Plasma AR and abiraterone-resistant prostate cancer
Alessandro Romanel, Delila Gasi Tandefelt, Vincenza Conteduca, Anuradha Jayaram, Nicola Casiraghi, Daniel Wetterskog, Samanta Salvi, Dino Amadori, Zafeiris Zafeiriou, Pasquale Rescigno, Diletta Bianchini, Giorgia Gurioli, Valentina Casadio, Suzanne Carreira, Jane Goodall, Anna Wingate, Roberta Ferraldeschi, Nina Tunariu, Penny Flohr, Ugo De Giorgi, Johann S de Bono, Francesca Demichelis, Gerhardt Attard, Alessandro Romanel, Delila Gasi Tandefelt, Vincenza Conteduca, Anuradha Jayaram, Nicola Casiraghi, Daniel Wetterskog, Samanta Salvi, Dino Amadori, Zafeiris Zafeiriou, Pasquale Rescigno, Diletta Bianchini, Giorgia Gurioli, Valentina Casadio, Suzanne Carreira, Jane Goodall, Anna Wingate, Roberta Ferraldeschi, Nina Tunariu, Penny Flohr, Ugo De Giorgi, Johann S de Bono, Francesca Demichelis, Gerhardt Attard
Abstract
Androgen receptor (AR) gene aberrations are rare in prostate cancer before primary hormone treatment but emerge with castration resistance. To determine AR gene status using a minimally invasive assay that could have broad clinical utility, we developed a targeted next-generation sequencing approach amenable to plasma DNA, covering all AR coding bases and genomic regions that are highly informative in prostate cancer. We sequenced 274 plasma samples from 97 castration-resistant prostate cancer patients treated with abiraterone at two institutions. We controlled for normal DNA in patients' circulation and detected a sufficiently high tumor DNA fraction to quantify AR copy number state in 217 samples (80 patients). Detection of AR copy number gain and point mutations in plasma were inversely correlated, supported further by the enrichment of nonsynonymous versus synonymous mutations in AR copy number normal as opposed to AR gain samples. Whereas AR copy number was unchanged from before treatment to progression and no mutant AR alleles showed signal for acquired gain, we observed emergence of T878A or L702H AR amino acid changes in 13% of tumors at progression on abiraterone. Patients with AR gain or T878A or L702H before abiraterone (45%) were 4.9 and 7.8 times less likely to have a ≥50 or ≥90% decline in prostate-specific antigen (PSA), respectively, and had a significantly worse overall [hazard ratio (HR), 7.33; 95% confidence interval (CI), 3.51 to 15.34; P = 1.3 × 10(-9)) and progression-free (HR, 3.73; 95% CI, 2.17 to 6.41; P = 5.6 × 10(-7)) survival. Evaluation of plasma AR by next-generation sequencing could identify cancers with primary resistance to abiraterone.
Conflict of interest statement
Competing interests
The Institute of Cancer Research developed abiraterone and therefore has a commercial interest in this agent. G.A. is on the ICR list of rewards to inventors for abiraterone. J.S.d.B. has received consulting fees and travel support from Amgen, Astellas, AstraZeneca, Boehringer Ingelheim, Bristol-Myers Squibb, Dendreon, Enzon, Exelixis, Genentech, GlaxoSmithKline, Medivation, Merck, Novartis, Pfizer, Roche, Sanofi-Aventis, Supergen and Takeda, and grant support from AstraZeneca and Genentech. G.A. has received honoraria, consulting fees or travel support from Astellas, Medivation, Janssen, Millennium Pharmaceuticals, Ipsen, Ventana and Sanofi-Aventis, and grant support from Janssen, AstraZeneca and Arno. The other authors do not declare any competing interests.
Copyright © 2015, American Association for the Advancement of Science.
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Source: PubMed