ASCO 2025: THP Without Carboplatin Shows Noninferior pCR Rates, Improved Tolerability in HER2+ Early Breast Cancer

Key Takeaways

THP showed noninferior pCR rates and improved tolerability compared to TCbHP in HER2-positive early breast cancer patients.
The trial involved 774 patients, with THP demonstrating fewer grade 3 and 4 adverse events than TCbHP.
Omitting carboplatin from the regimen may offer an effective de-escalated neoadjuvant strategy for this patient population.
The ongoing adjuvant phase will further evaluate long-term outcomes, including survival and safety metrics.

About 64.1% of patients receiving taxane, trastuzumab, and pertuzumab (THP) without carboplatin had pathological complete response rates (pCRs).

In the phase 3 neoCARHP clinical trial (NCT04858529), taxane, trastuzumab, and pertuzumab (THP) provided noninferior pathological complete response rates (pCRs) and improved tolerability in patients with human epidermal growth factor receptor 2 (HER2)-positive early breast cancer compared with taxane, carboplatin, and trastuzumab plus pertuzumab (TCbHP). These findings, which were presented at the 2025 American Society of Clinical Oncology in Chicago, Illinois, suggest that omitting carboplatin from treatment regimens could be an efficacious de-escalated neoadjuvant strategy in this patient population.^1,2

Image credit: Chutima | stock.adobe.com

HER2+ breast cancer is a fast-growing disease that can spread from the breast to other areas of the patient’s body. This specific type shows high levels of the HER2 protein, which manages how cells grow and divide. In 2023, invasive breast cancer was predicted to affect more than 290,000 women, and of these cases, approximately 15% to 20% are projected to be HER2+ breast cancer. If caught early, the cancer can often be treated and cured, according to Cleveland Clinic.³

neoCARHP was a multicenter, open-label, randomized, noninferiority phase 3 trial (NCT04858529) that compared the efficacy and safety of TCbHP with THP in the neoadjuvant setting. Conducted across 15 hospitals, 774 patients aged 18 years or older with untreated, stage II to III, invasive HER2+ breast cancer were enrolled between April 30, 2021, and August 27, 2024. Additionally, patients were stratified by nodal and hormone receptor status and randomly assigned to receive six 3-week cycles of an investigator-selected taxane (docetaxel, paclitaxel, or nab-paclitaxel) plus trastuzumab (8 mg/kg loading dose, then 6 mg/kg every 3 weeks) and pertuzumab (840 mg loading dose, then 420 mg every 3 weeks), with carboplatin (AUC 6 mg/mL per min; n = 387), or this regimen without carboplatin (n = 387).^1,2

The study’s primary end point was the pCR rate in the breast and axilla (ypT0/is ypN0), which was assessed in the modified intent-to-treat (mITT) population (all randomly assigned patients who received at least 1 dose of study medication). In addition, the primary efficacy analysis was performed using the Cochran-Mantel-Haenszel χ²test (stratified by nodal and hormone receptor status), with a prespecified noninferiority margin of -10%. Secondary end points include clinical response, event-free survival, disease-free survival, overall survival, safety, and number of patients who underwent breast-conserving surgery. Of note, the adjuvant phase of the trial is currently ongoing.^1,2

About the Trial

Trial Name: Neoadjuvant TCHP Versus THP in Patients With HER2-positive Breast Cancer (neoCARHP Study)

ClinicalTrials.gov ID: NCT04858529

Sponsor: Guangdong Provincial People's Hospital

Completion Date (Estimated): April 30, 2025

A total of 766 patients were included in the mITT population (THP: n = 382; TCbHP: n = 384). The findings demonstrated that approximately 64.1% (n = 245 [95% CI 59.2—68.8]) of patients in the THP group achieved pCR, compared with 65.9% (n = 253 [95% CI, 61.0—70.5]) of patients in the TCbHP group (absolute difference -1.8%; 95% CI, -8.5—5.0; odds ratio 0.93; 95% CI, 0.69—1.25; P = .0089).¹

Regarding safety, patients who received THP were observed to have fewer grade 3 and 4 adverse events (AEs; n = 79, 20.7%) and serious AEs (n = 5, 1.3%) compared with those receiving TCbHP (grades 3-4: n = 133, 34.6%; serious AEs: n = 18, 4.7%). The most common grades 3 or 4 AEs were neutropenia (THP: n = 26, 6.8%; TCbHP: n = 63, 16.4%), leukopenia (THP: n = 21, 5.5%; TCbHP: n = 57, 14.8%), and diarrhea (THP: n = 10, 2.6%; TCbHP: n = 16, 4.2%). Notably, there were no treatment-associated deaths observed or reported.¹

Overall, the investigators noted that excluding carboplatin in the THP treatment regimen may be a beneficial treatment for patients with HER2+ early breast cancer. The investigators also note their optimism that THP can be efficacious when de-escalated in the neoadjuvant setting.¹

REFERENCES

1. Gao HF, Li W, Wu Z, et al. LBA500 — De-escalated neoadjuvant taxane plus trastuzumab and pertuzumab with or without carboplatin in HER2-positive early breast cancer (neoCARHP): A multicentre, open-label, randomised, phase 3 trial. J Clin Oncol. 43, 2025 (suppl 17; abstr LBA500). doi:10.1200/JCO.2025.43.17_suppl.LBA500

2. Neoadjuvant TCHP Versus THP in Patients With HER2-positive Breast Cancer (neoCARHP Study). ClinicalTrials.gov: NCT04858529. Updated November 7, 2023. Accessed June 6, 2025. https://clinicaltrials.gov/study/NCT04858529

3. Cleveland Clinic. HER2-Positive Breast Cancer. Accessed June 6, 2025. https://my.clevelandclinic.org/health/diseases/25213-her2-positive-breast-cancer

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