Brandon David Bernard

Impact of EGFR point mutations on the sensitivity to gefitinib : Insights from comparative structural analyses and molecular dynamics simulations

Emergence of resistant mutations in drug targets represents a serious problem in the targeted chemotherapy. One challenging issue is to understand the atomic‐detailed effect of the mutation on the target. Another intriguing issue is how to predict specific mutations that would show up in the clinical setting, leading to drug resistance. By computational approaches, we have investigated structural, dynamics and energetic effects of a series of EGFR mutations identified from the lung cancer patients. We demonstrated mutation L858R caused gefitinib move closer to the hinge region, whereas T790M caused the ligand escape from the binding pocket. In particular, the T790M decreased the size of the hydrophobic slot formed by L718 and G796. This suggests that, to be effective against the T790M mutant, the inhibitors should avoid interactions with the hydrophobic slot. Mutations T790M, L858R, and their combinations are found to cause different conformational redistribution and to perturb the electrostatic potential at the ATP‐binding pocket. Normal mode analysis revealed the mutations resulted in changes in the correlated movements in the protein. In an attempt to develop a computational descriptor for predicting the functional effect of EGFR mutations, we have developed a Plarm algorithm, and the Plarm score was found to be an excellent predictor of the functional impact of six clinical relevant mutations in EGFR tyrosine kinase domains, including T790M, L858R, G719C, L861Q, T790M + L858R double mutant, and delL747–P753insS. The Plarm algorithm could be readily extended to investigate other drug targets. Proteins 2006.

Genomic evolution and chemoresistance in germ-cell tumours

Germ-cell tumours (GCTs) are derived from germ cells and occur most frequently in the testes. GCTs are histologically heterogeneous and distinctly curable with chemotherapy. Gains of chromosome arm 12p and aneuploidy are nearly universal in GCTs, but specific somatic genomic features driving tumour initiation, chemosensitivity and progression are incompletely characterized. Here, using clinical whole-exome and transcriptome sequencing of precursor, primary (testicular and mediastinal) and chemoresistant metastatic human GCTs, we show that the primary somatic feature of GCTs is highly recurrent chromosome arm level amplifications and reciprocal deletions (reciprocal loss of heterozygosity), variations that are significantly enriched in GCTs compared to 19 other cancer types. These tumours also acquire KRAS mutations during the development from precursor to primary disease, and primary testicular GCTs (TGCTs) are uniformly wild type for TP53. In addition, by functional measurement of apoptotic signalling (BH3 profiling) of fresh tumour and adjacent tissue, we find that primary TGCTs have high mitochondrial priming that facilitates chemotherapy-induced apoptosis. Finally, by phylogenetic analysis of serial TGCTs that emerge with chemotherapy resistance, we show how TGCTs gain additional reciprocal loss of heterozygosity and that this is associated with loss of pluripotency markers (NANOG and POU5F1) in chemoresistant teratomas or transformed carcinomas. Our results demonstrate the distinct genomic features underlying the origins of this disease and associated with the chemosensitivity phenotype, as well as the rare progression to chemoresistance. These results identify the convergence of cancer genomics, mitochondrial priming and GCT evolution, and may provide insights into chemosensitivity and resistance in other cancers.

Uterine adenosarcomas: A dual-institution update on staging, prognosis and survival

OBJECTIVE Uterine adenosarcomas (AS) are rare tumors thought to have a favorable prognosis. The aim of this study was to evaluate clinicopathological characteristics and treatment outcome in women with uterine AS. METHODS Patients with uterine AS were identified from the institutional databases at two regional cancer centers, Princess Margaret Hospital, Toronto and Vancouver General Hospital. All cases underwent specialist pathological review and were re-staged according to FIGO criteria (2009). Patient demographics, treatment data and outcomes were evaluated. RESULTS Between 1984 and 2010, 64 patients with confirmed AS were identified: 30 exhibited sarcomatous overgrowth (AS+SO). 47 patients presented with stage I disease: 27 IA and 18 IB. 57 of the 58 patients with known surgical management underwent hysterectomy: 55 having bilateral salpingo-oophorectomy, 12 having lymph node dissection. 14 patients received adjuvant treatment: 10 radiotherapy, 3 chemotherapy and 1 both. Sixteen of the 45 patients (35.6%) with follow-up recurred; median time to recurrence 21.2 months, range 2.1-87.8 months. Recurrence was associated with myometrial invasion (p=0.05). Two of the 10 women (20%) with AS+SO receiving adjuvant treatment recurred compared to 9 of the 14 (64%) who did not. One of the 5 women (20%) with stage IB disease who received adjuvant treatment recurred (20%) compared to 6 of the 7 (85.6%) who did not. CONCLUSIONS Long term surveillance is required given the variable time to recurrence. For those with AS+SO and myometrial invasion adjuvant treatment should be considered and further investigation of adjuvant strategies is warranted.

Conditional Survival of Patients With Metastatic Testicular Germ Cell Tumors Treated With First-Line Curative Therapy

PURPOSE The International Germ Cell Cancer Collaborative Group (IGCCCG) criteria prognosticate survival outcomes in metastatic testicular germ cell tumor (MT-GCT), but how the initial risk changes over time for those who survived since curative treatment is unknown. PATIENTS AND METHODS We assessed patients eligible for first-line therapy for MT-GCT at five tertiary cancer centers from 1990 to 2012 for 2-year conditional overall survival (COS) and conditional disease-free survival (CDFS), defined as the probability of surviving, or surviving and being disease free, respectively, for an additional 2 years at a given time point since the initial diagnosis. RESULTS For all patients (N = 942), 2-year COS increased from 92% (95% CI, 91% to 94%) at 0 months to 98% (95% CI, 97% to 99%), and 2-year CDFS increased from 83% (95% CI, 81% to 86%) at baseline to 98% (95% CI, 97% to 99%) at 24 months after diagnosis. Two-year COS improved by 2% (97% at 0 months, 99% at 24 months) in the IGCCCG favorable-risk group, by 5% (94% at 0 months, 99% at 24 months) in the intermediate-risk group, and by 22% (71% at 0 months to 93% at 24 months) in the poor-risk group. Two-year CDFS improved significantly at 12 months for each risk group (favorable, 91% baseline v 95% at 12 months; intermediate, 84% v 95%; poor, 55% v 85%). Baseline IGCCCG risk stratification was not associated with long-term COS or CDFS for patients who survived to greater than 2 years post therapy. No significant differences in COS and CDFS were noted between seminoma and nonseminoma; patients ≥ 40 years old had inferior 2-year COS from 0 to 12 months, but no differences were noted at 18 months. CONCLUSION Our data suggest that the concept of conditional survival applies to patients with MT-GCT treated with curative therapy. Patients with MT-GCT who survived and remained disease free more than 2 years after the diagnosis had an excellent chance of staying alive and disease free in additional subsequent years, regardless of the initial IGCCCG risk stratification.

Insurance status and disparities in disease presentation, treatment, and outcomes for men with germ cell tumors.

People aged 26 to 34 years represent the greatest proportion of the uninsured, and they have the highest incidence of testicular cancers. The aim of this study was to investigate the association between insurance status and cancer outcomes in men diagnosed with germ cell tumors.

Impact of ethnicity on the outcome of men with metastatic, hormone-sensitive prostate cancer

Prostate cancer (PCa) outcomes are impacted by socioeconomic and biologic factors. Ethnicity plays a role in the former, but little is known about the responsiveness of metastatic PCa to androgen‐deprivation therapy (ADT) among races.

Approach to Oligometastatic Prostate Cancer.

Oligometastatic prostate cancer has increasingly been recognized as a unique clinical state with therapeutic implications. It has been proposed that patients with oligometastases may have a more indolent course and that outcome may be further improved with metastasis-directed local ablative therapy. In addition, there are differing schools of thoughts regarding whether oligometastases represent isolated lesions-where targeted therapy may render a patient disease free-or whether they coexist with micrometastases, where targeted therapy in addition to systemic therapy is required for maximal clinical impact. As such, the approach to the patient with oligometastatic prostate cancer requires multidisciplinary consideration, with surgery, radiotherapy, and systemic therapy potentially of benefit either singularly or in combination. Indeed, mounting evidence suggests durable disease-free intervals and, in some cases, possibly cure, may be achieved with such a multimodal strategy. However, selecting patients that may benefit most from treatment of oligometastases is an ongoing challenge. Moreover, with the advent of new, highly sensitive imaging technologies, the spectrum based on CT of the abdomen and pelvis and technetium bone scan of localized to oligometastatic to widespread disease has become increasingly blurred. As such, new MRI- and PET-based modalities require validation. As some clinical guidelines advise against routine prostate-specific antigen screening, the possibility of more men presenting with locally advanced or de novo oligometastatic prostate cancer exists; thus, knowing how best to treat these patients may become more relevant at a population level. Ultimately, the arrival of prospective clinical data and better understanding of biology will hopefully further inform how best to treat men with this disease.

Age ≥40 Years Is Associated with Adverse Outcome in Metastatic Germ Cell Cancer Despite Appropriate Intended Chemotherapy

BACKGROUND Age ≥40 yr is associated with poorer testicular cancer outcomes in population-based studies. OBJECTIVE To assess the association between age (≥40 yr) and outcomes among men with germ cell tumors (GCTs) in a large hospital registry. DESIGN, SETTING, AND PARTICIPANTS Electronic medical records for 1095 GCT patients treated at Dana-Farber Cancer Institute between 1997 and 2013 were reviewed. Information regarding histology, stage, treatment, and patient characteristics was obtained. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS Using logistic regression analysis and Cox proportional hazards regression, we investigated the association between age and treatment and risk of relapse and GCT-specific death for men with GCT. RESULTS AND LIMITATIONS At diagnosis, 26% of men (n=283/1095) were ≥40 yr. Among the 610 men with clinical stage 1 (CS1) disease, age ≥40 yr was not associated with a higher risk of CS1 relapse (hazard ratio [HR] 1.19, 95% confidence interval [CI] 0.74-1.92). There were 603 men with metastatic disease (CS1 at diagnosis with subsequent relapse or metastasis at diagnosis); after adjusting for stage and histology, men ≥40 yr were more likely to receive etoposide and cisplatin chemotherapy compared to bleomycin, etoposide, and cisplatin as their primary treatment (odds ratio 2.40, 95% CI 1.14-5.05). Salvage therapy also differed by age. In the multivariable model, men ≥40 yr with metastatic GCT had a higher risk of relapse (HR 1.58, 95% CI 1.02-2.46) after primary treatment and death from GCT (HR 2.31, 95% CI 1.29-4.15). The study limitations include incomplete data on medical comorbidities and possible subsequent dose modifications. CONCLUSIONS Men aged ≥40 yr with metastatic GCT have poorer outcomes, even after accounting for different intended treatment patterns. PATIENT SUMMARY In this study we looked at the outcome for testicular cancer in more than 1000 patients treated at a single institution in the USA. We found that the treatment for metastatic disease differed between older (≥40 yr) and younger patients. Furthermore, outcomes for older patients (≥40 yr) were worse than for younger men.

Questioning the Value of Fluorodeoxyglucose Positron Emission Tomography for Residual Lesions After Chemotherapy for Metastatic Seminoma: Results of an International Global Germ Cell Cancer Group Registry

PURPOSE Residual lesions after chemotherapy are frequent in metastatic seminoma. Watchful waiting is recommended for lesions < 3 cm as well as for fluorodeoxyglucose (FDG) positron emission tomography (PET)-negative lesions ≥ 3 cm. Information on the optimal management of PET-positive residual lesions ≥ 3 cm is lacking. PATIENTS AND METHODS We retrospectively identified 90 patients with metastatic seminoma with PET-positive residual lesions after chemotherapy. Patients with elevated α-fetoprotein or nonseminomatous histology were excluded. We analyzed the post-PET management and its impact on relapse and survival and calculated the positive predictive value (PPV) for PET. RESULTS Median follow-up time was 29 months (interquartile range [IQR], 10 to 62 months). Median diameter of the largest residual mass was 4.9 cm (range, 1.1 to 14 cm), with masses located in the retroperitoneum (77%), pelvis (16%), mediastinum (17%), and/or lung (3%). Median time from the last day of chemotherapy to PET was 6.9 weeks (IQR, 4.4 to 9.9 weeks). Post-PET management included repeated imaging in 51 patients (57%), resection in 26 patients (29%), biopsy in nine patients (10%) and radiotherapy in four patients (4%). Histology of the resected specimen was necrosis in 21 patients (81%) and vital seminoma in five patients (19%). No biopsy revealed vital seminoma. Relapse or progression occurred in 15 patients (17%) after a median of 3.7 months (IQR, 2.5 to 4.9 months) and was found in 11 (22%) of 51 patients on repeated imaging, in two (8%) of 26 patients after resection, and in two (22%) of nine patients after biopsy. All but one patient who experienced relapse were successfully treated with salvage therapy. The PPV for FDG-PET was 23%. CONCLUSION FDG-PET has a low PPV for vital tumor in residual lesions after chemotherapy in patients with metastatic seminoma. This cautions against clinical decisions based on PET positivity alone.

Smoking and Disease Outcomes in Patients With Malignant Germ Cell Tumors

Background To our knowledge, no studies have evaluated the association between smoking and stage at diagnosis or survival among men with germ cell tumors (GCTs). We therefore evaluated the association between smoking and GCT presentation and outcomes. Methods Electronic medical records of 1161 patients with GCT treated at Dana‐Farber Cancer Institute between 1997 and 2013 were reviewed. Outcomes of interest were stage at diagnosis, relapse from clinical stage I (CSI) disease, relapse after first‐line chemotherapy, and death from disease. Logistic regression models evaluated the association between smoking and tumor characteristics at diagnosis. Multivariable Cox proportional hazards regression was used to calculate hazard ratios (HRs) and 95% confidence intervals (CIs) for the association between smoking at diagnosis and risk of relapse and GCT cancer death. Results In men diagnosed with CSI disease, smokers were 86% more likely to have a large tumor (≥ 4 cm) compared with nonsmokers (odds ratio [OR] 1.86; 95% CI, 1.28‐2.71) and had a statistically significant increased risk of relapse (HR 2.05; 95% CI, 1.41‐2.97). Among men with metastatic disease at diagnosis, the heaviest smokers (> 15 pack‐years) were more likely to present with intermediate‐ or poor‐risk disease compared with nonsmokers (OR 3.12; 95% CI, 1.29‐7.55) and any smoking was associated with a statistically significant increased risk of relapse (HR 1.86; 95% CI, 1.26‐2.73) and GCT death (HR 2.56; 95% CI, 1.55‐4.23). Conclusion Smoking is associated with more advanced disease at diagnosis and poorer GCT outcomes, including increased risk of relapse, for both CSI and metastatic disease. Micro‐Abstract Electronic medical records of 1161 patients with germ cell tumor (GCT) at Dana‐Farber Cancer Institute were used to evaluate the association between smoking and GCT presentation and outcomes. Smoking was associated with more advanced disease at diagnosis and poorer GCT outcomes, including increased risk of relapse.