Preclinical activity of sacituzumab govitecan (IMMU-132) in uterine and ovarian carcinosarcomas

Comparative expression of trophoblast cell-surface antigen 2 (TROP2) in the different molecular subtypes of invasive breast carcinoma: An immunohistochemical study of 94 therapy-naive primary breast tumors

BACKGROUND

Sacituzumab govitecan, targeting trophoblast cell-surface antigen 2 (TROP2), is approved for the treatment of triple-negative and hormone receptor-positive/HER2-negative breast cancers. However, detailed studies comparing TROP2 protein expression in the different molecular subtypes of breast cancer are limited, and definitive evidence supporting the use of TROP2 as a biomarker for predicting response to this agent in patients with breast cancer is currently lacking.

OBJECTIVE

To compare the expression of TROP2 in the different molecular subtypes of breast cancer.

METHODS

Immunohistochemical staining for TROP2 was performed on 94 therapy-naive primary invasive breast carcinomas, including 25 luminal A-like, 25 luminal B-like, 19 HER2-like, and 25 triple-negative tumors.

RESULTS

Intermediate to high levels of TROP2 expression were observed in the majority of carcinomas of each molecular subtype, with a wide range of expression in each subtype. Occasional tumors with low or absent TROP2 expression were encountered, including two metaplastic carcinomas which were completely negative for TROP2.

CONCLUSIONS

Our observations support the continued investigation of the efficacy of sacituzumab govitecan in all molecular subtypes of breast carcinoma. Furthermore, the observed wide range of expression of TROP2 suggests that TROP2 may have potential utility as a biomarker for predicting responsiveness to sacituzumab govitecan. If this proves to be the case, then immunohistochemical staining for TROP2 would be critical for identifying those patients whose tumors are completely negative for TROP2, since these patients may be least likely or unlikely to respond to this agent, and alternative therapies may be more appropriate in such instances.

Value of Antibody Drug Conjugates for Gynecological Cancers: A Modern Appraisal Following Recent FDA Approvals

Antibody drug conjugates (ADCs) are a new class of targeted anti-cancer therapies that combine a monoclonal tumor surface receptor-targeting antibody with a highly cytotoxic molecule payload. They enable delivery of cytotoxic therapy more directly to tumor cells and minimize delivery to healthy tissues. This review summarizes the existing literature about ADC therapies approved for use in gynecologic malignancies, relevant preclinical studies, as well as ongoing clinical trials.

Epigenetically upregulating TROP2 and SLFN11 enhances therapeutic efficacy of TROP2 antibody drug conjugate sacitizumab govitecan

TROP2 antibody drug conjugates (ADCs) are under active development. We seek to determine whether we can enhance activity of TROP2 ADCs by increasing TROP2 expression. In metaplastic breast cancers (MpBC), there is limited expression of TROP2, and downregulating transcription factor ZEB1 upregulates E-cad and TROP2, thus sensitizing cancers to TROP2 ADC sacituzumab govitecan (SG). Demethylating agent decitabine decreases DNA methyltransferase expression and TROP2 promoter methylation and subsequently increases TROP2 expression. Decitabine treatment as well as overexpression of TROP2 significantly enhance SG antitumor activity. Decitabine also increases SLFN11, a biomarker of topoisomerase 1 inhibitor (TOP1) sensitivity and is synergistic with SG which has a TOP1 payload, in TROP2-expressing SLFN11-low BC cells. In conclusion, TROP2 and SLFN11 expression can be epigenetically modulated and the combination of demethylating agent decitabine with TROP2 ADCs may represent a novel therapeutic approach for tumors with low TROP2 or SLFN11 expression.

Advances in antibody-drug conjugates for gynecologic malignancies

PURPOSE OF REVIEW

Antibody-drug conjugates (ADCs) represent a new class of drugs that combine a surface receptor-targeting antibody linked to a cytotoxic molecule delivering the potent cytotoxic payload directly to tumor cells. This review summarizes the current literature demonstrating their use in the treatment of gynecologic malignancies.

RECENT FINDINGS

Tisotumab vedotin is the first U.S. Food and Drug Administration (FDA) approved ADC for the treatment of gynecologic cancers. While in the phase 3 randomized controlled trial in platinum resistant ovarian cancer patients, FORWARD 1, mirvetuximab did not meet its primary endpoint of progression-free survival. But we await more recent data from the two ongoing phase 3 trials of mirvetuximab in recurrent ovarian cancer patients. HER2/neu, Napi2b, mesothelin, and human trophoblast cell-surface marker (Trop-2) overexpression have also been exploited as excellent targets by novel ADCs in multiple tumors including ovarian, endometrial, and cervical cancers.

SUMMARY

Current evidence strongly supports the use of ADCs and ongoing clinical trials will provide further information into the potential of making these drugs part of current standard practice allowing patients to be treated with a higher level of personalized cancer care.

Knowledge atlas of antibody-drug conjugates on CiteSpace and clinical trial visualization analysis

Objective

Antibody-drugs conjugates (ADCs) are novel drugs with highly targeted and tumor-killing abilities and developing rapidly. This study aimed to evaluate drug discovery and clinical trials of and explore the hotspots and frontiers from 2012 to 2022 using bibliometric methods.

Methods

Publications on ADCs were retrieved between 2012 and 2022 from Web of Science (WoS) and analyzed with CiteSpace 6.1.R2 software for the time, region, journals, institutions, etc. Clinical trials were downloaded from clinical trial.org and visualized with Excel software.

Results

A total of 696 publications were obtained and 187 drug trials were retrieved. Since 2012, research on ADCs has increased year by year. Since 2020, ADC-related research has increased dramatically, with the number of relevant annual publications exceeding 100 for the first time. The United States is the most authoritative and superior country and region in the field of ADCs. The University of Texas MD Anderson Cancer Center is the most authoritative institution in this field. Research on ADCs includes two clinical trials and one review, which are the most influential references. Clinical trials of ADCs are currently focused on phase I and phase II. Comprehensive statistics and analysis of the published literature and clinical trials in the field of ADCs, have shown that the most studied drug is brentuximab vedotin (BV), the most popular target is human epidermal growth factor receptor 2 (HER2), and breast cancer may become the main trend and hotspot for ADCs indications in recent years.

Conclusion

Antibody-drug conjugates have become the focus of targeted therapies in the field of oncology. The innovation of technology and combination application strategy will become the main trend and hotspots in the future.

A literature review of the promising future of TROP2: a potential drug therapy target

Background and Objective

Previous studies have demonstrated that the oncogene trophoblast cell surface antigen 2 (TROP2) has great application prospects as a therapeutic target. However, few literature reviews have systematically summarized and evaluated its role in cancer therapy. This study aims to summarize the molecular structure, functions, signal transduction pathways, and prognostic value of TROP2, and explore therapeutic agents that target TROP2.

Methods

A total of 1,376 published literatures from PubMed and 614 published literatures from EMBASE were retrieved by searching "TROP2" or "Trophoblast cell surface antigen 2". The search was conducted on December 12, 2020, and updated on November 20, 2022. The cBioportal and GEPIA (Gene Expression Profiling Interactive Analysis) databases were used to analyze the expression, mutation, and prognostic value of TROP2 in different types of cancer.

Key Content and Findings

TROP2 is overexpressed in different tumor tissues and plays roles in cell proliferation, invasion, migration, apoptosis, and treatment resistance by binding to or interacting with several molecules. As a therapeutic target, TROP2 is particularly suitable for antibody-based therapies. Monoclonal antibodies, bispecific antibodies, antibody-drug conjugates (ADCs), virus-like particles, and antibody drugs in combination with traditional chemotherapy, immunotherapy, radioimmunotherapy, photoimmunotherapy, and nanoparticles that target TROP2 have thus far been rapidly developed. For example, sacituzumab govitecan (IMMU-132), a TROP2-targeting ADC, was granted accelerated approval for the treatment of metastatic triple-negative breast cancer (TNBC). Anti-TROP2 antibody-conjugated nanoparticles (ST-NPs) are a promising vehicle for delivering doxorubicin in targeted TNBC therapy.

Conclusions

The availability of TROP2-targeting ADCs makes TROP2 an accessible and promising therapeutic target for advanced metastatic cancers. The present review describes the important role of TROP2 in tumorigenesis and its potential applications as a promising biomarker and therapeutic target that is capable of reversing resistance.

Role of sacituzumab govitecan in solid tumors

OBJECTIVE

To evaluate the antibody-drug conjugate- sacituzumab govitecan, its pharmacological properties, toxicity, data supporting efficacy against a wide variety of solid tumors beyond breast cancer, and potential future uses.

DATA SOURCES

Articles in MEDLINE/PubMed databases and the National Institutes of Health Clinical Trials Registry (http://www. clinicaltrials.gov) between January 1, 2015, and July 1, 2021 using MeSH terms sacituzumab govitecan(- hziy) and solid tumors were reviewed.

DATA SUMMARY

Antibody-drug conjugates (ADC's) are a subclass of emerging cancer therapeutics which combines chemotherapy with targeted antibodies. Sacituzumab govitecan (SG) is a novel antibody drug conjugate that has recently been approved by the Food and Drug Administration (FDA) in adult patients for the treatment of unresectable locally advanced or metastatic triple-negative breast cancer (mTNBC) who have received two or more prior systemic therapies, at least one of them for metastatic disease. The approval of sacituzumab govitecan provides a new option for solid tumors that need to be further explored. In this review article, we discussed the pharmacokinetics, pharmacodynamics, safety profile of sacituzumab govitecan and various ongoing clinical trials on sacituzumab govitecan.

CONCLUSION

Sacituzumab is a significant advancement made in cancer therapy. SG has showed significantly improved Health-related quality of life (HRQoL) in addition to prolonged progression free survival and Over all survival in addition to maintaining a good safety profile. Multiple clinical trials on SG are ongoing to evaluate the potential use of SG as neoadjuvant therapy in triple negative breast cancer, as an Adjuvant therapy, in combination with immunotherapy, and also for various solid tumors.

Sacituzumab Govitecan-hziy in Breast Cancer

Trophoblast cell-surface antigen-2 (Trop-2) is a transmembrane calcium signal transducer and its overexpression is common in many types of malignant epithelial tumors, including breast cancer (BC). Sacituzumab govitecan-hziy (SG), the anti-Trop-2 antibody-drug conjugate, resulted in a significant survival benefit over chemotherapy in patients with metastatic triple-negative breast cancer (mTNBC). The greatest efficacy was observed in those who had a medium or high Trop-2 score. However, the importance of Trop-2 as a potential predictive factor requires further research. Elderly patients also appear to benefit from treating with SG. While the early results are encouraging, the ultimate benefit of SG in patients with brain metastases has yet to be determined. Early phase studies have shown that SG is also active in hormone receptor-positive/human epidermal growth factor receptor 2-negative (HR+/HER2-) metastatic BC. The most common side effects of SG are nausea, neutropenia and diarrhea. Currently, several clinical trials are in progress with SG in monotherapy and in combination treatment for various types of BC. Taken together, SG should be considered as a new standard of care in patients with pretreated mTNBC. This review summarizes the development and highlights recent advances of the SG in BC.

Sacituzumab govitecan as second-line treatment for metastatic triple-negative breast cancer-phase 3 ASCENT study subanalysis

Patients with triple-negative breast cancer (TNBC) who relapse early after (neo)adjuvant chemotherapy have more aggressive disease. In the ASCENT trial, sacituzumab govitecan (SG), an antibody-drug conjugate composed of an anti-Trop-2 antibody coupled to SN-38 via a hydrolyzable linker, improved outcomes over single-agent chemotherapy of physician's choice (TPC) in metastatic TNBC (mTNBC). Of 468 patients without known baseline brain metastases, 33/235 vs 32/233 patients (both 14%) in the SG vs TPC arms, respectively, received one line of therapy in the metastatic setting and experienced disease recurrence ≤12 months after (neo)adjuvant chemotherapy. SG prolonged progression-free survival (median 5.7 vs 1.5 months [HR, 0.41; 95% CI, 0.22-0.76]) and overall survival (median 10.9 vs 4.9 months [HR, 0.51; 95% CI, 0.28-0.91]) vs TPC, with a manageable safety profile in this subgroup consistent with the overall population. In this second-line setting, as with later-line therapy, SG improved survival over conventional chemotherapy for patients with mTNBC.

The European Medicines Agency review of sacituzumab govitecan for the treatment of triple-negative breast cancer

Sacituzumab govitecan (SG) is an antineoplastic agent which combines a humanized monoclonal antibody binding to trophoblast cell surface antigen-2 (Trop-2)-expressing cancer cells, linked with cytotoxic moiety SN-38 (govitecan) with topoisomerase I inhibitor action. On 22 November 2021, a marketing authorization valid through the European Union (EU) was issued under the European Medicines Agency (EMA)’s accelerated assessment program for SG as monotherapy for the treatment of adult patients with unresectable or metastatic triple-negative breast cancer (mTNBC) who have received two or more prior systemic therapies, including at least one of them for advanced disease. The assessment was based on results from an open-label, randomized, phase III trial to evaluate the safety, tolerability, pharmacokinetics and efficacy of SG versus treatment of physician’s choice (TPC) in patients with mTNBC who received at least two prior treatments including at least one of them for advanced disease. The efficacy results in the overall population, based on mature data, showed a statistically significant improvement of SG over TPC in progression-free survival (PFS) and overall survival (OS). The median PFS was 4.8 months versus 1.7 months [hazard ratio (HR) = 0.43, n = 529; 95% CI 0.35-0.54; P < 0.0001] and the median OS was 11.8 months versus 6.9 months (HR = 0.51, n = 529; 95% CI 0.41-0.62; P < 0.0001). The most common (>30%) side effects of SG were diarrhea, neutropenia, nausea, fatigue, alopecia, anemia, constipation and vomiting. The aim of this manuscript is to summarize the scientific review of the application leading to regulatory approval in the EU.

•

Trodelvy (SG) received a marketing authorization valid throughout the EU on 22 November 2021.

•

SG is indicated for adults with unresectable or metastatic TBNC.

•

SG is an antibody–drug conjugate considered a first-in-class medicine.

•

SG prolonged OS and PFS ∼5 and 3 months, respectively, when compared to TPC.

•

The most common serious side effects are febrile neutropenia and diarrhea.

Analysis of patients without and with an initial triple-negative breast cancer diagnosis in the phase 3 randomized ASCENT study of sacituzumab govitecan in metastatic triple-negative breast cancer

PURPOSE

Sacituzumab govitecan (SG) is an antibody-drug conjugate composed of an anti-Trop-2 antibody coupled to SN-38 via a proprietary hydrolyzable linker. In the ASCENT study, SG improved survival versus single-agent treatment of physician's choice (TPC) in pre-treated metastatic triple-negative breast cancer (mTNBC). Hormone/HER2 receptor changes are common, particularly at relapse/metastasis. This subanalysis assessed outcomes in patients who did/did not have TNBC at initial diagnosis, before enrollment.

METHODS

TNBC diagnosis was only required at study entry. Patients with mTNBC refractory/relapsing after ≥ 2 prior chemotherapies were randomized 1:1 to receive SG or TPC. Primary endpoint was progression-free survival (PFS) in patients without brain metastases.

RESULTS

Overall, 70/235 (30%) and 76/233 (33%) patients who received SG and TPC, respectively, did not have TNBC at initial diagnosis. Clinical benefit with SG versus TPC was observed in this subset. Median PFS was 4.6 versus 2.3 months (HR 0.48; 95% CI 0.32-0.72), median overall survival was 12.4 versus 6.7 months (HR 0.44; 95% CI 0.30-0.64), and objective response rate (ORR) was 31% versus 4%; those who also received prior CDK4/6 inhibitors had ORRs of 21% versus 5%. Efficacy and safety for patients with TNBC at initial diagnosis were generally similar to those who did not present with TNBC at initial diagnosis.

CONCLUSION

Patients without TNBC at initial diagnosis had improved clinical outcomes and a manageable safety profile with SG, supporting SG as a treatment option for mTNBC regardless of subtype at initial diagnosis. Subtype reassessment in advanced breast cancer allows for optimal treatment. Clinical trial registration number NCT02574455, registered October 12, 2015.

Diazaborines Are a Versatile Platform to Develop ROS-Responsive Antibody Drug Conjugates*

Antibody-drug conjugates (ADCs) are a new class of therapeutics that combine the lethality of potent cytotoxic drugs with the targeting ability of antibodies to selectively deliver drugs to cancer cells. In this study we show for the first time the synthesis of a reactive-oxygen-species (ROS)-responsive ADC (VL-DAB31-SN-38) that is highly selective and cytotoxic to B-cell lymphoma (CLBL-1 cell line, IC₅₀ value of 54.1 nM). The synthesis of this ADC was possible due to the discovery that diazaborines (DABs) are a very effective ROS-responsive unit that are also very stable in buffer and in plasma. DFT calculations performed on this system revealed a favorable energetic profile (ΔGR=-74.3 kcal mol^-1 ) similar to the oxidation mechanism of aromatic boronic acids. DABs' very fast formation rate and modularity enabled the construction of different ROS-responsive linkers featuring self-immolative modules, bioorthogonal functions, and bioconjugation handles. These structures were used in the site-selective functionalization of a VL antibody domain and in the construction of the homogeneous ADC.

Trop-2 Therapy in Metastatic Triple-Negative Breast Cancer in Italy: Clinical Opportunity and Regulatory Pitfalls

Trop-2 is an ideal candidate for targeted therapeutics because it is a transmembrane protein with an extracellular domain overexpressed in a wide variety of tumors, and is upregulated in normal cells. Consequently, several Trop-2-targeted drugs have recently been developed for clinical use, such as anti-Trop-2 antibodies. Sacituzumab govitecan, a Trop-2-directed antibody and topoisomerase inhibitor drug conjugate, was recently approved by the Food and Drug Administration (FDA) and European Medicines Agency (EMA) for the treatment of metastatic triple-negative breast cancer and metastatic urothelial cancer. In Italy, this treatment cannot be used in clinical practice because it has not yet been approved by the Agenzia Italiana del Farmaco (AIFA, Rome, Italy). In Italy, this is not a new problem, in fact, when a new compound is approved by the U.S. and Europe, there is often a delay in its approval for use. The adoption of universal guidelines and the standardization of Trop-2 evaluation is urgently needed.

First-in-Human Study of PF-06647020 (Cofetuzumab Pelidotin), an Antibody-Drug Conjugate Targeting Protein Tyrosine Kinase 7, in Advanced Solid Tumors

PURPOSE

We investigated safety, tolerability, pharmacokinetics, and antitumor activity of the protein tyrosine kinase 7 (PTK7)-targeted, auristatin-based antibody-drug conjugate (ADC) PF-06647020/cofetuzumab pelidotin (NCT02222922).

PATIENTS AND METHODS

Patients received PF-06647020 intravenously every 3 weeks at 0.2-3.7 mg/kg or every 2 weeks at 2.1-3.2 mg/kg, in sequential dose escalation, following a modified toxicity probability interval method. In dose expansion, pretreated patients with advanced, platinum-resistant ovarian cancer, non-small cell lung cancer (NSCLC), or triple-negative breast cancer (TNBC) received PF-06647020 2.8 mg/kg every 3 weeks.

RESULTS

The most common, treatment-related adverse events for PF-06647020 administered every 3 weeks were nausea, alopecia, fatigue, headache, neutropenia, and vomiting (45%-25%); 25% of patients had grade ≥ 3 neutropenia. Two patients experienced dose-limiting toxicities (grade 3 headache and fatigue) at the highest every 3 weeks dose evaluated. The recommended phase II dose was 2.8 mg/kg every 3 weeks. The overall safety profile observed with PF-06647020 administered every 2 weeks was similar to that of the every 3 weeks regimen. Systemic exposure for the ADC and total antibody generally increased in a dose-proportional manner. Antitumor activity was observed in treated patients with overall objective response rates of 27% in ovarian cancer (n = 63), 19% in NSCLC (n = 31), and 21% in TNBC (n = 29). Responders tended to have moderate or high PTK7 tumor expression by IHC.

CONCLUSIONS

This PTK7-targeted ADC demonstrated therapeutic activity in previously treated patients with ovarian cancer, NSCLC, and TNBC at a dose range of 2.1-3.2 mg/kg, supporting further clinical evaluation to refine dose, schedule, and predictive tissue biomarker testing in patients with advanced malignancies.

Biomarker analyses in the phase III ASCENT study of sacituzumab govitecan versus chemotherapy in patients with metastatic triple-negative breast cancer

BACKGROUND

The pivotal phase III ASCENT trial demonstrated improved survival outcomes associated with sacituzumab govitecan (SG), an anti-trophoblast cell-surface antigen 2 (anti-Trop-2) antibody-drug conjugate linked with the topoisomerase-inhibitor SN-38, over single-agent chemotherapy treatment of physician's choice (TPC) in previously treated metastatic triple-negative breast cancer (mTNBC). This prespecified, exploratory biomarker analysis from the ASCENT trial evaluates the association between tumor Trop-2 expression and germline BRCA1/2 mutation status with clinical outcomes.

PATIENTS AND METHODS

Patients with mTNBC refractory to or progressing after two or more prior chemotherapies, with one or more in the metastatic setting, were randomized to receive SG (10 mg/kg intravenously days 1 and 8, every 21 days) or TPC (capecitabine, eribulin, vinorelbine, or gemcitabine) until disease progression/unacceptable toxicity. Biopsy or surgical specimens were collected at study entry to determine Trop-2 expression level using a validated immunohistochemistry assay and histochemical scoring. Germline BRCA1/2 mutation status was collected at baseline.

RESULTS

Of 468 assessable patients, 290 had Trop-2 expression data [64% (n = 151 SG) versus 60% (n = 139 TPC)] and 292 had known BRCA1/2 mutation status [63% (n = 149 SG) versus 61% (n = 143 TPC)]. Median progression-free survival in SG- versus TPC-treated patients was 6.9, 5.6, and 2.7 months versus 2.5, 2.2, and 1.6 months for high, medium, and low Trop-2 expression, respectively. Median overall survival (14.2, 14.9, and 9.3 months versus 6.9, 6.9, and 7.6 months) and objective response rates (44%, 38%, and 22% versus 1%, 11%, and 6%) were numerically higher with SG versus TPC in patients with high, medium, and low Trop-2 expression, respectively. Efficacy outcomes were numerically higher with SG versus TPC in patients with and without germline BRCA1/2 mutations.

CONCLUSIONS

SG benefits patients with previously treated mTNBC expressing high/medium Trop-2 compared with standard-of-care chemotherapy and regardless of germline BRCA1/2 mutation status. The small number of patients with low Trop-2 expression precludes definitive conclusions on the benefit of SG in this subgroup.

Uterine carcinosarcoma: An overview

Uterine carcinosarcoma (UCS), also known as malignant mixed Müllerian tumor, is a rare gynecological malignancy characterized by poor prognosis. This "biphasic" neoplasm presents an admixture of epithelial and mesenchymal/sarcomatoid tumor cells which partially share their molecular signature and exhibit a typical epithelial-to-mesenchymal transition gene expression profile. Due to the rarity of this cancer, at present there is a scarcity of specific treatment guidelines. Surgical resection remains the best curative option for localized disease, whereas the addition of peri-operative radiotherapy, chemotherapy and chemoradiation has been shown to further improve disease outcomes. In the metastatic setting, palliative chemotherapy is currently the treatment of choice, although no consensus exists about the best regimen to be delivered. Besides standard treatment options for the advanced disease, mechanistic insights into UCS pathogenesis and identification of its histopathological and molecular features boosted the development of novel, and potentially more effective, therapeutic agents, that will be here discussed.

Perspectives of nano-carrier drug delivery systems to overcome cancer drug resistance in the clinics

Advanced cancer is still considered an incurable disease because of its metastatic spread to distal organs and progressive gain of chemoresistance. Even though considerable treatment progress and more effective therapies have been achieved over the past years, recurrence in the long-term and undesired side effects are still the main drawbacks of current clinical protocols. Moreover, a majority of chemotherapeutic drugs are highly hydrophobic and need to be diluted in organic solvents, which cause high toxicity, in order to reach effective therapeutic dose. These limitations of conventional cancer therapies prompted the use of nanomedicine, the medical application of nanotechnology, to provide more effective and safer cancer treatment. Potential of nanomedicines to overcome resistance, ameliorate solubility, improve pharmacological profile, and reduce adverse effects of chemotherapeutical drugs is thus highly regarded. Their use in the clinical setting has increased over the last decade. Among the various existing nanosystems, nanoparticles have the ability to transform conventional medicine by reducing the adverse effects and providing a controlled release of therapeutic agents. Also, their small size facilitates the intracellular uptake. Here, we provide a closer review of clinical prospects and mechanisms of action of nanomedicines to overcome drug resistance. The significance of specific targeting towards cancer cells is debated as well.

Sacituzumab govitecan, a Trop-2-directed antibody-drug conjugate, for patients with epithelial cancer: final safety and efficacy results from the phase I/II IMMU-132-01 basket trial

BACKGROUND

Sacituzumab govitecan (SG), a trophoblast cell surface antigen-2 (Trop-2)-directed antibody-drug conjugate, has demonstrated antitumor efficacy and acceptable tolerability in a phase I/II multicenter trial (NCT01631552) in patients with advanced epithelial cancers. This report summarizes the safety data from the overall safety population (OSP) and efficacy data, including additional disease cohorts not published previously.

PATIENTS AND METHODS

Patients with refractory metastatic epithelial cancers received intravenous SG (8, 10, 12, or 18 mg/kg) on days 1 and 8 of 21-day cycles until disease progression or unacceptable toxicity. Endpoints for the OSP included safety and pharmacokinetic parameters with investigator-evaluated objective response rate (ORR per RECIST 1.1), duration of response, clinical benefit rate, progression-free survival, and overall survival evaluated for cohorts (n > 10 patients) of small-cell lung, colorectal, esophageal, endometrial, pancreatic ductal adenocarcinoma, and castrate-resistant prostate cancer.

RESULTS

In the OSP (n = 495, median age 61 years, 68% female; UGT1A1∗28 homozygous, n = 46; 9.3%), 41 (8.3%) permanently discontinued treatment due to adverse events (AEs). Most common treatment-related AEs were nausea (62.6%), diarrhea (56.2%), fatigue (48.3%), alopecia (40.4%), and neutropenia (57.8%). Most common treatment-related serious AEs (n = 75; 15.2%) were febrile neutropenia (4.0%) and diarrhea (2.8%). Grade ≥3 neutropenia and febrile neutropenia occurred in 42.4% and 5.3% of patients, respectively. Neutropenia (all grades) was numerically more frequent in UGT1A1∗28 homozygotes (28/46; 60.9%) than heterozygotes (69/180; 38.3%) or UGT1A1∗1 wild type (59/177; 33.3%). There was one treatment-related death due to an AE of aspiration pneumonia. Partial responses were seen in endometrial cancer (4/18, 22.2% ORR) and small-cell lung cancer (11/62, 17.7% ORR), and one castrate-resistant prostate cancer patient had a complete response (n = 1/11; 9.1% ORR).

CONCLUSIONS

SG demonstrated a toxicity profile consistent with previous published reports. Efficacy was seen in several cancer cohorts, which validates Trop-2 as a broad target in solid tumors.

Sacituzumab Govitecan: First Approval

Sacituzumab govitecan (sacituzumab govitecan-hziy; Trodelvy™) is a Trop-2-directed antibody conjugated to a topoisomerase I inhibitor (SN-38) that is being developed by Immunomedics for the treatment of solid tumours, including breast cancer. In April 2020, sacituzumab govitecan received accelerated approval in the USA for the treatment of adult patients with metastatic triple-negative breast cancer (mTNBC) who have received at least two prior therapies for metastatic disease. Sacituzumab govitecan is undergoing phase III development for breast cancer in the USA and EU, and phase II development for urothelial cancer. It is also being explored for brain metastases, glioblastoma, endometrial cancer and prostate cancer. This article summarizes the milestones in the development of sacituzumab govitecan leading to this first approval for mTNBC.

Novel antibody-drug conjugates: current and future roles in gynecologic oncology

PURPOSE OF REVIEW

Antibody-drug conjugates (ADCs) represent a new class of drugs that combine a surface receptor-targeting antibody linked to a cytotoxic molecule. This review summarizes the current literature demonstrating their tremendous promise as therapeutic agents in the treatment of aggressive gynecologic malignancies.

RECENT FINDINGS

Several antigens have proven to be differentially overexpressed in a variety of gynecologic tumors when compared with normal surrounding tissue and serve as novel targets for ADC therapy. In the last few years HER2/neu, folic acid-alpha (FRα) and Trop-2 overexpression have been exploited as excellent targets by novel ADCs such as Trastuzumab emtansine (T-DM1), SYD985, IMGN853 (Mirvetuximab soravtansine) and Sacituzumab govitecan (SG, IMMU-132) in multiple tumors including ovarian, endometrial and cervical cancers. Although the selectivity of ADCs with noncleavable linkers (i.e. T-DM1) has shown negligible effect on surrounding antigen negative cells, those ADCs with cleavable linkers (i.e. SYD985, IMGN853 and SG) may kill both antigen-positive target cells and surrounding antigen-negative cells via the bystander effect.

SUMMARY

Preclinical data strongly supports these ADCs and ongoing clinical trials will shed further light into the potential of making these drugs part of current standard practice and providing our patients with a higher level of personalized cancer care.

Trop2: Jack of All Trades, Master of None

Trophoblast cell surface antigen 2 (Trop2) is a widely expressed glycoprotein and an epithelial cell adhesion molecule (EpCAM) family member. Although initially identified as a transmembrane protein, other subcellular localizations and processed forms were described. Its congenital mutations cause a gelatinous drop-like corneal dystrophy, a disease characterized by loss of barrier function in corneal epithelial cells. Trop2 is considered a stem cell marker and its expression associates with regenerative capacity in various tissues. Trop2 overexpression was described in tumors of different origins; however, functional studies revealed both oncogenic and tumor suppressor roles. Nevertheless, therapeutic potential of Trop2 was recognized and clinical studies with drug-antibody conjugates have been initiated in various cancer types. One of these agents, sacituzumab govitecan, has been recently granted an accelerated approval for therapy of metastatic triple-negative breast cancer. In this article, we review the current knowledge about the yet controversial function of Trop2 in homeostasis and pathology.

Sacituzumab Govitecan-hziy: An Antibody-Drug Conjugate for the Treatment of Refractory, Metastatic, Triple-Negative Breast Cancer

OBJECTIVE

To review the pharmacology, efficacy, and safety of sacituzumab govitecan (-hziy; IMMU-132, Trodelvy) for patients with metastatic triple-negative breast cancer (mTNBC) who have received at least 2 prior therapies for metastatic disease.

DATA SOURCES

A literature search was conducted utilizing PubMed and MEDLINE databases, applicable published abstracts, and ongoing studies from ClinicalTrials.gov between January 1, 1981, and September 3, 2020. Keywords included sacituzumab govitecan (-hziy), IMMU-132, Trop-2 (trophoblast cell-surface antigen 2), and TACSTD2.

STUDY SELECTION AND DATA EXTRACTION

All English-language trials involving sacituzumab govitecan for mTNBC were included and discussed.

DATA SYNTHESIS

Sacituzumab govitecan is an antibody-drug conjugate targeted for Trop-2 and conjugated to the topoisomerase-1 inhibitor SN-38. It was granted accelerated Food and Drug Administration approval based on a phase I/II single-arm, multicenter study (n = 108), which reported an overall response rate of 33.3% and median duration of response of 7.7 months (95% CI = 4.9-10.8 months). Common adverse reactions include nausea, neutropenia, diarrhea, fatigue, anemia, vomiting, alopecia, constipation, rash, decreased appetite, abdominal pain, and respiratory infection. A confirmatory, randomized phase III clinical trial is ongoing (NCT02574455).

RELEVANCE TO PATIENT CARE AND CLINICAL PRACTICE

This review covers the efficacy, safety, and clinical use of sacituzumab govitecan, a third-line drug with activity in mTNBC.

CONCLUSION

Sacituzumab govitecan is a novel targeted treatment with promising activity in mTNBC.

An overview of antibody-drug conjugates in oncological practice

Antibody–drug conjugates (ADCs) are designed to manipulate the toxic efficacy of specific chemotherapeutic compounds, employing the high affinity of antibody-mediated delivery so as to drive them selectively to target cancer cells. These immunoconjugates encompass the general tendency towards precision medicine and avert the systemic toxicities of conventional chemotherapy, accomplishing an improved therapeutic index. Cumulative experience acquired from first-generation ADCs offers new perspectives to these promising therapeutic modalities for various hematological and solid cancers and propels their clinical development in a faster-than-ever pace, as indicated by the approval of four novel ADCs during the last year. This paper aims to provide an up-to-date overview of the eight ADCs approved by the US Food and Drug Administration and their current indications in oncological practice. Starting from their bio-pharmaceutical background, we track their clinical evolution, with an emphasis on the pivotal trials that led to their commercial release. Late-stage studies examining these eight ADCs in other-than-approved settings as well as the investigation of potential new candidates are also reviewed. In the close future, more data are expected to expand ADCs’ oncological utility and to further reshape their role in cancer therapeutics.