Summary
- Athenex reported positive results in a phase 3 study using oral paclitaxel to treat patients with metastatic breast cancer.
- The key advantage of the company involves its orascovery platform which utilizes an inhibitor of P-glycoprotein known as enciquidar, which allows chemotherapy to be given in oral form.
- There was an improvement in safety. This is noted in the released safety data showing 17% of oral paclitaxel patients having neuropathy as opposed to 57% for those on placebo.
- The orascovery platform is not just being applied to paclitaxel, it can be used on all other types of chemotherapy like irinotecan, topotecan, docetaxel and eribulin.
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Athenex (ATNX) reported positive results from its phase 3 study using oral paclitaxel to treat patients with metastatic breast cancer. What makes this biotech good for the long term is that it has just proven that one of its clinical products works in improving clinical outcomes and provides a more convenient option for patients. It still has a pipeline full of other clinical products that don't use the same type of orascovery technology, which diversifies the pipeline. With this positive data on hand and the primary endpoint being met, the company will move expeditiously to file an NDA for potential FDA approval of oral paclitaxel. The NDA filing itself and then possible approval will both act as major catalysts for Athenex.
Phase 3 Study Meets Goal Of Providing New Treatment Option For Standard Of Care
The phase 3 study recruited a total of 402 patients with metastatic breast cancer. Patients were either given oral paclitaxel or IV paclitaxel. The primary endpoint was overall response rate (ORR) confirmed at two consecutive timepoints. This was measured using RECIST v1.1 criteria. The final outcome was that oral paclitaxel had an ORR of 36% compared with IV paclitaxel with only 24%. That is, oral paclitaxel achieved a statistically significant outcome over IV paclitaxel with a p-value of p=0.01. Based on the cut off date as of July 25, 2019, there were strong trends in other endpoints such as progression-free survival (PFS) and overall survival (OS). However, these endpoints have not yet reached statistical significance. The p-values for PFS and OS are p=0.077 and p=0.11, respectively. I believe the same thing which the biotech believes, in that this data was just too early at the cut off date to reach statistical significance for these two specific endpoints. In addition, there is still plenty of time until trial completion to reach statistical significance in both of these endpoints. Especially, if you consider that there is still a trend in both of them improving. What I found to be crucial in the released data is that there is a sharp advantage for oral paclitaxel. This is the basis that for a certain amount of patients that responded to this type of treatment of over 150 days, it was shown to be 2.5 times higher in response compared to IV paclitaxel. I believe such a duration of response for oral paclitaxel should be highly welcomed. A patient that continues with a duration of response for a longer period of time won't relapse in their cancer as quickly.
Competitive Advantage Over Existing Anti-Cancer Agents
All of this clinical data is good, but why is it important for patients to take oral paclitaxel over IV paclitaxel? Besides the improved clinical data I highlighted above, it all boils down to poor oral absorption. When you think of the current standard of care chemotherapy treatments, they have to be given intravenously. An immediate disadvantage is having to sit in a chair for some time while receiving treatment. The biggest issue now is that chemotherapy can only be provided to the patient as an intravenous infusion over a long period of time. The reason why so many others have failed to make an oral paclitaxel option available is because of a transport protein on the surface of the gastrointestinal (GI) tract, known as P-glycoprotein (P-gp). If any Chemotherapy SOC agent was given now as an oral agent, it would just be pumped right back to the GI tract. This phenomenon occurs because such chemotherapy agents are substrates of P-gp. This is where Athenex comes in. That's because it provides its orascovery platform which uses encequidar, that in turn inhibits P-gp. That's why this biotech is able to take any anti-cancer agent in liquid form and provide it as an oral alternative to a patient. Not only does this improve upon the pharmacokinetic profile of the drug, but it also in turn reduces any safety or tolerability issues associated with it. This point was proven in the recently reported data. For instance:
