Five Prime Tanked on Early Peek of Lead Drug Data

Five Prime Therapeutics stock took a beating after it unintentionally released Phase Ia/Ib clinical trial of its CSF-1R antibody cabiralizumab with Bristol-Myers Squibb's Opdivo (nivolumab). Shares dropped as much as 41 percent, although it has rebounded some in premarket trading. Shares are currently trading at $30.02.

The company submitted an abstract ahead of the Society for Immunotherapy of Cancer (SITC) meeting that provided data on a small sample of pancreatic cancer patients that were treated with cabiralizumab and Opdivo. SITC published the data online head of the meeting. It showed an objective response rate of 10 percent, with three partial responses. There was a six-month disease control rate of 13 percent. John Carroll, with Endpoints News, writes, “But the backlash also centered on the troubling safety data among 205 patients with solid tumors, with a 43 percent rate of Grade 3 to 5 (death) adverse events in the study which triggered a discontinuation rate of 13 percent.”

Bristol-Myers Squibb dropped $350 million in an upfront payment to Five Prime two years ago to have access to the company’s colony stimulating factor 1 receptor (CSF1R) antibody program, of which cabiralizumab was the lead product. Including various milestones, which now seems questionable, the deal could have hit $1.74 billion.

Eun Yang, an analyst with Jefferies, wrote in a note to investors, “While the data is not as strong as we like to see, this compares reasonably to chemo combo in 2L PC.”

Michael Schmidt, an analyst with Leerink, wrote, “That said, we think the safety profile disclosed in the abstract, including Grade 3-5 treatment-emergent adverse events (TEAE) see in 43 percent of patients needs to be better understood and could raise some investor questions until the full dataset is provided at SITC next weekend.”

For the most part, analysts are waiting for the weekend and the release of more data at the SITC meeting. Meanwhile, the company’s market cap dropped to about $747.41 million.

The company held a conference call this morning to discuss the results. Both companies noted their surprise—and likely dismay—that the conference published the abstract online ahead of the meeting, which they did not expect to happen. The company indicates it is actually excited about the data and had plans to present data on Saturday Nov. 11 at 4:30 PM ET.

“In short, I feel that SITC grossly mismanaged this process, which as we can see had dramatic impact on publicly-traded companies like Five Prime,” said Lewis “Rusty” Williams, the company’s founder, president and chief executive officer, in the conference call. “This disclosure took us and the market by surprise, and we’re concerned that the abstract, which was submitted in September, didn’t really provide an adequate representation of the data being presented. In all my years of submitting abstracts and publications to meetings, I’ve never seen anything like this, in my business experience or academic experience. I think something needs to change there.”

The company originally planned to have the conference call on Nov. 7, but an extended GlobeNewsWire outage prevented the press release from being issued until this morning.

Williams presented three key points. First, Five Prime and Bristol-Myers Squibb are pleased with the data. Secondly, Williams said, “We and BMS and our investigators are very encouraged by this data, and as evidence of that, BMS is expanding development of the combination in pancreatic cancer and plans to initiate a randomized Phase II clinical trial shortly in patients with advanced pancreatic cancer.”

Williams’ third point was, “The safety analysis included 229 cancer patients treated thus far in the study and preliminary data showed that the combination of cabiralizumab and Opdivo does have an acceptable safety profile. Importantly, there were three Grade 5 SAEs, but none were in the cabira-monotherapy arm. They were all in the cabira-Opdivo combination therapy group. The Grade 5 SAEs were of the type observed in with PD-1 inhibitors alone. None of these were in the pancreatic cohort.”