Second-line remedy with trastuzumab deruxtecan (T-DXd) led to considerably longer total survival in contrast with trastuzumab emtansine (T-DM1) in sufferers with HER2-positive metastatic breast most cancers, in line with up to date outcomes from the DESTINY-Breast03 part III medical trial introduced on the San Antonio Breast Most cancers Symposium, held December 6-10, 2022.
Virtually all sufferers with HER2-positive metastatic breast most cancers expertise illness development on first-line remedy, requiring transition to a second-line remedy.”
Sara Hurvitz, MD, Professor of Medication on the David Geffen Faculty of Medication on the College of California Los Angeles and Jonsson Complete Most cancers Heart
Two antibody-drug conjugates, T-DXd and T-DM1, are accredited as second-line remedy for this affected person inhabitants. Each therapies make the most of trastuzumab to hunt HER2-expressing cells and ship a cytotoxic drug. Within the case of T-DXd, the cytotoxic payload induces cell demise by inhibiting topoisomerase; the conjugated drug of T-DM1 kills cells by disrupting microtubule meeting.
The DESTINY-Breast03 trial in contrast the efficacy and security of T-DXd with these of T-DM1 in sufferers with HER2-positive metastatic breast most cancers that progressed on or after first-line remedy. Beforehand printed interim outcomes from the trial demonstrated that sufferers handled with T-DXd had considerably longer progression-free survival (PFS) in contrast with sufferers who acquired T-DM1. These outcomes led to the approval of T-DXd as a second-line remedy for this affected person inhabitants. Nevertheless, total survival knowledge had not been reached within the first interim evaluation.
“Whereas PFS advantages are essential, the gold customary measure of efficacy is total survival,” mentioned Hurvitz.
In her presentation, Hurvitz will share beforehand unreported total survival knowledge from the trial, in addition to up to date PFS and security knowledge. Among the many 524 sufferers enrolled within the trial, 261 acquired T-DXd, and 263 acquired T-DM1. The median examine follow-up was 28.4 months for the T-DXd arm and 26.5 months for the T-DM1 arm.
New knowledge confirmed that sufferers handled with T-DXd had a 36 p.c decrease threat of demise than these handled with T-DM1, a statistically important enchancment. As well as, total survival charges had been considerably larger for sufferers handled with T-DXd: After 12 months, 94.1 p.c of sufferers within the T-DXd arm had been alive, in contrast with 86 p.c of these within the T-DM1 arm. After 24 months, total survival charges had been 77.4 p.c and 69.9 p.c for sufferers handled with T-DXd and T-DM1, respectively.
Up to date PFS knowledge continued to favor T-DXd, and Hurvitz will report median values for the primary time. The median PFS in sufferers handled with T-DXd was 28.8 months, in contrast with 6.8 months for sufferers handled with T-DM1. Goal responses had been noticed in 78.5 p.c of sufferers who acquired T-DXd and 35 p.c of sufferers handled with T-DM1. Moreover, 21.1 p.c of sufferers handled with T-DXd had an entire response, as in contrast with 9.5 p.c of sufferers handled with T-DM1.
Grade 3 or larger treatment-related adversarial occasions had been noticed in 56.4 p.c and 51.7 p.c of sufferers within the T-DXd and T-DM1 arms, respectively. Drug-related interstitial lung illness/pneumonitis was noticed in 15.2 p.c and three.1 p.c of sufferers within the T-DXd and T-DM1 arms, respectively. Hurvitz famous that new circumstances of interstitial lung illness/pneumonitis had been gentle or reasonable in severity.
“The outcomes of this evaluation demonstrated exceptional total survival and continued PFS profit with T-DXd in sufferers with HER2-positive metastatic breast most cancers who progressed on prior remedy, additional supporting the usage of T-DXd over T-DM1 within the second-line setting,” mentioned Hurvitz. “With this total survival evaluation, we will verify that the beforehand demonstrated profit from T-DXd in PFS enchancment transforms right into a statistically important enchancment in total survival, a considerable benefit for our sufferers.
“As well as, T-DXd continued to reveal a manageable and tolerable security profile, with related charges of treatment-related adversarial occasions between remedy arms,” she added.
Future analyses of DESTINY-Breast03 could examine the efficacy of T-DXd in sufferers with mind metastases and discover predictive markers of response, Hurvitz famous. Ongoing research goal to find out the efficacy and security of T-DXd as a first-line remedy for sufferers with HER2-positive metastatic breast most cancers.
A limitation of the examine was the disproportionate enrollment of Asian sufferers as in contrast with North American and European sufferers. A further limitation was that median total survival was not reached on the time of this evaluation.
The examine was supported by Daiichi Sankyo and AstraZeneca. Hurvitz is married to a shareholder/stockholder in Ultimate Implant; has acquired honoraria from Daiichi Sankyo; and has acquired funding to her establishment from Ambrx, Amgen, AstraZeneca, Arvinas, Bayer, Daiichi Sankyo, CytomX Therapeutics, Dantari, Dignitana, G1 Therapeutics, Genentech/Roche, Gilead Sciences, GSK, Immunomedics, Eli Lilly and Firm, MacroGenics, Novartis, Pfizer, OBI Pharma, Phoenix Molecular Designs, Orinoco Prescribed drugs, Pieris Prescribed drugs, Puma Biotechnology, Radius Well being, Samumed, Sanofi, Seattle Genetics, and Zymeworks.