We just got some interim data from ArQule, Inc. (NASDAQ:ARQL), and there looks to be a bit of confusion as to what the data actually says about drug in question, ARQ087, and its efficacy. Here’s a detailed look at what the data tells us, and what it infers about the drug’s prospects going forwards.

So, the drug. As mentioned, it’s called ARQ087, and it’s targeting an indication called intrahepatic cholangiocarcinoma, or bile duct cancer. It’s the second most common form of liver cancer (although this doesn’t mean its particularly prevalent, with an incidence rate of around 2000-3000 new diagnoses annually in the US) and has a really poor prognosis. There’s no real standard of care that extends survival significantly, and once diagnosed, it’s a case of trying to resect the tumor to alleviate symptoms, as opposed to improve survival time. Surgery comes first, then radiation and chemotherapy.

ArQule is trying to position its treatment as an alternative to current SOC, and perhaps more importantly, a treatment that actually improves survival rather than targets symptoms. So how does it work? The drug is a multi kinase inhibitor, designed to selectively inhibit what’s called the fibroblast growth factor receptor (FGFR). FGFR inhibition has long been a target in oncology, and the field has bred a bunch of trials in indications like breast cancer, bladder cancer and lung cancer. The reason it’s such a hot target is that in cancer cells, FGFR is overexpressed and over activated. It serves as a sort of on/off switch for cell proliferation, and goes unchecked in cancer cells, which leads to the excessive proliferation that is commonly associated with the disease.

ARQ087 is disrupts the proliferation by inhibiting the FGFR, and in doing so, can theoretically halt progression in tumors – specifically, in this instance, bile duct associated tumors.

What did the data tell us about the drugs performance? The trial is a phase I/II, and involves 21 patients – 14 of which had a mutation called FGFR2 and 7 of which didn’t. The data released relates to the 14 that had the mutation, as these are the target based on a hypothesis that the mutation is the root cause of the cancer. Of the 14 with the mutation, 12 were evaluable (we don’t have any word on why the other 2 weren’t, but it’s likely not relevant).

It is these 12 that form the basis of the data presentation.

Of the 12, 3 recorded an objective response (defined as a partial response in the data). 3 others recorded a minor response. Disease control, defined as no tumor growth across a 16-week period, was recorded by 6 patients. The release that accompanied the data stated a 75% disease control rate, so where does this number come from? The company has combined the objective response number and the disease control number, to get 9 patients (75% of 12).

In layman’s, what does this say about the drug? Well, the numbers are enough to justify clinical efficacy, but just how well the drug works is still very much open to debate. A disease control rate of 75% is good for such a tough cancer to treat, but with only 3 out of the 12 showing any sort of objective response, and with this response being only partial at best (the low end of this category could mean the tumors resected by just 30%) then we can’t really say the data is a solid indication of efficacy.

That aside, the primary endpoint is safety. On this benchmark, ArQule reported that the majority of adverse events were grade one or grade two, which suggests the drug is reasonably well tolerated, albeit across a small population.

The bottom line is this: it’s a phase I/II, and the point of this data was to evaluate whether the trial should move from the former to the latter. It has, and so ArQule must believe that the findings warrant further investigation. That said, it’s very much in the company’s interests to continue through to the latter part of the trial, and so we can’t use this as a sole indication of the drug’s potential. The data is OK, not great, but in a target indication like bile duct cancer, where treatment options are slim, OK might be enough to warrant a closer look.