Small Cell Lung Cancer Transformation following Treatment in EGFR-Mutated Non-Small Cell Lung Cancer

Comprehensive molecular and clinical insights into non-small cell lung cancer transformation to small cell lung cancer with an illustrative case report

Histologic transformation to small cell lung cancer (tSCLC) is a rare but increasingly recognised mechanism of acquired resistance to tyrosine kinase inhibitors (TKI) in patients with epidermal growth factor receptor (EGFR)-positive non-small cell lung cancer (NSCLC). Beyond its acknowledged role in TKI resistance, histologic transformation to SCLC might be an important, yet under-recognised, mechanism of resistance in NSCLC treated with immunotherapy. Our review identified 32 studies that investigated tSCLC development in patients with EGFR-mutated NSCLC treated with TKI therapy and 16 case reports of patients treated with immunotherapy. It revealed the rarity of tSCLC, with a predominance of EGFR exon 19 mutations and limited therapeutic options and outcomes. Across all analysed studies in EGFR-mutated NSCLC treated with TKI therapy, the median time to tSCLC development was ∼17 months, with a median overall survival of 10 months. Histologic transformation of EGFR-mutated NSCLC to SCLC is a rare, but challenging clinical problem with a poor prognosis. A small number of documented cases of tSCLC after immunotherapy highlight the need for rebiopsies at progression to diagnose this potential resistance mechanism. Further research is needed to better understand the mechanisms underlying this phenomenon and to develop more effective treatment strategies for patients with tSCLC.

Identification of risk factors of EGFR-TKIs primary resistance in lung adenocarcinoma patients and construction of a risk predictive model: a case-control study

Background

Lung cancer is one of the malignancies with the highest incidence and mortality rates. Epidermal growth factor receptor-tyrosine kinase inhibitors (EGFR-TKIs) are recommended as the first-line treatment for patients with EGFR-mutated lung adenocarcinoma (LUAD). However, some patients with EGFR-sensitive mutations develop primary resistance to EGFR-TKIs. This study aims to analyze the clinical characteristics of LUAD patients with primary resistance to EGFR-TKIs, identify independent risk factors for primary resistance, and establish a risk predictive model to provide reference for clinical decision-making.

Methods

We collected data from LUAD patients with EGFR-sensitive mutations (19del/21L858R) who were hospitalized in our institution between 2020 and 2022 and received first-generation EGFR-TKIs with follow-up exceeding 6 months. These patients were categorized into primary resistance and sensitive groups based on treatment outcomes. We compared general clinical data, laboratory tests, and tumor-related characteristics between the two groups, analyzed risk factors for primary resistance to EGFR-TKIs, and constructed a risk predictive model. The model's predictive value was comprehensively assessed using receiver operating characteristic (ROC) curves, calibration curves, and decision curves.

Results

Serum neuron-specific enolase (NSE) concentration (P=0.03), serum pro-gastrin-releasing peptide (ProGRP) concentration (P=0.01), and Ki67 expression (P<0.001) were identified as independent risk factors for primary resistance to EGFR-TKIs in LUAD. The combined presence of these three risk factors had the highest predictive value [area under the curve (AUC) =0.975, P<0.001]. We constructed a predictive model for the risk of primary resistance to EGFR-TKIs in LUAD patients, incorporating these three parameters, and represented it through a visually interpretable nomogram. The calibration curve of the nomogram demonstrated its strong predictive ability. Further decision curve analysis indicated the model's clinical utility.

Conclusions

Based on a single-center retrospective case-control study, we identified serum NSE concentration, ProGRP concentration, and Ki67 expression as independent risk factors for primary resistance to EGFR-TKIs in LUAD patients. We constructed and validated a risk predictive model based on these findings. This predictive model holds promise for clinical application, aiding in the development of personalized treatment strategies and providing a scientific basis for early identification of primary resistance patients.

Current and Emerging Treatment Options for Patients with Metastatic EGFR-Mutated Non-small Cell Lung Cancer After Progression on Osimertinib and Platinum-Based Chemotherapy: A Podcast Discussion

Patients with metastatic epidermal growth factor receptor (EGFR)-mutated non-small cell lung cancer (NSCLC) are widely treated with osimertinib, the preferred first-line treatment option. However, disease progression inevitably occurs, driven by EGFR-dependent or EGFR-independent mechanisms of resistance. Platinum-based chemotherapy is the recommended treatment following progression with osimertinib but responses to platinum-based chemotherapy are transient. Salvage therapies, which are used after progression on platinum-based chemotherapy, have poor clinical outcomes in addition to substantial toxicity. In this podcast, we discuss the current treatment landscape and emerging therapeutic options for patients with metastatic EGFR-mutated NSCLC whose disease has progressed following treatment with osimertinib and platinum-based chemotherapy.Podcast audio available for this article.

Clinical Network Systems Biology: Traversing the Cancer Multiverse

In recent decades, cancer biology and medicine have ushered in a new age of precision medicine through high-throughput approaches that led to the development of novel targeted therapies and immunotherapies for different cancers. The availability of multifaceted high-throughput omics data has revealed that cancer, beyond its genomic heterogeneity, is a complex system of microenvironments, sub-clonal tumor populations, and a variety of other cell types that impinge on the genetic and non-genetic mechanisms underlying the disease. Thus, a systems approach to cancer biology has become instrumental in identifying the key components of tumor initiation, progression, and the eventual emergence of drug resistance. Through the union of clinical medicine and basic sciences, there has been a revolution in the development and approval of cancer therapeutic drug options including tyrosine kinase inhibitors, antibody-drug conjugates, and immunotherapy. This 'Team Medicine' approach within the cancer systems biology framework can be further improved upon through the development of high-throughput clinical trial models that utilize machine learning models, rapid sample processing to grow patient tumor cell cultures, test multiple therapeutic options and assign appropriate therapy to individual patients quickly and efficiently. The integration of systems biology into the clinical network would allow for rapid advances in personalized medicine that are often hindered by a lack of drug development and drug testing.

Etoposide/platinum plus anlotinib for patients with transformed small-cell lung cancer from EGFR-mutant lung adenocarcinoma after EGFR-TKI resistance: a retrospective and observational study

Objective

The histological conversion of lung adenocarcinoma (LUAD) into small-cell lung cancer (SCLC) is an important resistance mechanism for epidermal growth factor receptor (EGFR)-tyrosine kinase inhibitor (TKI)-resistant LUAD. Anlotinib has been recommended as the third-line treatment for SCLC patients. The efficacy of etoposide/platinum (EP) as the main treatment is very limited for patients with transformed SCLC. However, little is known about EP plus anlotinib for transformed SCLC. The present study retrospectively explored the clinical response to EP combined with anlotinib in patients with transformed SCLC from LUAD after EGFR-TKI failure.

Methods

A total of 10 patients who underwent SCLC transformation from EGFR-TKI-resistant LUAD were retrospectively reviewed from September 1, 2019, to December 31, 2022, in three regional hospitals. All of the patients were treated with the combination regimen of EP and anlotinib for four to six cycles, followed by anlotinib maintenance therapy. The clinical efficacy indices including objective response rate (ORR), disease control rate (DCR), median progression-free survival (mPFS), median overall survival (mOS), and toxicities were evaluated.

Results

The median time from EGFR-TKI treatment to SCLC conversion was 20.1 ± 2.76 months (17-24 months). Genetic examination after transformation showed that 90% of the patients retained their original EGFR gene mutations. Additional driver genes were found, including BRAF mutation (10%), PIK3CA mutation (20%), RB1 loss (50%), and TP53 mutation (60%). The ORR and DCR were 80% and 100%, respectively. The mPFS was 9.0 months (95% CI, 7.9-10.1 months), and the mOS was 14.0 months (95% CI, 12.0-15.9 months). Less than 10% of grade 3 toxicities were observed, and no grade 4 toxicity and death events were reported.

Conclusion

The EP plus anlotinib regimen appears to be a promising and safe strategy in transformed SCLC patients after EGFR-TKI resistance, which warrants further investigation.

Histological transformation to gliosarcoma with combined BRAF/MEK inhibition in BRAF V600E mutated glioblastoma

The identification of BRAF V600 mutation in multiple cancers beyond melanoma and the development of combined BRAF and MEK targeting agents have altered the landscape of tissue-agnostic precision oncology therapies with an impact on survival outcomes. Despite initial efficacy, resistance emerges, and it is pertinent to identify putative resistance mechanisms. We report a case of recurrent glioblastoma (GBM) harboring BRAF V600E alteration who initially responded to combined BRAF + MEK inhibition and subsequently developed treatment resistance by histological transformation to gliosarcoma and acquisition of oncogenic KRAS ^G12D and an NF1 ^L1083R mutation. This documented case represents an initial evidence of a developing phenomenon in cancer research as it provides the first evidence of an emergent KRAS G12D/NF1 L1083R aberration with histological transformation occurring concurrently with primary BRAF V600E-altered glioblastoma as a previously unrecognized acquired mechanism of resistance in the setting of combined BRAF and MEK inhibition. This novel finding not only sheds new light on the RAS/MAPK pathway but also highlights the potential for morphological transformation to gliosarcoma, underscoring the critical need for further investigation in this area.

Current Knowledge of Small Cell Lung Cancer Transformation from Non-Small Cell Lung Cancer

Lung cancer is the leading cause of cancer related death, and is divided into two major histological subtypes, non-small cell lung cancer (NSCLC) and small cell lung cancer (SCLC). Histological transformation from NSCLC to SCLC has been reported as a mechanism of treatment resistance in patients who received tyrosine kinase inhibitors (TKIs) targeting EGFR, ALK and ROS1 or immunotherapies. The transformed histology could be due to therapy-induced lineage plasticity or clonal selection of pre-existing SCLC cells. Evidence supporting either mechanism exist in the literature. Here, we discuss potential mechanisms of transformation and review the current knowledge about cell of origin of NSCLC and SCLC. In addition, we summarize genomic alterations that are frequently observed in both "De novo" and transformed SCLC, such as TP53, RB1 and PIK3CA. We also discuss treatment options for transformed SCLC, including chemotherapy, radiotherapy, TKIs, immunotherapy and anti-angiogenic agents.

Making the Best Use of Available Weapons for the Inevitable Rivalry-Resistance to EGFR-TKIs

The emergence of epidermal growth factor receptor-tyrosine kinase inhibitors (EGFR-TKIs) revolutionized the treatment of advanced-stage non-small cell lung cancer (NSCLC). Detected in more than 50% of late-stage lung adenocarcinoma in Asian patients, the EGFR mutation was regarded as a golden mutation for Asians. However, resistance to TKIs seems inevitable and severely hinders patients from getting further benefits from treatment. Even though resistance caused by EGFR T790M could be effectively managed by third-generation EGFR-TKIs currently, resistance to third-generation EGFR-TKIs is still a troublesome issue faced by both clinicians and patients. Various efforts have been made to maximize the benefits of patients from EGFR-TKIs therapy. Thus, new requirements and challenges have been posed to clinicians of this era. In this review, we summarized the clinical evidence on the efficacy of third-generation EGFR-TKIs in patients with EGFR-mutated NSCLC. Then, we discussed advancements in sequential treatment aiming to delay the onset of resistance. Moreover, the resistance mechanisms and features were depicted to help us better understand our enemies. Lastly, we put forward future strategies, including recent approaches involving the utilization of antibody drug conjugates against resistance and research directions about shaping the evolution of NSCLC as a core idea in the management of NSCLC.

A Closer Look at EGFR Inhibitor Resistance in Non-Small Cell Lung Cancer through the Lens of Precision Medicine

The development of EGFR small-molecule inhibitors has provided significant benefit for the affected patient population. Unfortunately, current inhibitors are no curative therapy, and their development has been driven by on-target mutations that interfere with binding and thus inhibitory activity. Genomic studies have revealed that, in addition to these on-target mutations, there are also multiple off-target mechanisms of EGFR inhibitor resistance and novel therapeutics that can overcome these challenges are sought. Resistance to competitive 1st-generation and covalent 2nd- and 3rd-generation EGFR inhibitors is overall more complex than initially thought, and novel 4th-generation allosteric inhibitors are expected to suffer from a similar fate. Additional nongenetic mechanisms of resistance are significant and can include up to 50% of the escape pathways. These potential targets have gained recent interest and are usually not part of cancer panels that look for alterations in resistant patient specimen. We discuss the duality between genetic and nongenetic EGFR inhibitor drug resistance and summarize current team medicine approaches, wherein clinical developments, hand in hand with drug development research, drive potential opportunities for combination therapy.

Histomorphological transformation from non-small cell lung carcinoma to small cell lung carcinoma after targeted therapy or immunotherapy: A report of two cases

Molecular targeting and immunotherapy provide durable responses for advanced lung cancer clinical therapy in many patients. However, the mechanisms of occurrence of progressive disease and resistance to targeted therapy and immunotherapy have not been elucidated. Herein, we report two cases of small cell transformation of non-small cell lung cancer (NSCLC) after targeted therapy or immunotherapy. The first case was a 63-year-old female patient presenting with cough and expectoration. Left lung invasive adenocarcinoma was diagnosed after left lung tumor biopsy. After epidermal growth factor receptor-tyrosine kinase inhibitor (EGFR-TKI) targeted therapy for almost 2 years, disease progression and symptom aggravation were observed. Pathological and immunohistochemical staining results after biopsy revealed small cell lung cancer (SCLC). The second case was a 75-year-old male patient diagnosed with stage IV squamous cell carcinoma of the lung, who received carboplatin/paclitaxel adjuvant chemotherapy and pembrolizumab treatment with partial response. Disease progression and metastasis occurred within 15 cycles of immunotherapy. Computed tomography revealed a lower left lung tumor. Cytological examination of lung lavage fluid and biopsy under thoracoscope revealed SCLC. In conclusion, histological transformation to SCLC is a potential mechanism of NSCLC resistance to targeted therapy or immunotherapy. During treatment, clinicians should monitor serum tumor markers or genome sequencing, particularly in patients with disease progression, as this may be beneficial for early detection of SCLC transformation. Repeated biopsy can be performed if necessary, and the therapeutic regimen can be adjusted in a timely manner according to the results of molecular pathological tests for personalization and whole-process management.

Durable response to afatinib rechallenge in a long-term survivor of non-small cell lung cancer harboring EGFR L858R and L747V mutations

Epidermal growth factor receptor (EGFR)-tyrosine kinase inhibitors are standard therapeutic agents for non-small cell lung cancer (NSCLC) patients with major EGFR mutations such as exon 19 deletions and a L858R mutation, whereas treatment strategies for cases with uncommon EGFR mutations remain to be fully established. Here, we report a long-term (≥20 years from initial diagnosis) NSCLC survivor carrying EGFR L858R and L747V mutations. The patient received gefitinib monotherapy, systemic chemotherapy/chemoimmunotherapy, and local consolidative therapies for oligometastatic lesions, and responded to afatinib rechallenge with a progression-free survival of 12 months. The current case suggests that afatinib is effective in NSCLC patients with EGFR L858R and L747V mutations and that a therapeutic approach combining appropriately timed systemic therapies with local consolidative therapies for oligometastatic lesions improves long-term survival.