Evaluating atezolizumab in patients with urinary tract squamous cell carcinoma (AURORA): study protocol for a single arm, open-label, multicentre, phase II clinical trial

BACKGROUND

Bladder and urinary tract cancers account for approximately 21,000 new diagnoses and 5,000 deaths annually in the UK. Approximately 90% are transitional cell carcinomas where advanced disease is treated with platinum based chemotherapy and PD-1/PD-L1 directed immunotherapy. Urinary tract squamous cell carcinoma (UTSCC) accounts for about 5% of urinary tract cancers overall making this a rare disease. We have yet to establish definitive systemic treatment options for advanced UTSCC. Preliminary translational data, from UTSCC patient tumour samples, indicate high PD-L1 expression and tumour infiltrating lymphocytes in a proportion of cases. Both of these features are associated with differential gene expression consistent with a tumour/immune microenvironment predicted to be susceptible to immune checkpoint directed immunotherapy which we will evaluate in the AURORA trial.

METHODS

AURORA is a single arm, open-label, multicentre,UK phase II clinical trial. 33 patients will be recruited from UK secondary care sites. Patients with UTSCC, suitable for treatment with palliative intent, will receive atezolizumab PD-L1 directed immunotherapy (IV infusion, 1680 mg, every 28 days) for one year if tolerated. Response assessment, by cross sectional imaging will occur every 12 weeks. AURORA uses a Simon's 2-stage optimal design with best overall objective response rate (ORR, by RECIST v1.1) at a minimum of 12 weeks from commencing treatment as the primary endpoint. Secondary endpoints will include overall survival, progression-free survival, duration of response, magnitude of response using waterfall plots of target lesion measurements, quality of life using the EORTC QLQ-C30 tool, safety and tolerability (CTCAE v5) and evaluation of potential biomarkers of treatment response including PD-L1 expression. Archival tumour samples and blood samples will be collected for translational analyses.

DISCUSSION

If this trial shows atezolizumab to be safe and effective it may lead to a future late phase randomised controlled trial in UTSCC. Ultimately, we hope to provide a new option for treatment for such patients.

TRIAL REGISTRATIONS

EudraCT Number: 2021-001995-32 (issued 8th September 2021); ISRCTN83474167 (registered 11 May 2022); NCT05038657 (issued 9th September 2021).

Overall Survival Update for Patients with Metastatic Castration-resistant Prostate Cancer Treated with Capivasertib and Docetaxel in the Phase 2 ProCAID Clinical Trial

The PI3K/AKT/PTEN pathway is frequently deregulated in metastatic castration-resistant prostate cancer (mCRPC). ProCAID was a phase 2 trial assessing addition of the AKT1/2/3 inhibitor capivasertib to docetaxel for patients with mCRPC. We previously reported that capivasertib did not extend a composite progression-free survival primary endpoint but did significantly improve the secondary endpoint of overall survival (OS). Here we present OS data after 66% of events had occurred in the intent-to-treat population (n = 150). Median OS was 25.3 mo for capivasertib plus docetaxel versus 20.3 mo for placebo plus docetaxel (hazard ratio [HR] 0.70, 95% confidence interval [CI] 0.47-1.05; nominal p = 0.09). Receipt of subsequent life-extending treatments was balanced between the treatment arms. The OS benefit associated with capivasertib was maintained in a subset of patients previously treated with abiraterone and/or enzalutamide (median OS 25.0 vs 17.6 mo; HR 0.57, 95% CI 0.36-0.91; nominal p = 0.02) but not in abiraterone/enzalutamide-naïve patients (median OS 31.1 mo vs not reached; HR 1.43, 95% CI 0.63-3.23). We conclude that OS may be extended by addition of capivasertib to docetaxel. Exploratory analysis revealed that the OS benefit was maintained in a subset of patients previously exposed to androgen receptor-targeted agents, which should be evaluated in prospective trials. PATIENT SUMMARY: The ProCAID study examined whether adding the AKT inhibitor drug capivasertib to docetaxel chemotherapy improves outcomes for patients with advanced prostate cancer. Initial analysis of the ProCAID results suggested that capivasertib improved overall survival benefit. This follow-up analysis suggests that capivasertib addition may be particularly beneficial for patients whose cancer was previously treated with drugs that target the androgen receptor.

Updated overall survival (OS) analysis for ProCAID: A randomized, double-blind, placebo-controlled phase II trial of capivasertib with docetaxel versus docetaxel alone in metastatic castration-sensitive prostate cancer (mCRPC)

108

Background: The AKT pathway is frequently deregulated in mCRPC. ProCAID tested addition of capivasertib, a potent selective inhibitor of all three AKT isoforms (AKT1/2/3) to docetaxel chemotherapy vs. placebo plus docetaxel for mCRPC. The primary analysis showed no difference between treatment arms for the primary endpoint of composite progression free survival (cPFS). However, OS, which was a secondary endpoint, was extended in the capivasertib plus docetaxel arm. cPFS and OS results were consistent irrespective of PI3K/AKT/PTEN pathway biomarker status (Crabb et al, J Clin Oncol 2021;39(3):190-201). Methods: An updated analysis of mature OS data was undertaken once events reached ≥65% by Cox proportional hazards model, adjusted for minimisation factors, within the intent to treat (ITT) population (n = 150). Patients (pts) and investigators remained blinded to treatment allocation. We also investigated OS outcomes within subsets based on prior androgen receptor targeted agent (ARTA) exposure to abiraterone and/or enzalutamide (abi/enza) and the balance of post-trial life extending treatment use by treatment arm. Funding: Cancer Research UK (C9317/A16029, CRUK/12/042) and AstraZeneca. Results: At this OS update, 99 pts (66.0%) had died, with 88 of these deaths (88.9%) due to prostate cancer. 5 pts (3.3%) remained on capivasertib or placebo. Median OS was 25.3 months for the capivasertib plus docetaxel arm vs. 20.3 months for placebo plus docetaxel (hazard ratio (HR) 0.70, 95% confidence interval (CI) 0.47 to 1.05; nominal p = 0.09). One, or more, subsequent life extending treatment options, including abiraterone, enzalutamide, radium-223 and cabazitaxel, were received by 99 pts (66.0%) and were balanced between treatment arms (68% capivasertib, 64% placebo). 101 pts (67.3%; 51 capivasertib, 50 placebo) had received abi/enza prior to entering ProCAID. Within this subgroup, OS benefit for capivasertib plus docetaxel (median OS 31.1 months) was maintained vs. placebo plus docetaxel (median OS 19.3 months; HR 0.57, 95% CI 0.36 to 0.91), but not in the remaining 49 pts who were naive to prior abi/enza (median OS 31.1 vs. not reached respectively; HR 1.43, 95% CI 0.63 to 3.23). These updated OS results remained consistent irrespective of biomarker status for PI3K/AKT/PTEN pathway activation. No clinically significant differences from the previously reported safety outcomes were seen with extended follow up of this trial. Conclusions: OS remains longer within the ProCAID ITT population with the addition of capivasertib to docetaxel for mCRPC. This does not appear to be explained by subsequent treatment choices. Exploratory analysis found prolonged OS with capivasertib within a subset of pts previously exposed to an ARTA which should be evaluated in prospective trials. Clinical trial information: NCT02121639.

Phase I Trial of DNA Methyltransferase Inhibitor Guadecitabine Combined with Cisplatin and Gemcitabine for Solid Malignancies Including Urothelial Carcinoma (SPIRE)

PURPOSE

Preclinical data indicate that DNA methyltransferase inhibition will circumvent cisplatin resistance in various cancers.

PATIENT AND METHODS

SPIRE comprised a dose-escalation phase for incurable metastatic solid cancers, followed by a randomized dose expansion phase for neoadjuvant treatment of T2-4a N0 M0 bladder urothelial carcinoma. The primary objective was a recommended phase II dose (RP2D) for guadecitabine combined with gemcitabine and cisplatin. Treatment comprised 21-day gemcitabine and cisplatin cycles (cisplatin 70 mg/m2, i.v., day 8 and gemcitabine 1,000 mg/m2, i.v., days 8 + 15). Guadecitabine was injected subcutaneously on days 1-5, within escalation phase cohorts, and to half of 20 patients in the expansion phase. Registration ID: ISRCTN 16332228.

RESULTS

Within the escalation phase, dose-limiting toxicities related predominantly to myelosuppression requiring G-CSF prophylaxis from cohort 2 (guadecitabine 20 mg/m2, days 1-5). The most common grade ≥3 adverse events in 17 patients in the dose-escalation phase were neutropenia (76.5%), thrombocytopenia (64.7%), leukopenia (29.4%), and anemia (29.4%). Addition of guadecitabine to gemcitabine and cisplatin in the expansion phase resulted in similar rates of severe hematologic adverse events, similar cisplatin dose intensity, but modestly reduced gemcitabine dose intensity. Radical treatment options after chemotherapy were not compromised. Pharmacodynamics evaluations indicated guadecitabine maximal target effect at the point of cisplatin administration. Pharmacokinetics were consistent with prior data. No treatment-related deaths occurred.

CONCLUSIONS

The guadecitabine RP2D was 20 mg/m2, days 1-5, in combination with gemcitabine and cisplatin and required GCSF prophylaxis. Gene promoter methylation pharmacodynamics are optimal with this schedule. Addition of guadecitabine to gemcitabine and cisplatin was tolerable, despite some additional myelosuppression, and warrants further investigation to assess efficacy.

DNA methyltransferase inhibitor guadecitabine combined with cisplatin and gemcitabine chemotherapy (SPIRE): Randomized expansion phase as neoadjuvant therapy for bladder urothelial carcinoma

447

Background: Pre-clinical data support a hypothesis that DNA methyltransferase inhibition will circumvent cisplatin resistance in various cancers including urothelial carcinoma (UC). SPIRE comprised a previously reported phase Ib dose escalation phase for incurable metastatic solid cancers which established a recommended phase II dose (RP2D) for guadecitabine combined with gemcitabine and cisplatin (GC) chemotherapy (Crabb et al, ESMO Congress 2018, abstract 425P). We now report the SPIRE phase IIa randomised dose expansion phase which tested neoadjuvant treatment of bladder UC. Methods: Patients had T2-4a N0 M0 bladder UC intended for radical treatment. All patients received an investigator choice of 3 or 4 planned, 21-day, GC cycles (cisplatin 70 mg/m2, IV, day 8; gemcitabine 1000 mg/m2, IV, days 8 and 15). 20 patients were randomised (1:1, open label) to whether they also received guadecitabine 20 mg/m2, SC, on days 1 to 5, and G-CSF prophylaxis 300 µg, SC, on days 15 to 21. The primary objective for the expansion phase was to confirm a safe and biologically effective dose and schedule for this combination for future investigation. Circulating cell free DNA LINE-1 promotor methylation was measured as a guadecitabine pharmacodynamic endpoint. Trial registration: ISRCTN 16332228. Funding: Cancer Research UK, Astex Pharmaceuticals. Sponsor: University Hospital Southampton NHS Foundation Trust. Results: Median age was 68 (interquartile range (IQR) 59-72). 19 (95%) patients were male and 17 (85%) had T2 stage. The commonest grade ≥3 adverse events were neutropenia and thrombocytopenia with one or both affecting 6 (60%) patients in each treatment arm (no grade 5 events). One episode of neutropenic fever occurred (guadecitabine arm). Addition of guadecitabine to GC, versus GC alone, resulted in similar cisplatin dose intensity (median total doses 408 mg (IQR 384-435 mg) and 435 mg (IQR 384-435 mg) respectively) but modestly reduced gemcitabine dose intensity (median total doses 10,450 mg (IQR 9,500-11,400) and 12,768 mg (IQR 9,500-12,768) respectively). All patients completed post-chemotherapy radical treatment (8 cystectomy, 2 radiotherapy, in each arm) with similar timing post chemotherapy and peri-operative morbidity scores. LINE-1 promotor methylation depletion occurred at cycle day 8 in guadecitabine treated patients. Conclusions: Guadecitabine in combination with GC and G-CSF is safe and tolerable in this combination compared to GC alone as neoadjuvant treatment for UC. Radical surgery or radiotherapy delivery, and cisplatin dose intensity, were not compromised. Pharmacodynamic endpoints are optimal with this treatment schedule. Addition of guadecitabine to GC warrants further investigation. Clinical trial information: 16332228.

Pan-AKT Inhibitor Capivasertib With Docetaxel and Prednisolone in Metastatic Castration-Resistant Prostate Cancer: A Randomized, Placebo-Controlled Phase II Trial (ProCAID)

PURPOSE

Capivasertib is a pan-AKT inhibitor. Preclinical data indicate activity in metastatic castration-resistant prostate cancer (mCRPC) and synergism with docetaxel.

PATIENTS AND METHODS

ProCAID was a placebo controlled randomized phase II trial in mCRPC. Patients received up to ten 21-day cycles of docetaxel (75 mg/m2 intravenous, day 1) and prednisolone (5 mg twice daily, oral, day 1-21) and were randomly assigned (1:1) to oral capivasertib (320 mg twice daily, 4 days on/3 days off, from day 2 each cycle), or placebo, until disease progression. Treatment allocation used minimization factors: bone metastases; visceral metastases; investigational site; and prior abiraterone or enzalutamide. The primary objective, by intention to treat, determined if the addition of capivasertib prolonged a composite progression-free survival (cPFS) end point that included prostate-specific antigen progression events. cPFS and overall survival (OS) were also assessed by composite biomarker subgroup for PI3K/AKT/PTEN pathway activation status.

RESULTS

One hundred and fifty patients were enrolled. Median cPFS was 7.03 (95% CI, 6.28 to 8.25) and 6.70 months (95% CI, 5.52 to 7.36) with capivasertib and placebo respectively (hazard ratio [HR], 0.92; 80% CI, 0.73 to 1.16; one-sided P = .32). Median OS was 31.15 (95% CI, 20.07 to not reached) and 20.27 months (95% CI, 17.51 to 24.18), respectively (HR, 0.54; 95% CI, 0.34 to 0.88; two-sided P = .01). cPFS and OS results were consistent irrespective of PI3K/AKT/PTEN pathway activation status. Grade III-IV adverse events were equivalent between arms (62.2%). The most common adverse events of any grade deemed related to capivasertib were diarrhea, fatigue, nausea, and rash.

CONCLUSION

The addition of capivasertib to chemotherapy did not extend cPFS in mCRPC irrespective of PI3K/AKT/PTEN pathway activation status. The observed OS result (a secondary end point) will require prospective validation in future studies to address potential for bias.

ProCAID: A randomized double-blind phase II clinical trial of capivasertib (C) in combination with docetaxel and prednisolone chemotherapy (DP) in metastatic castration-resistant prostate cancer (mCRPC)

5520

Background: DP extends survival in mCRPC, but clinical benefit is modest. PI3K/AKT/PTEN pathway activation is common in mCRPC contributing to disease progression and DP resistance. C is a pan-AKT inhibitor. Pre-clinical data indicate activity in prostate cancer and synergism with DP. This phase II trial combined C with DP in mCRPC. Methods: Key eligibility criteria: histologically or cytologically proven measurable or evaluable mCRPC, suitable for treatment with DP for PSA and/or radiographic disease progression, ECOG performance status 0-1, no prior chemotherapy for mCRPC, not requiring insulin or > 2 oral hypoglycaemic drugs for diabetes mellitus. Treatment: up to 10 cycles of DP (D: 75 mg/m2 IV, day 1; P: 5 mg bd oral, day 1 – 21) and random assignment (1:1, double blind) to oral C (320 mg twice daily, 4 days on/3 days off, from cycle 1, day 2) or matched placebo to disease progression. Primary endpoint: progression free survival (PFS; comprising PSA, radiographic or clinical progression, new cancer therapy or death; PCWG2 criteria) in the intent to treat (ITT) population. Secondary endpoints included overall survival (OS) and safety. PFS and OS were also assessed by composite biomarker (B) subgroup for PI3K/AKT/PTEN pathway activation status (NGS/IHC on archival tumour, contemporaneous ctDNA). Statistics: designed to detect a 50% increase in median PFS (6 to 9 months (mo)) between the placebo and C arms (90% power, 20% 1-sided alpha) by Cox proportional hazards model. Registration: ISRCTN 69139368. Results: 150 patients were randomised to 01/2019. Median follow up 16.77 months (IQR 12.0-26.5). PFS and OS by ITT and B status, are shown in the table (NR, not reached; CI confidence interval). Grade 3–4 adverse events (AE) were equally common between arms (62.2%). The most common AEs were diarrhoea, fatigue and nausea. Conclusions: Adding C to DP did not extend PFS. The OS secondary endpoint was significantly increased. PFS and OS results were consistent irrespective of PI3K/AKT/PTEN pathway activation status. Clinical trial information: 69139368 . [Table: see text]

Response to guadecitabine (SGI-110) combined with cisplatin and gemcitabine (GCG) in platinum refractory germ cell tumors (GCTs)

e17057

Background: Treatment options for platinum refractory GCTs are limited. Platinum resistance derives, in part, from tumour suppressor gene promotor methylation. In vitro, this reverses on co-administration of a DNA hypomethylating agent. Guadecitabine is a next generation hypomethylating agent. SPIRE is a phase Ib/IIa clinical trial to establish a GCG dose/schedule. Methods: We report 2 platinum refractory GCT patients (pts) treated (txd) in SPIRE with GCG (guadecitabine 20 mg/m2, SC, day (D) 1-5; cisplatin 70 mg/m2, IV, D8; gemcitabine 1000 mg/m2, IV, D8 + 15; filgrastim 300 μg, SC, D15-21; q21). Results: Pt 1: 21 yo man, testicular mixed GCT (seminoma/malignant teratoma intermediate). Prior tx: 2001, orchidectomy; 2005, 3 x BEP (bleomycin, etoposide, cisplatin) + retroperitoneal lymph node dissection. 2015, 2 x TI (paclitaxel, ifosfamide), 3 x TIP (cisplatin, ifosfamide, paclitaxel); 2016, 3 x HDCE (high dose carboplatin/ etoposide + autologous stem cell transplantation); 2017, 6 x GOP (gemcitabine, oxaliplatin, paclitaxel). In 2017, received 6 x GCG in SPIRE for CT confirmed lung metastases (mets) and rising β-hCG (human chorionic gonadotropin). Response: RECIST stable disease with metabolic CR on PET in lungs and > 90% β-hCG reduction. In Cycle 6, pt developed symptomatic brain mets, treated with WBRT (40Gy, 20#) + cyberknife to the six mets completed 2018. Since 2018, ongoing complete marker and radiologic (brain and systemic) remission (20 months). Pt 2: 44 yo man, primary mediastinal non-seminomatous GCT. Prior tx: 2008, 4 x BEP + mediastinal mass resection; 2015, 4 x TIP; 2016, 1 x HDCE. In 2017, received 5 x GCG in SPIRE for a PET avid mediastinal/pulmonary relapse and AFP (alpha-fetoprotein) rise. Response: RECIST stable and > 50% AFP reduction for 6 months (subsequent progression with intracerebral metastasis). Treatment was well tolerated. Grade 4 neutropenia/ thrombocytopenia occurred in both and febrile neutropenia in pt 1. Both required a 25% dose reduction in Cis/Gem. Conclusions: GCG produced exceptional clinical responses in both platinum refractory GCT pts. Prospective evaluation is warranted. Clinical trial information: 16332228.

SPIRE - combining SGI-110 with cisplatin and gemcitabine chemotherapy for solid malignancies including bladder cancer: study protocol for a phase Ib/randomised IIa open label clinical trial

BACKGROUND

Urothelial bladder cancer (UBC) accounts for 10,000 new diagnoses and 5000 deaths annually in the UK (Cancer Research UK, http://www.cancerresearchuk.org/health-professional/cancer-statistics/statistics-by-cancer-type/bladder-cancer , Cancer Research UK, Accessed 26 Mar 2018). Cisplatin-based chemotherapy is standard of care therapy for UBC for both palliative first-line treatment of advanced/metastatic disease and radical neoadjuvant treatment of localised muscle invasive bladder cancer. However, cisplatin resistance remains a critical cause of treatment failure and a barrier to therapeutic advance in UBC. Based on supportive pre-clinical data, we hypothesised that DNA methyltransferase inhibition would circumvent cisplatin resistance in UBC and potentially other cancers.

METHODS

The addition of SGI-110 (guadecitabine, a DNA methyltransferase inhibitor) to conventional doublet therapy of gemcitabine and cisplatin (GC) is being tested within the phase Ib/IIa SPIRE clinical trial. SPIRE incorporates an initial, modified rolling six-dose escalation phase Ib design of up to 36 patients with advanced solid tumours followed by a 20-patient open-label randomised controlled dose expansion phase IIa component as neoadjuvant treatment for UBC. Patients are being recruited from UK secondary care sites. The dose escalation phase will determine a recommended phase II dose (RP2D, primary endpoint) of SGI-110, by subcutaneous injection, on days 1-5 for combination with GC at conventional doses (cisplatin 70 mg/m2, IV infusion, day 8; gemcitabine 1000 mg/m2, IV infusion, days 8 and 15) in every 21-day cycle. In the dose expansion phase, patients will be randomised 1:1 to GC with or without SGI-110 at the proposed RP2D. Secondary endpoints will include toxicity profiles, SGI-110 pharmacokinetics and pharmacodynamic biomarkers, and pathological complete response rates in the dose expansion phase. Analyses will not be powered for formal statistical comparisons and descriptive statistics will be used to describe rates of toxicity, efficacy and translational endpoints by treatment arm.

DISCUSSION

SPIRE will provide evidence for whether SGI-110 in combination with GC chemotherapy is safe and biologically effective prior to future phase II/III trials as a neoadjuvant therapy for UBC and potentially in other cancers treated with GC.

TRIAL REGISTRATION

EudraCT Number: 2015-004062-29 (entered Dec 7, 2015) ISRCTN registry number: 16332228 (registered on Feb 3, 2016).

The effect of intramolecular hydrogen bonding on the thermodynamics of partitioning of an isomer of the histamine H2-receptor antagonist metiamide

The thermodynamics of transfer from water to 1-octanol of the 4 and 5 substituted N-methylimidazole isomers of the H2-receptor antagonist metiamide have been determined. The isomers have similar free energies of transfer but the enthalpy and entropy of transfer of the 4-isomer are substantially greater than those of the 5-isomer. This indicates that the 4-isomer forms an intramolecular hydrogen bond in the polar octanol phase.