DLL3-guided therapies in small-cell lung cancer: from antibody-drug conjugate to precision immunotherapy and radioimmunotherapy.

DLL3 acts as an inhibitory ligand that downregulates Notch signaling and is upregulated by ASCL1, a transcription factor prevalent in the small-cell lung cancer (SCLC) subtype SCLC-A. Currently, the therapeutic strategies targeting DLL3 are varied, including antibody-drug conjugates (ADCs), bispecific T-cell engagers (BiTEs), and chimeric antigen receptor (CAR) T-cell therapies. Although rovalpituzumab tesirine (Rova-T) showed promise in a phase II study, it failed to produce favorable results in subsequent phase III trials, leading to the cessation of its development. Conversely, DLL3-targeted BiTEs have garnered significant clinical interest. Tarlatamab, for instance, demonstrated enhanced response rates and progression-free survival compared to the standard of care in a phase II trial; its biologics license application (BLA) is currently under US Food and Drug Administration (FDA) review. Numerous ongoing phase III studies aim to further evaluate tarlatamab's clinical efficacy, alongside the development of novel DLL3-targeted T-cell engagers, both bispecific and trispecific. CAR-T cell therapies targeting DLL3 have recently emerged and are undergoing various preclinical and early-phase clinical studies. Additionally, preclinical studies have shown promising efficacy for DLL3-targeted radiotherapy, which employs ß-particle-emitting therapeutic radioisotopes conjugated to DLL3-targeting antibodies. DLL3-targeted therapies hold substantial potential for SCLC management. Future clinical trials will be crucial for comparing treatment outcomes among various approaches and exploring combination therapies to improve patient survival outcomes.

Prophylactic Cranial Irradiation in Limited-Stage Small Cell Lung Cancer: A Meta-Analysis.

The role of prophylactic cranial irradiation (PCI) in limited-stage small cell lung cancer (LS-SCLC) has been questioned in the era of magnetic resonance imaging (MRI). The purpose of this study was to re-evaluate the efficacy of PCI in patients with LS-SCLC. Three electronic databases were searched, including PubMed, Embase, and the Cochrane Library from January 2012 to April 2022. All relevant publications were included based on the inclusion criteria, and survival data and brain metastasis (BM) rates were extracted and pooled. Ten studies were selected which involved 532 patients who received PCI and 613 patients who did not receive PCI. In pooled estimates, PCI significantly improved overall survival (OS) and progression-free survival (PFS) [hazard ratio (HR) = 0.71, 95% confidence interval (CI): 0.61-0.82, p <0.001; HR = 0.68, 95% CI: 0.48-0.97, p = 0.03, respectively]. Additionally, the use of PCI was associated with a significant reduction in the risk of brain metastasis (BM, risk ratio = 0.64, 95% CI: 0.46-0.90, p = 0.009). In subgroup analyses. The authors found that the PCI effects on OS were independent of region and the use of brain imaging after initial treatment. These findings demonstrate that PCI improves OS and PFS while decreasing the risk of BM in patients with LS-SCLC, implying that PCI remains necessary even in the MRI era. Key Words: Prophylactic cranial irradiation, Small cell lung cancer, Magnetic resonance imaging, Brain metastasis.

The therapeutic effect of radiotherapy combined with systemic therapy compared to radiotherapy alone in patients with simple brain metastasis after first-line treatment of limited-stage small cell lung cancer: a retrospective study.

PURPOSE: We aimed to compare the therapeutic effect of radiotherapy (RT) plus systemic therapy (ST) with RT alone in patients with simple brain metastasis (BM) after first-line treatment of limited-stage small cell lung cancer (LS-SCLC). METHODS: The patients were treated at a single center from January 2011 to January 2022. BM only without metastases to other organs was defined as simple BM. The eligible patients were divided into RT alone (monotherapy arm) and RT plus ST (combined therapy arm). Univariate and multivariate Cox proportional hazards analyses were used to examine factors associated with increased risk of extracranial progression. After 1:1 propensity score matching analysis, two groups were compared for extracranial progression-free survival (ePFS), PFS, overall survival (OS), and intracranial PFS (iPFS). RESULTS: 133 patients were identified and 100 were analyzed (monotherapy arm: n = 50, combined therapy arm: n = 50). The ePFS of the combined therapy was significantly longer than that of the monotherapy, with a median ePFS of 13.2 months (95% CI, 6.6-19.8) in combined therapy and 8.2 months (95% CI, 5.7-10.7) in monotherapy (P = 0.04). There were no statistically significant differences in PFS (P = 0.057), OS (P = 0.309), or iPFS (P = 0.448). Multifactorial analysis showed that combined therapy was independently associated with better ePFS compared with monotherapy (HR = 0.617, P = 0.034); more than 5 BMs were associated with worse ePFS compared with 1-5 BMs (HR = 1.808, P = 0.012). CONCLUSIONS: Compared with RT alone, combined therapy improves ePFS in patients with simple BM after first-line treatment of LS-SCLC. Combined therapy and 1-5 BMs reduce the risk of extracranial recurrence.

Six versus four or five cycles of first-line etoposide and platinum-based chemotherapy combined with thoracic radiotherapy in patients with limited-stage small-cell lung cancer: A propensity score-matched analysis of a prospective randomized trial.

OBJECTIVES: The recommended treatment for limited-stage small-cell lung cancer (LS-SCLC) is a combination of thoracic radiotherapy (TRT) and etoposide plus cisplatin (EP) chemotherapy, typically administered over 4-6 cycles. Nonetheless, the optimal duration of chemotherapy is still not determined. This study aimed to compare the outcomes of patients with LS-SCLC who received either 6 cycles or 4-5 cycles of EP chemotherapy combined with TRT. MATERIALS AND METHODS: In this retrospective analysis, we utilized data from our prior prospective trial to analyze the outcomes of 265 LS-SCLC patients who received 4-6 courses of EP combined with concurrent accelerated hyperfractionated TRT between 2002 and 2017. Patients were categorized into two groups depending on their number of chemotherapy cycles: 6 or 4-5 cycles. To assess overall survival (OS) and progression-free survival (PFS), we employed the Kaplan-Meier method after conducting propensity score matching (PSM). RESULTS: Among the 265 LS-SCLC patients, 60 (22.6%) received 6 cycles of EP chemotherapy, while 205 (77.4%) underwent 4-5 cycles. Following PSM (53 patients for each group), the patients in the 6 cycles group exhibited a significant improvement in OS and PFS in comparison to those in the 4-5 cycles group [median OS: 29.8 months (95% confidence interval [CI], 23.6-53.1 months) vs. 22.7 months (95% CI, 20.8-29.1 months), respectively, p = 0.019; median PFS: 17.9 months (95% CI, 13.7-30.5 months) vs. 12.0 months (95% CI, 9.8-14.2 months), respectively, p = 0.006]. The two-year and five-year OS rates were 60.38% and 29.87% in the 6 cycles group, whereas 47.17% and 15.72% in the 4-5 cycles group, respectively. CONCLUSION: Patients diagnosed with LS-SCLC who were treated with EP regimen chemotherapy combined with TRT exhibited notably enhanced survival when administered 6 cycles of chemotherapy, as compared to those who underwent only 4-5 cycles.

PD-L1 inhibitors combined with whole brain radiotherapy in patients with small cell lung cancer brain metastases: Real-world evidence.

BACKGROUND: Numerous studies have demonstrated that brain metastases patients may benefit from intracranial radiotherapy combined with immune checkpoint inhibitors (ICIs). However, it is unclear whether this treatment is effective for patients with small cell lung cancer brain metastases (SCLC-BMs). METHODS: We conducted a retrospective study by analyzing medical records of patients with SCLC-BMs from January 1, 2017 to June 1, 2022. Data related to median overall survival (mOS), median progression-free survival (mPFS), and intracranial progression-free survival (iPFS) were analyzed. RESULTS: A total of 109 patients were enrolled, of which 60 received WBRT and 49 received WBRT-ICI. Compared to the WBRT alone cohort, the WBRT-ICI cohort showed longer mOS (20.4 months vs. 29.3 months, p = 0.021), mPFS (7.9 months vs. 15.1 months, p < 0.001), and iPFS (8.3 months vs. 16.5 months, p < 0.001). Furthermore, WBRT-ICI cohort had a better response rate for both BMs. (p = 0.035) and extracranial diseases (p < 0.001) compared to those receiving WBRT alone. Notably, the use of WBRT before ICI was associated with longer mOS compared to the use of WBRT after ICI (23.3 months for the ICI-WBRT group vs. 34.8 months for the WBRT-ICI group, p = 0.020). CONCLUSION: Our results indicated that WBRT combined with immunotherapy improved survival in SCLC-BMs patients compared to WBRT monotherapy. Administering WBRT prior to ICI treatment is associated with improved survival outcomes compared to WBRT following ICI treatment, for patients with SCLC-BMs. These findings highlight the significance of conducting further prospective researches on combination strategies of intracranial radiotherapy and ICI in SCLC-BMs patients.

Long-term outcomes of intensity-modulated radiotherapy in limited-stage small-cell lung cancer classified according to AJCC 8th tumor node metastasis staging system.

OBJECTIVE: The objective of this study was to assess treatment outcomes of intensity-modulated radiotherapy with concomitant chemotherapy and to identify prognostic factors on survival in patients with limited-stage small-cell lung cancer. PATIENTS AND METHODS: A retrospective analysis was conducted on a cohort of seventy-two patients who received curative treatment between December 2011 and January 2023. Several clinical and biochemical parameters were examined as potential prognostic factors. RESULTS: The median age was 63 years, and 79% of them were males. Concomitant chemotherapy was administered in 83% of patients. Prophylactic cranial irradiation was applied in 61% of the cohort. Two and five-year overall survival (OS), disease-free survival (DFS), and local relapse-free survival (LRFS) rates were 50% and 25%, 38% and 24%, and 44% and 25%, respectively. Univariate analysis revealed that older age, comorbid lung disease, advanced tumor-node-metastasis (TNM) stage, radiotherapy (RT) alone, and the absence of prophylactic cranial irradiation (PCI) were adverse factors affecting OS. The advanced TNM stage emerged as a significant prognostic factor for LRFS and DFS, with a notable trend toward affecting OS. CONCLUSIONS: The TNM staging system is of significance in cases classified as limited-stage small-cell lung cancer due to its prognostic implications. Our results suggest that patients with more advanced TNM stage exhibit less favorable treatment outcomes, which may require individual tailoring of new systemic therapies.

Phase III, multicenter, randomized trial of 45 Gy versus 30 Gy thoracic radiation for extensive-stage small cell lung cancer (ES-SCLC): Study protocol.

BACKGROUND: Consolidative thoracic radiotherapy (cTRT) has previously shown benefit to patients with extensive stage small cell lung cancer (ES-SCLC) who respond to chemotherapy. However, the optimum dose of cTRT is unknown. The purpose of this randomized trial is to compare the efficacy of 45 Gy in 15 fractions with 30 Gy in 10 fractions cTRT in ES-SCLC. METHODS: This phase III, multicenter, randomized trial is designed to evaluate the safety and efficacy of different cTRT dose in ES-SCLC. Eligible patients with pathologically confirmed ES-SCLC who responded to 4-6 cycles of etoposide plus cisplatin (EP) or carboplatin (EC) chemotherapy were randomized 1:1 to receive either 30 Gy in 10 fractions (standard dose) or 45 Gy in 15 fractions (high dose) cTRT. The primary endpoint is 2-year overall survival (OS). Secondary endpoints include 2-year progression-free survival (PFS), 2-year local control (LC) and treatment related toxicity as measured by adverse events according to the Common Terminology Criteria for Adverse Events (version 4.0). DISCUSSION: The present study is the first randomized phase III trial designed to evaluate the efficacy of higher versus lower dose cTRT in ES-SCLC, providing evidence for future clinical practice in prolonging survival of patients with ES-SCLC.

Predicting overall survival and prophylactic cranial irradiation benefit in small-cell lung cancer with CT-based deep learning: A retrospective multicenter study.

BACKGROUND AND PURPOSE: To develop a computed tomography (CT)-based deep learning model to predict overall survival (OS) among small-cell lung cancer (SCLC) patients and identify patients who could benefit from prophylactic cranial irradiation (PCI) based on OS signature risk stratification. MATERIALS AND METHODS: This study retrospectively included 556 SCLC patients from three medical centers. The training, internal validation, and external validation cohorts comprised 309, 133, and 114 patients, respectively. The OS signature was built using a unified fully connected neural network. A deep learning model was developed based on the OS signature. Clinical and combined models were developed and compared with a deep learning model. Additionally, the benefits of PCI were evaluated after stratification using an OS signature. RESULTS: Within the internal and external validation cohorts, the deep learning model (concordance index [C-index] 0.745, 0.733) was far superior to the clinical model (C-index: 0.635, 0.630) in predicting OS, but slightly worse than the combined model (C-index: 0.771, 0.770). Additionally, the deep learning model had excellent calibration, clinical usefulness, and improved accuracy in classifying survival outcomes. Remarkably, patients at high risk had a survival benefit from PCI in both the limited and extensive stages (all P < 0.05), whereas no significant association was observed in patients at low risk. CONCLUSIONS: The CT-based deep learning model exhibited promising performance in predicting the OS of SCLC patients. The OS signature may aid in individualized treatment planning to select patients who may benefit from PCI.

Efficacy and safety of thoracic radiotherapy in extensive-stage small-cell lung cancer patients receiving first-line immunotherapy plus chemotherapy: a propensity score matched multicentre retrospective analysis.

BACKGROUND: Platinum-etoposide chemotherapy combined with immune checkpoint inhibitors (ICIs) has been recommended as the first-line standard treatment for extensive-stage small-cell lung cancer (ES-SCLC). However, the effect of thoracic radiotherapy (TRT) on these patients is still unknown. This study aimed to evaluate the efficacy and safety of TRT for ES-SCLC patients who responded to first-line ICIs and chemotherapy (CHT). METHODS: Patients who received 4 to 6 cycles of ICIs and CHT as first-line therapy at three hospitals between 2018 and 2022 were included in the analysis. All patients were divided into two groups based on whether they received TRT as first-line treatment, and propensity score matching (PSM) was performed to ensure that the characteristics of two groups were well-balanced. The primary endpoints were overall survival (OS) and progression-free survival (PFS), and the secondary endpoint was toxic effects. RESULTS: A total of 276 patients were included, and the median follow-up time was 22.3 (range, 4.0-53.73) months. After PSM, 197 patients were further analysed, and 99 of whom received TRT. The baseline characteristics were well-balanced between patients in the TRT and non-TRT groups. There were significant differences in PFS between the TRT and non-TRT groups, with the median PFS of 10.76 and 7.63 months, respectively (P = 0.014). Significantly improved OS was observed in the TRT group (21.67 vs. 16.6 months, P = 0.009). In addition, the use of TRT was an independent prognostic factor for PFS and OS of ES-SCLC patients receiving ICIs plus CHT. In terms of safety, no significant increase of any grades adverse event (AE) (P = 0.874) and G3-4 AE (P = 0.909) was observed for patients receiving TRT. Radiation esophagitis, gastrointestinal and hematologic toxicities were the most common AEs in TRT group, which were tolerable. And high-dose radiotherapy was associated with higher incidence of pneumonitis. CONCLUSION: Addition of TRT showed significant survival benefits and well tolerability in ES-SCLC patients receiving platinum-etoposide CHT and ICIs, which could be a feasible first-line treatment strategy for ES-SCLC patients.

Evaluating CD133 as a Radiotheranostic Target in Small-Cell Lung Cancer.

Despite decades of work, small-cell lung cancer (SCLC) remains a frustratingly recalcitrant disease. Both diagnosis and treatment are challenges: low-dose computed tomography (the approved method used for lung cancer screening) is unable to reliably detect early SCLC, and the malignancy's 5 year survival rate stands at a paltry 7%. Clearly, the development of novel diagnostic and therapeutic tools for SCLC is an urgent, unmet need. CD133 is a transmembrane protein that is expressed at low levels in normal tissue but is overexpressed by a variety of tumors, including SCLC. We previously explored CD133 as a biomarker for a novel autoantibody-to-immunopositron emission tomography (PET) strategy for the diagnosis of SCLC, work that first suggested the promise of the antigen as a radiotheranostic target in the disease. Herein, we report the in vivo validation of a pair of CD133-targeted radioimmunoconjugates for the PET imaging and radioimmunotherapy of SCLC. To this end, [89Zr]Zr-DFO-αCD133 was first interrogated in a trio of advanced murine models of SCLC─i.e., orthotopic, metastatic, and patient-derived xenografts─with the PET probe consistently producing high activity concentrations (>%ID/g) in tumor lesions combined with low uptake in healthy tissues. Subsequently, a variant of αCD133 labeled with the ß-emitting radiometal 177Lu─[177Lu]Lu-DTPA-A″-CHX-αCD133─was synthesized and evaluated in a longitudinal therapy study in a subcutaneous xenograft model of SCLC, ultimately revealing that treatment with a dose of 9.6 MBq of the radioimmunoconjugate produced a significant increase in median survival compared to a control cohort. Taken together, these data establish CD133 as a viable target for the nuclear imaging and radiopharmaceutical therapy of SCLC.

Application of postoperative adjuvant radiotherapy in limited-stage small cell lung cancer: A systematic review and meta-analysis.

BACKGROUND AND PURPOSE: One of the most important treatments for small cell lung cancer (SCLC) is radiation therapy. Currently, the criteria for administering postoperative adjuvant radiotherapy (PORT) in SCLC remain uncertain. Therefore, we conducted a meta-analysis to investigate the influence of PORT on the prognosis of limited-stage SCLC (LS-SCLC). METHODS: We conducted a comprehensive search across three databases, PubMed, Embase, and the Cochrane Library. Data analysis involved utilizing both random-effects and fixed-effects models for pooling the results. A comparative analysis was performed to assess the prognostic outcomes of patients with LS-SCLC who did and did not undergo PORT. The primary outcome assessed was overall survival (OS), while the secondary outcome was disease-free survival (DFS). RESULTS: This analysis included 11 retrospective studies comprising 7694 eligible participants. Among the entire population of LS-SCLC patients, the OS was superior in those receiving PORT than in those not receiving it (hazard ratio [HR]: 0.79, 95 % confidence interval [CI]: 0.71-0.87; P < 0.0001). In pN0 stage LS-SCLC patients, PORT was associated with a detrimental effect on OS (HR: 1.22, 95 % CI: 1.04-1.43; P = 0.01). In pN1 stage LS-SCLC patients, additionally administering PORT did not provide a significant OS advantage as compared to not administering it (HR: 0.82, 95 % CI: 0.60-1.12; P = 0.21). In pN2 stage LS-SCLC patients, those receiving PORT demonstrated a significant improvement in OS (HR: 0.59; 95 % CI: 0.50-0.70; P < 0.0001) as compared to those not receiving it. Regarding DFS in LS-SCLC patients, the difference in the protective effect with and without the administration of PORT was less pronounced (HR: 0.76, 95 % CI: 0.58-1.00; P = 0.053). CONCLUSIONS: With respect to OS, PORT is not advisable in patients with pN0 or pN1 stage LS-SCLC but is highly recommended in pN2 stage LS-SCLC. Further research is warranted to confirm these findings.

Hyperfractionated Accelerated Radiotherapy Versus Stereotactic Body Radiotherapy in the Treatment of Limited-Stage Small Cell Lung Cancer: A Matched-Pair Analysis.

BACKGROUND: Concurrent chemoradiotherapy based on hyperfractionated accelerated radiotherapy (HART) is the first-line recommended regimen for the treatment of small-cell lung cancer (SCLC). However, Stereotactic Body Radiotherapy (SBRT) is also regarded as an effective treatment for limited-stage (LS) SCLC, and the efficacy and safety of HART versus SBRT stay controversial. METHODS: In this study, 188 LS-SCLC patients were retrospectively divided into two groups receiving chemotherapy combined with either HART or SBRT. In HART group, patients received 4500 cGy in 30 fractions, administered twice daily for 3 weeks. Whereas in the SBRT group, a total radiation dose of 4000-4500 cGy was delivered in 10 fractions over 2 weeks. Thirty-three pairs of patients were finally included for next analysis. RESULTS: The estimated objective response rates were 63.6 % (21/33) and 78.8 % (26/33) in HART group and SBRT group, respectively (P = 0.269). Furthermore, there was no significant difference between HART and SBRT groups in overall survival (26 months vs. 29 months, P = 0.362) and progression free survival (11 months vs. 15 months, P = 0.223). As for the adverse events, toxicity of both groups is similar and slight that no grade 4 event was observed. Grade 3 pneumonitis cases were all occurred in the HART group (9.1%, 3/33, P = 0.238), and grade 3 esophagitis cases were all occurred in the SBRT group (6.1%, 2/33, P = 0.492). CONCLUSION: Compared with HART, SBRT could be another effective treatment with satisfactory safety for the concurrent chemoradiotherapy in patients with LS-SCLC.

Intrathoracic Progression Is Still the Most Dominant Failure Pattern after First-Line Chemo-immunotherapy in Extensive-Stage Small-Cell Lung Cancer: Implications for Thoracic Radiotherapy.

PURPOSE: This study aimed to compare the failure patterns before and after the introduction of immunotherapy and to determine the role of thoracic radiotherapy (TRT) in extensive-stage small-cell lung cancer (ES-SCLC) treatment. MATERIALS AND METHODS: We retrospectively reviewed 294 patients with ES-SCLC, of which 62.2% underwent chemotherapy alone, 13.3% underwent chemotherapy followed by consolidative TRT (TRT group), and 24.5% underwent chemotherapy with immune checkpoint inhibitor (ICI group). We performed propensity-score matching (PSM) to compare each treatment group. RESULTS: The median follow-up duration was 10.4 months. At the first relapse, in the cohort showing objective response, the proportion of cases showing intrathoracic progression was significantly lower in the TRT group (37.8%) than in the chemotherapy-alone (77.2%, p < 0.001) and the ICI (60.3%, p=0.03) groups. Furthermore, in the subgroup analysis, TRT showed benefits related to intrathoracic progression-free survival (PFS) in comparison with ICI in patients with less than two involved extrathoracic sites (p=0.008) or without liver metastasis (p=0.02) or pleural metastasis (p=0.005) at diagnosis. After PSM, the TRT group showed significantly better intrathoracic PFS than both chemotherapy-alone and ICI groups (p < 0.001 and p=0.04, respectively), but showed no significant benefit in terms of PFS and overall survival in comparison with the ICI group (p=0.17 and p=0.31, respectively). CONCLUSION: In ES-SCLC, intrathoracic progression was the most dominant failure pattern after immunotherapy. In the era of chemoimmunotherapy, consolidative TRT can still be considered a useful treatment strategy for locoregional control.

The tyrosine kinase inhibitor nintedanib enhances the efficacy of 90 Y-labeled B5209B radioimmunotherapy targeting ROBO1 without increased toxicity in small-cell lung cancer xenograft mice.

BACKGROUND: Small cell lung cancer (SCLC) has a poor prognosis, and Roundabout homolog 1 (ROBO1) is frequently expressed in SCLC. ROBO1-targeted radioimmunotherapy (RIT) previously showed tumor shrinkage, but regrowth with fibroblast infiltration was observed. The fibroblasts would support tumor survival by secreting growth factors and cytokines. Inhibition of fibroblasts offers a candidate strategy for increasing RIT efficacy. Here, we evaluated the efficacy of combination therapy with 90 Y-labeled anti-ROBO1 antibody B5209B ( 90 Y-B5209B) and the tyrosine kinase inhibitor nintedanib in SCLC xenograft mice. METHODS: Subcutaneous NCI-H69 SCLC xenograft mice were divided into four groups: saline, nintedanib alone, RIT alone, and a combination of RIT with nintedanib (combination). A single dose of 7.4 MBq of 90 Y-B5209B was injected intravenously. Nintedanib was orally administered at a dose of 400 µg five times a week for 4 weeks. Tumor volumes and body weights were measured regularly. Tumor sections were stained with hematoxylin and eosin or Masson trichrome. RESULTS: All six tumors in the combination therapy group disappeared, and four tumors showed no regrowth. Although RIT alone induced similar tumor shrinkage, regrowth was observed. Prolonged survival in the combination therapy group was found compared with the other groups. Temporary body weight loss was observed in RIT and combination therapy. There is no difference in fibroblast infiltration between RIT alone and the combination. CONCLUSION: Nintedanib significantly enhanced the anti-tumor effects of RIT with the 90 Y-B5209B without an increase in toxicity. These findings encourage further research into the potential clinical application of combining RIT with nintedanib.

CRISPR Screen of Druggable Targets in Small Cell Lung Cancer Identified ATM Inhibitor (AZD1390) as a Radiosensitizer.

PURPOSE: Small cell lung cancer (SCLC) is an aggressive and lethal form of lung cancer and the overall 5-year survival (OS) for patients is a dismal 7%. Radiation therapy (RT) provides some benefit for selected patients with SCLC but could be improved with radiosensitizing agents. In this study, we identified novel radiosensitizers for SCLC by a CRISPR-Cas9 screen and evaluated the efficacy of ATM inhibitor AZD1390 as a radiosensitizer of SCLC. METHODS AND MATERIALS: We transduced the SCLC cell line SBC5 with a custom CRISPR sgRNA library focused on druggable gene targets and treated cells with RT. Cells collected at multiple timepoints were subjected to next-generation sequencing. We determined radiosensitization both in vitro with cell lines assessed by short-term viability and clonogenic assays, and in vivo mouse models by tumor growth delay. Pharmacodynamic effects of AZD1390 were quantified by ATM-Ser1981 phosphorylation, and RT-induced DNA damage by comet assay. RESULTS: Using a CRISPR dropout screen, we identified multiple radiosensitizing genes for SCLC at various timepoints with ATM as a top determinant gene for radiosensitivity. Validation by ATM knockout (KO) demonstrated increased radiosensitivity by short-term viability assay (dose modification factor [DMF]50 = 3.25-3.73 in SBC5 ATM-KO) and clonogenic assays (DMF37 1.25-1.65 in SBC5 ATM-KO). ATM inhibition by AZD1390 effectively abrogated ATM Ser1981 phosphorylation in SCLC cell lines and increased RT-induced DNA damage. AZD1390 synergistically increased the radiosensitivity of SCLC cell lines (cell viability assay: SBC5 DMF37 = 2.19, SHP77 DMF37 = 1.56, H446 DMF37 = 3.27, KP1 DMF37 = 1.65 at 100nM; clonogenic assay: SBC5 DMF37 = 4.23, H1048 DMF37 = 1.91), and in vivo murine syngeneic, KP1, and patient-derived xenograft (PDX) models, JHU-LX108 and JHU-LX33. CONCLUSIONS: In this study, we demonstrated that genetically and pharmacologically (AZD1390) inhibiting ATM markedly enhanced RT against SCLC, providing a novel pharmacologically tractable radiosensitizing strategy for patients with SCLC.

Effective Treatment of SSTR2-Positive Small Cell Lung Cancer Using 211At-Containing Targeted α-Particle Therapy Agent Which Promotes Endogenous Antitumor Immune Response.

Small cell lung cancer (SCLC) is a neuroendocrine tumor with a high degree of malignancy. Due to limited treatment options, patients with SCLC have a poor prognosis. We have found, however, that intravenously administered octreotide (Oct) armed with astatine-211 ([211At]SAB-Oct) is effective against a somatostatin receptor 2 (SSTR2)-positive SCLC tumor in SCLC tumor-bearing BALB/c nude mice. In biodistribution analysis, [211At]SAB-Oct achieved the highest concentration in the SCLC tumors up to 3 h after injection as time proceeded. A single intravenous injection of [211At]SAB-Oct (370 kBq) was sufficient to suppress SSTR2-positive SCLC tumor growth in treated mice by inducing DNA double-strand breaks. Additionally, a multitreatment course (370 kBq followed by twice doses of 370 kBq for a total of 1110 kBq) inhibited the growth of the tumor compared to the untreated control group without significant off-target toxicity. Surprisingly, we found that [211At]SAB-Oct could up-regulate the expressions of calreticulin and major histocompatibility complex I (MHC-I) on the tumor cell membrane surface, suggesting that α-particle internal irradiation may activate an endogenous antitumor immune response through the regulation of immune cells in the tumor microenvironment, which could synergically enhance the efficacy of immunotherapy. We conclude that [211At]SAB-Oct is a potential new therapeutic option for SSTR2-positive SCLC.

[Clinical study of antinib combined with radiotherapy in the treatment of third-line extensive small cell lung cancer].

Objective: To explore whether the survival benefit of the third-line extensive small-cell lung cancer (ES-SCLC) will be obtained by the combination of anlotinib and radiotherapy, and evaluate the safety of this treatment regimen. Methods: Twenty-seven patients with ES-SCLC who received third-line treatment with less than three metastatic organs at the Cancer Hospital of Xinjiang Medical University from November 2018 to July 2021 were collected and treated with radiotherapy based on anlotinib. Kaplan-Meier curve was used to estimate the overall survival (OS) and progression-free survival (PFS), descriptive statistical analysis was used to evaluate the safety, and European organisation for research and treatment of cancer quality of life questionnaire-core 30 (EORTC QLQ-C30) was used to evaluate the quality of life. Results: The follow-up cut-off date was July 1, 2021, and the follow-up time ranged from 4.8 to 31.0 months, with a median follow-up time of 10.2 months for the entire group. Among the 27 patients, 4 achieved partial remission, 17 had stable disease and 6 had progression of disease. The objective remission rate (ORR) was 14.8%, and the disease control rate (DCR) was 77.8%. Median PFS and the median OS were 5 months and 11 months, respectively. The most common adverse reactions included fatigue (33.3%, 9/27), anorexia (14.8%, 4/27), bleeding (14.8%, 4/27) and hand-foot syndrome (11.1%, 3/27). Most of them were grade 1 to grade 2, 3 cases were more than grade 3, and there was no grade 5 toxicity recorded. After radiotherapy combined with amlotinib treatment, patients showed improvement in general health, somatic functioning, social functioning, and emotional functioning (all P<0.05). Conclusion: For the third-line ES-SCLC patients, radiotherapy based on the anlotinib can significantly prolong their PFS and OS, and the adverse reactions can be tolerated.

Reduction of tumor volume during radiotherapy in patients with small-cell lung cancer and its prognostic significance.

BACKGROUND: Several studies have reported the potential prognostic significance of tumor volume reduction ratio (VRR) induced by radiotherapy (RT) in patients with non-small-cell lung cancer. However, there are no data yet on the prognostic significance of volumetric shrinkage in patients with small-cell lung cancer (SCLC). This study aimed to demonstrate the correlation between tumor volume reduction ratio and treatment outcomes. MATERIALS AND METHODS: The study included 61 patients with SCLC treated with fractionated RT of the primary tumor at our institution between 2013 and 2020. The relationship between volumetric changes in gross tumor volume (GTV) during radiotherapy and outcomes were analyzed and reported. RESULTS: The median radiation dose was 59.4 Gy (median fraction dose was 1.8 Gy). The median GTV before radiotherapy was 74 cm3, with a median GTV reduction of 48%. There was a higher VRR in patients receiving concurrent radiochemotherapy (p = 0.05). No volumetric parameters were identified as relevant predictors of outcome in the entire cohort. In multivariate analysis, only age had an impact on survival, while prophylactic whole-brain radiation influenced the progression-free survival significantly. CONCLUSION: Concurrent chemotherapy was associated with a higher VRR than sequential chemotherapy. No significant impact of VRR on patients' outcome or survival was detected.

Radiotherapy for extensive-stage small-cell lung cancer in the immunotherapy era.

Currently, chemoimmunotherapy is the first-line treatment for extensive-stage small-cell lung cancer (ES-SCLC). However, only 0.8%-2.5% of the patients presented complete response after chemoimmunotherapy. Considering that ES-SCLC is highly sensitive to radiotherapy, the addition of radiotherapy after first-line treatment for ES-SCLC could further improve local control, which may be beneficial for patients' survival. Prior studies have shown that consolidative thoracic radiotherapy (cTRT) can decrease disease progression and improve overall survival in patients with ES-SCLC who respond well to chemotherapy. However, the efficacy and safety of cTRT in the immunotherapy era remain unclear owing to a lack of prospective studies. Prophylactic cranial irradiation (PCI) has been shown to decrease brain metastasis (BM) and prolong survival in patients with limited-stage SCLC in previous reports. However, according to current guidelines, PCI is not commonly recommended for ES-SCLC. Immunotherapy has the potential to reduce the incidence of BM. Whether PCI can be replaced with regular magnetic resonance imaging surveillance for ES-SCLC in the era of immunotherapy remains controversial. Whole brain radiation therapy (WBRT) is the standard treatment for BM in SCLC patients. Stereotactic radiosurgery (SRS) has shown promise in the treatment of limited BM. Considering the potential of immunotherapy to decrease BM, it is controversial whether SRS can replace WBRT for limited BM in the immunotherapy era. Additionally, with the addition of immunotherapy, the role of palliative radiotherapy may be weakened in patients with asymptomatic metastatic lesions. However, it is still indispensable and urgent for patients with obvious symptoms of metastatic disease, such as spinal cord compression, superior vena cava syndrome, lobar obstruction, and weight-bearing metastases, which may critically damage the quality of life and prognosis. To improve the outcome of ES-SCLC, we discuss the feasibility of radiotherapy, including cTRT, PCI, WBRT/SRS, and palliative radiotherapy with immunotherapy based on existing evidence, which may offer specific prospects for further randomized trials and clinical applications.

The incorporation of cognitive-sparing techniques into prophylactic cranial irradiation in the management of small cell lung cancer.

The use of prophylactic cranial irradiation (PCI) remains an important component in the management of small cell lung cancer (SCLC). This is due to the high rates of subclinical brain metastases at the time of diagnosis. Following a response to initial treatment, PCI historically has been associated with improvements in overall survival and decreased development of brain metastases in patients with limited stage (LS-SCLC) and extensive stage (ES-SCLC) SCLC. However, PCI is commonly withheld in these settings in favor of observation, largely due to its association with cognitive sequelae following treatment. While randomized data has demonstrated that in patients with ES-SCLC, PCI may be withheld in favor of close MRI surveillance without a detriment in overall survival or cognitive functioning, these patients did not undergo formal neuropsychological assessments. In recent years, cognitive sparing techniques incorporated into whole brain radiation therapy and PCI, such as the addition of memantine and hippocampal avoidance, have demonstrated significant improvements in cognitive outcomes. As the overall survival in patients with SCLC continues to improve due to the incorporation of novel systemic therapies (e.g., immune checkpoint inhibitors), the role of PCI and maximizing quality of life remains a highly relevant topic. This article reviews the role of PCI and cognitive-sparing techniques in the management of SCLC.