Diastolic Blood Pressure May Predict Efficacy of Axitinib

TON - February 2010 Vol 3, No 1 — June 2, 2010

Diastolic blood pressure (dBP) ≥90 mm Hg may identify whether a patient will benefit from therapy with axitinib, a selective inhibitor of vascular endothelial growth factor (VEGF) receptors, a new study suggests.

Angel Bair, PhD, AOCNP, from Pfizer Oncology in San Diego, California, presented the results. "Anti-cancer treatments targeting VEGF pathways have demonstrated success in the clinic, but predicting individual patient benefit remains a challenge," said Bair during her presentation. "The use of valid, predictive biomarkers of treatment outcome is important to nurses, particularly if the biomarkers are easily measurable and the procedures are inexpensive."

For this retrospective study, the investigators selected five phase 2 axitinib studies and assessed the association between patient blood pressure and the efficacy of the drug. A total of 230 patients with cytokine- and sorafenib-refractory renal cell carcinoma, ad vanced thyroid cancer, advanced non-small-cell lung cancer, and metastatic melanoma were included in this analysis. All patients were older than 18 years of age and had a baseline blood pressure of ≤140/90 mm Hg.

A twice-daily dose of 5-mg axitinib was given to the patients in 28-day cycles, and blood pressure was measured at each clinic visit.

Retrospectively, the investigators categorized the patients into two groups: those with at least one dBP measurement of ≥90 mm Hg during treatment (n = 130; 67% male) and those who never went above that threshold (n = 100; 63% male). Median age for both groups was 60 years.

The primary outcomes were overall survival, progression-free survival, objective response rate, and adverse events (AEs).

Results from the pooled analysis showed that the ≥90-mm Hg group had significantly longer median overall survival (30.1 months vs 10.2 months, P <.001) and a significantly better objective response rate (43.9% vs 12.0%, P <.001) compared with the <90-mm Hg group, respectively.

Although it wasn't statistically significant, median progression-free survival was also longer for the patients in the ≥90-mm Hg group than for those in the other group (13.1 months vs 5.8 months, respectively; P = .107).

"Basically, we saw a tripling in overall survival and a more than doubling in progression-free survival in the [≥90-mm Hg] group, which were inspiring results," said Bair.

AEs were similar in the two groups, except for fatigue and hand-foot syndrome, which were more frequent for patients in the ≥90-mm Hg group.

"These findings may have clinical implications with respect to drug dosing, treatment monitoring, patient education, and future research," Bair said. "They also can potentially enhance the ability of nurses to recognize [dBP] response as a potential biomarker of treatment effect, leading to better patient compliance."

A new, prospective phase 2 study is currently enrolling patients to further assess the association between blood pressure and efficacy of first-line axitinib therapy, focusing on patients with metastatic renal cell carcinoma.

"If we can show these same benefits in a prospective trial, I think [dBP] response measurement can become a very powerful, very simple tool. It's easy, noninvasive, can be done right at the bedside, and it's almost immediate. It's still early yet in the field, but I think results of the new trial have the potential to significantly impact nursing care of cancer patients receiving axitinib," Bair concluded.

This study was funded by Pfizer Oncology.

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