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to the toxin, stands to collect a “mid-single digit” percentage royalty on worldwide sales if T-DM1 is turned into a marketed product, and it hopes the drug will validate other similar treatments it has in its pipeline.
Roche’s Genentech unit has said it might seek FDA approval if the results are compelling from this latest trial, although Genentech spokeswoman Krysta Pellegrino stopped short of promising that the company will file its application right away. “Genentech will discuss next steps with the FDA. It is too early to determine if we will submit these data to the FDA, or what type of review would be granted,” she said in an e-mail.
But the evidence is starting to mount in T-DM1’s favor. Today’s findings of tumor shrinkage in one-third of patients were verified by an independent review panel, which is generally considered more reliable than reports from investigators. When the independent panel looked at clinical benefit, by adding cases of tumor shrinkage to the number of patients who had stable tumors for at least six months, then about 44.5 percent of patients appeared to benefit.
That finding builds on a separate study from earlier this year of 112 patients. About one in four patients experienced tumor shrinkage, according to data presented at the American Society of Clinical Oncology meeting in late May. Roche is also conducting a pivotal trial of 580 patients that began in February.
There are plenty of questions reviewers could ask about the results of this latest study coming out today in San Antonio, and whether it offers convincing enough evidence for the treatment.
Although this is often the case for clinical trials in severely ill cancer patients, there was no control group or placebo group in this study of 110 patients, so it’s impossible to say with certainty how well this performance compares with any other treatment. While tumor shrinkage was the primary goal of this study, and it can sometimes be a promising indicator that a drug will help patients live longer, it isn’t always reliable, because tumors can sometimes bounce back quickly and kill patients. More of the patients will need to be followed up for a longer period of time through an important measurement known to regulators as “progression-free survival” before anyone can say how long T-DM1 is really able to keep tumors from spreading.
One patient in the study who had liver disease ended up dying of liver failure, although researchers didn’t consider that event related to the T-DM1. Researchers didn’t see any severe cases of heart damage in patients taking the drug, which is noteworthy because that’s the kind of side effect that can derail a cancer drug, and it has been reported in a limited number of patients who take the traditional form of trastuzumab.
The full data are being presented today in San Antonio by lead investigator Ian Krop of the Dana-Farber Cancer Institute. In a statement from Genentech, he called the findings of the new trial “significant.”
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