The San Antonio Breast Cancer Symposium (SABCS) transformed over the past few years into one of the biggest venues for companies releasing data on promising new drug candidates. Breast cancer remains one of the most common forms of cancer globally. Thanks to many new treatment options over the past decade, long-term survival has grown dramatically.
Among the many presentations on the docket at SABCS from Dec. 10 to 14, pivotal trial results stand out for Athenex's (ATNX) oral paclitaxel and Seattle Genetics' (SGEN) tucatinib. Both companies have already heralded their trials as successes; this will be the first public airing of the details.
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Both Athenex and Seattle Genetics plan to submit applications for approval to the U.S. Food and Drug Administration (FDA) during the first quarter of 2020. Their actions and specificity on timing indicate that both companies have a fairly high degree of confidence that they will succeed in securing the approvals.
Athenex reinvents a widely used chemotherapy
Paclitaxel, a backbone chemotherapy drug for decades, holds a storied past. Originally extracted from the bark of the Pacific yew tree by scientists at the National Cancer Institute, its rights passed to Bristol-Myers Squibb (BMY -0.30%), which pushed the drug through clinical development. Once on the market, Taxol, as it was commercially branded, became a blockbuster drug with sales in excess of $1 billion. The book The Story of Taxol: Nature and Politics in the Pursuit of an Anti-Cancer Drug underscores its significance.
Paclitaxel made the World Health Organization's Model List of Essential Medicines as a treatment for breast, lung, and ovarian cancers. Given paclitaxel's widespread use, companies like Athenex have tried to improve its delivery and reduce side effects. The most notable improvement to date is Abraxane, a nanoparticle delivery of paclitaxel, originally developed by Abraxis before Celgene acquired it; Abraxane now resides at Bristol-Myers Squibb, following its buyout of Celgene.
Abraxane cut the infusion time of standard paclitaxel from three hours to 30 minutes. It also eliminated the need to pretreat patients with steroids before the infusion. Those features, plus its ability to shrink tumors, paved the way for FDA approvals in multiple cancers. This week, Tecentriq, an immuno-oncology drug from Roche Holding (RHHBY 1.07%), gained approval as a treatment in first-line non-small cell lung cancer in combination with Abraxane and the chemotherapy drug carboplatin. I suspect that Abraxane'sfuture holds more regulatory approvals as part of a multidrug regimens.
Now back to Athenex: The company's upcoming presentation will highlight the superiority of oral paclitaxel over the intravenous version, based on tumor shrinkage and survival in patients with metastatic breast cancer. Athenex also claims that the oral formulation produced less neuropathy, a side effect of paclitaxel, than the traditional IV version. Investors should focus on the improvement in survival and the side-effect profile.
Elimination of the infusion, whether it's the 30 minutes for Abraxane or three hours for standard paclitaxel, could make a big difference in convenience for patients. An oral option could be viewed positively by patients and their oncologists.
Investors should also be aware that a switch from IV to oral versions creates a change in reimbursement. Currently, the doctor's clinic buys the IV drug, administers the infusion, and then bills the insurance company. With an oral drug, the doctor writes a prescription which the patient then fills at a pharmacy. The patient may be subject to higher out-of-pocket payments, which could deter the use of the oral form. When drugs are too costly, patients often abandon prescriptions at the pharmacy or take fewer pills than prescribed.
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Tucatinib increases survival for late-stage breast cancer patients
Seattle Genetics provided initial data on tucatinib's efficacy in its Oct. 21 press release. In combination with two other anti-cancer drugs, tucatinib proved superior at the primary and secondary endpoints to the two drugs without tucatinib.
Tucatinib reduced the risk of disease progression or death by 46%. The primary endpoint was progression-free survival, the duration of time until a tumor starts growing again. On the secondary endpoint of overall survival, the addition of tucatinib reduced the risk of death by 34%.
Importantly, tucatinib demonstrated a significant benefit for patients whose cancer had spread to their brains, an exceptionally challenging situation to treat. In those with brain metastases, the drug reduced the risk of disease progression or death by 52%.
Safety-wise, patients tolerated tucatinib in combination with the two other cancer drugs. Increased diarrhea and elevated liver enzymes were the most common of the severe side effects but only occurred in a small percentage of patients. Healthcare investors will seek to get a clearer picture of safety at the SABCS presentation.
Investors loved the initial data, causing shares to gain 65% in the past three months. Since the share price is near its all-time highs, the stock could drop if the results underperform investor expectations. However, since data was provided in the October press release, this may be less of an issue.
Investor takeaway
These two oral cancer drugs should provide interesting fodder at SABCS. The novel mechanism of Seattle Genetics' tucatinib provides greater upside potential for biotech investors, especially based on the drug's activity in brain metastases. Meanwhile, oral paclitaxel provides a convenient new option that may be favored by patients and oncologists, but Athenex needs to actively address potential reimbursement roadblocks in order for the drug to gain commercial success.
