Shares of MacroGenics went stratospheric Wednesday following the release of data from a pivotal Phase III study of the company’s lead drug candidate in breast cancer that beat many investors’ expectations.
Rockville, Maryland-based MacroGenics said the Phase III SOPHIA study comparing margetuximab against Roche’s Herceptin (trastuzumab) in HER2-positive metastatic breast cancer had met its primary endpoint of extending progression-free survival. The company’s shares on the Nasdaq opened 166.4 percent higher than their Tuesday closing price, skyrocketing from $11.11 per share to $29.60. As of early Wednesday afternoon, they were still up more than 123 percent.
In a conference call to discuss the results Wednesday morning, some analysts conceded that their forecasts of SOPHIA being a negative study did not come true, including one who said his firm was “dead wrong.”
Nevertheless, the company is being tight-lipped at the moment about a key data point, the exact improvement in PFS for SOPHIA’s margetuximab arm over the Herceptin arm. It is also not providing details the trial’s median overall survival.
In a conference call Wednesday morning, CEO Scott Koenig fended off questions from analysts pushing him to give more clues about the median PFS, saying the company would present the data at an upcoming scientific conference. Near-term oncology conferences include the American Association for Cancer Research’s meeting in Atlanta next month and the American Society of Clinical Oncology’s meeting in Chicago in June. Pressed for more details about PFS, Koenig only said those data are “looking good.”
As for OS data, he said not enough deaths have occurred in the study to provide a measurement of OS, but expects the company will have those data available early next year. The company said it plans to file for Food and Drug Administration approval in the second half of this year. However, approval from the European Medicines Agency will likely require the company to have OS data, Koenig said on the call.
SOPHIA randomized 530 patients to receive either margetuximab with chemotherapy or Herceptin with chemotherapy. MacroGenics said patients in the margetuximab arm saw a statistically significant 24 percent risk reduction in PFS compared with those in the Herceptin arm. Additionally, 85 percent of patients in the study carried the CD16A 158F allele, which is associated with diminished clinical response to Herceptin, but those in that group who received margetuximab also saw a statistically significant 32 percent PFS risk reduction. Currently, several biosimilar versions of Herceptin have FDA approval.
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