Abstract 2899: Single-cell analyses reveal increasing intratumoral heterogeneity as an essential component of treatment resistance in small cell lung cancer

Small cell lung cancer (SCLC) is an aggressive malignancy characterized by rapid onset of platinum-resistance. However, mechanisms underlying platinum-resistance remain obscure due to scarcity of tissue samples from relapsed patients. We generated circulating tumor cell (CTC)-derived xenograft (CDX) models from SCLC patients that recapitulate patient tumor genomics and response to platinum chemotherapy. Little is known about whether intratumoral heterogeneity (ITH) exists in SCLC and how it may contribute to clinical outcomes and development of treatment resistance. To investigate this, we performed baseline single-cell RNAseq analyses of platinum-sensitive and -resistant CDX models, as well as longitudinal single-cell RNAseq analyses of CDX models and patient CTCs over the course of therapy. Within each CDX model, we observe not only increased ITH with resistance (variance-based metric, P=0.018), but distinct cellular populations with unique gene signatures associated with resistance (e.g. EMT, DNA damage repair, MYC activation, etc.). To confirm this relationship between ITH and resistance, platinum-sensitive CDX models were subjected to extended treatment with DNA damage response targeted therapies until relapse occurred. Single-cell RNAseq confirmed that, as predicted, untreated tumors were molecularly homogeneous, while relapse was associated with increased ITH and multiple, concurrent mechanisms of resistance, including TGF beta signaling and G2/M checkpoints. Unexpectedly, we found variations in the mechanisms of resistance within replicate treatment-relapsed mice, suggesting that resistance even to molecularly targeted therapies does not follow a predictable, reproducible pathway. For example, onset of resistance to a PARP inhibitor resulted in upregulation of NOTCH signaling in one tumor, but not others. Similarly, longitudinal single-cell profiling of CTCs directly from patient blood before, during, and after platinum-relapse confirmed increased ITH post-relapse accompanying unique mechanisms of resistance within specific cell populations (e.g., MYC activation, EMT, and TNFα signaling). We independently found ITH of protein expression (e.g., SLFN11, EZH2, EMT) in CTCs isolated from patient blood, signifying a method for measuring ITH clinically. These data suggest that treatment resistance in SCLC entails a fluid process of shifting expression profiles to generate an increasingly heterogeneous tumor with multiple, disparate mechanisms of resistance. Clinically, these findings imply that drug development efforts in this disease should focus on combination or maintenance therapies for treatment-naïve SCLC tumors to maximize depth of initial responses and delay the onset of resistance defined by ITH.

Citation Format: C. Allison Stewart, Carl M. Gay, Yuanxin Xi, Junya Fujimoto, Neda Kalhor, Patrice M. Hartsfield, Hai Tran, Luisa Fernandez, David Lu, Yipeng Wang, Ryan Dittamore, Jianjun Zhang, Stephen G. Swisher, Jack A. Roth, Trudy G. Oliver, John V. Heymach, Ignacio I. Wistuba, Bonnie S. Glisson, Paul Robson, Jing Wang, Lauren A. Byers. Single-cell analyses reveal increasing intratumoral heterogeneity as an essential component of treatment resistance in small cell lung cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 2899.

Circulating inflammation signature predicts overall survival and relapse-free survival in metastatic colorectal cancer

BACKGROUND

Metastatic colorectal cancer (mCRC) is a highly heterogeneous disease from a clinical, molecular, and immunological perspective. Current predictive models rely primarily in tissue based genetic analysis, which not always correlate with inflammatory response. Here we evaluated the role of a circulating inflammatory signature as a prognostic marker in mCRC.

METHODS

Two hundred eleven newly diagnosed patients with mCRC were enrolled in the study. One hundred twenty-one patients had unresectable metastases, whereas ninety patients had potentially resectable liver metastases at presentation. Analysis of miR-21, IL-6, and IL-8 in the plasma of peripheral blood was performed at baseline. Patients with high circulating levels of ≥2 of the three inflammation markers (miR-21, IL-6, and IL-8) were considered to have the "Inflammation phenotype-positive CISIG".

RESULTS

Positive CISIG was found in 39/90 (43%) and 50/121 (45%) patients in the resectable and unresectable cohort, respectively. In the resectable population the median relapse-free survival was 18.4 compared to 31.4 months (p = 0.001 HR 2.09, 95% CI 1.2-3.67) for positive vs. negative CISIG. In contrast, the individual components were not significant. In the same population the median overall survival was 46.2 compared to 66.0 months (p = 0.0003, HR 2.57, 95% CI 1.26-5.27) for positive vs. negative CISIG, but not significant for the individual components. In the unresectable population, the median overall survival was 13.5 compared to 25.0 months (p = 0.0008, HR 2.49, 95% CI 1.46-4.22) for positive vs. negative CISIG. IL-6 was independently prognostic with overall survival of 16.2 compared to 27.0 months (p = 0.004, HR 1.96, 95% CI 1.24-3.11) for high vs. low IL-6, but not the other components. Using a Cox regression model, we demonstrated that CISIG is an independent predictive marker of survival in patients with unresectable disease (HR 1.8, 95% CI 1.2, 2.8, p < 0.01).

CONCLUSION

In two different cohorts, we demonstrated that CISIG is a strong prognostic factor of relapse-free and overall survival of patients with mCRC. Based on these data, analysis of circulating inflammatory signaling can be complimentary to traditional molecular testing.

Prediction of line shape parameters and their temperature dependences for CO2-N2 using molecular dynamics simulations

We show in this paper that requantized classical molecular dynamics simulations (rCMDSs) are capable of predicting various refined spectral-shape parameters of absorption lines of CO₂ broadened by N₂ with high precision. Combining CMDSs and a requantization procedure, we computed the auto-correlation function of the CO₂ dipole moment responsible for the absorption transition. Its Fourier-Laplace transform directly yields the spectrum. Calculations were made for two temperatures, 200 and 296 K, at 1 atm and for a large range of Doppler widths, from the near-Doppler to the collision-dominant regimes. For each temperature and each line, the spectra calculated for various Doppler widths were simultaneously fit with the Hartmann-Tran (HT) profile. This refined profile, which takes into account the effects of the speed dependent collisional line broadening, the Dicke narrowing, and the collisional line mixing, was recommended as a reference model to be used in high-resolution spectroscopy (instead of the simplified Voigt model). The HT parameters retrieved from the rCMDS-calculated spectra were then directly compared with those deduced from high-precision measurements [J. S. Wilzewski et al., J. Quant. Spectrosc. Radiat. Transfer 206, 296-305 (2018)]. The results show a very good agreement, even for those parameters whose influence on the spectra is very small. Good agreement is also obtained between measured and predicted temperature dependences of these parameters. This demonstrates that rCMDS is an excellent tool, highly competitive with respect to high quality measurements for precise line-shape studies.

Synthesis, Processing, and Characterization of Helical Polypeptide Rod-Coil Mixed Brushes

Mixed polymer brushes of rod-type polypeptide and coil-type vinyl polymer brushes were synthesized via two sequential steps of vapor deposition surface-initiated ring-opening polymerization (SI-ROP) and surface-initiated atom transfer radical polymerization (SI-ATRP), respectively. The effect on polypeptide brushes by coil-type brushes of their surface morphology, film thickness, and orientation were investigated before and after solvent quenching processes using chloroform and acetone. Before solvent quenching, the as-grown coil-type brushes forced the polypeptide brushes to stand up from the surface, resulting in higher film thickness, but the polypeptide brushes remained randomly oriented. After solvent quenching, polypeptide brushes tended to aggregate into conical bundles with an orientation perpendicular to the substrate, but coil-type brushes restricted the free arrangement of the polypeptide brushes and lessen their upward movement. Changes in film thickness, rod orientation, morphology, and wettability were observed with increased molecular weight of the coil-type polymer in the mixed brushes.

Organized Screening Detects Breast Cancer for Vietnamese Women Over 40 Years Old 2017

Background and context: In the world, breast cancer is the second most common type of cancer, with >1 million cases being diagnosed each year. In Vietnam, according to the cancer registry, there are 12,533 new cases of cancer in 2012 and estimated at 22,612 in 2020. However, breast cancer can be cured if a woman is diagnosed at an early stage. Current screening programs in Vietnam are mainly organized in an active way by health workers, not by the “initiative” of the women. Aim: Community awareness raising on prevention and early detection of breast cancer; breast cancer screening for 10,000 Vietnamese women, especially for high-risk women, disadvantaged women, less chance for periodic health examination; mobilize the commitment of businesses to provide screening for women´s cancer in the regular health check-ups for female employees; make it become lifestyle of women to get screened every year. Strategy/Tactics: Invited women over 40 years old to free breast cancer screening at cancer clinics/hospital in the north, central and south of Vietnam. 100% of the women were clinically examined and free breast ultrasound. Suspected women were provided mammography; in addition, ∼20 companies/businesses were aware the program and invited to join the screening. Program/Policy process: We have registered counters in hospitals that offer screening. Women who care for relatives or visit sick people can register at the counter. In addition, we have a Web site and a hotline for the reception of screening candidates. We have volunteers who were texting to remind women who have been involved in screening from previous years to continue screening this year. To facilitate the screening of women without affecting their daily work as well as those who are far away, free screening was offered on Saturday and Sunday of 4 consecutive weeks. We also went to businesses where the majority of workers are women to organize screening. We have held “Doctor´s Talk” before each screening session. We have invited cancer specialists, celebrities and patients with breast cancer who have been cured of the disease to talk about the prevention of breast cancer. Throughout the talk, 150-200 women were registered to hear the counsel. Outcomes: 10,095 women came for breast screening, with 1126 mammographies, including 50 suspected cases and 11 cases of cancer. The rate of reexamination in 2017 is 9.5% (the rate of women who have screened in 2015 is 1.7%, 2016 is 6.7%, and 1.1% in both 2015 and 2016). What was learned: After 3 years, our project for screening detection of breast cancer was examination for 32,136 Vietnamese woman; mammography for 2851 woman; detected 130 suspected cases of cancer and 25 cases identified cancer. For cancer cases, we recommended and supported them at cancer hospital. In cases of suspicion, we have followed up and reminded them to regularly visit and immediately go to hospital if there are abnormal signs.

Local Consolidation Therapy (LCT) After First Line Tyrosine Kinase Inhibitor (TKI) for Patients With EGFR Mutant Metastatic Non-small-cell Lung Cancer (NSCLC)

INTRODUCTION

Although most NSCLC patients with sensitizing epidermal growth factor receptor (EGFR) mutations have an impressive initial response, the vast majority has residual disease and develops acquired resistance after 9 to 14 months of EGFR tyrosine kinase (TKI) therapy. We recently reported a phase II trial showing that, for patients with molecularly unselected oligometastatic NSCLC who did not progress after first-line systemic therapy, local consolidation therapy (LCT) with surgery or radiation improved progression-free survival (PFS), compared with maintenance therapy alone. Herein, we report a retrospective analysis of LCT after TKI in patients with metastatic EGFR mutant NSCLC.

PATIENTS AND METHODS

We identified patients with metastatic EGFR mutant NSCLC treated with TKI plus LCT or with TKI alone in the MD Anderson GEMINI (Genomic Marker-Guided Therapy Initiative) database and in our recently published LCT trial. PFS was compared between LCT plus TKI and TKI only treated patients using the log-rank test.

RESULTS

We identified 129 patients with EGFR mutant NSCLC who were treated with first-line TKI and 12 that were treated with TKI followed by LCT. Among the 12 patients treated with TKI plus LCT, 8 patients had oligometastatic disease (defined as ≤ 3 metastases), and 4 patients had > 3 metastases. LCT regimens were hypofractionated radiotherapy or stereotactic ablative body radiotherapy for 11 patients and surgery for 1 patient. TKI followed by LCT resulted in a significantly longer PFS (36 months) compared with TKI alone (PFS, 14 months; log-rank P = .0024).

CONCLUSIONS

Our data suggests that first-line TKI plus LCT is a promising therapeutic strategy for patients with EGFR mutant NSCLC that merits further investigation.

Cefotetan-Induced Hemolytic Anemia: Case Series and Review

PURPOSE

To raise awareness of cefotetan-induced hemolytic anemia, a known rare but serious side effect that occurred in 5 patients at our medical center.

SUMMARY

Five cases of cefotetan-induced hemolytic anemia, which presented over the period of a single year at our center, are described. In each case, hemolytic anemia was confirmed by testing for the presence of anti-cefotetan antibodies. Each case occurred approximately 1 to 2 weeks following exposure to the drug. All five patients survived. A brief review of drug-induced immune hemolytic anemia (DIIHA) is also discussed.

CONCLUSION

DIIHA may be difficult to distinguish from other causes of hemolytic anemia, but should be included in the differential in patients exposed to medications associated with DIIHA. Once suspected, antibody testing should be performed, and once diagnosed, further exposure should be avoided.

S, Fujimoto J, Tong P, Diao L, Li L, Bolisetty M, Kalhor N, Lawson P, Vasquez M, Tran H, Wistuba II, Glisson B, Zhang J, Swisher SG, Roth JA, Heymach JV, Robson P, Wang J, Byers LA. Abstract 990: Single-cell profiling of small cell lung cancer circulating tumor cell-derived xenograft models reveals intratumoral heterogeneity among mediators of chemoresistance

Small cell lung cancer (SCLC) accounts for 14% of lung cancer diagnoses in the United States and is characterized by rapid onset of chemoresistance and poor clinical outcomes. Once considered a homogeneous disease, recent analyses of SCLC have identified intratumoral heterogeneity (ITH) with respect to NOTCH signaling, ASCL1/NEUROD1 balance and MYC amplification - all of which are potential mechanisms underlying SCLC's aggressive and refractory biology. Unfortunately, patient-derived models of SCLC with which to better characterize the molecular profiles of refractory SCLC are scarce. To address this, we generated circulating tumor cell-derived xenograft (CDX) models from liquid biopsies of patients with treatment-naïve or relapsed SCLC. Each CDX model underwent pathological review to confirm tumors were consistent with SCLC based on histology and standard immunohistochemical markers (e.g., TTF1, chromogranin A, synaptophysin, NCAM). Sequencing of these models revealed mutations typical of SCLC (e.g. TP53, RB1), which were maintained in vivo over multiple passages. Importantly, each model's in vivo response to cisplatin matched the patient's platinum response at the time of CDX generation. At the proteomic level, platinum-resistant models exhibited mTOR activation, increased SOX2 and ATM, and reduced E-cadherin, suggesting a shift toward EMT and cancer stem cell expansion may contribute to resistance. To investigate ITH, we analyzed single-cell gene expression profiles by RNAseq using a droplet-based Chromium Single Cell system that analyzed a filtered subsample of 2000 cells per tumor. Consistent with SCLC, all CDX models contained large numbers of cells expressing neuroendocrine-specific genes (SYP, CHGA). However, Principle Component Analysis revealed that cells from chemosensitive CDX models had distinct expression profiles from resistant models. Using our published EMT gene signature, we found that resistant models had higher proportions of mesenchymal (vs. epithelial) cells. Several other distinctions between sensitive and resistant models were detected at the single-cell level but not in bulk RNA and protein analyses, suggesting that single-cell resolution can identify occult platinum-resistant subpopulations. For example, higher proportions of ASCL1- and DLL3-expressing cells were associated with platinum sensitivity, whereas a shift toward predominant NEUROD1-expression was observed with resistance. Cells expressing each of these three genes were identified across all tumors, suggesting platinum-sensitive and resistant subpopulations are ubiquitous but that even subtle shifts in the fractional distribution of these subsets can exert significant impact on response. These data support further use of single-cell analysis to explore the role of ITH as a driver of drug resistance in SCLC.

Citation Format: C. Allison Stewart, Carl M. Gay, Yuanxin Xi, Siva V., Junya Fujimoto, Pan Tong, Lixia Diao, Lerong Li, Mohan Bolisetty, Neda Kalhor, Patrice Lawson, Mayra Vasquez, Hai Tran, Ignacio I. Wistuba, Bonnie Glisson, Jianjun Zhang, Stephen G. Swisher, Jack A. Roth, John V. Heymach, Paul Robson, Jing Wang, Lauren A. Byers. Single-cell profiling of small cell lung cancer circulating tumor cell-derived xenograft models reveals intratumoral heterogeneity among mediators of chemoresistance [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 990.