3 Promising Breast Cancer Treatments

What is CDK 4/6?

• CDK 4/6 helps control cell creation. They are key regulators of the cycle that helps cells progress from growth to DNA replication. In patients with estrogen receptor positive, or ER+, breast cancer, CDK 4/6 is often over-active.

Slowing activity of CDK 4/6 may help breast cancer patients

Pfizer: Palbociclib

• Targets CDK 4/6 to inhibit its activity• Two Phase 3 studies of palbociclib in advanced/metastatic

breast cancer.– Combined with letrozole versus letrozole plus placebo as a first-line

treatment for post-menopausal patients with ER+, HER2- advanced breast cancer.

– Combined with fulvestrant versus fulvestrant plus placebo in women with hormone receptor-positive, or HR+, HER2- metastatic breast cancer whose disease has progressed after prior endocrine therapy.

Phase 3 tests are underway

Pfizer: Palbociclib

• Significantly delayed disease progression, or PFS, in post-menopausal women with ER+, HER2- locally advanced or metastatic breast cancer when combined with letrozole versus letrozole and placebo.

– Median PFS was 20.2 months versus 10.2 months for letrozole alone.

– Overall survival was 37.5 months versus 33.3 months for letrozole alone.

Phase 2 results were solid

Novartis: LEE011

• Targets CDK 4/6 to inhibit its activity

– A phase Ib/II study of LEE011 in postmenopausal women with HER2- locally recurrent or advanced metastatic breast cancer.

– A phase Ib/II study of LEE011 in patients with advanced ER+ breast cancer.– A phase Ib/II study of LEE011 in postmenopausal women with ER+, HER2- locally

advanced or metastatic breast cancer. – A phase 3 study of LEE011 combined with letrozole for postmenopausal women

with HER2- advanced breast cancer who received no prior therapy for advanced disease.

Source: Clinicaltrials.gov

Phase 1/2 & 3 trials underway

Novartis: LEE011

• Novartis hasn’t publicly detailed human trial data for LEE011 yet, but has given very preliminary preclinical insight of LEE011 efficacy in mice.– Tumor growth was halted in mice treated with LEE011 in each of four

ER+ xenograft models. – Adding letrozole or fulvestrant to LEE011 treatment regimen further

improved results.– Complete tumor regressions were observed for a subset of mice

within each of the triple combination arms and continued for up to four weeks after treatment without significant toxicities.

Pre-clinical results only

Eli Lilly: LY2835210

• Targets CDK 4/6 to inhibit its activity

– A phase 1b Study of LY2835219 in patients with HER2- metastatic breast cancer (currently enrolling patients).

– A phase 2 study of LY2835219 in patients with previously treated HER2- metastatic breast cancer (enrollment begins in May).

– A phase 3 Study of fulvestrant with or without LY2835219, in patients with HER2- locally advanced or metastatic breast cancer (enrollment begins in July).

Source: Clinicaltrials.gov

Phase 1, 2, & 3 trials underway or approaching

Eli Lilly: LY2835210

• Eli Lilly presented phase 1 results during last week’s Association for Cancer Research meeting showing anti-tumor activity for LY2835210 in HR+ metastatic breast cancer patients, a population that makes up 80% of all breast cancer cases.

– 25% of HR+ patients (9 out of 36) treated with LY2835210 responded to the therapy.

– Disease progression was delayed by 9.1 months.

Phase 1 results only

Advancing to the FDA

– Pfizer’s palbociclib has the early edge for getting an FDA yay or nay. Pfizer already has compelling phase 2 data in hand that some analysts hope may allow it to file for a conditional or rolling FDA approval. That may be optimistic. However, investors should keep an eye out to see if Pfizer mentions such a filing in its Q1 earnings conference call.

– Novartis and Lilly are both racing to catch up to Pfizer. Novartis began its phase 3 trial in December and Lilly will begin enrolling patients in July. That means all three will have phase 3 trials underway by fall and investors could learn more about the drug developers timeline for the compounds by year end.

When will these drugs arrive?

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