in the market for gene sequencing, which can help better identify which patients benefit from a given drug.

Roche has been pushing ahead in developing targeted therapies and Illumina's technology would help it to progress further in this field as gene sequencing is central to personalised medicine, particularly in cancer.

Roche is hoping to gain a majority on Illumina's board at its annual general meeting on April 18.

(Reporting by Caroline Copley. Editing by Jane Merriman)