Cancer drug rivals at Loxo and Blueprint go toe-to-toe once again, and one analyst scores a (possible) win on points

Who’s ready to start the week comparing data on two rival cancer drugs from studies featuring different trial designs?

OK, I’ll do it anyway.

Loxo Oncology $LOXO and Blueprint Medicines $BPMC have been duking it out with their early-stage studies on their RET inhibitors, and they were both back at it with updates for mutant medullary thyroid cancer at the American Thyroid Association meeting over the weekend.

Andrew Berens

Leerink’s Andrew Berens scored the two latest snapshots on data, and I’ll let him do the summary. First, though, I’ll echo Berens’ note that the two drugs are not dosed the same way, with Loxo patients able to get a dose escalation during the study, while Blueprint is sticking with a fixed-dose study — which may put it at a disadvantage in terms of quick comparisons.

Purists in the field hate these trial comparisons, but investors eat them up.

That said, Loxo reported an updated ORR of 59% for LOXO-292, with 2 complete responses and 15 partials. The ORR is up from the 45% reported at ASCO while the 78% response rate seen for patients with a RET fusion thyroid cancer is down a bit. Still, the analyst notes, the update only accounts for 9 patients in total, so don’t try to read too much into that.

Blueprint, which has suffered before from the side-by-side pics with BLU-667, had a 49% response rate with 1 CR and 16 PRs. Berens: “Interestingly, responses appear to be deepening over time. ORR for patients treated at 300/400mg QD dose level was 35% at 8 weeks of treatment, 56% at 16 weeks and 62% at 24 weeks. Responses were equivalent in patients with and without prior multi-kinase inhibitor (MKI) treatment (~50%). 83% (35/42) of thyroid cancer patients remain on treatment, and 100% of responders (19/19) and those treated at 400mg QD (14/14) remain on therapy.”

Sure, says Berens, Blueprint may well feel some heat because its numbers still don’t measure up to Loxo — now partnered in a deal with Bayer — but he gives both drugs a thumbs up for improving response rates and impressive (early) signs of durability.

Did I say that this rivalry has a ways to run?

For now, the handicapping continues to favor Loxo, but this race isn’t over. Also, there’s nothing in the Blueprint numbers to suggest that they’re going to be forced out of the race, with good chances that both get through a well greased regulatory system — provided the data hold up.

Loxo also got bonus points at the ATA meeting. Berens notes that they have “updated data for larotrectinib in seven patients with TRK fusion thyroid cancer. Five of these patients had papillary disease, while one had follicular, and one had anaplastic disease. Six of the seven patients remain on therapy, with duration of treatment ranging from 12.9 months to 28.7 months.”

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Research Scientist - Immunology
Recursion Pharmaceuticals Salt Lake City, UT
Director of Operations
Atlas Venture Cambridge, MA

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