High Response Rates With T-DXd in Early HER2-Low Breast Cancer

SAN Antonio – How do you shoot at an invisible goal? It appears counterintuitive, however trastuzumab deruxtecan (T-DXd) (Enhertu), which mixes an antibody focused to HER2 with a poisonous payload, confirmed promising preliminary exercise in opposition to localized hormone receptor–optimistic breast cancers with solely low ranges of HER2 expression (HR+/HER2-low).

Dr Aditya Bardia

n the investigator-initiated TRIO-US B-12 TALENT examine neoadjuvant T-DXd both alone or together with the hormone remedy anastrazole, the target response fee (ORR) with T-DXd alone was 68%, in contrast with 58% for T-DXd plus anastrazole, reported Aditya Bardia, MD, MPH, a medical oncologist with Massachusetts Normal Hospital Most cancers Middle in Boston. He lately offered the examine findings on the 2022 San Antonio Breast Most cancers Symposium.

“The examine offers a wealthy platform for added translational analysis to guage extra delicate strategies of HER2 detection, develop predictive biomarkers, and perceive mechanisms of resistance in residual illness which might information subsequent therapeutic methods, together with mixture remedy,” he mentioned in an oral summary session on the assembly.

Not-So-Harmless Bystander

In an interview, Bardia defined that the T-DXd could have efficacy in HER2-low cancers due to a bystander impact.

“With these antibody drug conjugates, in case you have the antigen, the ADC binds to the antigen, will get internalized, and releases the payload, however the payload has a bystander impact … it is membrane permeable, so it will probably go outdoors and have an effect on different cells that don’t specific the antigen. So for HER2-low tumors, even when there may be HER2 heterogeneity or if there are some cells that don’t specific HER2, this may work due to the bystander impact,” he mentioned.

Though neoadjuvant chemotherapy with an anthracycline and taxane is commonly used to deal with sufferers with high-risk localized HR-positive breast most cancers, the remedy is related to low pathologic full response (pCR) charges, radiological response charges of round 50%, and important toxicities, together with myelosuppression, neuropathy, cardiomyopathy, and leukemia danger, Bardia mentioned.

At Cross Functions

The trial included each a T-DXd monotherapy arm and a second arm containing the antibody drug conjugate (ADC) with endocrine remedy. The rationale for the latter is that there’s documented “cross-talk” between the estrogen receptor (ER) and HER2.

“In tumors that turn into endocrine resistant, you see a rise within the HER2 pathway, and in the event you block ER, you see that HER2 goes up and vice versa. Should you simply block HER2 alone, the expression of ER can go up, and in the event you block the PI3 kinase alone, the expression of ER goes up,” he mentioned.

Twin blockade will be efficient with antibody-based remedy or with tyrosine kinase inhibitors, however with an ADC, the twin blockade technique could also be much less efficient, Bardia mentioned, “as a result of in case you have an ADC, you want HER2, the ADC binds to HER2, then offers the payload to the most cancers cells and primarily kills the most cancers cells,” Bardia defined in a media briefing held previous to his presentation.

In reality, the T-DXd–anastrozole mixture was related to a decrease total response fee within the examine than T-DXd alone, however Bardia cautioned about overinterpreting these outcomes, because the examine included solely 39 sufferers.

Research Particulars

The investigators enrolled 58 sufferers – 56 pre- and postmenopausal girls and a couple of males – with HR+/HER2-low tumors decided by native and/or central overview, and operable stage II or III cancers.

After stratification by HER2 expression stage and menopausal standing, the sufferers had been randomized to obtain both T-DXd alone at a dose of 5.4 mg/kg, or with T-DXd on the identical dose plus anastrozole, with males and premenopausal girls additionally receiving a gonadotropin-releasing hormone analog.

The protocol initially referred to as for six cycles of remedy, however was amended in February 2022 to extend the quantity to eight for newly enrolled individuals and sufferers who had been already on examine therapy however had not but had surgical procedure.

Nearly all of sufferers in every arm had invasive ductal cancers, and most had HER2 expression on immunohistochemistry (IHC) of 1+, which is mostly thought of to be HER2-negative. Nonetheless, there was solely modest concordance between native and central overview in figuring out HER2 expression ranges, Bardia famous. Certainly, the whole query of HER2-low cancers, whether or not they compose a separate scientific entity from different cancers and standardize testing, was the topic of a particular session at this yr’s SABCS.


Total response fee, the first endpoint, was 68% within the T-DXd arm and 58% within the T-DXd plus anastrazole arm.

Though the low response fee with the mixture means that endocrine remedy might not be useful on this affected person inhabitants, it is nonetheless too early to say so conclusively, Bardia mentioned.

Wanting on the change in HER2 expression by IHC from baseline to surgical procedure, they discovered that 48.6% of sufferers had a change in HER2 IHC expression after T-DXd therapy, and that just about 90% of those sufferers had a lower in expression ranges.

Amongst 42 sufferers with accessible information on residual most cancers burden (RCB) on the time of knowledge cutoff, one affected person within the T-DXd alone arm with stage 3A illness had an RCB of 0, equal to a pathologic full response (pCR). There have been no different RCB 0 tumors after surgical procedure in both examine arm. The speed of mixed RCB and RCB 1 (close to pCR) was about 15% in every arm.

In all, 3 of the 58 sufferers within the examine (5.2%) required dose reductions due to opposed occasions. There have been no circumstances of grade 3 or larger pneumonitis, and no circumstances of both cardiomyopathy or neuropathy.

Manner Higher Than Chemotherapy?

“It was very thrilling once we received the DESTINY-Breast04 outcomes exhibiting this spectacular exercise of trastuzumab deruxtecan on this HER2-low entity, and now we all know that hormone-positive [tumors], the vast majority of them are HER2-low. It was actually encouraging, it was apply altering, however we had been left questioning about this HER2-low entity, and might we act on it within the earlier setting,” commented Jason A. Mouabbi, MD, from the College of Texas MD Anderson Most cancers Middle in Houston.

“The great thing about the TRIO-US B-12 TALENT examine is that it seemed on the neoadjuvant setting the place we all know these sufferers who’re hormone-positive often don’t reply effectively to chemotherapy,” he mentioned in an interview.

He mentioned that though the examine did not examine T-DXd to chemotherapy, “it is a superb first begin.”

An total response fee close to 70% “is one thing wonderful. I am actually excited to see it in opposition to chemo. I feel it should do approach higher,” Mouabbi mentioned.

The examine was performed by the Translational Analysis In Oncology (TRIO)-US community. Funding was supplied by Daiichi Sankyo, the maker of trastuzumab deruxtecan (Enhertu). Bardia serves as a advisor or advisory board member for Pfizer, Novartis, Genentech, Merck, Radius Well being, Immunomedics/Gilead Sciences, Sanofi, Daiichi Sankyo, AstraZeneca, and Eli Lilly, and has acquired analysis funding from Genentech, Novartis, Pfizer, Merck, Sanofi, Radius Well being, Immunomedics/Gilead Sciences, Daiichi Sankyo, AstraZeneca, and Eli Lilly.

Mouabbi disclosed honoraria from BostonGene, Cardinal Well being, Napo Prescribed drugs, and Fresenius Kabi.

This text initially appeared on MDedge.com, a part of the Medscape Skilled Community.

Categorized as News

Leave a comment

Your email address will not be published. Required fields are marked *