3 Clinical Trials with Mixed to Disastrous Results: Sophiris, Merrimack and Pfizer

Clinical Trial Halt

Although it’s great to report on successful clinical trial results, the reality is that only about one in 10 drugs make it to approval. With that number in mind, here are a couple companies reporting problematic clinical trials today.

Sophiris Bio. Headquartered in San Diego and Vancouver, British Columbia, Sophiris Bio today announced top-line interim safety and biopsy data from its ongoing open-label, Phase IIb clinical trial of topsalysin (PRX302). The drug is a first-in-class, pore-forming protein being evaluated for urological diseases. On the positive side, a single dose of the drug showed an ability to ablate targeted prostate cancer cells with 29 percent of patients showing a clinical response, with six patients showing a complete ablation with no detectable cancer on targeted biopsy of the treated area.

The downside is a big downside. The company reported a patient death on the same day as their second administration, causing the company to halt the second administration in any other patients. So far, over 450 patients have received a single administration of the drug at various doses. The company says it plans to investigate the cause, but no new safety signals have been reported.

“We are extremely saddened by the death of a patient after receiving a second administration of topsalysin,” said Randall Woods, Sophiris’ president and chief executive officer, in a statement. “Understanding the cause of the patient’s death is our first priority and essential to determining the potential for re-administration of topsalysin in future clinical trials.”

Although it’s not clear at this time if the drug is the result of the patient death, or even released what the cause of patient death was, company shares dropped almost 44 percent at the news.

Merrimack Pharmaceuticals. Based in Cambridge, Massachusetts, Merrimack announced top-lien data from its CARRIE Phase II trial of MM-141 (istiratumab) in patients with previously untreated metastatic pancreatic cancer and high serum levels of free Insulin-like Growth Factor-1 (IGF-1). The trial failed to meet its primary or secondary efficacy endpoints in patients receiving the drug in combination with nab-paclitaxel and gemcitabine compared to nab-paclitaxel and gemcitabine alone. Although it phrased it a bit oddly—“Merrimack will not devote additional resources to the development of MM-141”—the company is abandoning the program and focusing its attention on other programs in its pipeline.

Shares in the company dropped 23.5 percent in premarket trading.

Pfizer. Pfizer announced overall data from its Phase III PALOMA-3 clinical trial of Ibrance (palbociclib) in combination with fulvestrant compared to placebo plus fulvestrant in hormone receptor-positive (HR+), human epidermal growth factor receptor 2-negative (HER2-) metastatic breast cancer in patients whose disease has progressed after prior endocrine therapy. The trial met its primary endpoint of progression-free survival (PFS), both statistically significant and clinically meaningful improvement in the Ibrance-chemo group compared to the placebo plus fulvestrant group. Although the results showed a positive trend in the hazard ratio favoring the Ibrance combination, it was not statistically significant. A secondary endpoint was overall survival, but didn’t hit statistical significance there, either, although the company noted that “the trial design was not optimized to detect a statistically significant difference in OS.”

“While the difference in overall survival narrowly missed the threshold for statistical significant—a high bar for any trial in this patient population—it is similar, in absolute terms, to the improvement in median progression-free survival previously demonstrated in this trial,” said Mace Rothenberg, chief development officer, Oncology, Pfizer Global Product Development, in a statement. “We are encouraged by these results, which build on the compelling clinical benefit delivered by Ibrance. Ibrance in combination with endocrine therapy has transformed the treatment landscape for patients with HR+, HER2- metastatic breast cancer.”

The drug is already a blockbuster and brought in $933 million in the first quarter of this year. Pfizer indicated it plans to present detailed trial data at an upcoming medical conference.

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