Safety And Efficacy Of Combination Lurbinectedin Plus Doxorubicin From A Phase 1b Trial In Patients With Advanced/Metastatic Soft Tissue Sarcoma.

PURPOSE: While cytotoxic chemotherapy is standard first-line treatment for patients with metastatic soft tissue sarcoma (STS), clinical outcomes remain suboptimal. Our prior study showed lurbinectedin plus doxorubicin is well-tolerated with promising clinical activity in STS. We designed this phase 1b trial to optimize dosing as the basis for a randomized trial in leiomyosarcoma (LMS) and to further explore the safety profile and efficacy signal. PATIENTS AND METHODS: Patients had advanced/metastatic STS and no prior anthracycline/lurbinectedin/trabectedin. Escalation followed a 3+3 design with 3-week cycles: lurbinectedin (3.2 mg/m2 day 1) and two doxorubicin levels (DL1: 25 mg/m2 day 1; DL2 25 mg/m2 days 1 and 8). The primary objectives were to identify the maximum tolerated dose (MTD) and recommended dose for subsequent randomized trials. RESULTS: Ten patients were enrolled in a 6-month period. The most common treatment-emergent adverse events (TEAE) were grade (G) 2 fatigue and nausea, and G2 cytopenias with no febrile neutropenia events. There were 2 dose-limiting toxicities (DLTs) at DL2 (day 8 [G2 ALT/AST increase, G3 neutropenia]), and 1 DLT in DL1 (G3 ALT increase). These were reversible and all patients continued the study. DL1 was chosen for further study. At the time of data cutoff, the estimated median PFS is 16.5 months (95%CI 6.0-ND). The ORR was 60% (6/10 confirmed partial responses [PR]). CONCLUSIONS: In this phase 1b study, the recommended dose is lurbinectedin 3.2 mg/m2 in combination with doxorubicin 25 mg/m2 every 3 weeks. The study combination was well-tolerated and demonstrated intriguing clinical activity.

A Single Arm Phase 2 Trial of Trametinib in Patients With Locally Advanced or Metastatic Epithelioid Hemangioendothelioma.

PURPOSE: Epithelioid hemangioendothelioma (EHE) is a rare vascular cancer with pathogenic TAZ-CAMTA1 operating as an oncogenic driver through activation of MAPK pathway. Trametinib is an inhibitor of MEK, a critical kinase in the MAPK pathway. We sought to evaluate the effect of trametinib in patients with EHE. PATIENTS AND METHODS: A phase 2 trial of trametinib was conducted in patients with locally advanced or metastatic EHE. Eligibility requirements included evidence of tumor progression or presence of EHE-related pain requiring opiates for management prior to enrollment. The primary endpoint was objective response rate (ORR) per RECIST1.1 in cases with TAZ-CAMTA1 confirmed by fusion-FISH. Secondary objectives were to estimate ORR for all patients, median PFS, 2-year OS rate, patient safety, and change in patient-reported global health and pain scores per PROMIS questionnaires. RESULTS: 44 patients enrolled and 42 started trametinib. TAZ-CAMTA1 was detected in 27 tumor samples. The ORR was 3.7% (95% CI: 0.094, 19.0), median PFS was 10.4 months (95% CI: 7.1, NA), and 2-year OS rate was 33.3% (95% CI: 19.1, 58.2) in the target population. Median pain intensity and interference scores improved significantly after 4 weeks of trametinib in patients using opiates. Common AEs related to trametinib were rash, fatigue, nausea/vomiting, diarrhea/constipation, alopecia and edema; one Grade 5 ARDS/pneumonitis was related to trametinib. CONCLUSIONS: Trametinib was associated with reduction in EHE-related pain and median PFS of more than 6 months providing palliative benefit in patients with advanced EHE, but the trial did not meet the ORR goal.

KIT ATP-Binding Pocket/Activation Loop Mutations in GI Stromal Tumor: Emerging Mechanisms of Kinase Inhibitor Escape.

PURPOSE: Imatinib resistance in GI stromal tumors (GISTs) is primarily caused by secondary KIT mutations, and clonal heterogeneity of these secondary mutations represents a major treatment obstacle. KIT inhibitors used after imatinib have clinical activity, albeit with limited benefit. Ripretinib is a potent inhibitor of secondary KIT mutations in the activation loop (AL). However, clinical benefit in fourth line remains limited and the molecular mechanisms of ripretinib resistance are largely unknown. PATIENTS AND METHODS: Progressing lesions of 25 patients with GISTs refractory to ripretinib were sequenced for KIT resistance mutations. Resistant genotypes were validated and characterized using novel cell line models and in silico modeling. RESULTS: GISTs progressing on ripretinib were enriched for secondary mutations in the ATP-binding pocket (AP), which frequently occur in cis with preexisting AL mutations, resulting in highly resistant AP/AL genotypes. AP/AL mutations were rarely observed in a cohort of progressing GIST samples from the preripretinib era but represented 50% of secondary KIT mutations in patients with tumors resistant to ripretinib. In GIST cell lines harboring secondary KIT AL mutations, the sole genomic escape mechanisms during ripretinib drug selection were AP/AL mutations. Ripretinib and sunitinib synergize against mixed clones with secondary AP or AL mutants but do not suppress clones with AP/AL genotypes. CONCLUSION: Our findings underscore that KIT remains the central oncogenic driver even in late lines of GIST therapy. KIT-inhibitor combinations may suppress resistance because of secondary KIT mutations. However, the emergence of KIT AP/AL mutations after ripretinib treatment calls for new strategies in the development of next-generation KIT inhibitors.

Phase II Study of Eribulin plus Pembrolizumab in Metastatic Soft-tissue Sarcomas: Clinical Outcomes and Biological Correlates.

PURPOSE: Eribulin modulates the tumor-immune microenvironment via cGAS-STING signaling in preclinical models. This non-randomized phase II trial evaluated the combination of eribulin and pembrolizumab in patients with soft-tissue sarcomas (STS). PATIENTS AND METHODS: Patients enrolled in one of three cohorts: leiomyosarcoma (LMS), liposarcomas (LPS), or other STS that may benefit from PD-1 inhibitors, including undifferentiated pleomorphic sarcoma (UPS). Eribulin was administered at 1.4 mg/m2 i.v. (days 1 and 8) with fixed-dose pembrolizumab 200 mg i.v. (day 1) of each 21-day cycle, until progression, unacceptable toxicity, or completion of 2 years of treatment. The primary endpoint was the 12-week progression-free survival rate (PFS-12) in each cohort. Secondary endpoints included the objective response rate, median PFS, safety profile, and overall survival (OS). Pretreatment and on-treatment blood specimens were evaluated in patients who achieved durable disease control (DDC) or progression within 12 weeks [early progression (EP)]. Multiplexed immunofluorescence was performed on archival LPS samples from patients with DDC or EP. RESULTS: Fifty-seven patients enrolled (LMS, n = 19; LPS, n = 20; UPS/Other, n = 18). The PFS-12 was 36.8% (90% confidence interval: 22.5-60.4) for LMS, 69.6% (54.5-89.0) for LPS, and 52.6% (36.8-75.3) for UPS/Other cohorts. All 3 patients in the UPS/Other cohort with angiosarcoma achieved RECIST responses. Toxicity was manageable. Higher IFNα and IL4 serum levels were associated with clinical benefit. Immune aggregates expressing PD-1 and PD-L1 were observed in a patient that completed 2 years of treatment. CONCLUSIONS: The combination of eribulin and pembrolizumab demonstrated promising activity in LPS and angiosarcoma.

Ripretinib versus sunitinib in gastrointestinal stromal tumor: ctDNA biomarker analysis of the phase 3 INTRIGUE trial.

INTRIGUE was an open-label, phase 3 study in adult patients with advanced gastrointestinal stromal tumor who had disease progression on or intolerance to imatinib and who were randomized to once-daily ripretinib 150 mg or sunitinib 50 mg. In the primary analysis, progression-free survival (PFS) with ripretinib was not superior to sunitinib. In clinical and nonclinical studies, ripretinib and sunitinib have demonstrated differential activity based on the exon location of KIT mutations. Therefore, we hypothesized that mutational analysis using circulating tumor DNA (ctDNA) might provide further insight. In this exploratory analysis (N = 362), baseline peripheral whole blood was analyzed by a 74-gene ctDNA next-generation sequencing-based assay. ctDNA was detected in 280/362 (77%) samples with KIT mutations in 213/362 patients (59%). Imatinib-resistant mutations were found in the KIT ATP-binding pocket (exons 13/14) and activation loop (exons 17/18). Mutational subgroup assessment showed 2 mutually exclusive populations with differential treatment effects. Patients with only KIT exon 11 + 13/14 mutations (ripretinib, n = 21; sunitinib, n = 20) had better PFS with sunitinib versus ripretinib (median, 15.0 versus 4.0 months). Patients with only KIT exon 11 + 17/18 mutations (ripretinib, n = 27; sunitinib, n = 25) had better PFS with ripretinib versus sunitinib (median, 14.2 versus 1.5 months). The results of this exploratory analysis suggest ctDNA sequencing may improve the prediction of the efficacy of single-drug therapies and support further evaluation of ripretinib in patients with KIT exon 11 + 17/18 mutations. ClinicalTrials.gov identifier: NCT03673501.

SAR-096: Phase II Clinical Trial of Ribociclib in Combination with Everolimus in Advanced Dedifferentiated Liposarcoma (DDL) and Leiomyosarcoma (LMS).

PURPOSE: Dedifferentiated liposarcoma (DDL) and leiomyosarcoma (LMS) are two common subtypes of soft-tissue sarcoma, a rare group of diseases for which new treatments are needed. Chemotherapy remains the standard option for advanced disease. Targeting cyclin-dependent kinase 4 and 6 (CDK4/6) in DDL and mTOR in LMS is of biologic interest. When combined, the CDK4 inhibitor ribociclib and the mTOR inhibitor everolimus have shown synergistic growth inhibition in multiple tumor models, suggesting that this combination could be beneficial in patients. PATIENTS AND METHODS: This was a single arm, open label, multicenter phase II study of the combination of ribociclib and everolimus. Patients were enrolled into one of two cohorts: DDL or LMS with intact Rb. The primary endpoint was progression-free rate (PFR) at 16 weeks. Secondary endpoints included progression-free survival (PFS) and overall survival, safety and biomarker analyses. RESULTS: In the DDL cohort, 33.3% [95% confidence interval (CI), 15.6%-55.3%] of patients were progression-free at 16 weeks. Median PFS in this cohort was 15.4 weeks (95% CI, 8-36 weeks) with 2 partial responses. In the LMS cohort the PFR at 16 weeks was 29.2% (95% CI, 12.6%-51.1%). Median PFS in this cohort was 15.7 weeks (95% CI, 7.7-NA). Most common toxicities included fatigue (66.7%), anorexia (43.8%), and hyperglycemia (43.8%). Concordance between Rb testing methodologies was poor. CONCLUSIONS: The combination of ribociclib and everolimus demonstrates activity in DDL with prolonged stable disease (≥16 weeks) meeting the primary endpoint. Notably partial responses were observed. The primary endpoint was not reached in the LMS cohort. The combination was well tolerated with expected side effects.

Clinical Benefit of Avapritinib in KIT-Mutant Gastrointestinal Stromal Tumors: A Post Hoc Analysis of the Phase I NAVIGATOR and Phase I/II CS3007-001 Studies.

PURPOSE: The efficacy of the selective KIT/PDGFRA inhibitor avapritinib (300 mg once daily) was explored in patients with non-PDGFRA-mutant gastrointestinal stromal tumors (GISTs) from the phase I NAVIGATOR and phase I/II CS3007-001 trials. PATIENTS AND METHODS: Adults with unresectable/metastatic, KIT-only-mutant GISTs and progression following ≥1 tyrosine kinase inhibitors (TKIs) were included in this post hoc analysis. Baseline mutational status was identified in tumor and plasma. Primary endpoints were objective response rate (ORR) and progression-free survival (PFS) by blinded independent radiology review per modified RECIST v1.1 in patients harboring KIT activation-loop mutations (KIT exons 17 or 18) without ATP binding-pocket mutations (KIT exons 13 or 14; ALposABPneg), and other KIT mutations (OTHERS). RESULTS: Sixty KIT ALposABPneg and 100 KIT OTHERS predominantly heavily pretreated patients (61.3% with ≥3 prior TKIs) were included. ORR was significantly higher in KIT ALposABPneg than KIT OTHERS patients (unadjusted: 26.7% vs. 12.0%; P = 0.0852; adjusted: 31.4% vs. 12.1%; P = 0.0047). Median PFS (mPFS) was significantly longer in KIT ALposABPneg patients compared with KIT OTHERS patients (unadjusted: 9.1 vs. 3.5 months; P = 0.0002; adjusted: 9.1 vs. 3.4 months; P < 0.0001), and longer in second- versus later-line settings (19.3 vs. 5.6-10.6 months). Benefit with avapritinib was observed in patients with KIT exon 9 mutations in the ≥4 line settings (mPFS: 5.6 and 3.7 months for 4 line and >4 line, respectively). CONCLUSIONS: Avapritinib showed greater antitumor activity in patients with GISTs harboring KIT ALposABPneg mutations versus KIT OTHERS, and may be considered in the former subpopulation. Patients with KIT exon 9 mutations may also benefit in ≥4 line settings.

Alliance A151945: Accrual and characteristics of adolescent and young adult patients in Alliance trials from 2000 to 2017.

BACKGROUND: Identifying patient- and disease-specific characteristics associated with clinical trial enrollment of adolescents and young adults (AYAs) with cancer may target efforts to improve accrual. METHODS: Alliance for Clinical Trials in Oncology (Alliance) trials opened from January 1, 2000, and closed before January 1, 2018, for common AYA cancers were identified. Proportions of AYAs (aged 18-39 years old) versus non-AYAs (aged ≥40 years old) enrolled by cancer type were summarized by descriptive statistics. Among studies with ≥20 AYAs enrolled, demographic and disease characteristics of AYAs versus non-AYAs were compared with χ2 and Kruskal-Wallis tests. A qualitative review was also conducted of therapeutic trials included in analysis in PubMed through December 31, 2021, that reported AYA-specific survival. RESULTS: Among 188 trials enrolling 40,396 patients, AYAs represented 11% (4468 of 40,396) of accrual. AYA accrual varied by cancer type (leukemia, 23.6%; breast, 9.9%; lymphoma, 14.8%; colorectal, 6.2%; central nervous system, 8.1%; melanoma, 11.8%; sarcoma, 12%). Across ages, the proportion of Black and Hispanic patients enrolled was 1%-10%. Compared to non-AYAs, AYAs in breast and colorectal cancer trials were less likely to be White and more likely to be Hispanic. Disease characteristics differed by age for selected trials. Two trials reported AYA-specific survival, with no significant differences observed by age. CONCLUSIONS: AYA accrual to Alliance trials was comparable to or exceeded population-based, age-specific prevalence estimates for most cancer types. Greater proportional representation of Hispanic and non-White patients among AYAs reflects US demographic trends. The small number of minority patients enrolled across ages underscores the persistent challenge of ensuring equitable access to trials, including for AYAs.

Hyper-Dependence on NHEJ Enables Synergy between DNA-PK Inhibitors and Low-Dose Doxorubicin in Leiomyosarcoma.

PURPOSE: Leiomyosarcoma (LMS) is an aggressive sarcoma for which standard chemotherapies achieve response rates under 30%. There are no effective targeted therapies against LMS. Most LMS are characterized by chromosomal instability (CIN), resulting in part from TP53 and RB1 co-inactivation and DNA damage repair defects. We sought to identify therapeutic targets that could exacerbate intrinsic CIN and DNA damage in LMS, inducing lethal genotoxicity. EXPERIMENTAL DESIGN: We performed clinical targeted sequencing in 287 LMS and genome-wide loss-of-function screens in 3 patient-derived LMS cell lines, to identify LMS-specific dependencies. We validated candidate targets by biochemical and cell-response assays in vitro and in seven mouse models. RESULTS: Clinical targeted sequencing revealed a high burden of somatic copy-number alterations (median fraction of the genome altered =0.62) and demonstrated homologous recombination deficiency signatures in 35% of LMS. Genome-wide short hairpin RNA screens demonstrated PRKDC (DNA-PKcs) and RPA2 essentiality, consistent with compensatory nonhomologous end joining (NHEJ) hyper-dependence. DNA-PK inhibitor combinations with unconventionally low-dose doxorubicin had synergistic activity in LMS in vitro models. Combination therapy with peposertib and low-dose doxorubicin (standard or liposomal formulations) inhibited growth of 5 of 7 LMS mouse models without toxicity. CONCLUSIONS: Combinations of DNA-PK inhibitors with unconventionally low, sensitizing, doxorubicin dosing showed synergistic effects in LMS in vitro and in vivo models, without discernable toxicity. These findings underscore the relevance of DNA damage repair alterations in LMS pathogenesis and identify dependence on NHEJ as a clinically actionable vulnerability in LMS.

Phase 1 study of cabozantinib in combination with topotecan-cyclophosphamide for patients with relapsed Ewing sarcoma or osteosarcoma.

PURPOSE: Phase 1 study assessing the safety and toxicity of cabozantinib in combination with topotecan and cyclophosphamide for relapsed osteosarcoma and Ewing sarcoma. METHODS: Oral cabozantinib (25 mg/m2 ) was administered daily for 21 (dose level 1) or 14 (dose level -1B) days. Topotecan (0.75 mg/m2 ) and cyclophosphamide (250 mg/m2 ) were administered intravenously (IV) on days 1-5. A modified 3+3 design based upon first cycle dose-limiting toxicities (DLT) was used for dose escalation. RESULTS: Twelve patients with a median age of 15 (12.9-33.2) years were enrolled (seven with Ewing sarcoma; five with osteosarcoma); all were evaluable for toxicity. At dose level 1, three of six patients developed first cycle DLT: grade 3 epistaxis, grade 3 transaminitis, and prolonged grade 2 thrombocytopenia. Six patients were enrolled on dose level -1B (interrupted cabozantinib, given days 8-21), with one first cycle DLT (grade 3 pneumothorax) observed. Of the 10 response evaluable patients, one had partial response (Ewing sarcoma), seven had stable disease, and two had progressive disease. CONCLUSIONS: The recommended phase 2 doses and schedules for this combination are topotecan 0.75 mg/m2 IV days 1-5, cyclophosphamide 250 mg/m2 IV days 1-5, and cabozantinib 25 mg/m2 days 8-21. Non-concomitant administration of cabozantinib with cytotoxic therapy in this population has acceptable toxicity, while allowing for potential disease control.

Developmental Considerations in How Defense Attorneys Employ Child Sexual Abuse and Rape Myths When Questioning Alleged Victims of Child Sexual Abuse.

Myths and misconceptions surrounding the nature of sexual assault play a role in shaping the perceptions of victims as credible and perpetrators as culpable. Defense attorneys often capitalize on myths in court as an element of their defense strategies. Researchers have established that myths about both rape generally, and child sexual abuse (CSA) specifically, appear with regularity in criminal trials of children who have made an allegation of CSA. Yet no work has systematically and quantitatively examined the impact of a child's age on the probability that attorneys will ask a myth-consistent question in criminal trials of CSA. In the current study, we examine 6,384 lines of questioning across 134 criminal trials of CSA to assess whether defense attorneys employ developmentally sensitive strategies when asking children questions that draw upon myths about sexual violence (CSA myths: disclosure myths, extent of harm, a child's positive relationship with their perpetrator, and the presence of witnesses; Rape myths: force and resistance, motives to lie, victim precipitation, and character issues). We found that attorneys did not vary their use of CSA myths by the age of the child. However, the probability that a child would receive a rape myth-consistent line of questioning, increased with a child's age. This work suggests that attorneys are, at times, strategic in their use of myths and employ these adult rape myths in ways that are plausible, purposeful, and likely impactful. The strategic use of these questions may acknowledge young children's limited development but may place too great a demand on older children's developmental capacities. Prosecutors should be prepared to counterquestion these myths in redirect examination.

Patient-reported outcomes and tolerability in patients receiving ripretinib versus sunitinib after treatment with imatinib in INTRIGUE, a phase 3, open-label study.

PURPOSE: In the INTRIGUE trial, ripretinib showed no significant difference versus sunitinib in progression-free survival for patients with advanced gastrointestinal stromal tumour (GIST) previously treated with imatinib. We compared the impact of these treatments on health-related quality of life (HRQoL). PATIENTS AND METHODS: Patients were randomised 1:1 to once-daily ripretinib 150 mg or once-daily sunitinib 50 mg (4 weeks on/2 weeks off). Patient-reported outcomes were assessed using the European Organisation for Research and Treatment of Cancer Quality of Life Questionnaire for Cancer-30 (EORTC QLQ-C30) questionnaire at day (D)1, and D29 of all cycles until treatment discontinuation. Change from baseline was calculated. Time without symptoms or toxicity (TWiST) was estimated as the mean number of days without progression, death, or grade ≥3 treatment-emergent adverse events per patient over 1 year of follow-up. RESULTS: Questionnaire completion at baseline was 88.1% (199/226) for ripretinib and 87.7% (199/227) for sunitinib and remained high for enrolled patients throughout treatment. Patients receiving sunitinib demonstrated within-cycle variation in self-reported HRQoL, corresponding to the on/off dosing regimen. Patients receiving ripretinib reported better HRQoL at D29 assessments than patients receiving sunitinib on all scales except constipation. HRQoL was similar between treatments at D1 assessments, following 2 weeks without treatment for sunitinib patients. TWiST was greater for ripretinib patients (173 versus 126 days). CONCLUSION: Patients receiving ripretinib experienced better HRQoL than patients receiving sunitinib during the dosing period and similar HRQoL to patients who had not received sunitinib for 2 weeks for all QLQ-C30 domains except constipation. Ripretinib may provide clinically meaningful benefit to patients with advanced GIST previously treated with imatinib.

Appellate Review of Child Sexual Abuse Convictions: The Importance of Character Evidence.

This study examined the role of character evidence and other issues in criminal appeals of child sexual abuse (CSA) convictions. Character evidence includes uncharged acts and character witnesses who testify to another's reputation or opinion and is offered to prove an individual's propensities. Examining 168 appellate court opinions reviewing CSA convictions between 2005 and 2015 in Maricopa County, Arizona, we found that when specific types of evidence were at issue, they were most often character evidence issues (49%). However, appellate courts virtually never reversed convictions (n = 5), and when defendants did obtain relief, the reduction in charges or in sentences was minor. Of the small number of opinions that were published (n = 4), all focused on character evidence, including the single case reviewed by the Arizona Supreme Court. However, close examination of the published cases suggested they effected only modest change.

Phase II Study of Olaparib and Temozolomide for Advanced Uterine Leiomyosarcoma (NCI Protocol 10250).

PURPOSE: Uterine leiomyosarcoma (uLMS) is an aggressive subtype of soft-tissue sarcoma with frequent metastatic relapse after curative surgery. Chemotherapy provides limited benefit for advanced disease. Multiomics profiling studies have identified homologous recombination deficiency in uLMS. In preclinical studies where olaparib and temozolomide provided modest activity, the combination was highly effective for inhibiting uLMS tumor growth. PATIENTS AND METHODS: NCI Protocol 10250 is a single-arm, open-label, multicenter, phase II study evaluating olaparib and temozolomide in advanced uLMS. Patients with progression on ≥1 prior line received temozolomide 75 mg/m2 orally once daily with olaparib 200 mg orally twice a day both on days 1-7 in 21-day cycles. The primary end point was the best objective response rate (ORR) within 6 months. A one-stage binomial design was used. If ≥5 of 22 responded, the treatment would be considered promising (93% power; α = .06). All patients underwent paired biopsies that were evaluated with whole-exome sequencing (WES)/RNAseq and a RAD51 foci formation assay. RESULTS: Twenty-two patients were evaluable. The median age was 55 years, and 59% had received three or more prior lines. Best ORR within 6 months was 23% (5 of 22). The overall ORR was 27% (6 of 22). The median progression-free survival (mPFS) was 6.9 months (95% CI, 5.4 months to not estimable). Hematologic toxicity was common (grade 3/4 neutropenia: 75%; thrombocytopenia: 32%) but manageable with dose modification. Five of 16 (31%) of tumors contained a deleterious homologous recombination gene alteration by WES, and 9 of 18 (50%) were homologous recombination-deficient by the RAD51 assay. In an exploratory analysis, mPFS was prolonged for patients with homologous recombination-deficient versus homologous recombination-proficient tumors (11.2 v 5.4 months, P = .05) by RAD51. CONCLUSION: Olaparib and temozolomide met the prespecified primary end point and provided meaningful clinical benefit in patients with advanced, pretreated uLMS.

Molecular Advances in the Treatment of Advanced Gastrointestinal Stromal Tumor.

Most gastrointestinal stromal tumors (GIST) are driven by activating mutations in Proto-oncogene c-KIT (KIT) or PDGFRA receptor tyrosine kinases (RTK). The emergence of effective therapies targeting these mutations has revolutionized the management of advanced GIST. However, following initiation of first-line imatinib, a tyrosine kinase inhibitor (TKI), nearly all patients will develop resistance within 2 years through the emergence of secondary resistance mutations in KIT, typically in the Adenosine Triphosphate (ATP)-binding site or activation loop of the kinase domain. Moreover, some patients have de novo resistance to imatinib, such as those with mutations in PDGFRA exon 18 or those without KIT or PDGFRA mutation. To target resistance, research efforts are primarily focused on developing next-generation inhibitors of KIT and/or PDGFRA, which can inhibit alternate receptor conformations or unique mutations, and compounds that impact complimentary pathogenic processes or epigenetic events. Here, we review the literature on the medical management of high-risk localized and advanced GIST and provide an update on clinical trial approaches to this disease.

A Phase I, Multicenter, Open-Label, First-in-Human Study of DS-6157a in Patients with Advanced Gastrointestinal Stromal Tumor.

PURPOSE: To evaluate DS-6157a, an antibody-drug conjugate targeting G protein-coupled receptor 20 (GPR20), in gastrointestinal stromal tumors (GIST). PATIENTS AND METHODS: In this phase I multicenter, open-label, multiple-dose study, patients with previously treated advanced GIST received intravenous DS-6157a on Day 1 of 21-day cycles, with a starting dose of 1.6 mg/kg. The primary objective evaluated the safety and tolerability of DS-6157a, while determining dose-limiting toxicity (DLT) and the MTD. Secondary objectives included plasma pharmacokinetics parameters, plasma antidrug antibodies (ADA), and efficacy. RESULTS: A total of 34 patients enrolled. DS-6157a was well tolerated, with DLTs in 4 patients (11.8%) at doses of 6.4 mg/kg, 9.6 mg/kg, and 12.8 mg/kg; the MTD was determined to be 6.4 mg/kg. Treatment-emergent adverse events (TEAE) grade ≥3 occurred in 17 patients (50.0%), including decreased platelet count (23.5%), anemia (20.6%), decreased neutrophil count (14.7%), and decreased white blood cell count (11.8%). Four patients (11.8%) experienced serious adverse events related to DS-6157a. Six patients died with 5 due to disease progression and 1 due to DS-6157a-related TEAE. Tumor shrinkage was observed in 7 patients (20.6%), and 1 patient (2.9%) achieved a partial response. Plasma concentrations and exposure of intact DS-6157a, DXd, and total anti-GPR20 antibody all demonstrated a dose-dependent profile. No treatment-emergent ADAs were observed. CONCLUSIONS: Targeting GPR20 with DS-6157a was tolerated in patients with advanced GIST with tumor shrinkage demonstrated in KIT/PDGFRA wild-type GIST. However, the study did not proceed further due to lower efficacy outcomes than anticipated.

Rates of and Factors Associated With Patient Withdrawal of Consent in Cancer Clinical Trials.

Importance: Patient withdrawal of consent from a cancer clinical trial is defined as a patient's volitional cessation of participation in all matters related to a trial. It can undermine the trial's purpose, make the original sample size and power calculations irrelevant, introduce bias between trial arms, and prolong the time to trial completion. Objective: To report rates of and baseline factors associated with withdrawal of consent among patients in cancer clinical trials. Design, Setting, and Participants: This multisite observational cohort study was conducted through the Alliance for Clinical Trials in Oncology. Patient withdrawal was defined as a patient's voluntary termination of consent to participate anytime during trial conduct. Baseline patient- and trial-based factors were investigated for their associations with patient withdrawal within the first 2 years using logistic regression models. All patients who participated in cancer therapeutic clinical trials conducted within the Alliance for Clinical Trials in Oncology from 2013 through 2019 were included. The data lock date was January 23, 2022. Main Outcomes and Measures: The percentage of patients who withdrew consent in 2 years and factors associated with withdrawal of consent. Results: A total of 11 993 patients (median age, 62 years; 67% female) from 58 trials were included. Within 2 years, 1060 patients (9%) withdrew from their respective trials. Two-year rates of withdrawal were 5.7%, 7.6%, 8.5%, 7.8%, 8.4%, 9.5%, and 9.8% for each of the respective years from 2013 through 2019. In multivariable analyses, Hispanic ethnicity (odds ratio [OR], 1.67; 95% CI, 1.30-2.15; P < .001), randomized design with placebo (OR, 1.64; 95% CI, 1.38-1.94; P < .001), and patient age 75 years and older (OR, 1.39; 95% CI, 1.12-1.72; P = .003) were associated with higher likelihood of withdrawal by 2 years. Use of radiation was associated with patient retention (OR, 0.68; 95% CI, 0.54-0.86; P = .001). Conclusions and Relevance: In this cohort study, rates of withdrawal of consent were less than 10% and appeared consistent over time. Factors that are associated with withdrawal of consent should be considered when designing trials and should be further studied to learn how they can be favorably modified.

National Cancer Institute Combination Therapy Platform Trial with Molecular Analysis for Therapy Choice (ComboMATCH).

Over the past decade, multiple trials, including the precision medicine trial National Cancer Institute-Molecular Analysis for Therapy Choice (NCI-MATCH, EAY131, NCT02465060) have sought to determine if treating cancer based on specific genomic alterations is effective, irrespective of the cancer histology. Although many therapies are now approved for the treatment of cancers harboring specific genomic alterations, most patients do not respond to therapies targeting a single alteration. Further, when antitumor responses do occur, they are often not durable due to the development of drug resistance. Therefore, there is a great need to identify rational combination therapies that may be more effective. To address this need, the NCI and National Clinical Trials Network have developed NCI-ComboMATCH, the successor to NCI-MATCH. Like the original trial, NCI-ComboMATCH is a signal-seeking study. The goal of ComboMATCH is to overcome drug resistance to single-agent therapy and/or utilize novel synergies to increase efficacy by developing genomically-directed combination therapies, supported by strong preclinical in vivo evidence. Although NCI-MATCH was mainly comprised of multiple single-arm studies, NCI-ComboMATCH tests combination therapy, evaluating both combination of targeted agents as well as combinations of targeted therapy with chemotherapy. Although NCI-MATCH was histology agnostic with selected tumor exclusions, ComboMATCH has histology-specific and histology-agnostic arms. Although NCI-MATCH consisted of single-arm studies, ComboMATCH utilizes single-arm as well as randomized designs. NCI-MATCH had a separate, parallel Pediatric MATCH trial, whereas ComboMATCH will include children within the same trial. We present rationale, scientific principles, study design, and logistics supporting the ComboMATCH study.

Randomized Phase II Trial of Sunitinib or Cediranib in Alveolar Soft Part Sarcoma.

PURPOSE: Alveolar soft part sarcoma (ASPS) is a rare, highly vascular tumor with few treatment options. We designed a phase II randomized trial to determine the activity and tolerability of single-agent cediranib or sunitinib in patients with advanced metastatic ASPS. PATIENTS AND METHODS: Patients 16 years of age and older were randomized to receive cediranib (30 mg) or sunitinib (37.5 mg) in 28-day cycles. Patients could cross over to the other treatment arm at disease progression. The primary endpoint was to measure the objective response rate (ORR) for each agent. Median progression-free survival (mPFS) for the two arms was also determined. RESULTS: Twenty-nine of 34 enrolled patients were evaluable for response. One patient on each of the initial two treatment arms had a partial response (ORR: 6.7% and 7.1% for cediranib and sunitinib, respectively). Twenty-four patients had a best response of stable disease (86.7% and 78.6% for cediranib and sunitinib, respectively). There were no significant differences in mPFS for the two treatment arms. Clinical benefit (i.e., objective response or stable disease for a minimum of four or six cycles of therapy) on the first-line tyrosine kinase inhibitor (TKI) therapy did not predict benefit on the second-line TKI. Both drugs were well tolerated. As of August 2021, 1 patient (unevaluable for ORR) remains on study. CONCLUSIONS: The study did not meet its endpoints for ORR. Although both TKIs provided clinical benefit, the outcomes may have been attenuated in patients who had progressed ≤6 months before enrollment, potentially accounting for the low response rates. See related commentary by Wilky and Maleddu, p. 1163.