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Purpose: Small cell lung cancer (SCLC) is an exceptionally lethal form of lung cancer with limited treatment options. Delta-like ligand 3 (DLL3) is an attractive therapeutic target as surface expression is almost exclusive to tumor cells., Experimental Design: We radiolabeled the anti-DLL3 mAb SC16 with the therapeutic radioisotope, Lutetium-177. [177Lu]Lu-DTPA-CHX-A"-SC16 binds to DLL3 on SCLC cells and delivers targeted radiotherapy while minimizing radiation to healthy tissue., Results: [177Lu]Lu-DTPA-CHX-A"-SC16 demonstrated high tumor uptake with DLL3-target specificity in tumor xenografts. Dosimetry analyses of biodistribution studies suggested that the blood and liver were most at risk for toxicity from treatment with high doses of [177Lu]Lu-DTPA-CHX-A"-SC16. In the radioresistant NCI-H82 model, survival studies showed that 500 μCi and 750 μCi doses of [177Lu]Lu-DTPA-CHX-A"-SC16 led to prolonged survival over controls, and 3 of the 8 mice that received high doses of [177Lu]Lu-DTPA-CHX-A"-SC16 had pathologically confirmed complete responses (CR). In the patient-derived xenograft model Lu149, all doses of [177Lu]Lu-DTPA-CHX-A"-SC16 markedly prolonged survival. At the 250 μCi and 500 μCi doses, 5 of 10 and 7 of 9 mice demonstrated pathologically confirmed CRs, respectively. Four of 10 mice that received 750 μCi of [177Lu]Lu-DTPA-CHX-A"-SC16 demonstrated petechiae severe enough to warrant euthanasia, but the remaining 6 mice demonstrated pathologically confirmed CRs. IHC on residual tissues from partial responses confirmed retained DLL3 expression. Hematologic toxicity was dose-dependent and transient, with full recovery within 4 weeks. Hepatotoxicity was not observed., Conclusions: Together, the compelling antitumor efficacy, pathologic CRs, and mild and transient toxicity profile demonstrate strong potential for clinical translation of [177Lu]Lu-DTPA-CHX-A"-SC16., (©2022 American Association for Cancer Research.)

Purpose: Patients with SCLC rarely undergo biopsies at relapse. When pursued, tissue obtained can be inadequate for molecular testing, posing a challenge in identifying potentially targetable alterations in a clinically meaningful time frame. We examined the feasibility of circulating tumor DNA (ctDNA) testing in identifying potentially targetable alterations in SCLC., Experimental Design: ctDNA test results were prospectively collected from patients with SCLC between 2014 and 2017 and analyzed. ctDNA profiles of SCLC at diagnosis and relapse were also compared., Results: A total of 609 samples collected from 564 patients between 2014 and 2017 were analyzed. The median turnaround time for test results was 14 days. Among patients with data on treatment status, there were 61 samples from 59 patients and 219 samples from 206 patients collected at diagnosis and relapse, respectively. The number of mutations or amplifications detected per sample did not differ by treatment status. Potentially targetable alterations in DNA repair, MAPK and PI3K pathways, and genes such as MYC and ARID1A were identifiable through ctDNA testing. Furthermore, our results support that it may be possible to reconstruct the clonal relationship between detected variants through ctDNA testing., Conclusions: Patients with relapsed SCLC rarely undergo biopsies for molecular testing and often require prompt treatment initiation. ctDNA testing is less invasive and capable of identifying alterations in relapsed disease in a clinically meaningful timeframe. ctDNA testing on an expanded gene panel has the potential to advance our knowledge of the mechanisms underlying treatment resistance in SCLC and aid in the development of novel treatment strategies., (©2019 American Association for Cancer Research.)

Purpose: Small cell lung cancer (SCLC) is an aggressive malignancy with a critical need for novel therapies. Our goal was to determine whether PARP inhibition could sensitize SCLC cells to ionizing radiation (IR) and if so, to determine the contribution of PARP trapping to radiosensitization. Experimental Design: Short-term viability assays and clonogenic survival assays (CSA) were used to assess radiosensitization in 6 SCLC cell lines. Doses of veliparib and talazoparib with equivalent enzymatic inhibitory activity but differing PARP trapping activity were identified and compared in CSAs. Talazoparib, IR, and their combination were tested in three patient-derived xenograft (PDX) models. Results: Talazoparib radiosensitized 5 of 6 SCLC cell lines in short-term viability assays and confirmed in 3 of 3 cell lines by CSAs. Concentrations of 200 nmol/L talazoparib and 1,600 nmol/L veliparib similarly inhibited PAR polymerization; however, talazoparib exhibited greater PARP trapping activity that was associated with superior radiosensitization. This observation further correlated with an increased number of double-stranded DNA breaks induced by talazoparib as compared with veliparib. Finally, a dose of 0.2 mg/kg talazoparib in vivo caused tumor growth inhibition in combination with IR but not as a single agent in 3 SCLC PDX models. Conclusions: PARP inhibition effectively sensitizes SCLC cell lines and PDXs to IR, and PARP trapping activity enhances this effect. PARP inhibitors, especially those with high PARP trapping activity, may provide a powerful tool to improve the efficacy of radiotherapy in SCLC. Clin Cancer Res; 24(20); 5143-52. ©2018 AACR ., (©2018 American Association for Cancer Research.)

Purpose: PARP inhibitors (PARPi) are a novel class of small molecule therapeutics for small cell lung cancer (SCLC). Identification of predictors of response would advance our understanding, and guide clinical application, of this therapeutic strategy., Experimental Design: Efficacy of PARP inhibitors olaparib, rucaparib, and veliparib, as well as etoposide and cisplatin in SCLC cell lines, and gene expression correlates, was analyzed using public datasets. HRD genomic scar scores were calculated from Affymetrix SNP 6.0 arrays. In vitro talazoparib efficacy was measured by cell viability assays. For functional studies, CRISPR/Cas9 and shRNA were used for genomic editing and transcript knockdown, respectively. Protein levels were assessed by immunoblotting and immunohistochemistry (IHC). Quantitative synergy of talazoparib and temozolomide was determined in vitro In vivo efficacy of talazoparib, temozolomide, and the combination was assessed in patient-derived xenograft (PDX) models., Results: We identified SLFN11, but not HRD genomic scars, as a consistent correlate of response to all three PARPi assessed, with loss of SLFN11 conferring resistance to PARPi. We confirmed these findings in vivo across multiple PDX and defined IHC staining for SLFN11 as a predictor of talazoparib response. As temozolomide has activity in SCLC, we investigated combination therapy with talazoparib and found marked synergy in vitro and efficacy in vivo, which did not solely depend on SLFN11 or MGMT status., Conclusions: SLFN11 is a relevant predictive biomarker of sensitivity to PARP inhibitor monotherapy in SCLC and we identify combinatorial therapy with TMZ as a particularly promising therapeutic strategy that warrants further clinical investigation. Clin Cancer Res; 23(2); 523-35. ©2016 AACR., Competing Interests: The authors have no conflicts of interest to disclose., (©2016 American Association for Cancer Research.)

Purpose: Pulmonary large cell neuroendocrine carcinoma (LCNEC) is a highly aggressive neoplasm, whose biologic relationship to small cell lung carcinoma (SCLC) versus non-SCLC (NSCLC) remains unclear, contributing to uncertainty regarding optimal clinical management. To clarify these relationships, we analyzed genomic alterations in LCNEC compared with other major lung carcinoma types., Experimental Design: LCNEC (n = 45) tumor/normal pairs underwent targeted next-generation sequencing of 241 cancer genes by Memorial Sloan Kettering-Integrated Mutation Profiling of Actionable Cancer Targets (MSK-IMPACT) platform and comprehensive histologic, immunohistochemical, and clinical analysis. Genomic data were compared with MSK-IMPACT analysis of other lung carcinoma histologies (n = 242)., Results: Commonly altered genes in LCNEC included TP53 (78%), RB1 (38%), STK11 (33%), KEAP1 (31%), and KRAS (22%). Genomic profiles segregated LCNEC into 2 major and 1 minor subsets: SCLC-like (n = 18), characterized by TP53+RB1 co-mutation/loss and other SCLC-type alterations, including MYCL amplification; NSCLC-like (n = 25), characterized by the lack of coaltered TP53+RB1 and nearly universal occurrence of NSCLC-type mutations (STK11, KRAS, and KEAP1); and carcinoid-like (n = 2), characterized by MEN1 mutations and low mutation burden. SCLC-like and NSCLC-like subsets revealed several clinicopathologic differences, including higher proliferative activity in SCLC-like tumors (P < 0.0001) and exclusive adenocarcinoma-type differentiation marker expression in NSCLC-like tumors (P = 0.005). While exhibiting predominant similarity with lung adenocarcinoma, NSCLC-like LCNEC harbored several distinctive genomic alterations, including more frequent mutations in NOTCH family genes (28%), implicated as key regulators of neuroendocrine differentiation., Conclusions: LCNEC is a biologically heterogeneous group of tumors, comprising distinct subsets with genomic signatures of SCLC, NSCLC (predominantly adenocarcinoma), and rarely, highly proliferative carcinoids. Recognition of these subsets may inform the classification and management of LCNEC patients. Clin Cancer Res; 22(14); 3618-29. ©2016 AACR., (©2016 American Association for Cancer Research.)

Purpose: Seneca Valley Virus (SVV-001) is a novel naturally occurring replication-competent picornavirus with potent and selective tropism for neuroendocrine cancer cell types, including small cell lung cancer. We conducted a first-in-human, first-in-class phase I clinical trial of this agent in patients with cancers with neuroendocrine features, including small cell lung cancer., Experimental Design: Clinical evaluation of single intravenous doses in patients with cancers with neuroendocrine features was performed across five log-increments from 10(7) to 10(11) vp/kg. Toxicity, viral titers and clearance, neutralizing antibody development, and tumor response were assessed., Results: A total of 30 patients were treated with SVV-001, including six with small cell carcinoma at the lowest dose of 10(7) vp/kg. SVV-001 was well tolerated, with no dose-limiting toxicities observed in any dose cohort. Viral clearance was documented in all subjects and correlated temporally with development of antiviral antibodies. Evidence of in vivo intratumoral viral replication was observed among patients with small cell carcinoma, with peak viral titers estimated to be >10(3)-fold higher than the administered dose. One patient with previously progressive chemorefractory small cell lung cancer remained progression-free for 10 months after SVV-001 administration, and is alive over 3 years after treatment., Conclusions: Intravenous SVV-001 administration in patients is well tolerated at doses up to 10(11) vp/kg, with predictable viral clearance kinetics, intratumoral viral replication, and evidence of antitumor activity in patients with small cell lung cancer. Phase II clinical evaluation in small cell lung cancer is warranted, and has been initiated., (©2011 AACR.)