End points in clinical trials in diffuse large B-cell lymphoma: time for more dialogue?

We observed lack of clarity and consistency in end point definitions of large randomized clinical trials in diffuse large B-cell lymphoma. These inconsistencies are such that trials might, in fact, address different clinical questions. They complicate interpretation of results, including comparisons across studies. Problems arise from different ways to account for events occurring after randomization including absence of improvement in disease status, treatment discontinuation or the initiation of new therapy. We call for more dialogue between stakeholders to define with clarity the questions of interest and corresponding end points. We illustrate that assessing different end point rules across a range of plausible patient journeys can be a powerful tool to facilitate such a discussion and contribute to better understanding of patient-relevant end points.

What is this article about? This article talks about the lack of clarity and consistency in the definitions of outcomes used in clinical trials that investigate new treatments for diffuse large B-cell lymphoma. This is mainly due to how these different outcome definitions handle events such as absence of improvement in disease status, treatment discontinuation or initiation of new treatment. The authors discuss how these inconsistencies make it hard to interpret the results of individual clinical trials and to compare results across clinical trials.Why is it important? Defining the above events and consequently defining outcomes affects what we can learn from the trials and can lead to different results. Some approaches may not reflect good and bad outcomes for patients appropriately. This makes it challenging for patients, physicians, health authorities and payors to understand the true benefit of treatments under investigation and which one is better.What are the key take-aways? This article serves as a call-to-action for more dialogue among all stakeholders involved in drug development and the decision-making process related to drug evaluations. There is an urgent need for clinical trials to be designed with more clarity and consistency on what is being measured so that relevant questions for patients and prescribing physicians are addressed. Understanding patient journeys will be key to successfully understand what truly matters to patients and how to measure the benefit of new treatments. Such discussions will contribute toward more clarity and consistency in the evaluation of new treatments.

Talazoparib in Patients With Solid Tumors With BRCA1/2 Mutation: Results From the Targeted Agent and Profiling Utilization Registry Study.

PURPOSE: The Targeted Agent and Profiling Utilization Registry Study is a phase II basket trial evaluating the antitumor activity of commercially available targeted agents in patients with advanced cancer and genomic alterations known to be drug targets. Results of a cohort of patients with various solid tumors with germline or somatic BRCA1/2 mutations treated with talazoparib are reported. METHODS: Eligible patients had advanced solid tumors, measurable disease (RECIST), Eastern Cooperative Oncology Group performance status 0-2, adequate organ function, and no standard treatment options. Patients with germline BRCA-mutated human epidermal growth factor receptor 2-negative locally advanced or metastatic breast cancer were not eligible for this study. Primary end point was disease control (DC) determined by investigator assessment of objective response (OR) or stable disease (SD) of at least 16 weeks duration (SD16+). The results were evaluated on the basis of a one-sided exact binomial test with a null DC rate of 15% versus 35% (power = 0.82; α = .10). Secondary end points were OR, progression-free survival, overall survival, duration of response, duration of SD, and safety. RESULTS: Twenty-eight patients (20 cancer types) with BRCA1/2 mutations were enrolled from December 2019 to September 2021 and collapsed into a single histology pooled cohort for analysis. All patients were evaluable for efficacy. One complete response, nine partial response, and six SD16+ were observed for DC and OR rates of 57% (one-sided 90% CI, 43 to 100) and 36% (95% CI, 19 to 56), respectively. The null hypothesis of a 15% DC rate was rejected (P < .001). Patients with OR had the following tumor types: breast (2), nonmelanoma skin, mesothelioma, stomach, uterus, non-small cell lung cancer, ovary, hepatocellular carcinoma, and pancreas. Thirteen patients had at least one grade 3-5 adverse event (AE) or serious AE at least possibly related to talazoparib. All were consistent with the drug label except bilirubin increase and hyponatremia (both grade 3 AEs). CONCLUSION: Talazoparib demonstrated antitumor activity in patients with advanced solid tumors and BRCA1/2 mutations, including cancer types for which poly ADP-ribose polymerase inhibitors are not yet US Food and Drug Administration-approved.

Common variation in a long non-coding RNA gene modulates variation of circulating TGF-ß2 levels in metastatic colorectal cancer patients (Alliance).

BACKGROUND: Herein, we report results from a genome-wide study conducted to identify protein quantitative trait loci (pQTL) for circulating angiogenic and inflammatory protein markers in patients with metastatic colorectal cancer (mCRC). The study was conducted using genotype, protein marker, and baseline clinical and demographic data from CALGB/SWOG 80405 (Alliance), a randomized phase III study designed to assess outcomes of adding VEGF or EGFR inhibitors to systemic chemotherapy in mCRC patients. Germline DNA derived from blood was genotyped on whole-genome array platforms. The abundance of protein markers was quantified using a multiplex enzyme-linked immunosorbent assay from plasma derived from peripheral venous blood collected at baseline. A robust rank-based method was used to assess the statistical significance of each variant and protein pair against a strict genome-wide level. A given pQTL was tested for validation in two external datasets of prostate (CALGB 90401) and pancreatic cancer (CALGB 80303) patients. Bioinformatics analyses were conducted to further establish biological bases for these findings. RESULTS: The final analysis was carried out based on data from 540,021 common typed genetic variants and 23 protein markers from 869 genetically estimated European patients with mCRC. Correcting for multiple testing, the analysis discovered a novel cis-pQTL in LINC02869, a long non-coding RNA gene, for circulating TGF-ß2 levels (rs11118119; AAF = 0.11; P-value < 1.4e-14). This finding was validated in a cohort of 538 prostate cancer patients from CALGB 90401 (AAF = 0.10, P-value < 3.3e-25). The analysis also validated a cis-pQTL we had previously reported for VEGF-A in advanced pancreatic cancer, and additionally identified trans-pQTLs for VEGF-R3, and cis-pQTLs for CD73. CONCLUSIONS: This study has provided evidence of a novel cis germline genetic variant that regulates circulating TGF-ß2 levels in plasma of patients with advanced mCRC and prostate cancer. Moreover, the validation of previously identified pQTLs for VEGF-A, CD73, and VEGF-R3, potentiates the validity of these associations.

Refining Risk Stratification of High-risk and Locoregional Prostate Cancer: A Pooled Analysis of Randomized Trials.

BACKGROUND AND OBJECTIVE: Radiotherapy (RT) and long-term androgen deprivation therapy (ltADT; 18-36 mo) is a standard of care in the treatment of high-risk localized/locoregional prostate cancer (HRLPC). We evaluated the outcomes in patients treated with RT + ltADT to identify which patients have poorer prognosis with standard therapy. METHODS: Individual patient data from patients with HRLPC (as defined by any of the following three risk factors [RFs] in the context of cN0 disease-Gleason score ≥8, cT3-4, and prostate-specific antigen [PSA] >20 ng/ml, or cN1 disease) treated with RT and ltADT in randomized controlled trials collated by the Intermediate Clinical Endpoints in Cancer of the Prostate group. The outcome measures of interest were metastasis-free survival (MFS), overall survival (OS), time to metastasis, and prostate cancer-specific mortality. Multivariable Cox and Fine-Gray regression estimated hazard ratios (HRs) for the three RFs and cN1 disease. KEY FINDINGS AND LIMITATIONS: A total of 3604 patients from ten trials were evaluated, with a median PSA value of 24 ng/ml. Gleason score ≥8 (MFS HR = 1.45; OS HR = 1.42), cN1 disease (MFS HR = 1.86; OS HR = 1.77), cT3-4 disease (MFS HR = 1.28; OS HR = 1.22), and PSA >20 ng/ml (MFS HR = 1.30; OS HR = 1.21) were associated with poorer outcomes. Adjusted 5-yr MFS rates were 83% and 78%, and 10-yr MFS rates were 63% and 53% for patients with one and two to three RFs, respectively; corresponding 10-yr adjusted OS rates were 67% and 60%, respectively. In cN1 patients, adjusted 5- and 10-yr MFS rates were 67% and 36%, respectively, and 10-yr OS was 47%. CONCLUSIONS AND CLINICAL IMPLICATIONS: HRLPC patients with two to three RFs (and cN0) or cN1 disease had the poorest outcomes on RT and ltADT. This will help in counseling patients treated in routine practice and in guiding adjuvant trials in HRLPC. PATIENT SUMMARY: Radiotherapy and long-term hormone therapy are standard treatments for high-risk and locoregional prostate cancer. In this report, we defined prognostic groups within high-risk/locoregional prostate cancer and showed that outcomes to standard therapy are poorest in those with two or more "high-risk" factors or evidence of lymph node involvement. Such patients may therefore be the best candidates for intensification of treatment.

Pertuzumab Plus Trastuzumab in Patients With Biliary Tract Cancer With ERBB2/3 Alterations: Results From the Targeted Agent and Profiling Utilization Registry Study.

PURPOSE: Targeted Agent and Profiling Utilization Registry is a phase II basket trial evaluating the antitumor activity of commercially available targeted agents in patients with advanced cancer and genomic alterations known to be drug targets. Results of a cohort of patients with biliary tract cancer (BTC) with ERBB2/3 amplification, overexpression, or mutation treated with pertuzumab plus trastuzumab are reported. METHODS: Eligible patients had advanced BTC, measurable disease (RECIST v1.1), Eastern Cooperative Oncology Group performance status 0-2, adequate organ function, tumors with ERBB2/3 alterations, and a lack of standard treatment options. Simon's two-stage design was used with a primary end point of disease control (DC), defined as objective response (OR) or stable disease of at least 16+ weeks duration (SD16+) according to RECIST v1.1. Secondary end points included OR, progression-free survival, overall survival, duration of response, duration of stable disease, and safety. RESULTS: Twenty-nine patients were enrolled from February 2017 to January 2022, and all had advanced BTC with an ERBB2/3 alteration. One patient was not evaluable for efficacy. One complete response, eight partial responses, and two SD16+ were observed for DC and OR rates of 40% (90% CI, 27 to 100) and 32% (95% CI, 16 to 52), respectively. The null hypothesis of 15% DC rate was rejected (P = .0015). Four patients had at least one grade 3 adverse event (AE) or serious AE at least possibly related to treatment: anemia, diarrhea, infusion-related reaction, and fatigue. CONCLUSION: Pertuzumab plus trastuzumab met prespecified criteria to declare a signal of activity in patients with BTC and ERBB2/3 amplification, overexpression, or mutation.

Regorafenib in Patients With Solid Tumors With BRAF Alterations: Results From the Targeted Agent and Profiling Utilization Registry (TAPUR) Study.

PURPOSE: Targeted Agent and Profiling Utilization Registry is a phase II basket trial evaluating the antitumor activity of commercially available targeted agents in patients with advanced cancer with genomic alterations known to be drug targets. Results of a cohort of patients with solid tumors with BRAF alterations treated with regorafenib are reported. METHODS: Eligible patients had measurable disease (RECIST v.1.1), Eastern Cooperative Oncology Group performance status 0-1, adequate organ function, and no standard treatment options. The primary end point was disease control (DC), defined as investigator assessment of patients with complete or partial response (PR) or stable disease of at least 16-weeks duration (SD16+). Low accruing histology-specific cohorts with BRAF alterations treated with regorafenib were collapsed into a single histology-pooled cohort for this analysis. The results were evaluated on the basis of a one-sided exact binomial test with a null DC rate of 15% versus 35% (power, 0.84; α, .10). Secondary end points were objective response (OR), progression-free survival, overall survival, duration of response, duration of stable disease, and safety. RESULTS: Twenty-eight patients with 12 tumor types with BRAF alterations were enrolled from June 2016 to June 2021. All patients were evaluable for efficacy. Two patients with PR and four with SD16+ were observed for DC and OR rates of 21% (90% CI, 12 to 100) and 7% (95% CI, 1 to 24), respectively. The null hypothesis of 15% DC rate was not rejected (P = .24). Eight patients had at least one grade 3 adverse event or serious adverse event at least possibly related to regorafenib. CONCLUSION: Regorafenib did not meet prespecified criteria to declare a signal of activity in patients with solid tumors with BRAF alterations.

Current issues in dose-finding designs: A response to the US Food and Drug Adminstration's Oncology Center of Excellence Project Optimus.

With the advent of targeted agents and immunological therapies, the medical research community has become increasingly aware that conventional methods for determining the best dose or schedule of a new agent are inadequate. It has been well established that conventional phase I designs cannot reliably identify safe and effective doses. This problem applies, generally, for cytotoxic agents, radiation therapy, targeted agents, and immunotherapies. To address this, the US Food and Drug Administration's Oncology Center of Excellence initiated Project Optimus, with the goal "to reform the dose optimization and dose selection paradigm in oncology drug development." As a response to Project Optimus, the articles in this special issue of Clinical Trials review recent advances in methods for choosing the dose or schedule of a new agent with an overall objective of informing clinical trialists of these innovative designs. This introductory article briefly reviews problems with conventional methods, the regulatory changes that encourage better dose optimization designs, and provides brief summaries of the articles that follow in this special issue.

Toward Informed Selection and Interpretation of Clinical Genomic Tests in Prostate Cancer.

Clinical genomic testing of patient germline, tumor tissue, or plasma cell-free DNA can enable a personalized approach to cancer management and treatment. In prostate cancer (PCa), broad genotyping tests are now widely used to identify germline and/or somatic alterations in BRCA2 and other DNA damage repair genes. Alterations in these genes can confer cancer sensitivity to poly (ADP-ribose) polymerase inhibitors, are linked with poor prognosis, and can have potential hereditary cancer implications for family members. However, there is huge variability in genomic tests and reporting standards, meaning that for successful implementation of testing in clinical practice, end users must carefully select the most appropriate test for a given patient and critically interpret the results. In this white paper, we outline key pre- and post-test considerations for choosing a genomic test and evaluating reported variants, specifically for patients with advanced PCa. Test choice must be based on clinical context and disease state, availability and suitability of tumor tissue, and the genes and regions that are covered by the test. We describe strategies to recognize false positives or negatives in test results, including frameworks to assess low tumor fraction, subclonal alterations, clonal hematopoiesis, and pathogenic versus nonpathogenic variants. We assume that improved understanding among health care professionals and researchers of the nuances associated with genomic testing will ultimately lead to optimal patient care and clinical decision making.

Pharmacogenetic and clinical risk factors for bevacizumab-related gastrointestinal hemorrhage in prostate cancer patients treated on CALGB 90401 (Alliance).

The objective of this study was to discover clinical and pharmacogenetic factors associated with bevacizumab-related gastrointestinal hemorrhage in Cancer and Leukemia Group B (Alliance) 90401. Patients with metastatic castration-resistant prostate cancer received docetaxel and prednisone ± bevacizumab. Patients were genotyped using Illumina HumanHap610-Quad and assessed using cause-specific risk for association between single nucleotide polymorphisms (SNPs) and gastrointestinal hemorrhage. In 1008 patients, grade 2 or higher gastrointestinal hemorrhage occurred in 9.5% and 3.8% of bevacizumab (n = 503) and placebo (n = 505) treated patients, respectively. Bevacizumab (P < 0.001) and age (P = 0.002) were associated with gastrointestinal hemorrhage. In 616 genetically estimated Europeans (n = 314 bevacizumab and n = 302 placebo treated patients), grade 2 or higher gastrointestinal hemorrhage occurred in 9.6% and 2.0% of patients, respectively. One SNP (rs1478947; HR 6.26; 95% CI 3.19-12.28; P = 9.40 × 10-8) surpassed Bonferroni-corrected significance. Grade 2 or higher gastrointestinal hemorrhage rate was 33.3% and 6.2% in bevacizumab-treated patients with the AA/AG and GG genotypes, versus 2.9% and 1.9% in the placebo arm, respectively. Prospective validation of these findings and functional analyses are needed to better understand the genetic contribution to treatment-related gastrointestinal hemorrhage.

Prognostic and predictive analyses of circulating plasma biomarkers in men with metastatic castration resistant prostate cancer treated with docetaxel/prednisone with or without bevacizumab.

BACKGROUND: CALGB 90401 (Alliance) was a phase III trial of 1050 patients with metastatic castration-resistant prostate cancer (mCRPC) comparing docetaxel, prednisone, bevacizumab (DP+B) versus DP alone. While this trial did not show an improvement in overall survival (OS), there were improved intermediate outcomes suggesting that subsets of men may derive benefit from this combination. The purpose of this analysis was to identify prognostic and predictive biomarkers associated with OS and progression-free survival (PFS) benefit from DP+B. METHODS: Baseline EDTA plasma samples from 650 consenting patients were analyzed for 24 biomarkers. The proportional hazards model was utilized to test for the prognostic and predictive importance of the biomarkers for OS. The statistically significant biomarkers of OS were further investigated for prognostic and predictive importance for other secondary outcomes. RESULTS: 15 markers [ICAM-1, VEGF-R3, TIMP-1, TSP-2, Ang-2, Her-3, Osteopontin (OPN), PlGF, VCAM-1, HGF, VEGF, Chromogranin A, IL-6, VEGF-R1, BMP-9] were prognostic of OS, while 9 markers (ICAM-1, VEGF-R3, Her-3, TIMP-1, Ang-2, OPN, PlGF, HGF, and VEGF) were also prognostic of PFS. All markers were statistically significant in univariate analyses after adjustment for multiplicity (FDR < 0.1). In multivariable analyses of OS adjusting for risk score, seven markers had FDR < 0.1, including ICAM-1, VEGF-R3, TIMP-1, Ang-2, VEGF, TSP-2 and HGF. In unadjusted analysis, OPN was predictive of PFS improvement with DP+B, in both univariate and multivariable analysis. However, none of the biomarkers tested were predictive of clinical outcomes after adjusting for multiple comparisons. CONCLUSIONS: Multiple biomarkers were identified in CALGB 90401 as prognostic of clinical outcomes but not predictive of OS. While OPN may have promise as a potential biomarker for anti-angiogenic therapies, further mechanistic and clinical studies are needed to determine the underlying biology and potential clinical application.

Updated 5-year results for short course abiraterone acetate and LHRH agonist for unfavorable intermediate and favorable high-risk prostate cancer.

Combined androgen deprivation therapy (ADT) and radiotherapy (RT) improves outcomes for intermediate and high-risk prostate cancer. Treatment intensification with abiraterone acetate/prednisone (AAP) provides additional benefit for high-risk disease. We previously reported 3-year outcomes of a single-arm prospective multicenter trial (AbiRT trial) of 33 patients with unfavorable intermediate risk (UIR) and favorable high risk (FHR) prostate cancer undergoing short course, combination therapy with ADT, AAP, and RT. Here we report the final analysis demonstrating a high rate of testosterone recovery (97%) and excellent biochemical progression-free survival (97%) at 5 years. These data support comparative prospective studies of shorter, more potent ADT courses in favorable high-risk prostate cancer.

Sunitinib in Patients With Breast Cancer With FGFR1 or FGFR2 Amplifications or Mutations: Results From the Targeted Agent and Profiling Utilization Registry Study.

PURPOSE: The Targeted Agent and Profiling Utilization Registry Study is a phase II basket trial evaluating the antitumor activity of commercially available targeted agents in patients with advanced cancer and genomic alterations known to be drug targets. Results from cohorts of patients with metastatic breast cancer (BC) with FGFR1 and FGFR2 alterations treated with sunitinib are reported. METHODS: Eligible patients had measurable disease, Eastern Cooperative Oncology Group performance status 0-2, adequate organ function, and no standard treatment options. Simon's two-stage design was used with a primary end point of disease control (DC), defined as objective response (OR) or stable disease of at least 16 weeks duration (SD16+) according to RECIST v1.1. Secondary end points included OR, progression-free survival, overall survival, duration of response, duration of stable disease, and safety. RESULTS: Forty patients with BC with FGFR1 (N = 30; amplification only n = 26, mutation only n = 1, both n = 3) or FGFR2 (N = 10; amplification only n = 2, mutation only n = 6, both n = 2) alterations were enrolled. Three patients in the FGFR1 cohort were not evaluable for efficacy; all patients in the FGFR2 cohort were evaluable. For the FGFR1 cohort, two patients with partial response and four with SD16+ were observed for DC and OR rates of 27% (90% CI, 13 to 100) and 7% (95% CI, 1 to 24), respectively. The null hypothesis of 15% DC rate was not rejected (P = .169). No patients achieved DC in the FGFR2 cohort (P = 1.00). Thirteen of the 40 total patients across both cohorts had at least one grade 3-4 adverse event or serious adverse event at least possibly related to sunitinib. CONCLUSION: Sunitinib did not meet prespecified criteria to declare a signal of antitumor activity in patients with BC with either FGFR1 or FGFR2 alterations. Other treatments and clinical trials should be considered for these patient populations.

PRESTO: A Phase III, Open-Label Study of Intensification of Androgen Blockade in Patients With High-Risk Biochemically Relapsed Castration-Sensitive Prostate Cancer (AFT-19).

PURPOSE: Patients with biochemically recurrent prostate cancer (BRPC) after radical prostatectomy and a short PSA doubling time are at risk for distant metastases. Apalutamide, an androgen receptor antagonist, and abiraterone acetate plus prednisone (AAP) prolong survival in the metastatic setting. We evaluated whether intensification of androgen-deprivation therapy (ADT) improves outcomes in BRPC. PATIENTS AND METHODS: PRESTO is a randomized phase III, open-label trial in patients with BRPC and PSA doubling time ≤9 months (ClinicalTrials.gov identifier: NCT03009981). Patients were randomly assigned 1:1:1 to receive a finite 52-week treatment course with ADT control, ADT + apalutamide, or ADT + apalutamide + AAP. The primary end point was PSA progression-free survival (PSA-PFS), defined as serum PSA >0.2 ng/mL after treatment completion. RESULTS: Five hundred three patients were enrolled. The median PSA was 1.8 ng/mL (IQR, 1.0-3.6). At the first planned interim analysis, both experimental arms significantly prolonged PSA-PFS compared with the control arm (median, 24.9 months for ADT + apalutamide v 20.3 months for ADT; hazard ratio [HR], 0.52 [95% CI, 0.35 to 0.77]; P = .00047; median, 26.0 months for ADT + apalutamide + AAP v 20.0 months for ADT; HR, 0.48 [95% CI, 0.32 to 0.71]; P = .00008). Median time to testosterone recovery did not differ across treatment arms. The most common grade ≥3 adverse event was hypertension (7.5%, 7.4%, and 18% in ADT, ADT + apalutamide, and ADT + apalutamide + AAP arms, respectively). CONCLUSION: Intensified AR blockade for a finite duration prolongs PSA-PFS with a manageable safety profile, without adversely affecting time to testosterone recovery. The addition of apalutamide to ADT should be considered in patients with high-risk BRPC.

Radiographic Progression-Free Survival and Clinical Progression-Free Survival as Potential Surrogates for Overall Survival in Men With Metastatic Hormone-Sensitive Prostate Cancer.

PURPOSE: Despite major increases in the longevity of men with metastatic hormone-sensitive prostate cancer (mHSPC), most men still die of prostate cancer. Phase III trials assessing new therapies in mHSPC with overall survival (OS) as the primary end point will take approximately a decade to complete. We investigated whether radiographic progression-free survival (rPFS) and clinical PFS (cPFS) are valid surrogates for OS in men with mHSPC and could potentially be used to expedite future phase III clinical trials. METHODS: We obtained individual patient data (IPD) from 9 eligible randomized trials comparing treatment regimens (different androgen deprivation therapy [ADT] strategies or ADT plus docetaxel in the control or research arms) in mHSPC. rPFS was defined as the time from random assignment to radiographic progression or death from any cause whichever occurred first; cPFS was defined as the time from random assignment to the date of radiographic progression, symptoms, initiation of new treatment, or death, whichever occurred first. We implemented a two-stage meta-analytic validation model where conditions of patient-level and trial-level surrogacy had to be met. We then computed the surrogate threshold effect (STE). RESULTS: IPD from 6,390 patients randomly assigned from 1994 to 2012 from 13 units were pooled for a stratified analysis. The median OS, rPFS, and cPFS were 4.3 (95% CI, 4.2 to 4.5), 2.4 (95% CI, 2.3 to 2.5), and 2.3 years (95% CI, 2.2 to 2.4), respectively. The STEs were 0.80 and 0.81 for rPFS and cPFS end points, respectively. CONCLUSION: Both rPFS and cPFS appear to be promising surrogate end points for OS. The STE of 0.80 or higher makes it viable for either rPFS or cPFS to be used as the primary end point that is surrogate for OS in phase III mHSPC trials with testosterone suppression alone as the backbone therapy and would expedite trial conduct.

The Impact of Circulating Tumor Cell HOXB13 RNA Detection in Men with Metastatic Castration-Resistant Prostate Cancer (mCRPC) Treated with Abiraterone or Enzalutamide.

PURPOSE: HOXB13 is an androgen receptor (AR) coregulator specifically expressed in cells of prostatic lineage. We sought to associate circulating tumor cell (CTC) HOXB13 expression with outcomes in men with mCRPC treated with abiraterone or enzalutamide. EXPERIMENTAL DESIGN: We conducted a retrospective analysis of the multicenter prospective PROPHECY trial of mCRPC men (NCT02269982, n = 118) treated with abiraterone/enzalutamide. CTC detection and HOXB13 complementary DNA (cDNA) expression was measured using a modified Adnatest, grouping patients into 3 categories: CTC 0 (undetectable); CTC+ HOXB13 CTC low (<4 copies); or CTC+ HOXB13 CTC high. The HOXB13 threshold was determined by maximally selected rank statistics for prognostic associations with overall survival (OS) and progression-free survival (PFS). RESULTS: We included 102 men with sufficient CTC HOXB13 cDNA, identifying 25%, 31%, and 44% of patients who were CTC 0, CTC+ HOXB13 low, and CTC+ HOXB13 high, respectively. Median OS were 25.7, 27.8, and 12.1 months whereas the median PFS were 9.0, 7.7, and 3.8 months, respectively. In subgroup analysis among men with CellSearch CTCs ≥5 copies/mL and adjusting for prior abi/enza treatment and Halabi clinical risk score, the multivariate HR for HOXB13 CTC detection was 2.39 (95% CI, 1.06-5.40) for OS and 2.78 (95% CI, 1.38-5.59) for PFS, respectively. Low HOXB13 CTC detection was associated with lower CTC PSA, PSMA, AR-FL, and AR-V7 detection, and more liver/lung metastases (41% vs. 25%). CONCLUSIONS: Higher CTC HOXB13 expression is associated with AR-dependent biomarkers in CTCs and is adversely prognostic in the context of potent AR inhibition in men with mCRPC.

Molecular features of prostate cancer after neoadjuvant therapy in the phase 3 CALGB 90203 trial.

BACKGROUND: The phase 3 CALGB 90203 (Alliance) trial evaluated neoadjuvant chemohormonal therapy for high-risk localized prostate cancer before radical prostatectomy. We dissected the molecular features of post-treated tumors with long-term clinical outcomes to explore mechanisms of response and resistance to chemohormonal therapy. METHODS: We evaluated 471 radical prostatectomy tumors, including 294 samples from 166 patients treated with 6 cycles of docetaxel plus androgen deprivation therapy before radical prostatectomy and 177 samples from 97 patients in the control arm (radical prostatectomy alone). Targeted DNA sequencing and RNA expression of tumor foci and adjacent noncancer regions were analyzed in conjunction with pathologic changes and clinical outcomes. RESULTS: Tumor fraction estimated from DNA sequencing was significantly lower in post-treated tumor tissues after chemohormonal therapy compared with controls. Higher tumor fraction after chemohormonal therapy was associated with aggressive pathologic features and poor outcomes, including prostate-specific antigen-progression-free survival. SPOP alterations were infrequently detected after chemohormonal therapy, while TP53 alterations were enriched and associated with shorter overall survival. Residual tumor fraction after chemohormonal therapy was linked to higher expression of androgen receptor-regulated genes, cell cycle genes, and neuroendocrine genes, suggesting persistent populations of active prostate cancer cells. Supervised clustering of post-treated high-tumor-fraction tissues identified a group of patients with elevated cell cycle-related gene expression and poor clinical outcomes. CONCLUSIONS: Distinct recurrent prostate cancer genomic and transcriptomic features are observed after exposure to docetaxel and androgen deprivation therapy. Tumor fraction assessed by DNA sequencing quantifies pathologic response and could be a useful trial endpoint or prognostic biomarker. TP53 alterations and high cell cycle transcriptomic activity are linked to aggressive residual disease, despite potent chemohormonal therapy.

Cobimetinib Plus Vemurafenib in Patients With Solid Tumors With BRAF Mutations: Results From the Targeted Agent and Profiling Utilization Registry Study.

PURPOSE: The Targeted Agent and Profiling Utilization Registry Study is a phase II basket study evaluating antitumor activity of commercially available targeted agents in patients with advanced cancers with genomic alterations known to be drug targets. The results in a cohort of patients with solid tumors with BRAF mutations treated with cobimetinib plus vemurafenib are reported. METHODS: Eligible patients had measurable disease (RECIST v.1.1), Eastern Cooperative Oncology Group performance status 0-2, adequate organ function, and no standard treatment options. The primary end point was disease control (DC), defined as complete response (CR) or partial response (PR) or stable disease of at least 16-weeks duration (SD16+). Low-accruing histology-specific cohorts with BRAF mutations treated with cobimetinib plus vemurafenib were collapsed into a single histology-pooled cohort for this analysis. The results were evaluated on the basis of a one-sided exact binomial test with a null DC rate of 15% versus 35% (power, .82; α, .10). The secondary end points were objective response (OR), progression-free survival, overall survival, duration of response, duration of stable disease, and safety. RESULTS: Thirty-one patients with solid tumors with BRAF mutations were enrolled. Twenty-eight patients were evaluable for efficacy. Patients had tumors with BRAF V600E (n = 26), K601E (n = 2), or other (n = 3) mutations. Two patients with CR (breast and ovarian cancers; V600E), 14 with PR (13 V600E, one N581I), and three with SD16+ (two V600E, one T599_V600insT) were observed with a DC rate of 68% (P < .0001; one-sided 90% CI, 54 to 100) and an OR rate of 57% (95% CI, 37 to 76). Nineteen patients experienced ≥one drug-related grade 3-5 adverse event or serious adverse event including one death attributed to treatment-related kidney injury. CONCLUSION: Cobimetinib plus vemurafenib showed antitumor activity in patients with advanced solid tumors with BRAF V600E mutations; additional study is warranted to confirm the antitumor activity in tumors with non-V600E BRAF mutations.