Sacituzumab govitecan (IMMU-132), an anti-Trop-2-SN-38 antibody-drug conjugate for the treatment of diverse epithelial cancers: Safety and pharmacokinetics

Quantifying payloads of antibody‒drug conjugates using a postcolumn infused-internal standard strategy with LC‒MS

BACKGROUND

Antibody‒drug conjugates (ADCs) are innovative biopharmaceutics consisting of a monoclonal antibody, linkers, and cytotoxic payloads. Monitoring circulating payload concentrations has the potential to identify ADC toxicity; however, accurate quantification faces challenges, including low plasma concentrations, severe matrix effects, and the absence of stable isotope-labeled internal standards (SIL-IS) for payloads and their derivatives. Previous studies used structural analogs as internal standards, but different retention times between structural analogs and target analytes may hinder effective matrix correction. Therefore, a more flexible approach is required for precise payload quantification.

RESULTS

We developed an LC‒MS/MS method incorporating a postcolumn-infused internal standard (PCI-IS) strategy for quantifying payloads and their derivatives of trastuzumab emtansine, trastuzumab deruxtecan, and sacituzumab govitecan, including DM1, MCC-DM1, DXd, SN-38, and SN-38G. Structural analogs (maytansine, Lys-MCC-DM1, and exatecan) were selected as PCI-IS candidates, and their accuracy performance was evaluated based on the percentage of samples within 80%-120% quantification accuracy. Compared to the approach without PCI-IS correction, exatecan enhanced the accuracy performance from 30-40%-100% for SN-38 and DXd, while maytansine and Lys-MCC-DM1 showed comparable accuracy for DM1 and MCC-DM1. This validated PCI-IS analytical method showed superior normalization of matrix effect in all analytes compared to the conventional internal standard approach. The clinical application of this approach showed pronounced differences in DXd and SN-38 concentrations before and after PCI-IS correction. Moreover, only DXd concentrations after PCI-IS correction were significantly higher in patients with thrombocytopenia (p = 0.037).

SIGNIFICANCE

This approach effectively addressed the issue of unavailability of SIL-IS for novel ADC payloads and provided more accurate quantification, potentially yielding more robust statistical outcomes for understanding the exposure-toxicity relationship in ADCs. It is anticipated that this PCI-IS strategy may be extrapolated to quantify payloads and derivatives in diverse ADCs, thereby providing invaluable insights into drug toxicity and fortifying patient safety in ADC usage.

Population Pharmacokinetics of Sacituzumab Govitecan in Patients with Metastatic Triple-Negative Breast Cancer and Other Solid Tumors

BACKGROUND AND OBJECTIVE

Sacituzumab govitecan (SG) is an antibody-drug conjugate composed of an antibody with affinity for Trop-2 coupled to SN-38 via hydrolyzable linker. SG is approved for patients with metastatic triple-negative breast cancer (mTNBC) who have received two or more prior chemotherapies (at least one in a metastatic setting) and for patients with pretreated hormone receptor positive (HR+)/human epidermal growth factor receptor 2 negative (HER2-) metastatic breast cancer.

METHODS

In these analyses, the pharmacokinetics of SG, free SN-38, and total antibody (tAB) were characterized using data from 529 patients with mTNBC or other solid tumors across two large clinical trials (NCT01631552; ASCENT, NCT02574455). Three population pharmacokinetic models were constructed using non-linear mixed-effects modeling; clinically relevant covariates were evaluated to assess their impact on exposure. Models for SG and tAB were developed independently whereas free SN-38 was sequentially generated via a first-order release process from SG.

RESULTS

Pharmacokinetics of the three analytes were each described by a two-compartment model with estimated body weight-based scaling exponents for clearance and volume. Typical parameter estimates for clearance and steady-state volume of distribution were 0.133 L/h and 3.68 L for SG and 0.0164 L/h and 4.26 L for tAB, respectively. Mild-to-moderate renal impairment, mild hepatic impairment, age, sex, baseline albumin level, tumor type, UGT1A1 genotype, or Trop-2 expression did not have a clinically relevant impact on exposure for any of the three analytes.

CONCLUSIONS

These analyses support the approved SG dosing regimen of 10 mg/kg as intravenous infusion on days 1 and 8 of 21-day cycles and did not identify a need for dose adjustment based on evaluated covariates or disease characteristics.

The Safety and Efficacy of the Combination of Sacituzumab Govitecan and Palliative Radiotherapy-A Retrospective Multi-Center Cohort Study

Sacituzumab govitecan (SG) is a new treatment option for patients with metastatic triple-negative and hormone receptor-positive, HER2-negative breast cancer. This antibody-drug conjugate is currently approved as monotherapy. Palliative radiotherapy is frequently used to treat symptomatic metastases locally. Concurrent use of SG and irradiation was excluded in clinical trials of SG, and there are currently limited published data. We report here a systematic review, as well as a retrospective multi-center study of 17 patients with triple-negative breast cancer who received concurrent SG and radiotherapy. In these patients, concurrent use was found to be efficient, safe and well tolerated. There were no apparent differences in moderate or severe acute toxicity according to the timing of SG administration.

Sacituzumab Govitecan in Combination With Pembrolizumab for Patients With Metastatic Urothelial Cancer That Progressed After Platinum-Based Chemotherapy: TROPHY-U-01 Cohort 3

PURPOSE

Pembrolizumab is standard therapy for patients with metastatic urothelial cancer (mUC) who progress after first-line platinum-based chemotherapy; however, only approximately 21% of patients respond. Sacituzumab govitecan (SG) is a trophoblast cell surface antigen-2-directed antibody-drug conjugate with US Food and Drug Administration-accelerated approval to treat patients with locally advanced or mUC who previously received platinum-based chemotherapy and a checkpoint inhibitor (CPI). Here, we report the primary analysis of TROPHY-U-01 cohort 3.

METHODS

TROPHY-U-01 (ClinicalTrials.gov identifier: NCT03547973) is a multicohort, open-label phase II study. Patients were CPI-naïve and had mUC progression after platinum-based chemotherapy in the metastatic setting or ≤12 months in the (neo)adjuvant setting. Patients received 10 mg/kg of SG once on days 1 and 8 and 200 mg of pembrolizumab once on day 1 of 21-day cycles. The primary end point was objective response rate (ORR) per central review. Secondary end points included clinical benefit rate (CBR), duration of response (DOR) and progression-free survival (PFS) per central review, and safety.

RESULTS

Cohort 3 included 41 patients (median age 67 years; 83% male; 78% visceral metastases [29% liver]). With a median follow-up of 14.8 months, the ORR was 41% (95% CI, 26.3 to 57.9; 20% complete response rate), CBR was 46% (95% CI, 30.7 to 62.6), median DOR was 11.1 months (95% CI, 4.8 to not estimable [NE]), and median PFS was 5.3 months (95% CI, 3.4 to 10.2). The median overall survival was 12.7 months (range, 10.7-NE). Grade ≥3 treatment-related adverse events occurred in 61% of patients; most common were neutropenia (37%), leukopenia (20%), and diarrhea (20%).

CONCLUSION

SG plus pembrolizumab demonstrated a high response rate with an overall manageable toxicity profile in patients with mUC who progressed after platinum-based chemotherapy. No new safety signals were detected. These data support further evaluation of SG plus CPI in mUC.

Could a Long-Acting Prodrug of SN-38 be Efficacious in Sacituzumab Govitecan-Resistant Tumors?

We previously proposed that sacituzumab govitecan (SG, Trodelvy®) likely acts as a simple prodrug of systemic SN-38 as well as an antibody drug conjugate (ADC). In the present commentary, we assess whether a long-acting SN-38 prodrug, such as PLX038, might be efficacious in SG-resistant patients. We first describe possible mechanisms of action of SG, with new insights on pharmacokinetics and TROP2 receptor occupancy. We argue that SG is not an optimal conventional ADC and that the amount of systemic SN-38 spontaneously hydrolyzed from the ADC is so high it must have activity. Then, we describe the concept of time-over-target as related to the pharmacology of SG and PLX038 as SN-38 prodrugs. To be clear, we are not in any way suggesting that PLX038 or any SN-38 prodrug is superior to SG as an anticancer agent. Clearly, SG has the benefit over antigen-independent SN-38 prodrugs in that it targets cells with the TROP2 receptor. However, we surmise that PLX038 should be a more efficacious and less toxic prodrug of systemic SN-38 than SG. Finally, we suggest possible mechanisms of SG resistance and how PLX038 might perform in the context of each. Taken together, we argue that-contrary to many opinions-SG does not exclusively act as a conventional ADC, and propose that PLX038 may be efficacious in some settings of SG-resistance.

TROPION-Breast01: Datopotamab deruxtecan vs chemotherapy in pre-treated inoperable or metastatic HR+/HER2- breast cancer

Improving the prognosis for patients with metastatic HR+/HER2- breast cancer remains an unmet need. Patients with tumors that have progressed on endocrine therapy and/or are not eligible for endocrine therapy had limited treatment options beyond chemotherapy. Antibody-drug conjugates are a novel and promising treatment class in this setting. Datopotamab deruxtecan (Dato-DXd) consists of a TROP2-directed humanized IgG1 monoclonal antibody attached via a serum-stable cleavable linker to a topoisomerase I inhibitor payload. TROPION-Breast01 is an ongoing phase III study that is evaluating the efficacy and safety of Dato-DXd compared with investigator's choice of standard-of-care chemotherapy in patients with inoperable or metastatic HR+/HER2- breast cancer who have received one or two prior lines of systemic chemotherapy in the inoperable or metastatic setting. Clinical Trial Registration: NCT05104866 (ClinicalTrials.gov).

Sacituzumab govitecan plus platinum-based chemotherapy mediates significant antitumor effects in triple-negative breast, urinary bladder, and small-cell lung carcinomas

Sacituzumab govitecan (SG) is an antibody-drug conjugate composed of an anti-Trop-2-directed antibody conjugated with the topoisomerase I inhibitory drug, SN-38, via a proprietary hydrolysable linker. SG has received United States Food and Drug Administration (FDA) approval to treat metastatic triple-negative breast cancer (TNBC), unresectable locally advanced or metastatic hormone receptor (HR)-positive, human epidermal growth factor receptor 2 (HER2)-negative breast cancer, and accelerated approval for metastatic urothelial cancer. We investigated the utility of combining SG with platinum-based chemotherapeutics in TNBC, urinary bladder carcinoma (UBC), and small-cell lung carcinoma (SCLC). SG plus carboplatin or cisplatin produced additive growth-inhibitory effects in vitro that trended towards synergy. Immunoblot analysis of cell lysates suggests perturbation of the cell-cycle and a shift towards pro-apoptotic signaling evidenced by an increased Bax to Bcl-2 ratio and down-regulation of two anti-apoptotic proteins, Mcl-1 and survivin. Significant antitumor effects were observed with SG plus carboplatin in mice bearing TNBC or SCLC tumors compared to all controls (P < 0.0062 and P < 0.0017, respectively) and with SG plus cisplatin in UBC and SCLC tumor-bearing animals (P < 0.0362 and P < 0.0001, respectively). These combinations were well tolerated by the animals. Combining SG with platinum-based chemotherapeutics demonstrates the benefit in these indications and warrants further clinical investigation.

Breaking barriers in triple negative breast cancer (TNBC) - Unleashing the power of antibody-drug conjugates (ADCs)

Antibody-drug conjugates (ADCs) represent a novel class of molecules composed of a recombinant monoclonal antibody targeted to a specific cell surface antigen, conjugated to a cytotoxic agent through a cleavable or non-cleavable synthetic linker. The rationale behind the development of ADCs is to overcome the limitations of conventional chemotherapy, such as the narrow therapeutic window and the emergence of resistance mechanisms. ADCs had already revolutionized the treatment algorithm of HER2-positive breast cancer. Currently, emergent non-HER2 targeted ADCs are gaining momentum, with special focus on triple-negative disease therapeutic landscape. Sacituzumab govitecan (SG) is an ADC consisting of a humanized monoclonal antibody hRS7 targeting trophoblast cell surface antigen 2 (Trop2), linked to the topoisomerase I inhibitor SN-38 by a hydrolysable linker. It currently stands as the only non-HER2 targeted ADC that already received approval for the treatment of unresectable locally advanced or metastatic triple negative breast cancer (TNBC) in patients who had received two or more prior systemic therapies, with at least one for advanced disease. The purpose of these review is to analyze the available evidence regarding ADCs in TNBC, alongside with providing an overview on the ongoing and future research horizons in this field.

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.

Leveraging TROP2 Antibody-Drug Conjugates in Solid Tumors

Antibody-drug conjugates (ADCs) have become the cornerstone of effective therapeutics in solid and hematological malignancies by harnessing potent cytotoxic payloads with targeted tumoricidal delivery. Since the monumental shift occurred with HER2-targeted ADCs, the discovery of the TROP2 antigen has revolutionized the landscape of ADC development. Moving beyond the traditional ADC design, multiple novel ADCs have successfully shaped and improved survival outcomes in patients with various tumor histologies. Here we review and contrast the clinical impact of the well-known TROP2 ADCs currently in clinical use. We also shed light on upcoming investigational TROP2 ADCs showing promise with novel ADC platforms.

Targeted Therapies and Drug Resistance in Advanced Breast Cancer, Alternative Strategies and the Way beyond

"Targeted therapy" or "precision medicine" is a therapeutic strategy launched over two decades ago. It relies on drugs that inhibit key molecular mechanisms/pathways or genetic/epigenetic alterations that promote different cancer hallmarks. Many clinical trials, sponsored by multinational drug companies, have been carried out. During this time, research has increasingly uncovered the complexity of advanced breast cancer disease. Despite high expectations, patients have seen limited benefits from these clinical trials. Commonly, only a minority of trials are successful, and the few approved drugs are costly. The spread of this expensive therapeutic strategy has constrained the resources available for alternative research. Meanwhile, due to the high cost/benefit ratio, other therapeutic strategies have been proposed by researchers over time, though they are often not pursued due to a focus on precision medicine. Notable among these are drug repurposing and counteracting micrometastatic disease. The former provides an obvious answer to expensive targeted therapies, while the latter represents a new field to which efforts have recently been devoted, offering a "way beyond" the current research.

Phylogenetic conservation of Trop-2 across species-rodent and primate genomics model anti-Trop-2 therapy for pre-clinical benchmarks

A phylogenetic conservation analysis of Trop-2 across vertebrate species showed a high degree of sequence conservation, permitting to explore multiple models as pre-clinical benchmarks. Sequence divergence and incomplete conservation of expression patterns were observed in mouse and rat. Primate Trop-2 sequences were found to be 95%-100% identical to the human sequence. Comparative three-dimension primate Trop-2 structures were obtained with AlphaFold and homology modeling. This revealed high structure conservation of Trop-2 (0.66 ProMod3 GMQE, 0.80-0.86 ± 0.05 QMEANDisCo scores), with conservative amino acid changes at variant sites. Primate TACSTD2/TROP2 cDNAs were cloned and transfectants for individual ORF were shown to be efficiently recognized by humanized anti-Trop-2 monoclonal antibodies (Hu2G10, Hu2EF). Immunohistochemistry analysis of Macaca mulatta (rhesus monkey) tissues showed Trop-2 expression patterns that closely followed those in human tissues. This led us to test Trop-2 targeting in vivo in Macaca fascicularis (cynomolgus monkey). Intravenously injected Hu2G10 and Hu2EF were well tolerated from 5 to 10 mg/kg. Neither neurological, respiratory, digestive, urinary symptoms, nor biochemical or hematological toxicities were detected during 28-day observation. Blood serum pharmacokinetic (PK) studies were conducted utilizing anti-idiotypic antibodies in capture-ELISA assays. Hu2G10 (t1/2 = 6.5 days) and Hu2EF (t1/2 = 5.5 days) were stable in plasma, and were detectable in the circulation up to 3 weeks after the infusion. These findings validate primates as reliable models for Hu2G10 and Hu2EF toxicity and PK, and support the use of these antibodies as next-generation anti-Trop-2 immunotherapy tools.

Pharmacokinetics and pharmacodynamics of antibody-drug conjugates for the treatment of patients with breast cancer

INTRODUCTION

Currently three antibody-drug-conjugates (ADC) are approved by the European Medicines Agency (EMA) for treatment of breast cancer (BC) patient: trastuzumab-emtansine, trastuzumab-deruxtecan and sacituzumab-govitecan. ADC are composed of a monoclonal antibody (mAb) targeting a specific antigen, a cytotoxic payload and a linker. Pharmacokinetics (PK) and pharmacodynamics (PD) distinguish ADC from conventional chemotherapy and must be understood by clinicians.

AREAS COVERED

Our review delineates the PK/PD profiles of ADC approved for the treatment of BC with insight for future development. This is an expert opinion literature review based on the EMA's Assessment Reports, enriched by a comprehensive literature search performed on Medline in August 2023.

EXPERT OPINION

All three ADC distributions are described by a two-compartment structure: tissue and serum. Payload concentration peak is immediate but remains at low concentration. The distribution varied for all ADC only with body weight. mAb will be metabolised firstly by the saturable complex formation of ADC/Tumour-Receptor and secondly by binding of FcgRs in immune cells. They are all excreted in the bile and faeces with minimal urine elimination. Dose adjustments, apart from weight, are not recommended. Novel ADC are composed of cleavable linkers with various targets/payloads with the same PK/PD properties, but novel structures of ADC are in development.

Sacituzumab Govitecan as a Second-Line Treatment in Relapsed/Refractory Metastatic Triple-Negative Breast Cancer Patients: A Systematic Review and Meta-analysis

BACKGROUND

Chemotherapy, the only treatment option for metastatic triple-negative breast cancer (mTNBC), showed decreased survival rates. Trophoblast cell surface antigen-2 (Trop-2) could be a possible target for antibody-drug conjugates (ADCs).

OBJECTIVE

Sacituzumab govitecan (SG), an anti-Trop-2 ADC for pretreating relapsed/refractory mTNBC patients, was studied to know the efficacy and safety profile of the drug in mTNBC.

METHODS

The present review searched MEDLINE (via PubMed), WHO Clinical Trial Registry, Clinical Trials.gov, and Cochrane Central Register of Controlled Trials until December 25, 2022. The studies searched comprised randomized trials and observational studies (retrospective [case-control, cross-sectional] and prospective [cohort designs]). Efficacy assessment was performed in terms of complete response (CR), partial response (PR), objective response rate (ORR), stable disease (SD), progressive disease (PD), and clinical benefit rate (CBR), and safety in terms of adverse events.

RESULTS

The overall random-effects pooled prevalence of CR was 4.9 (95% CI: 3.2-7.1), PR was 35.6 (95% CI: 31.5-39.9), ORR was 6.8 (95% CI: 5.9-7.8), SD was 8.0 (95% CI: 6.7-9.4), PD was 5.1 (95% CI: 4.1-6.3), and CBR was 13.4 (95% CI: 11.8-15.1). Adverse events associated with the drug were neutropenia, fatigue, anemia, nausea, and others.

CONCLUSION AND RELEVANCE

This is the first meta-analysis conducted in relapsed/refractory mTNBC patients and found that SG is efficacious but associated with some adverse effects that are related to exposure to the drug. The application of these results will allow clinicians to use SG in the management of patients with mTNBC.

Introduction of Carbonyl Groups into Antibodies

Antibodies and their derivatives (scFv, Fabs, etc.) represent a unique class of biomolecules that combine selectivity with the ability to target drug delivery. Currently, one of the most promising endeavors in this field is the development of molecular diagnostic tools and antibody-based therapeutic agents, including antibody-drug conjugates (ADCs). To meet this challenge, it is imperative to advance methods for modifying antibodies. A particularly promising strategy involves the introduction of carbonyl groups into the antibody that are amenable to further modification by biorthogonal reactions, namely aliphatic, aromatic, and α-oxo aldehydes, as well as aliphatic and aryl-alkyl ketones. In this review, we summarize the preparation methods and applications of site-specific antibody conjugates that are synthesized using this approach.

Post-marketing safety surveillance of sacituzumab govitecan: an observational, pharmacovigilance study leveraging FAERS database

Background and objective: Sacituzumab govitecan (SG), the first antibody-drug conjugate targeting human trophoblast cell-surface antigen 2 (Trop-2), has been approved by the Food and Drug Administration (FDA) for the treatment of advanced or metastatic breast cancer and urothelial cancer. However, there is currently a dearth of information regarding the safety profiles of SG in a large sample cohort. The objective of the present study is to investigate SG-related adverse events (AEs) in real-world settings leveraging the FDA Adverse Event Reporting System (FAERS) database to guide the safety management of clinical medication. Methods: The FAERS database was retrospectively queried to extract reports associated with SG from April 2020 to March 2023. To identify and evaluate potential AEs in patients receiving SG, various disproportionality analyses such as reporting odds ratio (ROR), the proportional reporting ratio (PRR), the Bayesian confidence propagation neural network (BCPNN), and the multi-item gamma Poisson shrinker (MGPS) were employed. Results: Overall, 2069 reports of SG as the "primary suspect" were identified. Noteworthy, SG was significantly associated with an increased risk of blood lymphatic system disorders (ROR, 7.18; 95% CI, 6.58-7.84) and hepatobiliary disorders (ROR, 2.68; 95% CI, 2.17-3.30) at the System Organ Class (SOC) level. Meanwhile, 61 significant disproportionality preferred terms (PTs) simultaneously complied with all four algorithms were adopted. Therein, anemia, thrombocytopenia, neutropenia, leukopenia, diarrhea, asthenia, alopecia, and electrolyte imbalance were consistent with the common AEs described in the clinical trials and specification of SG. Furthermore, unexpected significant AEs include colitis (ROR, 12.09; 95% CI, 9.1-16.08), heart rate increased (ROR, 5.11; 95% CI, 3.84-6.79), sepsis (ROR, 4.77; 95% CI, 3.59-6.34), cholestasis (ROR, 6.28; 95% CI, 3.48-11.36), blood bilirubin increased (ROR, 4.65; 95% CI, 2.42-8.94) and meningitis (ROR, 7.23; 95% CI, 2.71-19.29) were also be detected. The median time to onset of SG-related AEs was 14 [interquartile range (IQR), 7-52] days, with the majority occurring within the initial month of SG treatment. Conclusion: Our study validates the commonly known AEs and also found some potentially emerging safety issues related to SG in real-world clinical practice, which could provide valuable vigilance evidence for clinicians and pharmacists to manage the safety issues of SG.

TROP2-directed nanobody-drug conjugate elicited potent antitumor effect in pancreatic cancer

BACKGROUND

Pancreatic cancer is a highly aggressive malignancy with limited treatment options and a poor prognosis. Trophoblast cell surface antigen 2 (TROP2), a cell surface antigen overexpressed in the tumors of more than half of pancreatic cancer patients, has been identified as a potential target for antibody-drug conjugates (ADCs). Almost all reported TROP2-targeted ADCs are of the IgG type and have been poorly studied in pancreatic cancer. Here, we aimed to develop a novel nanobody-drug conjugate (NDC) targeting TROP2 for the treatment of pancreatic cancer.

RESULTS

In this study, we developed a novel TROP2-targeted NDC, HuNbTROP2-HSA-MMAE, for the treatment of TROP2-positive pancreatic cancer. HuNbTROP2-HSA-MMAE is characterized by the use of nanobodies against TROP2 and human serum albumin (HSA) and has a drug-antibody ratio of 1. HuNbTROP2-HSA-MMAE exhibited specific binding to TROP2 and was internalized into tumor cells with high endocytosis efficiency within 5 h, followed by intracellular translocation to lysosomes and release of MMAE to induce cell apoptosis in TROP2-positive pancreatic cancer cells through the caspase-3/9 pathway. In a xenograft model of pancreatic cancer, doses of 0.2 mg/kg and 1 mg/kg HuNbTROP2-HSA-MMAE demonstrated significant antitumor effects, and a dose of 5 mg/kg even eradicated the tumor.

CONCLUSION

HuNbTROP2-HSA-MMAE has desirable affinity, internalization efficiency and antitumor activity. It holds significant promise as a potential therapeutic option for the treatment of TROP2-positive pancreatic cancer.

Navigating the Rapidly Evolving Advanced Urothelial Carcinoma Treatment Landscape: Insights from Italian Experts

PURPOSE OF REVIEW

To discuss recent advances in the treatment of advanced urothelial carcinoma (UC) and how best to incorporate new therapies into clinical practice.

RECENT FINDINGS

There have been several recent practice-changing phase 2 and 3 trials of immune checkpoint inhibitors (ICIs), antibody-drug conjugates (ADCs), and targeted agents in advanced UC. Based on data from these trials, ICIs can be used as first-line maintenance therapy in patients who do not progress on platinum-based chemotherapy, second-line therapy for those with progression, and first-line therapy in cisplatin-ineligible patients with PD-L1 expression; ADCs and targeted agents provide later-line treatment options. Despite substantial progress in the treatment of advanced UC, there are still many uncertainties, including the optimal treatment sequence for novel agents, and reliable predictive biomarkers to aid in treatment selection. There is also an unmet need for effective treatment options in patients unfit for any platinum-based chemotherapy.

Use of Payload Binding Selectivity Enhancers to Improve Therapeutic Index of Maytansinoid-Antibody-Drug Conjugates

Systemic exposure to released cytotoxic payload contributes to the dose-limiting off-target toxicities of anticancer antibody-drug conjugates (ADC). In this work, we present an "inverse targeting" strategy to optimize the therapeutic selectivity of maytansinoid-conjugated ADCs. Several anti-maytansinoid sdAbs were generated via phage-display technology with binding IC50 values between 10 and 60 nmol/L. Co-incubation of DM4 with the anti-maytansinoid sdAbs shifted the IC50 value of DM4 up to 250-fold. Tolerability and efficacy of 7E7-DM4 ADC, an anti-CD123 DM4-conjugated ADC, were assessed in healthy and in tumor-bearing mice, with and without co-administration of an anti-DM4 sdAb. Co-administration with anti-DM4 sdAb reduced 7E7-DM4-induced weight loss, where the mean values of percentage weight loss at nadir for mice receiving ADC+saline and ADC+sdAb were 7.9% ± 3% and 3.8% ± 1.3% (P < 0.05). In tumor-bearing mice, co-administration of the anti-maytansinoid sdAb did not negatively affect the efficacy of 7E7-DM4 on tumor growth or survival following dosing of the ADC at 1 mg/kg (P = 0.49) or at 10 mg/kg (P = 0.9). Administration of 7E7-DM4 at 100 mg/kg led to dramatic weight loss, with 80% of treated mice succumbing to toxicity before the appearance of mortality relating to tumor growth in control mice. However, all mice receiving co-dosing of 100 mg/kg 7E7-DM4 with anti-DM4 sdAb were able to tolerate the treatment, which enabled reduction in tumor volume to undetectable levels and to dramatic improvements in survival. In summary, we have demonstrated the utility and feasibility of the application of anti-payload antibody fragments for inverse targeting to improve the selectivity and efficacy of anticancer ADC therapy.

A pharmacovigilance study on drug-induced liver injury associated with antibody-drug conjugates (ADCs) based on the food and drug administration adverse event reporting system

BACKGROUND

This study aimed to assess the association between drug-induced liver injury (DILI) and antibody-drug conjugates (ADCs) by comprehensively evaluating spontaneous reports submitted to the Food and Drug Administration Adverse Event Reporting System (FAERS) database from 2004Q1 to 2022Q3.

RESEARCH DESIGN AND METHODS

All DILI cases with ADCs as primary suspected drugs were extracted from the FAERS database from 2004Q1 to 2022Q3 using OpenVigil 2.1. The reporting odds ratio (ROR) and the proportional reporting ratio (PRR) for reporting the association between different drugs and DILI risk were calculated.

RESULTS

A total of 504 DILI cases were attributed to ADCs during the study period. Patients with ADCs-related DILI (n = 504) had a mean age of 56.2 ± 18.4 years, with 167 cases not reporting patients' age. Females and males comprised 42.5% and 44.0% of the cases, respectively, while there was no information on gender in 13.5% of the cases. The DILI signals were detected in trastuzumab emtansine, enfortumab vedotin, brentuximab vedotin, polatuzumab vedotin, gemtuzumab ozogamicin, inotuzumab ozogamicin, and trastuzumab deruxtecan.

CONCLUSIONS

The FAERS data mining suggested an association between DILI and some ADCs. Further studies are warranted to unraveling the underlying mechanisms and taking preventive measures for ADCs-related DILI.

Assessing real-world safety concerns of Sacituzumab govitecan: a disproportionality analysis using spontaneous reports in the FDA adverse event reporting system

Aim

The aim of this study was to identify potential safety concerns associated with Sacituzumab Govitecan (SG), an antibody-drug conjugate targeting trophoblastic cell-surface antigen-2, by analyzing real-world safety data from the largest publicly available worldwide pharmacovigilance database.

Methods

All data obtained from the FDA Adverse Event Reporting System (FAERS) database from the second quarter of 2020 to the fourth quarter of 2022 underwent disproportionality analysis and Bayesian analysis to detect and assess the adverse event signals of SG, considering statistical significance when the lower limit of the 95% CI >1, based on at least 3 reports.

Results

Total of 1072 cases were included. The main safety signals were blood and lymphatic system disorders [ROR(95CI)=7.23 (6.43-8.14)], gastrointestinal disorders [ROR(95CI)=2.01 (1.81-2.22)], and relative infection adverse events, such as neutropenic sepsis [ROR(95CI)=46.02 (27.15-77.99)] and neutropenic colitis [ROR(95CI)=188.02 (120.09-294.37)]. We also noted unexpected serious safety signals, including large intestine perforation [ROR(95CI)=10.77 (3.47-33.45)] and hepatic failure [ROR(95CI)=3.87 (1.45-10.31)], as well as a high signal for pneumonitis [ROR(95CI)=9.93 (5.75-17.12)]. Additionally, age sub-group analysis revealed that geriatric patients (>65 years old) were at an increased risk of neutropenic colitis [ROR(95CI)=282.05 (116.36-683.66)], neutropenic sepsis [ROR(95CI)=101.11 (41.83-244.43)], acute kidney injury [ROR(95CI)=3.29 (1.36-7.94)], and atrial fibrillation [ROR(95CI)=6.91 (2.86-16.69)].

Conclusion

This study provides crucial real-world safety data on SG, complementing existing clinical trial information. Practitioners should identify contributing factors, employ monitoring and intervention strategies, and focus on adverse events like neutropenic sepsis, large intestine perforation, and hepatic failure. Further prospective studies are needed to address these safety concerns for a comprehensive understanding and effective management of associated risks.

Antibody-drug conjugates for urothelial carcinoma

The standard of care for advanced urothelial carcinoma includes platinum chemotherapy and immunotherapy. Antibody-drug conjugates (ADCs), originally developed for hematologic malignancies, involve potent cytotoxic agents linked to antibodies that recognize tumor-specific antigens; this rational drug design allows for more on-target efficacy, while mitigating systemic toxicity. Herein, we review the emerging landscape of ADCs in urothelial carcinoma. The anti-Nectin-4 ADC enfortumab vedotin has demonstrated efficacy in prospective studies in patients with advanced urothelial carcinoma in several settings either alone or in combination with pembrolizumab. The anti-Trop-2 ADC sacituzumab govitecan has also shown efficacy in single-armed studies. Both conjugates have full or accelerated approval from the Food and Drug Administration. Common adverse events include rash and neuropathy for enfortumab vedotin and myelosuppression and diarrhea for sacituzumab govitecan. Several anti-human epidermal growth factor receptor 2 ADCs are in clinical trials, and in localized bladder cancer, the anti-epithelial cell adhesion molecule ADC oportuzumab monatox is being studied in patients refractory to intravesical bacillus calmette-guerin therapy. Antibody-drug conjugates for urothelial carcinoma are approved and emerging as therapies for patients with advanced urothelial carcinoma, filling a prior void for treatment of progressive disease. Ongoing studies are also evaluating these agents in the neoadjuvant and adjuvant settings.

Targeting Replication Stress and Chemotherapy Resistance with a Combination of Sacituzumab Govitecan and Berzosertib: A Phase I Clinical Trial

PURPOSE

Despite promising preclinical studies, toxicities have precluded combinations of chemotherapy and DNA damage response (DDR) inhibitors. We hypothesized that tumor-targeted chemotherapy delivery might enable clinical translation of such combinations.

PATIENTS AND METHODS

In a phase I trial, we combined sacituzumab govitecan, antibody-drug conjugate (ADC) that delivers topoisomerase-1 inhibitor SN-38 to tumors expressing Trop-2, with ataxia telangiectasia and Rad3-related (ATR) inhibitor berzosertib. Twelve patients were enrolled across three dose levels.

RESULTS

Treatment was well tolerated, with improved safety over conventional chemotherapy-based combinations, allowing escalation to the highest dose. No dose-limiting toxicities or clinically relevant ≥grade 4 adverse events occurred. Tumor regressions were observed in 2 patients with neuroendocrine prostate cancer, and a patient with small cell lung cancer transformed from EGFR-mutant non-small cell lung cancer.

CONCLUSIONS

ADC-based delivery of cytotoxic payloads represents a new paradigm to increase efficacy of DDR inhibitors. See related commentary by Berg and Choudhury, p. 3557.

Narciclasine, a novel topoisomerase I inhibitor, exhibited potent anti-cancer activity against cancer cells

DNA topoisomerases are essential nuclear enzymes in correcting topological DNA errors and maintaining DNA integrity. Topoisomerase inhibitors are a significant class of cancer chemotherapeutics with a definite curative effect. Natural products are a rich source of lead compounds for drug discovery, including anti-tumor drugs. In this study, we found that narciclasine (NCS), an amaryllidaceae alkaloid, is a novel inhibitor of topoisomerase I (topo I). Our data demonstrated that NCS inhibited topo I activity and reversed its unwinding effect on p-HOT DNA substrate. However, it had no obvious effect on topo II activity. The molecular mechanism of NCS inhibited topo I showed that NCS did not stabilize topo-DNA covalent complexes in cells, indicating that NCS is not a topo I poison. A blind docking result showed that NCS could bind to topo I, suggesting that NCS might be a topo I suppressor. Additionally, NCS exhibited a potent anti-proliferation effect in various cancer cells. NCS arrested the cell cycle at G2/M phase and induced cell apoptosis. Our study reveals the antitumor mechanisms of NCS and provides a good foundation for the development of anti-cancer drugs based on topo I inhibition.

Antibody-drug conjugates (ADCs) targeting TROP-2 in lung cancer

INTRODUCTION

The advent of antibody-drug conjugates (ADCs) represents a renewed strategy in the era of precision oncology. Several epithelial tumors harbor overexpression of the trophoblast cell-surface antigen 2 (TROP-2), which represents a predictor of poor prognosis and a promising target for anticancer therapy.

AREAS COVERED

In this review, we aim to collect the available preclinical and clinical data regarding anti-TROP-2 ADCs in lung cancer obtained through extensive literature research and screening of the available abstract/posters presented at recent meetings.

EXPERT OPINION

Anti-TROP-2 ADCs represent an innovative upcoming weapon against both non-small cell lung cancer and small cell lung cancer subtypes, pending the results of several ongoing trials. The proper combination and placement of this agent throughout the lung cancer treatment pathway, the identification of potentially predictive biomarkers of benefit, as well as the optimal management and impact of peculiar toxicity (i.e. interstitial lung disease) are the next questions to be answered.

Managing adverse events of sacituzumab govitecan

INTRODUCTION

The development of antibody-drug conjugates (ADCs) have revolutionized treatment for breast cancer. Sacituzumab govitecan (SG), a Trop2-targeted ADC, has demonstrated remarkable efficacy in triple-negative breast cancer (TNBC) and hormone receptor-positive metastatic breast cancer.

AREAS COVERED

We summarize the evidence for SG use in the treatment of metastatic breast cancer, discuss the toxicity profile, and present strategies to manage adverse events.

EXPERT OPINION

Hematologic toxicities are frequently observed with SG therapy. Neutropenia, reported in up to 72% of cases, often requires dose reductions or delays. Granulocyte colony-stimulating factor can be helpful in managing and preventing this toxicity. Anemia is another common toxicity and patients may require transfusions of packed red blood cells. Gastrointestinal toxicities are also common. A tailored regimen of prophylactic antiemetics (2-3 agents) should be initiated before SG infusion. For diarrhea, infectious workup should be considered on a case-by-case basis; patients should start loperamide and fluid/electrolyte replacement if necessary. Severe diarrhea associated with cholinergic syndrome should prompt the administration of atropine. Fatigue occurs in approximately half of the patients receiving SG, and <50% of patients experience complete alopecia during treatment. The approval of SG has significantly improved treatment outcomes; however, effective management of the toxicities is critical to optimize patient care and treatment adherence.

TROP-2 directed antibody-drug conjugates (ADCs): The revolution of smart drug delivery in advanced non-small cell lung cancer (NSCLC)

BACKGROUND

Antibody drug conjugates (ADCs) represent a revolutionary drug class in cancer therapy, combining the precision of targeted therapy with the cytotoxic effects of chemotherapy. Promising activity of novel ADCs, namely Trastuzumab Deruxtecan and Patritumab Deruxtecan, has been observed in hard-to treat molecular subtypes, such as HER2-positive and heavily pretreated EGFR-mutant Non-Small Cell Lung Cancer (NSCLC). However, therapeutic advances are expected in certain subgroups of lung cancer patients, including non-oncogene-addicted NSCLC after failure of current standard of care (e.g., immunotherapy with or without chemotherapy, chemo-antiangiogenic treatment). Trophoblastic Cell Surface Antigen 2 (TROP-2) is a surface transmembrane glycoprotein member of the epithelial cell adhesion molecule (EpCAM) family. TROP-2 represents a promising therapeutic target in refractory non-oncogene-addicted NSCLC.

METHODOLOGY

We performed a systematic literature search of the clinical trials about TROP-2 directed ADCs in NSCLC referenced in the pubmed.gov database, Cochrane Library database and clinicaltrial.gov database.

RESULTS

First-in-humans ADCs targeting TROP-2, namely Sacituzumab Govitecan (SN-38) and Datopotamab Deruxtecan (Dxd), yielded promising activity signals in NSCLC with a manageable safety profile. Most common grade ≥ 3 adverse events (AEs) of Sacituzumab Govitecan included neutropenia (28 %), diarrhea (7 %), nausea (7 %), fatigue (6 %), and febrile neutropenia (4 %). Nausea and stomatitis were the most common all grade AEs with Datopotamab Deruxtecan; dyspnea, amylase increase, hyperglycemia and lymphopenia were reported as grade ≥ 3 AEs in less than 12 % of patients.

CONCLUSION

As more effective strategies are needed for patients with refractory non-oncogene-addicted NSCLC, the design of novel clinical trials with ADCs targeting TROP-2 is encouraged as both a monotherapy or combination strategy with existing agents (e.g., monoclonal antibodies targeting immune checkpoint inhibitors or chemotherapy).

The Chemistry of Creating Chemically Programmed Antibodies (cPAbs): Site-Specific Bioconjugation of Small Molecules

Small-molecule drugs have been employed for years as therapeutics in the pharmaceutical industry. However, small-molecule drugs typically have short in vivo half-lives which is one of the largest impediments to the success of many potentially valuable pharmacologically active small molecules. The undesirable pharmacokinetics and pharmacology associated with some small molecules have led to the development of a new class of bioconjugates known as chemically programmed antibodies (cPAbs). cPAbs are bioconjugates in which antibodies are used to augment small molecules with effector functions and prolonged pharmacokinetic profiles, where the pharmacophore of the small molecule is harnessed for target binding and therefore biological targeting. Many different small molecules can be conjugated to large proteins such as full monoclonal antibodies (IgG), fragment crystallizable regions (Fc), or fragment antigen binding regions (Fab). In order to successfully and site-specifically conjugate small molecules to any class of antibodies (IgG, Fc, or Fab), the molecules must be derivatized with a functional group for ease of conjugation without altering the pharmacology of the small molecules. In this Review, we summarize the different synthetic or biological methods that have been employed to produce cPAbs. These unique chemistries have potential to be applied to other fields of antibody modification such as antibody drug conjugates, radioimmunoconjugates, and fluorophore-tagged antibodies.

Mechanisms of ADC Toxicity and Strategies to Increase ADC Tolerability

Anti-cancer antibody-drug conjugates (ADCs) aim to expand the therapeutic index of traditional chemotherapy by employing the targeting specificity of monoclonal antibodies (mAbs) to increase the efficiency of the delivery of potent cytotoxic agents to malignant cells. In the past three years, the number of ADCs approved by the Food and Drug Administration (FDA) has tripled. Although several ADCs have demonstrated sufficient efficacy and safety to warrant FDA approval, the clinical use of all ADCs leads to substantial toxicity in treated patients, and many ADCs have failed during clinical development due to their unacceptable toxicity profiles. Analysis of the clinical data has demonstrated that dose-limiting toxicities (DLTs) are often shared by different ADCs that deliver the same cytotoxic payload, independent of the antigen that is targeted and/or the type of cancer that is treated. DLTs are commonly associated with cells and tissues that do not express the targeted antigen (i.e., off-target toxicity), and often limit ADC dosage to levels below those required for optimal anti-cancer effects. In this manuscript, we review the fundamental mechanisms contributing to ADC toxicity, we summarize common ADC treatment-related adverse events, and we discuss several approaches to mitigating ADC toxicity.

The new era of prostate-specific membrane antigen-directed immunotherapies and beyond in advanced prostate cancer: a review

The lack of success in prostate cancer from immune checkpoint inhibitors, which is likely multifactorial, has led to the development and investigation of a number of other novel immunotherapeutic techniques, including antibody-drug conjugates, T-cell redirected bispecific therapies, cancer vaccines and chimeric antigen receptor T-cell therapies. Prostate-specific membrane antigen (PSMA) is a tumour-associated antigen (TAA) that is highly expressed in metastatic prostate cancer and has been validated as an effective target for radionuclide treatment. But while PSMA has thus far been the 'front runner' target for these novel immunotherapeutic techniques, it may not be the ideal target for immunotherapy and there are other potential targetable TAAs that will require further exploration. This review will focus on these various PSMA-directed therapies, as well as other potential targets for immunotherapy beyond PSMA.

The diverse landscape of dermatologic toxicities of non-immune checkpoint inhibitor monoclonal antibody-based cancer therapy

BACKGROUND

Since their first approval 25 years ago, monoclonal antibodies (mAbs) have become important targeted cancer therapeutics. However, dermatologic toxicities associated with non-immune checkpoint inhibitor (non-ICI) mAbs may complicate the course of cancer treatment. Data on the incidence and types of these reactions are limited.

METHODS

A comprehensive review was conducted on dermatologic toxicities associated with different classes of non-ICI mAbs approved for treatment of solid tumors and hematologic malignancies. The review included prospective Phase 1, 2, and 3 clinical trials; retrospective literature reviews; systematic reviews/meta-analyses; and case series/reports.

RESULTS

Dermatologic toxicities were associated with several types of non-ICI mAbs. Inflammatory reactions were the most common dermatologic toxicities, manifesting as maculopapular, urticarial, papulopustular/acneiform, and lichenoid/interface cutaneous adverse events (cAEs) with non-ICI mAbs. Immunobullous reactions were rare and a subset of non-ICI mAbs were associated with the development of vitiligo cAEs.

CONCLUSION

Dermatologic toxicities of non-ICI mAbs are diverse and mostly limited to inflammatory reactions. Awareness of the spectrum of the histopathologic patterns of cAE from non-ICI mAbs therapy is critical in the era of oncodermatology and oncodermatopathology.

Preclinical profiles of SKB264, a novel anti-TROP2 antibody conjugated to topoisomerase inhibitor, demonstrated promising antitumor efficacy compared to IMMU-132

Purpose

The aim of this study was to improve the intratumoral accumulation of an antibody-drug conjugate (ADC) and minimize its off-target toxicity, SKB264, a novel anti-trophoblast antigen 2 (TROP2) ADC that was developed using 2-methylsulfonyl pyrimidine as the linker to conjugate its payload (KL610023), a belotecan-derivative topoisomerase I inhibitor. The preclinical pharmacologic profiles of SKB264 were assessed in this study.

Methods

The in vitro and in vivo pharmacologic profiles of SKB264, including efficacy, pharmacokinetics-pharmacodynamics (PK-PD), safety, and tissue distribution, were investigated using TROP2-positive cell lines, cell-derived xenograft (CDX), patient-derived xenograft (PDX) models, and cynomolgus monkeys. Moreover, some profiles were compared with IMMU-132.

Results

In vitro, SKB264 and SKB264 monoclonal antibody (mAb) had similar internalization abilities and binding affinities to TROP2. After cellular internalization, KL610023 was released and inhibited tumor cell survival. In vivo, SKB264 significantly inhibited tumor growth in a dose-dependent manner in both CDX and PDX models. After SKB264 administration, the serum or plasma concentration/exposure of SKB264 (conjugated ADC, number of payload units ≥1), total antibody (Tab, unconjugated and conjugated mAb regardless of the number of the payload units), and KL610023 in cynomolgus monkeys increased proportionally with increasing dosage from 1 to 10 mg/kg. The linker stability of SKB264 was significantly enhanced as shown by prolonged payload half-life in vivo (SKB264 vs. IMMU-132, 56.3 h vs. 15.5 h). At the same dose, SKB264's exposure in tumor tissue was 4.6-fold higher than that of IMMU-132.

Conclusions

Compared with IMMU-132, the longer half-life of SKB264 had a stronger targeting effect and better antitumor activity, suggesting the better therapeutic potential of SKB264 for treating TROP2-positive tumors.

Targeted Therapy for Locally Advanced or Metastatic Urothelial Cancer (mUC): Therapeutic Potential of Sacituzumab Govitecan

Urothelial carcinoma is the second most frequent genitourinary malignancy. Despite the poor prognosis, new treatment options have emerged and have expanded the therapeutic landscape for the disease. Although major improvements have been achieved, many patients experience rapid disease progression and low responses in subsequent lines of therapy. Sacituzumab govitecan is an ADC that targets Trop-2, which is highly expressed in urothelial cancers. Promising results in early clinical trials have led to further drug development which confirmed encouraging efficacy. Sacituzumab govitecan has been given accelerated approval in 2021 for patients with locally advanced and metastatic urothelial cancer who previously received a platinum containing chemotherapy and either a programmed death receptor-1 or programmed death ligand inhibitor. The results are promising, with encouraging efficacy and safety, however responses are not universal. There is a growing comprehension of mechanisms of resistance and predictive biomarkers that are crucial to improving outcomes. In this review, we summarize the current knowledge on antibody-drug conjugates and the clinical findings that led to the approval of Sacituzumab govitecan and discuss the therapeutic potential of new combinations, mechanisms of resistance and predictive biomarkers.

Trop-2 as a Therapeutic Target in Breast Cancer

The emergence of Trop-2 as a therapeutic target has given rise to new treatment paradigms for the treatment of patients with advanced and metastatic breast cancer. Trop-2 is most highly expressed in triple negative breast cancer (TNBC), but the receptor is found across all breast cancer subtypes. With sacituzumab govitecan, the first FDA-approved, Trop-2 inhibitor, providing a survival benefit in patients with both metastatic TNBC and hormone receptor positive breast cancer, additional Trop-2 directed therapies are under investigation. Ongoing studies of combination regimens with immunotherapy, PARP inhibitors, and other targeted agents aim to further harness the effect of Trop-2 inhibition. Current investigations are also underway in the neoadjuvant and adjuvant setting to evaluate the therapeutic benefit of Trop-2 inhibition in patients with early stage disease. This review highlights the significant impact the discovery Trop-2 has had on our patients with heavily pretreated breast cancer, for whom few treatment options exist, and the future direction of novel Trop-2 targeted therapies.

Targeted Therapies in Advanced and Metastatic Urothelial Carcinoma

This review describes the current landscape of targeted therapies in urothelial carcinoma. The standard of care for advanced urothelial carcinoma patients remains platinum-based combination chemotherapy followed by immunotherapy. However, median overall survival for these patients is still <1 year and there is an urgent need for alternative therapies. The advent of next-generation sequencing has allowed widespread comprehensive molecular characterization of urothelial tumors and, subsequently, the development of therapies targeting specific molecular pathways implicated in carcinogenesis such as FGFR inhibition, Nectin-4, Trop-2, and HER2 targeting. As these therapies are demonstrated to be effective in the second-line setting, they will be advanced in the treatment paradigm to localized and even non-muscle invasive disease.

Advances in Trop2-targeted therapy: Novel agents and opportunities beyond breast cancer

Trop2 is a transmembrane glycoprotein and calcium signal transducer with limited expression in normal human tissues. It is consistently overexpressed in a variety of malignant tumors and participates in several oncogenic signaling pathways that lead to tumor development, invasion, and metastasis. As a result, Trop2 has become an attractive therapeutic target in cancer treatment. The anti-Trop2 antibody-drug conjugate (Trodelvy™, sacituzumab govitecan) has been approved to treat metastatic triple-negative breast cancer. However, it is still unclear whether the success observed in Trop2-positive breast cancer could be replicated in other tumor types, owing to the differences in the expression levels and functions of Trop2 across cancer types. In this review, we summarize the recent progress on the structures and functions of Trop2 and highlight the potential diagnostic and therapeutic value of Trop2 beyond breast cancer. In addition, the promising novel Trop2-targeted agents in the clinic were discussed, which will likely alter the therapeutic landscape of Trop2-positive tumors in the future.

Antibody-drug conjugates targeting Trop-2: Clinical developments in early breast cancer therapy

Although breast cancer has a good prognosis compared with various cancers, metastatic breast cancer has an aggressive disease course and remains incurable. Therefore, treatment of early breast cancer to prevent recurrence and metastasis is crucial. Recently, the development of anti-cancer drugs, such as targeted agents and immuno-oncology, has been accelerating. Antibody-drug conjugates (ADCs) are also building a new paradigm. Particularly, ADCs targeting Trop-2 were approved for their efficacy in metastatic triple-negative breast cancer patients who received ≥2 prior systemic therapies and showed significant results in heavily pretreated hormone receptor-positive/HER2-negative breast cancer. In this brief review, we provide an overview of ongoing clinical trials of ADCs targeting Trop-2 in early breast cancer, specifically sacituzumab govitecan.

Precision Medicine in the Treatment of Locally Advanced or Metastatic Urothelial Cancer: New Molecular Targets and Pharmacological Therapies

Simple Summary

Therapeutic breakthroughs in urothelial carcinoma have been occurring rapidly over the past 10 years. However, the resistance and prognosis of this disease is always quite a difficult health challenge. Trying to understand the new therapeutic perspectives is a priority to try to bring in new drug models that can counteract the advancing prognosis and inauspicious diagnosis.

Abstract

Many variants of urothelial cancer present diagnostic challenges and carry clinical implications that influence prognosis and treatment decisions. The critical issues of treatment-resistant clones are a crucial barrier to care in individuals affected by urothelial carcinoma. Laying the foundations for the resistance evolution, a wide mutational heterogeneity characterizes urothelial carcinoma, noticeable also in patients affected by a early stage disease. In recent years the growing knowledge of the pathogenesis and molecular paths underlying the onset and progression of urothelial cancer are leading to the development of new therapies based on immune checkpoints. Chemotherapy and immunotherapy both operate selectively by shaping the developmental trajectory of urothelial carcinoma in the course of the illness. To date, a promising new therapeutic treatment is represented by antibody-drug conjugates, therapeutic tools that exploit the targeted ability of an antibody to administer cytotoxic drugs directly to the tumor. Indeed, nowadays in the clinical setting there are several treatments available for the treatment of locally advanced or metastatic urothelial cancer, from classic chemotherapeutics such as Gemcitabine, Cisplatin and Carboplatin, Paclitaxel and Docetaxel, to Programmed cell death protein 1 (PD-1) or Programmed death-ligand 1 (PD-L1) inhibitors such as Atezolizumab, Avelumab, Nivolumab, Pembrolizumab, up to anti-nectin 4 Enfortumab Vedotin and Sacituzumab govitecan, which binds Tumor-associated calcium signal transducer 2 (Trop-2) and activates as a topoisomerase inhibitor. The aim of this work is to describe the molecular mechanisms underlying the onset of the urothelial cancer and provide an overview of the immunotherapies that can be used in the clinical setting to counteract it, deepening the efficacy and safety results of the pivotal studies and the place in therapy of these treatments.

Antibody-drug conjugates targeting TROP-2: Clinical development in metastatic breast cancer

Antibody drug conjugates (ADCs) combine the potent cytotoxicity of chemotherapy with the antigen -specific targeted approach of antibodies into one single molecule. Trophoblast cell surface antigen 2 (TROP-2) is a transmembrane glycoprotein involved in calcium signal transduction and is expressed in multiple tumor types. TROP-2 expression is higher in HER2-negative breast tumors (HR+/HR-) and is associated with worse survival. Sacituzumab govitecan (SG) is a first-in-class TROP-2-directed ADC with an anti-TROP-2 antibody conjugated to SN-38, a topoisomerase inhibitor via a hydrolysable linker. This hydrolysable linker permits intracellular and extracellular release of the membrane permeable payload enabling the "bystander effect" contributing to the efficacy of this agent. There was significant improvement in progression free survival (PFS) and overall survival (OS) with SG versus chemotherapy in pretreated metastatic triple negative breast cancer (TNBC), resulting in regulatory approval. Common adverse events (AE) reported were neutropenia and diarrhea. SG also demonstrated clinical activity versus chemotherapy in a phase III trial of HR+/HER2-metastatic breast cancer (MBC) and is under evaluation in first-line metastatic and early stage TNBC as well. Datopotamab deruxtecan (Dato-DXd) is a TROP-2 ADC that differs from SG in that it has a cleavable tetrapeptide linker and a more potent topoisomerase inhibitor payload. This construct is highly stable in circulation with a longer half-life than SG, and undergoes cleavage in presence of intracellular lysosomal proteases. Dato-DXd demonstrated preliminary efficacy in unselected metastatic TNBC, with common AEs of low-grade nausea and stomatitis. Dato-DXd is being investigated in phase III studies in metastatic TNBC and HR+/HER2- MBC. These novel TROP-2 ADCs have the potential to deliver enhanced efficacy with reduced toxicity in MBC and possibly in early stage breast cancer (EBC).

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.

Antibody-drug conjugates: What drives their progress?

Antibody-drug conjugates (ADCs) are on the brink of widespread use for the targeted treatment of cancer. ADCs manage the toxicity of drugs with unacceptable narrow therapeutic windows by guiding highly toxic compounds to the target cells, thereby sparing healthy cells. In this review, we describe approved ADCs and discuss their modes of action, together with medicinal chemical aspects, to evaluate the potential for improvement and to combat tumor-acquired resistance. A recent research focus has centered on the stimulation of immune responses to induce immunogenic cell death and the influence on the tumor microenvironment to enhance bystander effects.

Sacituzumab govitecan: past, present and future of a new antibody-drug conjugate and future horizon

Sacituzumab govitecan (SG) is a new antibody-drug conjugate directed against the cell-surface antigen Trop-2. Characteristics of the linker connecting the payload SN-38 to the antibody allows SG to kill tumor cells expressing Trop-2 and also the adjacent tumor cells (bystander effect). SG showed efficacy and safety in several epithelial tumors. The phase III ASCENT trial led to the approval of SG (10 mg/kg, d1,8 q3w) in patients with advanced or metastatic triple-negative breast cancer (TNBC) who have received ≥2 prior systemic therapies, including ≥1 for metastatic disease. The phase III TROPiCS-02 trial in heavily pretreated advanced hormone receptor (HR)-positive breast cancer has recently shown an improvement in progression-free survival for patients treated with SG compared to single-agent chemotherapy. The phase III post-neoadjuvant SASCIA study in early high-risk TNBC and HR-positive breast cancer is currently recruiting patients.

Safety analyses from the phase 3 ASCENT trial of sacituzumab govitecan in metastatic triple-negative breast cancer

Sacituzumab govitecan (SG) is an anti-Trop-2 antibody-drug conjugate with an SN-38 payload. In the ASCENT study, patients with metastatic triple-negative breast cancer (mTNBC) relapsed/refractory to ≥2 prior chemotherapy regimens (≥1 in the metastatic setting), received SG or single-agent treatment of physician's choice (eribulin, vinorelbine, capecitabine, or gemcitabine). This ASCENT safety analysis includes the impact of age and UGT1A1 polymorphisms, which hinder SN-38 detoxification. SG demonstrated a manageable safety profile in patients with mTNBC, including those ≥65 years; neutropenia/diarrhea are key adverse events (AE). Patients with UGT1A1 *28/*28 genotype versus those with 1/*28 and *1/*1 genotypes had higher rates of grade ≥3 SG-related neutropenia (59% vs 47% and 53%), febrile neutropenia (18% vs 5% and 3%), anemia (15% vs 6% and 4%), and diarrhea (15% vs 9% and 10%), respectively. Individuals with UGT1A1 *28/*28 genotype should be monitored closely; active monitoring and routine AE management allow optimal therapeutic exposure of SG.

Targeted therapy for breast cancer: An overview of drug classes and outcomes

The last 25 years have seen significant growth in new therapeutic options for breast cancer, termed targeted therapies based on their ability to block specific pathways known to drive breast tumor growth and survival. Introduction of these drugs has been made possible through advances in the understanding of breast cancer biology. While the promise of targeted therapy for breast cancer has been clear for some time, the experience of the clinical use of multiple drugs and drug classes allows us to now present a summary and perspective as to the success and impact of this endeavor. Here we will review breast cancer targeted therapeutics in clinical use. We will provide the rationale for their indications and summarize clinical data in patients with different breast cancer subtypes, their impact on breast cancer progression and survival and their major adverse effects. The focus of this review will be on the development that has occurred within classes of targeted therapies and subsequent impact on breast cancer patient outcomes. We will conclude with a perspective on the role of targeted therapy in breast cancer treatment and highlight future areas of development.

Trophoblast Cell Surface Antigen 2 gene (TACSTD2) expression in primary breast cancer

PURPOSE

Trophoblast Cell Surface Antigen 2 (TROP2) is a glycoprotein expressed in many cancers. A TROP2 antibody-drug conjugate (ADC) was effective in metastatic triple-negative breast cancer (TNBC). We studied TROP2 gene (TACSTD2) expression and associations with tumor and clinical characteristics, as well as selected external genes in primary breast cancer.

METHODS

TACSTD2 gene expression was evaluated using microarray data from I-SPY 1 (n = 149), METABRIC (n = 1992), and TCGA (n = 817). Associations with clinical features (Kruskal-Wallis test, all datasets), chemotherapy response (Wilcoxon rank sum test, I-SPY 1), recurrence free survival (Cox proportional hazard model, I-SPY 1 and METABRIC), and selected genes (Pearson correlations, all datasets) were determined.

RESULTS

TACSTD2 gene expression was detectable in all breast cancer subtypes, with a wide range of expression (all datasets). TACSTD2 gene expression was lower in HER2 + than HR + /HER2- and TNBC (METABRIC: p = 0.03, TCGA p = 0.007), and in HER2 + enriched and luminal B breast cancer (METABRIC: p < 0.001, TCGA: p < 0.001). TACSTD2 expression was higher in grade I vs. II/III tumors (METABRIC: p < 0.001). No association with chemotherapy response (I-SPY 1) or recurrence free survival (I-SPY 1 and METABRIC) was seen. TACSTD2 has significant positive correlations with the expression of epithelial/adhesion genes and proliferative genes, but was inversely correlated with immune genes.

CONCLUSION

TACSTD2 gene expression was seen in all breast cancer subtypes particularly luminal A and TNBC, and correlated with the expression of genes involved in cell epithelial transformation, adhesion, and proliferation, which contribute to tumor growth. These results support the investigation of TROP2 ADC in all subtypes of breast cancer.

Joint Disposition Properties and Comprehensive Pharmacokinetic Characterization of Antibody–Drug Conjugates

Antibody–drug conjugates (ADCs) comprise 3 distinct parts: a specific antibody carrier (mAb), a linker, and a cytotoxic payload. Typical pharmacokinetic (PK) characterization of ADCs remains fragmented using separate noncompartmental analyses (NCA) of individual analytes, offering little insight into the dynamic relationships among the ADC components, and the safety and efficacy implications. As a result, it is exceedingly difficult to compare ADCs in terms of favorable PK characteristics. Therefore, there is a need for characterizing ADCs using the joint disposition properties critical for understanding the fate of an ADC complex and clinical implications. In this communication, we describe 3 joint disposition metrics (JDMs) for integrated NCA of ADCs based on a combination of common analytes of ADC, payload, conjugated payload, and total mAb. These JDMs were derived, each in a simple form of a ratio between appropriate PK parameters of two analytes, from the presumed drug delivery scheme behind typical ADC designs, in terms of (1) linker stability, (2) therapeutic exposure ratio, and (3) effective drug-to-antibody ratio in vivo. The validity of the JDM-based PK characterization was examined against model-based analyses via their applications to 3 clinical candidates: PF-06650808, PF-06647020, and PF-06664178. For instance, the linker stability estimates for PF-06650808, PF-06647020, and PF-06664178 were 0.31, 0.14, and 0.096, respectively, from the JDM-based analyses vs. 0.23, 0.11, and 0.086 by the model-based approach. Additionally, the JDMs were estimated for a number of FDA-approved or otherwise well-documented ADCs, showing their utilities in comparing ADCs in terms of favorable PK characteristics.

Graphical Abstract

Modern developments in germline pharmacogenomics for oncology prescribing

The integration of genomic data into personalized treatment planning has revolutionized oncology care. Despite this, patients with cancer remain vulnerable to high rates of adverse drug events and medication inefficacy, affecting prognosis and quality of life. Pharmacogenomics is a field seeking to identify germline genetic variants that contribute to an individual's unique drug response. Although there is widespread integration of genomic information in oncology, somatic platforms, rather than germline biomarkers, have dominated the attention of cancer providers. Patients with cancer potentially stand to benefit from improved integration of both somatic and germline genomic information, especially because the latter may complement treatment planning by informing toxicity risk for drugs with treatment-limiting tolerabilities and narrow therapeutic indices. Although certain germline pharmacogenes, such as TPMT, UGT1A1, and DPYD, have been recognized for decades, recent attention has illuminated modern potential dosing implications for a whole new set of anticancer agents, including targeted therapies and antibody-drug conjugates, as well as the discovery of additional genetic variants and newly relevant pharmacogenes. Some of this information has risen to the level of directing clinical action, with US Food and Drug Administration label guidance and recommendations by international societies and governing bodies. This review is focused on key new pharmacogenomic evidence and oncology-specific dosing recommendations. Personalized oncology care through integrated pharmacogenomics represents a unique multidisciplinary collaboration between oncologists, laboratory science, bioinformatics, pharmacists, clinical pharmacologists, and genetic counselors, among others. The authors posit that expanded consideration of germline genetic information can further transform the safe and effective practice of oncology in 2022 and beyond.