- The Eli Lilly drug Verzenio significantly reduced the risk of breast cancer returning or death in a Phase 3 trial of more than 5,600 patients at high risk of relapse following surgery, the drugmaker said in a Tuesday statement.
- Lilly didn't disclose critical details about the magnitude of the drug's benefit. But it did say the drug, when given alongside endocrine therapy in women with certain types of tumors, kept breast cancer at bay longer than standard treatment. Lilly plans to ask regulators to expand Verzenio's approval to include the new data.
- The results come two weeks after a rival Pfizer drug, Ibrance, failed in a similar trial, albeit in a different study population. Lilly's data mark the first time that one of a new class of breast cancer drugs known as CDK 4/6 inhibitors showed a benefit in this setting.
Ever since Pfizer's Ibrance won its first approval as a breast cancer treatment in 2015, it has led the way for CDK 4/6 inhibitors, which block enzymes tumors rely on to grow and multiply. In the process, Ibrance has become Pfizer's top-selling cancer drug, with $5 billion in sales in 2019.
Lilly and Novartis won approvals of similar drugs, respectively Verzenio and Kisqali, in 2017, and both companies have been attempting to make inroads on Ibrance's dominant position. They haven't come close yet, with Ibrance maintaining a 80%-plus market share for the treatment class.
Key to all three drugmakers' strategy is proving that CDK4/6 inhibitors can benefit patients earlier in the course of their breast cancer treatment. All three drugs are approved for advanced breast cancer patients whose tumors have already metastasized. But Pfizer, Lilly and Novartis each have studies underway testing their drugs as "adjuvant" treatments, alongside standard endocrine therapy like letrozole.
Each study has slight differences in study populations. Pfizer, for instance, enrolled patients in the Phase 3 PALLAS study based on their cancer stage, either Stage 2 or Stage 3. In the MONARCHe study reported Tuesday, Lilly only enrolled patients with Stage 3 cancer and used disease markers to define which were at high risk of recurrence.
The goal, for each, is the same, however: Show their drugs can keep cancers from returning, when they spread and become more deadly. To do so, the companies are using a measure known as invasive disease-free survival, which some criticize as a weaker standard than the stricter test of overall survival.
Proving the benefits of wider use could be lucrative. Pfizer has said that an approval in the adjuvant setting could double the patients eligible for Ibrance treatment. About 30% of breast cancer patients with tumors that are hormone receptor positive, but negative for a protein called HER2 are at risk of their cancers returning.
In late May, however, Pfizer said its Phase 3 PALLAS study failed to show a benefit to Ibrance in pre- and post-menopausal women or men with Stage 2 or Stage 3 HR-positive, HER2-negative breast cancer. Another trial, dubbed PENELOPE-B, is also testing adjuvant use of Ibrance and should produce results later this year.
The PALLAS setback had dimmed expectations for CDK 4/6 inhibitors in early treatment settings, making Lilly's success with MONARCHe somewhat of a surprise. MONARCHe also studied Verzenio in HR-positive, HER2-negative breast cancer.
Lilly didn't provide any details, only noting that the benefit it observed is significant and that side effects were consistent with prior tests. It's still unclear how much longer the drug helps cancer patients survive than they would otherwise.
Details from the study will be presented at a medical meeting later this year, said Lilly, which also plans to submit the results to regulators by the end of the year.
Competition could still emerge. Novartis is running a Phase 3 trial in early breast cancer, with results expected in 2022, and Ibrance could show a good outcome in PENELOPE-B.
Investors, though, seem encouraged by Lilly's newfound advantage. Shares in the Indianapolis drugmaker climbed more than 13% in early trading Tuesday, adding roughly $15 billion to the drugmaker's market value.
"This is a clear win for Lilly," wrote Cantor Fitzgerald analyst Louise Chen in a note to clients. "We wonder if physicians will use Verzenio off label in the adjuvant setting given the positive data today."