Tumor Frameshift Mutation Proportion Predicts Response to Immunotherapy in Mismatch Repair‐Deficient Prostate Cancer

Background: Genomic biomarkers that predict response to anti-PD1 therapy in prostate cancer are needed. Frameshift mutations are predicted to generate more neoantigens than missense mutations; therefore, we hypothesized that the number or proportion of tumor frameshift mutations would correlate with response to anti-PD1 therapy in prostate cancer. Methods: To enrich for response to anti-PD1 therapy, we assembled a multicenter cohort of 65 men with mismatch repair-deficient (dMMR) prostate cancer. Patient characteristics and outcomes were determined by retrospective chart review. Clinical somatic DNA sequencing was used to determine tumor mutational burden (TMB), frameshift mutation burden, and frameshift mutation proportion (FSP), which were correlated to outcomes on anti-PD1 treatment. We subsequently used data from a clinical trial of pembrolizumab in patients with nonprostatic dMMR cancers of various histologies as a biomarker validation cohort. Results: Nineteen of 65 patients with dMMR metastatic castration-resistant prostate cancer were treated with anti-PD1 therapy. The PSA50 response rate was 65%, and the median progression-free survival (PFS) was 24 (95% confidence interval 16-54) weeks. Tumor FSP, more than overall TMB, correlated most strongly with prolonged PFS and overall survival (OS) on anti-PD1 treatment and with density of CD8+ tumor-infiltrating lymphocytes. High FSP similarly identified patients with longer PFS as well as OS on anti-PD1 therapy in a validation cohort. Conclusion: Tumor FSP correlated with prolonged efficacy of anti-PD1 treatment among patients with dMMR cancers and may represent a new biomarker of immune checkpoint inhibitor sensitivity. Implications for practice: Given the modest efficacy of immune checkpoint inhibition (ICI) in unselected patients with advanced prostate cancer, biomarkers of ICI sensitivity are needed. To facilitate biomarker discovery, a cohort of patients with DNA mismatch repair-deficient (dMMR) prostate cancer was assembled, as these patients are enriched for responses to ICI. A high response rate to anti-PD1 therapy in these patients was observed; however, these responses were not durable in most patients. Notably, tumor frameshift mutation proportion (FSP) was identified as a novel biomarker that was associated with prolonged response to anti-PD1 therapy in this cohort. This finding was validated in a separate cohort of patients with nonprostatic dMMR cancers of various primary histologies. This works suggests that FSP predicts response to anti-PD1 therapy in dMMR cancers, which should be validated prospectively in larger independent cohorts

MEND Syndrome: A case report with scanning electron microscopy findings of the collodion membrane

Made available in DSpace on 2017-04-13T23:51:39Z (GMT). No. of bitstreams: 1 LuisSuita.pdf: 652947 bytes, checksum: 74b29e5b2acbd02ee1a4d701d46af6bd (MD5) Previous issue date: 2017-03-02201

The mutational landscape of metastatic castration-sensitive prostate cancer : the spectrum theory revisited

BackgroundEmerging data suggest that metastasis is a spectrum of disease burden rather than a binary state, and local therapies, such as radiation, might improve outcomes in oligometastasis. However, current definitions of oligometastasis are solely numerical.ObjectiveTo characterize the somatic mutational landscape across the disease spectrum of metastatic castration-sensitive prostate cancer (mCSPC) to elucidate a biological definition of oligometastatic CSPC.Design, setting, and participantsThis was a retrospective study of men with mCSPC who underwent clinical-grade sequencing of their tumors (269 primary tumor, 25 metastatic sites). Patients were classified as having biochemically recurrent (ie, micrometastatic), metachronous oligometastatic (≤5 lesions), metachronous polymetastatic (>5 lesions), or de novo metastatic (metastasis at diagnosis) disease.Outcome measurements and statistical analysisWe measured the frequency of driver mutations across metastatic classifications and the genomic associations with radiographic progression-free survival (rPFS) and time to castrate-resistant prostate cancer (CRPC).Results and limitationsThe frequency of driver mutations in TP53 (p =  0.01), WNT (p =  0.08), and cell cycle (p =  0.04) genes increased across the mCSPC spectrum. TP53 mutation was associated with shorter rPFS (26.7 vs 48.6 mo; p =  0.002), and time to CRPC (95.6 vs 155.8 mo; p =  0.02) in men with oligometastasis, and identified men with polymetastasis with better rPFS (TP53 wild-type, 42.7 mo; TP53 mutated, 18.5 mo; p =  0.01). Mutations in TP53 (incidence rate ratio [IRR] 1.45; p =  0.004) and DNA double-strand break repair (IRR 1.61; p <  0.001) were associated with a higher number of metastases. Mutations in TP53 were also independently associated with shorter rPFS (hazard ratio [HR] 1.59; p =  0.03) and the development of CRPC (HR 1.71; p =  0.01) on multivariable analysis. This study was limited by its retrospective nature, sample size, and the use of commercially available sequencing platforms, resulting in a limited predefined set of genes examined.ConclusionsSomatic mutational profiles reveal a spectrum of metastatic biology that helps in redefining oligometastasis beyond a simple binary state of lesion enumeration.Patient summaryOligometastatic prostate cancer is typically defined as less than three to five metastatic lesions and evidence suggests that using radiation or surgery to treat these sites improves clinical outcomes. As of now, treatment decisions for oligometastasis are solely defined according to the number of lesions. However, this study suggests that tumor mutational profiles can provide a biological definition of oligometastasis and complement currently used numerical definitions

Association of the Time to Immune Checkpoint Inhibitor (ICI) Initiation and Outcomes With Second Line ICI in Patients With Advanced Urothelial Carcinoma

Background: Early progression on first-line (1L) platinum-based therapy or between therapy lines may be a surrogate of more aggressive disease and poor outcomes in advanced urothelial carcinoma (aUC), but its prognostic role regarding immune checkpoint inhibitor (ICI) response and survival is unclear. We hypothesized that shorter time until start of second-line (2L) ICI would be associated with worse outcomes in aUC. Patients and Methods: We performed a retrospective multi-institution cohort study in patients with aUC treated with 1L platinum-based chemotherapy, who received 2L ICI. Patients receiving switch maintenance ICI were excluded. We defined time to 2L ICI therapy as the time between the start of 1L platinum-based chemotherapy to the start of 2L ICI and categorized patients a priori into 1 of 3 groups: less than 3 months versus 3-6 months versus more than 6 months. We calculated overall response rate (ORR) with 2L ICI, progression-free survival (PFS) and overall survival (OS) from the start of 2L ICI. ORR was compared among the 3 groups using multivariable logistic regression, and PFS, OS using cox regression. Multivariable models were adjusted for known prognostic factors. Results: We included 215, 215, and 219 patients in the ORR, PFS, and OS analyses, respectively, after exclusions. ORR difference did not reach statistical significance between patients with less than 3 months versus 3-6 months versus more than 6 months to 2L ICI. However, PFS (HR 1.64; 95% CI 1.02-2.63) and OS (HR 1.77; 95% CI 1.10-2.84) was shorter among those with time to 2L ICI less than 3 months compared to those who initiated 2L ICI more than 6 months. Conclusion: Among patients with aUC treated with 2L ICI, time to 2L ICI less than 3 months was associated with lower, but not significantly different ORR, but shorter PFS and OS compared to 2L ICI more than 6 months. This highlights potential cross resistance mechanisms between ICI and platinum-based chemotherapy

Histological Subtypes and Response to PD-1/PD-L1 Blockade in Advanced Urothelial Cancer: A Retrospective Study

PURPOSE: Urinary tract cancer can be pure urothelial carcinoma, pure nonurothelial carcinoma or variant urothelial carcinoma (defined here as mixed urothelial carcinoma). Little is known regarding outcomes for patients with variant urothelial carcinoma receiving immune checkpoint inhibitors. We hypothesized that variant urothelial carcinoma does not compromise immune checkpoint inhibitor efficacy in patients with advanced urothelial carcinoma. MATERIALS AND METHODS: We performed a retrospective cohort study across 18 institutions. Demographic, clinicopathological, treatment and outcomes data were collected for patients with advanced urothelial carcinoma who received immune checkpoint inhibitors. Patients were divided into pure vs variant urothelial carcinoma subgroups, with variant urothelial carcinoma further divided by type of variant (ie squamous, neuroendocrine etc). We compared overall response rate using univariate and multivariate logistic regression and progression-free survival and overall survival using Kaplan-Meier and univariate and multivariate Cox proportional hazards. RESULTS: Overall 519 patients were identified, with 395, 406 and 403 included in overall response rate, overall survival and progression-free survival analyses, respectively. Overall response rate to immune checkpoint inhibitors between patients with pure vs variant urothelial carcinoma was comparable (28% vs 29%, p=0.90) without significant differences for individual subtypes vs pure urothelial carcinoma. Median overall survival for patients with pure urothelial carcinoma was 11.0 months vs 10.1 months for variant urothelial carcinoma (p=0.60), but only 4.6 months for patients with neuroendocrine features (9 patients, HR 2.75, 95% CI 1.40-5.40 vs pure urothelial carcinoma, p=0.003). Median progression-free survival was 4.1 months for pure vs 5.2 months for variant urothelial carcinoma (p=0.43) and 3.7 months for neuroendocrine features (HR 1.87, 95% CI 0.92-3.79 vs pure urothelial carcinoma, p=0.09). CONCLUSIONS: Overall response rate to immune checkpoint inhibitors was comparable across histological types. However, overall survival was worse for patients with tumors containing neuroendocrine features. Variant urothelial carcinoma should not exclude patients from receiving immune checkpoint inhibitors