Rapid interrogation of cancer cell of origin through CRISPR editing.

The increasing complexity of different cell types revealed by single-cell analysis of tissues presents challenges in efficiently elucidating their functions. Here we show, using prostate as a model tissue, that primary organoids and freshly isolated epithelial cells can be CRISPR edited ex vivo using Cas9-sgRNA (guide RNA) ribotnucleoprotein complex technology, then orthotopically transferred in vivo into immunocompetent or immunodeficient mice to generate cancer models with phenotypes resembling those seen in traditional genetically engineered mouse models. Large intrachromosomal (∼2 Mb) or multigenic deletions can be engineered efficiently without the need for selection, including in isolated subpopulations to address cell-of-origin questions.

Four Cycles of Etoposide plus Cisplatin for Patients with Good-Risk Advanced Germ Cell Tumors.

BACKGROUND: The National Comprehensive Cancer Network recommends either three cycles of bleomycin, etoposide, and cisplatin or four cycles of etoposide and cisplatin (EPx4) as initial chemotherapy for the treatment of good-risk germ cell tumors (GCTs). To assess the response, toxicity, and survival outcomes of EPx4, we analyzed our experience. MATERIAL AND METHODS: Response and survival outcomes, selected toxicities, and adherence to chemotherapy dose and schedule were assessed in patients with good-risk GCT who received EPx4 at Memorial Sloan Kettering Cancer Center between 1982 and 2016. The results were compared with our past results and published data. RESULTS: Between 1982 and 2016, 944 patients with GCT were treated with EPx4, 289 who were previously reported plus 655 treated between January 2000 and August 2016. A favorable response was achieved in 928 of 944 patients (98.3%). Five-year progression-free, disease-specific, and overall survival rates were 93.9%, 98.6%, and 97.9%, respectively. Median follow-up was 7.3 years (range, 2.8 months to 35.5 years). Viable, nonteratomatous malignant GCT was present in 3.5% of 432 postchemotherapy retroperitoneal lymph node dissection specimens from patients with nonseminomatous GCT. Febrile neutropenia and thromboembolic events occurred in 16.0% and 8.9%, respectively, with one treatment-related death. In the more recent 655-patient cohort, full-dose EPx4 was administered to 631 (96.3%), with deviations from planned treatment driven mainly by vascular (n = 13), hematologic (n = 11), renal (n = 7), or infectious (n = 5) events. CONCLUSION: EPx4 is highly effective and well tolerated in patients with good-risk GCTs and remains a standard of care. IMPLICATIONS FOR PRACTICE: Four cycles of etoposide and cisplatin (EPx4) is a standard-of-care regimen for all patients with good-risk germ cell tumors with a favorable response rate and disease-specific survival of 98%. Full-dose administration of etoposide and cisplatin and complete resection of residual disease lead to optimal outcomes. EPx4 should be the recommended regimen in active smokers, patients with reduced or borderline kidney function, and patients aged 50 years or older, which are patient groups at increased risk for bleomycin pulmonary toxicity. Because of a risk of acquired severe pulmonary illness, EPx4 may also be favored for patients who vape or use e-cigarettes and during ongoing transmission of severe acute respiratory syndrome coronavirus 2.

A phase II study of the dual mTOR inhibitor MLN0128 in patients with metastatic castration resistant prostate cancer.

Background MLN0128 is a first-in-class, dual mTOR inhibitor with potential to outperform standard rapalogs through inhibition of TORC1 and TORC2. This phase II study was designed to assess antitumor activity of MLN0128 in metastatic castration-resistant prostate cancer (mCRPC). Methods Eligible patients had mCRPC previously treated with abiraterone acetate and/or enzalutamide. Five patients started MLN0128 at 5 mg once daily, subsequently dose reduced to 4 mg because of toxicity. Four subsequent patients started MLN0128 at 4 mg daily. Primary endpoint was progression-free survival at 6 months. Results Nine patients were enrolled and median time on treatment was 11 weeks (range: 3-30). Best response was stable disease. All patients had a rise in PSA on treatment, with a median 159% increase from baseline (range: 12-620%). Median baseline circulating tumor cell count was 1 cell/mL (range: 0-40); none had a decrease in cell count posttreatment. Grade ≤ 2 adverse events included fatigue, anorexia, and rash. The most common serious adverse events were grade 3 dyspnea and maculopapular rash. Eight patients discontinued treatment early because of radiographic progression (n = 1), grade 3 toxicity (n = 5), or investigator discretion (n = 2). Four patients had immediate PSA decline following drug discontinuation, suggesting MLN0128 could cause compensatory increase of androgen receptor (AR) activity. Correlative studies of pretreatment and posttreatment biopsy specimens revealed limited inhibition of AKT phosphorylation, 4EBP1 phosphorylation, and eIF4E activity. Conclusions Clinical efficacy of MLN0128 in mCRPC was limited likely due to dose reductions secondary to toxicity, PSA kinetics suggesting AR activation resulting from mTOR inhibition, and poor inhibition of mTOR signaling targets.

Clinical Outcome of Patients with Fibrosis/Necrosis at Post-Chemotherapy Retroperitoneal Lymph Node Dissection for Advanced Germ Cell Tumors.

PURPOSE: Fibrosis accounts for approximately 50% of histological findings at post-chemotherapy retroperitoneal lymph node dissection, and is associated with reported relapse rates of 10% to 15%. We characterized patients with fibrosis at post-chemotherapy retroperitoneal lymph node dissection and identified predictors of adverse outcomes in this group. MATERIALS AND METHODS: We reviewed the medical records of men who underwent post-chemotherapy retroperitoneal lymph node dissection between 1989 and 2013 with histological findings of necrosis/fibrosis. With few exceptions post-chemotherapy retroperitoneal lymph node dissection after 1999 was performed with a bilateral template. Clinical, pathological and treatment related data were reported. Cox regression models were built to identify predictors of disease recurrence. RESULTS: The study cohort included 598 men with a median age of 32 years (IQR 25-38). Most cases (397 of 547, 73%) were classified as IGCCCG good risk, with no significant differences in risk classification before and after 1999 (p=0.55). Median followup was 7.3 years (IQR 3.2-12.3). The 5-year recurrence-free and overall survival rates were 94% and 96%, respectively. Overall 36 patients had disease recurrence, most of which was distant or outside the retroperitoneal lymph node dissection template. Procedures performed after 1999 and the presence of embryonal cell carcinoma on primary histology were associated with improved recurrence-free survival on multivariate analysis (p <0.01). CONCLUSIONS: Disease recurrence in patients with fibrosis at post-chemotherapy retroperitoneal lymph node dissection is an uncommon yet significant event, which is less likely to occur in patients treated after 1999 and in those with embryonal carcinoma on primary histology.

Copy number alteration burden predicts prostate cancer relapse.

Primary prostate cancer is the most common malignancy in men but has highly variable outcomes, highlighting the need for biomarkers to determine which patients can be managed conservatively. Few large prostate oncogenome resources currently exist that combine the molecular and clinical outcome data necessary to discover prognostic biomarkers. Previously, we found an association between relapse and the pattern of DNA copy number alteration (CNA) in 168 primary tumors, raising the possibility of CNA as a prognostic biomarker. Here we examine this question by profiling an additional 104 primary prostate cancers and updating the initial 168 patient cohort with long-term clinical outcome. We find that CNA burden across the genome, defined as the percentage of the tumor genome affected by CNA, was associated with biochemical recurrence and metastasis after surgery in these two cohorts, independent of the prostate-specific antigen biomarker or Gleason grade, a major existing histopathological prognostic variable in prostate cancer. Moreover, CNA burden was associated with biochemical recurrence in intermediate-risk Gleason 7 prostate cancers, independent of prostate-specific antigen or nomogram score. We further demonstrate that CNA burden can be measured in diagnostic needle biopsies using low-input whole-genome sequencing, setting the stage for studies of prognostic impact in conservatively treated cohorts.

Inhibition of circulating dipeptidyl peptidase 4 activity in patients with metastatic prostate cancer.

Cancer is responsible for many deaths and is a major source of healthcare expenditures. The identification of new, non-invasive biomarkers might allow improvement of the direct diagnostic or prognostic ability of already available tools. Here, we took the innovative approach of interrogating the activity of exopeptidases in the serum of cancer patients with the aim of establishing a distinction based on enzymatic function, instead of simple protein levels, as a means to biomarker discovery. We first analyzed two well-characterized mouse models of prostate cancer, each with a distinct genetic lesion, and established that broad exopeptidase and targeted aminopeptidase activity tests reveal proteolytic changes associated with tumor development. We also describe new peptide-based freeze-frame reagents uniquely suited to probe the altered balance of selected aminopeptidases, as opposed to the full array of exopeptidases, and/or their modulators in patient serum or plasma. One particular proteolytic activity was impaired in animals with aggressive disease relative to cancer-free littermates. We identified the protease in question as dipeptidyl peptidase 4 (DPP4) by analyzing selected knockout mice and evaluating the effect of specific inhibitors. DPP4 activity was also reduced in the sera of patients with metastatic prostate cancer relative to patients with localized disease or healthy controls. However, no significant differences in DPP4 serum levels were observed, which established the loss of activity as the result of impaired enzymatic function. Biochemical analysis indicated that reduced activity was the result not of post-translational modifications or allosteric changes, but instead of a low-molecular-weight inhibitor. After we adjusted for age and total prostate-specific antigen, reduced DPP4 activity remained a significant predictor of cancer status. The results of this proof-of-principle study suggest that DPP4 activity might be a potential blood-based indicator of the presence of metastatic cancer of prostatic origin, either by itself or, more likely, as a means to improve the sensitivity and specificity of existing markers.

Rates of teratoma and viable cancer at post-chemotherapy retroperitoneal lymph node dissection after induction chemotherapy for good risk nonseminomatous germ cell tumors.

PURPOSE: Patients with good risk nonseminomatous germ cell tumors received induction chemotherapy with 4 cycles of etoposide and cisplatin (EPx4) or 3 cycles of bleomycin, etoposide and cisplatin (BEPx3). We report the histological results at post-chemotherapy retroperitoneal lymph node dissection after induction chemotherapy in patients treated with etoposide and cisplatin or bleomycin, etoposide and cisplatin for good risk nonseminomatous germ cell tumors. MATERIALS AND METHODS: Post-chemotherapy retroperitoneal lymph node dissection was performed in 579 patients after induction chemotherapy. Of these patients 505 were treated with EPx4 and 74 were treated with BEPx3 or BEPx4. Clinical and pathological features are reported. RESULTS: No difference in the frequency of viable residual cancer was observed with bleomycin, etoposide and cisplatin vs etoposide and cisplatin (5% vs 6%, respectively, p=not significant). Teratoma was more prevalent in the bleomycin, etoposide and cisplatin group vs etoposide and cisplatin group (57% vs 34%, respectively, p <0.001). On multivariate analysis patients who received induction bleomycin, etoposide and cisplatin had a twofold greater risk of harboring teratoma at post-chemotherapy retroperitoneal lymph node dissection (OR 2.0; 95% CI 1.0, 4.0; p=0.04). When excluding patients from analysis who received BEPx4, those who received BEPx3 still had a 3.7-fold increased risk of teratoma in the retroperitoneum (OR 3.7; 95% CI 1.5, 8.9; p=0.004). Relapse-free and disease specific survival was not different between the 2 regimens. CONCLUSIONS: Viable cancer was equally uncommon after treatment with both regimens. Overall, relapse-free and disease specific survival did not differ between the groups. The discrepancy between regimens in the frequency of teratoma is not explained but may be due to an unrecognized selection bias rather than an effect of the regimen.

ETS rearrangements and prostate cancer initiation.

The first recurrent translocation event in prostate cancer has been recently described; it results in the translocation of an ETS (E26 transformation specific) transcription factor (ERG or ETV1) to the TMPRSS2 promoter region, which contains androgen responsive elements. The TMPRSS2:ERG genetic rearrangement has been reported to occur in approximately 40% of primary prostate tumours (ETV1 genetic rearrangements occur at a much lower frequency), and it results in the aberrant androgen-regulated expression of ERG. Tomlins et al. concluded that ETS genetic rearrangements are sufficient to initiate prostate neoplasia. However, here we show that ETS genetic rearrangements may in fact represent progression events rather than initiation events in prostate tumorigenesis. To this end, we demonstrate that the prostate-specific overexpression of ERG does not initiate prostate tumorigenesis.

Cabozantinib resolves bone scans in tumor-naïve mice harboring skeletal injuries.

The receptor tyrosine kinase inhibitor cabozantinib (XL184, BMS-907351 Cometriq) has displayed impressive clinical activity against several indications, culminating in its recent approval for medullary thyroid cancer. Among malignancies with tropism for the bone (prostate, breast), one striking feature of early clinical reports about this drug has been the rapid and complete resolution of bone scans, a phenomenon almost never observed even among therapies already shown to confer survival benefit. In castration-resistant prostate cancer, not all conventional response indicators change as dramatically posttreatment, raising the possibility that cabozantinib may impair the ability of bone-seeking radionuclides to integrate within the remodeling bone. To test this hypothesis, we surgically induced bone remodeling via physical insult in non-tumor-bearing mice and performed 18F-sodium fluoride (18F-NaF) positron emission tomographic (PET) and technetium 99m-methylene diphosphonate (99mTc-MDP) single-photon emission computed tomographic (SPECT) scans pre- and posttreatment with cabozantinib and related inhibitors. A consistent reduction in the accumulation of either radiotracer at the site of bone remodeling was observed in animals treated with cabozantinib. Given that cabozantinib is known to inhibit several receptor tyrosine kinases, we drugged animals with various permutations of more selective inhibitors to attempt to refine the molecular basis of bone scan resolution. Neither the vascular endothelial growth factor receptor (VEGFR) inhibitor axitinib, the MET inhibitor crizotinib, nor the combination was capable of inhibiting 18F-NaF accumulation at known bioactive doses. In summary, although the mechanism by which cabozantinib suppresses radionuclide incorporation into foci undergoing bone remodeling remains unknown, that this phenomenon occurs in tumor-naïve models indicates that caution should be exercised in interpreting the clinical significance of this event.

Clinical outcomes of local and metastatic testicular sex cord-stromal tumors.

PURPOSE: We evaluated pathological variables of testicular sex cord-stromal tumors, management options and clinical outcomes. MATERIALS AND METHODS: We retrospectively reviewed the records of 48 patients with testicular sex cord-stromal tumors treated at Memorial Sloan-Kettering Cancer Center between 1997 and 2012. Clinical outcomes were compared based on treatment and previously described pathological factors associated with metastatic potential. RESULTS: Of the 48 patients 37 underwent surveillance without retroperitoneal lymph node dissection, including 34 with no high risk feature and 3 with 1. Median followup was 14.5 months (IQR 6.9-32.5). No patient experienced recurrence. Retroperitoneal lymph node dissection was performed in 11 patients, including 6 with clinical stage I disease and 2 or more high risk features who underwent early dissection, 2 with clinical stage IIa disease at diagnosis who underwent early dissection and 3 with clinical stage I disease and 2 or more high risk features who were observed elsewhere but referred to our institution due to retroperitoneal disease. Six patients with clinical stage I disease underwent early dissection, 4 had no evidence of disease at a median followup of 6.6 years and 2 experienced recurrence and died of disease. Neither of the 2 patients with IIa disease at diagnosis experienced relapse. All 3 patients with delayed dissection experienced relapse and 1 died of disease. CONCLUSIONS: Patients with testicular sex cord-stromal tumors and 1 or no high risk feature can be safely observed without retroperitoneal lymph node dissection but longer followup is needed. Given the lack of effective alternative treatments, early retroperitoneal lymph node dissection may be beneficial in those with 2 or more high risk features, or clinical stage IIa disease.

ERG activates a stem-like proliferation-differentiation program in prostate epithelial cells with mixed basal-luminal identity.

To gain insight into how ERG translocations cause prostate cancer, we performed single cell transcriptional profiling of an autochthonous mouse model at an early stage of disease initiation. Despite broad expression of ERG in all prostate epithelial cells, proliferation was enriched in a small, stem-like population with mixed-luminal basal identity (called intermediate cells). Through a series of lineage tracing and primary prostate tissue transplantation experiments, we find that tumor initiating activity resides in a subpopulation of basal cells that co-express the luminal genes Tmprss2 and Nkx3.1 (called BasalLum) but not in the larger population of classical Krt8+ luminal cells. Upon ERG activation, BasalLum cells give rise to the highly proliferative intermediate state, which subsequently transitions to the larger population of Krt8+ luminal cells characteristic of ERG-positive human cancers. Furthermore, this proliferative population is characterized by an ERG-specific chromatin state enriched for NFkB, AP-1, STAT and NFAT binding, with implications for TF cooperativity. The fact that the proliferative potential of ERG is enriched in a small stem-like population implicates the chromatin context of these cells as a critical variable for unmasking its oncogenic activity.

Paclitaxel, Ifosfamide, and Cisplatin as Initial Salvage Chemotherapy for Germ Cell Tumors: Long-Term Follow-Up and Outcomes for Favorable- and Unfavorable-Risk Disease.

PURPOSE: Paclitaxel, ifosfamide, and cisplatin (TIP) is an established salvage regimen for germ cell tumors (GCT) on the basis of a phase II trial, but efficacy on a large patient cohort including patients with unfavorable risk features and long-term outcomes has not been reported. Herein, we report updated treatment efficacy and long-term follow-up with TIP. PATIENTS AND METHODS: Patients with GCT who received TIP after cisplatin-based chemotherapy were eligible. Favorable response (complete response or partial response with negative tumor markers), overall survival (OS) and progression-free survival (PFS) rates, relapse, and toxicity were determined. Disease was reclassified according to the International Prognostic Factor Study Group (IPFSG) score. RESULTS: Of the 104 patients, 87 had favorable risk factors and 17 had at least one unfavorable factor by Memorial Sloan Kettering Cancer Center (MSKCC) criteria. Ten patients were treated for a second gonadal primary GCT. With a median follow-up of 8.9 years, the 5-year PFS and OS rates were 66% (95% CI, 55 to 74) and 69% (95% CI, 59 to 77), respectively. Among 87 patients with favorable-risk disease, 69 (79%) achieved a favorable response with 5-year PFS and OS rates of 67% (95% CI, 56 to 76) and 72% (95% CI, 61 to 80), respectively. Among 17 patients with MSKCC unfavorable-risk disease, 13 (76%) achieved a favorable response with 5-year PFS and OS rates of 59% (95% CI, 33 to 78) and 56% (95% CI, 28 to 76), respectively. After IPFSG reclassification, 5-year PFS and OS rates for patients with ≤intermediate-risk disease were 75% (95% CI, 50 to 89) and 73% (95% CI, 55 to 85), respectively. CONCLUSION: TIP is an effective second-line regimen for patients with GCT. Similar outcomes were observed in patients with favorable- and unfavorable-risk disease. The randomized TIGER trial (ClinicalTrials.gov identifier: NCT02375204) comparing TIP with high-dose chemotherapy will determine the optimal second-line treatment approach.

Long-term Outcomes of Regressed or "Burnt Out" Primary Testicular Germ Cell Tumors.

OBJECTIVE: To review the presentation and long-term oncologic outcomes of patients with regressed ("burnt out") primary testicular germ cell tumors (GCT). Certain testicular GCT can present with complete regression of the primary tumor. It is not well established if this is associated with more aggressive disease or worse oncologic outcomes. METHODS: We queried our prospectively maintained testicular cancer clinical database at a tertiary cancer center and identified patients without prior chemotherapy who had regressed primary GCT at radical orchiectomy from 1990 to 2023. All specimens were reviewed by a genitourinary pathologist at diagnosis. Long-term clinical outcomes were reported by Kaplan-Meier method. RESULTS: Fifty-six patients met inclusion criteria; at diagnosis, 17 had no evidence of extra-testicular disease and 39 had advanced (clinical stage [CS] II+) GCT. All CSx (no viable disease or germ cell neoplasia in situ at orchiectomy, and no evidence of advanced disease) and CS0 patients were managed with surveillance and had 5-year recurrence-free survival (RFS) of 88% (95% CI: 39%, 98%). All patients with CS II+ disease underwent primary treatment with surgery (n = 5) or first-line chemotherapy (n = 34). Two- and 5-year RFS for patients with CSII+ disease was 94% (95% CI: 78%, 98%) and 90% (95% CI: 72%, 97%), respectively. CONCLUSION: Patients with regressed primary testicular GCT often present with advanced disease, possibly due to lack of early clinical signs from the primary tumor. Our analysis shows excellent long-term oncologic outcomes similar to those reported in the literature for patients with viable primary testicular GCT.

Impact of age on clinicopathological outcomes and recurrence-free survival after the surgical management of nonseminomatous germ cell tumour.

UNLABELLED: Study Type - Therapy (case series) Level of Evidence 4. What's known on the subject? and What does the study add? The effect of advancing age on the clinicopathological outcomes of men with germ cell testicular cancers remains uncertain. Through the review and comparison of the present large cohort of men with testis cancer, we report on our experience in men aged ≥50 years. Our results showed similar clinical and pathological characteristics, and survival outcomes that compare favourably with those of men aged <50 years. OBJECTIVE: To determine the impact of age on clinicopathological findings and disease recurrence in men with nonseminomatous germ cell tumour (NSGCT) undergoing retroperitoneal lymph node dissection (RPLND). PATIENTS AND METHODS: We identified 1246 patients with NSGCT who underwent either primary or post-chemotherapy-RPLND (PC-RPLND) between 1989 and 2006 from our prospective testis cancer database. • Perioperative characteristics were compared among men aged < or ≥50 years. • Multivariable models were used to evaluate the association of age with disease-free survival, controlling for established clinical and pathological features. RESULTS: Of 514 men undergoing primary and 732 men undergoing PC-RPLND, 12 (2.3%) and 23 (3.1%) were aged ≥50 years, respectively. • There were no significant differences between men aged < or ≥50 years for perioperative clinicopathological characteristics, with the exception of pre-RPLND CT nodal size. • The pathological distributions at primary RPLND were similar in men aged < or ≥50 years. After PC-RPLND, there were no differences in RPLND histology, number of lymph nodes resected, estimated blood loss, hospital stay, or perioperative complication rate. • Age at surgery was not a significant predictor of disease recurrence when subjected to a multivariable analysis. CONCLUSIONS: Our data suggests that age at RPLND does not predict for disease recurrence and men aged ≥50 years had similar pre- and postoperative characteristics to those aged <50 years. • We conclude that RPLND can be safely performed in men aged ≥50 years and these patients should be offered optimal treatment regimens for NSGCT as directed according to established guidelines.

Postchemotherapy surgery for germ cell tumors of the testis.

PURPOSE OF REVIEW: To summarize the surgical management of metastatic germ cell tumors of the testis, highlighting the indications for surgery and controversies surrounding the integration of surgery. RECENT FINDINGS: The multidisciplinary approach to the management of germ cell tumors of the testis has resulted in survival rates of greater than 90% overall. However, controversies exist regarding the surgical management of patients who achieve a complete radiographic response following chemotherapy as well as the appropriate retroperitoneal templates to use in the postchemotherapy setting. Recent data have demonstrated that despite a complete radiographic response, approximately 30% of patients will harbor either viable cancer or teratoma in the retroperitoneum. With advances in nerve-sparing techniques and the probability of disease extending beyond the anatomic boundaries of modified templates, a bilateral nerve-sparing retroperitoneal lymph node dissection is the treatment of choice for patients with metastatic nonseminoma, initially treated with chemotherapy. SUMMARY: Postchemotherapy surgical resection of all sites of residual disease remains a critical component to the multidisciplinary management of metastatic testicular cancer.

Defining the therapeutic selective dependencies for distinct subtypes of PI3K pathway-altered prostate cancers.

Previous studies have suggested that PTEN loss is associated with p110ß signaling dependency, leading to the clinical development of p110ß-selective inhibitors. Here we use a panel pre-clinical models to reveal that PI3K isoform dependency is not governed by loss of PTEN and is impacted by feedback inhibition and concurrent PIK3CA/PIK3CB alterations. Furthermore, while pan-PI3K inhibition in PTEN-deficient tumors is efficacious, upregulation of Insulin Like Growth Factor 1 Receptor (IGF1R) promotes resistance. Importantly, we show that this resistance can be overcome through targeting AKT and we find that AKT inhibitors are superior to pan-PI3K inhibition in the context of PTEN loss. However, in the presence of wild-type PTEN and PIK3CA-activating mutations, p110α-dependent signaling is dominant and selectively inhibiting p110α is therapeutically superior to AKT inhibition. These discoveries reveal a more nuanced understanding of PI3K isoform dependency and unveil novel strategies to selectively target PI3K signaling nodes in a context-specific manner.

Author Correction: Aberrant ERG expression cooperates with loss of PTEN to promote cancer progression in the prostate.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Oncogenic ERG Represses PI3K Signaling through Downregulation of IRS2.

Genomic rearrangements leading to the aberrant expression of ERG are the most common early events in prostate cancer and are significantly enriched for the concomitant loss of PTEN. Genetically engineered mouse models reveal that ERG overexpression alone is not sufficient to induce tumorigenesis, but combined loss of PTEN results in an aggressive invasive phenotype. Here, we show that oncogenic ERG repressed PI3K signaling through direct transcriptional suppression of IRS2, leading to reduced RTK levels and activity. In accordance with this finding, ERG-positive human prostate cancers had a repressed AKT gene signature and transcriptional downregulation of IRS2. Although overexpression of IRS2 activated PI3K signaling, promoting cell migration in a PI3K-dependent manner, this did not fully recapitulate the phenotype seen with loss of PTEN as PI3K signaling is not as robust as observed in the setting of loss of PTEN. Importantly, deletions of the PTEN locus, which promotes active PI3K signaling, were among the most significant copy-number alterations that co-occurred with ERG genomic rearrangements. This work provides insight on how initiating oncogenic events may directly influence the selection of secondary concomitant alterations to promote oncogenic signaling during tumor evolution. SIGNIFICANCE: This work provides insight on how initiating oncogenic events may directly influence the selection of secondary concomitant alterations to promote tumorigenesis.

Adjuvant Chemotherapy With Etoposide Plus Cisplatin for Patients With Pathologic Stage II Nonseminomatous Germ Cell Tumors.

PURPOSE: The relapse rate after primary retroperitoneal lymph node dissection (RPLND) for patients with pathologic stage (PS) IIA nonseminomatous germ cell tumors (NSGCTs) is 10%-20% but increases to ≥ 50% for PS IIB disease. We report our experience with 2 cycles of adjuvant etoposide plus cisplatin (EP×2) after therapeutic primary RPLND. PATIENTS AND METHODS: All patients with PS II NSGCT seen at Memorial Sloan Kettering Cancer Center from March 1989 to April 2016 and who were planned to receive EP×2 were included. Each cycle consisted of cisplatin 20 mg/m2 and etoposide 100 mg/m2 on days 1 through 5 at 21-day intervals. Demographic characteristics, histopathologic features, therapeutic and survival outcomes were recorded. RESULTS: Of 156 patients, 30 (19%) had pathologic N1, 122 (78%) had pathologic N2 (pN2), and 4 (3%) had pathologic N3 (pN3) disease. The median number of involved lymph nodes was 3 (range, 1-37 nodes), and the median size of the largest involved node was 2.0 cm (range, 0.4-7.0 cm); extranodal extension was present in 69 patients (45%). Embryonal carcinoma was the most frequent RPLND histology, present in 143 patients (92%). One hundred fifty patients (96%) received EP×2, five received EP×1 and one received EP×4. With a median follow-up of 9 years, 2 patients (1.3%; 1 patient each with pN2 and pN3 disease) experienced relapse; both patients remain continuously disease free at more than 5 and 22 years after salvage chemotherapy. Three patients died, all unrelated to NSGCT, yielding 10-year disease-specific, relapse-free, and overall survival rates of 100%, 98%, and 99%, respectively. CONCLUSION: Adjuvant EP×2 for PS II NSGCT is highly effective, has acceptable toxicity, and incurs less drug cost than 2 cycles of bleomycin, etoposide, and cisplatin. Inclusion of bleomycin in this setting is not necessary.

Tumor Microenvironment-Derived NRG1 Promotes Antiandrogen Resistance in Prostate Cancer.

Despite the development of second-generation antiandrogens, acquired resistance to hormone therapy remains a major challenge in treating advanced prostate cancer. We find that cancer-associated fibroblasts (CAFs) can promote antiandrogen resistance in mouse models and in prostate organoid cultures. We identify neuregulin 1 (NRG1) in CAF supernatant, which promotes resistance in tumor cells through activation of HER3. Pharmacological blockade of the NRG1/HER3 axis using clinical-grade blocking antibodies re-sensitizes tumors to hormone deprivation in vitro and in vivo. Furthermore, patients with castration-resistant prostate cancer with increased tumor NRG1 activity have an inferior response to second-generation antiandrogen therapy. This work reveals a paracrine mechanism of antiandrogen resistance in prostate cancer amenable to clinical testing using available targeted therapies.