March 2020: Predefined surgical analysis of the randomized BrighTNess trial

BrighTNess (GBG 81, NCT 02032277) was a multicenter, double-blind, placebo-controlled, randomized phase III trial comparing paclitaxel plus carboplatin plus Poly(ADP-ribose) polymerase (PARP) inhibitor veliparib with paclitaxel plus carboplatin and with paclitaxel alone, each followed by standard neoadjuvant chemotherapy with doxorubicin/cyclophosphamide (AC) in triple-negative breast cancer (TNBC) patients. Women with operable, clinical stages II to III TNBC who underwent germline BRCA (gBRCA) mutation testing before initiating neoadjuvant systemic therapy (NST) were eligible to participate. Primary endpoint analysis demonstrated that overall, an addition of veliparib to NST did not increase the pCR rate in the breast and lymph nodes in TNBC patients. In contrast, the addition of veliparib plus carboplatin or carboplatin alone to paclitaxel followed by AC resulted in a significant improvement in pCR rates compared to paclitaxel alone. The increased toxicity of carboplatin with or without veliparib did not impact the delivery of neoadjuvant chemotherapy (Loibl et al. Lancet Oncol. 2018). Predefined secondary endpoint analysis included the rate of conversion from breast-conserving therapy (BCT) ineligible to BCT eligible and association of response to NST, gBRCA status, and region of treatment with surgical choice.

This study reported the results of the secondary endpoints. Among the 634 randomized patients (median age, 51 [range 22-78] years), pre- and post-NST assessments were available for 604 patients. Overall, 346 patients (57.3%) underwent BCT, and 258 (42.7%) underwent mastectomy. Of 458 (76.5%) patients considered BCT eligible at baseline, 425 (92.8%) remained eligible after NST, of whom 300 (70.6%) underwent BCT. Of 141 (23.5%) patients deemed BCT ineligible at baseline, 75 (53.2%) converted to BCT eligible after treatment, of whom 42 (56.0%) underwent BCT. Hence, NST administration increased the absolute number of BCT-eligible patients from 458 (76.5%) to 502 (83.8%), of whom 342 (68.1%) underwent BCT. Patients treated in Europe and Asia were more likely to undergo BCT (odds ratio 2.66 [95%CI 1.84-3.84]) compared with those treated in North America. Among patients without gBRCA mutation undergoing mastectomy, those treated in North America were more likely to undergo contralateral prophylactic mastectomy (70.4% [57 of 81] vs 20.0% [6 of 30]; p<0.001). Rates of pCR were similar between patients deemed BCT eligible at baseline and those who were BCT ineligible but converted to BCT eligibility after NST (55.3% [235 of 425] vs 49.3%[37 of 75]; p=0.38).

In conclusion, surgical results of the BrighTNess trial demonstrate that neoadjuvant chemotherapy makes BCT possible in half of patients with stages II to III TNBC who would have otherwise required mastectomy. Therefore, the overall percentage of those patients eligible for BCT increases from 76.5% at diagnosis to 83.8% after NST. However, the lower BCT rates among eligible patients and higher bilateral mastectomy rates among patients without gBRCA mutation in North America need further investigation.

Golshan M, Loibl S, Wong SM, Houber JB, O'Shaughnessy J, Rugo HS, Wolmark N, McKee MD, Maag D, Sullivan DM, Metzger-Filho O, Von Minckwitz G, Geyer CE Jr, Sikov WM, Untch M. Breast Conservation After Neoadjuvant Chemotherapy for Triple-Negative Breast Cancer: Surgical Results From the BrighTNess Randomized Clinical Trial. JAMA Surg. 2020; doi:10.1001/jamasurg.2019.5410.

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