Investigators have identified genomic alterations that appear to be associated with prognosis in men with metastatic castration-sensitive prostate cancer (mCSPC).

Astudy of 424 patients with mCSPC treated at a tertiary care center revealedthat alterations in the androgen receptor (AR), TP53, cell-cycle, MYC oncogenicsignaling pathways occur more commonly in tumors with worse overall survivaland decreased time to castration-resistant disease, whereas alterations in theSPOP and MNT pathways occur more frequently in tumors with a better prognosis,according to findings published in ClinicalCancer Research.

Thegenomics of metastatic castration-sensitive prostate cancer have not been wellcharacterized in the literature, but it is now clear that upfront treatmentintensification with taxanes or next-generation AR-directed therapies offerbenefit in the overall patient population, said the studys co-senior authorWassim Abida, MD, a medical oncologist at Memorial Sloan Kettering CancerCenter in New York. The question remains whether treatment selection ortargeted therapies can be employed based on genomic characteristics.

Theassociation between alterations in cell-cycle genes and TP53 and MYC pathwaygenes and worse outcomes may pave the way for targeted therapy in thesehigher-risk groups, Dr Abida said.

Thestudy compared genomic alterations according to clinical phenotypes: high- vslow-volume disease and de novo vsmetastatic recurrence. Of the 424 patients in the study, 213 men (50%) hadhigh-volume disease (4 or more bone metastases or visceral metastases) and 211(50%) had low-volume disease; 65% had de novometastases and 35% had metastatic recurrence. At the time of sample collection, patients had a medianage of 66 years. The investigators conducted gene sequencing from May 2015 to September2018.

High- vs low-volume disease

Inadjusted analyses, men with higher-volume disease had significant 1.8- and3.7-fold increased risks of castration-resistant disease and death,respectively, compared with men who had low-volume disease. Tumor specimensfrom men with high-volume disease had more copy number alterations.

Amongmen with high-volume disease, the highest-ranking pathways were the NOTCH,cell-cycle, and epigenetic modifiers pathways.

Althoughthe prevalence of CDK12 alterations differed between patients with de novo metastatic and those with metastaticrecurrences, the groups had similar prognoses. I was actually surprised therewere not more dramatic genomic differences between de novo and relapsed disease, said study co-senior author PhilipKantoff, MD, a medical oncologist and Chair of the Department of Medicine atMemorial Sloan Kettering Cancer Center in New York.

Afteradjusting for disease volume and other genomic pathways, the researchers foundthat the rates of castration resistance differed by 1.5-fold and up to 5-fold accordingto alterations in the AR, SPOP (inverse), TP53, cell-cycle, WNT (inverse), andMYC pathways. Overall survival (OS) rates varied from 2- to 4-fold according toalterations in the AR, SPOP (inverse), WNT (inverse), and cell-cycle pathways.PI3K pathway alterations were not associated with prognosis.

Docetaxeland next-generation AR axis-directed therapies have been shown to prolong OS, butit remains uncertain which patients benefit the most from intensifiedtherapies. We did not find any obvious genomic reason to explain thedifferences in docetaxel sensitivity between high- and low-volume disease, DrKantoff said.

Theauthors pointed out that genomic landscape studies of tumor DNA profiling inprostate cancer in general have excluded metastatic castration-sensitive tumors.Instead, most studies have focus on localized disease or metastaticcastration-resistant disease.

DrAbida and his colleagues acknowledged that their study has inherent biases becauseit was hospital based and enrolled patients at an academic referral center.

Moleculardeterminants of castration resistance or survival in patients with mHSPC have beenunclear, but the new study sheds new light on molecular alterations associatedwith poor outcomes in men with mHSPC, particularly alterations in the AR, cellcycle genes, MYC, and TP53 genes, said Joshi Alumkal, MD, the Leader of theProstate/Genitourinary Medical Oncology Section and Associate Division Chieffor Basic Research in the Hematology-Oncology Division at the University ofMichigan School of Medicine.

Severalrandomized phase 3 clinical trials now show a benefit of escalating treatmentin men with mHSPC by adding novel AR-targeting agents or chemotherapy plusmedical castration versus medical castration alone, Dr Alumkal said. Whetherthe addition of any of these specific agents to medical castration isassociated with improved outcomes in patients with poor-risk molecularalterations identified by the new study is a critical next question, he said.

Urologiconcologist James Mohler, MD, Senior Vice President for Translational Researchat Roswell Park Comprehensive Cancer Center in Buffalo, New York, said the new study found relativelysmall differences among the clinical phenotypes, but that is not surprisingbecause the temporal differences in the evolution of tumor biology occur overlong periods of time, much of which precedes clinical presentation. The hazardratios for association between mutational analysis and oncologic outcome insome cases were statistically significant, but are so small as to not beclinically significant. Part of the reason for this may be that prostatecancer, once metastatic, is so complex that no single mutation or single genepathway is driving growth and hence targetable at a high rate beyond the long provenbenefit from androgen deprivation therapy, Dr Mohler said.

The results reported by these authors may be disappointing to many clinicians, but are important because they represent a comprehensive analysis of mCSPC. The authors appropriately acknowledge that better tumor sampling and more comprehensive genetic analysis and larger numbers of patients may be required to find any benefit to genomic or somatic sequencing, Dr Mohler said. I am afraid that these limitations are not just of their work but a biological limitation of aggressive prostate cancer, which makes improving treatment of advanced prostate cancer in an individual patient extremely challenging.

Reference

Stopsack KH, Nandakumar S, Wibmer AG, et al. Oncogenic genomic alterations, clinical phenotypes, and outcomes in metastatic castration-sensitive prostate cancer [published online March 27, 2020]. Clin Cancer Res. doi: 10.1158/1078-0432.CCR-20-0168

This article originally appeared on Renal and Urology News

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