Efficacy of a novel interstitial lung disease monitoring program in breast cancer patients undergoing treatment with trastuzumab-deruxtecan.

PURPOSE

Interstitial lung disease (ILD) is a well described and potentially fatal complication of trastuzumab-deruxtecan (T-DXd). It is currently unknown if specific monitoring is beneficial in the early detection of ILD in these patients. We describe the efficacy and feasibility of a novel ILD monitoring protocol in breast cancer patients treated with T-DXd at our institution.

METHODS

An ILD monitoring protocol developed at our institution included baseline and ongoing monitoring with pulmonary function testing (PFTs) and high-resolution chest computed tomography (HRCT) at pre-specified intervals. Patients with metastatic HER2+ or HER2-low breast cancer treated at Huntsman Cancer Institute who received ≥ 1 cycle of T-DXd between 2020 and 2023 were included (n = 68). Patient outcomes and provider adherence to the protocol were retrospectively evaluated. Providers were classified as "no adherence" if they did not elect to participate in any elements of the recommended protocol or as "some adherence" if they had at least some monitoring per protocol.

RESULTS

10 cases of ILD were identified with an incidence of 12% (3/25) in the no adherence group and 16% (7/43) in the some adherence group. ILD cases in the no adherence group included one grade 2 and two grade 5 cases. The some adherence group included three grade 1 and four grade 2 cases.

CONCLUSION

An ILD monitoring protocol consisting of baseline PFTs and ongoing monitoring with PFTs and HRCT is a feasible approach as evidenced by a majority provider adherence rate. This type of protocol may be effective in preventing severe cases of ILD and identifying grade 1 events that may permit treatment re-challenge.