Talazoparib in Patients with Advanced Breast Cancer and a Germline BRCA Mutation.

BACKGROUND: The poly(adenosine diphosphate-ribose) inhibitor talazoparib has shown antitumor activity in patients with advanced breast cancer and germline mutations in BRCA1 and BRCA2 ( BRCA1/2). METHODS: We conducted a randomized, open-label, phase 3 trial in which patients with advanced breast cancer and a germline BRCA1/2 mutation were assigned, in a 2:1 ratio, to receive talazoparib (1 mg once daily) or standard single-agent therapy of the physician's choice (capecitabine, eribulin, gemcitabine, or vinorelbine in continuous 21-day cycles). The primary end point was progression-free survival, which was assessed by blinded independent central review. RESULTS: Of the 431 patients who underwent randomization, 287 were assigned to receive talazoparib and 144 were assigned to receive standard therapy. Median progression-free survival was significantly longer in the talazoparib group than in the standard-therapy group (8.6 months vs. 5.6 months; hazard ratio for disease progression or death, 0.54; 95% confidence interval [CI], 0.41 to 0.71; P<0.001). The interim median hazard ratio for death was 0.76 (95% CI, 0.55 to 1.06; P=0.11 [57% of projected events]). The objective response rate was higher in the talazoparib group than in the standard-therapy group (62.6% vs. 27.2%; odds ratio, 5.0; 95% CI, 2.9 to 8.8; P<0.001). Hematologic grade 3-4 adverse events (primarily anemia) occurred in 55% of the patients who received talazoparib and in 38% of the patients who received standard therapy; nonhematologic grade 3 adverse events occurred in 32% and 38% of the patients, respectively. Patient-reported outcomes favored talazoparib; significant overall improvements and significant delays in the time to clinically meaningful deterioration according to both the global health status-quality-of-life and breast symptoms scales were observed. CONCLUSIONS: Among patients with advanced breast cancer and a germline BRCA1/2 mutation, single-agent talazoparib provided a significant benefit over standard chemotherapy with respect to progression-free survival. Patient-reported outcomes were superior with talazoparib. (Funded by Medivation [Pfizer]; EMBRACA ClinicalTrials.gov number, NCT01945775 .).

ATTAIN: Phase III study of etirinotecan pegol versus treatment of physician's choice in patients with metastatic breast cancer and brain metastases.

The increasing incidence of breast cancer brain metastases is a major clinical problem with its associated poor prognosis and limited treatment options. The long-acting topoisomerase-1 inhibitor, etirinotecan pegol, was designed to preferentially accumulate in tumor tissue including brain metastases, providing sustained cytotoxic SN38 levels. Motivated by improved survival findings from subgroup analyses from the Phase III BEACON trial, this ongoing randomized, Phase III trial compares etirinotecan pegol to drugs commonly used for advanced breast cancer in patients with stable, treated breast cancer brain metastases who have been previously treated with an anthracycline, taxane and capecitabine. The primary end point is overall survival. Secondary end points include objective response rate, progression-free survival and time to CNS disease progression or recurrence in patients with/without CNS lesions present at study entry. Trial registration number: NCT02915744.

Phase 3 trial of defibrotide for the treatment of severe veno-occlusive disease and multi-organ failure.

Hepatic veno-occlusive disease (VOD), also called sinusoidal obstruction syndrome (SOS), is a potentially life-threatening complication of hematopoietic stem cell transplantation (HSCT). Untreated hepatic VOD/SOS with multi-organ failure (MOF) is associated with >80% mortality. Defibrotide has shown promising efficacy treating hepatic VOD/SOS with MOF in phase 2 studies. This phase 3 study investigated safety and efficacy of defibrotide in patients with established hepatic VOD/SOS and advanced MOF. Patients (n = 102) given defibrotide 25 mg/kg per day were compared with 32 historical controls identified out of 6867 medical charts of HSCT patients by blinded independent reviewers. Baseline characteristics between groups were well balanced. The primary endpoint was survival at day +100 post-HSCT; observed rates equaled 38.2% in the defibrotide group and 25% in the controls (23% estimated difference; 95.1% confidence interval [CI], 5.2-40.8;P= .0109, using a propensity-adjusted analysis). Observed day +100 complete response (CR) rates equaled 25.5% for defibrotide and 12.5% for controls (19% difference using similar methodology; 95.1% CI, 3.5-34.6;P= .0160). Defibrotide was generally well tolerated with manageable toxicity. Related adverse events (AEs) included hemorrhage or hypotension; incidence of common hemorrhagic AEs (including pulmonary alveolar [11.8% and 15.6%] and gastrointestinal bleeding [7.8% and 9.4%]) was similar between the defibrotide and control groups, respectively. Defibrotide was associated with significant improvement in day +100 survival and CR rate. The historical-control methodology offers a novel, meaningful approach for phase 3 evaluation of orphan diseases associated with high mortality. This trial was registered at www.clinicaltrials.gov as #.

Defibrotide for Patients with Hepatic Veno-Occlusive Disease/Sinusoidal Obstruction Syndrome: Interim Results from a Treatment IND Study.

Hepatic veno-occlusive disease, or sinusoidal obstruction syndrome (VOD/SOS), is a serious and potentially fatal complication of conditioning for hematopoietic stem cell transplantation (HSCT) or of chemotherapy regimens alone. Defibrotide is a complex mixture of single-stranded polydeoxyribonucleotides that is approved in the United States for treating hepatic VOD/SOS with renal or pulmonary dysfunction post-HSCT and in the European Union, Israel, and South Korea for treating severe hepatic VOD/SOS post-HSCT. Defibrotide was previously available in the United States as an investigational drug through a treatment protocol (treatment IND) study. Interim results of that large, treatment IND study of patients with VOD/SOS and with or without multiorgan dysfunction (MOD; also known as multiorgan failure) are presented here. Defibrotide was administered i.v. at 6.25 mg/kg every 6 hours (25 mg/kg/day), with a recommended treatment duration of at least 21 days. Enrolled patients (n = 681) were diagnosed with VOD/SOS based on Baltimore or modified Seattle criteria or liver biopsy analysis. Among the 573 HSCT recipients, 288 (50.3%; 95% confidence interval [CI], 46.2% to 54.4%) were alive at day +100 post-HSCT. Day +100 survival for the pediatric (≤16 years) and adult (>16 years) subgroups was 54.5% (95% CI, 49.1% to 60.0%; n = 174 of 319) and 44.9% (95% CI, 38.8% to 51.0%; n = 114 of 254), respectively. In the MOD subgroup, 159 of 351 patients (45.3%; 95% CI, 40.1% to 50.5%) of patients were alive at day +100 post-HSCT. Treatment with defibrotide was generally well tolerated, and drug-related toxicities were consistent with previous studies. Adverse events were reported in 69.6% of safety-evaluable patients (399 of 573). Other than VOD/SOS and associated MOD symptoms, the most commonly reported treatment-emergent adverse event was hypotension (13.8%). Day +100 survival results observed in this trial were consistent with results seen in previous trials of defibrotide for VOD/SOS in adult and pediatric patients. These data support the potential benefit of defibrotide in treating a VOD/SOS patient population that includes those with and without MOD.

Earlier defibrotide initiation post-diagnosis of veno-occlusive disease/sinusoidal obstruction syndrome improves Day +100 survival following haematopoietic stem cell transplantation.

Hepatic veno-occlusive disease/sinusoidal obstruction syndrome (VOD/SOS) is a progressive, potentially fatal complication of conditioning for haematopoietic stem cell transplant (HSCT). The VOD/SOS pathophysiological cascade involves endothelial-cell activation and damage, and a prothrombotic-hypofibrinolytic state. Severe VOD/SOS (typically characterized by multi-organ dysfunction) may be associated with >80% mortality. Defibrotide is approved for treating severe hepatic VOD/SOS post-HSCT in the European Union, and for hepatic VOD/SOS with renal or pulmonary dysfunction post-HSCT in the United States. Previously, defibrotide (25 mg/kg/day in 4 divided doses for a recommended ≥21 days) was available through an expanded-access treatment protocol for patients with VOD/SOS. Data from this study were examined post-hoc to determine if the timing of defibrotide initiation post-VOD/SOS diagnosis affected Day +100 survival post-HSCT. Among 573 patients, defibrotide was started on the day of VOD/SOS diagnosis in approximately 30%, and within 7 days in >90%. The relationship between Day +100 survival and treatment initiation before/after specific days post-diagnosis showed superior survival when treatment was initiated closer to VOD/SOS diagnosis with a statistically significant trend over time for better outcomes with earlier treatment initiation (P < 0·001). These results suggest that initiation of defibrotide should not be delayed after diagnosis of VOD/SOS.

Prolonged survival in patients with breast cancer and a history of brain metastases: results of a preplanned subgroup analysis from the randomized phase III BEACON trial.

PURPOSE: Conventional chemotherapy has limited activity in patients with breast cancer and brain metastases (BCBM). Etirinotecan pegol (EP), a novel long-acting topoisomerase-1 inhibitor, was designed using advanced polymer technology to preferentially accumulate in tumor tissue including brain metastases, providing sustained cytotoxic SN38 levels. METHODS: The phase 3 BEACON trial enrolled 852 women with heavily pretreated locally recurrent or metastatic breast cancer between 2011 and 2013. BEACON compared EP with treatment of physician's choice (TPC; eribulin, vinorelbine, gemcitabine, nab-paclitaxel, paclitaxel, ixabepilone, or docetaxel) in patients previously treated with anthracycline, taxane, and capecitabine, including those with treated, stable brain metastases. The primary endpoint, overall survival (OS), was assessed in a pre-defined subgroup of BCBM patients; an exploratory post hoc analysis adjusting for the diagnosis-specific graded prognostic assessment (GPA) index was also conducted. RESULTS: In the trial, 67 BCBM patients were randomized (EP, n = 36; TPC, n = 31). Treatment subgroups were balanced for baseline characteristics and GPA indices. EP was associated with a significant reduction in the risk of death (HR 0.51; P < 0.01) versus TPC; median OS was 10.0 and 4.8 months, respectively. Improvement in OS was observed in both poorer and better GPA prognostic groups. Survival rates at 12 months were 44.4% for EP versus 19.4% for TPC. Consistent with the overall BEACON population, fewer patients on EP experienced grade ≥3 toxicity (50 vs. 70%). CONCLUSIONS: The significant improvement in survival in BCBM patients provides encouraging data for EP in this difficult-to-treat subgroup of patients. A phase three trial of EP in BCBM patients is underway (ClinicalTrials.gov NCT02915744).

Etirinotecan pegol (NKTR-102) versus treatment of physician's choice in women with advanced breast cancer previously treated with an anthracycline, a taxane, and capecitabine (BEACON): a randomised, open-label, multicentre, phase 3 trial.

BACKGROUND: New options are needed for patients with heavily pretreated breast cancer. Etirinotecan pegol is a long-acting topoisomerase-I inhibitor that prolongs exposure to, but reduces the toxicity of, SN38 (the active metabolite of irinotecan). We assessed whether etirinotecan pegol is superior to currently available treatments for patients with previously treated, locally recurrent or metastatic breast cancer. METHODS: In this open-label, multicentre, randomised phase 3 study (BEACON; BrEAst Cancer Outcomes with NKTR-102), conducted at 135 sites in 11 countries, patients with locally recurrent or metastatic breast cancer previously treated with an anthracycline, a taxane, and capecitabine (and two to five previous regimens for advanced disease) were randomly assigned (1:1) centrally via an interactive response system to etirinotecan pegol (145 mg/m(2) as a 90-min intravenous infusion every 3 weeks) or single-drug treatment of physician's choice. Patients with stable brain metastases and an Eastern Cooperative Oncology Group performance status of 0-1 were eligible. Randomisation was stratified with a permuted block scheme by region, previous eribulin, and receptor status. After randomisation, patients and investigators were aware of treatment assignments. The primary endpoint was overall survival in the intention-to-treat population. This study is registered with ClinicalTrials.gov, number NCT01492101. FINDINGS: Between Dec 19, 2011, and Aug 20, 2013, 852 patients were randomly assigned; 429 to etirinotecan pegol and 423 to treatment of physician's choice. There was no significant difference in overall survival between groups (median 12·4 months [95% CI 11·0-13·6] for the etirinotecan pegol group vs 10·3 months [9·0-11·3] for the treatment of physician's choice group; hazard ratio 0·87 [95% CI 0·75-1·02]; p=0·084). The safety population includes the 831 patients who received at least one dose of assigned treatment (425 assigned to etirinotecan pegol and 406 to treatment of physician's choice). Serious adverse events were recorded for 128 (30%) patients treated with etirinotecan pegol and 129 (32%) treated with treatment of physician's choice. Fewer patients in the etirinotecan pegol group had grade 3 or worse toxicity than those in the treatment of physician's choice group (204 [48%] vs 256 [63%]; p<0·0001). The most common grade 3 or worse adverse events were diarrhoea (41 [10%] in the experimental group vs five [1%] in the control group), neutropenia (41 [10%] vs 125 [31%]), and peripheral neuropathy (two [<1%] vs 15 [4%]). Three patients in the etirinotecan pegol group died of treatment-related adverse events (pneumonia, myelodysplastic syndrome, and acute renal failure) and two in the treatment of physician's choice group (neutropenic sepsis and septic shock). INTERPRETATION: This trial did not demonstrate an improvement in overall survival for etirinotecan pegol compared to treatment of physician's choice in patients with heavily pre-treated advanced breast cancer. The toxicity profile noted in the etirinotecan pegol group differed from that in the control group. In view of the frequency of cross-resistance and overlapping toxicities noted with many available drugs and the need for effective drugs in highly refractory disease, etirinotecan pegol may warrant further research in some subgroups of patients. FUNDING: Nektar Therapeutics.

Two schedules of etirinotecan pegol (NKTR-102) in patients with previously treated metastatic breast cancer: a randomised phase 2 study.

BACKGROUND: New therapeutic options are needed for patients with heavily pretreated breast cancer. Etirinotecan pegol is a long-acting topoisomerase-I inhibitor designed to provide prolonged tumour-cell exposure to SN38, the active metabolite. We aimed to assess the efficacy and safety of two etirinotecan pegol dosing schedules in patients with previously treated metastatic breast cancer to determine an optimum dosing schedule for phase 3 trials. METHODS: In this randomised, two-stage, open-label phase 2 trial, we recruited patients aged 18 years or older who had received taxane therapy and undergone two or fewer previous chemotherapy regimens for metastatic breast cancer, with an Eastern Cooperative Oncology Group performance status of 0 or 1, from 18 sites in three countries. Eligible patients were randomly assigned (1:1) to etirinotecan pegol 145 mg/m(2) every 14 days or every 21 days. The primary endpoint was the proportion of patients with a confirmed objective response as defined by Response Evaluation Criteria in Solid Tumors version 1.0, analysed by intention to treat. Safety was assessed in all patients who received at least one dose of study drug. FINDINGS: 70 patients (35 in each group) were randomly assigned to treatment between Feb 17, 2009 and April 13, 2010. Of the 70 patients, 20 (29%; 95% CI 18·4-40·6) achieved an objective response (two [3%] had a complete response and 18 [26%] had a partial response). Ten patients on the 14-day schedule achieved an objective response (29%; 95% CI 14·6-46·3; eight partial responses, two complete responses) as did ten on the 21-day schedule (29%; 95% CI 14·6-46·3; all partial responses). The most common grade 3 or worse adverse events were delayed diarrhoea (seven [20%] of 35 patients on the 14-day schedule vs eight [23%] of 35 patients on the 21-day schedule), fatigue (five [14%] vs three [9%]), neutropenia (four [11%] vs four [11%]), and dehydration (three [9%] vs four [11%]); 14 [20%] patients discontinued treatment because of drug-related toxicity. There were two possible drug-related deaths (acute renal failure and septic shock) in the 14-day group; other drug-related serious adverse events reported by more than one patient included ten [14%] patients with diarrhoea (six [17%] patients on the 14-day schedule vs four [11%] on the 21-day schedule), six [9%] with dehydration (two [6%] vs four [11%]), two [3%] with nausea (two [6%] vs none), and two [3%] with vomiting (two [6%] vs none). INTERPRETATION: On the basis of the overall clinical data, pharmacokinetics, and tolerability profile, etirinotecan pegol 145 mg/m(2) every 21 days has been selected for a phase 3 trial against treatment of physician's choice in patients with advanced breast cancer.

A phase 1 study of KOS-862 (Epothilone D) co-administered with carboplatin (Paraplatin®) in patients with advanced solid tumors.

PURPOSE: To determine the maximally tolerated dose (MTD) and pharmacokinetics of carboplatin plus KOS-862 (Epothilone D) a novel cytotoxic macrolide capable of causing mitotic arrest, in patients with advanced solid malignancies. EXPERIMENTAL DESIGN: Patients who have progressed on standard regimens were treated at four different levels of KOS-862(mg/m(2))/Carboplatin(AUC): 50/5,75/5, 75/6 and 100/6 in a "3 + 3" phase I study study design to determine MTD. Patients received KOS-862 on Days 1 and 8, and carboplatin on day 1, of 3-week cycles. Pharmacokinetics of KOS-862 and Carboplatin were studied. RESULTS: Twenty-seven patients enrolled in the study. At the top dose level, 2 out of the 9 patients experienced Dose Limiting Toxicity. (grade 3 peripheral motor neuropathy in both patients) Twenty-seven patients had sufficient plasma data points for pharmacokinetic analysis Both the parent drug, KOS-862, and the major inactive metabolite Seco-D KOS-862 (KOS-1965) were quantified in plasma. Kinetics of KOS-862 were the same as seen in monotherapy studies using the same route and time of administration. Two patients had tumor response after study treatment. Ten of 20 evaluable patients had stable disease after 2 cycles of study treatment. The MTD in the present study was KOS-862 100 mg/m(2) + carboplatin AUC = 6. CONCLUSIONS: The pharmacokinetics of KOS-862 were similar in this combination study to those seen in previous monotherapy studies using the same route and time of administration. We have described the MTD of this schedule. The neurotoxicity seen with this regimen should be considered prior to its administration in unselected populations.

Phase I clinical, pharmacokinetic, and pharmacodynamic study of KOS-862 (Epothilone D) in patients with advanced solid tumors and lymphoma.

PURPOSE: To determine the maximum tolerated dose and safety of the epothilone, KOS-862, in patients with advanced solid tumors or lymphoma. PATIENTS AND METHODS: Patients were treated weekly for 3 out of 4 weeks (Schedule A) or 2 out of 3 weeks (Schedule B) with KOS-862 (16-120 mg/m(2)). Pharmacokinetic (PK) sampling was performed during cycles 1 and 2; pharmacodynamic (PD) assessment for microtubule bundle formation (MTBF) was performed after the 1st dose, only at or above 100 mg/m(2). RESULTS: Thirty-two patients were enrolled, and twenty-nine completed ≥1 cycle of therapy. Dose limiting toxicity [DLT] was observed at 120 mg/m(2). PK data were linear from 16 to 100 mg/m(2), with proportional increases in mean C(max) and AUC(tot) as a function of dose. Full PK analysis (mean ± SD) at 100 mg/m(2) revealed the following: half-life (t (½)) = 9.1 ± 2.2 h; volume of distribution (V(z)) = 119 ± 41 L/m(2); clearance (CL) = 9.3 ± 3.2 L/h/m(2). MTBF (n = 9) was seen in 40% of PBMCs within 1 h and in 15% of PBMC at 24-hours post infusion at 100 mg/m(2). Tumor shrinkage (n = 2, lymphoma), stable disease >3 months (n = 5, renal, prostate, oropharynx, cholangiocarcinoma, and Hodgkin lymphoma), and tumor marker reductions (n = 1, colorectal cancer/CEA) were observed. CONCLUSION: KOS-862 was well tolerated with manageable toxicity, favorable PK profile, and the suggestion of clinical activity. The maximum tolerated dose was determined to be 100 mg/m(2) weekly 3-on/1-off. MTBF can be demonstrated in PBMCs of patients exposed to KOS-862.

Treatment With Etirinotecan Pegol for Patients With Metastatic Breast Cancer and Brain Metastases: Final Results From the Phase 3 ATTAIN Randomized Clinical Trial.

Importance: Patients with breast cancer and brain metastases (BM) have a poor prognosis and high clinical need for novel treatments; however, historically, studies have often excluded these patients. Although the BEACON study did not meet its primary end point, treatment with etirinotecan pegol vs chemotherapy of the physician's choice for patients with advanced breast cancer demonstrated a significant improvement in overall survival (OS) for the prespecified patient subgroup with preexisting, pretreated, and nonprogressive BM. Objective: To compare clinical outcomes in patients with BM treated with etirinotecan pegol vs chemotherapy of the physician's choice in a confirmatory trial. Design, Setting, and Participants: This study was a phase 3, open-label, randomized clinical trial (ATTAIN) in patients with metastatic breast cancer and a history of stable pretreated BM who experienced disease progression while receiving chemotherapy in the metastatic setting. The trial took place at 47 sites in 10 countries, and patients were enrolled between March 7, 2017, and November 6, 2019. Interventions: Patients were randomized to receive etirinotecan pegol, 145 mg/m2, every 21 days or chemotherapy (eribulin, ixabepilone, vinorelbine, gemcitabine, paclitaxel, docetaxel, or nab-paclitaxel). Main Outcomes and Measures: The primary end point was OS. Key secondary end points included progression-free survival, objective response rate, duration of response, and the clinical benefit rate. Results: A total of 178 female patients (9 [5.1%] Asian, 8 [4.5%] Black or African American, and 123 [69.1] White individuals) were randomized to receive treatment with etirinotecan pegol (92 [51.7%]; median [range] age, 53 [27-79] years) or chemotherapy (86 [48.3%]; median [range] age, 52 [24-77] years). Median OS was similar in both groups (etirinotecan pegol, 7.8 months; chemotherapy, 7.5 months; hazard ratio [HR], 0.90; 95% CI, 0.61-1.33; P = .60). Median progression-free survival for non-central nervous system metastases per blinded independent central review for etirinotecan pegol vs chemotherapy was 2.8 and 1.9 months (HR, 0.72; 95% CI, 0.45-1.16; P = .18) and 3.9 vs 3.3 months, respectively, for central nervous system metastases (HR, 0.59; 95% CI, 0.33-1.05; P = .07). Safety profiles between the groups were largely comparable. Conclusions and Relevance: The results of the ATTAIN randomized clinical trial found no statistically significant difference in outcomes between treatment with etirinotecan pegol and chemotherapy in patients with BM. However, this study represents one of the largest published trials dedicated to patients with breast cancer and BM and may help to inform further research. Trial Registration: ClinicalTrials.gov Identifier: NCT02915744.

Phase I, First-in-Human Study of the Probody Therapeutic CX-2029 in Adults with Advanced Solid Tumor Malignancies.

PURPOSE: PROCLAIM-CX-2029 is a phase I first-in-human study of CX-2029, a Probody-drug conjugate targeting CD71 (transferrin receptor 1) in adults with advanced solid tumors. Although the transferrin receptor is highly expressed across multiple tumor types, it has not been considered a target for antibody-drug conjugates (ADCs) due to its broad expression on normal cells. CX-2029 is a masked form of a proprietary anti-CD71 antibody conjugated to monomethyl auristatin E, designed to be unmasked in the tumor microenvironment by tumor-associated proteases, therefore limiting off-tumor toxicity and creating a therapeutic window for this previously undruggable target. PATIENTS AND METHODS: This was a dose-escalation, multicenter trial to evaluate the safety, pharmacokinetics, pharmacodynamics, and antitumor activity of CX-2029. The primary endpoint was to determine the maximum tolerated dose (MTD) and cycle 1 dose-limiting toxicity (DLT). CX-2029 was administered i.v. every 3 weeks. RESULTS: Forty-five patients were enrolled in eight dose levels. No DLTs were reported in the dose escalation through 4 mg/kg. At 5 mg/kg, there were two DLTs (febrile neutropenia and pancytopenia). Following expansion of the 4 mg/kg dose to six patients, two additional DLTs were observed (infusion-related reaction and neutropenia/anemia). Both the 4 and 5 mg/kg doses were declared above the maximum tolerated dose. The recommended phase II dose is 3 mg/kg. The most common dose-dependent hematologic toxicities were anemia and neutropenia. Confirmed partial responses were observed in three patients, all with squamous histologies. CONCLUSIONS: The Probody therapeutic platform enables targeting CD71, a previously undruggable ADC target, at tolerable doses associated with clinical activity.See related commentary by Oberoi and Garralda, p. 4459.

CX-072 (pacmilimab), a Probody ® PD-L1 inhibitor, in advanced or recurrent solid tumors (PROCLAIM-CX-072): an open-label dose-finding and first-in-human study.

BACKGROUND: Probody® therapeutics are antibody prodrugs that are activated in the tumor microenvironment by tumor-associated proteases, thereby restricting the activity to the tumor microenvironment and minimizing 'off-tumor' toxicity. We report dose-escalation and single-agent expansion phase data from the first-in-human study of CX-072 (pacmilimab), a Probody checkpoint inhibitor directed against programmed death-ligand 1 (PD-L1). METHODS: In the dose-escalation phase of this multicenter, open-label study (NCT03013491), adults with advanced solid tumors (naive to programmed-death-1/PD-L1 or cytotoxic T-lymphocyte-associated antigen 4 inhibitors) were enrolled into one of seven dose-escalation cohorts, with pacmilimab administered intravenously every 14 days. The primary endpoints were safety and determination of the maximum tolerated dose (MTD). In the expansion phase, patients with one of six prespecified malignancies (triple-negative breast cancer [TNBC]; anal squamous cell carcinoma [aSCC]; cutaneous SCC [cSCC]; undifferentiated pleomorphic sarcoma [UPS]; small bowel adenocarcinoma [SBA]; and thymic epithelial tumor [TET]); or high tumor mutational burden (hTMB) tumors were enrolled. The primary endpoint was objective response (Response Evaluation Criteria In Solid Tumors v.1.1). RESULTS: An MTD was not reached with doses up to 30 mg/kg. A recommended phase 2 dose (RP2D) of 10 mg/kg was chosen based on pharmacokinetic and pharmacodynamic findings in the expansion phase. Ninety-eight patients enrolled in the expansion phase: TNBC (n=14), aSCC (n=14), cSCC (n=14), UPS (n=20), SBA (n=14), TET (n=8), and hTMB tumors (n=14). Of 114 patients receiving pacmilimab at the RP2D, grade ≥3 treatment-related adverse events (TRAEs) were reported in 10 patients (9%), serious TRAEs in six patients (5%), and treatment discontinuation due to TRAEs in two patients (2%). Grade ≥3 immune-related AEs occurred in two patients (rash, myocarditis). High PD-L1 expression (ie, >50% Tumor Proportion Score) was observed in 22/144 (19%) patients. Confirmed objective responses were observed in patients with cSCC (n=5, including one complete response), hTMB (n=4, including one complete response), aSCC (n=2), TNBC (n=1), UPS (n=1), and anaplastic thyroid cancer (n=1). CONCLUSIONS: Pacmilimab can be administered safely at the RP2D of 10 mg/kg every 14 days. At this dose, pacmilimab had a low rate of immune-mediated toxicity and showed signs of antitumor activity in patients not selected for high PD-L1 expression. TRIAL REGISTRATION NUMBER: NCT03013491.

Bempegaldesleukin (NKTR-214) plus Nivolumab in Patients with Advanced Solid Tumors: Phase I Dose-Escalation Study of Safety, Efficacy, and Immune Activation (PIVOT-02).

This single-arm, phase I dose-escalation trial (NCT02983045) evaluated bempegaldesleukin (NKTR-214/BEMPEG), a CD122-preferential IL2 pathway agonist, plus nivolumab in 38 patients with selected immunotherapy-naïve advanced solid tumors (melanoma, renal cell carcinoma, and non-small cell lung cancer). Three dose-limiting toxicities were reported in 2 of 17 patients during dose escalation [hypotension (n = 1), hyperglycemia (n = 1), metabolic acidosis (n = 1)]. The most common treatment-related adverse events (TRAE) were flu-like symptoms (86.8%), rash (78.9%), fatigue (73.7%), and pruritus (52.6%). Eight patients (21.1%) experienced grade 3/4 TRAEs; there were no treatment-related deaths. Total objective response rate across tumor types and dose cohorts was 59.5% (22/37), with 7 complete responses (18.9%). Cellular and gene expression analysis of longitudinal tumor biopsies revealed increased infiltration, activation, and cytotoxicity of CD8+ T cells, without regulatory T-cell enhancement. At the recommended phase II dose, BEMPEG 0.006 mg/kg plus nivolumab 360 mg every 3 weeks, the combination was well tolerated and demonstrated encouraging clinical activity irrespective of baseline PD-L1 status. SIGNIFICANCE: These data show that BEMPEG can be successfully combined with a checkpoint inhibitor as dual immunotherapy for a range of advanced solid tumors. Efficacy was observed regardless of baseline PD-L1 status and baseline levels of tumor-infiltrating lymphocytes, suggesting therapeutic potential for patients with poor prognostic risk factors for response to PD-1/PD-L1 blockade.See related commentary by Rouanne et al., p. 1097.This article is highlighted in the In This Issue feature, p. 1079.

A Phase II Study of Talazoparib after Platinum or Cytotoxic Nonplatinum Regimens in Patients with Advanced Breast Cancer and Germline BRCA1/2 Mutations (ABRAZO).

PURPOSE: To assess talazoparib activity in germline BRCA1/2 mutation carriers with advanced breast cancer. PATIENTS AND METHODS: ABRAZO (NCT02034916) was a two-cohort, two-stage, phase II study of talazoparib (1 mg/day) in germline BRCA mutation carriers with a response to prior platinum with no progression on or within 8 weeks of the last platinum dose (cohort 1) or ≥3 platinum-free cytotoxic regimens (cohort 2) for advanced breast cancer. Primary endpoint was confirmed objective response rate (ORR) by independent radiological assessment. RESULTS: We enrolled 84 patients (cohort 1, n = 49; cohort 2, n = 35) from May 2014 to February 2016. Median age was 50 (range, 31-75) years. Triple-negative breast cancer (TNBC) incidence was 59% (cohort 1) and 17% (cohort 2). Median number of prior cytotoxic regimens for advanced breast cancer was two and four, respectively. Confirmed ORR was 21% [95% confidence interval (CI), 10-35; cohort 1] and 37% [95% CI, 22-55; cohort 2]. Median duration of response was 5.8 and 3.8 months, respectively. Confirmed ORR was 23% (BRCA1), 33% (BRCA2), 26% (TNBC), and 29% (hormone receptor-positive). The most common all-grade adverse events (AE) included anemia (52%), fatigue (45%), and nausea (42%). Talazoparib-related AEs led to drug discontinuation in 3 (4%) patients. In an exploratory analysis, longer platinum-free interval was associated with higher response rate in cohort 1 (0% ORR with interval <8 weeks; 47% ORR with interval >6 months). CONCLUSIONS: Talazoparib exhibited promising antitumor activity in patients with advanced breast cancer and germline BRCA mutation.

Randomized study of etirinotecan pegol versus irinotecan as second-line treatment for metastatic colorectal cancer.

PURPOSE: Etirinotecan pegol (EP) is a long-acting topoisomerase-I inhibitor designed to provide sustained exposure to SN-38 (active metabolite of irinotecan). This phase II study compared EP versus irinotecan as second-line treatment for KRAS-mutant, irinotecan-naïve, metastatic colorectal cancer (mCRC). METHODS: Patients were randomized to EP 145 mg/m2 or irinotecan 350 mg/m2 Q21d until disease progression/unacceptable toxicity. The primary endpoint was progression-free survival (PFS) with response determined by central radiologic review (RECIST version 1.1). RESULTS: The study was terminated before completing accrual due to evolving standards of care. Eighty-three patients were randomized. Median PFS was longer with EP versus irinotecan (4.0 versus 2.8 months, respectively; HR 0.65; 95% CI 0.40-1.04; P = 0.07). Six-month PFS rates were 32.8 and 15.4%, respectively. Median OS was 9.6 and 8.4 months in EP and irinotecan arms, respectively (HR 0.91; 95% CI 0.56-1.49). ORRs were 10 and 5%, respectively (P = 0.676); median DOR was significantly longer in EP arm (7.9 versus 1.4 months; P = 0.018). The most common grade-3/4 adverse events for EP and irinotecan were diarrhea (21 vs 20%), neutropenia (10 vs 22%), abdominal pain (14 vs 5%), nausea (14 vs 2%), and vomiting (12 vs 7%), respectively. CONCLUSION: EP is active and safe for second-line treatment of KRAS-mutant, irinotecan-naïve mCRC.

Health-related quality of life in patients with locally recurrent or metastatic breast cancer treated with etirinotecan pegol versus treatment of physician's choice: Results from the randomised phase III BEACON trial.

BACKGROUND: Health-related quality of life (HRQoL) enhances understanding of treatment effects that impact clinical decision-making. Although the primary end-point was not achieved, the BEACON (BrEAst Cancer Outcomes with NKTR-102) trial established etirinotecan pegol, a long-acting topoisomerase-1 (TOP1) inhibitor, as a promising therapeutic for patients with advanced/metastatic breast cancer (MBC) achieving clinically meaningful benefits in median overall survival (OS) for patients with stable brain metastases, with liver metastases or ≥ 2 sites of metastatic disease compared to treatment of physician's choice (TPC). Reported herein are the findings from the preplanned secondary end-point of HRQoL. PATIENTS AND METHODS: HRQoL, assessed by European Organisation for Research and Treatment of Cancer (EORTC) Quality of Life Questionnaire-Core 30 (QLQ-C30) (version 3.0) supplemented by the breast cancer-specific Quality of Life Questionnaire (QLQ-BR23), was evaluated post randomisation in 733 of 852 patients with either anthracycline-, taxane- and capecitabine-pretreated locally recurrent or MBC randomised to etirinotecan pegol (n = 378; 145 mg/m2 every 3 weeks (q3wk)) or single-agent TPC (n = 355). Patients completed assessments at screening, every 8 weeks (q8wk) during treatment, and end-of-treatment. Changes from baseline were analysed, and the proportions of patients achieving differences (≥5 points) in HRQoL scores were compared. RESULTS: Differences were seen favouring etirinotecan pegol up to 32 weeks for global health status (GHS) and physical functioning scales (P < 0.02); numerical improvement was reported in other functional scales. The findings from HRQoL symptom scales were consistent with adverse event profiles; etirinotecan pegol was associated with worsening gastrointestinal symptoms whereas TPC was associated with worsened dyspnoea and other systemic side-effects. Analysis of GHS and physical functioning at disease progression showed a decline in HRQoL in both treatment arms, with a mean change from baseline of -9.4 and -10.8 points, respectively. CONCLUSION: There was evidence of benefit associated with etirinotecan pegol compared with current standard of care agents in multiple HRQoL measurements, including global health status and physical functioning, despite worse gastrointestinal symptoms (e.g. diarrhoea). Patients in both arms had a decline in HRQoL at disease progression. STUDY NUMBER: NCT01492101.

Phase I dose-escalating study of SU11654, a small molecule receptor tyrosine kinase inhibitor, in dogs with spontaneous malignancies.

PURPOSE: The purpose of the following study was to investigate the safety and efficacy of the novel multitargeted indolinone receptor tyrosine kinase (RTK) inhibitor, SU11654, using a canine model of spontaneous tumors. This p.o. bioavailable compound exhibits potent inhibitory activity against members of the split kinase family of RTKs, including vascular endothelial growth factor receptor, platelet-derived growth factor receptor, Kit, and Flt-3, resulting in both direct antitumor and antiangiogenic activity. EXPERIMENTAL DESIGN: This was a Phase I trial in which successive cohorts of dogs with spontaneous tumors that had failed standard treatment regimens received escalating doses of SU11654 as oral therapy. Pharmacokinetics, toxicity, and tumor response were assessed. RESULTS: Fifty-seven dogs with a variety of cancers were enrolled; of these, 10 experienced progressive disease within the first 3 weeks. Measurable objective responses were observed in 16 dogs (including 6 complete responses), primarily in mast cell tumors (n = 11), mixed mammary carcinomas (n = 2), soft tissue sarcomas (n = 2), and multiple myeloma (n = 1), for an overall response rate of 28% (16 of 57). Stable disease of sufficient duration to be considered clinically meaningful (>10 weeks) was seen in an additional 15 dogs, for a resultant overall biological activity of 54% (31 of 57). CONCLUSIONS: This study provides the first evidence that p.o. administered kinase inhibitors can exhibit activity against a variety of spontaneous malignancies. Given the similarities of canine and human cancers with regard to tumor biology and the presence of analogous RTK dysregulation, it is likely that such agents will demonstrate comparable antineoplastic activity in people.

Effects of SU5416, a small molecule tyrosine kinase receptor inhibitor, on FLT3 expression and phosphorylation in patients with refractory acute myeloid leukemia.

Acute myeloid leukemia (AML) is associated with dysregulated hematopoietic cell proliferation and increased bone marrow angiogenesis, each regulated by signaling through receptor tyrosine kinases (RTKs). SU5416 is a small molecule inhibitor of VEGF receptors, c-kit and FLT3 and therefore provides a novel opportunity to target both angiogenesis and proliferation in AML. SU5416 was assessed in a phase II hematological malignancy trial in the US, where partial responses were observed in two of 33 patients. Since AML provides a unique platform to evaluate mechanism of action of small molecule inhibitors, investigation of the effect of SU5416 on FLT3 expression and phosphorylation in blood and bone marrow was an additional focus of this trial. Phosphorylated FLT3 was detected by immunoprecipitation/Western analysis in peripheral blood samples from 17 of 22 patients, and seven exhibited strong inhibition of phosphorylation immediately following a 1h SU5416 infusion, demonstrating that SU5416 can modulate RTK phosphorylation in humans. Although no clear correlation with clinical response was observed, analysis of patient plasma drug levels suggested that a threshold SU5416 concentration of 15 microM was associated with FLT3 inhibition. This observation was supported by data from an ex vivo model where AML cells were spiked into human blood, established to mimic the clinical setting and enable more rigorous analysis of effect of SU5416. In addition, FLT3 protein levels were downregulated in patient bone marrow samples, analyzed by an RIA assay. To identify putative predictors of response, patient plasma was analyzed for levels of secreted ligands of SU5416 targets; SCF and FLT3 ligand. Baseline levels of SCF in patients with stable or progressive disease were significantly higher than those in normal donors, whereas FLT3 ligand levels in patients who exhibited progressive disease were significantly lower than those in normal donors. The translational and clinical analyses described in this report provide some insights into the mechanism and duration of action of SU5416.