Prime time for Five Prime as Amgen snaps up this once-moribund biotech for $1.9B and its phoenix-from-the-flames cancer asset

After seeing the biotech's shares soar 300% late last year on positive new data for its midstage gastric cancer program, Amgen has stepped in with a $1.9 billion deal to buy out long-suffering Five Prime Therapeutics.

That drug, bemarituzumab, has been through a phase 2 trial as a front-line treatment in patients with advanced gastric and gastroesophageal junction cancers, with make-or-break data out last November.

The readout broke down like this: Investigators enrolled 155 people with FGFR2b-positive tumors, a subpopulation that accounts for 30% of all non-HER2-positive patients, and randomized them to receive bemarituzumab or placebo on top of chemotherapy.

The trial cleared the pre-specified bar for statistical significance against all three efficacy endpoints, although the p-values were higher than the 0.05 that typically serves as the cutoff for effectiveness.

Progression-free survival in patients who received bemarituzumab on top of chemotherapy was 9.5 months, more than two months longer than the figure in the control arm. The difference worked out at a p-value of 0.073 and a hazard ratio of 0.68. Ahead of the data readout, Five Prime Chief Medical Officer Helen Collins, M.D., told investors previously successful gastric cancer trials achieved hazard ratios of around 0.7.

As of the cutoff, Five Prime was yet to reach the median overall survival in the bemarituzumab arm. The median overall survival in the control group was 12.9 months, leading Five Prime to calculate the hazard ratio at 0.58. Roche’s Herceptin and Bristol Myer Squibb's Opdivo, respectively, drove 2.7 and 3.3 month improvements in overall survival, resulting in hazard ratios of 0.74 and 0.71. Five Prime also saw improvements in response rate that are in line with the results achieved by both pharmas' drugs.

The drug certainly still has much to prove, and safety concerns to overcome. But the data, as complex as they were, still saw its shares jump omn the readout in November last year by 300%, and made it an attractive buyout option for a big company, which has turned out to be Amgen. It nabs the biotech for $38 per share in cash, or around $1.9 billion, a major 78% premium over its $21 close yesterday.

This is also a major leap from the around $5 a share it was trading at before the bemarituzumab data came out. The drug is partnered with Chinese company Zai Lab, though Amgen can nab royalties on China sales.

RELATED: After swinging the ax on staffers, Five Prime Therapeutics loses CEO

Gastric cancer is the third most-common cause of cancer death globally, and patients have suffered from a dearth of new drugs. It is now more than a decade since the FDA approved a new front-line treatment, and chemotherapy remains the standard of care for most HER2-negative patients. Five Prime and now Amgen want to change that and will prep for phase 3 trials.

Five Prime also believes FGFR2b “could play a role in other epithelial cancers, including lung, breast, ovarian and other cancers,” indicating attempts at a broader plan for the drug.

Amgen will get its earlier pipeline work as well, which includes one phase 1 CD80-Fc fusion asset and several other preclinical drugs. 

“The acquisition of Five Prime offers a compelling opportunity for Amgen to strengthen our oncology portfolio with a promising late-stage, first-in-class global asset to treat gastric cancer,” said Robert Bradway, chairman and CEO at Amgen.

“We look forward to welcoming the Five Prime team to Amgen and working with them to leverage our best-in-class monoclonal antibody manufacturing capabilities to supply additional clinical materials, as well as expanded production quantities, to realize the full potential of bemarituzumab for even more patients around the world as quickly as possible.”

This is also the biggest buyout deal for Amgen since it bought out Onyx Pharma all the way back in 2013 (which turned out to be a dud) and adds to its attempts for a cancer pipeline, which currently centers on its KRAS hopeful in lung cancer. In recent years it has also bought arthritis med Otezla from Celgene/BMS for $13.4 billion, and penned a BeiGene collab for $2.7 billion for a 20.5% stake in the company, and a deal to sell cancer meds in China.

“This is an exciting day for patients who may one day benefit from the promise of bemarituzumab and our full pipeline. I’m so proud of the Five Prime team and the science we’ve pioneered,” added Tom Civik, president and chief of Five Prime.

“We see tremendous complementarity between the two companies. Amgen has global reach, world-class resources, and they share our deep passion for science and commitment to patients. I have full confidence that Amgen is the right company to work with us to bring our innovative cancer treatments to patients and to achieve our mission to rewrite cancer.”

This is a positive end to the biotech’s life as an independent company, and one that not so long ago seemed impossible. In 2019, it cut 20% of its staff, then lost its CEO. At the time, it also said: “The company will retain a small research group focused on advancing three wholly-owned, late-stage research assets and will increasingly rely on outsourcing and contracted capabilities.”

This came two years after the company jettisoned a $460 million-plus alliance with InhibRx, saying it made the move to maintain a tight focus on priority programs that it can bring forward quickly.

Things then got worse: Just over a year ago, a key clinical trial that was a big part of a more than $1 billion partnership between Bristol Myers and Five Prime also flopped. This was for its other pipeline hopeful, cabiralizumab, which was wedded to BMS’ cancer immunotherapy drug Opdivo (nivolumab), with or without chemotherapy, in patients with advanced pancreatic cancer.

It failed to meet its primary endpoint of progression-free survival, and Bristol all but walked away from trials with the biotech’s drug.

The bemarituzumab data have proved to be the phoenix from the flames for Five Prime as it becomes subsumed into Amgen.