Lower-Dose Trastuzumab Deruxtecan Shows Favorable Efficacy in HER2-Mutated NSCLC

Trastuzumab deruxtecan at 5.4mg/kg demonstrated clinically meaningful benefit in patients with HER2-mutated non–small cell lung cancer.

Trastuzumab deruxtecan (Enhertu) demonstrated clinically meaningful benefit and a favorable safety profile at the lower of 2 dose levels in patients with HER2-mutated non–small cell lung cancer (NSCLC), according to interim results of the DESTINY-Lung02 trial (NCT04644237) presented at the 2022 European Society for Medical Oncology (ESMO) Congress.1

The blinded, non-comparative phase 2 trial assessed trastuzumab deruxtecan at 5.4 mg/kg and 6.4 mg/kg every 3 weeks, randomly assigning patients 2:1 to receive the lower dose versus the higher dose. The confirmed overall response rate (cORR) in the prespecified early cohort (PEC) of the study was 53.8% (95% CI, 39.5%-67.8%) at the lower dose level and 42.9% (95% CI, 24.5%-62.8%) at the higher dose level. The lower dose also showed superior safety and tolerability, including a lower rate of interstitial lung disease (ILD).

“The safety profile was generally consistent with the established safety profile of trastuzumab deruxtecan, [but] the patients in the 5.4 mg/kg arm experienced a lower frequency of grade 3 or more drug-related AEs [adverse events] and experienced lower drug discontinuation, dose reduction, and drug interruption,” stated Koichi Goto, MD, in his presentation at the 2022 ESMO Congress.

The DESTINY-Lung01 trial (NCT03505710) showed efficacy of this agent at the 6.4 mg/kg dose in patients with previously treated HER2-mutant NSCLC.2 Now the DESTINY-Lung02 trial is investigating the benefit-risk profile of 2 dose levels. The primary end point was cORR by blinded independent central review, while the secondary end points included investigator-assessed cORR, duration of response (DOR), disease control rate (DCR), progression-free survival, overall survival, and safety and tolerability.1

Enrolled patients must have had metastatic NSCLC with a confirmed HER2 mutation. They needed to have undergone prior treatment including platinum-based chemotherapy and were excluded if they had prior or current non-infectious ILD.

At a data cutoff of March 24, 2022, 52 patients in the PEC assigned to receive 5.4 mg/kg of trastuzumab deruxtecan and 28 assigned to 6.4 mg/kg were assessed. This cohort was randomized 4.5 months or earlier before the interim analysis cutoff to provide a better efficacy assessment. In the safety analysis set, 101 were assigned to receive 5.4 mg/kg and 50 were assigned to receive 6.4 mg/kg.

In the 5.4 mg/kg arm of the PEC, there were 27 (51.9%) partial responses (PR), 1 (1.9%) complete response (CR), 19 (36.5%) patients with stable disease (SD), 2 (3.8%) with progressive disease (PD), and 3 (5.8%) who were not estimable (NE). In the 6.4 mg/kg arm, there were 11 (39.3%) PR, 1 (3.6%) CR, 14 (50.0%) SD, 1 (3.6%) PR, and 1 (3.6%) NE.

There were 47 patients (90.4%; 95% CI, 79.0%-96.8%) with a confirmed DCR for the lower-dose arm and 26 (92.9%; 95% CI, 76.5%-99.1%) in the higher-dose arm. The median DOR was NE (4.2 months–NE) and 5.9 months (2.8–NE) for the lower- and higher-dose arms, respectively.

An additional analysis of the response at a data cutoff of June 22, 2022, showed the median DOR was 8.7 months (95% CI, 7.1–NE) and the cORR was 57.7% (95% CI, 43.2%-71.3%) for the 5.4 mg/kg arm.

In terms of safety and tolerability, the rate of any-grade treatment-emergent adverse events (TEAEs) was 92.1% for the patients receiving the lower-dose and 100% for those receiving the higher dose. For grade 3 or higher TEAEs, it was 31.7% versus 58.0%, respectively. Dose reductions associated with TEAEs occurred in 9.9% of the patients in the lower-dose arm, dose discontinuation occurred in 7.9% of this arm, and dose interruption occurred in 13.9%. In the higher-dose arm, the rate of dose reductions due to TEAEs was 26.0%, the rate of dose discontinuations was 16.0%, and the rate of dose interruptions was 30.0%.

ILD, a TEAE of interest, occurred in 5.9% of the lower-dose arm versus 14.0% in the higher-dose arm. In addition, the median duration of treatment was shorter for the higher-dose arm: 4.7 months versus 5.5 months in the PEC and 3.3 months versus 3.7 months in the safety population.

Based on data from this trial, the FDA recently approved the 5.4 mg/kg dose for this patient population.3

“The totality of the evidence and positive benefit-risk balance supported the FDA’s approval of trastuzumab deruxtecan at 5.4 mg/kg, as the first HER2-targeted treatment for patients [with] previously treated HER2-mutated NSCLC and supports the establishment of trastuzumab deruxtecan as their new standard of care in this population,” Goto concluded.1

1. Goto K, Sang-We K, Kubo T, et al. LBA55 - Trastuzumab deruxtecan (T-DXd) in patients (Pts) with HER2-mutant metastatic non-small cell lung cancer (NSCLC): Interim results from the phase 2 DESTINY-Lung02 trial. Ann Oncol. 2022;33(suppl_7):S808-S869. doi:10.1016/annonc/annonc1089
2. Li BT, Smit EF, Goto Y, et al. Trastuzumab deruxtecan in HER2-mutant non-small-cell lung cancer. N Engl J Med. 2022;386(3):241-251. doi:10.1056/NEJMoa2112431
3. FDA grants accelerated approval to fam-trastuzumab deruxtecan-nxki for HER2-mutant non-small cell lung cancer. FDA. August 11, 2022. Accessed September 11, 2022. https://bit.ly/3xbRWTe