Immunohistochemical (IHC) subtypes of metastatic bladder cancer (mBC) using GATA3 and CK5/6

557

Background: Genomic analyses have identified that bladder cancers can be divided into distinct molecular subtypes: luminal and basal. IHC markers GATA3 and CK5/6 have demonstrated >80% accuracy in assessing the luminal and basal subtypes of primary bladder tumors and may be easily utilized in clinical practice. Correlation of the primary bladder subtype with that of metastatic sites has not been demonstrated and associations with clinical outcomes are uncertain. Methods: We retrospectively identified patients with mBC who were treated with systemic therapy and had biopsies of either primary bladder or metastatic sites. Patient demographic, metastatic sites, treatment patterns, and clinical outcomes were recorded. Tissue microarrays (TMA) were constructed from primary and/or metastatic tumors. IHC was performed using mouse monoclonal antibodies: GATA-3 (L50-823, Pharmingen, 1:200) and cytokeratin 5/6 (XM26, Thermo Fisher, 1:100). Luminal (GATA3+, CK5/6-), basal (GATA3-, CK5/6+), double positive (GATA3+, CK5/6+) or double negative (GATA3-, CK5/6-) subtyping was applied. Concordance of matched bladder and metastatic pairs was quantified using Cohen’s kappa. Wilcoxon rank-sum tests were used for comparison of continuous and ordinal measures and chi-square tests were performed for comparison of categorical measures. Survival was estimated by Kaplan-Meier method; multivariable Cox analysis was performed. Results: Of 62 specimens, 37 bladder and 16 metastatic sites were interpretable. Four IHC subtype patterns were identified, most were luminal (n=20) followed by double-positive (n=12), basal (n=5), and double-negative (n=5). Of 10 pairs of matched primary tumor and metastatic sites, there was near-perfect subtype concordance between primary and metastatic tumors (κ=0.84; 95% CI:0.58-1.00). No association between sites of metastatic progression and subtype were identified, nor was there any difference in overall survival between the subtypes (p = 0.70). The basal subtype had numerically worse survival compared to the luminal subtype, HR =0.164 (95% CI: 0.02-1.58, p=0.12). Conclusions: IHC subtyping by GATA3 and CK5/6 is feasible in the clinical setting and showed strong correlation between primary and metastatic sites. A larger analysis is planned to further investigate associations with clinical features and outcomes. [Table: see text]

Impact of pre-existing anemia and/or packed red blood cell transfusion prior to Radium-223 administration on oncologic outcomes

67

Background: Radium-223 (Ra-223), a targeted alpha-emitting radiopharmaceutical approved for the treatment of metastatic prostate cancer (mPC), can cause myelosuppression. In the ALSYMPCA trial 30% of patients developed cytopenias, including 13% with grade 3/4 anemia. Therefore, it is recommended that only men with a hemoglobin ≥10 g/dL, platelet count ≥100,000/mm3, and ANC ≥1,500/mm3 be considered for Ra-223. Since the FDA approval of Ra-223 in 2013, several new treatments have been approved for men with mPC. With the changing therapeutic landscape, we anticipate more patients (pts) will have preexisting cytopenia prior to Ra-223 consideration. Hence, clinicians are increasingly likely to face the dilemma of whether it is safe and efficacious to administer Ra-223 in the setting of Hgb ≤10 with/without RBC transfusion support. Methods: We retrospectively identified pts with mPC treated with Ra-223, including a subset of men with Hgb <10g/dl at the Medical College of Wisconsin and Tulane Cancer Center from 2014 – 2019. Clinical data including demographics, prior cancer treatments, laboratory data, blood product transfusion data, and oncologic outcomes were collected. Survival was estimated using Kaplan-Meier method and statistical analysis was conducted using student’s t-test. Results: Sixty-two pts were identified. Median age at the time of Ra-223 was 75.3 years. Of these, nearly 20% (n=12) had a Hgb <10 g/dL and/or received RBC transfusions to meet “eligibility criteria” prior to beginning Ra-223 treatments. Compared to men who had Hgb >10g/dL, men with Hgb <10g/dL required more RBC transfusions both during and after Ra-223 treatment and had significantly worse oncologic outcomes. No patients experienced treatment delays of more than 1 week. There were no significant differences in the median number of treatments prior to Ra-223, median number of Ra-223 treatments received, platelet count nadir, or ANC nadir. Conclusions: Pre-existing Hgb < 10 g/dl and/or RBC transfusions prior to Ra-223 therapy is associated with worse oncologic outcomes in mPC, suggesting that the benefit of Ra-223 is limited in this subset. A larger sample size is needed to further validate our findings. Multivariable analysis is planned. [Table: see text]

A phase 2 study of cabozantinib in combination with atezolizumab as neoadjuvant treatment for muscle-invasive bladder cancer (HCRN GU18-343) ABATE study

TPS4618

Background: ABACUS and PURE-01 trials demonstrated the activity of single agent atezolizumab and pembrolizumab respectively as neoadjuvant therapy for muscle invasive bladder carcinoma (MIBC). However, downstaging to non-muscle invasive disease was noted in only 50 percent of patients. Resistance to programmed death (PD)- 1/L1 antibodies is likely to include factors such as impaired dendritic cell maturation/function, infiltration of T-Regs and myeloid derived suppressor cells, impaired T-cell priming and T-cell trafficking in tumors. Cabozantinib is a tyrosine kinase inhibitor which targets MET, AXL, MER, Tyro3 and VEGFR2. Cabozantinib has a unique immunomodulatory profile and has demonstrated clinical activity as monotherapy and in combination with PD-1/L1 antibodies in various solid tumors including urothelial cancer (UC), renal cell, castrate- resistant prostate and non-small cell lung cancer. We hypothesize that the combination of cabozantinib and atezolizumab as neoadjuvant therapy for MIBC would improve rates of pathologic downstaging compared to single-agent checkpoint inhibitors. Methods: ABATE is an open-label, single arm, multi-center study to assess the efficacy and safety of cabozantinib with atezolizumab as neoadjuvant therapy for cT2-T4aN0/xM0 MIBC. An estimated 42 patients will be enrolled to obtain 38 evaluable patients, and the study will have over 80% power to declare the investigational combination to be successful using a Bayesian evaluation at 90% posterior probability cutoff, if the response probability is 59%, i.e., 20% higher than the 39% response rate with the single agent atezolizumab. Eligible patients will receive cabozantinib 40 mg PO daily with atezolizumab 1200mg every 3 weeks for a total duration of 9 weeks (3 cycles) followed by radical cystectomy. Adults (≥18 years) with resectable MIBC who are either cisplatin-ineligible or decline cisplatin-based chemotherapy are eligible. Patients are required to have an ECOG PS of 0-2 and provide tumor tissue for PD-L1 expression analysis. UC should be predominant component (≥ 50%). Previous systemic anticancer therapies for MIBC are not permitted. CT/MRI will be performed before investigational therapy and cystectomy. Primary endpoint is pathologic response rate defined as the absence of residual muscle-invasive cancer in the surgical specimen (< pT2). Secondary endpoints are safety and toxicity, pathologic complete response rate and event-free survival. Exploratory end points include patient-reported outcomes and outcome associations with biomarkers. Accrual began May 2020. Clinical trial information: NCT04289779.

A single-arm, open-label, phase 2 study evaluating pacritinib for patients with biochemical recurrence after definitive treatment for prostate cancer: Blast study

TPS220

Background: Androgen deprivation therapy (ADT) achieved with gonadotropin releasing hormone (GnRH) agonist or antagonist is considered the standard of care for men with prostate cancer (PC) who develop biochemical recurrence (BCR) after definitive treatment. ADT is associated with significant adverse effects in this asymptomatic population, and hence there is an unmet need for alternate non-hormonal options. Androgen receptor (AR) and its variants (AR-V) are persistently expressed in the majority of the cells in recurrent PCs and drives PC growth. Jak2-Stat5 signaling has been shown to sustain PC cell viability and is critical for PC tumor growth. Stat5 activation in PC at the time of surgery predicts early PC recurrence. Our investigation of the molecular targets downstream of Jak2-Stat5 signaling have revealed the AR gene as a critical target, and the Jak2-Stat5 pathway represents a target to inhibit expression of diverse AR and AR-V species and thereby control of PC growth. Pacritinib (PAC) is a novel JAK2 inhibitor that suppresses wild-type Jak2 in cell-based assays and has demonstrated promising antitumor activity in myelofibrosis. We hypothesize that PAC inhibition of Jak2-Stat5 signaling will induce biochemical responses in men with recurrent PC by depleting AR and AR-V. Methods: BLAST (NCT04635059) is a single arm, open-label, phase 2 study of PAC (200mg BID) for patients with PC who underwent definitive treatment and developed BCR. Eligibility criteria include histologically confirmed PC, BCR with a PSA doubling time ≤ 9 months, PSA > 0.5 ng/mL, and serum testosterone > 150 ng/dL. 46 subjects will be enrolled with a primary objective to assess the effect of PAC on time to PSA progression. The primary endpoint is six-month PSA progression free survival per PCWG3 criteria. The null hypothesis that the median PSA-progression-free survival is six months will be tested against a one-sided alternative for the six-month PSA-progression-free survival probability exceeding 50%. Secondary endpoints include time to subsequent therapy, safety and toxicity. Exploratory endpoints include effect of PAC on geriatric domains. An interim analysis will be performed when 10 patients have been treated and followed for six months. Accrual began in July 2021. Clinical trial information: NCT04635059.

A phase 2 study of cabozantinib in combination with atezolizumab as neoadjuvant treatment for muscle-invasive bladder cancer (HCRN GU18-343) ABATE study

TPS4591

Background: ABACUS and PURE-01 trials demonstrated the activity of single agent atezolizumab and pembrolizumab respectively as neoadjuvant therapy for muscle invasive urothelial carcinoma (MIUC). However, downstaging to non-muscle invasive disease was noted in only 50 percent of patients. Resistance to programmed death (PD)- 1/L-1 antibodies is likely to include factors such as impaired dendritic cell maturation/function, infiltration of T-Regs and myeloid derived suppressor cells, impaired T-cell priming and T-cell trafficking in tumors. Cabozantinib is a tyrosine kinase inhibitor which targets MET, AXL, MER, Tyro3 and VEGFR2. Cabozantinib has a unique immunomodulatory profile and has demonstrated clinical activity as monotherapy and in combination with PD-1/L1 antibodies in various solid tumors including UC, renal cell cancer, castrate- resistant prostate cancer, and non-small cell lung cancer. We hypothesize that the combination of cabozantinib and atezolizumab as neoadjuvant therapy for MIUC would improve rates of pathologic downstaging compared to single-agent checkpoint inhibitors. Methods: ABATE(NCT04289779) is an open-label, single arm, multi-center study to assess the efficacy and safety of cabozantinib with atezolizumab as neoadjuvant therapy for cT2-T4aN0/xM0 MIUC. An estimated 38 patients will be enrolled and receive cabozantinib 40 mg PO daily with atezolizumab 1200mg every 3 weeks for a total duration of 9 weeks followed by radical cystectomy. Adults (≥18 years) with resectable UC who are either cisplatin-ineligible or decline cisplatin are eligible. Patients are required to have an ECOG PS of 0-2 and provide tumor tissue for PD-L1 analysis. UC should be predominant component (≥ 50%). Previous systemic anticancer therapies for MIUC are not permitted. CT/MRI will be performed before investigational therapy and cystectomy. Primary endpoint is pathologic response rate defined as the absence of residual muscle-invasive cancer in the surgical specimen ( < pT2). Secondary endpoints are safety and toxicity, pathologic complete response rate and event-free survival. Exploratory end points include patient-reported outcomes and outcome associations with biomarkers. Accrual began May 2020. Clinical trial information: NCT04289779.

Long-Term Outcomes of Dose-Escalated Pelvic Lymph Node Intensity-Modulated Radiation Therapy (IMRT) With a Simultaneous Hypofractionated Boost to the Prostate for Very High-Risk Adenocarcinoma of the Prostate: A Prospective Phase II Clinical Trial

PURPOSE

There remains limited data as to the feasibility, safety, and efficacy of higher doses of elective radiation therapy to the pelvic lymph nodes in men with high-risk prostate cancer. We conducted a phase II study to evaluate moderate dose escalation to the pelvic lymph nodes using a simultaneous integrated boost to the prostate.

METHODS AND MATERIALS

Patients were eligible with biopsy-proven adenocarcinoma of the prostate, a calculated lymph node risk of at least 25%, Karnofsky performance scale ≥70, and no evidence of M1 disease. Acute and late toxicity were prospectively collected at each follow-up using Common Terminology Criteria for Adverse Events version 4.0 (CTCAE v4.0). The pelvic lymph nodes were treated to a dose of 56 Gy over 28 fractions with a simultaneous integrated boost to the prostate to a total dose of 70 Gy over 28 fractions using intensity-modulated radiation therapy.

RESULTS

Thirty patients were prospectively enrolled from October 2010 to August 2014. Median patient age was 70 years (57-83), pretreatment prostate-specific antigen was 11.5 ng/mL (3.23-111.5), T stage was T2c (T1c-T3b), and Gleason score was 9 (6-9). CTCAE v4.0 rate of any grade 1 or 2 genitourinary and gastrointestinal toxicity were 55% and 44%, respectively, and there was 1 reported acute grade 3 genitourinary and gastrointestinal toxicity, both unrelated to protocol therapy. With a median follow-up of 6.4 years, the biochemical failure free survival rate was 80.2%, and mean biochemical progression free survival was 8.3 years (95% confidence interval [CI], 7.2-9.4). The prostate cancer specific survival was 95.2%, and mean prostate cancer specific survival was 8.7 years (95% CI, 8.0-9.4). Five-year distant metastases free survival was 96%. Medians were not reached.

CONCLUSIONS

In this single arm, small, prospective feasibility study, nodal radiation therapy dose escalation was safe, feasible, and seemingly well tolerated. Rates of progression free survival are highly encouraging in this population of predominately National Comprehensive Cancer Network very high-risk patients.

Emerging clinical phenotype of bone metastatic urothelial cancer (mUC): Association of early osseous metastases (EOM) and outcomes

e17007

Background: Outcomes of patients (pts) with mUC with EOM have not thoroughly been described in the age of immuno-oncology. We hypothesized that EOM is associated with worse outcomes when compared to pts with non-osseous metastases (NOM). Methods: We used a multi-institutional database of pts with mUC who received systemic treatment (trt) between March 2005 and August 2019, to assess survival and palliative outcomes of pts with EOM vs NOM at the time of metastatic diagnosis (met dx). Wilcoxon rank-sum and chi-square tests were performed. Survival was estimated by Kaplan-Meier method, Cox regression analysis was performed. Results: We identified 270 pts, 72% men, mean age 67 ± 11 years, 28% never smokers. At met dx, 27% (n = 72) had ≥ 1 EOM; these pts were more likely to have de novo metastases vs. those with recurrent metastases (42% vs 19%, p < 0.001). Pts with EOM were more likely to have a change or stop in 1st line trt due to clinical progression (30.6% vs 15.7%, p = 0.006), and received fewer total lines of systemic trt, median of 1.0 (1.0-5.0) vs. 2.0 (1.0-8.0), p = 0.05. Pts with EOM had shorter median overall survival (OS) vs. those with NOM, (6.1 vs 13.7 months, p < .0001), HR = 2.79 (95% CI:1.95-3.97, p < .0001). Median OS was shorter for pts with EOM who received 1st line immune checkpoint inhibitor (n = 14) vs platinum-based chemotherapy (n = 43), (1.6 vs 9.1 months, p = 0.003). Pts with EOM received higher opioid analgesic doses at the first and last oncology outpatient visits compared to pts with NOM with mean morphine milligram equivalent (MME) dose of 60 ± 91 vs 28 ± 65 at first visit, p = 0.004, and 171 ± 214 vs. 94 ± 229 at last visit, p < 0.001. Conclusions: The presence of EOM in mUC is associated with worse outcomes vs. pts with NOM. Pts with EOM may benefit from 1st line platinum-based chemotherapy vs. checkpoint immunotherapy. Furthermore, pts with EOM experience more pain than pts with NOM and may benefit from early engagement with palliative care. Pts with EOM represent a population with a highly unmet need for systemic, targeted and/or radiation interventions. Molecular subtypes may further define these pts and analysis is planned. We encourage ongoing clinical trials to report outcomes in pts with EOM. A consensus on reporting of non-measurable disease is also needed. [Table: see text]

A phase II study of enzalutamide (Enz) with dutasteride (Dut) or finasteride (Fin) in men ≥ 65 years with hormone-naive systemic prostate cancer (HNSPCa): Tolerability and geriatric asssessment (GA) results

e16518

Background: Older men are at a high risk for adverse events (AEs) from androgen deprivation therapy (ADT). In this phase II study, we evaluated Enz and Dut/Fin in lieu of ADT for at-risk older patients with HNSPCa. Methods: Eligible patients were ≥65 years (y); at high risk of AEs from ADT by GA or treating physicians; metastatic (M1) or non-metastatic (M0) HNSPCa with a PSA doubling time ≤ 9 months and testosterone > 50ng/dl. They received Enz 160 mg/day and Dut 0.5 mg/day or Fin 5 mg/day until disease progression. GA was performed at baseline and week (wk) 61 and/or at the time of progression. GA included validated tests: Instrumental Activities of Daily Living (IADL), fall history, Short Physical Performance Battery (SPPB), Geriatric Depression Scale (GDS), and Montreal Cognitive Assessment (MOCA). The prevalence of impairment for each assessment was calculated; change in prevalence from baseline to wk 61 was analyzed using paired sample t-test. Results: 43 patients were enrolled in the study. Median age at enrollment was 78 y (range 66-94) and 93% were ECOG 0-1; 37% (n = 16) had M0 and 63% (n = 27) had M1 HNSPCa, with the majority (67%) having Gleason 6 or 7 disease. At baseline, 18.6% met the cutoff for impairment for IADLs, 53.7% for SPPB, 7.9% for GDS and 64.3% for MOCA; 9.8% had a recent fall. Median baseline PSA was 11.38 ng/ml (range: 2-145). At the time of analysis, 29 men (67.4%) remain on study treatment. 95.3%, 74.4% and 46.5% of patients reported at least one Grade 1, 2 or 3 AE respectively. No patient had a Grade 4 AE and one Grade 5 AE was reported but was an unrelated event. The most common Grade 3 AEs were hypertension (27.8%), GI (19.4%), and cardiac (8.3%); all Grade 3 GI AEs reported were deemed unrelated to the study drugs. Only impairment in ≥ 1 IADL showed a statistically significant increase in prevalence at wk 61 of treatment (40.6%) compared to baseline (18.6%, p = 0.036). Conclusions: For older men with HNSPCa, Enz with Dut/Fin demonstrated efficacy with reasonable toxicity profile, and no significant impact on the majority of GA domains. Clinical trial information: NCT02213107.

Effect of β-hydroxy-β-methylbutyrate (HMB) on muscle strength in older men with prostate cancer (Pca) started on androgen deprivation therapy (ADT): Preliminary results of an open-label, randomized trial

258

Background: ADT causes muscle weakness and wasting within 3 months (mo), causing older men on ADT to experience functional impairments and falls. HMB, a leucine metabolite which decreases muscle protein breakdown, improves strength, fat-free mass and function in older patients when given with arginine (A) and glutamine (G). Use of HMB +AG in older men with PCa starting on ADT to improve muscle loss and function has not been reported. Methods: Men age ≥ 60 with Pca starting on ADT were eligible. 42 men to date have been randomized to receive HMB + AG (Juven) twice daily for 3 mo vs no supplement. Physical performance measures using the Short Physical Performance Battery (SPPB) and hand dynamometer measurements were done at baseline and 3 mo. Both of these validated tests predict morbidity and mortality in older patients. Information on primary outcome, body composition, will be reported in the future according to study plan. Interim results are reported here to describe functional geriatric outcomes. Results: 42 men (mean age 70.2) with Pca (42.4% localized, 27.3% biochemical recurrence, 30.3% metastatic) have enrolled to date. Change in SPPB score favored HMB group: 12.6% of HMB vs 23.1% of controls had decline of ≥ 1point (pt) and 56.3% of HMB vs 15.4% of controls had increase of ≥ 1 pt (p = 0.045). The change in timed chair stand portion of SPPB (measures quadriceps strength) trended in favor of HMB group: -1.5 ± 2.9 seconds (sec) for HMB vs +0.4 ± 2.5 sec for controls, p = 0.073. 41.2% of HMB vs 15.4% of controls experienced an improvement in chair stand score. Change in hand grip strength also favored HMB group: 52.9% of HMB vs 84.6% of controls lost strength and 29.4% of HMB vs 0 controls gained strength, p = 0.047. No significant side effects were reported in HMB group. Conclusions: These are preliminary results of an ongoing trial. HMB is well tolerated in men with PCa on ADT. There is a trend in all measures of muscle function in favor of the HMB group. A much higher than expected % of men on HMB experienced improvement in measures of muscle function despite being on ADT. Further studies are ongoing to clarify the role of HMB in older men on ADT. Clinical trial information: NCT01607879.

Liver-directed therapy (LDT) for metastatic renal cell carcinoma (mRCC): Single center experience

681

Background: Liver metastases arising from RCC are common and signify a poor prognosis. Given the negative impact of liver metastases on overall survival (OS) and quality of life, it is reasonable to to consider therapies directly targeting these lesions in select patients. Little is known about how minimally invasive LDT affects outcomes in patients with mRCC. Methods: Nine patients with mRCC underwent LDT for liver-dominant or liver-only metastatic disease between 2005 and 2015. Retrospective chart review was performed under an IRB protocol to identify patient and disease characteristics, imaging response, and time to next systemic treatment, OS and toxicities. Patients were seen in clinic at one month post-LDT to monitor for toxicities. Imaging was obtained within 2 months prior to treatment and at 3 and 6 months following LDT. Results: Each patient underwent a median of 2.3 procedures. A total of 18 transarterial chemoembolizations (TACE) and 5 yttrium-90 radioembolizations were performed. 2 patients had metastatic disease confined to the liver, and 7 had liver-dominant disease. 7 had multifocal disease involving < 25% of the liver, and 2 had multifocal disease involving > 25% of the liver. 8/9 patients received prior systemic therapies, receiving a median of 3 (0-4) distinct treatments. 4/9 patients were undergoing systemic therapy at the time of LDT, 1 patient declined further treatment, and the median time to initiation of the next systemic therapy in the remaining patients was 3 months (range 2-4 months). Median OS from first line systemic therapy was 39 months, 95% CI [25.9-53.3], and the median OS from the first LDT was 22 months (from 5-45 months). Follow-up imaging post-LDT showed PR or SD in 88% of cases at 3 months and 44% of cases at 6 months. At one month post-procedure, 8/9 patients maintained performance status, and only one patient experienced CTCAE grade 3-4 toxicity. Conclusions: The median OS in RCC patients with liver disease and systemic therapy alone is 14.3 months. The improved median OS of 39 months with LDT in our unmatched and heavily pretreated cohort suggests a role for LDT. LDT is generally well tolerated and should be considered for patients with liver-dominant mRCC with good performance status.

A phase II study of enzalutamide (Enz) with dutasteride (Dut) or finasteride (Fin) in men ≥ 65 years with hormone-naive systemic prostate cancer (HNSPCa)

179

Background: Older men are at a high risk for adverse events (AEs) from androgen deprivation therapy (ADT). In prior studies, peripheral androgen blockade with bicalutamide and Fin was better tolerated but less efficacious than ADT in HNSPCa. The potential syngerism of Enz (a potent antiandrogen) and Dut/Fin (5-a reductase inhibitors for conversion of testosterone [T] to dihydrotestosterone [DHT]) provided the rationale for this Phase II study that examined the clinical efficacy and safety of Enz with Dut/Fin in men > 65 years with HNSPCa. Methods: Eligible patients were > 65 years (y) ; at a high risk of AE from ADT by comprehensive geriatric assessment or treating physicians; had metastatic (M1) or biochemical recurrent (M0) HNSPCa with a PSA doubling time < 9 months; and had T > 50ng/dl. They received Enz (160mg daily) and Dut (0.5mg daily) or Fin (5mg daily) until disease progression according to the Prostate Cancer Working Group 2 guidelines. The primary study endpoint is time to PSA progression. The secondary endpoints are time to PSA nadir and treatment-related AEs. Results: As of July 31, 2016, 24 patients were screened (3 ineligible) and 21 were enrolled with a median follow-up of 31 weeks (7-79). Median age at enrollment was 79.5 y (66-94) and 14 %, 72% and 14% had ECOG performance status of 0, 1, and 2, respectively. 57% (n = 12) had M0 and 43% (n = 9) had M1 HNSPCa, with 18%, 62%, 5%, and 10% having Gleason 6, 7, 8, and 9 disease, respectively (5% with unkown Gleason sum). The median PSA at enrollment was 12 ng/ml (2-102). The median time to 90% PSA decline after treatment initiation was 7 weeks (7-20) and 92% achieved 80% DHT decline in 9 months. At the time of analysis, all patients had ongoing PSA decline of > 90% without radiographic evidence of disease progression. Common Grade 1 AEs included gynecomastia (28%), fatigue (28%), hot flashes (19%) and paresthesias (15%). One patient withdrew from the study due to Grade 2 paresthesia. None had Grade 3 or 4 treatment-related AEs. One patient died due to colitis unrelated to study treatments. Conclusions: Enz with Dut/Fin appears to have clinical activity for older patients with M0 and M1 HNSPCa with acceptable side effects. Clinical trial information: NCT02213107.

Predictors of response to platinum (Pt)-based chemotherapy in metastatic castration-resistant prostate cancer (mCRPC)

e575

Background: Aggressive variant PC (AVPC) is a well-described subtype of PC which portends a poor prognosis. Studies have shown an increase in progression-free survival(PFS) when Pt is added to taxane-based treatment in AVPC. Clinical features including visceral metastasis, lytic bone lesions, low PSA, short responses to androgen suppression and high Gleason score at diagnosis predict response to upfront docetaxel (D) and Pt (Aparicio et. al. Clin Cancer Res 2013). Our objective was to study the effect of baseline characteristics on PFS with D+Pt in D-pretreated CRPC. Methods: A retrospective review of D-pretreated mCRPC men who received D (60-75 mg/m2) and carboplatin (C, AUC 4-5) at our institution between 2008- 2015 were included in this analysis. All patients had metastatic CRPC, were heavily pre- treated (median treatments = 4) and received at least one cycle of D+C. Numerical data was analyzed using Student’s T-test; binary data was analyzed with Z-proportions test. Results: 28 patients were identified. The median age was 60 yrs(48-73); median PSA at diagnosis was 21ng/dl(0.3-5000); median PSA at the start of D+C was 115.32 ng/dl( 0.65-1395). The response rate was 60.7% and the median time to response was 1 mo. The median reduction in PSA was 48.13%. The median PFS was 6 mo, and median OS was 10 mo. Common treatment – related side effects included grade 1 fatigue (82.14%), pancytopenia (42.86%), and febrile neutropenia (10.71%). Correlation of baseline characteristics to PFS was evaluated. Short response to ADT < 1 yr (p < 0.05), prior response to D (PFS > 6 months) ( p = 0.037), and presence of visceral mets (p < 0.05) predicted better response to D+C. Age (p = 0.27), Gleason score at diagnosis (p = 0.08), performance status at start of therapy (p = 0.27), PSA at diagnosis (p = 0.35), and PSA at start of D+C (p = 0.420) did not predict response. Conclusions: D+C is effective and safe in D pretreated CRPC. Response to prior D, short response to ADT, and the presence of visceral metastasis predicted response to D+C. These are features of AVPC. Prospective studies to validate our findings and identify molecular characteristics of Pt responders are needed in this heavily pre-treated “real world” patient population.

A phase I/II trial of BNC105P with everolimus in metastatic renal cell carcinoma (mRCC) patients: Updated phase I results of the Disruptor-1 trial

4563

Background: BNC105P is an inhibitor of tubulin polymerization. In vivo exposure to BNC105P leads to selective damage of tumor vasculature in both primary and metastatic lesions, causing disruption of blood flow to tumors, hypoxia and associated tumor necrosis. BNC105P also has a direct anti-proliferative action on cancer cells. Up regulation of the mTOR pathway has been identified as a cellular response to hypoxic stress. The combined use of BNC105P with an agent active against mTOR may improve clinical outcome in patients with progressive mRCC who are refractory to VEGFR-directed tyrosine kinase inhibitors (TKI). Methods: A phase I/II study in mRCC patients who have received 1-2 prior TKIs was undertaken. The phase I component enrolled 12 subjects at 4 dose levels of BNC105P (4.2, 8.4, 12.6, 16 mg/m2; IV infusion Days 1 & 8, 21-day repeating cycle). Everolimus was administered concurrently (10 mg p.o.). PK analysis was performed during Cycle 1. Biomarker samples (pre- and post-dose during Cycle 1) were analyzed for 70 plasma analytes including VEGF, PDGF and other markers associated with angiogenesis and vascular responses. Results: Updated results from the completed phase I component confirm the BNC105P / everolimus combination was well tolerated. No DLTs (drug-related, during cycle 1) were observed in any of the phase I subjects. Toxicities on study deemed to be drug-related (either single agent or combination) included single Grade 3 events of anemia and pericardial effusion. Grade 2 events of fatigue, anemia and oral mucositis were also observed. Eight of the 12 phase I subjects achieved disease stabilization. Across all subjects a median of 6 cycles (range: 1-24) was administered, with removal from study predominantly due to disease progression. PK analysis confirmed no drug-drug interaction. The randomized phase II component of the study continues and will compare everolimus given concomitantly with BNC105P to a sequential approach (everolimus followed by BNC105P). Conclusions: Full dose BNC105P (16 mg/m2) can be combined with full dose everolimus (10 mg) and is being further evaluated in a randomized phase II study. Clinical trial information: NCT01034631.

Updated phase I results of a phase I/II trial of BNC105P with everolimus in patients with metastatic renal cell carcinoma (mRCC)

397

Background: BNC105P is an inhibitor of tubulin polymerization. In vivo exposure to BNC105P leads to selective damage of tumor vasculature in both primary and metastatic lesions, causing disruption of blood flow to tumors, hypoxia and associated tumor necrosis. BNC105P also has a direct anti-proliferative action on cancer cells. Up regulation of the mTOR pathway has been identified as a cellular response to hypoxic stress. The combined use of BNC105P with an agent active against mTOR may improve clinical outcome in patients with progressive mRCC who are refractory to VEGFR-directed tyrosine kinase inhibitors (TKI). Methods: A phase I/II study in mRCC patients who have received 1-2 prior TKIs was undertaken. The phase I component enrolled 12 subjects at 4 dose levels of BNC105P (4.2, 8.4, 12.6, 16 mg/m2; IV infusion Days 1 and 8, 21-day repeating cycle). Everolimus was administered concurrently (10 mg p.o.). PK analysis was performed during cycle 1. Results: Updated results from the completed phase I component confirm the BNC105P/everolimus combination was well tolerated. No DLTs (drug-related, during cycle 1) were observed in any of the phase I subjects. Toxicities on study deemed to be drug-related (either single agent or combination) included single grade 3 events of anemia and pericardial effusion. Grade 2 events (more than 1 occurrence) of fatigue, anemia, and oral mucositis were also observed. 8 of the 12 phase I subjects achieved disease stabilization (7 of these subjects had a minimum time on therapy of 18 weeks, 6 cycles). Across all subjects a median of 6 cycles (range: 1-21) was administered, with removal from study predominantly due to disease progression. PK analysis confirmed no drug-drug interaction. The randomized phase II component of the study continues and will compare everolimus given concomitantly with BNC105P to a sequential approach (everolimus followed by BNC105P). Conclusions: BNC105P (16 mg/m2) can be combined with full dose everolimus and is being evaluated in a randomized phase II study. Clinical trial information: NCT01034631.

Phase I results of a phase I/II trial of BNC105P with everolimus in metastatic renal cell carcinoma (mRCC) patients previously treated with VEGFR tyrosine kinase inhibitors

4603

Background: BNC105P is an investigational agent that destabilizes tubulin polymers leading to selective damage of tumor vasculature, causing disruption of blood flow to tumors, hypoxia and associated tumor necrosis. BNC105P also has a direct anti-proliferative action on cancer cells. Preclinical investigations have demonstrated that BNC105P is effective at selectively damaging the vasculature in both primary and metastatic lesions. Up regulation of the mTOR pathway has been identified as a survival response by the tumor to hypoxic insult. It follows that the combined use of BNC105P with an agent active against mTOR may improve clinical outcome in patients with progressive mRCC who are refractory to VEGFR-directed tyrosine kinase inhibitors (TKI). Methods: A phase I/II study in mRCC patients who have received 1-2 prior TKIs was undertaken. Using a classic 3+3 design, the phase I component of this study enrolled 12 subjects at 4 dose levels of BNC105P (4.2, 8.4, 12.6, 16 mg/m2; IV infusion Days 1 and 8, 21-day repeating cycle). Everolimus was administered concurrently (10 mg p.o.). PK analysis was performed during Cycle 1. Results: The phase I component has been completed. The BNC105P / everolimus combination was well tolerated. No DLTs (drug-related, during cycle 1) were observed in any of the phase I subjects. Toxicities on study deemed to be drug-related (either single agent or combination) included single grade 3 events of anemia and pericardial effusion. Grade 2 events (more than 1 occurrence) of fatigue, anemia and oral mucositis were also observed. Seven phase I subjects achieved at least disease stabilization with a minimum time on therapy of 18 weeks (6 cycles). Across all subjects a median of 6 cycles (range: 1-15) was administered. PK analysis confirmed no drug-drug interaction. The randomized phase II component of the study continues and will compare everolimus given in combination with BNC105P to a sequential approach (everolimus followed by BNC105P). Conclusions: The MTD of BNC105P (16 mg/m2) can be combined with full dose everolimus and is being evaluated in the randomized phase II study.

Phase I/II study of a BNC105P/everolimus regimen for progressive metastatic renal cell carcinoma (mRCC) following prior tyrosine kinase inhibitors (Hoosier Oncology Group)

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Background: BNC105P is a Vascular Disruption Agent (VDA) that destabilizes tubulin polymers leading to selective damage of tumor vasculature, hypoxia and associated tumor necrosis. BNC105P also has a direct anti-proliferative action on cancer cells. Up regulation of the mTOR pathway has been identified as a survival response by the tumor to hypoxic insult. Preclinical investigations demonstrated that BNC105P is effective at selectively damaging the vasculature in primary and metastatic lesions. Furthermore, BNC105P monotherapy compared well with sunitinib in mice bearing kidney tumors. It follows that the combined use of this VDA with an agent active against mTOR may improve clinical outcome in patients with progressive mRCC who are refractory to tyrosine kinase inhibitors (TKI).

Methods: A phase I/II study in mRCC patients who have received 1-2 prior TKIs was undertaken. Using a classic 3+3 design, the phase I component of this study enrolled 12 subjects at 4 dose levels of BNC105P (4.2, 8.4, 12.6 and 16 mg/m2; IV infusion Days 1 & 8, 21-day repeating cycle). Everolimus was administered concurrently (10 mg p.o.). PK analysis was performed during Cycle 1.

Results: In the clinic the BNC105P / everolimus combination was well tolerated and no DLTs were observed in any of the phase I patients. Toxicities deemed to be drug-related included single events of Grade 2 anemia, thrombocytopenia and mucositis. Of the 12 patients enrolled to the phase I, 7 remain on treatment. The medium number of cycles is 3 (range: 1–14) and 3 patients have been administered >6 cycles of treatment. The randomized phase II component of the study continues and will compare everolimus given in combination with BNC105P to a sequential approach (everolimus followed by BNC105P).

Conclusions: The MTD of BNC105P (16 mg/m2) can be combined with full dose everolimus and is being evaluated in the randomized phase II study.

Randomized phase II trial of maintenance sunitinib versus placebo following response to chemotherapy (CT) for patients (pts) with advanced urothelial carcinoma (UC)

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Background: UC response to CT is not durable. Angiogenesis may play a role in the progression of UC. We evaluated whether maintenance sunitinib delays progression after response to CT.

Methods: Pts with ECOG PS 0-2, adequate organ function, stable disease, partial or complete response (SD, PR, CR) after 4-6 cycles of CT for advanced UC were randomized to oral sunitinib 50 mg/day, 28 days on, 14 days off (6-week cycle) or placebo. Disease was assessed every 12 wks. At progression, placebo pts were offered open label sunitinib. Primary endpoint: progression rate at 6 months (ms); secondary endpoints: safety, objective response rate, survival, VEGF/sVEGFR2 serum level changes. Using a randomized selection design 42 pts/arm has 90% probability of selecting sunitinib if true reduction in 6-ms progression rate is 15% (from 50% to 35%).

Results: Study was closed early due to slow accrual. 54 pts with median age 69 years, median ECOG PS 1, 70% with bladder primary, 26 with SD, 23 with PR, 5 with CR to CT were randomized to sunitinib (26) or placebo (28). The median number of cycles was 2/arm (sunitinib 0-15, placebo 0-13). The 6-ms progression rate was 81% (95%CI 61-93%), median time-to-progression (TTP) 5 ms (0.3-22.2, 95%CI 2.4-6.3) for sunitinib and 75% (95%CI 55-89%), 2.7 ms (0.8-19.6, 95%CI 2.5-7.4) for placebo. Response rate in pts with SD at enrollment was 9% for sunitinib and 7% for placebo. Most common G3/4 AEs on sunitinib were diarrhea (15.4%/0%), fatigue (15.4%/3.8%), thrombocytopenia (15.4%/7.7%), hypertension (11.5%/0%). 16 placebo pts received sunitinib with best response 1 PR (6.25%), 6 SD (37.5%), 5 PD (31.25%); 4 not response evaluable. Median TTP was 3.4 ms (0.1-22, 95%CI 1.6-5.5). 11 pts had G3/4 AEs, 5 pts discontinued sunitinib due to AEs (4 related, 1 unrelated). Placebo pts had no change in VEGF/sVEGFR2 over time. Sunitinib pts had no change in VEGF but sVEGFR2 significantly decreased after 1 cycle (p<0.0001) and at progression (p=0.0002). VEGF/sVEGFR2 did not correlate with TTP.

Conclusions: Maintenance sunitinib was feasible but did not improve 6-ms progression rate; open label sunitinib had limited activity. sVEGFR-2 decreased on sunitinib.