The latest update for Nektar's immuno-oncology asset NKTR-214 given in combination with Bristol-Myers Squibb's Opdivo showed a drop in response rate for three cancers compared to an earlier readout in the fall. Nektar shares fell 5% Wednesday evening before perking back up 3% in premarket trading.
The phase 1/2 Pivot study is investigating the NKTR-214/Opdivo combination in melanoma, kidney cancer, non-small cell lung cancer (NSCLC), triple-negative breast cancer and bladder cancer. In an abstract released ahead of next month's ASCO meeting, the overall response rates for the first three declined.
For melanoma, the response rate of 23 patients was 52%, compared to 63% of 11 patients reported in November. In 24 patients with renal cell carcinoma, the rate was 54%, compared to 71% of 13 patients. And in six patients with NSCLC, the rate was 50%, compared to the 75% recorded for four patients in the fall.
The data is current as of Feb. 7—to meet ASCO's abstract deadline—and includes 60 patients. Jefferies analysts said the data doesn't paint the full picture for the combination therapy, calling it "stale" and saying "fresher" data is on its way.
"In fact, management on the 4Q17 conference call had highlighted a further deepening of the patient response rates, with ORRs at 64% for first line melanoma, 71% in first line RCC, and 60% in first and second line NSCLC," they wrote in an investor note. "Importantly, the full ASCO data set will include 100+ IO-naïve patients."
As for the remaining two cancers, the numbers are still preliminary. The company has data for only three triple-negative breast cancer patients and four patients with bladder cancer, with response rates of 75% and 33%, respectively.
"While very early, we view these as positive starting points for the new indications and a particularly positive starting point for use in bladder cancer," the analysts wrote. "While the duration of therapy was not available in the abstract, these patients likely had only been on drug for several months by last February when the data were submitted to ASCO for consideration. Thus, as with the other indications, we look forward to the additional data to be published at the conference and note the historical tendency for patients’ responses to deepen over time."
Nektar and Bristol-Myers first teamed up on a series of combination trials in September 2016, just after Opdivo failed a phase 3 trial in NSCLC. In February, the Big Pharma committed up to $3.6 billion to develop NKTR-214 in combination with Opdivo and Yervoy. It ponied up $1 billion up front, bought $850 million in Nektar stock and promised a potential $1.8 billion in milestones.