A cohort study evaluating the clinical, environmental and genetic profiles of men with early-onset, aggressive prostate cancer

266

Background: The frequency of young men with aggressive prostate cancer (PC) at diagnosis is increasing. Clinical, environmental, and genetic drivers of this change have not been well characterized. Methods: This multi-institutional study evaluated two cohorts; Cohort 1 completed enrollment and is reported here. Eligible patients (pts) had early-onset (age ≤ 60 years) PC with metastasis (N+ or M+) at diagnosis, or within 5 years of curative intent local therapy. Data were collected to define clinical, environmental, and genetic profiles, including ctDNA and whole genome and transcriptome sequencing using Tempus xE. Standard descriptive statistics were used. Results: 46 pts were enrolled. Median age at diagnosis was 55 (range 41-60 years); 85% were White, 15% were Black; 4% served in the military and 4% reported biochemical exposure. 85% reported a family history of cancer, 46% had family history of PC. Median PSA at diagnosis was 19 (range 1-534 ng/mL), 56% had a Gleason score of 9-10, and 56% had de novo metastatic PC. 46% had prior local therapy. Genetic data is available for 40 pts. The most frequent clinically significant mutations (≥10% for somatic, ≥2.5% for germline) are summarized. 23 unique germline and over 1,000 unique somatic mutations were identified. Germline mutations associated with hereditary PC were found in 15%, all were associated with DNA damage repair (DDR). Somatic mutations in DDR genes were found in 10%. Co-mutations in TP53 and BRAF were seen in 30%. Interestingly, there were also incidental germline mutations identified that are associated with cardiac ( MYBPC, MYH7) and vascular ( MYH11, ACTA2) conditions, among others. Conclusions: In this cohort study we identified an unexpectedly high frequency of family histories that were positive for cancer (85%), and specifically PC (46%). However, rates of germline mutations associated with hereditary PC were similar to previous studies (15%), suggesting the possibility that other novel hereditary mutations driving increased PC risk may be present. Increased rates of somatic mutations in BRAF (35%) were also seen. The high frequency of BRAF mutations, particularly those that co-occur with TP53 mutations, may be driving more aggressive disease. We also found enrichment of mutations associated with non-cancer hereditary syndromes, including hypertrophic cardiomyopathy. These are not usually included in cancer-focused genetic studies, suggesting broader testing that includes potentially actionable incidental findings should be considered. More work is needed to define characteristics of this high-risk population and optimize management. [Table: see text]

Clinical, environmental, genetic, and genomic profile of men with early-onset aggressive prostate cancer

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Background: Although prostate cancer (PC) is heterogeneous, the rate of patients diagnosed with aggressive metastatic disease at a young age has been increasing. Prior studies defining genetic abnormalities in high-risk PC have not focused on this unique population of patients, thus the clinical and molecular features of these lethal PC phenotypes are not well described. Methods: This multi-institutional study evaluated two cohorts. Cohort 1, reported here, included early-onset (age ≤ 60) PC that was metastatic (N+ or M+) at diagnosis or PC that metastasized within 5 years post curative intent/local therapy. Cohort 2 included men with metastatic hormone sensitive PC who rapidly progressed (≤ 14 months) after systemic therapy. Data was collected to define clinical and genomic profiles, including sequencing of somatic & germline DNA, circulating tumor DNA and tumor RNA. Standard descriptive statistics were used. Results: 44 patients were enrolled. Median age at diagnosis was 55 years (range 41-60); 84% were White and 14% were Black. Median prostate specific antigen at diagnosis was 20 (range 1-534 ng/mL). 54% reported a family history of PC, while breast and colorectal cancer were reported in 35% and 14%, respectively. 4.5% reported a history of biochemical agent exposure. 58.5% of patients had De Novo distant metastatic disease (56% of these were low-volume) and 59.5% had a Gleason score of 9-10. 59% had received prior local therapy. Germline and somatic genetic data are available for 36 patients (4 are pending). The most common somatic mutation was in TP53 (n=15), followed by BRAF (n=14), AR (n=7), ERBB3 & MYC (n=5 each), CDKN2B, HRAS, MUC4, OBSCN & SPOP (n=4 each). Additional unique mutations in over 1,000 genes were also identified. Germline mutations were detected in BRCA2, ATM, ATP7B & FBN1 (n=3 each), RB1, CDH1, MYBPC3, MYH11 & MYH7 (n=2 each). 11 other unique germline mutations were also identified. Germline mutations were identified in genes previously implicated in hereditary PC ( BRCA2, ATM, PALB2, BRIP1 & CHEK2), with an overall germline incidence of 25%. There were also incidental germline mutations in genes related to hereditary cardiac conditions ( MYBPC, MYH11, MYH7), as well as other hereditary cancers ( RB1 and CDH1). Conclusions: This study evaluated specific criteria to define risk factors associated with the development of aggressive PC at a young age. Nearly 90% of these patients had a family history of cancer, with over 50% reporting a family history of PC. Somatic mutations were identified in genes such as TP53 that are frequently associated with aggressive disease. Additionally, there was enrichment for germline mutations associated with PC that exceeded what has previously been reported and enrichment of mutations not commonly included in PC genetic risk panels. Thus, more work is needed to define characteristics of this high-risk population and optimize management.

A phase II study of sEphB4-HSA in metastatic castration-resistant prostate cancer

84

Background: Ephrin receptors and their membrane-localized ligands induce bidirectional signaling and facilitate tumor-stroma interactions. Expression of EphB4 is increased in prostate cancer tissue and cell lines and retained in castration resistant states, and can promote cell migration, invasion, and metastases. Blocking the EphB4-EphrinB2 pathway, which can be accomplished by soluble EphB4 conjugated to human serum albumin (sEphB4-HSA), has efficacy in preclinical models of aggressive prostate cancer. A phase I clinical trial of sEphB4-HSA led to response or stable disease in 56% of patients, with no grade 4 or 5 related adverse events, and combination pembrolizumab sEphB4-HSA led to a 52% response rate in EphrinB2 expressing urothelial cancer. We hypothesized that targeting the EphB4-EphrinB2 pathway may serve as a therapeutic target in the treatment of metastatic castration resistant prostate cancer (mCRPC). Methods: We conducted a single arm, phase II trial in patients with progressive mCRPC and treatment with at least one second generation androgen receptor (AR)-targeted therapy but no more than three prior therapies for mCRPC. On Day 1 of each cycle patients received sEphB4-HSA 1000 mg IV, with cycle length 14 days cycles 1-6 and cycle length 21 days for cycle 7 and beyond. The primary endpoint was confirmed prostate specific antigen (PSA) response rate (confirmed decrease in PSA by > 50%). We employed a Simon two stage Minimax design, requiring two or more responses among the first 15 patients to enroll an additional ten patients. Results: Fourteen eligible patients enrolled in the study. Median age was 73.5 years (range 52-83), patients had a median baseline PSA value of 65.11 ng/mL (range 7.77-2850 ng/mL) and received a median of three prior therapies (range 1-3) for mCRPC. Ten patients received prior taxane for mCRPC or hormone sensitive prostate cancer. The median length of treatment with sEphB4-HSA was 6.5 weeks (range 2-35 weeks). The potentially treatment-related adverse events (AEs) that occurred in more than 25% of patients were hypertension (10 patients) and fatigue (7 patients). Three patients experienced a serious adverse event potentially related to therapy, including one patient with a grade 5 event (cerebral vascular accident) possibly related to study drug. No patient had a confirmed PSA response, and the study was stopped for futility. Thirteen patients had PSA progression ( > 25% increase in PSA), and one patient withdrew due to toxicity prior to having an evaluable PSA response. The median time to PSA progression was 28 days (95% CI 28-64 days), and median time to radiologic progression was 55 days (95% CI 55 days-NR). Of three patients with measurable disease, two had stable disease and one had progressive disease. Conclusions: In patients with mCRPC who progressed on prior second generation AR-targeted therapy, sEphB4-HSA monotherapy had no discernable anti-tumor activity. Clinical trial information: NCT04033432.

Correlation of pathologic findings after brief neoadjuvant sorafenib (neoS) with results of dynamic-contrast enhanced (DCE) and diffusion-weighted (DW) magnetic resonance imaging (MRI) in patients (pts) with locally advanced or metastatic clear cell renal cell carcinoma (RCC)

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Background: Many pts receiving tyrosine kinase inhibitors for RCC manifest stable disease as their best response by RECIST criteria. We hypothesized that tumor necrosis by DCE and DW-MRI after brief treatment with neoS may correlate with pathologic findings. We investigated in a pilot study whether these MRI changes may serve as an imaging biomarker predictive of clinical outcome. Methods: Pts with locally advanced or metastatic clear cell RCC undergoing nephrectomy or metastastectomy were treated with neoS 400mg PO bid for 28 days prior to surgery. The feasibility and safety of neoS was determined. Tumor necrosis detected by DCE and DW MRI’s pre- and post-neoS were compared and correlated with survival and pathologic findings at surgery. RECIST/WHO criteria were also compared. Results: 9 pts were enrolled, and all underwent surgery after neoS, 4 weeks (n=7) or less for toxicity (n=2). Clear cell/sarcomatoid histology was noted in 8 pts, and papillary in 1. All pts had T3 or T4 disease. 7 had M1 disease. No surgical complications occurred. 7 pts (78%) experienced Grade 3 toxicities, including hypertension (n=1), pancreatitis (n=1), hand-foot syndrome (n=1), hyponatremia (n=2), and rash (n=2). No grade 4 or 5 toxicities were observed. 4 of 8 clear cell/sarcomatoid pts (50%) have died, 3 due to progressive disease and 1 of unrelated causes. DCE and DW MRI’s with direct surgical pathological correlation were available in 7 of these pts. The mean ADC DW MRI changes in the renal lesion of 4 longer term survivors (median survival = 43 months) was +.22 vs. –0.07 in the 3 short term survivors (median survival = 13 months). RECIST/WHO criteria did not correlate with response. Evaluation of lack of enhancement on DCE MRI and increase in ADC on DW MRI were seen and correlated with necrosis on pathologic specimens. Conclusions: Four weeks of neoS is associated with significant necrosis that correlates with DCE-MRI and DW-MRI. There may be a trend in survival with greater necrosis, suggesting a role for these imaging biomarkers to assess early benefits of therapy. Clinical trial information: NCT00727532.

A phase I study of high-dose calcitriol in combination with temozolomide for patients (Pts) with metastatic melanoma (MM)

9087

Background: Temozolomide (Tem) has demonstrated efficacy as an oral alternative for pts with MM on traditional and extended dosing schedules. Calcitriol has known antiproliferative properties in vitro, and has shown synergistic effects with chemotherapy. Additionally, vitamin D receptor (VDR) polymorphisms are associated with alterations in melanoma susceptibility and disease progression. Specifically, the VDR genotype tt/ff (Taq1 and Fok1 polymorphisms) has been associated with tumors >3.5mm, though no studies have focused on survival. Methods: Tem 150mg/m2was administered on days 2-8 and 16-22 every 28 days until progression or significant toxicity. Calcitriol was given on days 1 and 15 every 28 days with 3 pts at a dose of 0.2mcg/kg, 3 pts at 0.3mcg/kg, 3 pts at 0.5mcg/kg, and an additional 11 pts at a maximum dose of 0.5mcg/kg. VDR gene analysis was completed on 17/20 pts using PCR-RFLP based assays. Tolerability was the primary objective with secondary objectives of time to progression (PFS) and overall survival (OS), both as a whole and by VDR genotype. Results: Twenty pts (males=15) with MM treated with at least one prior systemic therapy or who were not candidates for interleukin-2 (conducted pre BRAF and anti CTLA agents), were accrued. Median age was 58. The regimen was well-tolerated with leukopenia, lymphopenia, thrombocytopenia, anemia, and thrombosis as the most common grade 3 or 4 toxicities at 10% incidence each, less than observed in prior studies (Patel et al Eur J Ca 2011). Obj RR was 10%. Median PFS was 1.8 mo with a mean of 2.7 cycles given. Pts with low-risk VDR genotype non-tt or ff (n= 11) had a median OS of 7.4 mo compared to 3.8 mo for tt or ff or both (n=6)(median ratio=1.95) from time of enrollment, although not statistically significant given small sample sizes. Conclusions: The extended dosing of Tem with calcitriol is a well-tolerated oral regimen in MM. The trend toward improved OS in non-tt/ff VDR genotypes is consistent with prior studies associating the tt/ff genotype with biologic aggressiveness. Whether this represents a benefit of the inclusion of calcitriol should be studied further. Clinical trial information: NCT00301067.

Correlation of pathologic findings after brief neoadjuvant sorafenib with results of dynamic-contrast enhanced (DCE) and diffusion-weighted magnetic resonance imaging (DW-MRI) in patients with locally advanced or metastatic clear cell renal cell carcinoma (RCC)

466

Background: Many pts receiving tyrosine kinase inhibitors for RCC manifest stable disease as their best response by RECIST criteria. We hypothesized that tumor necrosis by DCE and DW-MRI after brief treatment with neoS may correlate with pathologic findings. We investigated in a pilot study whether these MRI changes may serve as an imaging biomarker predictive of clinical outcome. Methods: Pts with locally advanced or metastatic clear cell RCC undergoing nephrectomy or metastastectomy were treated with neoS 400mg PO bid for 28 days prior to surgery. The feasibility and safety of neoS was determined. Tumor necrosis detected by DCE and DW MRI’s pre- and post-neoS were compared and correlated with survival and pathologic findings at surgery. RECIST/WHO criteria were also compared. Results: 9 pts were enrolled, and all underwent surgery after neoS, 4 weeks (n=7) or less for toxicity (n=2). Clear cell/sarcomatoid histology was noted in 8 pts, and papillary in 1. All pts had T3 or T4 disease. 7 had M1 disease. No surgical complications occurred. 7 pts (78%) experienced grade 3 toxicities, including hypertension (n=1), pancreatitis (n=1), hand-foot syndrome (n=1), hyponatremia (n=2), and rash (n=2). No grade 4 or 5 toxicities were observed. 4 of 8 clear cell/sarcomatoid pts (50%) have died, 3 because of progressive disease and 1 of unrelated causes. DCE and DW MRI’s with direct surgical pathological correlation were available in 7 of these pts. The mean ADC DW MRI changes in the renal lesion of 4 longer term survivors (median survival = 43 months) was +.22 vs. –0.07 in the 3 short term survivors (median survival = 13 months). RECIST/WHO criteria did not correlate with response. Evaluation of lack of enhancement on DCE MRI and increase in ADC on DW MRI were seen and correlated with necrosis on pathologic specimens. Conclusions: Four weeks of neoS is associated with significant necrosis that correlates with DCE-MRI and DW-MRI. There may be a trend in survival with greater necrosis, suggesting a role for these imaging biomarkers to assess early benefits of therapy. Clinical trial information: NCT00727532.