Loxo, Bayer maintain 90%-plus response rate in cancer trial

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All but one of the 17 TRK fusion cancer patients in the trial remain on the drug or have undergone surgery intended to cure them.

Bayer has shared results showing why it was willing to spend big on Loxo Oncology’s larotrectinib. The latest data drop shows 94% of children with advanced solid or primary CNS tumors remain on the oral TRK inhibitor.

Loxo shared a look at data from the trial earlier this year, at which point the biotech had data on 13 of the 17 patients with TRK gene fusions to enroll in the phase 1. Back then, 12 of the 13 patients appeared to have responded to larotrectinib, although Loxo was waiting on confirmatory scans for two participants. That gave the trial a provisional overall response rate of 92%

Now, Loxo has released a top-line look at the latest data, revealing the ORR has ticked up by one percentage point. That suggests the previously pending scans confirmed the provisional responses. And that Loxo has seen a positive response from one or two of the previously nonevaluable kids.

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All but one of the 17 TRK fusion cancer patients in the trial remain on the drug or have undergone surgery intended to cure them. Loxo now has more than a year of follow-up data on four subjects and more than six months of results on 12 participants, bolstering its belief in the durability of the patients’ responses to its drug.

Loxo will share more of the results in a poster at the American Association for Cancer Research Special Conference on Pediatric Cancer Research today.Publication of the data comes three weeks after Bayer acquired the rights to larotrectinib and follow-up candidate LOXO-195 in a deal expected to cost it $1 billion over the next few years. That deal followed the release of data from the phase 1 trial and other studied, which showed the lead drug is effective in most patients with TRK fusion-positive cancers.