Carboplatin May Be Omitted in HER2-Positive Breast Cancer Treatment

Some patients with HER2-positive breast cancer may be able to safely skip carboplatin chemotherapy, particularly those with lower-risk disease, according to recent trial data. The findings, presented at the 43rd Annual Miami Breast Cancer Conference, offer a potential path to reduce treatment toxicity without compromising effectiveness.

Current Standard of Care

Currently, a regimen combining carboplatin, a taxane, trastuzumab, and pertuzumab (TCbHP) is a preferred treatment option, as outlined by the National Comprehensive Cancer Network (NCCN), for patients with stage II–III HER2-positive breast cancer. However, carboplatin can cause significant side effects.

neoCARHP Trial Results

The phase 3 neoCARHP trial (NCT04858529) investigated whether omitting carboplatin would impact treatment outcomes. Results showed a pathologic complete response (pCR) rate of 64.1% in the group that did not receive carboplatin (THP regimen) – a rate comparable to the 65.9% pCR rate observed in patients treated with the full TCbHP regimen. (95% CI, 59.1–69.0% for THP and 60.9–70.6% for TCbHP).

Reduced Toxicity with Carboplatin Omission

Importantly, omitting carboplatin in the THP group led to significantly fewer severe side effects. Grade 3 or 4 adverse events occurred in 20.7% of patients on the THP regimen, compared to 34.6% of those treated with TCbHP. Serious adverse events were also less frequent with THP.

Study Limitations and Future Research

Researchers noted two limitations of the neoCARHP trial. First, the study was primarily conducted with patients of Chinese descent, which may limit the generalizability of the findings to other populations. Second, long-term outcomes, including event-free survival (EFS), disease-free survival, and overall survival (OS), are still being monitored. Further research with more diverse patient populations and extended follow-up will be crucial to confirm whether the non-inferiority in pCR translates to equivalent survival rates.

Biomarker Analysis and Lower-Risk Disease

A separate analysis, the EA1181 study (CompassHER2 pCR), focused on patients receiving the THP regimen. This study identified that lower estrogen receptor (ER) expression and higher HER2 expression (immunohistochemistry [IHC] 3+) were strong predictors of pCR. High HER2DX scores may help identify patients who could benefit from dual HER2 blockade alone or a less intensive chemotherapy regimen, potentially minimizing toxicity.

Implications for Precision Medicine

These findings underscore the growing advancements in precision medicine for breast cancer. By carefully assessing individual patient characteristics and risk factors, clinicians can tailor treatment plans to maximize benefits while minimizing unnecessary toxicities. The ability to potentially omit carboplatin in select patients represents a significant step towards more personalized and effective breast cancer care.

Source: onclive.com, Cure Magazine, clinicaltrials.gov, clin.larvol.com