BANGALORE, Dec 11 - Shares of Sunesis Pharmaceuticals Inc (SNSS.O) were up for the second day on Friday, after positive data from two clinical trials of its experimental cancer drug, Voreloxin, boosted investor confidence.

Sunesis shares had doubled to $1.39 Thursday and touched a high of $2.43 in Friday's session.

Cowen & Co analyst Craig Gordon attributed the gains on Thursday and Friday to investors speculating about a possible partnership on the drug and the positive data.

If you ask me for percentages, I think 60 percent to 70 percent of the spike is on the chances of a partnership and 30 percent to 40 percent is from the data, Gordon said.

Sunesis Pharmaceuticals' Chief Financial Officer Eric Bjerkholt told Reuters that the company was already in talks for a partnership.

We're exploring alternatives for funding for that (late-stage) trial, and partnerships is one of the alternatives that are being explored, Bjerkholt said.

And then, yes, the last alternative might be to sell the company, he added. Bjerkholt said he would not be able to comment on which option the company would prefer until the terms on the funding alternatives were available. Sunesis, which has $3.9 million in cash and marketable securities as of Sept 30, is already in talks with possible partners on the drug, or buyers.

The CFO denied commenting if the deal talks were with buyers or with potential partners.

One of the reasons we are attracted to discussing with partners is that there is a broader development plan than we could possible fund on our own, Bjerkholt said.

Cowen & Co's Gordon sees an upfront payment of between $50 million to $70 million on the drug, but does not rule out a possible acquisition of the company.

So with a partnership we can have a joint development plan that could hopefully include other indications, he added.

On Monday, Sunesis said the Phase Ib/II study of Voreloxin showed a preliminary median overall survival of 7.8 months in patients suffering from relapsed or refractory acute myeloid leukemia. The biopharmaceutical company also determined an optimum dose in a mid-stage study.

Sunesis shares were up 23 percent at $1.71 Friday afternoon on Nasdaq. (Reporting by Vidya L Nathan in Bangalore; Editing by Anil D'Silva)