Quality-adjusted survival analysis of first-line treatment of hormone-receptor-positive HER2+ metastatic breast cancer with letrozole alone or in combination with lapatinib

AIM

Compare first-line lapatinib plus letrozole (L + Let) versus letrozole monotherapy (Let) in hormone-receptor-positive HER2 + metastatic breast cancer, employing Q-TWiST (quality-adjusted time without symptoms and toxicity) analysis to account for differences in progression times, with offsets for the impact of adverse events during the treatment period.

METHODS

The area under survival curves for each treatment group was partitioned into distinct health states of varying utility: toxicity (TOX), time without toxicity or disease progression (TWiST), and the period following disease progression until death or end of follow-up (REL). The utility-weighted sum of the mean health state durations was derived for each group. The threshold utility analysis evaluates how varying utility values across the states affects Q-TWiST differences between groups, although the method is limited by not varying utilities within each health state.

RESULTS

The primary analysis population was the HER2 + subgroup (n = 219). There was no significant difference between treatments in mean duration of grade 3/4 adverse events prior to progression (L + Let = 1.95 weeks; Let = 2.14 weeks; P = 0.90). Using utility weights of 0.5 for TOX and REL, L + Let was favored for quality-adjusted survival by 8.8 weeks (P = 0.09). The Q-TWiST difference between treatment groups ranged from 8 to 9.5 weeks, favoring combination therapy for all hypothetical utility levels, but none of the comparisons were statistically significant at P = 0.05.

CONCLUSIONS

No significant differences were found between L + Let versus Let in mean duration of severe adverse events. Quality-adjusted survival was favored for the combination treatment arm for all utility levels examined when toxicity was defined by grade 3/4 AEs, but differences between groups were not statistically significant.

Impact of lapatinib plus trastuzumab versus single-agent lapatinib on quality of life of patients with trastuzumab-refractory HER2+ metastatic breast cancer

BACKGROUND

Progression-free survival (PFS) was significantly longer for the lapatinib plus trastuzumab (L+T) arm than for L alone in a phase III, randomized, open-label study of women with human epidermal growth factor receptor 2 positive metastatic breast cancer who had documented progression on at least one T-containing regimen in the metastatic setting. This analysis focused on impact of treatments on health-related quality of life (HRQOL).

METHODS

HRQOL was assessed using the Functional Assessment of Cancer Therapy-Breast (FACT-B) questionnaire. Changes from baseline and time to deterioration were analyzed in the intent-to-treat population.

RESULTS

Differences between the treatment arms in adjusted mean change from baseline favored the L+T arm, ranging from 0.0 to 4.1 (FACT-B), 1.0-4.0 [Functional Assessment of Cancer Therapy-General (FACT-G)], and 0.5-2.7 (Trial Outcome Index). Most differences were not statistically significant, except for FACT-G at week 12 (delta = 4.0, P = 0.037). Similar results were found in a sensitivity analysis that included HRQOL records up to patient withdrawal from original randomized treatment. The longer time to HRQOL deterioration in the L+T arm was not statistically significant (FACT-B hazard ratio, 0.82; 95% confidence interval 0.56-1.20).

CONCLUSION

The addition of lapatinib to trastuzumab prolonged PFS while improving or maintaining near-term HRQOL, suggesting a meaningful clinical benefit to patients.