overall, i think it's a bullish sign. Someone's on the other side of those trades, but could be someone unloading risk of previously purchased shares in addition to those writing.
Basically, the purchase of those calls, representing 30K in share, thinks that the price between now and May will hit at least 7.50+. Actually, to make any money, they would need the stock price to go a buck or two higher than that.
While bullish, it only cost them about $6K, so not a huge position. What they are buying a larger than usual run-up into ASCO + very the release of very exciting abstracts that have been accepted for presentation.
I made a similar bet, with calls expiring post-ASCO, as I'm hoping for positive results wrt 184. My enthusiasm is tempered, by the fact that management was similarly upbeat last year but released only mediocre data (as outlined by Oncodoc a few times here previously).