SRafiqueKadcyla – the ADC linked to Herceptin – is approved for use in HER2-positive breast cancer. Earlier this year, according to Roche’s pipeline, the company intended to file for regulatory approval of Kadcyla in HER2-positive advanced gastric and GEJ adenocarcinoma in 2015.

However, in breaking news this week it has been reported that Kadcyla has failed in the Phase III GATSBY trial where it was being positioned as a second-line treatment for gastric and GEJ adenocarcinoma.

Herceptin was the first targeted therapy approved in this indication after demonstrating efficacy in HER2-positive disease, where it has experienced strong uptake during the last decade. Following its success in advanced breast cancer, it was generally thought that Kadcyla would similarly show efficacy in HER2-positive gastric and GEJ adenocarcinoma, mirroring the Herceptin’s development pathway.

However, Kadcyla’s failure to meet its primary endpoint in the Phase III trial was not so surprising after primary research conducted by Decision Resources Group indicated that Kadcyla’s likelihood for success in this indication was tenuous.

Although early clinical data in gastric and GEJ adenocarcinoma were lacking, most thought leaders interviewed by Decision Resources Group earlier this year were only cautiously optimistic that Kadcyla would demonstrate an OS benefit compared with single-agent taxane therapy in the Phase III study:

  • “If Kadcyla demonstrates the same results that we have had in breast cancer patients, we will be very pleased. Probably this drug is going to have an important role in gastric cancer for HER2-positive patients.” —Oncologist, Spain
  • “I would say that the breast cancer data in general has affected my view of Kadcyla. I am hopeful to see similar benefits in gastric cancer although I’m almost certain that the benefit will be less.” —Oncologist, United States
  • “I expect that Kadcyla will offer a smaller improvement than seen in breast cancer; it’s going to be very close as far as a statistically significant benefit is concerned.” —Oncologist, United States

Furthermore, there was also some uncertainty among interviewed thought leaders over the level of survival benefit that Kadcyla would demonstrate:

  • “I suspect that Kadcyla is not going to offer a huge difference in the second line of treatment for gastric cancer. There’s some skepticism, but if it shows an advantage and it meets its end point, registration is quite possible. However, I’m not expecting the GATSBY study to show that Kadcyla makes a marked difference.” —Oncologist, United States

We currently await further details of the clinical data from the Phase III GATSBY study.

Further insight on Kadcyla and it’s clinical development for gastric and GEJ adenocarcinoma can be found in our 2015 report – Pharmacor: Gastric and GEJ Adenocarcinoma

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