Antibody-Drug Conjugates in Breast Cancer: A Comprehensive Review of How to Selectively Deliver Payloads

Antibody-drug conjugates (ADCs) have surfaced as a promising group of anticancer agents employing the precise targeting capacity of monoclonal antibodies to transport highly effective cytotoxic payloads. Compared to conventional chemotherapy, they aim to selectively eradicate cancer cells while minimizing off-target toxicity on healthy tissues. An increasing body of evidence has provided support for the efficacy of ADCs in treating breast cancer across various contexts and tumor subtypes, resulting in significant changes in clinical practice. Nevertheless, unlocking the full potential of these therapeutic agents demands innovative molecular designs to address complex clinical challenges, including drug resistance, tumor heterogeneity, and treatment-related adverse events. This thorough review provides an in-depth analysis of the clinical data on ADCs, offering crucial insights from pivotal clinical trials that assess the efficacy of ADCs in diverse breast cancer settings. This aids in providing a comprehensive understanding of the current state of ADCs in breast cancer therapy, while also providing valuable perspectives for the future.

Abstract PS6-25: Cts5 tested in a Brazilian population: A tool that can predict global survival in early breast cancer ER+/HER2-, as well as the response to extended endocrine therapy

Background: Breast cancer (BC) accounts for 30% of female cancer, is the most commonly diagnosed cancer worldwide and the second most common cause of cancer-related deaths among females. The majority (79%) of breast cancers express the estrogen receptor (ER+) and 91% of them are diagnosed at an early stage. But it is also known that late recurrence (5 years or more after diagnosis) represents about 50% of all recurrences of ER+ BC. Identify those patients who are at greatest risk for late recurrence and develop strategies to prevent it has emerged as a major unmet need in ER+ BC. In an attempt to reduce late recurrences, several studies have recently proposed that endocrine therapy (ET) prolonged beyond five years would achieve this goal. Conversely, extended ET increases the rates of side-effects, compared to conventional ET. Therefore, selecting patients who would really benefit from extended ET is crucial, as this would spare low-risk patients from potentially greater side effects and impacts in quality of life, restricting the treatment only for those who really could take advantage of this approach. That is why, currently, the subject late recurrence is being studied so much. CTS 5 (Clinical Treatment Score after 5 years) is a simple clinical-pathological tool developed to estimate the residual risk of distant recurrence after 5 years of ET.

Objective: To assess the prognostic and predictive impact of CTS5 in overall survival (OS) of ER+BC patients treated with conventional or extended ET in a Brazilian Cancer Center.

Study design and statistical analysis: A retrospective cohort study was conducted, selecting, through administrative databases of AC Camargo Cancer Center, 1085 ER+ BC patients with at least 5 years of adjuvant ET. Patients who missed follow-up before completing ET were excluded, but we kept those who presented any event related to illness or treatment. Statistical analysis includes a Kaplan-Meier analysis and the Log Rank test. Prognostic factors were assessed using univariate and multivariate Cox analysis.

Results: The demographic and clinical characteristics of patients are described in table 1. In this cohort, continuous CTS5 was a significant predictor for OS (HR = 4,49 [3.12-6.46], p<0.001). In addition, in the high CTS5 group a significant benefit was observed with prolongation of adjuvant ET beyond 5 years (HR = 4,91 [3.41-7.06], p<0.001), not observed for low and intermediate risks.

Conclusion: In this cohort, composed of real-life Brazilian women with ER+/ HER2- BC, irrespective of menopausal status, CTS5 proved to be an excellent predictor of OS. In addition, it was shown to be a predictor of response to extended ET. CTS5 score can identify a group of high-risk patients who benefits from extended ET.

We consider that it would be of great value to expand the study population and follow-up, especially to analyze whether this tool also has a predictive value in contraindicating extended ET in low- risk and intermediate-risk patients.

Table 1. Demographic and Clinical CharacteristicsCharacteristicNo. (%)Age, yearsMedian53IQR26-91< 50 years446 (41.1)>50 years639 (58.9)Tumor size, mm≤ 10285 (24.1)10-20458 (38.7)20-50378 (31.9)>5060 (5.1)GradeWell142 (11,9)Intermediate385 (32,5)Poor654 (55,2)Nodal status (No. of positive nodes)0756 (64.0)1 -3305 (25.8)≥4120 (10.2)ChemotherapyAdjuvant592 (50.1)Neoadjuvant118 (10.0)Endocrine TerapyET 5 years1060 (89,7)ET extendend100 (8.4)ET for less than 5 years.21 (1,8)CTS5Low587 (49.6)Intermediate344 (29.1)High250 (21.1)RecurrenceDistant147 (12,4)Local 39 (3,3)

Citation Format: Lucas Vian, Ronaldo Souza, Vladmir Claudio Cordeiro de Lima, Daniella Yumi Tsuji Honda, Samara Theodoro Pacheco, Caio Dabbous de Liz, Luciana Beatriz Mendes Gomes, Bruno Cezar Mendonça Uchôa Júnior, Paula Tavares Guimarães, Celso Silva e Souza Filho, Andréa Paiva Guimarães, Maria Fernanda Evangelista Simões, Mauro Daniel Spina Donadio, Angelo Bezerra de Souza Fêde, Augusto Obuti Saito, Adriana Regina Gonçalves Ribeiro, Joyce Maria Lisboa Maia, Iara Karoline Freire Lustosa, Fabricio de Souza Castro, Monique Celeste Tavares, Marcelle Goldner Cesca, Marcelo Corassa, Noam Falbel Pondé, Solange Sanches. Cts5 tested in a Brazilian population: A tool that can predict global survival in early breast cancer ER+/HER2-, as well as the response to extended endocrine therapy [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr PS6-25.

Gabapentin for the prevention of chemotherapy- induced nausea and vomiting: a pilot study

INTRODUCTION

Chemotherapy-induced nausea and vomiting (CINV) is a distressing side effect that affects many patients undergoing emetogenic chemotherapy, despite the use of antiemetic medications. The purpose of this trial was to evaluate the efficacy and safety of gabapentin for the prevention of CINV during the first cycle of treatment in patients receiving moderately or highly emetogenic chemotherapy.

METHODS

Eighty chemotherapy-naive patients, scheduled to receive moderately and highly emetogenic chemotherapy, were enrolled in this randomised, double-blind, placebo-controlled clinical trial. All patients received intravenous ondansetron 8 mg, dexamethasone 10 mg and ranitidine 50 mg before chemotherapy on day 1 and oral dexamethasone 4 mg twice a day on days 2 and 3. Patients were randomly assigned to take gabapentin 300 mg or placebo on the following schedule: 5 and 4 days before chemotherapy once daily, 3 and 2 days before chemotherapy twice daily, 1 day before to 5 days after chemotherapy thrice daily. The primary endpoint was complete overall protection from both vomiting and nausea over the course of the entire study (day 1 through day 5), and complete protection during the delayed period (24-120 h after chemotherapy).

RESULTS

The proportion of patients achieving complete response improved from 40% to 62.5%, (p = 0.04) when comparing the control group and the gabapentin group, respectively. In the subset of patients who achieved complete control in the acute phase, the percentage of patients who achieved delayed complete control was higher in the gabapentin group (89.3 × 60.7%, p = 0.01). Adverse events did not significantly differ between study arms.

CONCLUSIONS

Gabapentin is a low-cost strategy to improve complete control of CINV, specially delayed CINV control.

Multivitamins do not improve radiation therapy-related fatigue: results of a double-blind randomized crossover trial

BACKGROUND

Fatigue is a common symptom in cancer patients receiving radiation therapy.

PATIENTS AND METHODS

We conducted a double-blind randomized crossover trial of multivitamins versus placebo in patients with breast cancer undergoing radiation therapy to evaluate fatigue and quality of life.

RESULTS

: We randomized 40 patients to either placebo or Centrum Silver. At the middle of the radiation treatments, patients were switched from placebo to multivitamins and vice versa. Patients answered the EORTC QLQ C-30 quality of life (QOL) and Chalder fatigue questionnaires at the beginning, middle, and end of radiation therapy. Both groups experienced decreases in general (P = 0.009; P = 0.001) and physical fatigue scores (P = 0.031; P = 0.029) at the end of the course of placebo compared with the assessment prior to this treatment. We also observed significant improvements in functional (P = 0.026) and symptoms (P = 0.016) score scales of the QOL questionnaire in the patients on placebo. No significant changes were elicited with the use of multivitamins. We also observed significantly lower rates of fatigue in the patients who had just finished a course of placebo as compared with patients finishing a course of multivitamins (0 vs. 25% P = 0.035).

CONCLUSION

Multivitamins do not improve radiation-related fatigue in patients with breast cancer.