Optimizing the treatment of metastatic castration-resistant prostate cancer: a Latin America perspective

Prospective Study of Homologous Recombination Repair Gene Mutation Prevalence in Patients With Advanced Prostate Cancer From Latin America: Challenges and Future Approaches

PURPOSE

The prevalence of homologous recombination repair gene mutations (HRRm) in patients with metastatic castration-resistant prostate cancer (mCRPC) in Latin America and the Caribbean (LAC) is unknown. Prevalence of homologous Recombination repair (HRR) gene mutatiOns in patientS with metastatic castration resistant ProstatE Cancer in LaTin America (PROSPECT) aimed to determine this prevalence and to describe the demographic and clinical characteristics of the participants.

MATERIALS AND METHODS

This was a prospective, cross-sectional, multicenter study across 11 cancer centers in seven LAC countries. After informed consent, all eligible participants underwent genomic testing by provided blood samples for germline HRR testing; they also provided PC tissue blocks if available for somatic HRR testing.

RESULTS

Between April 2021 and April 2022, 387 patients (median age, 70 years [49-89], 94.3% Eastern Cooperative Oncology Group 0-1) with mCRPC were enrolled in the study. Almost 40% of them had a family history of cancer, and the overall time from their initial PC and mCRPC diagnosis was 3 years and 1 year, respectively. The overall prevalence of germline HRRm was 4.2%. The mutations detected included the genes CHEK2 (n = 4, 1%), ATM (n = 3, 0.8%), BRCA2 (n = 3, 0.8%), BRIP1 (n = 2, 0.5%), RAD51B (n = 2, 0.5%), BRCA1 (n = 1, 0.3%), and MRE11 (n = 1, 0.3%). The prevalence of somatic HRRm could not be assessed because of high HRR testing failure rates (79%, 199/251) associated with insufficient DNA, absence of tumor cells, and poor-quality DNA.

CONCLUSION

Despite the study's limitations, to our knowledge, PROSPECT was the first attempt to describe the prevalence of HRRm in patients with PC from LAC. Notably, the germline HRRm prevalence in this study was inferior to that observed in North American and European populations. The somatic HRR testing barriers identified are being addressed by several projects to improve access to HRR testing and biomarker-based therapies in LAC.

AR-V7 as a Biomarker for Resistance to Treatment with Abiraterone/Enzalutamide in Three Latin American Countries: A Hypothetical Cost-Saving Analysis

BACKGROUND

Prostate cancer is the most incident and one of the deadliest male cancers in Latin America. Treatment for patients with metastatic castration-resistant prostate cancer (mCRPC) includes androgen receptor signaling inhibitors such as abiraterone and enzalutamide, for which androgen receptor splice variant 7 (AR-V7) has emerged as a biomarker for primary resistance. Our study sought to analyze the potential economic impact of the use of AR-V7 detection as a treatment indicator in patients with mCRPC in three Latin American countries.

MATERIALS AND METHODS

A hypothetical cost prediction model for the use of noninvasive circulating tumor cell-based AR-V7 testing as a treatment indicator for patients eligible for treatment with abiraterone/enzalutamide was conducted using available information on treatment and testing costs from Mexico, Argentina, and Colombia.

RESULTS

At an estimated prevalence of AR-V7 positivity of 20%, the use of upfront AR-V7 genetic testing resulted in annual net savings of $9,801,669.97, $6,390,055.75, and $3,096,780.91 in Mexico, Argentina, and Colombia, respectively. A direct relationship between AR-V7 positivity prevalence and net savings was found.

CONCLUSION

The use of a noninvasive AR-V7 detection assay as a treatment indicator tool in patients eligible for treatment with abiraterone or enzalutamide in Latin America could be a cost-effective approach for the management of these patients. Additional efforts are needed to accurately determine the incidence of castration-resistant prostate cancer cases and the prevalence of AR-V7 positivity in Latin America in order to predict the potential economic benefit of its clinical use.

IMPLICATIONS FOR PRACTICE

In Latin America, prostate cancer is the most frequently diagnosed cancer in men, and the burden of this disease is expected to double in this region by 2030. Noninvasive detection of androgen receptor splice variant 7 (AR-V7) is being currently validated as a predictive biomarker for benefit with androgen receptor signaling inhibitor therapy in patients with metastatic castration-resistant prostate cancer (mCRPC). This hypothetical cost-saving analysis shows that AR-V7 testing in peripheral blood of patients with CRPC eligible for treatment with abiraterone or enzalutamide might represent a cost-effective strategy to select patients who will benefit from AR-axis-directed treatment in three Latin American countries.

Feasibility and efficacy of sequential systemic therapy for metastatic castration-resistant prostate cancer in a rural health care setting

Aim: The aim of this study was to evaluate the feasibility and efficacy, in terms of overall survival, of sequential systemic therapy in patients with metastatic castration-resistant prostate cancer (MCRPC) who lived in Nordland County, Norway, a large region with a challenging geography, yet only one department of oncology located in the main city, Bodø.Patients and methods: Overall 77 patients who had received at least 2 lines of treatment were included in this retrospective study.Results: Management included docetaxel in 69 patients (90%), often prescribed in first line. Only 12 patients (16%) started their treatment with a sequence of two endocrine drugs (enzalutamide or abiraterone acetate). Thirty-two patients (42%) were not eligible for treatment beyond second line, while 31 (40%) received 3 lines, and 14 (18%) more than 3 lines (for example cabazitaxel or Ra-223). Distance to the department of oncology did not predict for treatment with more than 2 lines. Only two factors were statistically significant: age <75 years and not initiating treatment with two lines of endocrine drugs. Survival increased with increasing number of lines of treatment. None of the five individual drugs available to these patients was significantly associated with survival.Conclusions: There was no indication toward under-treatment with systemic therapy among patients from the distant regions. Sequential treatment was feasible and survival increased with each additional line.

Cancer mortality predictions for 2019 in Latin America

We estimated mortality figures for 2019 in seven Latin American countries, with focus on breast cancer. We retrieved cancer death certification and population data from the WHO and PAHO databases. We obtained mortality statistics for Argentina, Brazil, Chile, Colombia, Cuba, Mexico and Venezuela for 1970-2015. We predicted current death numbers and age-standardised (world population) mortality rates using joinpoint regression models. Total cancer mortality is predicted to decline in all countries and both sexes, except Argentinian women. Cuba had the highest all cancer rates for 2019, 136.9/100,000 men and 90.4 women, while Mexico showed the lowest ones, 63.8/100,000 men and 61.9 women. Stomach cancer showed favourable trends over the whole period, while colorectal cancer only recently. Lung cancer rates declined in men, while in women they decreased slightly over the most recent years, only. In Cuban women, lung cancer rates overtook breast cancer ones. Breast cancer showed overall favourable trends, but rates are rising in young women. Prostate and uterine cancer had favourable trends. Pancreas, ovary, bladder and leukaemias showed slightly decreasing trends. Between 1990 and 2019, mortality from all neoplasms is predicted to fall by about 18% in Argentina, 26% in Chile, 14% in Colombia, 17% in Mexico and 13% in Venezuela, corresponding to almost 0.5 million avoided cancer deaths. No decline was observed in Brazil and Cuba. Of concern, the persisting high rates of (cervix) uterus cancer, the high lung cancer rates in Cuba, the possible increases in breast cancer in young women, and the lack of overall declines in Brazil, Cuba and Venezuelan men.