Virtual Library
Start Your Search
Benjamin H Lok
Author of
-
+
MA05 - Improving Outcomes in Locoregional NSCLC II (ID 901)
- Event: WCLC 2018
- Type: Mini Oral Abstract Session
- Track: Treatment of Locoregional Disease - NSCLC
- Presentations: 1
- Moderators:
- Coordinates: 9/24/2018, 13:30 - 15:00, Room 105
-
+
MA05.08 - Discussant - MA 05.05, MA 05.06, MA 05.07 (ID 14591)
14:15 - 14:30 | Presenting Author(s): Benjamin H Lok
- Abstract
- Presentation
Abstract not provided
Only Members that have purchased this event or have registered via an access code will be able to view this content. To view this presentation, please login, select "Add to Cart" and proceed to checkout. If you would like to become a member of IASLC, please click here.
-
+
MA22 - New Therapeutics, Pathology, and Brain Metastases for Small Cell and Neuroendocrine Tumour (ID 925)
- Event: WCLC 2018
- Type: Mini Oral Abstract Session
- Track: Small Cell Lung Cancer/NET
- Presentations: 1
- Moderators:
- Coordinates: 9/25/2018, 15:15 - 16:45, Room 206 BD
-
+
MA22.01 - PARP Inhibitor Radiosensitization of Small Cell Lung Cancer Differs by PARP Trapping Potency (ID 13358)
15:15 - 15:20 | Presenting Author(s): Benjamin H Lok
- Abstract
- Presentation
Background
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.
a9ded1e5ce5d75814730bb4caaf49419 Method
Short-term viability assays and clonogenic survival assays (CSA) were used to assess radiosensitization in six SCLC cell lines. Doses of veliparib and talazoparib with equivalent enzymatic inhibitory activity but differing PARP trapping activity were identified and compared in CSAs. The dose modification factor (DMF), defined as the ratio of RT dose needed to achieve an equivalent level of survival with RT alone compared to that for RT plus drug, was calculated at 37% survival. Phosphorylated gH2AX sub-nuclear foci were assessed by immunofluorescence to quantify double-stranded DNA breaks (DSBs). Talazoparib, IR, and their combination were tested in three patient-derived xenograft (PDX) models.
4c3880bb027f159e801041b1021e88e8 Result
Talazoparib radiosensitized 5 of 6 SCLC cell lines in short-term viability assays with a talazoparib dose of 20 nM demonstrating a DMF ranging from 1.61 – 2.88 in 4 cell lines with 0.2 nM demonstrating a DMF of 1.56 in 1 additional cell line. We confirmed radiosensitization in 3 of 3 cell lines by CSAs with DMF ranging from 1.40 – 2.20. To determine effects of PARP trapping on radiosensitization, we identified that concentrations of 200 nM talazoparib and 1600 nM veliparib similarly inhibited PAR polymerization; however, talazoparib exhibited greater PARP trapping activity that was associated with superior radiosensitization (DMF 3.3 with talazoparib vs DMF 1.0 with veliparib). This observation further correlated with an increased number of DSBs induced by talazoparib as compared to veliparib, where we found that talazoparib produced more residual DSBs than veliparib and DMSO with IR (gH2AX foci mean per cell: talazoparib 53.5, veliparib 33.5, DMSO 25.5) and without IR (40.0, 19.6, 14.6). 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.
8eea62084ca7e541d918e823422bd82e Conclusion
PARP inhibition effectively sensitizes SCLC cell lines and PDXs to RT, 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 RT in SCLC.
6f8b794f3246b0c1e1780bb4d4d5dc53Only Members that have purchased this event or have registered via an access code will be able to view this content. To view this presentation, please login, select "Add to Cart" and proceed to checkout. If you would like to become a member of IASLC, please click here.
-
+
MA25 - Oligometastasis: Defining, Treating, and Evaluating (ID 929)
- Event: WCLC 2018
- Type: Mini Oral Abstract Session
- Track: Oligometastatic NSCLC
- Presentations: 1
- Moderators:
- Coordinates: 9/26/2018, 13:30 - 15:00, Room 203 BD
-
+
MA25.11 - Clinical and Molecular Predictors of Outcome in Patients with EGFR mutant NSCLC Brain Metastases treated with RT (ID 14529)
14:40 - 14:45 | Author(s): Benjamin H Lok
- Abstract
- Presentation
Background
Brain metastases(BM) develop in ~45% of patients with EGFR mutant(EGFRm) non-small cell lung cancers(NSCLC). There are limited reports on clinical/molecular factors associated with BM outcomes after radiotherapy in EGFRm NSCLC patients.
a9ded1e5ce5d75814730bb4caaf49419 Method
We identified patients with EGFRm NSCLC who presented with or developed BM and had their lung tumor resected. Clinical, demographic and TP53 status were collected from medical/pathology records. Whole-Exome Sequencing of the primary tumor was performed. Overall survival(OS) and intracranial progression(IP) were defined from start of BM treatment and correlated with clinical/molecular features. IP was defined from the date of BM treatment until any brain failure, either local(previously present BM) or distant(development of new BM). Categorical and continuous covariates were tested by Fisher exact or Mann-Whitney test, respectively. OS by Kaplan-Meier with groups compared by log-rank. For each model the Harrell Concordance Index(CI) was performed.
4c3880bb027f159e801041b1021e88e8 Result
From 41 eligible patients with BM, 9 were excluded due to sequencing quality. Of the 32 remaining patients, 20 (62%) had their BM treated with WBI (15 WBI alone and 5 TKIàWBI), 12 (38%) with TKI±SRS (9 TKI àSRS; 2 TKI alone and 1 SRS alone). Median age at BM was 59.5 years(y). Most of the cohort were female(81%), non-smoker(78%), non-Asian(62%) and 50% presented as stage III or higher at diagnosis. An EGFR exon 19 mutation was present in 72% of patients, 25% had 2 or more EGFRm, 15% with additional driver mutations and 53% with TP53 co-mutation. At a median follow-up of 1.21-y, no clinical/molecular factors(treatment, age, gender, ethnicity, smoking status, stage at presentation, EFGR exon 19 versus 21, number of EGFRm, additional driver mutations, TP53 co-mutation) correlated with survival. There was a trend for longer survival for patients treated with TKI±SRS(median 3.4y) compared to WBRT±TKI(median 1.4y); p=0.08 and for age at BM ≤59.5y(median 2.5y) compared to >59.5y (median 1.4y); p=0.2. Higher risk of IP was observed in younger patients (age as continuous variable) with HR of 0.94(95%CI 0.88-1.0), p=0.04; favoring older patients and remained significant after accounting for treatment modality on multivariate analysis p=0.03. No additional clinical/molecular factors correlated with IP.
8eea62084ca7e541d918e823422bd82e Conclusion
In our study, younger age at BM treatment was associated with higher IP. We also observed a trend for longer OS for younger patients(≤59.5y) and for patients treated with TKI±SRS. Our data suggest that younger patients with EGFR BM should undergo close intracranial follow up and that future studies to define the benefit of brain-directed multimodality treatment are warranted.
6f8b794f3246b0c1e1780bb4d4d5dc53Only Members that have purchased this event or have registered via an access code will be able to view this content. To view this presentation, please login, select "Add to Cart" and proceed to checkout. If you would like to become a member of IASLC, please click here.
