Phenotypic Heterogeneity of Circulating Tumor Cells Informs Clinical Decisions between AR Signaling Inhibitors and Taxanes in Metastatic Prostate Cancer

The heterogeneity of an individual patient's tumor has been linked to treatment resistance, but quantitative biomarkers to rapidly and reproducibly evaluate heterogeneity in a clinical setting are currently lacking. Using established tools available in a College of American Pathologists-accredited and Clinical Laboratory Improvement Amendments-certified clinical laboratory, we quantified digital pathology features on 9,225 individual circulating tumor cells (CTC) from 179 unique metastatic castration-resistant prostate cancer (mCRPC) patients to define phenotypically distinct cell types. Heterogeneity was quantified on the basis of the diversity of cell types in individual patient samples using the Shannon index and associated with overall survival (OS) in the 145 specimens collected prior to initiation of the second or later lines of therapy. Low CTC phenotypic heterogeneity was associated with better OS in patients treated with androgen receptor signaling inhibitors (ARSI), whereas high heterogeneity was associated with better OS in patients treated with taxane chemotherapy. Overall, the results show that quantifying CTC phenotypic heterogeneity can help inform the choice between ARSI and taxanes in mCRPC patients. Cancer Res; 77(20); 5687-98. ©2017 AACR.

Cerebrospinal fluid circulating tumor cells (CSF CTC) for real-time patient monitoring and response to treatment

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Background: The validated CellSearch system (Janssen Diagnostics, LLC), utilizing an immunomagnetic CTC selection method based on EPCAM antibody conjugated ferroparticles, is an FDA-approved methodology for enumerating CTC from blood in pts with breast, prostate and colon cancers. The CellSearch system has been used to evaluate CSF CTC of pts with leptomeningeal metastasis (LM) and has demonstrated potential as a diagnostic marker and response to cancer treatment. We explored the use of CSF CTC enumeration in the follow-up of pts with LM from HER2+ cancers receiving intrathecal (IT) therapy, aimed at characterizing changes over time as a potential biomarker of treatment response. Methods: CSF from pts participating in an IRB-approved phase I/II dose escalation trial of IT trastuzumab for LM in HER2+ cancer (NCT01325207) was evaluated by CellSearch system. 3 ml CSF from a ventricular reservoir was collected for CSF CTC enumeration at pre-treatment Day 1 of each cycle and correlated with CSF cytology from the same sample, and with clinical and radiographic response. LM progression was defined as clinical, CSF cytologic or radiographic worsening. Results: 15 pts with HER2+ LM (14 breast, 1 colon) were enrolled; 13 were women. At baseline 7 pts had positive CSF cytology, the other patients had a diagnosis by MRI. Of the 15 pts, 10 had greater than 1 cycle of treatment to be evaluable; 5 pts progressed during cycle 1 (Table). Mean CSF CTC at baseline was 82 per 3ml (range 0-200); 2 pts had no detectable CSF CTCs. A numerical decrease in CSF CTC was observed in 5 pts after cycle 1 and remained low (mean =9.5, range 0-92) while disease was stable. 3 pts (pts.3, 4 and 7) demonstrated a rise in CSF CTCs roughly 1 month prior to disease progression. Conclusions: Changes in CSF CTCs enumeration in response to treatment may allow quantitative surveillance of treatment response. CSF CTCs may serve as a platform to assess treatment response or as an early biomarker of LM progression and should be further investigated. Clinical trial information: NCT01325207. [Table: see text]

Baseline CTC subtype to predict outcomes on mCRPC patients (pts) receiving enzalutamide (E) compared to abiraterone (A)

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Background: Prior response to A or E does not predict sensitivity to E following A or A following E. The detection of AR-V7 predicts insensitivity to either drug, but identifies only a portion of non-responders. We previously identified 15 CTC subtypes based on unique phenotypic features in mCRPC pts, each with unique biology and different degree of likelihood of predicting resistance to either drug. Here we explored the relationship between individual subtypes and sensitivity to A vs. E, but not both. Methods: 107 pre-treatment blood samples from mCRPC pts starting A (n = 47) or E (n = 60) as a 1st or 2nd line of Tx were analyzed for CTCs utilizing the Epic Sciences platform. Samples were assayed for CTC subtypes based upon 15 pre-defined phenotypic CTC classifiers (Type A-O). Treatment outcomes were assessed by serial PSA changes and landmarked percent time of therapy progression on radiographs, and overall survival following either A or E. Cell type prevalence was also analyzed in relation to clinical outcomes, and subsets of the CTC subtypes subject to single cell NGS to ascertain genomic drivers common to each subtype. Results: CTCs were identified in 94% (101/107) of pt samples. One, cell Type K, found in 25% (27/107) of pts, was associated with a statistically significant inferior outcomes on E for all measures. Whereas similar outcomes were seen between K+ & K- pts treated with A. The distinct features of Cell Type K include a large nucleus, high nuclear entropy and high Nuclear/cytoplasmic AR terminal ratio; and a unique genomic profile enriched for cell cycle and DNA repair alterations relative to other CTC subtypes. Conclusions: The presence of specific CTC subtypes in pre-Rx phlebotomy samples associated with outcomes on A or E. A CTC subtype (Cell Type K) helped to identify pts with poor outcomes on E but not A vs. those without the cell type. Further biologic interrogation of K cells and ongoing clincial validation of the CTC subtype is planned. [Table: see text]

Changes in CTC burden and prevalence of specific CTC subtypes in mCRPC patients (pts) receiving alpharadin (Ra-223) as single agent or in combination with other therapuetics (Tx)

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Background: Ra-223 prolongs life in mCRPC pts with symptomatic osseous metastasis with inconsistent effects on PSA. Survival times are prolonged further when combined with Abi/Enza. Data from preclinical studies suggest that Ra-223 may sensitize tumors to DDR agents and/or biologic therapies. But predictive biomarkers of benefit to each or both combinationso are lacking. We studied CTC counts and the prevelance of specific CTC subtypes in patients before and following Ra-223 therapy, both as a single agent and in combination, to identify biomarkers of sensitivity and treatement efficacy, and effects of Ra-223 on tumor biology. Methods: Pre and ~4 week post RA-223 therapy blood samples were collected from 35 pts (2 samples each) given as a single agent (n = 20 pts) or in combination with other therapies (n = 15 pts, 9 w/ Enza, 5 w/ Abi, 1 w/ Taxane). Samples were processed and CTCs analyzed using the Epic Sciences platform. Total CTC count and the prevalence of specific CTC phenotypes present pre and post Rx were identified utilizing high content digital pathology and associated with therapy type and post-treatment change. Results: CTC declines were observed in 55% (11/20) and 60% (9/15) of pts treated with single agent and combination respectively. In Ra-223 alone pts, a novel CTC subtype (high N/C ratio, high nuclear area) was identified at baseline 11/20 samples (med = 33% of CTCs). Which was no longer detected in 10 (90%) of the pts treated. This contrasts with a second novel CTC subtype present at baseline in 4 pts (med CTC = 9%) that increased to 9 cases (med CTC = 18%) at follow-up. Conclusions: A subset of pts demonstrate post-therapy CTC declines following Ra-223 alone or in combination. A novel CTC subtype resolved by RA-223 in conjunction with total CTC kinetics may indicate pt benefit from Ra-223. A novel emergent CTC subtype has also been identified in pts already receiving Ra-223. Single CTC sequencing and protein analysys of these CTC subtypes are ongoing, and may help describe tumor evolution and sensitization to novel therapuetics.

Two cases of spontaneous remission of non-parasitic chyluria

OBJECTIVES

Chyluria is a medical condition with presence of chyle in urine. The disease is most prevalent in South East Asian countries mostly caused by parasitic (Wuchereria bancrofti) infections. Our objective was to investigate the spontaneous remission of non-parasitic chyluria.

DESIGN AND METHODS

The spontaneous remission of non-parasitic chyluria cases were worked up with diagnostic investigations, clinical assessment and studied in detail with respect to their natural evolution.

RESULTS

We present two patients who were evaluated in the nephrology clinic with symptoms of milky urine and painless hematuria. Midnight blood smear was negative for filarial parasites. Urine culture was without mycobacteria. Urine cytology and IgG western blot for cysticercus were negative. Imaging for a lymphatic leak by lymphoscintigraphy was unrevealing. Chyluria resolved spontaneously in both patients.

CONCLUSIONS

In our cases, radiologic visualization via lymphoscintigraphy was unrevealing. The patients were managed conservatively and fortunately underwent spontaneous remission marked by the disappearance of chyluria within several months of her initial diagnosis. In our opinion this spontaneous remission could be due to unrevealed lymphatico-renal fistula collapse or sclerosis of lymphatics caused by contrast media.

Single cell phenogenomic subtyping of circulating tumor cells (CTCs) identify intercellular tumor heterogeneity (het) and multiple resistance mechansisms in patients (pts) with metastatic castration-resistant prostate cancer (mCRPC)

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Background: Genomic profiling of metastatic tumors can identify mCRPC pts w/ “actionable” targets. However, responses from this approach are infrequent and not durable, broadly attributed to intra-tumor and intrer-cellular het. We sought to understand relationships between single CTC phenotypic and genomic patterns present when starting ARSi or taxane therapy (Tx) to develop more effective biomarker-directed treatment approaches. Methods: 9225 CTCs from 319 blood samples from 179 mCRPC pts were detected and digital phenotypically profiled using the Epic Sciences platform. Unsupervised clustering revealed 15 phenotypic CTC subtypes based on digital pathology features (Type ‘A’-‘O’). Phenotypic diversity was determined by a Shannon index of these subtypes in pt samples. Next, 856 CTCs representing each subtype were individually whole genome sequenced for copy number variation and genomic instability, to define phenogenomic single cell profile and taxonomy. Tx outcomes were associated with CTC profiles. Results: Pre-therapy identification of certain CTC phenotypic subtypes was associated with poor overall survival (OS) following ARSi and/or taxanes. 5/15 subtypes existed primarily in pts w/ high CTC het (84-94%, Bonferroni adjusted p < 0.05, permutation test), and linked to amp of AR and cMYC, and loss of TP53 and PTEN. Clusters of genomic events were linked to phenotypic features (i.e. small cell CTC w/AuroraK & nMYC amp) and provide single cell phenogenomic associations with pathways such as AR/PTEN feedback and DNA repair machinery. Conclusions: Presence ofspecific CTC subtypes was associated w/ poor survival on ARSi and/or taxanes and may inform Tx selection. Identifying CTC subtypes present in high het samples can provide insight into individual pt disease evolution and potential approaches to maximize benefit. Longitudinal monitoring of CTC phenogenomics is being studied in novel Tx trials.[Table: see text]

Association of AR-V7 on Circulating Tumor Cells as a Treatment-Specific Biomarker With Outcomes and Survival in Castration-Resistant Prostate Cancer

Importance

A critical decision in the management of metastatic castration-resistant prostate cancer (mCRPC) is when to administer an androgen receptor signaling (ARS) inhibitor or a taxane.

Objective

To determine if pretherapy nuclear androgen-receptor splice variant 7 (AR-V7) protein expression and localization on circulating tumor cells (CTCs) is a treatment-specific marker for response and outcomes between ARS inhibitors and taxanes.

Design, Setting, and Participants

For this cross-sectional cohort study at Memorial Sloan Kettering Cancer Center, 265 men with progressive mCRPC undergoing a change in treatment were considered; 86 were excluded because they were not initiating ARS or taxane therapy; and 18 were excluded for processing time constraints, leaving 161 patients for analysis. Between December 2012 and March 2015, blood was collected and processed from patients with progressive mCRPC immediately prior to new line of systemic therapy. Patients were followed up to 3 years.

Main Outcomes and Measures

Prostate-specific antigen (PSA) response, time receiving therapy, radiographic progression-free survival (rPFS), and overall survival (OS).

Results

Overall, of 193 prospectively collected blood samples from 161 men with mCRPC, 191 were evaluable (128 pre-ARS inhibitor and 63 pretaxane). AR-V7-positive CTCs were found in 34 samples (18%), including 3% of first-line, 18% of second-line, and 31% of third- or greater line samples. Patients whose samples had AR-V7-positive CTCs before ARS inhibition had resistant posttherapy PSA changes (PTPC), shorter rPFS, shorter time on therapy, and shorter OS than those without AR-V7-positive CTCs. Overall, resistant PTPC were seen in 65 of 112 samples (58%) without detectable AR-V7-positive CTCs prior to ARS inhibition. There were statistically significant differences in OS but not in PTPC, time on therapy, or rPFS for patients with or without pretherapy AR-V7-positive CTCs treated with a taxane. A multivariable model adjusting for baseline factors associated with survival showed superior OS with taxanes relative to ARS inhibitors when AR-V7-positive CTCs were detected pretherapy (hazard ratio, 0.24; 95% CI, 0.10-0.57; P = .035).

Conclusions and Relevance

The results validate CTC nuclear expression of AR-V7 protein in men with mCRPC as a treatment-specific biomarker that is associated with superior survival on taxane therapy over ARS-directed therapy in a clinical practice setting. Continued examination of this biomarker in prospective studies will further aid clinical utility.

Nuclear-specific AR-V7 Protein Localization is Necessary to Guide Treatment Selection in Metastatic Castration-resistant Prostate Cancer

BACKGROUND

Circulating tumor cells (CTCs) expressing AR-V7 protein localized to the nucleus (nuclear-specific) identify metastatic castration-resistant prostate cancer (mCRPC) patients with improved overall survival (OS) on taxane therapy relative to the androgen receptor signaling inhibitors (ARSi) abiraterone acetate, enzalutamide, and apalutamide.

OBJECTIVE

To evaluate if expanding the positivity criteria to include both nuclear and cytoplasmic AR-V7 localization ("nuclear-agnostic") identifies more patients who would benefit from a taxane over an ARSi.

DESIGN, SETTING, AND PARTICIPANTS

The study used a cross-sectional cohort. Between December 2012 and March 2015, 193 pretherapy blood samples, 191 of which were evaluable, were collected and processed from 161 unique mCRPC patients before starting a new line of systemic therapy for disease progression at the Memorial Sloan Kettering Cancer Center. The association between two AR-V7 scoring criteria, post-therapy prostate-specific antigen (PSA) change (PTPC) and OS following ARSi or taxane treatment, was explored. One criterion required nuclear-specific AR-V7 localization, and the other required an AR-V7 signal but was agnostic to protein localization in CTCs.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSES

Correlation of AR-V7 status to PTPC and OS was investigated. Relationships with survival were analyzed using multivariable Cox regression and log-rank analyses.

RESULTS AND LIMITATIONS

A total of 34 (18%) samples were AR-V7-positive using nuclear-specific criteria, and 56 (29%) were AR-V7-positive using nuclear-agnostic criteria. Following ARSi treatment, none of the 16 nuclear-specific AR-V7-positive samples and six of the 32 (19%) nuclear-agnostic AR-V7-positive samples had ≥50% PTPC at 12 weeks. The strongest baseline factor influencing OS was the interaction between the presence of nuclear-specific AR-V7-positive CTCs and treatment with a taxane (hazard ratio 0.24, 95% confidence interval 0.078-0.79; p=0.019). This interaction was not significant when nuclear-agnostic criteria were used.

CONCLUSIONS

To reliably inform treatment selection using an AR-V7 protein biomarker in CTCs, nuclear-specific localization is required.

PATIENT SUMMARY

We analyzed outcomes for patients with metastatic castration-resistant prostate cancer on androgen receptor signaling inhibitors and standard chemotherapy. Patients with circulating tumor cells that had AR-V7 protein in the cellular nuclei were very likely to survive longer on taxane-based chemotherapy, and tests unable to distinguish where the protein is located in the cell are not as predictive of benefit.

First-in-Human Imaging with 89Zr-Df-IAB2M Anti-PSMA Minibody in Patients with Metastatic Prostate Cancer: Pharmacokinetics, Biodistribution, Dosimetry, and Lesion Uptake

We conducted a phase I dose-escalation study with ⁸⁹Zr-desferrioxamine-IAB2M (⁸⁹Zr-IAB2M), an anti-prostate-specific membrane antigen minibody, in patients with metastatic prostate cancer.

METHODS

Patients received 185 MBq (5 mCi) of ⁸⁹Zr-IAB2M and Df-IAB2M at total mass doses of 10 (n = 6), 20 (n = 6), and 50 mg (n = 6). Whole-body and serum clearance, normal-organ and lesion uptake, and radiation absorbed dose were estimated, and the effect of mass escalation was analyzed.

RESULTS

Eighteen patients were injected and scanned without side effects. Whole-body clearance was monoexponential, with a median biologic half-life of 215 h, whereas serum clearance showed biexponential kinetics, with a median biologic half-life of 3.7 (12.3%/L) and 33.8 h (17.9%/L). The radiation absorbed dose estimates were 1.67, 1.36, and 0.32 mGy/MBq to liver, kidney, and marrow, respectively, with an effective dose of 0.41 mSv/MBq (1.5 rem/mCi). Both skeletal and nodal lesions were detected with ⁸⁹Zr-IAB2M, most visualized by 48-h imaging.

CONCLUSION

⁸⁹Zr-IAB2M is safe and demonstrates favorable biodistribution and kinetics for targeting metastatic prostate cancer. Imaging with 10 mg of minibody mass provides optimal biodistribution, and imaging at 48 h after injection provides good lesion visualization. Assessment of lesion targeting is being studied in detail in an expansion cohort.

Abstract 4954: Nuclear localized AR-V7 protein as a predictive biomarker for treatment selection in metastatic castration resistant prostate cancer (mCRPC)

Background: A critical decision in the management of patients (pts) with mCRPC is when to administer an androgen receptor signaling (ARS) directed or a taxane therapy. The detection of AR-V7 mRNA in CTCs has been shown to predict for resistance to ARS,but not to taxane chemotherapy. We evaluated the relationship between AR-V7 protein expression and localization on CTCs to treatment outcomes in a separate, larger cohort as a predictive biomarker for clinical decision making.

Methods: 193 prospectively collected blood samples from 161 unique pts with progressive mCRPC about to start an ARS or taxane therapy were evaluated with an Epic Sciences CTC immunoflorescent assay that assesses CTC AR-V7 protein expression and localization in individual

cells. Associations between the presence AR-V7(+) CTCs pre-therapy and anti-tumor effects post-therapy included prostate-specific antigen (PSA) changes, radiographic progression free survival (rPFS), time on therapy, and overall survival (OS).

Results: 130 pre-ARS inhibitor and 63 pre-taxane samples were assessed of which 191 (99%) were evaluable. AR-V7(+) CTCs were found in 34 (18%) samples including 3% of the 1st, 18% of the 2nd and 31% of the 3rd+ line baseline pre-therapy samples. Patients with AR-V7 positive CTCs in a pre-ARS sample showed no PSA response and had shorter rPFS, time on therapy, and OS than those without AR-V7(+) CTCs. PSA resistance to ARS was also seen in 65 of 112 (58%) of the AR-V7(-) samples. There was no association between PSA response, rPFS, and time on therapy between AR-V7(+) and AR-V7(-) pts treated with taxane therapy. In a multivariate model adjusting for age, type of therapy, line of therapy, and pre-therapy LDH, Hgb, and presence of visceral metastasis, AR-V7(+) pts had a superior OS on taxane therapy relative to ARS (HR: 0.242, CI: 0.103 to 0.569, p = 0.0350). Conclusions: The results validate the expression of the AR-V7 protein in the nucleus of CTCs in men with mCRPC as a treatment specific biomarker that predicts resistance to ARS inhibitor therapy and separately, clinical benefit with taxane therapy over ARS-directed therapy in a clinical practice setting. Continued examination of this biomarker in prospective studies will further determine its clinical utility.

Citation Format: Howard I. Scher, David Lu, Nicole A. Schreiber, Jessica Louw, Ryon P. Graf, Ann Johnson, Adam Jendrisak, Glenn Heller, Richard Bambury, Herbert A. Vargas Alverez, Brigit McLaughlin, Justin Wahl, Stephanie Greene, Martin Fleisher, Ryan Dittamore. Nuclear localized AR-V7 protein as a predictive biomarker for treatment selection in metastatic castration resistant prostate cancer (mCRPC). [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 4954.

Decline in Circulating Tumor Cell Count and Treatment Outcome in Advanced Prostate Cancer

Background

Treatment response biomarkers are urgently needed for castration-resistant prostate cancer (CRPC). Baseline and post-treatment circulating tumor cell (CTC) counts of ≥5 cells/7.5 ml are associated with poor CRPC outcome.

Objective

To determine the value of a ≥30% CTC decline as a treatment response indicator.

Design, setting, and participants

We identified patients with a baseline CTC count ≥5 cells/7.5 ml and evaluable post-treatment CTC counts in two prospective trials.

Intervention

Patients were treated in the COU-AA-301 (abiraterone after chemotherapy) and IMMC-38 (chemotherapy) trials.

Outcome measures and statistical analysis

The association between a ≥30% CTC decline after treatment and survival was evaluated using univariable and multivariable Cox regression models at three landmark time points (4, 8, and 12 wk). Model performance was evaluated by calculating the area under the receiver operating characteristic curve (AUC) and c-indices.

Results

Overall 486 patients (122 in IMMC-38 and 364 in COU-AA-301) had a CTC count ≥5 cells/7.5 ml at baseline, with 440, 380, and 351 patients evaluable at 4, 8, and 12 wk, respectively. A 30% CTC decline was associated with increased survival at 4 wk (hazard ratio [HR] 0.45, 95% confidence interval [CI] 0.36–0.56; p < 0.001), 8 wk (HR 0.41, 95% CI 0.33–0.53; p < 0.001), and 12 wk (HR 0.39, 95% CI 0.3–0.5; p < 0.001) in univariable and multivariable analyses. Stable CTC count (<30% fall or <30% increase) was not associated with a survival benefit when compared with increased CTC count. The association between a 30% CTC decline after treatment and survival was independent of baseline CTC count. CTC declines significantly improved the AUC at all time-points. Finally, in the COU-AA-301 trial, patients with CTC ≥5 cells/7.5 ml and a 30% CTC decline had similar overall survival in both arms.

Conclusions

A 30% CTC decline after treatment from an initial count ≥5 cells/7.5 ml is independently associated with CRPC overall survival following abiraterone and chemotherapy, improving the performance of a multivariable model as early as 4 wk after treatment. This potential surrogate must now be prospectively evaluated.

Patient summary

Circulating tumor cells (CTCs) are cancer cells that can be detected in the blood of prostate cancer patients. We analyzed changes in CTCs after treatment with abiraterone and chemotherapy in two large clinical trials, and found that patients who have a decline in CTC count have a better survival outcome.

Vismodegib or cixutumumab in combination with standard chemotherapy for patients with extensive-stage small cell lung cancer: A trial of the ECOG-ACRIN Cancer Research Group (E1508)

BACKGROUND

Preclinical targeting of the hedgehog pathway by vismodegib and of insulin-like growth factor 1 receptor by cixutumumab enhances the efficacy of chemotherapy and also demonstrates activity against the tumor cell fraction responsible for disease recurrence in small cell lung cancer.

METHODS

Patients with newly diagnosed extensive-stage small cell lung cancer (SCLC-ED) were randomized to receive four 21-day cycles of cisplatin and etoposide alone (cisplatin at 75 mg/m(2) on day 1 and etoposide at 100 mg/m(2) on days 1-3; arm A) or in combination with either vismodegib (150 mg/d by mouth; arm B) or cixutumumab (6 mg/kg/wk intravenously on day 1; arm C). The primary endpoint was progression-free survival (PFS). Circulating tumor cells (CTCs) were isolated/enumerated with the Veridex CellSearch platform at the baseline.

RESULTS

One hundred fifty-two eligible patients were treated. Patient demographics and disease characteristics were well balanced between the 3 arms except for the higher rate with a performance status of 0 in arm B (P = .03). The median PFS times in arms A, B, and C were 4.4, 4.4, and 4.6 months, respectively; the median overall survival (OS) times were 8.8, 9.8, and 10.1 months, respectively; and the response rates were 48%, 56%, and 50%, respectively. None of the comparisons of these outcomes were statistically significant. The median OS was 10.5 months for those with low CTC counts (≤100/7.5 mL) at baseline and 7.2 months for those with high CTC counts (hazard ratio, 1.74; P = .006).

CONCLUSIONS

There was no significant improvement in PFS or OS with the addition of either vismodegib or cixutumumab to chemotherapy in patients with SCLC-ED. A low baseline CTC count was associated with a favorable prognosis. Cancer 2016;122:2371-2378. © 2016 American Cancer Society.

Evaluating Cancer of the Central Nervous System Through Next-Generation Sequencing of Cerebrospinal Fluid

PURPOSE

Cancer spread to the central nervous system (CNS) often is diagnosed late and is unresponsive to therapy. Mechanisms of tumor dissemination and evolution within the CNS are largely unknown because of limited access to tumor tissue.

MATERIALS AND METHODS

We sequenced 341 cancer-associated genes in cell-free DNA from cerebrospinal fluid (CSF) obtained through routine lumbar puncture in 53 patients with suspected or known CNS involvement by cancer.

RESULTS

We detected high-confidence somatic alterations in 63% (20 of 32) of patients with CNS metastases of solid tumors, 50% (six of 12) of patients with primary brain tumors, and 0% (zero of nine) of patients without CNS involvement by cancer. Several patients with tumor progression in the CNS during therapy with inhibitors of oncogenic kinases harbored mutations in the kinase target or kinase bypass pathways. In patients with glioma, the most common malignant primary brain tumor in adults, examination of cell-free DNA uncovered patterns of tumor evolution, including temozolomide-associated mutations.

CONCLUSION

The study shows that CSF harbors clinically relevant genomic alterations in patients with CNS cancers and should be considered for liquid biopsies to monitor tumor evolution in the CNS.

A phase I trial of the Hedgehog inhibitor, sonidegib (LDE225), in combination with etoposide and cisplatin for the initial treatment of extensive stage small cell lung cancer

OBJECTIVES

The Hedgehog pathway has been implicated in small cell lung cancer (SCLC) tumor initiation and progression. Pharmacologic blockade of the key Hedgehog regulator, Smoothened, may inhibit these processes. We performed a phase I study to determine the maximum tolerated dose (MTD) of sonidegib (LDE225), a selective, oral Smoothened antagonist, in combination with etoposide/cisplatin in newly diagnosed patients with extensive stage SCLC.

MATERIALS AND METHODS

Patients received 4-6 21-day cycles of etoposide/cisplatin with daily sonidegib. Patients with response or stable disease were continued on sonidegib until disease progression or unacceptable toxicity. Two dose levels of sonidegib were planned: 400mg and 800mg daily, with 200mg daily de-escalation if necessary. Next generation sequencing was performed on available specimens. Circulating tumor cells (CTCs) were quantified at baseline and with disease evaluation.

RESULTS

Fifteen patients were enrolled. 800mg was established as the recommended phase II dose of sonidegib in combination with etoposide/cisplatin. Grade 3 or greater toxicities included: anemia (n=5), neutropenia (n=8), CPK elevation (n=2), fatigue (n=2), and nausea (n=2). Toxicity led to removal of one patient from study. Partial responses were confirmed in 79% (11/14; 95% CI: 49-95%). One patient with SOX2 amplification remains progression-free on maintenance sonidegib after 27 months. CTC count, at baseline, was associated with the presence of liver metastases and after 1 cycle of therapy, with overall survival.

CONCLUSIONS

Sonidegib 800mg daily was the MTD when administered with EP. Further genomic characterization of exceptional responders may reveal clinically relevant predictive biomarkers that could tailor use in patients most likely to benefit.