Real-world use patterns, effectiveness, and tolerability of sacituzumab govitecan for second-line and later-line treatment of metastatic triple-negative breast cancer in the United States.

PURPOSE: Patients with metastatic triple-negative breast cancer (mTNBC) have poor prognosis and limited treatment options. Sacituzumab govitecan (SG), a Trop-2-directed antibody-drug conjugate, is approved for patients with mTNBC who have received ≥ 2 systemic therapies (≥ 1 in the metastatic setting) based on the ASCENT study (NCT02574455). The current study describes real-world SG use and outcomes in patients with mTNBC in the United States. METHODS: This retrospective, observational study included adult patients with mTNBC from the ConcertAI Patient360™ database who received SG in the second line (2L) and later from April 2020 to May 2022. SG use patterns, effectiveness, and tolerability are described. RESULTS: This analysis included 230 patients (median age 60 years, 26% Black, 17% with ECOG performance status ≥ 2, 66% in community settings; median of 2 prior lines of treatment in the metastatic setting); median follow-up was 7.2 months. Median (95% CI) real-world overall survival was 10.0 (8.3-11.1) months for all patients and 13.9 (9.8-not estimable) months in the 2L subgroup (n = 77). Granulocyte-colony stimulating factor (G-CSF) was administered concomitantly with SG in 134 (58%) patients; 35 (15%) received G-CSF for the first time. Median (IQR) time from SG start to G-CSF use was 8.5 (8.0-29.0) days. Seventeen (7%) patients discontinued SG due to toxicity. CONCLUSIONS: Using a real-world, ethnically diverse population of patients with mTNBC presenting with poor prognosis, these data reinforced the findings from ASCENT. In routine clinical practice, SG is an effective treatment in the 2L setting, consistent with treatment guidelines.

Searching for the "Holy Grail" of breast cancer recurrence risk: a narrative review of the hunt for a better biomarker and the promise of circulating tumor DNA (ctDNA).

BACKGROUND: This paper is a narrative review of a major clinical challenge at the heart of breast cancer care: determining which patients are at risk of recurrence, which require systemic therapy, and which remain at risk in the survivorship phase of care despite initial therapy. METHODS: We review the literature on prognostic and predictive biomarkers in breast cancer with a focus on detection of minimal residual disease. RESULTS: While we have many tools to estimate and refine risk that are used to individualize local and systemic therapy, we know that we continue to over treat many patients and undertreat others. Many patients also experience what is, at least in hindsight, needless fear of recurrence. In this review, we frame this dilemma for the practicing breast oncologist and discuss the search for what we term the "holy grail" of breast cancer evaluation: the ideal biomarker of residual distant disease. We review the history of attempts to address this problem and the up-to-date science on biomarkers, circulating tumor cells and circulating tumor DNA (ctDNA). CONCLUSION: This review suggests that the emerging promise of ctDNA may help resolve a crticical dilemma at the heart of breast cancer care, and improve prognostication, treatment selection, and outcomes for patients with breast cancer.

Novel oral selective estrogen receptor degraders (SERDs) to target hormone receptor positive breast cancer: elacestrant as the poster-child.

INTRODUCTION: Estrogen receptor positive (ER+) breast cancer is the most common breast cancer subtype, and therapeutic management relies primarily on inhibiting ER signaling. In the metastatic setting, ER signaling is typically targeted by selective estrogen receptor degraders (SERDs) or aromatase inhibitors (AIs), the latter of which prevent estrogen production. Activating ESR1 mutations are among the most common emergent breast cancer mutations and confer resistance to AIs. AREAS COVERED: Until 2023, fulvestrant was the only approved SERD; fulvestrant is administered intramuscularly, and in some cases may also have limited efficacy in the setting of certain ESR1 mutations. In 2023, the first oral SERD, elacestrant, was approved for use in ESR1-mutated, ER+/HER2- advanced breast cancer and represents a new class of therapeutic options. While the initial approval was as monotherapy, ongoing studies are evaluating elacestrant (as well as other oral SERDs) in combination with other therapies including CDK4/6 inhibitors and PI3K inhibitors, which parallels the current combination uses of fulvestrant. EXPERT OPINION: Elacestrant's recent approval sheds light on the use of biomarkers such as ESR1 to gauge a tumor's endocrine sensitivity. Ongoing therapeutic and correlative biomarker studies will offer new insight and expanding treatment options for patients with advanced breast cancer.

Managing hyperglycemia and rash associated with alpelisib: expert consensus recommendations using the Delphi technique.

Hyperglycemia and rash are expected but challenging adverse events of phosphatidylinositol-3-kinase inhibition (such as with alpelisib). Two modified Delphi panels were conducted to provide consensus recommendations for managing hyperglycemia and rash in patients taking alpelisib. Experts rated the appropriateness of interventions on a 1-to-9 scale; median scores and dispersion were used to classify the levels of agreement. Per the hyperglycemia panel, it is appropriate to start alpelisib in patients with HbA1c 6.5% (diabetes) to <8%, or at highest risk for developing hyperglycemia, if they have a pre-treatment endocrinology consult. Recommend prophylactic metformin in patients with baseline HbA1c 5.7% to 6.4%. Metformin is the preferred first-line anti-hyperglycemic agent. Per the rash panel, initiate prophylactic nonsedating H1 antihistamines in patients starting alpelisib. Nonsedating H1 antihistamines and topical steroids are the preferred initial management for rash. In addition to clinical trial evidence, these recommendations will help address gaps encountered in clinical practice.

HER2 heterogeneity and treatment response-associated profiles in HER2-positive breast cancer in the NCT02326974 clinical trial.

BACKGROUNDHER2-targeting therapies have great efficacy in HER2-positive breast cancer, but resistance, in part due to HER2 heterogeneity (HET), is a significant clinical challenge. We previously described that in a phase II neoadjuvant trastuzumab emtansine (T-DM1) and pertuzumab (P) clinical trial in early-stage HER2-positive breast cancer, none of the patients with HER2-HET tumors had pathologic complete response (pCR).METHODSTo investigate cellular and molecular differences among tumors according to HER2 heterogeneity and pCR, we performed RNA sequencing and ERBB2 FISH of 285 pretreatment and posttreatment tumors from 129 patients in this T-DM1+P neoadjuvant trial. A subset of cases was also subject to NanoString spatial digital profiling.RESULTSPretreatment tumors from patients with pCR had the highest level of ERBB2 mRNA and ERBB signaling. HER2 heterogeneity was associated with no pCR, basal-like features, and low ERBB2 expression yet high ERBB signaling sustained by activation of downstream pathway components. Residual tumors showed decreased HER2 protein levels and ERBB2 copy number heterogeneity and increased PI3K pathway enrichment and luminal features. HET tumors showed minimal treatment-induced transcriptomic changes compared with non-HET tumors. Immune infiltration correlated with pCR and HER2-HET status.CONCLUSIONResistance mechanisms in HET and non-HET tumors are distinct. HER2-targeting antibodies have limited efficacy in HET tumors. Our results support the stratification of patients based on HET status and the use of agents that target downstream components of the ERBB signaling pathway in patients with HET tumors.TRIAL REGISTRATIONClinicalTrials.gov NCT02326974.FUNDINGThis study was funded by Roche and the National Cancer Institute.

Antibody-Drug Conjugate Sacituzumab Govitecan Enables a Sequential TOP1/PARP Inhibitor Therapy Strategy in Patients with Breast Cancer.

PURPOSE: The antibody-drug conjugate (ADC) sacituzumab govitecan (SG) comprises the topoisomerase 1 (TOP1) inhibitor (TOP1i) SN-38, coupled to a monoclonal antibody targeting trophoblast cell surface antigen 2 (TROP-2). Poly(ADP-ribose) polymerase (PARP) inhibition may synergize with TOP1i and SG, but previous studies combining systemic PARP and TOP1 inhibitors failed due to dose-limiting myelosuppression. Here, we assess the proof-of-mechanism and clinical feasibility for SG and talazoparib (TZP) employing an innovative sequential dosing schedule. PATIENTS AND METHODS: In vitro models tested pharmacodynamic endpoints, and in a phase 1b clinical trial (NCT04039230), 30 patients with metastatic triple-negative breast cancer (mTNBC) received SG and TZP in a concurrent (N = 7) or sequential (N = 23) schedule. Outcome measures included safety, tolerability, preliminary efficacy, and establishment of a recommended phase 2 dose. RESULTS: We hypothesized that tumor-selective delivery of TOP1i via SG would reduce nontumor toxicity and create a temporal window, enabling sequential dosing of SG and PARP inhibition. In vitro, sequential SG followed by TZP delayed TOP1 cleavage complex clearance, increased DNA damage, and promoted apoptosis. In the clinical trial, sequential SG/TZP successfully met primary objectives and demonstrated median progression-free survival (PFS) of 7.6 months without dose-limiting toxicities (DLT), while concurrent dosing yielded 2.3 months PFS and multiple DLTs including severe myelosuppression. CONCLUSIONS: While SG dosed concurrently with TZP is not tolerated clinically due to an insufficient therapeutic window, sequential dosing of SG followed by TZP proved a viable strategy. These findings support further clinical development of the combination and suggest that ADC-based therapy may facilitate novel, mechanism-based dosing strategies.