Cancer drug development is increasingly targeted at very specific patient subpopulations, with a focus on targeting specific tumor gene mutations and molecular pathways, according to a presenter at the Academy of Managed Care Pharmacy (AMCP) 2017 Nexus.
Antineoplastic agents represent a growing proportion of specialty drug spending, said Edward Li, PharmD, MPH, BCOP, a professor at the University of New England College of Pharmacy in Portland, Maine, during his October 17 session.
Li reviewed the evidence base for three key cancer therapies likely to be FDA approved in the coming year that could change treatment guidelines and improve outcomes, and the overall implications for cancer expenditures.
“Expenditures for oral oncolytics increased to $6 billion in 2012 from 1 billion in 2003,” Li said. “The percent dispensed through specialty pharmacy increased to 61% from 26%.”
Potential 2018 approvals include three key oral agents, Li reported:
· The CDK4/6 inhibitor verzenio (abemaciclib, Eli Lilly)
· The second-generation Bruton’s tyrosine kinase (BTK) inhibitor acalabrutinib (Acerta)
· The tropomyosin kinase receptor inhibitor larotrectinib (Loxo Oncology).
“Since all three agents are designated as breakthrough therapies, the data demonstrating their clinical utility is not yet mature,” he cautioned. “The overall potential impact of these agents on overall oncology drug spending is expected to be low to moderate.”
Abemaciclib is more selective for CDK4 than CDK6 or 9, with absorption across the blood-brain barrier, Li noted. It can be dosed continuously as a monotherapy or with fulvestrant hormone therapy despite higher rates of diarrhea. It involves less bone-marrow suppression than other CDK inhibitors. Approved by the FDA in September 2017 for use with fulvestrant for patients with endocrine-therapy-refractory disease, abemaciclib was developed for hormone receptor-positive, HER2-negative advanced breast cancer for postmenopausal patients with prior endocrine therapy.
“We have had two seminal studies,” Li said. The studies enrolled women in “ultra-last-stage settings” with endocrine-therapy-refractory disease, he said.
Overall survival data is not yet available but abemaciclib is associated with prolonged progression-free survival, Li said.
Abemaciclib with fulvestrant will compete with palbociclib as a second-line therapy after endocrine treatment fails, Li said.
Abemaciclib will serve a niche population of patients with cancer: those with tumors refractory to prior endocrine therapy and one or two chemotherapies, including a taxane, and who have had no prior exposure to CDK4/6 inhibitors, Li said.
Abemaciclib will have a moderate impact on biologics spending, Li predicted. “We will see low-moderate use as a single agent, depending on how many patients are CDK4/6 naïve,” he said. “It will replace palbociclib to some degree.”