Poniard Drug Safe, Less Effective: BioBuzz - TheStreet

SOUTH SAN FRANCISCO, Calif. (

TheStreet

) --

Poniard Pharmaceuticals

(PARD)

said Sunday that its experimental chemotherapy drug picoplatin reduced the severity of nerve damage in patients undergoing treatment for colon cancer, meeting the primary goal of a phase II study.

And with that, Poniard shares should trade down Monday. I don't know what the stock will actually end up doing, but Poniard shares jumped 22% to $2.61 on extra heavy volume Friday as investors anticipated the picoplatin data.

That screams "sell on the news" to me, especially since nearly all of the data from this phase II study were

disclosed online

last Wednesday, Jan. 20. That left little to be surprised about Sunday for Poniard to disclose.

Picoplatin is a next-generation platinum chemotherapy drug designed to overcome resistance to prior platinum therapy and cause less neuropathy, or nerve toxicity.

Last November, however, picoplatin

failed a phase III study

in small cell lung cancer that was seen as the fastest and best way for the drug to reach the market. Poniard's

stock price plunged

on the negative results.

Sunday's positive safety data in colon cancer -- announced at the American Society of Clinical Oncology's (ASCO) meeting on gastrointestinal cancers -- may give picoplatin a new life (Poniard executives certainly believe so) but the drug's better side effect profile appears to be coming at the expense of efficacy.

Poniard downplayed efficacy results in Sunday's announcement because patients treated with oxaliplatin, the approved chemotherapy drug used as a comparator the study, reported more tumor shrinkage and lived longer than those treated with picoplatin.

Poniard called the efficacy of picoplatin and oxaliplatin statistically "similar" in the phase II study of 101 newly diagnosed colon cancer patients, but the actual numbers tell a different story.

The overall response rate to picoplatin (defined as patients reporting complete and partial tumor shrinkage) was 29% in the phase II study, compared to an overall response rate of 38% to oxaliplatin, according to a

research abstract

of the data.

Poniard said the "disease control rate" of picoplatin and oxaliplatin was 75% and 76%, respectively, but this definition of response makes picoplatin look better because it includes patients with stable disease, or tumors that neither shrank nor grew after treatment.

The efficacy of picoplatin also looked worse over time. Last May, when data from this same study were presented on an interim basis at the ASCO annual meeting, the response rate to picoplatin was 22% compared to 28% for oxaliplatin. So, in a year's time, the response rate delta between the two drugs has grown from 6% to 9%.

And yes, data from these study were known last year -- another reason why Sunday's announcement was less than a surprise.

Poniard did provide survival results Sunday for the first time, but again, picoplatin came up short. The median overall for picoplatin-treated patients was 13.6 months compared to a median overall survival of 15.6 months for oxaliplatin -- a difference of two months.

The reported progression-free survival (PFS) for picoplatin and oxaliplatin was 6.8 months and 7 months, respectively -- another efficacy measure that went against picoplatin. The PFS data Sunday were unchanged from what was reported last May.

Poniard says this phase II study was relatively small, with only 101 patients enrolled, and it was designed to assess safety and not efficacy. Therefore, none of the efficacy measures were statistically significant, which means it can't be definitively proven that picoplatin isn't as effective as oxaliplatin.

That's all true, but the results certainly suggest strongly that picoplatin has an efficacy problem. If this was a larger phase III study with more patients powered to detect statistical differences of efficacy between the two drugs, oxaliplatin could have easily come out on top.

Picoplatin does appear to cause less nerve toxicity overall. Neuropathy, regardless of grade, was 26% in the picoplatin arm compared to 62% in the oxaliplatin arm. No patients treated with picoplatin reported severe neuropathy.

However, picoplatin did cause higher blood-related toxicity, including fevers, infections and bleeding, compared to oxaliplatin.

Poniard said Sunday that the final results from this phase II study supports the company's assertion that picoplatin could one day replace oxaliplatin as the preferred platinum-based chemotherapy used to treat colon cancer.

Poniard wants to start a phase III study to advance picoplatin's development. The company is seeking a partner willing to help pay for the cost of the trial in exchange for marketing rights to the drug.

But with one failed phase III study under its belt already in small cell lung cancer and questions about its efficacy in colon cancer, how likely is it that a large drug company will want to take on the expense and risk of developing picoplatin, especially since oxaliplatin is now generic and relatively inexpensive?

-- Reported by Adam Feuerstein in Boston.

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Adam Feuerstein writes regularly for TheStreet.com. In keeping with TSC's editorial policy, he doesn't own or short individual stocks, although he owns stock in TheStreet.com. He also doesn't invest in hedge funds or other private investment partnerships. Feuerstein appreciates your feedback;

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