7LBA Safety, activity, and response durability assessment of single agent rovalpituzumab tesirine, a delta-like protein 3 (DLL3)-targeted antibody drug conjugate (ADC), in small cell lung cancer (SCLC)

Recent advances of antibody drug conjugates for clinical applications

Antibody drug conjugates (ADCs) normally compose of a humanized antibody and small molecular drug via a chemical linker. After decades of preclinical and clinical studies, a series of ADCs have been widely used for treating specific tumor types in the clinic such as brentuximab vedotin (Adcetris®) for relapsed Hodgkin's lymphoma and systemic anaplastic large cell lymphoma, gemtuzumab ozogamicin (Mylotarg®) for acute myeloid leukemia, ado-trastuzumab emtansine (Kadcyla®) for HER2-positive metastatic breast cancer, inotuzumab ozogamicin (Besponsa®) and most recently polatuzumab vedotin-piiq (Polivy®) for B cell malignancies. More than eighty ADCs have been investigated in different clinical stages from approximately six hundred clinical trials to date. This review summarizes the key elements of ADCs and highlights recent advances of ADCs, as well as important lessons learned from clinical data, and future directions.

The evolving landscape of immunotherapy in small-cell lung cancer: A focus on predictive biomarkers

Small cell lung cancer (SCLC) was defined as a "recalcitrant cancer" because of its dismal prognosis and lack of outcome improvements in the last 30 years. Immunotherapy with checkpoint inhibitors revolutionized treatment in many cancer types and results from the IMpower133 study, a double-blind placebo-controlled phase III trial, showed overall survival benefit for atezolizumab when added to standard platinum-etoposide chemotherapy in first-line SCLC setting for the first time since years. Trials with other checkpoint inhibitors, e.g. pembrolizumab, durvalumab, nivolumab and ipilimumab, are ongoing in various settings, but, to date, there are no defined factors to identify patients who are more likely to benefit from such treatments. This review summarizes results of immunotherapy trials in SCLC for first-line, maintenance and further-line therapies for single-agents and combinations with checkpoint inhibitors. Predictive factors from these trials are reviewed in order to identify their clinical value, with particular emphasis on PD-L1 expression on both tumor cells and in stroma, especially in pembrolizumab-treated patients, and tumor mutational burden, for patients treated with the ipilimumab and nivolumab combination.

Integrative genomic profiling of large-cell neuroendocrine carcinomas reveals distinct subtypes of high-grade neuroendocrine lung tumors

Pulmonary large-cell neuroendocrine carcinomas (LCNECs) have similarities with other lung cancers, but their precise relationship has remained unclear. Here we perform a comprehensive genomic (n = 60) and transcriptomic (n = 69) analysis of 75 LCNECs and identify two molecular subgroups: “type I LCNECs” with bi-allelic TP53 and STK11/KEAP1 alterations (37%), and “type II LCNECs” enriched for bi-allelic inactivation of TP53 and RB1 (42%). Despite sharing genomic alterations with adenocarcinomas and squamous cell carcinomas, no transcriptional relationship was found; instead LCNECs form distinct transcriptional subgroups with closest similarity to SCLC. While type I LCNECs and SCLCs exhibit a neuroendocrine profile with ASCL1^high/DLL3^high/NOTCH^low, type II LCNECs bear TP53 and RB1 alterations and differ from most SCLC tumors with reduced neuroendocrine markers, a pattern of ASCL1^low/DLL3^low/NOTCH^high, and an upregulation of immune-related pathways. In conclusion, LCNECs comprise two molecularly defined subgroups, and distinguishing them from SCLC may allow stratified targeted treatment of high-grade neuroendocrine lung tumors.

The molecular nature of large-cell neuroendocrine lung carcinomas (LCNEC) has remained unclear. Here, the authors show LCNECs represent a distinct transcriptional subgroup among lung cancers and comprise two molecular subgroups, type I (TP53 and STK11/KEAP1 alterations) and type II (TP53 and RB1 inactivation).

Advances in Small Cell Lung Cancer

Small cell lung cancer (SCLC) is an aggressive neuroendocrine tumor characterized by early metastatic spread and responsiveness to initial therapy. The incidence of SCLC has been declining in the United States in parallel with the decreasing prevalence of cigarette smoking. Limited stage disease is potentially curable with chemoradiotherapy followed by cranial irradiation. Extensive stage disease is incurable, but systemic chemotherapy can improve quality of life and prolong survival. Nearly all patients relapse with chemoresistant disease. Molecularly targeted therapy has failed to yield convincing clinical benefits. Nevertheless, many biologically rational strategies, including immune checkpoint inhibition, show promise in ongoing clinical trials.

Novel therapeutic targets on the horizon for lung cancer

Lung cancer is a leading cause of cancer-related mortality worldwide, and is classically divided into two major histological subtypes: non-small-cell lung cancer (NSCLC) and small-cell lung cancer (SCLC). Although NSCLC and SCLC are considered distinct entities with different genomic landscapes, emerging evidence highlights a convergence in therapeutically relevant targets for both histologies. In adenocarcinomas with defined alterations such as EGFR mutations and ALK translocations, targeted therapies are now first-line standard of care. By contrast, many experimental and targeted agents remain largely unsuccessful for SCLC. Intense preclinical research and clinical trials are underway to exploit unique traits of lung cancer, such as oncogene dependency, DNA damage response, angiogenesis, and cellular plasticity arising from presence of cancer stem cell lineages. In addition, the promising clinical activity observed in NSCLC in response to immune checkpoint blockade has spurred great interest in the field of immunooncology, with the scope to develop a diverse repertoire of synergistic and personalised immunotherapeutics. In this Review, we discuss novel therapeutic agents for lung cancer that are in early-stage development, and how prospective clinical trials and drug development may be shaped by a deeper understanding of this heterogeneous disease.

Seeking New Approaches to Patients With Small Cell Lung Cancer

The fundamental approach to the treatment of small cell lung cancer (SCLC) has not changed in the last several decades, with most advances being restricted to improved radiation approaches. The standard first-line chemotherapy regimen in the United States and Europe remains cisplatin or carboplatin plus etoposide in the treatment of limited stage (LS-SCLC) and extensive stage (ES-SCLC) disease. Radiation therapy is administered to those patients with LS-SCLC, whose cancer is confined to the chest in a single tolerable radiation field. This article will summarize a number of exciting observations regarding the biology of SCLC and how a deeper understanding of newly integrated targets and target pathways may lead to new and better therapeutic approaches in the near future.

Design and Synthesis of Tesirine, a Clinical Antibody-Drug Conjugate Pyrrolobenzodiazepine Dimer Payload

Pyrrolobenzodiazepine dimers are an emerging class of warhead in the field of antibody-drug conjugates (ADCs). Tesirine (SG3249) was designed to combine potent antitumor activity with desirable physicochemical properties such as favorable hydrophobicity and improved conjugation characteristics. One of the reactive imines was capped with a cathepsin B-cleavable valine-alanine linker. A robust synthetic route was developed to allow the production of tesirine on clinical scale, employing a flexible, convergent strategy. Tesirine was evaluated in vitro both in stochastic and engineered ADC constructs and was confirmed as a potent and versatile payload. The conjugation of tesirine to anti-DLL3 rovalpituzumab has resulted in rovalpituzumab-tesirine (Rova-T), currently under evaluation for the treatment of small cell lung cancer.

New and emerging developments in extensive-stage small cell lung cancer therapeutics

PURPOSE OF REVIEW

Extensive-stage small cell lung cancer (ES-SCLC) remains a disease with a dismal prognosis, with median survival of approximately 8-10 months. Despite many attempts to develop effective systemic therapies, very little progress has been made in the last several decades. Platinum-based combination chemotherapy remains the standard of care in the first-line setting and is associated with high response rates albeit short-lived. However, there have been recent advances in the use of radiation therapy, as well as new insights into the biology of SCLC.

RECENT FINDINGS

Some of the most appreciable advances in the last decade have involved the use of local radiation therapy. With the use of new laboratory techniques such as genomic sequencing, there remains promise of rationally targeted drug development. Circulating tumor cell research may also provide insights to SCLC biology and further refine treatment.

SUMMARY

Systemic therapy for SCLC has changed little over the past 30 years with the most significant advances in ES-SCLC relating to radiotherapy rather than systemic therapy. The effectiveness of prophylactic cranial irradiation and thoracic radiotherapy has renewed interest in therapeutics focused on the modulation of DNA damage or repair. Recent developments in genomic sequencing and immunotherapy may translate to new treatment paradigms for SCLC.