Pfizer's oral kinase inhibitor Tukysa has shown a significant reduction in the risk of death or disease progression for patients with HER2-positive metastatic breast cancer when used as a first-line treatment, according to results from the Phase III HER2CLIMB-05 study.
Analysts at BMO Capital Markets commented on the findings, stating that Tukysa’s performance positions it to “become a new standard regimen” for this patient population. “Results today are a positive advancement. . .demonstrating more upside from expansion in oncology in the near term,” they said.
Despite these positive outcomes, BMO highlighted concerns about liver toxicities observed during the trial. The analysts noted that there was a “meaningfully higher” incidence of liver toxicity among patients treated with Tukysa, which may influence physicians’ prescribing decisions. However, they also stated, “We expect most physicians to be comfortable with this risk trade-off, as efficacy outcomes appear to more than make up for any safety concerns.”
The HER2CLIMB-05 trial involved over 320 patients who had previously undergone induction treatment with Herceptin, Perjeta and taxane without showing disease progression. Participants were assigned either a combination of Tukysa with Roche’s Herceptin and Perjeta or just Herceptin and Perjeta as a control.
Data presented at the 48th San Antonio Breast Cancer Symposium indicated that adding Tukysa reduced the risk of disease progression or death by 35.9% compared to controls. Median progression-free survival was 24.9 months in the Tukysa group versus 16.3 months in the control group. Overall survival data was still immature but favored Tukysa numerically.
Pfizer reported that the benefit in progression-free survival remained consistent across various patient subgroups, regardless of whether their diagnosis was recurrent or de novo, whether brain metastases were present, and whether their disease was hormone receptor-positive or negative.
“Improvements in PFS of this magnitude are clearly significant and clinically meaningful,” BMO added in its note, “potentially opening the opportunity for [Tukysa] to be added as a standard 1L treatment option.”
Safety data showed higher rates of grade 3 or above elevations in liver transaminases among those receiving Tukysa; Pfizer described these side effects as “typically manageable and reversible” with dose adjustments. More detailed information published in the Journal of Clinical Oncology revealed that 13.5% of participants discontinued due to adverse events related to treatment.
