Long-term Outcomes of Chemoradiation for Muscle-invasive Bladder Cancer in Noncystectomy Candidates. Final Results of NRG Oncology RTOG 0524-A Phase 1/2 Trial of Paclitaxel + Trastuzumab with Daily Radiation or Paclitaxel Alone with Daily Irradiation

BACKGROUND

Chemo-radiation is a well-established alternative to radical cystectomy in patients with muscle-invasive bladder cancer. Many patients due to age or medical comorbidity are unfit for either radical cystectomy, or standard cisplatin- or 5-fluorouracil-based chemoradiation, and do not receive appropriate treatment with curative intent. We treated patients with a less aggressive protocol employing seven weekly doses of paclitaxel and daily irradiation. In those whose tumors showed overexpression of her2/neu, seven weekly doses of trastuzumab were also administered.

OBJECTIVE

To report the long-term survival outcomes and toxicity results of the of NRG Oncology RTOG 0524 study.

DESIGN, SETTING, AND PARTICIPANTS

Seventy patients were enrolled and 65 (median age: 76 yr) were deemed eligible. Patients were assigned to daily radiation and weekly paclitaxel + trastuzumab (group 1, 20 patients) or to daily radiation plus weekly paclitaxel (group 2, 45 patients) based on tumor her2/neu overexpression. Radiation was delivered in 1.8 Gy fractions to a total dose of 64.8 Gy.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

The primary endpoint was unresolved treatment-related toxicity. The secondary endpoints were complete response rate, protocol completion rate, and disease-free and overall survival.

RESULTS AND LIMITATIONS

Protocol therapy was completed by 60% (group 1) and 76% (group 2); complete response rates at 12 wk were 62% in each group. Acute treatment-related adverse events (AEs) of grade ≥3 were observed in 80% in group 1 and 58% in group 2. There was one treatment-related grade 5 AE in group 1. Unresolved acute treatment-related toxicity was 35% in group 1 and 31% in group 2. The median follow-up was 2.3 yr in all patients and 7.2 yr in surviving patients. Overall survival at 5 yr was 25.0% in group 1 and 37.8% in group 2 (33.8% overall). At 5 yr, disease-free survival was 15.0% in group 1 and 31.1% in group 2.

CONCLUSIONS

In a cohort of patients with muscle-invasive bladder cancer who are not candidates for cystectomy or cisplatin chemotherapy, chemoradiation therapy offers a treatment with a significant response rate and 34% 5-yr overall survival. While there were many AEs in this medically fragile group, there were few grade 4 events and one grade 5 event attributable to therapy.

PATIENT SUMMARY

Patients with invasive bladder cancer who cannot tolerate surgery were treated with radiation and systemic therapy without surgically removing their bladders. Most patients tolerated the treatment, were able to keep their bladders, and showed a significant treatment response rate.

Efficacy and safety of pembrolizumab in metastatic urothelial carcinoma: results from KEYNOTE-045 and KEYNOTE-052 after up to 5 years of follow-up

BACKGROUND

Immune checkpoint inhibitors are a standard therapy in metastatic urothelial carcinoma (UC). Long-term follow-up is necessary to confirm durability of response and identify further safety concerns.

PATIENTS AND METHODS

In KEYNOTE-045, patients with metastatic UC that progressed on platinum-containing chemotherapy were randomly assigned 1:1 to receive pembrolizumab or investigator's choice of paclitaxel, docetaxel, or vinflunine. Primary endpoints were progression-free survival per RECIST version 1.1 by blinded independent central review (BICR) and overall survival. In KEYNOTE-052, cisplatin-ineligible patients with metastatic UC received first-line pembrolizumab. The primary endpoint was objective response rate per RECIST version 1.1 by BICR.

RESULTS

A total of 542 patients (pembrolizumab, n = 270; chemotherapy, n = 272) were randomly assigned in KEYNOTE-045. The median follow-up was 62.9 months (range 58.6-70.9 months; data cut-off 1 October 2020). At 48 months, overall survival rates were 16.7% for pembrolizumab and 10.1% for chemotherapy; progression-free survival rates were 9.5% and 2.7%, respectively. The median duration of response (DOR) was 29.7 months (range 1.6+ to 60.5+ months) for pembrolizumab and 4.4 months (range 1.4+ to 63.1+ months) for chemotherapy; 36-month DOR rates were 44.4% and 28.3%, respectively. A total of 370 patients were enrolled in KEYNOTE-052. The median follow-up was 56.3 months (range 51.2-65.3 months; data cut-off 26 September 2020). The confirmed objective response rate was 28.9% (95% confidence interval 24.3-33.8), and the median DOR was 33.4 months (range 1.4+ to 60.7+ months); the 36-month DOR rate was 44.8%. Most treatment-related adverse events for pembrolizumab in either study were grade 1 or 2 and manageable, which is consistent with prior reports.

CONCLUSION

With ∼5 years of follow-up, pembrolizumab monotherapy continued to demonstrate durable efficacy with no new safety signals in patients with platinum-resistant metastatic UC and as first-line therapy in cisplatin-ineligible patients.

CLINICAL TRIAL REGISTRY AND ID

With ClinicalTrials.gov NCT02256436 (KEYNOTE-045); https://clinicaltrials.gov/ct2/show/NCT02256436 and NCT02335424 (KEYNOTE-052); https://clinicaltrials.gov/ct2/show/NCT02335424.

BMS-986158, a Small Molecule Inhibitor of the Bromodomain and Extraterminal Domain Proteins, in Patients with Selected Advanced Solid Tumors: Results from a Phase 1/2a Trial

This phase 1/2a, open-label study (NCT02419417) evaluated the safety, tolerability, pharmacokinetics (PK), and pharmacodynamics of BMS-986158, a selective bromodomain and extraterminal domain (BET) inhibitor. Dose escalation was performed with 3 BMS-986158 dosing schedules: A (5 days on, 2 days off; range, 0.75–4.5 mg), B (14 days on, 7 days off; 2.0–3.0 mg), and C (7 days on, 14 days off; 2.0–4.5 mg). Eighty-three patients were enrolled and received ≥1 BMS-986158 dose. Diarrhea (43%) and thrombocytopenia (39%) were the most common treatment-related adverse events (TRAEs). A lower incidence of TRAEs was found with schedules A (72%) and C (72%) vs. B (100%). Stable disease was achieved in 12 (26.1%), 3 (37.5%), and 9 (31.0%) patients on schedules A, B, and C, respectively. Two patients on schedule A with a 4.5-mg starting dose (ovarian cancer, n = 1; nuclear protein in testis [NUT] carcinoma, n = 1) experienced a partial response. BMS-986158 demonstrated rapid-to-moderate absorption (median time to maximum observed plasma concentration, 1–4 h). As expected with an epigenetic modifier, expression changes in select BET-regulated genes occurred with BMS-986158 treatment. Schedule A dosing (5 days on, 2 days off) yielded tolerable safety, preliminary antitumor activity, and a dose-proportional PK profile.

Abstract CT022: CheckMate 848: A randomized, open-label, phase 2 study of nivolumab in combination with ipilimumab or nivolumab monotherapy in patients with advanced or metastatic solid tumors of high tumor mutational burden

High tumor mutational burden assessed in tissue biopsies (tTMB-H) or blood (bTMB-H) is associated with clinical efficacy in patients treated with immunotherapies. CheckMate 848 (NCT03668119) is a prospective phase 2 study of nivolumab (NIVO) with or without ipilimumab (IPI) in patients with advanced or metastatic solid tumors that are tTMB-H or bTMB-H (≥ 10 mutations/megabase) who were immunotherapy-naive and refractory to standard local therapies.

The primary endpoint was objective response rate (ORR) in patients with tTMB-H or bTMB-H, assessed by FoundationOne® CDx-based and Clinical Trial Assays (Foundation Medicine), respectively. The study was not powered to compare NIVO + IPI vs NIVO. We present the interim and final analyses for the tTMB-H and bTMB-H cohorts, respectively (≥ 12 months follow-up, database lock June 2021).

Of 1954 screened patients, 212 were randomized 2:1 to NIVO 240 mg Q2W + IPI 1 mg/kg Q6W or NIVO 480 mg Q4W for ≤ 24 months, and 201 (135 tTMB-H; 147 bTMB-H) were refractory to standard therapies. Of > 40 tumor types, colorectal (10.8%), small-cell lung (7.5%), breast (7.1%), and uterine (7.1%) were the most common. ORR and survival outcomes with NIVO + IPI were improved in patients with tTMB-H. The responses were independent of bTMB-H status in the tTMB-H cohort but improved with tTMB-H status in the bTMB-H cohort (Table). The safety profile of NIVO + IPI was manageable, and clinical outcomes with NIVO were comparable with previous studies. The impact of TMB cutoff, PD-L1 expression, and microsatellite instability were explored.

In conclusion, NIVO + IPI demonstrated clinical efficacy with a manageable safety profile in patients with advanced or metastatic solid tumors that are tTMB-H or bTMB-H and refractory to standard therapies, with increased efficacy observed in patients with tTMB-H.

NIVO + IPI tTMB-H cohort bTMB-H cohorta Patients, n (%)b,c 68 (32.1) 80 (37.7) Number of prior treatments, median (range) 2 (0–7) 2 (1–9) ORR, n (%)c, 95% CI 24 (35.3), 24.1–47.8 18 (22.5), 13.9–33.2 ORR in patients with bTMB-H by tTMBc: < 10 mut/Mb (n = 31), n (%), 95% CI NA 3 (9.7), 2.0–25.8 ≥ 10 mut/Mb (n = 39), n (%), 95% CI NA 13 (33.3), 19.1–50.2 ≥ 10 to < 16 mut/Mb (n = 18), n (%), 95% CI NA 3 (16.7), 3.6–41.4 ≥ 16 mut/Mb (n = 21), n (%), 95% CI NA 10 (47.6), 25.7–70.2 ORR in patients with tTMB-H by bTMBc: < 10 mut/Mb (n = 20), n (%), 95% CI 7 (35.0), 15.4–59.2 NA ≥ 10 mut/Mb (n = 43), n (%), 95% CI 16 (37.2), 23.0–53.3 NA ≥ 10 to < 16 mut/Mb (n = 12), n (%), 95% CI 3 (25.0), 5.5–57.2 NA ≥ 16 mut/Mb (n = 31), n (%), 95% CI 13 (41.9), 24.5–60.9 NA Percentage of responders (≥ 9 months) (95% CI) 91 (68–98) 88 (61–97) Median PFS, months (95% CI)c 4.1 (2.8–11.3) 2.8 (2.3–3.0) Median OS, months (95% CI)c 14.5 (7.7–NE) 8.5 (5.8–10.5) aThe bTMB cohort was randomized prior to December 20, 2019. bOut of 212 randomized patients; data presented in this table are from patients who were refractory to standard therapies. cMinimum follow-up 12 months. bTMB, blood tumor mutational burden; NA, not applicable; NE, not evaluable; PFS, progression-free survival; OS, overall survival; tTMB, tissue tumor mutational burden.

Citation Format: Michael Schenker, Mauricio Burotto, Martin Richardet, Tudor Ciuleanu, Anthony Goncalves, Neeltje Steeghs, Patrick Schöffski, Paolo A. Ascierto, Michele Maio, Iwona Lugowska, Lorena Lupinacci, Alexandra Leary, Jean-Pierre Delord, Julieta Grasselli, David S. Tan, Jennifer E. Friedmann, Jacqueline Vuky, Marina Tschaika, Ruta Slepetis, Georgia D. Kollia, Misena Pacius, Ning Huang, Parul Doshi, Jonathan Baden, Massimo Di Nicola. CheckMate 848: A randomized, open-label, phase 2 study of nivolumab in combination with ipilimumab or nivolumab monotherapy in patients with advanced or metastatic solid tumors of high tumor mutational burden [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr CT022.

Phase 1a/1b study of FOR46, an antibody drug conjugate (ADC), targeting CD46 in metastatic castration-resistant prostate cancer (mCRPC)

3001

Background: FOR46, a fully human antibody (ab) conjugated to monomethyl auristatin E (MMAE), targets a tumor selective epitope of CD46, which is highly expressed in mCRPC and treatment-emergent small cell neuroendocrine cancer (t-SCNC). CD46 is enriched in tumor cells upon treatment with androgen signaling inhibitors (ASI). Following dose escalation (Phase 1a), dose expansion was undertaken in 2 cohorts (Phase 1b): 1) Pts with de novo or t-SCNC and 2) pts with mCRPC without a t-SCNC component. Pts with adenocarcinoma enrolled in dose escalation and expansion are included in this analysis. Methods: Eligible pts had mCRPC, with progression on at least 1 ASI, with no prior chemotherapy for CRPC. Phase 1a pts received FOR46 0.1-3.0 mg/kg IV Q3 weeks (wks). The primary objectives in phase 1a were to assess adverse effects (AEs) and select the phase 1b dose; and in phase 1b to assess efficacy. For phase 1b, tumor biopsy in the CRPC setting for assignment to the 2 cohorts was required. CD46 expression was not required for inclusion in the expansion cohort, but was evaluated using a non-epitope specific CD46 polyclonal ab. Histology and CD46 expression were centrally reviewed. Results: Thirty-three pts were enrolled in phase 1a and 10 in phase 1b (including 6 treated in ph1a at the expansion dose or higher). Overall, 36 pts were treated at doses > 1.2 mg/kg. Following excess toxicity in pts with body mass indices > 30 (3 of 3 with Gr 4 neutropenia and 1 of 3 with Gr 3 fatigue at 2.4 mg/kg), further dosing was calculated using adjusted body weight (AJBW) rather than actual weight, allowing escalation to 3.0 mg/kg. The 2.7 mg/kg dose by AJBW was determined to be the MTD and phase 1b dose. The most common AEs at the 2.7 mg/kg dose were neutropenia (77% Gr 3 or 4), infusion reactions (37%, all < Gr 2), fatigue (31%, all < Gr 2) and peripheral neuropathy (24%, all < Gr 2)). Fourteen of 31 evaluable pts (45.2%) at > 1.2 mg/kg achieved a PSA50 response with 10 (32.3%) confirmed. Five pts were not evaluable for PSA response; 3 had no post-baseline PSA and 2 had baseline PSA < 1 ng/mL. The median duration of confirmed PSA50 response is >16 wks (range 6-48+ wks, with 4 ongoing at 12, 24, 25 and 48 wks). 18 pts had measurable lesions; 8 of 18 (44.4%) had tumor regression, with 4 (22.2%) confirmed partial responses (PR). The median duration of response is > 14 wks (range 9 -31+ weeks with 2 ongoing at 13 and 31 wks). Eight pts were evaluable for CD46 expression with a median H-score of 245 (range 0-300). Two pts with PRs had H-scores of 15 and 300; 4 with confirmed PSA50 had H-scores of 10, 15, 40 and 300. Conclusions: FOR46, a novel ADC targeting CD46, demonstrates clinical activity in mCRPC pts, with an acceptable safety profile, similar to other MMAE-containing ADCs. FOR46 merits further investigation in pts with mCRPC, alone and in combination with agents that enhance CD46 expression. Clinical trial information: NCT03575819.

Health-related quality of life (HRQoL) for patients with advanced/metastatic urothelial carcinoma (UC) enrolled in KEYNOTE-052 who are potentially platinum ineligible

4561

Background: Frontline cisplatin-based chemotherapy improves survival in patients (pts) with UC, but ̃50% are cisplatin-ineligible owing to poor performance status or comorbidity. The definition of platinum ineligibility is not standardized; hence, treatment decisions are almost solely made by clinical judgment. Pembrolizumab (pembro) showed antitumor activity and manageable toxicity as frontline therapy in 370 cisplatin-ineligible pts in the single arm, phase 2 KEYNOTE-052 trial (NCT02335424). We present effects of pembro on HRQoL of pts in KEYNOTE-052 who were potentially platinum ineligible in this exploratory analysis. Methods: Eligible pts for KEYNOTE-052 were adults with no prior systemic chemotherapy for advanced/metastatic UC, ECOG PS ≤2, and measurable disease per RECIST v1.1 by blinded independent central review. Pembro 200 mg IV was administered Q3W for up to 2 y. Clinical characteristics of frail pts (platinum ineligible) were identified by extensive review of real-world treatment patterns and relevant literature. Consequently, platinum ineligibility was defined as having an ECOG PS ≥2 plus ≥1 of the following: visceral disease, creatinine clearance < 60 mL/min, or age ≥80 y. HRQoL was assessed using the EORTC QLQ-C30 and EQ-5D-3L during the first 4 cycles, then every 2 cycles for 1 year or until treatment discontinuation (whichever occurred first), and at least 30 days after treatment discontinuation. Key end points were change from baseline per the QLQ-C30 global health status (GHS)/QoL score, QLQ-C30 physical functioning subscale, and EQ-5D visual analog scale (VAS). The minimum important difference (MID) was 10 for QLQ-C30 score change (improved: ≥10; stable: –10 to 10; deteriorated: –10 or less); MID for VAS score change was 7 (improved: ≥7; stable: –7 to 7; deteriorated: –7 or less). Results: Median age for 143 pts was 75 y (range, 34-91); 129 pts (90.2%) had visceral disease; 142 (99.3%) had ECOG PS 2; 1 had ECOG PS 3 (enrolled in error). Compliance rate for HRQoL questionnaires was 93.7% at baseline. At the prespecified analysis time of week 9, 77.6% of pts had improved (n = 51) or stable (n = 60) QLQ-C30 GHS/QoL scores, 64.3% had improved (n = 35) or stable (n = 57) QLQ-C30 physical functioning scores, and 62.2% had improved (n = 56) or stable (n = 33) EQ-5D VAS scores. These scores were stable throughout the HRQoL assessment period for pts who continued pembro. Conclusions: In this exploratory analysis, pembro maintained HRQoL for pts with advanced/metastatic UC in KEYNOTE-052 who were potentially platinum-ineligible per the above criteria. Together with the efficacy and safety data from KEYNOTE-052, these data suggest that pembro monotherapy is a valuable treatment option for select pts with advanced UC who are more senior and/or deemed medically frail. Clinical trial information: NCT02335424.

Trial in progress: Durvalumab and olaparib for the treatment of prostate cancer in men predicted to have a high neoantigen load

TPS5099

Background: Approximately 30% of patients (pts) treated with definitive surgical and/or radiation therapy for localized prostate adenocarcinoma develop biochemical recurrence (BCR). The optimal time to initiate androgen deprivation therapy (ADT) for such patients is controversial and depends on patient and provider preference, absolute PSA value, and PSA doubling time (PSADT), which has been associated with time to metastasis. Because the time from BCR to metastasis can be long in many cases, strategies allowing pts to avoid ADT while extending metastasis-free survival are desirable. Prior studies have shown that a high tumor neoantigen load correlates with response to anti-PD(L)1. We hypothesized that PARP inhibitor-induced genomic instability may sensitize tumors to anti-PD(L)1 through: i) increasing mutational burden and subsequent tumor neoantigen formation, and/or ii) through activation of other immunogenic pathways (e.g. the STING pathway). This trial investigates an ADT-sparing approach for men predicted to have high neoantigen load and who have BCR prostate cancer. Methods: This is a phase 2 clinical trial testing durvalumab (1500 mg IV every 4 weeks) and olaparib (300 mg PO twice a day) (one cycle = 4 weeks) in men with BCR (PSADT≤10 months) whose tumors are predicted to have high neoantigen load based on: biallelic CDK12 mutations (Cohort A), mismatch repair deficiency (MMRd)/high microsatellite instability (MSI-H) (Cohort B), or loss of function mutations in homologous recombination repair (HRR) genes (Cohort C). Cohorts A and B will receive 3 cycles of durvalumab followed by 3 cycles of the combination of durvalumab and olaparib. Given the proven efficacy of olaparib in prostate cancer patient whose tumors posses an HRR gene mutation, Cohort C will receive 6 full cycles of the combination. Ten patients will be enrolled in each cohort (total n = 30) at two collaborating sites. This study was designed to provide preliminary efficacy data across eligible cohorts, with a primary objective of estimating the proportion of pts with an undetectable PSA at 12 months within each cohort. Secondary objectives include safety, proportion of patients with ≥50% decline in PSA from baseline and quality of life measures. Correlative studies will assess blood and tissue molecular biomarkers for association with outcomes. The study is open with two patients enrolled at the time of abstract submission. Clinical trial information: NCT04336943.

Phase 2 study of the IDO/PD-L1-targeted immune-modulatory vaccine, IO102-IO103, plus pembrolizumab as first-line treatment for metastatic non–small cell lung cancer (NSCLC), squamous cell carcinoma of the head and neck (SCCHN), or urothelial bladder cancer (UBC)

TPS2699

Background: Immunotherapy has transformed the treatment of NSCLC and other solid tumors, such as SCCHN and UBC. However, even with standard-of-care anti-PD-1/PD-L1 therapies, few patients achieve durable benefit even when PD-L1 is overexpressed. IO102-IO103 is a potentially first-in-class, dual-antigen, immune-modulatory therapy that stimulates T cells to target tumoral immune escape via key checkpoint molecules IDO and PD-L1. It is thought that activating IDO/PD-L1-specific T cells in cancer patients through vaccination may support anticancer immunity by restricting immunosuppressive signaling and restoring the tumor immune microenvironment to render the tumor more susceptible to anti-PD-1 blockade. Thus there is a rationale for combining IO102-IO103 with anti-PD-1 therapy in the first-line treatment of metastatic tumors, such as NSCLC, SCCHN, or UBC. Combined IO102-IO103 and anti-PD-1 therapy (nivolumab) has already shown a robust signal of clinical activity (overall response rate [ORR], 80%; complete response rate [CRR], 43%; median progression-free survival [PFS], 26 months) and was well tolerated with minimal added toxicity to nivolumab in a Phase 1/2 study of anti-PD1-naïve patients with metastatic melanoma (Kjeldsen, et al. Nat Med 2021). Methods: This is a Phase 2, international, multicenter (US and Europe), non-comparative, open-label, multi-arm (basket) trial (EudraCT No. 2021-003026-69; ClinicalTrials.gov No. NCT05077709). Patients with recurrent, unresectable or metastatic solid tumors in 3 indications and no prior treatments for metastatic disease are being enrolled: NSCLC with a PD-L1 Tumor Proportion Score (TPS) ≥50% (Arm A); SCCHN with PD-L1 Combined Positive Scores (CPS) ≥20 (Arm B); or UBC with PD-L1 CPS ≥10 and not eligible for platinum-containing chemotherapy (Arm C). All patients, ̃30 in each arm, will receive 3-week cycles of IO102-IO103 (85-85 µg on Day [D] 1 and 8 of Cycle 1 and 2, and D1 thereafter) subcutaneously plus pembrolizumab (200 mg on D1) intravenously, for up to 2 years. Primary endpoints are ORR by RECIST v1.1 or 6-month PFS rate by investigator assessment (to be analyzed either 6 months after last patient started treatment or after target ORR is achieved, whichever is earliest). Secondary endpoints include PFS, duration of response, complete response rate, disease control rate, time to response, overall survival, and safety. Exploratory endpoints include biomarker and immune marker correlative studies, and PFS by iRECIST. The trial will assess the opportunity for a positive risk–benefit based on 2 efficacy boundaries for the ORR and 6-month PFS rate in each arm, with cohort expansion permitted if a clinically relevant efficacy signal is observed. Clinical trial information: EudraCT No. 2021-003026-69; ClinicalTrials.gov No. NCT05077709.

Pilot trial of physical and cognitive changes related to fall risk in enzalutamide patients with castration-resistant prostate cancer (CRPC)

e17018

Background: Advanced prostate cancer disproportionally affects older men (age ≥ 75 years). Despite representing only 26% of diagnoses, older men represent half of those diagnosed with metastatic disease and half of all prostate cancer deaths. Treatment options for CRPC include enzalutamide (enza), a competitive inhibitor of the androgen receptor, which shows improved overall survival and other cancer-specific responses in older men. However, enza is also reportedly associated with increased fall frequency of unclear pathophysiology. This pilot study examines strength, balance, and cognition in men before and 12 weeks after starting enza therapy for CRPC. Methods: This prospective single-arm study included men about to begin enza for CRPC, ≥ 65 years, able to ambulate independently. The following tests were administered at baseline and 12 weeks after initiation of enza: Sit-to-stand test (STS), Timed-Up-and-Go test, proprioception assessment, computerized dynamic posturography including sensory organization test (SOT), motor control test (MCT), and limits of stability; Functional Assessment of Cancer Therapy-Prostate, BPI-SF, Activities-specific Balance Confidence (ABC), Montreal Cognitive Assessment (MoCA), International Physical Activity Questionnaire (IPAQ), and the Godin leisure-time exercise questionnaire (GLTEQ). Falls were assessed with self-report fall diaries and calls from study team to participants over the course of 12 months. Results: Twenty-five participants enrolled. Median age was 75 years. There were 23 (92%) with both baseline and 12-week assessments, and 21 (84%) participants had complete falls data. From baseline to the 12-week follow up, ABC scale scores decreased (median 90.4 to 85.2), GLTEQ scale scores decreased (median 31.4 to 28.0), and time sitting per day from IPAQ increased (4 hours to 5 hours). Of those evaluable for falls, 15 (71%) did not fall during the 12 months and 6 (29%) fell at least once. The fallers and non-fallers did not differ with respect to age or MoCA scores at baseline and on re-assessment. Those who fell performed more poorly on the STS test, the ABC and the dynamic posturography evaluations. Those who fell also had a higher level of activity by GLTEQ. Conclusions: This pilot study does not clearly elucidate the pathophysiology of falls in older men with CRPC taking enza but does provide useful and important guidance for the design of future studies in this area. Baseline and 12-week testing should be repeated at the 24-week time-point to allow for sufficient exposure to enza. To avoid confounding by practice effects, physical tests, particularly dynamic posturography, should be performed at least once prior to baseline assessment. Further research is needed to understand the mechanisms underlying the increased risk of falls previously observed in older men with CPRC taking enza.

Putative Biomarkers of Clinical Benefit With Pembrolizumab in Advanced Urothelial Cancer: Results from the KEYNOTE-045 and KEYNOTE-052 Landmark Trials

PURPOSE

In an exploratory analysis, we investigated the association between programmed death ligand 1 (PD-L1), tumor mutational burden (TMB), T-cell-inflamed gene expression profile (TcellinfGEP), and stromal signature with outcomes of pembrolizumab in urothelial carcinoma (UC).

PATIENTS AND METHODS

Patients with advanced UC received first-line pembrolizumab 200 mg every 3 weeks in the single-arm phase II KEYNOTE-052 trial (NCT02335424) and salvage pembrolizumab 200 mg every 3 weeks or chemotherapy (paclitaxel/docetaxel/vinflunine) in the randomized phase III KEYNOTE-045 trial (NCT02256436). The association of each biomarker (continuous variable) with objective response rate (ORR), progression-free survival (PFS), and overall survival (OS) was evaluated using logistic regression (ORR) and Cox PH (PFS, OS), adjusted for ECOG PS; nominal P values were calculated without multiplicity adjustment (one-sided, pembrolizumab; two-sided, chemotherapy). Significance was prespecified at α = 0.05.

RESULTS

In KEYNOTE-052, PD-L1, TMB, and TcellinfGEP were significantly associated with improved outcomes; stromal signature was significantly associated with worse outcomes. In KEYNOTE-045, although findings for TMB and TcellinfGEP with pembrolizumab were consistent with those of KEYNOTE-052, PD-L1 was not significantly associated with improved outcomes, nor was stromal signature associated with worse outcomes with pembrolizumab; chemotherapy was not associated with outcomes in a consistent manner for any of the biomarkers. Hazard ratio (HR) estimates at prespecified cutoffs showed an advantage for pembrolizumab versus chemotherapy regardless of PD-L1 or TMB, with a trend toward lower HRs in the combined positive score ≥10 and the TMB ≥175 mutation/exome subgroup. For TcellinfGEP, PFS and OS HRs were lower in the TcellinfGEP-nonlow subgroup regardless of treatment.

CONCLUSIONS

Multiple biomarkers characterizing the tumor microenvironment may help predict response to pembrolizumab monotherapy in UC, and potential clinical utility of these biomarkers may be context-dependent.

Post hoc pooled analysis of first-line (1L) pembrolizumab (pembro) for advanced urothelial carcinoma (UC): Outcomes by response at week nine in KEYNOTE-052 and KEYNOTE-361

519

Background: Pembro is a 1L treatment for cisplatin-ineligible pts with UC. This post hoc landmark analysis evaluated clinical outcomes by response at 9 wk to 1L pembro monotherapy in pts with advanced/unresectable or metastatic UC from the single-arm phase 2 KEYNOTE-052 (NCT02335424) and the randomized phase 3 KEYNOTE-361 (NCT02853305) trials. Methods: Cisplatin-ineligible pts with advanced UC were enrolled in KEYNOTE-052 and received pembro (200 mg Q3W for ≤2 y). Platinum-eligible pts with advanced UC who had not previously received systemic chemotherapy (chemo) were enrolled in KEYNOTE-361 and randomly assigned 1:1:1 to receive pembro (200 mg Q3W for ≤2 y), pembro + chemo (1000 mg/m2 gemcitabine on d1 and d8 + cisplatin [70 mg/m2] or carboplatin [AUC 5] on d1 of each 3-wk cycle), or chemo. The primary analysis group included pembro monotherapy–treated pts; the sensitivity analysis group included pembro monotherapy–treated pts from KEYNOTE-052 and the choice of carboplatin subpopulation of pembro monotherapy–treated pts from KEYNOTE-361. Landmark analyses of OS by pts with CR, PR, SD, or PD per RECIST v1.1 by BICR at first imaging assessment (wk 9) were pooled for the ITT populations. Duration of CR/PR/SD and OS were estimated using the Kaplan-Meier method. Data cutoffs were Sep 26, 2020 (KEYNOTE-052) and Apr 29, 2020 (KEYNOTE-361). Results: The primary analysis group included 681 pembro-treated pts (KEYNOTE-052, N = 374; KEYNOTE-361, N = 307); the sensitivity analysis group included 544 pembro-treated pts (KEYNOTE-052, N = 374; KEYNOTE-361, N = 170). Median time from randomization to cutoff was 51.9 mo (range, 22.0-65.3) and 53.7 mo (range, 22.0-65.3) for the primary and sensitivity analysis groups, respectively. Twenty-five pts (4.6%) had CR and 135 (24.6%) had PR (primary group); 17 pts (3.9%) had CR and 105 (24.1%) had PR (sensitivity group). Median DOR was 25.9 mo for pts with CR/PR at wk 9; pts with CR/PR or SD at wk 9 had longer OS than pts with PD at wk 9 (Table). Conclusions: In this post hoc analysis, pts with advanced UC in KEYNOTE-052 and KEYNOTE-361 with CR/PR at wk 9 had better clinical outcomes with pembro monotherapy than pts with SD or PD; 1L pembro monotherapy continues to show efficacy in advanced UC. Clinical trial information: NCT02335424 and NCT02853305. [Table: see text]

Impact of primary tumor location on efficacy and safety of pembrolizumab (pembro) in patients (pts) with locally advanced or metastatic urothelial carcinoma (UC) enrolled in the phase 2 KEYNOTE-052 and phase 3 KEYNOTE-045 trials

516

Background: Pembro showed antitumor activity in 1L and 2L for pts with UC in the single-arm, phase 2 KEYNOTE-052 study (NCT02335424) and the randomized phase 3 KEYNOTE-045 (NCT02256436) study, respectively. This post hoc exploratory analysis evaluated whether primary tumor location affected efficacy and safety of pembro (KEYNOTE-052; KEYNOTE-045) and chemotherapy (chemo; KEYNOTE-045). Methods: KEYNOTE-052 enrolled cisplatin-ineligible pts with advanced/metastatic UC who had not previously received systemic therapy; they received pembro (200 mg IV Q3W). KEYNOTE-045 enrolled pts with advanced/metastatic UC who had received platinum-containing chemo; pts were randomly assigned 1:1 to receive pembro (200 mg IV Q3W) or investigator’s choice of chemo (paclitaxel, docetaxel, or vinflunine). Both studies required pts to have measurable disease per RECIST v1.1. Upper tract (UT) UC included primary tumors in the renal pelvis or ureter; lower tract (LT) UC included primary tumors in the bladder or urethra. Pts with UT and LT disease (UT/LT) were classified as LT. Pts receiving pembro were treated until disease progression, unacceptable toxicity, or withdrawal of consent, for up to 2y. End points were PFS, ORR, and DOR per RECIST v1.1 by central radiology assessment and OS. Results: A total of 369 pembro-treated pts (68 UT; 301 LT [79 UT/LT]) from KEYNOTE-052 plus 270 pembro-treated pts (93 UT; 177 LT [33 UT/LT]) and 272 chemo-treated pts (94 UT; 178 LT) from KEYNOTE-045 were evaluated. Median follow-up from randomization to data cutoff (09/26/20 and 10/1/20, respectively) was ≥56 mo. Both studies enrolled a similar percentage of pts with PD-L1–positive tumors (25%-30%). PFS, ORR, DOR, and OS for pembro were consistent regardless of tumor location, although ORR for KEYNOTE-045 was lower for the UT group (Table). In the chemo arm of KEYNOTE-045, similar efficacy was observed regardless of tumor location or regimen. Grade 3-5 TRAEs occurred at similar rates in KEYNOTE-052 (19.1% UT; 21.6% LT) and KEYNOTE-045 (17.2% UT; 16.8% LT). Conclusions: In this exploratory analysis, pembro showed similar clinical activity and manageable safety regardless of primary UC tumor location. Clinical trial information: NCT02256436 and NCT02335424. [Table: see text]

Post hoc analysis of the efficacy of pembrolizumab retreatment after progression of advanced urothelial carcinoma (UC) in KEYNOTE-045 and KEYNOTE-052

512

Background: Pembrolizumab (pembro) has shown efficacy in advanced/unresectable and metastatic UC (mUC). There is interest in determining whether pts should be treated subsequently with checkpoint inhibitors such as anti–PD-1 therapy if mUC responds then later progresses. Pembro retreatment after disease progression has shown efficacy in melanoma and NSCLC. This post hoc exploratory analysis investigated the efficacy of pembro retreatment for pts with advanced UC or mUC enrolled in KEYNOTE-045 and KEYNOTE-052 with a best overall response (BOR) of SD or better and whose disease progressed after discontinuation or completion of 2 y of therapy. Methods: The phase 3 KEYNOTE-045 trial (NCT02256436) was designed to compare the efficacy and safety of pembro vs chemotherapy (chemo) in pts with mUC that recurred/progressed on platinum containing chemo; ≤2 prior lines of systemic chemo for mUC were permitted. The phase 2 KEYNOTE-052 trial (NCT02335424) was designed to evaluate the efficacy and safety of first-line pembro in cisplatin-ineligible pts with advanced UC. In both studies, pembro was administered for up to 2 y; pts were eligible for retreatment if they stopped pembro after CR or had a BOR of CR, PR, or SD and completed 2 y of treatment. Pts must have investigator-confirmed radiographic PD after therapy cessation, have ECOG PS score 0-1, and not have received anticancer treatment after the last pembro dose. BOR to retreatment is reported. Results: At data cutoff for KEYNOTE-045 (Oct 1, 2020), 11 pts were retreated: 5 (45%) achieved objective response to retreatment (3 CR; 2 PR; Table) and 6 had SD, for a disease control rate (DCR; CR+PR+SD) of 100%. Median treatment-free interval was 7.7 mo (IQR, 3.6-16.5); median duration of retreatment was 11.4 mo (IQR, 7.6-12.0). Seven pts (64%) were alive at cutoff. At data cutoff for KEYNOTE-052 (Sep 26, 2020), 10 pts were retreated; 5 (50%) had objective response to retreatment (1 CR; 4 PR) and 4 had SD, for a DCR of 90%. Retreatment BOR was PD for 1 pt (10%). Median treatment-free interval was 13.0 mo (9.2-16.6); median duration of retreatment was 6.0 mo (IQR, 4.9-9.2). Four pts (40%) were alive at cutoff. Conclusions: Although the number of pts who received retreatment was small, objective responses were observed. The findings are generally consistent with observations from retreatment in other tumor types (e.g., melanoma). Clinical trial information: NCT02256436 and NCT02335424. [Table: see text]

Phase 1/2 study of ARV-110, an androgen receptor (AR) PROTAC degrader, in metastatic castration-resistant prostate cancer (mCRPC)

17

Background: ARV-110 is a first-in-class, oral PROteolysis TArgeting Chimera (PROTAC) protein degrader that selectively targets AR. Patients (pts) with mCRPC have limited treatment (tx) options due to decreasing AR dependence of tumors upon successive therapies. Previous phase 1 data indicated clinical activity for ARV-110 in heavily pretreated pts with mCRPC and suggested enhanced activity in pts with specific molecular profiles, eg, AR T878 and H875 mutations, leading to a phase 2 expansion (ARDENT) to further characterize ARV-110 in biomarker-defined pt subgroups. We report results of the ongoing phase 1/2 study. Methods: In phase 1, pts with mCRPC and disease progression after ≥2 prior therapies (enzalutamide and/or abiraterone required) received ARV-110 orally once or twice daily (QD or BID) in sequential cohorts (3 + 3 dose escalation design). Primary objectives were to assess ARV-110 safety and select the recommended phase 2 dose (RP2D). Phase 2 pts with mCRPC and 1–2 prior novel hormonal agents (NHAs) ± chemotherapy were assigned to 3 biomarker-defined subgroups: 1) AR T878 and/or H875 mutations, 2) AR L702H mutation or AR-V7 (variants not degraded by ARV-110 in nonclinical studies), and 3) wild-type AR or other AR alterations. A fourth subgroup enrolled pts based on clinical history of less prior tx: ≤1 therapy for mCRPC, 1 NHA, and no chemotherapy. Primary objective is to assess ARV-110 antitumor activity. Results: As of Aug 26, 2021, 173 pts were enrolled (67 in phase 1; 106 in phase 2). In phase 1, ARV-110 doses ranged from 35–700 mg QD or 210–420 mg BID; 420 mg QD was selected as the RP2D based on safety, pharmacokinetics, and efficacy. Across 140 biomarker-evaluable phase 1/2 pts with ≥1 month of prostate-specific antigen (PSA) follow-up, 26 with AR T878A/S and/or H875Y mutations had best PSA declines ≥50% (PSA50) and ≥30% (PSA30) of 46% and 58%, respectively, vs 10% and 23% in 114 pts without these mutations. Of 7 RECIST-evaluable pts with AR T878A/S and/or H875Y mutations, 6 had tumor shrinkage (2 with confirmed partial responses), and 4 remain on tx. Five of 19 (26%) PSA-evaluable pts in the fourth subgroup (only 1 prior NHA; no prior chemotherapy) achieved PSA50. Overall PSA50 and PSA30 response rates were 16% and 29%, respectively. There were no grade ≥4 tx-related adverse events (TRAEs) in 113 pts treated at the RP2D. The most common any grade TRAEs at the RP2D were nausea (42%; grade 3: 1%), fatigue (27%; grade 3: 1%), vomiting (23%; grade 3: 1%), decreased appetite (19%; grade 3: 0), diarrhea (15%; grade 3: 2%), and alopecia (11%). Conclusions: ARV-110, a novel AR protein degrader, demonstrates clinical activity in a post-NHA, heavily pretreated mCRPC pt population, with greatest PSA50 activity and RECIST responses in pts with AR T878 and/or H875 mutations, likely representing a particularly ARV-110–sensitive population. ARV-110 merits further investigation in pts with mCRPC. Clinical trial information: NCT0388861.

Trial in progress: Durvalumab and olaparib for the treatment of prostate cancer in men predicted to have a high neoantigen load

TPS202

Background: Approximately 30% of patients (pts) treated with definitive surgical and/or radiation therapy for localized prostate adenocarcinoma develop biochemical recurrence (BCR). The optimal time to initiate androgen deprivation therapy (ADT) for such patients is controversial and depends on patient and provider preference, absolute PSA value, and PSA doubling time (PSADT), which has been associated with time to metastasis. Because the time from BCR to metastasis can be long in many cases, strategies allowing pts to avoid ADT while extending metastasis-free survival are desirable. Prior studies have shown that a high tumor neoantigen load correlates with response to anti-PD(L)1. We hypothesized that PARP inhibitor-induced genomic instability may sensitize tumors to anti-PD(L)1 through: i) increasing mutational burden and subsequent tumor neoantigen formation, and/or ii) through activation of other immunogenic pathways (e.g. the STING pathway). This trial investigates an ADT-sparing approach for men predicted to have high neoantigen load and who have BCR prostate cancer. Methods: This is a phase 2 clinical trial testing durvalumab (1500 mg IV every 4 weeks) and olaparib (300 mg PO twice a day) (one cycle = 4 weeks) in men with BCR (PSADT≤10 months) whose tumors are predicted to have high neoantigen load based on: biallelic CDK12 mutations (Cohort A), mismatch repair deficiency (MMRd)/high microsatellite instability (MSI-H) (Cohort B), or loss of function mutations in homologous recombination repair (HRR) genes (Cohort C). Cohorts A and B will receive 3 cycles of durvalumab followed by 3 cycles of the combination of durvalumab and olaparib. Given the proven efficacy of olaparib in prostate cancer patient whose tumors posses an HRR gene mutation, Cohort C will receive 6 full cycles of the combination. Ten patients will be enrolled in each cohort (total n = 30) at two collaborating sites. This study was designed to provide preliminary efficacy data across eligible cohorts, with a primary objective of estimating the proportion of pts with an undetectable PSA at 12 months within each cohort. Secondary objectives include safety, proportion of patients with ≥50% decline in PSA from baseline and quality of life measures. Correlative studies will assess blood and tissue molecular biomarkers for association with outcomes. The study is open with two patients enrolled at the time of abstract submission. Clinical trial information: NCT04336943.

Multiomics analysis of serial PARP inhibitor treated metastatic TNBC inform on rational combination therapies

In a pilot study, we evaluated the feasibility of real-time deep analysis of serial tumor samples from triple negative breast cancer patients to identify mechanisms of resistance and treatment opportunities as they emerge under therapeutic stress engendered by poly-ADP-ribose polymerase (PARP) inhibitors (PARPi). In a BRCA-mutant basal breast cancer exceptional long-term survivor, a striking tumor destruction was accompanied by a marked infiltration of immune cells containing CD8 effector cells, consistent with pre-clinical evidence for association between STING mediated immune activation and benefit from PARPi and immunotherapy. Tumor cells in the exceptional responder underwent extensive protein network rewiring in response to PARP inhibition. In contrast, there were minimal changes in the ecosystem of a luminal androgen receptor rapid progressor, likely due to indifference to the effects of PARP inhibition. Together, identification of PARPi-induced emergent changes could be used to select patient specific combination therapies, based on tumor and immune state changes.

Combination Therapy With Immune Checkpoint Inhibitors in Urothelial Carcinoma: Current Data and Future Outlook

Bladder cancer is the sixth most common cancer in the United States, with an estimated 81,400 new cases in 2020. Although bladder cancer has 4 stages, for systemic treatment we recognize 3 clinical stages: non-muscle-invasive bladder cancer (NMIBC), muscle-invasive bladder cancer (MIBC), and locally advanced/metastatic urothelial carcinoma (mUC). Approximately 70% to 80% of patients present with NMIBC at diagnosis and have an excellent 5-year overall survival (OS) of 69.2% to 95.8%.1 About 10% to 15% of patients present with MIBC at the time of diagnosis and have about a 50% chance of progressing to metastatic disease.2 mUC accounts for 10% to 15% of all bladder cancers at diagnosis, with a 5-year OS for patients of fewer than 10% with platinum-based chemotherapy.

Clinical activity and safety of the RET inhibitor pralsetinib in patients with RET fusion-positive solid tumors: Update from the ARROW trial

3079

Background: RET fusions are targetable oncogenic drivers in multiple solid tumor types. ARROW study (NCT03037385) data supported the US FDA approval of pralsetinib, a once-daily (QD) oral highly potent and selective RET inhibitor, for RET-altered metastatic non-small cell lung cancer (NSCLC) and advanced/metastatic thyroid cancer. Here we provide an update on the clinical activity of pralsetinib in patients (pts) with advanced RET fusion-positive solid tumors other than NSCLC and thyroid cancer (“other” RET fusion–positive solid tumors). Methods: The global ongoing ARROW study (84 sites in 13 countries) includes phase 1 dose-escalation (30–600 mg [QD or twice daily]) and phase 2 expansion cohorts (400 mg QD) defined by tumor type and RET alteration status. Primary objectives are overall response rate (ORR; blinded independent central review per RECIST v1.1) and safety. Results: Updated analyses were completed as of Nov 6, 2020 (data cut-off) for 21 pts with other RET fusion–positive solid tumors enrolled by May 22, 2020 (enrollment cut-off) (lung other than NSCLC, n = 4; pancreatic, n = 3; colon, n = 3; cholangiocarcinoma, n = 3; unknown primary [UP], n = 2; other, n = 6). Overall, 11 (52%) pts received ≥2 prior lines of therapy for metastatic disease. The most common RET fusion partners were CCDC6 and KIF5B (24% each), NCOA4 (19%), other (10%), and unknown (24%). Two pts with colon cancer were excluded from efficacy analyses due to other driver mutations ( KRAS, PIK3CB). In 19 evaluable pts, ORR was 53% (95% CI, 29–76) with 2 (11%) complete responses (CR) and 8 (42%) partial responses (PR). Responses occurred across multiple tumor types including 3/3 pts with pancreatic cancer (including a CR ongoing at 20.8 months on treatment), 2/2 pts with UP, 2/3 pts with cholangiocarcinoma, and in pts with mesenchymal, salivary duct, and lung carcinoid tumors. Median duration of response was 19.0 months (95% CI, 5.5–not estimable). Clinical benefit rate (proportion with CR, PR, or stable disease persisting ≥16 weeks) was 68% (95% CI, 43–87). Tumor shrinkage was observed in 89% of 18 evaluable pts with post-baseline tumor assessment. In all pts enrolled in ARROW who received pralsetinib 400 mg QD irrespective of tumor type (n = 471) the most common (≥25%) treatment-related adverse events (TRAEs) were increased aspartate aminotransferase (39%), anemia (35%), increased alanine aminotransferase (28%), constipation (26%), and hypertension (25%). Overall, 6% of pts discontinued treatment due to TRAEs. Conclusions: Pralsetinib showed robust, durable antitumor activity in patients with multiple RET fusion‒positive, heavily pre-treated, advanced solid tumors, and was well tolerated. These data highlight the need for broad RET testing to identify candidates who could benefit from treatment with pralsetinib. Enrollment of patients with other RET fusion–positive solid tumors in ARROW is ongoing. Clinical trial information: NCT03037385.

First-line pembrolizumab (pembro) in cisplatin-ineligible patients with advanced urothelial cancer (UC): Response and survival results up to five years from the KEYNOTE-052 phase 2 study

4508

Background: Pembro was approvedfor cisplatin-ineligible patients with untreated advanced UC based on initial results of the phase 2 KEYNOTE-052 study (NCT02335424), which showed an ORR of 29%. Updated results after up to 5 years of follow-up are presented. Methods: KEYNOTE-052 is a single-arm, multi-site, open-label trial. Patients had advanced or metastatic UC, were cisplatin ineligible (criteria: ECOG PS 2, CrCl ≥30 to ̃60 mL/min, grade ≥2 peripheral neuropathy/hearing loss, NYHA class III heart failure), and had not previously received chemotherapy for advanced/metastatic disease. Patients received pembro 200 mg IV Q3W until progression, unacceptable toxicity, withdrawal, or 24 mo of therapy, whichever occurred first. PD-L1 status was determined by combined positive score (CPS, number of PD-L1–staining cells [tumor cells, lymphocytes, macrophages] divided by the total number of viable tumor cells, multiplied by 100); PD-L1–positive was CPS ≥10. The primary end point was confirmed ORR (RECIST v1.1, independent central review). Key secondary end points were duration of response (DOR), OS, and safety. Results: Among 370 enrolled patients, median age was 74 y, 315 (85.1%) had visceral disease, and 43 (11.6%) completed 24 mo of therapy. Median time from enrollment to data cutoff (Sep 26, 2020) was 56.3 mo (range, 51.2-65.3) for all patients and 56.0 mo (range, 51.4-65.2) for the 110 patients (29.7%) with CPS ≥10. Confirmed ORR for all patients was 28.9% (95% CI, 24.3-33.8); complete response, 9.5% (n=35); partial response, 19.5% (n=72). Median DOR was 33.4 mo (range, 1.4+ to 60.7+); 44.8% and 39.4% of patients had DOR ≥36 and ≥48 mo, (Kaplan-Meier estimates). Median OS was 11.3 mo (95% CI, 9.7-13.1); 24- and 36-mo OS rates were 31.5% and 22.1%. Patients with CPS ≥10 had better outcomes than patients with CPS <10 (Table). Treatment-related adverse events (AEs) occurred in 67.3% of patients; 21.1% of treatment-related AEs were grade ≥3, including 1 death (myositis). Conclusions: After up to 5 y of follow-up, pembro continued to elicit clinically meaningful, durable antitumor activity in cisplatin-ineligible patients with advanced UC. These effects were more pronounced in patients with CPS ≥10. Clinical trial information: NCT02335424. [Table: see text]

Abstract PD2-01: High Ki-67 as a biomarker for identifying patients with high risk early breast cancer treated in monarchE

Background monarchE, a phase 3, open-label, randomized study evaluating endocrine therapy with or without abemaciclib in patients with node positive, HR+, HER2-, high risk early breast cancer, resulted in a statistically significant improvement in invasive disease-free survival (IDFS) at a pre-planned interim analysis. Ki-67, a marker of cellular proliferation in breast cancer, was used in addition to other clinical and/or pathological features to identify patients whose cancer may be at higher risk of recurrence. A key secondary endpoint was to evaluate IDFS in patients with high (≥20%) Ki-67 tumors. Methods Patients with ≥4 positive nodes, or 1-3 nodes and either grade 3 disease, tumor size ≥5 cm, or central Ki-67 ≥20% were eligible for monarchE. Ki-67 was centrally assessed for all eligible patients with suitable untreated breast tissue using a standardized kit produced by Agilent/Dako (MIB-1). A sequential gatekeeping strategy was utilized to test the statistical significance in IDFS for patients with high Ki-67 tumors. Data on this subgroup are presented. Results Primary outcome results in the ITT population are presented separately and resulted in a significant 28.7% reduction in the risk of developing invasive disease with abemaciclib plus ET versus ET alone (HR = 0.713; 95% CI = 0.583, 0.871). Of the 5637 patients enrolled in monarchE, 4425 (78.5%) had Ki-67 samples eligible for testing. Of those tested, 2498 patients (56.5%) had Ki-67 ≥20% (Ki-67H). Results from the Ki-67H population are presented separately and showed that abemaciclib plus ET demonstrated superior IDFS versus ET alone with a 30.9% reduction in the risk of invasive disease (p=.0111; HR = 0.691; 95% CI = 0.519, 0.920). There was an absolute improvement of 4.5% in IDFS rate at 2 years (91.6% in the abemaciclib arm and 87.1% in the control arm). An additional planned analysis was performed evaluating efficacy in 2003 patients with high Ki-67 tumors enrolled in cohort 1 (patients with ≥4 positive nodes or 1-3 nodes and either tumor size ≥5 cm and/or grade 3 disease). The IDFS treatment benefit in this group was statistically significant with a HR of 0.643 (95% CI = 0.475, 0.872) corresponding to a 35.7% reduction in the risk of developing invasive disease. Two-year IDFS rates in this group were 91.3% in the abemaciclib group and 86.1% in the control arm, representing a 5.2% absolute improvement at 2 years. A clinically meaningful improvement was also observed in distant relapse-free survival (DRFS) in both populations. Baseline characteristics were balanced across arms in both Ki-67H populations. An exploratory analysis was conducted evaluating patients in cohort 1 with low Ki-67 (&lt;20%) and will be presented.

Conclusion This represents the first time a prespecified threshold of ≥20% for Ki-67 has been used to prospectively evaluate the utility of Ki-67 in a phase III registration trial with a standardized assay. There was a statistically significant improvement in IDFS for patients with high Ki-67 tumors across the ITT population (HR = 0.691) and in cohort 1 (HR = 0.643). These results suggest that Ki-67 ≥20% is an additional clinicopathological feature that can be used in conjunction with high risk features of nodal involvement, tumor size, and grade, to select patients with a higher risk of recurrence who may benefit from treatment with abemaciclib in the adjuvant setting. ClinicalTrials.gov: NCT03155997

Ki-67H Ki-67H Cohort 1EndpointAbemaciclib + ETN=1262ET aloneN=1236Abemaciclib + ETN=1017ET aloneN=986IDFS# events, n (%)82 (6.5)115 (9.3)71 (7.0)106 (10.8)log rank Pvalue, HR (95% CI)p=.0111 0.691 (0.519, 0.920)p=.00420.643 (0.475, 0.872)Rate (%) at 2-years (95% CI)91.6(89.4, 93.4)87.1(84.3, 89.5)91.3(88.9, 93.2)86.1(83.1, 88.7)DRFS# events, n (%)65 (5.2)102 (8.3)56 (5.5)96 (9.7)log rank Pvalue,HR (95% CI)p=.0018 0.609 (0.445, 0.833)p=.00040.554 (0.397, 0.773)Rate (%) at 2 years (95% CI)93.6(91.6, 95.1)88.5(85.7, 90.7)93.3(91.2, 95.0)87.384.4, 89.8)

Citation Format: Nadia Harbeck, Stephen Johnston, Peter Fasching, Miguel Martin, Masakazu Toi, Priya Rastogi, Chuangui Song, David Molthrop, Jacqueline Vuky, Toshinari Yamashita, Georgina Garnica Jaliffe, Mahmut Gumus, Desiree Headley, Ran Wei, Susana Barriga, Maria Munoz, Michael Method, Valerie Andre, Hans Kreipe, Joyce O'Shaughnessy. High Ki-67 as a biomarker for identifying patients with high risk early breast cancer treated in monarchE [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr PD2-01.

Long-Term Outcomes in KEYNOTE-052: Phase II Study Investigating First-Line Pembrolizumab in Cisplatin-Ineligible Patients With Locally Advanced or Metastatic Urothelial Cancer

PURPOSE

The phase II single-arm KEYNOTE-052 study evaluated the efficacy and safety of first-line pembrolizumab for patients with locally advanced or metastatic cisplatin-ineligible urothelial carcinoma (UC).

PATIENTS AND METHODS

Three hundred seventy patients received pembrolizumab 200 mg intravenously every 3 weeks for up to 24 months. Positive tumor programmed death ligand 1 (PD-L1) expression was defined as combined positive score (CPS) ≥ 10. Response was assessed by independent central review every 9 weeks per RECIST v1.1. The primary end point was objective response rate (ORR).

RESULTS

At data cutoff (September 26, 2018), the minimum follow-up was 2 years since the last patient enrolled. ORR was 28.6% (95% CI, 24.1% to 33.5%); 33 patients (8.9%) and 73 patients (19.7%) achieved complete and partial response, respectively. The median duration of response was 30.1 months (95% CI, 18.1 months to not reached [NR]); responses lasted ≥ 12 and ≥ 24 months in 67% and 52% of patients, respectively. Forty patients with complete or partial response completed 2 years of study treatment, and 32 had ongoing response at completion. Median overall survival (OS) was 11.3 months (95% CI, 9.7 to 13.1 months), and 12- and 24-month OS rates were 46.9% and 31.2%, respectively. In patients with CPS ≥ 10, ORR was 47.3% (95% CI, 37.7% to 57.0%) and median OS was 18.5 months (95% CI, 12.2 to 28.5 months). In patients with lymph node-only disease, ORR was 49.0% (95% CI, 34.8% to 63.4%), and median OS was 27.0 months (12.4 months to NR). There were no new safety signals.

CONCLUSION

First-line pembrolizumab confers meaningful and durable clinical response in cisplatin-ineligible patients with advanced UC and is associated with prolonged OS, particularly with PD-L1 CPS ≥ 10 and lymph node-only disease.

Feasibility of real-time serial comprehensive tumor analytics: Pilot study of olaparib and durvalumab in metastatic triple negative breast cancer (mTNBC)

e13092

Background: Longitudinal analysis of serial tumor biopsies is an under-utilized approach to studying adaptive mechanisms of resistance. We have established a comprehensive analytic platform to evaluate real-time trial sample analysis to inform precision oncology combinations in mTNBC. The primary endpoint of the study is feasibility of completing all CLIA assays within 28 days of biopsy. Methods: Following a pre-treatment biopsy and 4 weeks of olaparib monotherapy mTNBC patients underwent an on-treatment (tx) biopsy and durvalumab was added to their therapy. Pre- and on-tx biopsies underwent comparative analysis using CLIA assays (immunohistochemistry-IHC, whole exome seq, RNAseq and phospho-proteomics) as well as research assays (multiplex IHC-mIHC, cyclic immunofluorescence-IF, and reverse phase protein array-RPPA). Results: Serial biopsies were obtained from all 3 enrolled patients, and the primary endpoint was achieved for all patients (Table). Treatment was well tolerated, and 2 patients achieved clinical benefit > 6 months. In one patient with a prolonged CR ( > 18 months), the on-tx sample exhibited dramatic changes in protein network rewiring by protein data analysis (RPPA, cyclic-IF), and an increase in immune infiltrate by mIHC. Conclusions: This pilot confirmed the feasibility of rapid real-time analysis to inform treatment decisions. This led to the development and initiation of biomarker driven olaparib combination trials in mTNBC at our institution. Clinical trial information: NCT03544125 . [Table: see text]

Pembrolizumab as First-line Therapy in Cisplatin-ineligible Advanced Urothelial Cancer (KEYNOTE-052): Outcomes in Older Patients by Age and Performance Status

Background:

Patients with treatment-naive advanced urothelial cancer (UC) Ineligible for cisplatin-based chemotherapy are typically older and have comorbidities, representing a difficult-to-treat population.

Objective:

To evaluate the safety and antitumor activity of first-line pembrolizumab in subgroups of cisplatin-ineligible older patients (aged ≥65 and ≥75 yr) with advanced UC in KEYNOTE-052 (NCT02335424), including those with poor performance status (Eastern Cooperative Oncology Group performance status score 2 [ECOG PS2]).

Design, setting, and participants:

Patients were cisplatin ineligible, had treatment-naive, histologically/cytologically confirmed, locally advanced/metastatic UC with measurable disease (Response Evaluation Criteria in Solid Tumors version 1.1 [RECIST v1.1]), and had ECOG PS0–2. Patient subgroups analyzed were aged ≥65 yr (n = 302), ≥75 yr (n = 179), ≥65 yr with ECOG PS2 (≥65 yr + ECOG PS2; n = 119), and ≥75 yr + ECOG PS2 (n = 78).

Intervention:

All patients received pembrolizumab 200 mg intravenously every 3 wk until confirmed progression, intolerable toxicity, patient withdrawal, or 24 mo of therapy.

Outcome measurements and statistical analysis:

The primary endpoint was objective response rate (ORR) as per RECIST v1.1. The key secondary endpoints were overall survival (OS), duration of response (DOR), and safety.

Results and limitations:

ORRs for the ≥65 yr, ≥75 yr, ≥65 yr + ECOG PS2, and ≥75 yr + ECOG PS2 subgroups were 29%, 27%, 29%, and 31%, respectively; rates of complete and partial responses were similar across subgroups (9%, 5%, 6%, and 6%, and 20%, 22%, 23%, and 24%, respectively). Median DOR and OS were also consistent across the ≥65 yr and ≥65 yr + ECOG PS2 subgroups and the ≥75 yr and ≥75 yr + ECOG PS2 subgroups. Study limitations included open-label design, lack of a comparator group, and nature of post hoc exploratory analysis.

Conclusions:

The clinical benefit of pembrolizumab in advanced UC appeared to be consistent regardless of age and/or poor performance status.

This study looked at whether older age and poorer performance status affect how well patients with previously untreated advanced urothelial cancer ineligible for standard-of-care treatment respond to pembrolizumab. Outcomes with pembrolizumab were not affected by older age or poorer performance status, making it an effective option.

Phase II study of cabazitaxel (CAB) plus enzalutamide (ENZ) in metastatic castration-resistant prostate cancer (mCRPC)

86

Background: There are six agents that improve survival in mCRPC, each administered as a single agent. Combinations of agents with distinct mechanisms of action have the potential to improve outcomes. Methods: We performed a multi-institution phase I/II study to examine safety and efficacy of CAB plus ENZ with mandatory granulocyte-colony stimulating factor support in mCRPC. Results: A sample size of 3 to 12 subjects for the phase I portion and 33 for the phase II portion provided 82% power to detect PSA response rate (decrease ≥90%) of 50% compared to the null hypothesis of 24%. The main eligibility criteria allowed prior abiraterone/prednisone (AAP) and docetaxel (in the metastatic hormone sensitive setting). Baseline characteristics: median age 69 years (47 - 82), median PSA 20.2 ng/dl (0.2 - 966.3); 7 subjects had visceral disease, 10 received prior AAP, and 8 received prior docetaxel. In the phase I portion, there were no dose limiting toxicities using CAB 25 mg/m2 IV Q3wks up to 10 cycles and ENZ 160 mg PO QD, hence this dosing was used for the phase II portion. 33 men with mCRPC were treated with CAB plus ENZ in the phase II arm. PSA response rates are listed in Table. Prior exposure to AAP decreased PSA response, but subjects who had prior AAP also had higher pre-treatment PSA. There were no treatment related deaths. Dose reduction of CAB to 20 mg/m2 was needed in 7 subjects. Over the course of the study, 14 Grade 3 adverse events occurred that were deemed possibly related to treatment: fatigue (n=2, 6%), febrile neutropenia (n=2, 6%), leukopenia (n=2, 6%), thrombocytopenia (n=2, 6%), anemia (n=1, 3%), hypertension (n=1, 3%), leukocytosis (n=2, 6%), fracture (n=1, 3%), failure to thrive (n=1, 3%). Conclusions: CAB plus ENZ was tolerable and associated with promising anti-tumor activity, particularly in abiraterone-naïve subjects. Further evaluation of this regimen is warranted. This project was managed by the Prostate Cancer Clinical Trials Consortium and funded by Astellas Inc. and Sanofi. Clinical trial information: NCT02522715. [Table: see text]

KEYNOTE-052: Phase 2 study evaluating first-line pembrolizumab (pembro) in cisplatin-ineligible advanced urothelial cancer (UC)— Updated response and survival results

4546

Background: Initial results of the phase 2 KEYNOTE-052 (NCT02335424) study led to approval of pembro for cisplatin-ineligible patients (pts) with advanced UC. Updated results representing follow-up of over 2 y since last pt enrolled are presented. Methods: Pts had confirmed advanced UC, were cisplatin-ineligible (ECOG PS 2, CrCl ≥30 to ˂60 mL/min, grade ≥2 neuropathy/hearing loss, NYHA Class III heart failure), and received no prior chemotherapy for metastatic disease. Pts received pembro 200 mg IV Q3W until progression, unacceptable toxicity, withdrawal, or 24 mo of therapy, whichever occurred first. Primary end point was confirmed ORR (RECIST v1.1, independent central review). Key secondary end points: duration of response (DOR), overall survival (OS), and safety. Data cutoff was September 26, 2018. Results: Among pts assessed (N = 370), median age was 74 y, 85% had visceral disease, and 30% were PD-L1 positive (combined positive score [CPS] ≥10). Median follow-up was 11.4 mo (range, 0.1-41.2) for all pts and 29.3 mo (range 7-41.2) for responders. Confirmed ORR was 29% (95% CI, 24-34): complete response, 9% (n = 33); partial response, 20% (n = 73). Median DOR was 30.1 mo (95% CI, 18.1-not reached [NR]); 67% and 52% of pts had DOR ≥12 and ≥24 mo, respectively. Median OS was 11.3 mo (range 9.7-13.1); 12- and 24-mo OS rates were 47% and 31%, respectively. In pts with CPS ˂10 (n = 251) and ≥10 (n = 110), respectively, confirmed ORR was 20% (95%CI, 16-26) and 47% (95% CI, 38-57). Median DOR for pts with CPS < 10 and ≥10 was 18.2 mo (95% CI, 9.7-NR) and NR (95% CI, 18.1-NR); DOR ≥24 mo was 45% and 57%, respectively. Median OS for pts with CPS < 10 and ≥10 was 9.7 mo (95% CI, 7.6-11.5) and 18.5 mo (95% CI, 12.2-28.5); 24-mo OS rates were 24% and 47% respectively. Treatment-related adverse events (AEs) occurred in 67% of pts. Most common were fatigue and pruritus (18% each); 21% were grade ≥3, including 1 death (myositis). Conclusions: With extended follow-up, pembro continued to elicit clinically meaningful, durable antitumor activity in cisplatin-ineligible pts with advanced UC and was more pronounced in those with PD-L1 expression CPS ≥10. Pembro safety profile was as expected. Clinical trial information: NCT02335424.

A phase II trial of olaparib and durvalumab in metastatic BRCA wild type triple-negative breast cancer

TPS1111

Background: There is an urgent need to develop novel non chemotherapy treatments for metastatic triple negative breast cancer (mTNBC) patients who otherwise have a poor prognosis. Immune checkpoint blockade (ICB) and PARP inhibitors (PARPi) have independently shown promise for the treatment of mTNBC, and the combination has shown early benefit in the MEDIOLA and TOPACIO trials. This trial looks to 1) evaluate the efficacy of the combination of the PARPi olaparib and the PD-L1 inhibitor durvalumab, and 2) perform extensive multi-omics including protein based image analytics (multiplex IHC, cyclic immunofluorescence) on serial biopsies to identify predictive biomarkers and resistance mechanisms. Methods: Trial Design: This is a single-arm phase II study to assess the efficacy of the combination of olaparib and durvalumab in BRCA-wildtype mTNBC. mTNBC participants will undergo a pre-treatment biopsy, then will start a 4 week induction treatment with olaparib (300 mg PO BID). At the end of 4 weeks of single agent therapy, participants will undergo a repeat on-treatment biopsy, following which durvalumab (1500 mg IV every 4 weeks) will be added to olaparib. Participants will also be offered an optional biopsy on progression. Endpoints: The primary endpoint of this study is overall response rate (ORR) to olaparib and durvalumab therapy. Secondary efficacy endpoints include clinical benefit rate, duration of response, progression-free, and overall survival. The incidence and severity of on-treatment adverse events will be collected per CTCAE 5.0. Statistical Methods: 28 participants are planned for enrollment to this study. A 2-stage analysis will be performed using a Simon 2-stage Minimax design. The null (ICB alone) and alternative (ICB + PARPi) hypotheses are: H0: π = 0.15 and Ha: π = 0.35. For the primary endpoint, a total sample size of 28 participants will achieve 80% power to detect the ORR difference of 0.20 with one-sided type I error =0.05. The trial will be terminated in stage I if 2 or less out of the first 15 participants respond. If the trial goes on to the stage II, a total of 28 participants will be studied. If the total number responding is less than or equal to 7, the combination is rejected. Current Enrollment: The study was activated on 1/7/2019. To date, 3 out of 15 patients have been accrued to stage I of the study Clinical trial information: NCT03801369.

Abstract P2-09-03: Updated efficacy of first or second-line pembrolizumab (pembro) plus capecitabine (cape) in metastatic triple negative breast cancer (mTNBC) and correlations with baseline lymphocyte and naïve CD4+ T-cell count

Background: In mTNBC, anti-PD-1/L1 monotherapy is most effective when administered early in the course of disease, with recent trials demonstrating overall response rates (ORR) of 23-26% in the first-line setting and 5-6% in later lines. This may reflect iatrogenic lymphopenia from preceding cytotoxic chemotherapy. Furthermore, curative-intent chemotherapy is associated with prolonged suppression of naïve CD4+ cells, a T-cell subset that may play a critical role in the generation of de novo anti-tumor immune responses. We present the final clinical results of a pilot study evaluating the safety and efficacy of combining pembrolizumab plus standard-of-care capecitabine in the first/second-line mTNBC setting. We also explore potential associations between clinical benefit and lymphopenia, preceding chemotherapy, and absolute naïve CD4+ counts.

Methods: In a pilot study, we evaluated the tolerability and preliminary efficacy of concurrent pembro (200mg IV q21 day) plus investigator-selected 1st/2nd line paclitaxel (80mg/m2 IV weekly) or oral cape (2,000mg BID, weekly 1 on/1 off). The primary endpoint was tolerability, defined as the proportion of subjects receiving &gt;6 weeks concurrent therapy without dose discontinuation with toxicities reported per CTCAE v4.0. The secondary endpoint was 12-week objective response rate (ORR) by RECIST1.1. Exploratory endpoints included peripheral blood cell enumeration by real-time flow cytometry and routine clinical laboratory. Naïve CD4+ cells were defined as CD45+ CD3+ TCRab+ CD4+ CD45RA+ CCR7+. Here, we report the results of the pilot phase of the cape cohort (NCT02734290).

Results: Twelve of 14 subjects were treated in the first-line setting. All subjects (14/14, 100%) tolerated cape+pembro for &gt;6 weeks, with toxicities consistent with monotherapy cape experience (diarrhea: grade I-II 50%, grade III 7%; hand-foot: grade I-II 71%) that improved with dose-reduction as needed. At 12 weeks, the ORR was 6/14 (42.9%), and the clinical benefit rate (ORR + stable disease) was 8/14 (57.1%). Depressed absolute lymphocyte count at baseline (ALC&lt;1.0/uL: 33% CBR; ALC≥1.0/uL: 75% CBR) and recent exposure to cytotoxic chemotherapy (&lt;6 months: 33% CBR; &gt;6 months: 75% CBR) were associated with reduced clinical benefit. By flow cytometry, subjects experiencing clinical benefit had higher baseline absolute naïve CD4+ counts (average 283 cells/uL v. 93 cells/uL, p=.069).

Conclusions: This study met the primary endpoint of safety for cape plus pembro in mTNBC, with encouraging clinical activity. These data are supportive of further studies evaluating combination chemotherapy plus anti-PD-1/L1 mTNBC. We observed greater clinical benefit in subjects with non-suppressed ALC, less exposure to recent chemo, and higher baseline naïve CD4+ counts, suggesting that iatrogenic immunosuppression can impair response to immune checkpoint therapy in mTNBC. These findings should be confirmed in ongoing randomized trials of immune checkpoint +/- chemotherapy in mTNBC, and should be considered in the design of future clinical trials.

Citation Format: Page DB, Pucilowska J, Bennetts L, Kim I, Sanchez K, Martel M, Conlin A, Moxon N, Mellinger S, Acheson A, Kemmer K, Mitri Z, Vuky J, Ahn J, Abaya C, Manigault T, Basho R, Urba WJ, McArthur HL. Updated efficacy of first or second-line pembrolizumab (pembro) plus capecitabine (cape) in metastatic triple negative breast cancer (mTNBC) and correlations with baseline lymphocyte and naïve CD4+ T-cell count [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P2-09-03.

Abstract CT069: Baseline gene expression patterns of CDK4/6 inhibitor-naïve or -refractory HR+, HER2- advanced breast cancer in the phase Ib study of ribociclib plus everolimus plus exemestane

Background: Preclinical data suggest that combination of endocrine therapy (ET) with a cyclin-dependent kinase 4/6 inhibitor (CDK4/6i) and mammalian target of rapamycin inhibitor (mTORi) may overcome prior treatment resistance in hormone receptor-positive (HR+), human epidermal growth factor receptor 2-negative (HER2-) advanced breast cancer (ABC). The Phase Ib CLEE011X2106 study (NCT01857193) is investigating ribociclib (RIB; CDK4/6i) + everolimus (EVE; mTORi) + exemestane (EXE; ET) in patients with HR+, HER2- ABC resistant to letrozole or anastrozole. The objective of this analysis is to characterize baseline gene expression patterns in the CDK4/6i-naïve and -refractory groups, and assess the potential correlation with clinical activities.

Methods: Postmenopausal women with HR+, HER2- ABC resistant to letrozole or anastrozole, and who had received no prior CDK4/6i or whose disease had progressed on or within 1 month of CDK4/6i therapy, were enrolled in the CDK4/6i-naïve and -refractory dose expansion groups, respectively. More than 1 line of chemotherapy for ABC or prior treatment with EXE or an mTORi was not permitted. Patients received RIB (300 mg, 3-weeks on/1-week off) + EVE (2.5 mg, continuous) + EXE (25 mg, continuous) until disease progression or study discontinuation. Baseline tumor samples (collected after CDK4/6i therapy in the CDK4/6i-refractory group) were assessed for mRNA expression using the NanoString 230-gene nCounter® GX Human Cancer Reference panel.

Results: As of May 15, 2017, the 24-week clinical benefit rate was 56% (9/16) in the CDK4/6i-naïve group and 24% (4/17) in the -refractory group. Baseline tumor mRNA expression was evaluable in 14 patients: CDK4/6i naïve, n=8 (best response: 7 stable disease [SD], 1 progressive disease [PD]); CDK4/6i refractory, n=6 (2 SD, 4 PD). Across all patients (both groups), those with SD tended to have higher ESR1 expression compared with those experiencing PD, with a trend for higher baseline ESR1 expression in the CDK4/6i-naïve group compared with the -refractory group. Also across all patients, higher overall baseline expression of cell cycle control genes and mitogen-activated protein kinase (MAPK) pathway genes appeared to trend with PD. Additionally, in the CDK4/6i-refractory group, there was a trend for higher CDK2 and/or CCNE1 expression in patients with PD compared with SD. A heat map of 24 genes indicated differences in gene expression patterns between the CDK4/6i-naïve and -refractory groups.

Conclusions: Gene expression patterns differ between CDK4/6i-naïve and -refractory tumors. Higher expression of cell cycle control genes (particularly CDK2 and CCNE1) and MAPK pathway genes appears to trend with resistance to the RIB + EVE + EXE combination after progression on prior CDK4/6i. Due to the small number of samples, further investigation is needed.

Citation Format: Aditya Bardia, Shanu Modi, Javier Cortes, Mario Campone, Luc Dirix, Brigette Ma, J Thaddeus Beck, Jorge Chaves, Amy Weise, Jacqueline Vuky, Gilberto Lopes, Miguel Gil-Gil, Xiaochun Liu, Wei He, Faye Su, Michelle Miller, Mariana Chavez-MacGregor. Baseline gene expression patterns of CDK4/6 inhibitor-naïve or -refractory HR+, HER2- advanced breast cancer in the phase Ib study of ribociclib plus everolimus plus exemestane [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr CT069.

First-line pembrolizumab in cisplatin-ineligible patients with locally advanced and unresectable or metastatic urothelial cancer (KEYNOTE-052): a multicentre, single-arm, phase 2 study

BACKGROUND

More than half of all patients with advanced urothelial cancer cannot receive standard, first-line cisplatin-based chemotherapy because of renal dysfunction, poor performance status, or other comorbidities. We assessed the activity and safety of first-line pembrolizumab in cisplatin-ineligible patients with locally advanced and unresectable or metastatic urothelial cancer.

METHODS

In this multicentre, single-arm, phase 2 study (KEYNOTE-052), cisplatin-ineligible patients with advanced urothelial cancer who had not been previously treated with systemic chemotherapy were recruited from 91 academic medical centres in 20 countries. Enrolled patients received intravenous pembrolizumab 200 mg every 3 weeks. The primary endpoint was objective response (the proportion of patients who achieved complete or partial response) in all patients and by PD-L1 expression status according to the Response Evaluation Criteria in Solid Tumors, version 1.1, as assessed by independent central review. PD-L1 expression was assessed in tumour and inflammatory cells from tumour biopsies provided at study entry. Activity and safety were analysed in all patients who received at least one dose of pembrolizumab (all-patients-treated population). This study is registered with ClinicalTrials.gov, number NCT02335424, and follow-up is ongoing.

FINDINGS

Between Feb 24, 2015, and Aug 8, 2016, 374 patients were enrolled and 370 patients received at least one dose of pembrolizumab. 89 (24%, 95% CI 20-29) of 370 patients had a centrally assessed objective response, and as of Sept 1, 2016 (data cutoff), 74 (83%) of 89 responses were ongoing. Median follow-up was 5 months (IQR 3·0-8·6). A PD-L1-expression cutoff of 10% was associated with a higher frequency of response to pembrolizumab; 42 (38%, 95% CI 29-48) of 110 patients with a combined positive score of 10% or more had a centrally assessed objective response. The most common grade 3 or 4 treatment-related adverse events were fatigue (eight [2%] of 370 patients), alkaline phosphatase increase (five [1%]), colitis, and muscle weakness (both four [1%]). 36 (10%) of 370 patients had a serious treatment-related adverse event. 17 (5%) of 370 patients died from non-treatment-related adverse events associated with death, and one patient died from treatment-related adverse events (myositis in addition to grade 3 thyroiditis, grade 3 hepatitis, grade 3 pneumonia, and grade 4 myocarditis).

INTERPRETATION

First-line pembrolizumab has antitumour activity and acceptable tolerability in cisplatin-ineligible patients with urothelial cancer, most of whom were elderly, had poor prognostic factors, or had serious comorbidities. In view of this result, pembrolizumab has become a new treatment option for patients who are cisplatin-ineligible or not suitable candidates for chemotherapy. Pembrolizumab in the first-line setting is being further assessed in the phase 3 KEYNOTE-361 trial (ClinicalTrials.gov, NCT02335424).

FUNDING

Merck & Co.

Biomarker findings and mature clinical results from KEYNOTE-052: First-line pembrolizumab (pembro) in cisplatin-ineligible advanced urothelial cancer (UC)

4502

Background: Comorbidities and renal impairment preclude many with advanced UC from receiving chemotherapy. Initial results from the phase 2 KEYNOTE-052 (NCT02335424) trial suggested first-line pembro is active and safe in cisplatin-ineligible advanced UC. We present updated efficacy and safety data (all pts have ≥6 mo follow-up) and evaluate biomarkers correlated with outcomes. Methods: Eligibility criteria included cisplatin-ineligible (ECOG PS 2, CrCl ≥30- < 60 mL/min, grade ≥2 neuropathy/hearing loss, NYHA Class 3 heart failure), advanced UC, and no prior systemic chemotherapy. Pts received pembro 200 mg IV Q3W. Imaging was performed at wk 9, then Q6W for the first year, and Q12W thereafter. Primary end point was confirmed ORR (RECIST v1.1, independent review). Efficacy and safety were assessed in the 370 pts with ≥1 pembro dose. The associations of an 18-gene expression profile (GEP) and IHC PD-L1 combined positive score (CPS) with ORR were evaluated. Results: As of the Dec 19, 2016, data cutoff, ORR was 29% (95% CI, 24-34): 25 (7%) and 81 (22%) pts achieved complete and partial responses. Another 69 pts (19%) had stable disease as best response, for a clinical benefit rate of 47%. Median time to response was 2 mo (range, 1-5). At a median follow-up of 8 mo (range, 0.1-20) across all pts, median duration of response was not reached (range, 1+-18+ mo). 74% of responses were ongoing. Any-grade and grade ≥3 drug-related AEs occurred in 239 (65%) and 68 (18%) pts. Immune-mediated AEs occurred in 76 (21%) pts. Evidence supporting a positive association with response was seen in the first 100 pts for both biomarkers (GEP, n = 72, P = 0.007, ROC AUC 0.69; CPS, n = 96, P= 0.111, ROC AUC 0.58); biomarker data for all pts will be presented. ORR in the 110 pts with CPS ≥10% was 47% (95% CI, 38-57). Conclusions: Results confirm that pembro elicits clinically meaningful, durable responses in cisplatin-ineligible advanced UC. Consistent with PD-1 pathway biology, biomarkers (GEP and CPS) showed the expected trends of positive association with response to pembro. Pembro was well tolerated across cisplatin-ineligible pts, including elderly and pts with poor performance status. Clinical trial information: NCT02335424.

Pembrolizumab as first-line therapy in cisplatin-ineligible advanced urothelial cancer: Results from the total KEYNOTE-052 study population

284

Background: Treatment options are limited for patients (pts) with advanced urothelial cancer (UC) ineligible to receive cisplatin-based chemotherapy. Interim results from the first 100 pts enrolled in the phase 2, open-label KEYNOTE-052 (ClinicalTrials.gov, NCT02335424) study suggested first-line pembrolizumab (pembro) had antitumor activity and acceptable safety in this pt population. Results from the fully enrolled study are presented. Methods: Key eligibility criteria included age ≥ 18 y, advanced UC of the renal pelvis, ureter, bladder, or urethra, cisplatin ineligibility (ECOG PS 2, creatinine clearance ≥ 30 to < 60 mL/min, grade ≥ 2 neuropathy or hearing loss, NYHA Class 3 heart failure), no prior systemic chemotherapy for advanced UC, measurable disease per RECIST v1.1, ECOG PS 0-2, and provision of a tumor sample for biomarker analyses. Pembro 200 mg was administered every 3 wk. Imaging was performed at wk 9, then every 6 wk for the first year, and every 12 wk thereafter. The primary end point was confirmed overall response rate (ORR; RECIST v1.1, independent review). Efficacy data are presented for pts with ≥ 4 mo follow-up, and safety data are presented for all pts. Results: In total, 370 pts were enrolled; median age was 74 y (range, 34-94 y); 42% had an ECOG PS 2. Reasons for cisplatin ineligibility included ECOG PS 2 (32%), renal dysfunction (49%), and both ECOG PS 2 and renal dysfunction (10%). ORR (95% CI) was 27% (22%-32%) among pts with ≥ 4 mo follow-up (n = 307); 6% of pts achieved a complete response. Among the ≥ 4 mo follow-up group, median (range) time to response was 2.0 (1.6-4.8) mo; median (range) duration of response was not reached (1+ to 14+ mo). 78% of responders had a response for ≥ 6 mo (KM estimate). PFS and OS rates at 6 mo were 31% and 67%, respectively (KM estimate). Any grade and grade ≥ 3 drug-related AEs occurred in 229 (62%) and 58 (16%) pts. 19 (5%) pts discontinued treatment because of a drug-related AE. Conclusions: Results from the fully enrolled KEYNOTE-052 study confirm that pembro elicits clinically meaningful and durable responses in cisplatin-ineligible pts with UC, including elderly pts and those with poor performance status. Clinical trial information: NCT02335424.

A Phase 1/2 Trial of a Combination of Paclitaxel and Trastuzumab With Daily Irradiation or Paclitaxel Alone With Daily Irradiation After Transurethral Surgery for Noncystectomy Candidates With Muscle-Invasive Bladder Cancer (Trial NRG Oncology RTOG 0524)

PURPOSE

Bladder preservation therapy is an effective treatment for muscle-invasive urothelial carcinoma (UC). In this study we treated noncystectomy candidates with daily radiation and weekly paclitaxel for 7 weeks. Patients whose tumors showed her2/neu overexpression were additionally treated with weekly trastuzumab.

METHODS AND MATERIALS

Sixty-eight evaluable patients were treated with radiation therapy and either paclitaxel + trastuzumab (group 1) or paclitaxel alone (group 2). Groups were assigned on the basis of her2/neu immunohistochemistry results. Patients received 1.8-Gy fractions to a total dose of 64.8 Gy. The primary endpoint of the study was treatment-related toxicity, and secondary endpoints included complete response (CR) rate, protocol completion rate, and survival.

RESULTS

A total of 20 evaluable patients were treated in group 1 and 46 patients in group 2. Acute treatment-related adverse events (AEs) were observed in 7 of 20 patients in group 1 (35%) and 14 of 46 patients in group 2 (30.4%). Protocol therapy was completed by 60% (group 1) and 74% (group 2) of patients. Most incompletions were due to toxicity, and the majority of AEs were gastrointestinal, including 1 grade 5 AE (group 1). Two other deaths (both in group 2) were unrelated to protocol therapy. No unexpected cardiac, hematologic, or other toxicities were observed. The CR rate at 1 year was 72% for group 1 and 68% for group 2.

CONCLUSIONS

In patients with muscle-invasive UC who are not candidates for cystectomy, daily radiation combined with paclitaxel is an effective treatment strategy with a high completion rate and moderate toxicity. In patients with her2/neu-positive tumors, a group generally considered to have worse outcomes, the addition of trastuzumab appears to result in comparable efficacy and toxicity. Further biomarker-driven trials should be undertaken in advancing treatment of this challenging disease.

The initial report of RTOG 0524: Phase I/II trial of a combination of paclitaxel and trastuzumab with daily irradiation or paclitaxel alone with daily irradiation following transurethral surgery for noncystectomy candidates with muscle-invasive bladder cancer

LBA287

Background: Most patients (pts) with muscle-invasive bladder urothelial carcinoma (UC) undergo definitive local treatment with radical cystectomy. Up to 50% of pts with UC overexpress HER2/neu, which may be associated with reduced responsiveness to chemoradiation and reduced survival. Many pts with UC have comorbidities that preclude surgery, creating a traditionally underserved population with worse outcomes. RTOG 0524 evaluated the safety and efficacy of trimodality, organ-preserving therapy in pts not suitable for cystectomy. Methods: Pts with invasive bladder UC (stages T2-T4a, N0-1, M0) underwent cystoscopic tumor resection. Tumors were analyzed by HER2/neu immunohistochemistry (IHC) and assigned to chemotherapy group I (IHC 2+ or 3+; paclitaxel and trastuzumab) or II (IHC negative or 1+; paclitaxel alone). Concurrent weekly paclitaxel (50 mg/m2), weekly trastuzumab (group I only) and daily radiation (64.8 Gy total in 36 fractions) were given for seven consecutive weeks. Results: 21 eligible patients were entered in group I and 47 in group 2, with median ages of 80 and 73, respectively. The primary endpoint was acute protocol-defined toxicity related to treatment. Acute toxicity was observed in 7/21 pts (33%) in group I and 14/47 pts (30%) in group II. Most common grade > 3 adverse events in groups I and II were marrow suppression (43% and 17%), diarrhea (33% and 30%), and hyponatremia (14% and 4%). Three deaths on study were attributed to colonic perforation, pneumonia, and sudden death. Radiation completion rates were 72% and 85% in the two groups, and full-dose chemotherapy completion rates were 52% and 51%. Evaluation by cystoscopy and/or tumor biopsy at 12 weeks noted complete response in 9/13 pts (69%) in group I, in 19/33 pts (58%) in group II, and was not performed in the remaining pts. Conclusions: Trimodality bladder-preserving therapy is an appropriate treatment in noncystectomy candidates with invasive UC. The response rate for HER2/neu-targeted therapy is encouraging but may increase certain adverse events in this challenging population. Clinical trial information: NCT00238420.

Randomized trial to assess the impact of venlafaxine and soy protein on hot flashes and quality of life in men with prostate cancer

PURPOSE

Hot flashes occur in approximately 80% of androgen-deprived men. Few intervention studies have been conducted to relieve hot flashes in men.

PATIENTS AND METHODS

Eligible androgen-deprived men were randomly assigned to one of four daily regimens (2 × 2 factorial design) for 12 weeks: milk protein powder and placebo pill, venlafaxine and milk protein powder, soy protein powder and placebo pill, or venlafaxine and soy protein powder. The primary end point was hot flash symptom severity score (HFSSS), defined as number of hot flashes times severity. The secondary end point was quality of life (QoL), assessed by using the Functional Assessment of Cancer Therapy-Prostate.

RESULTS

In all, 120 men age 46 to 91 years participated. Most were white (78%) and overweight or obese (83%). Toxicity was minimal. Neither venlafaxine nor soy protein alone or in combination had a significant effect on HFSSS. Soy protein, but not venlafaxine, improved measures of QoL.

CONCLUSION

In androgen-deprived men, neither venlafaxine nor soy proved effective in reducing hot flashes. Interventions that appear effective for decreasing hot flashes in women may not always turn out to be effective in men.

Phase II trial of neoadjuvant docetaxel and CG1940/CG8711 followed by radical prostatectomy in patients with high-risk clinically localized prostate cancer

BACKGROUND

Prostate cancer (PC) is the most commonly diagnosed noncutaneous malignancy in American men. PC, which exhibits a slow growth rate and multiple potential target epitopes, is an ideal candidate for immunotherapy. GVAX for prostate cancer is a cellular immunotherapy, composed of PC-3 cells (CG1940) and LNCaP cells (CG8711). Each of the components is a prostate adenocarcinoma cell line that has been genetically modified to secrete granulocyte-macrophage colony-stimulating factor. Hypothesizing that GVAX for prostate cancer could be effective in a neoadjuvant setting in patients with locally advanced disease, we initiated a phase II trial of neoadjuvant docetaxel and GVAX. For the trial, the clinical effects of GVAX were assessed in patients undergoing radical prostatectomy (RP).

METHODS

Patients received docetaxel administered at a dose of 75 mg/m(2) every 3 weeks for 4 cycles. GVAX was administered 2-3 days after chemotherapy preoperatively for four courses of immunotherapy. The first dose of GVAX was a prime immunotherapy of 5×10(8) cells. The subsequent boost immunotherapies consisted of 3×10(8) cells. After RP, patients received an additional six courses of immunotherapy. Pathologic complete response, toxicity, and clinical response were assessed. The primary endpoint of the trial was a pathologic state of pT0, which is defined as no evidence of cancer in the prostate.

RESULTS

Six patients completed neoadjuvant docetaxel and GVAX therapy. No serious drug-related adverse events were observed. Median change in prostate-specific antigen (PSA) following neoadjuvant therapy was 1.47 ng/ml. One patient did not undergo RP due to the discovery of positive lymph nodes during exploration. Of the five patients completing RP, four had a downstaging of their Gleason score. Undetectable PSA was achieved in three patients at 2 months after RP and in two patients at 3 years after RP.

CONCLUSIONS

Neoadjuvant docetaxel/GVAX is safe and well tolerated in patients with high-risk locally advanced PC. No evidence of increased intraoperative hemorrhage or increased length of hospital stay postoperatively was noted. These results justify further study of neoadjuvant immunotherapy.

Phase II study to assess the efficacy, safety and tolerability of the mitotic spindle kinesin inhibitor AZD4877 in patients with recurrent advanced urothelial cancer

BACKGROUND

AZD4877 is a potent inhibitor of the mitotic spindle kinesin, Eg5. Early-phase clinical studies in a broad range of cancers showed that AZD4877 is well tolerated. This Phase II study evaluated the efficacy, safety and pharmacokinetics (Cmax) of AZD4877 in patients with previously treated advanced urothelial cancer (ClinicalTrials.gov identifier NCT00661609).

PATIENTS AND METHODS

AZD4877 25 mg was administered once-weekly for 3 weeks of each 4-week cycle until disease progression, death, unacceptable toxicity or withdrawal. The primary objective was to determine the objective response rate (RECIST). Recruitment was to be halted if ≤ 2 of the first 20 evaluable patients achieved an objective tumor response. Cmax was assessed on days 1 and 8 of cycle 1.

RESULTS

None of the first 20 patients evaluable for efficacy achieved an objective response; enrollment was therefore halted. During this initial analysis, a further 21 patients were recruited. Overall, 39 patients were evaluable for efficacy, including one with confirmed partial response (PR) and seven patients with stable disease for ≥ 8 weeks (including one unconfirmed PR). The most commonly reported treatment-related adverse events (TRAEs) were neutropenia (22 patients), fatigue (12), leukopenia (7) and constipation (6); the most commonly reported grade ≥ 3 TRAE was neutropenia (21). Four patients had serious TRAEs. On days 1 and 8, the geometric mean Cmax of AZD4877 was 138 ng/ml (CV = 75 %) and 144 ng/ml (CV = 109 %), respectively.

CONCLUSIONS

AZD4877 was generally tolerable in patients with advanced urothelial cancer. Given the limited clinical efficacy, further development of AZD4877 in urothelial cancer is not planned.

The evaluation of flaxseed for hot flashes: Results of a randomized, controlled trial, NCCTG study N08C7

CRA9015

Background: Hot flashes are a common symptom during the menopause transition or following breast cancer treatment that can negatively impact the quality of life for many women. Preliminary data have suggested that flaxseed, a rich source of dietary lignans, may be a potentially effective treatment for hot flashes. Methods: A phase III randomized, placebo controlled trial was conducted to evaluate the efficacy of flaxseed in reducing hot flashes. Postmenopausal women were randomly assigned to a flaxseed bar (providing 410 mg of lignans) for 6 weeks vs a placebo bar. Participants completed daily prospective, self report hot flash diaries during the baseline week and then began eating one study bar per day for 6 weeks, while continuing to record their daily hot flashes. The intra-patient difference in hot flash activity between baseline and the last treatment week was the primary endpoint. Side effects of the bars were evaluated through self report and CTC assessment. Results: Between October and December 2009, 188 women were enrolled onto this trial. Mean hot flash scores were reduced by 4.9 units in the flaxseed group and 3.5 in the placebo group (p=0.29). In both groups, a little over a third of the women received a 50% reduction in their hot flash scores. Only one side effect was significantly different between groups, that being grade 1 pruritis, which was more common (7%) in the placebo group versus 1% in the flaxseed group. Both groups reported increased abdominal distension, flatulence, diarrhea and nausea. Adherence and ability to detect treatment assignment did not differ between groups. Conclusions: The results of this trial do not support the use of 410 mg of flaxseed lignans for the reduction of hot flashes. The gastrointestinal side effects seen in both groups were likely due to the fiber content in the flaxseed and placebo bars.

A phase II study of everolimus in combination with imatinib for previously treated advanced renal carcinoma

PURPOSE

This phase II study evaluated the activity of combined treatment with the mTOR inhibitor everolimus and the PDGFR inhibitor imatinib in patients with previously-treated, advanced renal carcinoma. The primary endpoint was estimation of the 3-month progression-free rate.

PATIENTS AND METHODS

Eligible patients had metastatic or unresectable clear cell renal carcinoma, at least one prior systemic therapy, no prior mTOR inhibitor therapy, performance status 0-2, and measurable disease. Treatment consisted of everolimus 2.5 mg p.o. daily and imatinib 600 mg p.o. daily. The primary endpoint was the 3-month progression-free rate.

RESULTS

The study was closed after the first 19 patients because of an insufficient number of patients who were progression-free at 3 months. The 3-month progression-free rate was 49% (95% C.I. 23%, 72%) and the median progression-free survival was 2.9 months (95% C.I. 1.9, 6.2). Toxicities with an incidence of >  50% included nausea, elevated serum creatinine, edema, anemia, hypocalcemia, fatigue, diarrhea, vomiting, and dyspnea, and leukopenia.

CONCLUSION

The combination of everolimus with imatinib in previously treated patients with advanced renal carcinoma did not result in a sufficient 3-month progression-free rate to warrant further investigation of this combination.