Tumor-Targeted Drug Conjugates as an Emerging Novel Therapeutic Approach in Small Cell Lung Cancer (SCLC)

Small Molecule-Drug Conjugates: Opportunities for the Development of Targeted Anticancer Drugs

Conventional chemotherapy is insufficient for precise cancer treatment due to its lack of selectivity and inevitable side effects. Targeted drugs have emerged as a promising solution for precise cancer treatment. A common strategy is to conjugate therapeutic agents with ligands that can specifically bind to tumor cells, providing targeted therapy. Similar to the more successful antibody drug conjugates (ADCs), small molecule drug conjugates (SMDCs) are another promising class of targeted drugs, consisting of three parts: targeting ligand, cleavable linker and payload. Compared to ADCs, SMDCs have the advantages of smaller size, better permeability, simpler preparation process and non-immunogenicity, making them a promising alternative to ADCs. This review describes the characteristics of the targeting ligand, linker and payload of SMDCs and the criteria for selecting a suitable one. We also discuss recently reported SMDCs and list some successful SMDCs that have entered clinical trials.

Usefulness of baseline immature reticulocyte fraction to mature reticulocyte fraction ratio (IMR) as A prognostic predictor for patients with small cell lung cancer

Background

Small cell lung cancer (SCLC) has a strong invasive ability and a high degree of malignancy, so accurate prognosis prediction is crucial for making the most favorable treatment decision.Unfortunately, there is a scarcity of prognostic indicators specific to SCLC. Reticulocyte levels in blood parameters have been linked to the prognosis of various malignancies. Given SCLC's aggressive characteristics, identifying reliable prognostic markers, such as reticulocyte counts, becomes pivotal in enhancing prognostic accuracy and guiding effective therapeutic strategies.

Objective

This study aimed to evaluate the predictive power of the immature reticulocyte fraction (IRF) to mature reticulocyte fraction (MRF) ratio (IMR) for survival outcomes in patients with SCLC.

Materials and methods

A retrospective analysis was conducted on 192 patients with small cell lung cancer (SCLC). The median values of various prognostic indicators, such as IMR, IRF, MRF, reticulocyte count (RET), SII (systemic immune-inflammatory index), were utilized as cutoff points, categorizing patients into high and low groups. The Kaplan-Meier method, univariate, multivariate analyses Cox regression, and C-index were used to analyze the prognostic factors for overall survival (OS).

Results

In our cohort, 138 (71.9 %) were male, 119 (62 %) were smokers, and 82 (57.3 %) were older than 60 years old. The median survival time was 18.15 months.Higher mortality was observed in the high IMR and high IRF groups, while the high MRF group exhibited lower mortality. At the same time, mortality was lower in the high MRF group. Univariate analysis showed that smoking history (P = 0.006), tumor stage (P = 0.002), chemotherapy cycle (P = 0.014), IMR (P = 0.01), and many other factors significantly affected the prognosis of SCLC. Multivariate analysis demonstrated that elevated IMR was an independent adverse predictor of OS (P = 0.039, HR = 0.330). Spearman test confirmed that the prognostic indicators IRF, IMR, and SII were positively correlated with the overall survival rate of patients with SCLC. Kaplan-Meier analysis showed that the OS rate of patients with high IMR was significantly worse (P = 0.0096). In addition, we found that IMR was superior to IRF in distinguishing patients with different outcomes in the low and high groups (P < 0.05). Our novel integration index, combining IMR with the TNM stage system and SII index, exhibited superior prognostic value compared to the original index. Additionally, the combination of prognostic indicators IMR and SII significantly stratified stage I-II SCLC patients (P ＜0.05).

Conclusions

The prognostic index based on peripheral blood IMR stands out as an independent predictor for SCLC patients pre-treatment. Its accessibility through routine blood analysis facilitates immediate clinical application without requiring prolonged scientific research validation. The integration of IMR with the TNM score enhances survival prediction and risk stratification. Notably, when combined with the SII score, the new IMR index demonstrates significant improvements in prognostication for stage I-II small cell lung cancer.

Toripalimab combined with anlotinib for recurrent extensive‑stage small‑cell lung cancer: A case report

The 5-year survival rate of patients with extensive-stage small cell lung cancer (ES-SCLC) is <8%; therefore there is an urgent need for more effective treatment. Although immune checkpoint inhibitors have been widely used to treat lung cancer, the efficacy of anti-programmed death 1 therapy for SCLC is limited due to the abnormal vascular state of the tumour microenvironment. A 66-year-old man who was diagnosed with ES-SCLC and performance status (PS) 3 received first-line chemotherapy but experienced recurrence. Repeated stage IV thrombocytopenia hindered completion of second-line chemotherapy. Therefore, the patient was treated with a combination of toripalimab and anlotinib. After two cycles, the patient showed a partial response to therapy; a long-lasting curative benefit extending 20 months was achieved with PS 1. This novel and effective combined immune/anti-angiogenic therapy paradigm for patients with relapsed ES-SCLC and poor PS requires prospective clinical trials.

The blood proteome of imminent lung cancer diagnosis

Identification of risk biomarkers may enhance early detection of smoking-related lung cancer. We measured between 392 and 1,162 proteins in blood samples drawn at most three years before diagnosis in 731 smoking-matched case-control sets nested within six prospective cohorts from the US, Europe, Singapore, and Australia. We identify 36 proteins with independently reproducible associations with risk of imminent lung cancer diagnosis (all p < 4 × 10-5). These include a few markers (e.g. CA-125/MUC-16 and CEACAM5/CEA) that have previously been reported in studies using pre-diagnostic blood samples for lung cancer. The 36 proteins include several growth factors (e.g. HGF, IGFBP-1, IGFP-2), tumor necrosis factor-receptors (e.g. TNFRSF6B, TNFRSF13B), and chemokines and cytokines (e.g. CXL17, GDF-15, SCF). The odds ratio per standard deviation range from 1.31 for IGFBP-1 (95% CI: 1.17-1.47) to 2.43 for CEACAM5 (95% CI: 2.04-2.89). We map the 36 proteins to the hallmarks of cancer and find that activation of invasion and metastasis, proliferative signaling, tumor-promoting inflammation, and angiogenesis are most frequently implicated.

Dual Targeted Delivery of Liposomal Hybrid Gold Nano-Assembly for Enhanced Photothermal Therapy against Lung Carcinomas

The delivery and accumulation of therapeutic drugs into cancer cells without affecting healthy cells are a major challenge for antitumor therapy. Here, we report the synthesis of a liposomal hybrid gold nano-assembly with enhanced photothermal activity for lung cancer treatment. The core components of the nano-assembly include gold nanorods coated with a mesoporous silica shell that offers an excellent drug-loading surface for encapsulation of doxorubicin. To enhance the photothermal capacity of nano-assembly, IR 780 dye was loaded inside a thermo-sensitive liposome, and then, the core nano-assembly was wrapped within the liposome, and GE-11 peptide and folic acid were conjugated onto the surface of the liposome to give the final nano-assembly [(GM@Dox) LI]-PF. The dual targeting approach of [(GM@Dox) LI]-PF leads to enhanced cellular uptake and improves the accumulation of nano-assemblies in cancer cells that overexpress the epidermal growth factor receptor and folate. The exposure of near-infrared laser irradiation can trigger photothermal-induced structural disruption of the nano-assembly, which allows for the precise and controllable release of Dox at targeted sites. Additionally, chemo-photothermal therapy was shown to be 11 times more effective in cancer cell treatment when compared to Dox alone. Our systematic study suggests that the nano-assemblies facilitate the cancer cells undergoing apoptosis via an intrinsic mitochondrial pathway that can be directly triggered by the chemo-photothermal treatment. This study offers an appealing candidate that holds great promise for synergistic cancer treatment.

Synthesis and Evaluation of a Non-Peptide Small-Molecule Drug Conjugate Targeting Integrin αVβ3

An integrin α_Vβ₃-targeting linear RGD mimetic containing a small-molecule drug conjugate (SMDC) was synthesized by combining the antimitotic agent monomethyl auristatin E (MMAE), an enzymatically cleavable Val-Ala-PABC linker with a linear conjugable RGD mimetic. The structure proposal for the conjugable RGD mimetic was suggested upon the DAD mapping analysis of a previously synthesized small-molecule RGD mimetic array based on a tyrosine scaffold. Therefore, a diversifying strategy was developed as well as a novel method for the partial hydrogenation of pyrimidines in the presence of the hydrogenolytically cleavable Cbz group. The small-molecule RGD mimetics were evaluated in an ELISA-like assay, and the structural relationships were analyzed by DAD mapping revealing activity differences induced by structural changes as visualized in dependence on special structural motifs. This provided a lead structure for generation of an SMDC containing the antimitotic drug MMAE. The resulting SMDC containing a linear RGD mimetic was tested in a cell adhesion and an in vitro cell viability assay in comparison to reference SMDCs containing cRGDfK or cRADfK as the homing device. The linear RGD SMDC and the cRGDfK SMDC inhibited adhesion of α_Vβ₃-positive WM115 cells to vitronectin with IC₅₀ values in the low µM range, while no effect was observed for the α_Vβ₃-negative M21-L cell line. The cRADfK SMDC used as a negative control was about 30-fold less active in the cell adhesion assay than the cRGDfK SMDC. Conversely, both the linear RGD SMDC and the cRGDfK SMDC are about 55-fold less cytotoxic than MMAE against the α_Vβ₃-positive WM115 cell line with IC50 values in the nM range, while the cRADfK SMDC is 150-fold less cytotoxic than MMAE. Hence, integrin binding also influences the antiproliferative activity giving a targeting index of 2.8.

Antibody drug conjugates in gastrointestinal cancer: From lab to clinical development

The antibody-drug conjugates (ADCs) are one the fastest growing biotherapeutics in oncology and are still in their infancy in gastrointestinal (GI) cancer for clinical applications to improve patient survival. The ADC based approach is developed with tumor specific antigen, antibody carrying cytotoxic agents to precisely target and deliver chemotherapeutics at the tumor site. To date, 11 ADCs have been approved by US-FDA, and more than 80 are in the clinical development phase for different oncological indications. However, The ADCs based therapies in GI cancers are still far from having high-efficient clinical outcomes. The limited success of these ADCs and lessons learned from the past are now being used to develop a newer generation of ADC against GI cancers. In this review, we did a comprehensive assessment of the key components of ADCs, including tumor marker, antibody, cytotoxic payload, and linkage strategy, with a focus on technical improvement and some future trends in the pipeline for clinical translation. The various preclinical and clinical ADCs used in gastrointestinal malignancies, their target, composition and bioconjugation, along with preclinical and clinical outcomes, are discussed. The emphasis is also given to new generation ADCs employing novel mAb, payload, linker, and bioconjugation methods are also included.

Carrelizumab combined with anlotinib in the treatment of extensive-stage small cell lung cancer: A case report

RATIONALE

The emergence of immune checkpoint inhibitors has brought new breakthroughs in the treatment of small cell lung cancer (SCLC). Programmed cell death-ligand 1 inhibitors combined with chemotherapy have been approved for the first-line treatment of extensive-stage small cell lung cancer (ES-SCLC). However, programmed death 1 inhibitors have limited efficacy in the treatment of SCLC. The reason may be related to the abnormal vascular state in the tumor microenvironment.

PATIENT CONCERNS

A 55-year-old male patient, presenting cough and sputum for 1 month.

DIAGNOSES

The patient was clinically diagnosed with SCLC and staged as ES-SCLC.

INTERVENTIONS

Etoposide combined with lobaplatin treatment every 3 weeks for 4 cycles, evaluate as progressive disease. On the basis of the original plan, combined with camrelizumab for 2 cycles, evaluation as progressive disease. Then, the patient was treated with intravenous infusion of camrelizumab plus oral anlotinib. After 4 cycles, evaluation as partial response. Then we continued to use camrelizumab combined with anlotinib treatment for the patient. At the end of 26 cycles, the chest computed tomography examination revealed that the patient had achieved complete remission.

OUTCOMES

After treated with carrelizumab combined with anlotinib for 26 cycles, the curative effect was evaluated as complete remission, progression-free survival was 24 months and there was no immune-related adverse reaction during treatment period. Besides, the patient developed complicated hand-foot syndrome, but this symptom was significantly relieved after reducing the dosage of anlotinib.

LESSONS

In this case, antiangiogenesis combined with programmed death 1 inhibitors significantly inhibited tumor progression. It also indicated that anlotinib concurrent carrelizumab may be a superior choice for ES-SCLC. Further clinical trials required to confifirm its effificacy and safety.

Prognostic Relevance of Concordant Expression CD69 and CD56 in Response to Bortezomib Combination Therapy in Multiple Myeloma Patients

OBJECTIVE

Multiple myeloma is an incurable hematological malignancy. Currently, the use of proteasome inhibitors could be superior to chemotherapy-based regimen in the treatment of this disease. However, resistance to bortezomib combination therapy still occurs in some patients. So, this research work aims to assess CD69 and CD56 expression in these cases and their relation to the response to therapy.

MATERIALS AND METHODS

Immunophenotyping by 4-color multi-parameter flow cytometry was carried out on 98 multiple myeloma cases. Clonal plasma cells were gated by co-expression of CD38 with CD138 with low SSC, negative or dim CD45.

RESULTS

Double negative CD69 and CD56 (47.9%) multiple myeloma cases were associated with high serum β2 microglobulin, creatinine, calcium and low serum albumin. There was also a significant correlation between the absence of these markers with osteolytic lesions and unfavorable cytogenetic t (4;14) (p < 0.001). Moreover, there was a highly significant correlation between CD69- and CD56- with non-response to bortezomib combination therapy in multiple myeloma patients (p < 0.0001). Regression analysis for the prediction of non- response to treatment in these cases using different prognostic indicators revealed that high serum β2 microglobulin, unfavorable cytogenetic, advanced stage, and low expression of CD69 and CD56 were poor predictors of non-response.

CONCLUSION

CD69 in association with CD56 could be an independent prognostic factor in multiple myeloma cases. It could be used in the routine laboratory assessment for refining stratification and timely therapeutic decision for highly cost therapy in developing countries.

Evaluation of the Small-molecule BRD4 Degrader CFT-2718 in Small-cell Lung Cancer and Pancreatic Cancer Models

Targeted, catalytic degradation of oncoproteins using heterobifunctional small molecules is an attractive modality, particularly for hematologic malignancies, which are often initiated by aberrant transcription factors and are challenging to drug with inhibitors. BRD4, a member of the bromodomain and extraterminal family, is a core transcriptional and epigenetic regulator that recruits the P-TEFb complex, which includes Cdk9 and cyclin T, to RNA polymerase II (pol II). Together, BRD4 and CDK9 phosphorylate serine 2 (pSer2) of heptad repeats in the C-terminal domain of RPB1, the large subunit of pol II, promote transcriptional elongation. Small-molecule degraders of BRD4 have shown encouraging efficacy in preclinical models for several tumor types but less efficacy in other cancers including small-cell lung cancer (SCLC) and pancreatic cancer. Here, we evaluated CFT-2718, a new BRD4-targeting degrader with enhanced catalytic activity and in vivo properties. In vivo, CFT-2718 has significantly greater efficacy than the CDK9 inhibitor dinaciclib in reducing growth of the LX-36 SCLC patient-derived xenograft (PDX) model and performed comparably to dinaciclib in limiting growth of the PNX-001 pancreatic PDX model. In vitro, CFT-2718 reduced cell viability in four SCLC and two pancreatic cancer models. In SCLC models, this activity significantly exceeded that of dinaciclib; furthermore, CFT-2718 selectively increased the expression of cleaved PARP, an indicator of apoptosis. CFT-2718 caused rapid BRD4 degradation and reduced levels of total and pSer2 RPB1 protein. These and other findings suggest that BRD-mediated transcriptional suppression merits further exploration in the setting of SCLC.

Single- versus Dual-Targeted Nanoparticles with Folic Acid and Biotin for Anticancer Drug Delivery

Cancer is one of the major causes of death worldwide and its treatment remains very challenging. The effectiveness of cancer therapy significantly depends upon tumour-specific delivery of the drug. Nanoparticle drug delivery systems have been developed to avoid the side effects of the conventional chemotherapy. However, according to the most recent recommendations, future nanomedicine should be focused mainly on active targeting of nanocarriers based on ligand-receptor recognition, which may show better efficacy than passive targeting in human cancer therapy. Nevertheless, the efficacy of single-ligand nanomedicines is still limited due to the complexity of the tumour microenvironment. Thus, the NPs are improved toward an additional functionality, e.g., pH-sensitivity (advanced single-targeted NPs). Moreover, dual-targeted nanoparticles which contain two different types of targeting agents on the same drug delivery system are developed. The advanced single-targeted NPs and dual-targeted nanocarriers present superior properties related to cell selectivity, cellular uptake and cytotoxicity toward cancer cells than conventional drug, non-targeted systems and single-targeted systems without additional functionality. Folic acid and biotin are used as targeting ligands for cancer chemotherapy, since they are available, inexpensive, nontoxic, nonimmunogenic and easy to modify. These ligands are used in both, single- and dual-targeted systems although the latter are still a novel approach. This review presents the recent achievements in the development of single- or dual-targeted nanoparticles for anticancer drug delivery.

Small molecule drug conjugates (SMDCs): an emerging strategy for anticancer drug design and discovery

Mechanisms of how SMDCs work. Small molecule drugs are conjugated with the targeted ligand using pH sensitive linkers which allow the drug molecule to get released at lower lysosomal pH. It helps to accumulate the chemotherapeutic agents to be localized in the tumor environment upon cleaving of the pH-labile bonds.

STK1p as a prognostic biomarker for overall survival in non-small-cell lung carcinoma, based on real-world data

Aim:

A prospective investigation of serum thymidine kinase 1 concentration (STK1p) was performed to evaluate its prognostic value in patients with non-small-cell lung carcinoma (NSCLCs).

Patients & methods:

The STK1p values of 127 patients were determined by an enhanced chemiluminescent dot blot assay. The patients were recruited from March 2011 to December 2017.

Results:

Kaplan–Meier plot showed that patients with elevated STK1p values had worse overall survival (OS), especially patients of early/middle stages. Multi-variable COX regression showed that STK1p value and combined treatment surgery + chemotherapy were independent prognostic factors for favorable OS.

Conclusion:

STK1p is helpful in predicting OS of early/middle stages (I–IIIA) NSCLCs patients following a nonrandomized individual adapted treatment, but is may be not recommended in advanced stages (IIIB + IV) of NSCLCs.

Lung cancer is one of the most common types of tumors, with a high mortality rate. We investigate if thymidine kinase 1 in serum (STK1p) is a reliable prognostic marker for survival in non-small-cell lung carcinoma. We recruited 127 patients in this study. STK1p level was determined using a high-sensitive chemiluminescent dot blot assay. Patients with elevated STK1p values had worse overall survival, especially patients in the early/middle cancer stages. Analysis showed that STK1p is an independent prognostic factors for overall survival. We concluded that STK1p is helpful predicting the efficacy of treatment in non-small-cell lung carcinoma for those in the early/middle stages.

Successful treatment of a patient with small cell lung cancer receiving hemodialysis, with concurrent oral etoposide and radiotherapy: A case report

INTRODUCTION

Small cell lung cancer (SCLC) is an aggressive malignancy that progresses rapidly and easily relapses. To the best of our knowledge, advances have been minimal for decades and the first-line treatment is still platinum-etoposide and radiotherapy. However, elderly patients with severe renal failure who suffer from SCLC usually show more serious drug-related side effects. A large proportion of them cannot tolerate the standard treatment, and their prognosis is poorer compared with that of younger patients. Presently, oral etoposide capsules may be accepted as a replaceable option. We report the case of a male patient with SCLC on hemodialysis who was successfully treated with concurrent oral etoposide monotherapy and radiotherapy and achieved excellent outcomes.

PATIENT'S CONCERNS

A 63-year-old man with severe renal failure was diagnosed with SCLC.

PRIMARY DIAGNOSES

SCLC was diagnosed using transbronchial biopsy.

INTERVENTIONS

He received concomitant single-agent oral etoposide (6 cycles) and local radiotherapy. Etoposide 100 mg once daily combined with thoracic radiation treatment (2 Gy/f, total DT: 50 Gy/25 f), was subsequently followed by prophylactic cranial irradiation plus anlotinib.

OUTCOMES

The patient achieved complete response after 1 cycle and the subsequent treatment was effective without any kidney damage and other severe side effects.

CONCLUSION

Though etoposide capsule is an old drug, its use should be considered in SCLC patients with renal insufficiency undergoing hemodialysis. However, treatment guidelines and research data for such patients are still lacking and further studies are needed. Although recent research focuses mainly on new drugs, some old drugs like etoposide which can bring unexpected positive effects should not be neglected.

NRXN1 as a novel potential target of antibody-drug conjugates for small cell lung cancer

Small cell lung cancer (SCLC) is a high-grade malignancy, and treatment strategies have not changed for decades. In this study, we searched for novel targets for antibody-drug conjugate (ADC) therapy for SCLC. We identified transmembrane proteins overexpressed specifically in SCLC with little or no expression in normal tissues and decided to focus on the cell adhesion molecule neurexin-1 (NRXN1). The cell surface overexpression of NRXN1 was confirmed using flow cytometry in SCLC cell lines (SHP77 and NCI-H526). The combination of a primary anti-NRXN1 monoclonal antibody and a secondary ADC exhibited anti-tumor activity in SCLC cell lines. Moreover, the knockout of NRXN1 in SHP77 cells resulted in a loss of the anti-tumor activity of NRXN1-mediated ADC therapy. Thus, NRXN1 could be a novel target for ADC therapy for the treatment of SCLC that is worth further research.

SR9009 induces a REV-ERB dependent anti-small-cell lung cancer effect through inhibition of autophagy

Rationale: The circadian clock coordinates cell proliferation and metabolism and impacts the progression of some diseases, particularly cancer. Pharmacological modulation of the circadian machinery may be an effective therapeutic approach for treating cancer. SR9009 is a specific synthetic agonist of the REV-ERBs, essential circadian clock components. However, the potential efficacy and antitumor mechanism of this drug in small-cell lung cancer (SCLC) remains poorly understood.

Methods: Here, we used chemosensitive cells (H69 and H446) and the corresponding chemoresistant cells (H69AR and H446DDP) to assess the efficacy of the REV-ERB agonist SR9009 for the treatment of SCLC in vitro and further validated the antitumor effect in subcutaneous tumor models of SCLC. Then, we determined whether REV-ERBα was correlated with the anti-SCLC effect of SR9009. Chromatin immunoprecipitation (ChIP) sequencing assays were conducted to identify potential DNA sequences directly regulated by REV-ERBα. Autophagy regulation by REV-ERBα and its possible mechanism in SR9009-based SCLC therapy were analyzed.

Results: Here, we showed that the REV-ERB agonist SR9009 is specifically lethal to both chemosensitive and chemoresistant SCLC cells. REV-ERBα was involved in the antitumor effect of SR9009 in SCLC. The core autophagy gene Atg5 was identified as a direct downstream target of REV-ERBα and was suppressed by the REV-ERB agonist SR9009 in SCLC. Furthermore, the interaction of REV-ERBα with this autophagy gene impaired autophagy activity, leading to SR9009 cytotoxicity in SCLC cells.

Principal conclusions: Our study provided a novel viewpoint indicating that the REV-ERB agonist SR9009 could be a novel and promising therapeutic strategy in first- or second-line SCLC treatment. The anti-SCLC effect of SR9009 is mediated by REV-ERB dependent suppression of autophagy via direct repression of the autophagy gene Atg5.