Phase II Study of Erdafitinib in Patients With Tumors With Fibroblast Growth Factor Receptor Mutations or Fusions: Results From the NCI-MATCH ECOG-ACRIN Trial (EAY131) Subprotocol K2

PURPOSE

Subprotocol K2 (EAY131-K2) of the NCI-MATCH platform trial was an open-label, single-arm, phase II study designed to evaluate the antitumor efficacy of the oral FGFR1-4 inhibitor, erdafitinib, in patients with tumors harboring FGFR1-4 mutations or fusions.

METHODS

Central confirmation of tumor FGFR1-4 mutations or fusions was required for outcome analysis. Patients with urothelial carcinoma were excluded. Enrolled subjects received oral erdafitinib at a starting dose of 8 mg daily continuously until intolerable toxicity or disease progression. The primary end point was objective response rate (ORR) with key secondary end points of safety, progression-free survival (PFS), and overall survival (OS).

RESULTS

Thirty-five patients were enrolled, and 25 patients were included in the primary efficacy analysis as prespecified in the protocol. The median age was 61 years, and 52% of subjects had received ≥3 previous lines of therapy. The confirmed ORR was 16% (4 of 25 [90% CI, 5.7 to 33.0], P = .034 against the null rate of 5%). An additional seven patients experienced stable disease as best-confirmed response. Four patients had a prolonged PFS including two with recurrent WHO grade IV, IDH1-/2-wildtype glioblastoma. The median PFS and OS were 3.6 months and 11.0 months, respectively. Erdafitinib was manageable with no new safety signals.

CONCLUSION

This study met its primary end point in patients with several pretreated solid tumor types harboring FGFR1-3 mutations or fusions. These findings support advancement of erdafitinib for patients with fibroblast growth factor receptor-altered tumors outside of currently approved indications in a potentially tumor-agnostic manner.

Phase II Study of Osimertinib in Patients With Epidermal Growth Factor Receptor Mutations: Results From the NCI-MATCH ECOG-ACRIN (EAY131) Trial Subprotocol E

PURPOSE

The National Cancer Institute Molecular Analysis for Therapy Choice trial is a signal-finding genomically driven platform trial that assigns patients with any advanced refractory solid tumor, lymphoma, or myeloma to targeted therapies on the basis of next-generation sequencing results. Subprotocol E evaluated osimertinib, an epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor, in patients with EGFR mutations.

METHODS

Eligible patients had EGFR mutations (T790M or rare activating) and received osimertinib 80 mg once daily. Patients with lung cancer with EGFR T790M were excluded. The primary end point was objective response rate (ORR), and the secondary end points were 6-month progression-free survival (PFS), overall survival, and toxicity.

RESULTS

A total of 19 patients were enrolled: 17 were evaluable for toxicity and 13 for efficacy. The median age of the 13 included in the efficacy analysis was 63 years, 62% had Eastern Cooperative Oncology Group performance status 1, and 31% received >three previous systemic therapies. The most common tumor type was brain cancers (54%). The ORR was 15.4% (n = 2 of 13; 90% CI, 2.8 to 41.0) and 6-month PFS was 16.7% (90% CI, 0 to 34.4). The two confirmed RECIST responses were observed in a patient with neuroendocrine carcinoma not otherwise specified (EGFR exon 20 S768T and exon 18 G719C mutation) and a patient with low-grade epithelial carcinoma of the paranasal sinus (EGFR D770_N771insSVD). The most common (>20%) treatment-related adverse events were diarrhea, thrombocytopenia, and maculopapular rash.

CONCLUSION

In this pretreated cohort, osimertinib did not meet the prespecified end point threshold for efficacy, but responses were seen in a neuroendocrine carcinoma with an EGFR exon 20 S768T and exon 18 G719C mutation and an epithelial carcinoma with an EGFR D770_N771insSVD mutation. Osimertinib was well tolerated and had a safety profile consistent with previous studies.

Phase II Study of Erdafitinib in Patients With Tumors With FGFR Amplifications: Results From the NCI-MATCH ECOG-ACRIN Trial (EAY131) Subprotocol K1

PURPOSE

Despite fibroblast growth factor receptor (FGFR) inhibitors being approved in tumor types with select FGFR rearrangements or gene mutations, amplifications of FGFR represent the most common FGFR alteration across malignancies. Subprotocol K1 (EAY131-K1) of the National Cancer Institute-MATCH platform trial was designed to evaluate the antitumor efficacy of the oral FGFR1-4 inhibitor, erdafitinib, in patients with tumors harboring FGFR1-4 amplification.

METHODS

EAY131-K1 was an open-label, single-arm, phase II study with central confirmation of presence of FGFR1-4 amplification in tumors. Patients with urothelial carcinoma were excluded. Enrolled patients received oral erdafitinib at a starting dose of 8 mg once daily continuously with escalation to 9 mg once daily continuously, on the basis of predefined time point assessments of phosphate levels, until disease progression or intolerable toxicity. The primary end point was centrally assessed objective response rate (ORR), with key secondary end points being 6-month progression-free survival (PFS6), PFS, overall survival (OS), and safety.

RESULTS

Thirty-five patients were enrolled into this study with 18 included in the prespecified primary efficacy analysis. The median age of the 18 patients was 60 years, and 78% had received ≥3 previous lines of therapy. There were no confirmed responses to erdafitinib; however, five patients experienced stable disease (SD) as best response. One patient with an FGFR1-amplified breast cancer had a prolonged PFS >168 days (5.5 months). The median PFS was 1.7 months (90% CI, 1.1 to 1.8 months) and the median OS was 4.2 months (90% CI, 2.3 to 9.3 months). The estimated PFS6 rate was 13.8% (90% CI, 3.3 to 31.6). The majority of toxicities were grade 1 to 2 in nature, although there was one grade 5 treatment-related adverse event.

CONCLUSION

Erdafitinib did not meet its primary end point of efficacy as determined by ORR in treatment-refractory solid tumors harboring FGFR1-4 amplifications. Our findings support that rearrangements and gene mutations, but not amplifications, of FGFR remain the established FGFR alterations with approved indications for FGFR inhibition.

Trastuzumab and Pertuzumab in Patients with Non-Breast/Gastroesophageal HER2-Amplified Tumors: Results from the NCI-MATCH ECOG-ACRIN Trial (EAY131) Subprotocol J

PURPOSE

NCI-MATCH assigned patients with advanced cancer and progression on prior treatment, based on genomic alterations in pretreatment tumor tissue. Arm J (EAY131-J) evaluated the combination of trastuzumab/pertuzumab (HP) across HER2-amplified tumors.

PATIENTS AND METHODS

Eligible patients had high levels of HER2 amplification [copy number (CN) ≥7] detected by central next-generation sequencing (NGS) or through NCI-designated laboratories. Patients with breast/gastroesophageal adenocarcinoma and those who received prior HER2-directed therapy were excluded. Enrollment of patients with colorectal cancer was capped at 4 based on emerging data. Patients received HP IV Q3 weeks until progression or unacceptable toxicity. Primary endpoint was objective response rate (ORR); secondary endpoints included progression-free survival (PFS) and overall survival (OS).

RESULTS

Thirty-five patients were enrolled, with 25 included in the primary efficacy analysis (CN ≥7 confirmed by a central lab, median CN = 28). Median age was 66 (range, 31-80), and half of all patients had ≥3 prior therapies (range, 1-11). The confirmed ORR was 12% [3/25 partial responses (colorectal, cholangiocarcinoma, urothelial cancers), 90% confidence interval (CI) 3.4%-28.2%]. There was one additional partial response (urothelial cancer) in a patient with an unconfirmed ERBB2 copy number. Median PFS was 3.3 months (90% CI 2.0-4.1), and median OS 9.4 months (90% CI 5.0-18.9). Treatment-emergent adverse events were consistent with prior studies. There was no association between HER2 CN and response.

CONCLUSIONS

HP was active in a selection of HER2-amplified tumors (non-breast/gastroesophageal) but did not meet the predefined efficacy benchmark. Additional strategies targeting HER2 and potential resistance pathways are warranted, especially in rare tumors.

The New NCI Precision Medicine Trials

Basket, umbrella, and platform trial designs (master protocols) have emerged over the last decade to study precision medicine approaches in oncology. First-generation trials like NCI-MATCH (Molecular Analysis for Therapy Choice) have proven the principle that studying targeted therapies on a large scale is feasible both from the laboratory and clinical perspectives. However, single-agent targeted therapies have shown limited ability to control metastatic disease, despite careful matching of drug to target. As such, newer approaches employing combinations of targeted therapy, or targeted therapy with standard therapies, need to be considered. The NCI has recently embarked on three second-generation precision medicine trials to address this need: ComboMATCH, iMATCH, and myeloMATCH. The design of these trials and necessary infrastructure are discussed in the following perspective.

Tazemetostat for tumors harboring SMARCB1/SMARCA4 or EZH2 alterations: results from NCI-COG pediatric MATCH APEC1621C

BACKGROUND

National Cancer Institute-Children's Oncology Group Pediatric Molecular Analysis for Therapy Choice assigns patients aged 1-21 years with refractory solid tumors, brain tumors, lymphomas, and histiocytic disorders to phase II trials of molecularly targeted therapies based on detection of predefined genetic alterations. Patients whose tumors harbored EZH2 mutations or loss of SMARCB1 or SMARCA4 by immunohistochemistry were treated with EZH2 inhibitor tazemetostat.

METHODS

Patients received tazemetostat for 28-day cycles until disease progression or intolerable toxicity (max 26 cycles). The primary endpoint was objective response rate; secondary endpoints included progression-free survival and tolerability of tazemetostat.

RESULTS

Twenty patients (median age = 5 years) enrolled, all evaluable for response and toxicities. The most frequent diagnoses were atypical teratoid rhabdoid tumor (n = 8) and malignant rhabdoid tumor (n = 4). Actionable alterations consisted of SMARCB1 loss (n = 16), EZH2 mutation (n = 3), and SMARCA4 loss (n = 1). One objective response was observed in a patient with non-Langerhans cell histiocytosis with SMARCA4 loss (26 cycles, 1200 mg/m2/dose twice daily). Four patients with SMARCB1 loss had a best response of stable disease: epithelioid sarcoma (n = 2), atypical teratoid rhabdoid tumor (n = 1), and renal medullary carcinoma (n = 1). Six-month progression-free survival was 35% (95% confidence interval [CI] = 15.7% to 55.2%) and 6-month overall survival was 45% (95% CI = 23.1% to 64.7%). Treatment-related adverse events were consistent with prior tazemetostat reports.

CONCLUSIONS

Although tazemetostat did not meet its primary efficacy endpoint in this population of refractory pediatric tumors (objective response rate = 5%, 90% CI = 1% to 20%), 25% of patients with multiple histologic diagnoses experienced prolonged stable disease of 6 months and over (range = 9-26 cycles), suggesting a potential effect of tazemetostat on disease stabilization.

The NCI-MATCH trial: lessons for precision oncology

The NCI-MATCH (Molecular Analysis for Therapy Choice) trial ( NCT02465060 ) was launched in 2015 as a genomically driven, signal-seeking precision medicine platform trial-largely for patients with treatment-refractory, malignant solid tumors. Having completed in 2023, it remains one of the largest tumor-agnostic, precision oncology trials undertaken to date. Nearly 6,000 patients underwent screening and molecular testing, with a total of 1,593 patients (inclusive of continued accrual from standard next-generation sequencing) being assigned to one of 38 substudies. Each substudy was a phase 2 trial of a therapy matched to a genomic alteration, with a primary endpoint of objective tumor response by RECIST criteria. In this Perspective, we summarize the outcomes of the initial 27 substudies in NCI-MATCH, which met its signal-seeking objective with 7/27 positive substudies (25.9%). We discuss key aspects of the design and operational conduct of the trial, highlighting important lessons for future precision medicine studies.

Phase II Study of Selumetinib in Children and Young Adults With Tumors Harboring Activating Mitogen-Activated Protein Kinase Pathway Genetic Alterations: Arm E of the NCI-COG Pediatric MATCH Trial

PURPOSE

The NCI-COG Pediatric MATCH trial assigns patients age 1-21 years with relapsed or refractory solid tumors, lymphomas, and histiocytic disorders to phase II studies of molecularly targeted therapies on the basis of detection of predefined genetic alterations. Patients with tumors harboring mutations or fusions driving activation of the mitogen-activated protein kinase (MAPK) pathway were treated with the MEK inhibitor selumetinib.

METHODS

Patients received selumetinib twice daily for 28-day cycles until disease progression or intolerable toxicity. The primary end point was objective response rate; secondary end points included progression-free survival and tolerability of selumetinib.

RESULTS

Twenty patients (median age: 14 years) were treated. All were evaluable for response and toxicities. The most frequent diagnoses were high-grade glioma (HGG; n = 7) and rhabdomyosarcoma (n = 7). Twenty-one actionable mutations were detected: hotspot mutations in KRAS (n = 8), NRAS (n = 3), and HRAS (n = 1), inactivating mutations in NF1 (n = 7), and BRAF V600E (n = 2). No objective responses were observed. Three patients had a best response of stable disease including two patients with HGG (NF1 mutation, six cycles; KRAS mutation, 12 cycles). Six-month progression-free survival was 15% (95% CI, 4 to 34). Five patients (25%) experienced a grade 3 or higher adverse event that was possibly or probably attributable to study drug.

CONCLUSION

A national histology-agnostic molecular screening strategy was effective at identifying children and young adults eligible for treatment with selumetinib in the first Pediatric MATCH treatment arm to be completed. MEK inhibitors have demonstrated promising responses in some pediatric tumors (eg, low-grade glioma and plexiform neurofibroma). However, selumetinib in this cohort with treatment-refractory tumors harboring MAPK alterations demonstrated limited efficacy, indicating that pathway mutation status alone is insufficient to predict response to selumetinib monotherapy for pediatric cancers.

Phase II Study of Afatinib in Patients With Tumors With Human Epidermal Growth Factor Receptor 2-Activating Mutations: Results From the National Cancer Institute-Molecular Analysis for Therapy Choice ECOG-ACRIN Trial (EAY131) Subprotocol EAY131-B

PURPOSE

National Cancer Institute-Molecular Analysis for Therapy Choice is a multicohort trial that assigns patients with advanced cancers to targeted therapies on the basis of central tumor genomic testing. Arm B evaluated afatinib, an ErbB family tyrosine kinase inhibitor, in patients with ERBB2-activating mutations.

METHODS

Eligible patients had selected ERBB2 single-nucleotide variants or insertions/deletions detected by the National Cancer Institute-Molecular Analysis for Therapy Choice next-generation sequencing assay. Patients had performance status ≤ 1, left ventricular ejection fraction > 50%, grade ≤ 1 diarrhea, and no prior human epidermal growth factor receptor 2 (HER2) therapy. Patients received afatinib 40 mg once daily in 28-day cycles. The primary end point was objective response rate (ORR). Secondary end points were 6-month progression-free survival, overall survival, toxicity, and molecular correlates.

RESULTS

A total of 59 patients were assigned and 40 were enrolled. The median age was 62 years, 78% were female, 68% had performance status = 1, and 58% had received > 3 prior therapies. The confirmed ORR was 2.7% (n = 1 of 37; 90% CI, 0.14 to 12.2), and 6-month progression-free survival was 12.0% (90% CI, 5.6 to 25.8). A confirmed partial response occurred in a patient with adenocarcinoma of extra-mammary Paget disease of skin who progressed after cycle 6. Two unconfirmed partial responses were observed (low-grade serous gynecological tract and estrogen receptor-positive/HER2-negative immunohistochemistry breast ductal carcinoma). Of 12 patients with breast cancer, 1 additional patient with lobular carcinoma (estrogen receptor-positive/HER2 fluorescent in situ hybridization) had a 51% reduction in target lesions but progressed because of a new lesion at cycle 6. The most common (> 20%) treatment-related adverse events were diarrhea (68%), mucositis (43%), fatigue (40%), acneiform rash (30%), dehydration (27%), vomiting (27%), nausea (27%), anemia (27%), and anorexia (22%). Four patients (11%) discontinued because of adverse events.

CONCLUSION

Although afatinib did not meet the prespecified threshold for antitumor activity in this heavily pretreated cohort, the response in a rare tumor type is notable. The safety profile of afatinib was consistent with prior studies.

Molecular predictors of response among patients with MMRd tumors treated on NCI-MATCH Arm Z1D

2616

Background: On arm Z1D of the NCI-MATCH trial, the PD-1 inhibitor nivolumab was found to have activity among patients with mismatch repair-deficient (MMRd) tumors as defined by complete loss of MLH1 or MSH2 nuclear expression determined by immunohistochemistry, with 6-month progression free survival of 51%. We aimed to identify molecular predictors of response in this population. Methods: Among patients treated on NCI-MATCH Z1D, we evaluated genomic and tissue predictors of clinical benefit (CB), defined as patients with RECIST v1.1 complete or partial response or stable disease for ≥ 6months. WES files were processed and filtered using GATK best practices preceding TMB and MSI calculations according to MSI sensor score, a WES-based MSI rating system. Cutoffs were set to define TMB (TMB-Low: ≤10 mutation/Mb; TMB-High: >10) and MSI (MSS: ≤10% unstable loci; MSI-Low: 10 > x ≤ 20; MSI-High: >20). Multiplex immunofluorescence (mIF) used formalin-fixed paraffin-embedded slides stained using a BOND RX automated stainer. Expression analyses followed normalization in DEseq2's median of ratios method. Gene set enrichment analysis was conducted by “empirical phenotype-based permutation test.” Additional RNA, WES, and mIF comparisons used the Wilcoxon rank-sum test. Results: Among 36 patients accrued to NCI-MATCH Z1D with pretreatment correlative samples available, 7 were unevaluable for response, and 1 was misclassified as having an MMRd tumor. Of the remaining 28, 15 had CB (2 CR, 10 PR, 3 SD ≤ 6 months) and correlative data were available for 26 (WES), 27 (RNAseq), and between 10-20 for mIF based on the marker assessed. According to MSI-sensor score, 11 were MSI-high, 8 were MSI-low, and 7 were MSS. MSI-sensor status, but not TMB was associated with CB (p=0.037 and p=0.185, respectively). Similar results were seen when using CR+PR vs SD+PD evaluation. Using RNAseq gene set enrichment analyses, CB patients had increased expression of interferon alpha (p=0.01), interferon gamma (p=0.03), PI3K-AKT-mTOR (p=0.02), cytotoxicity (p=0.05) and antigen processing (p=0.01) gene sets, while hedgehog signaling genes were increased in non-CB patients (p=0.04). The ESTIMATE immune index and infiltration of CD4+/PD1+/Ki67+ cell populations as determined by mIF were nominally higher in patients with CB (p=0.051 and p=0.075). Conclusions: Among patients with MMRd tumors treated with PD-1 checkpoint blockade, correlative analyses demonstrate associations between CB and MSI-sensor score as well as biomarkers indicative of immune infiltration and antigen presentation. This suggests that these measures may help differentiate patient response in MSI tumors. Clinical trial information: NCT02465060.

Comparison of AYA versus non-AYA ovarian cancer genomic landscape in NCI-MATCH trial

e17617

Background: NCI-MATCH, a signal-finding precision medicine trial, centrally screened tumors from ̃6000 patients age > 18 with refractory/relapsed cancer using Oncomine Comprehensive Assay (OCA) targeted gene panel. Screened cohort included a subset of patients with ovarian cancer age 18-39 yrs, overlapping adolescent and young adult (AYA) range (NCI consensus definition: 15-39 yrs). Objective of this study was to compare tumor genomic features of AYA to non-AYA ovarian cancers. Methods: Patient clinicopathologic, demographic, and tumor mutation (SNVs, Indels, CNVs by central OCA) data from NCI-MATCH were available. Analyses were restricted to mutation profiles generated by OCA version 2 (OCA v2), which assessed 143 genes and was used for most samples. Proportions of cases with mutations in each gene were compared for AYA and non-AYA groups by 2-sided Fisher’s exact tests. For each gene, association between age (continuous independent variable) and presence of mutation (binary dependent variable) was assessed using logistic regression. Benjamini-Hochberg adjusted p-values were computed; false discovery rate (FDR) was controlled at 10%. Results: Data from 455 ovarian cancers (437 epithelial, 18 stromal), including 21 AYA and 434 non-AYA cases, were included in this analysis. Among the 28 genes most frequently (in > 6 patient tumors) mutated and altered, CTNNB1 was mutated in 9.5% of AYA patients compared to 0.9% in non-AYA (unadj. p=0.027) but failed to meet 10% FDR criterion (FDR-adj. p=0.7). KRAS mutation was more frequent in AYA than non-AYA but not significantly after adjustment (FDR-adj. p=0.7). Logistic regression results showed TP53 mutation was significantly associated with older age (FDR-adj. p<0.0001), and ATM mutation was borderline associated with younger age (FDR-adj. p=0.052). No other differences, including in clinically actionable mutations ( BRCA1/2, MSH2), were observed. Table displays selected results. Conclusions: This preliminary study shows that no genes were mutated in significantly different proportion between AYA and non-AYA groups, but modeling age as a continuous variable highlighted known association of TP53 mutation with older age and a trend towards association of ATM mutation with younger age. More comprehensive tumor mutation profiling and analyses of additional tumor types may reveal further insights into rare AYA cancers. [Table: see text]

Ulixertinib in patients with tumors with MAPK pathway alterations: Results from NCI-COG Pediatric MATCH trial Arm J (APEC1621J)

3009

Background: The NCI-Children’s Oncology Group (COG) Pediatric Molecular Analysis for Therapy Choice (MATCH) trial assigns patients age 1 to 21 years with relapsed or refractory solid tumors, lymphomas, and histiocytic disorders to phase 2 treatment arms of molecularly-targeted therapies based on genetic alterations detected in their tumor. Arm J evaluated the ERK1/2 inhibitor ulixertinib (BVD-523FB) in patients whose tumors harbored activating alterations in the MAPK pathway ( ARAF, BRAF, HRAS, KRAS, NRAS, MAPK1, MAP2K1, GNA11, GNAQ hotspot mutations; NF1inactivating mutations; BRAF fusions). Methods: As there were no prior pediatric data, ulixertinib was initially tested in a dose escalation cohort using a rolling 6 design to establish the recommended phase 2 dose (RP2D) before proceeding with enrollment to the phase 2 cohort. Ulixertinib was administered at 260 mg/m2/dose PO BID (dose level 1, DL1, n = 15) or 350 mg/m2/dose PO BID (dose level 2, DL2, n = 5). Patients were treated on continuous 28-day cycles for up to 2 years, until disease progression or intolerable toxicity; response assessment occurred every 2-3 cycles. The primary endpoint was objective response rate; secondary endpoints included safety/tolerability and progression-free survival (PFS). Results: Twenty patients (median age 12 years; range 5-20) were enrolled between November 2018 and March 2021. All patients were evaluable for response. High-grade glioma (HGG, n = 7) was most common, with CNS tumors comprising 55% (11/20) of diagnoses; all CNS tumors except one (HGG with KRAS and NF1 mutations) harbored BRAF fusions or V600 mutations. Rhabdomyosarcoma (n = 5) was the most frequent non-CNS diagnosis, with NRAS mutations detected in 4 tumors. DL1 was declared the RP2D after first-cycle dose limiting toxicities (DLTs) occurred in 1/6 DLT-evaluable patients at DL1 and 2/5 patients at DL2 in the dose escalation cohort. Any-cycle DLTs in 8 patients in the dose escalation and primary cohorts included fatigue, anorexia, rash, nausea, vomiting, diarrhea, dehydration, increased creatinine, hypoalbuminemia, hypernatremia, and hip fracture. No objective responses were observed. Six-month PFS was 37% (95% CI: 17%, 58%). Three patients with CNS tumors achieved stable disease > 6 months (HGG with BRAF fusion, 15 cycles; glioneuronal tumor with BRAF V600E, 9 cycles; low-grade glioma with BRAF fusion, 7 cycles). Analyses of correlative studies, including pharmacokinetics and circulating tumor DNA, are ongoing. Conclusions: The pediatric RP2D of ulixertinib was established as 260 mg/m2/dose PO BID. There were no objective responses in this cohort of children and young adults with treatment-refractory tumors with activating MAPK alterations. Clinical benefit of prolonged disease control was observed in 3 patients with BRAF-altered gliomas and glioneuronal tumors. Clinical trial information: NCT03698994.

Tazemetostat in patients with tumors with alterations in EZH2 or the SWI/SNF complex: Results from NCI-COG Pediatric MATCH trial Arm C (APEC1621C)

10009

Background: The NCI-Children’s Oncology Group (COG) Pediatric Molecular Analysis for Therapy Choice (MATCH) trial assigns patients, age 1-21 years, with relapsed or refractory solid tumors, lymphomas, and histiocytic disorders to phase 2 treatment arms based on genetic alterations detected in their tumor. Arm C evaluated the EZH2 inhibitor tazemetostat in patients whose tumors harbored EZH2 hotspot mutations or SMARCB1 or SMARCA4 loss by immunohistochemistry. Methods: Tazemetostat 1200 mg/m2/dose PO BID was administered to the first 13 patients; after study amendment due to second malignancy noted in the pediatric phase 1 trial, the dose for patients with non-CNS tumors was reduced to 520 mg/m2/dose PO BID. Patients were treated for 28-day cycles until PD or intolerable toxicity (max 26 cycles); response assessments occurred every 2-3 cycles. Primary and secondary endpoints were ORR and PFS, respectively. Results: Twenty eligible and evaluable patients (median age 5 years; range 1-21) were enrolled between Nov 2017 and Sept 2020. SMARCB1 loss was detected in 16/20 (80%) tumors: atypical teratoid rhabdoid tumor (ATRT, n = 8), malignant rhabdoid tumor (MRT, n = 4), epithelioid sarcoma (ES, n = 2), renal medullary carcinoma (RMC, n = 1) and hepatocellular carcinoma (HCC, n = 1). EZH2 mutations were identified in 3/20 (15%) tumors: Ewing sarcoma (n = 2), ependymoma (n = 1). One patient with Langerhans cell histiocytosis (LCH) had SMARCA4 loss. Centrally reviewed, one objective response (PR) was observed (LCH [SMARCA4], 26 cycles at 1200 mg/m2/dose BID). Five other patients had a best response of stable disease (ES [SMARCB1], 26 cycles, 520 mg/m2/dose BID; ATRT [SMARCB1], 13 cycles,1200 mg/m2/dose BID; RMC [SMARCB1], 12 cycles, 520 mg/m2/dose BID; ES [SMARCB1], 9 cycles,1200 mg/m2/dose BID; ATRT [SMARCB1], 6 cycles, 1200 mg/m2/dose BID). No other patients received > 2 cycles. Six-month PFS was 35% (95% CI 15.7%, 55.2%); OS was 45% (95% CI 23.1%, 64.7%). Treatment-related adverse events were consistent with AEs previously reported with tazemetostat, including anemia, thrombocytopenia, elevated LFTs, abdominal pain, dyspnea, infection, and intracranial hemorrhage. Three patients had bromide elevations. Conclusions: In this cohort of children with relapsed tumors harboring EZH2 mutations or loss of SMARCB1 or SMARCA4, tazemetostat did not produce significant objective responses (ORR: 5%, 90% CI 1%, 20%). However, we observed prolonged stable disease of > 6 months (range: 6-26 cycles) in 33% of patients across different histologic diagnoses, including two patients who received the full two years of study therapysuggesting a potential effect of tazemetostat on disease stabilization. Future studies will incorporate tazemetostat in combination with chemotherapy or immunologic agents for patients with these aggressive and difficult to treat tumors. Clinical trial information: NCT03213665.

Phase II study of vismodegib in patients with SMO or PTCH1 mutated tumors: Results from NCI-MATCH ECOG-ACRIN Trial (EAY131) Subprotocol T

3010

Background: NCI-MATCH (EAY131) is a platform trial enrolling patients (pts) with solid tumors, lymphomas, or multiple myeloma to targeted therapies based on matching genomic alterations (NCT02465060). Subprotocol Arm T evaluated vismodegib (GDC0449), a hedgehog signaling pathway inhibitor with anti-tumor activity in pts with tumors harboring PTCH1 and SMO mutations. Methods: Pts whose tumors had SMO or PTCH1 mutations were eligible; results were confirmed by NCI-MATCH central labs if possible. Pts received oral vismodegib (150 mg daily) for 4-week cycles until progression/toxicity. Tumor response was assessed every 2 cycles. Primary endpoint was ORR; secondary endpoints included PFS, 6-month PFS, OS, and predictive biomarkers. Cutaneous basal cell carcinomas were excluded. Results: Of 34 pts enrolled (6/20/16 – 9/22/20); 2 were ineligible and 1 did not start therapy. The 31 analyzable pts’ demographics were primary tumor sites/histology [gastrointestinal (n = 9), skin/soft tissue (n = 7), gynecologic (n = 5), lung (n = 4), unknown primary (n = 4), ductal breast (n = 1), meningioma (n = 1)]; median age 64 (range 19-81); 48.4% women; 61.3% (19/31) > 3 lines of prior therapy; 74% (23/31) > 1 co-occurring mutation [median 2 co-alterations (range 1-20)]. 8/31 > 4 co-occurring alterations. 9 pts had SMO mutant tumors (all SNVs); 5/9 had > 1 co-occurring gene alterations. 22 pts had PTCH1 alterations (7 SNVs and 15 indels); 18/22 pts had > 1 additional gene alteration. Of 31 analyzable pts, 22 were MATCH-confirmed (i.e. had central confirmation of tumor PTCH1/SMO mutations). MATCH-confirmed pts had ORR 9.1% (2/22) while all analyzable pts had ORR 6.5% (2/31). 2 PRs were seen in pts with a skin/soft tissue sarcoma ( PTCH) and a meningioma ( SMO) with a median duration of response 14 months. The 6-month PFS rate was similar in MATCH-confirmed and analyzable pts (22.4% and 23.2% respectively) and median PFS was identical at 1.8 months. Median OS was 9.1 months in MATCH-confirmed and 7.3 months in analyzable pts. Within analyzable SMO variants: 1 PR, 3 SD, 4 PD, and 1 unevaluable responses were documented. Within analyzable PTCH1 variants: 1 PR, 7 SD, 10 PD, and 4 unevaluable responses were seen. 4 pts (12.9%) discontinued therapy due to AE. Among 33 pts starting therapy, 18 (54.5%) had grade 1-2 toxicity, while 2 (6.1%) had grade 3 treatment-related toxicity. Most common toxicities: grade 1-2 fatigue (n = 11), anorexia (n = 8), weight loss (n = 7), alopecia (n = 7), and dysgeusia (n = 6). There were 4 on-study deaths, but none were treatment related. Conclusions: Although the primary endpoint was not reached, vismodegib was well-tolerated with mostly grade 1-2 toxicities and substantial responses were seen in patients with SMOPro641Ala and PTCHGlu947Ter alterations. Further study of the impact of concomitant molecular alterations may yield additional insights into vismodegib mechanisms of response. Clinical trial information: NCT02465060.

Phase II Study of Copanlisib in Patients With Tumors With PIK3CA Mutations: Results From the NCI-MATCH ECOG-ACRIN Trial (EAY131) Subprotocol Z1F

PURPOSE

Activating mutations in PIK3CA are observed across multiple tumor types. The NCI-MATCH (EAY131) is a tumor-agnostic platform trial that enrolls patients to targeted therapies on the basis of matching genomic alterations. Arm Z1F evaluated copanlisib, an α and δ isoform-specific phosphoinositide 3-kinase (PI3K) inhibitor, in patients with PIK3CA mutations (with or without PTEN loss).

PATIENTS AND METHODS

Patients received copanlisib (60 mg intravenous) once weekly on days 1, 8, and 15 in 28-day cycles until progression or toxicity. Patients with KRAS mutations, human epidermal growth factor receptor 2-positive breast cancers, and lymphomas were excluded. The primary end point was centrally assessed objective response rate (ORR); secondary end points included progression-free survival, 6-month progression-free survival, and overall survival.

RESULTS

Thirty-five patients were enrolled, and 25 patients were included in the primary efficacy analysis as prespecified in the Protocol. Multiple histologies were enrolled, with gynecologic (n = 6) and gastrointestinal (n = 6) being the most common. Sixty-eight percent of patients had ≥ 3 lines of prior therapy. The ORR was 16% (4 of 25, 90% CI, 6 to 33) with P = .0341 against a null rate of 5%. The most common reason for protocol discontinuation was disease progression (n = 17, 68%). Grade 3/4 toxicities observed were consistent with reported toxicities for PI3K pathway inhibition. Sixteen patients (53%) had grade 3 toxicities, and one patient (3%) had grade 4 toxicity (CTCAE v5.0). Most common toxicities include hyperglycemia (n = 19), fatigue (n = 12), diarrhea (n = 11), hypertension (n = 10), and nausea (n = 10).

CONCLUSION

The study met its primary end point with an ORR of 16% (P = .0341) with copanlisib showing clinical activity in select tumors with PIK3CA mutation in the refractory setting.

Actionable Tumor Alterations and Treatment Protocol Enrollment of Pediatric and Young Adult Patients With Refractory Cancers in the National Cancer Institute-Children's Oncology Group Pediatric MATCH Trial

PURPOSE

The National Cancer Institute-Children's Oncology Group Pediatric MATCH trial aimed to facilitate evaluation of molecular-targeted therapies in biomarker-selected cohorts of childhood and young adult patients with cancer by screening tumors for actionable alterations.

PATIENTS AND METHODS

Tumors from patients age 1-21 years with refractory solid tumors, lymphomas, or histiocytic disorders were subjected to cancer gene panel sequencing and limited immunohistochemistry to identify actionable alterations for assignment to phase II treatment arms. The rates of treatment arm assignment and enrollment were compared between clinical and demographic groups.

RESULTS

Testing was completed for 94.7% of tumors submitted. Actionable alterations were detected in 31.5% of the first 1,000 tumors screened, with treatment arm assignment and enrollment occurring in 28.4% and 13.1% of patients, respectively. Assignment rates varied by tumor histology and were higher for patients with CNS tumors or enrolled at Pediatric Early Phase Clinical Trials Network sites. A reported history of prior clinical molecular testing was associated with higher assignment and enrollment rates. Actionable alterations in the mitogen-activated protein kinase signaling pathway were most frequent (11.2%). The most common reasons provided for not enrolling on treatment arms were patients receiving other treatment or poor clinical status.

CONCLUSION

The Pediatric MATCH trial has proven the feasibility of a nationwide screening Protocol for identification of actionable genetic alterations and assignment of pediatric and young adult patients with refractory cancers to trials of molecularly targeted therapies. These data support the early use of tumor molecular screening for childhood patients with cancer whose tumors have not responded to standard treatments.

Abstract LBA003: Erdafitinib in patients with tumors harboring FGFR gene mutations or fusions: Results from the NCI-MATCH ECOG-ACRIN Trial (EAY131) Sub-protocol K2

Background: The NCI-MATCH precision medicine trial assigns patients (pts) with solid tumors, lymphoma, or multiple myeloma whose cancers have progressed on prior treatment to a targeted therapy based on genetic alterations identified in pre-treatment biopsies. Arm K2 (EAY131-K2) evaluated the pan-FGFR inhibitor erdafitinib (E) in pts with FGFR mutations or fusions. Patients and methods: Pts with bladder or urothelial cancers were excluded. Pts received E 8 mg PO daily (28-day cycle) until disease progression or unacceptable toxicity; dose reduction for toxicities was allowed; imaging was performed every 2 cycles. The primary endpoint was objective response rate (ORR); secondary endpoints included progression-free survival (PFS), 6-month PFS, and overall survival (OS). Results: A total of 35 pts were enrolled to this arm from 07/2018-07/2019; one was ineligible and one did not receive treatment. Nine distinct tumor histologies were represented, most common being pancreatobiliary (11), CNS (7) and gynecological tumors (5). 73% of pts were female, with median age of 59y (range 26-83y), 70% were Caucasian, and 61% of pts had received at least 3 prior therapies (range 0-22). Alterations in FGFR1, FGFR2 and FGFR3 were recorded in 6, 18, and 9 evaluable pts, respectively. 18 pt tumors had fusions and 15 had mutations in an FGFR gene. The confirmed ORR was 12% (90% CI 4%, 26%), with a median duration of response (DoR) of 7.3 months (mo), range 4.2-11.7 mo. Responses were seen in cholangiocarcinoma (2 pts), Brenner ovarian tumor and adenoid cystic carcinoma (1 pt each). Two (50%) of these 4 tumors harbored FGFR fusions and 2 FGFR mutations. 13 pts had stable disease (SD). Median PFS was 3.9 mo, and 6-mo PFS was 32.8% (90% CI 21.2%, 50.6%). Median OS was 11.0 mo. Of the 6 pts with intrahepatic cholangiocarcinoma, 2 had PR and 2 SD. The most frequent grade 3 treatment-related AEs were oral mucositis/pain (5 pts), paronychia, electrolyte disorders, and anemia/lymphopenia (2 pts each). There were no treatment-related grade 4-5 toxicities. Toxicities were reversible and manageable with E dose interruptions and/or dose reduction. Conclusions: In this pre-treated, mixed histology cohort with tumors harboring FGFR somatic alterations, E showed activity with durable responses and disease stabilizations outside of currently approved FDA indications, although the pre-specified criterion that the primary endpoint, ORR, be significantly greater than 16% was not reached. Toxicities were consistent with E safety profile. Responses were observed in tumors harboring FGFR fusions as well as in those with mutations of FGFR; further correlative analyses are planned.

Citation Format: Alain C Mita, Zihan Wei, Ingrid A Mayer, Heather Cheng, Edith P Mitchell, John J Wright, Percy Ivy, Robert J Gray, Victoria Wang, Lisa M McShane, Larry V Rubinstein, David R Patton, Mickey Williams, Stanley R Hamilton, Barbara A Conley, Carlos L Arteaga, Lyndsay N Harris, Peter J O'Dwyer, Alice P Chen, Keith T Flaherty. Erdafitinib in patients with tumors harboring FGFR gene mutations or fusions: Results from the NCI-MATCH ECOG-ACRIN Trial (EAY131) Sub-protocol K2 [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2021 Oct 7-10. Philadelphia (PA): AACR; Mol Cancer Ther 2021;20(12 Suppl):Abstract nr LBA003.

Differential Outcomes in Codon 12/13 and Codon 61 NRAS-Mutated Cancers in the Phase II NCI-MATCH Trial of Binimetinib in Patients with NRAS-Mutated Tumors

PURPOSE

Preclinical and clinical data suggest that downstream inhibition with an MEK inhibitor, such as binimetinib, might be efficacious for NRAS-mutated cancers.

PATIENTS AND METHODS

Patients enrolled in the NCI-MATCH trial master protocol underwent tumor biopsy and molecular profiling by targeted next-generation sequencing. Patients with NRAS-mutated tumors, except melanoma, were enrolled in subprotocol Z1A, a single-arm study evaluating binimetinib 45 mg twice daily. The primary endpoint was objective response rate (ORR). Secondary endpoints included progression-free survival (PFS) and overall survival (OS). A post hoc analysis examined the association of NRAS mutation type with outcome.

RESULTS

In total, 47 eligible patients with a refractory solid tumor harboring a codon 12, 13, or 61 NRAS mutation were treated. Observed toxicity was moderate, and 30% of patients discontinued treatment because of binimetinib-associated toxicity. The ORR was 2.1% (1/47 patients). A patient with malignant ameloblastoma harboring a codon 61 NRAS mutation achieved a durable partial response (PR). A patient with NRAS codon 61-mutated colorectal cancer had an unconfirmed PR, and two other patients with NRAS codon 61-mutated colorectal had stable disease for at least 12 months. In an exploratory analysis, patients with colorectal cancer bearing a NRAS codon 61 mutation (n = 8) had a significantly longer OS (P = 0.03) and PFS (P = 0.007) than those with codon 12 or 13 mutations (n = 16).

CONCLUSIONS

Single-agent binimetinib did not show promising efficacy in NRAS-mutated cancers. The observation of increased OS and PFS in patients with codon 61 NRAS-mutated colorectal cancer merits further investigation.

A phase 2 study of defactinib (VS-6063) in patients with NF2 altered tumors: Results from NCI-match (EAY131) subprotocol U

3087

Background: The NCI-MATCH trial assigns patients (pts) with solid tumors, lymphomas, or multiple myeloma to targeted therapies based on genetic alterations identified in tumor biopsies. Neurofibromatosis 2 (NF2)-inactivated tumors demonstrate increased sensitivity to FAK inhibition in preclinical models. Arm U evaluated the FAK inhibitor defactinib in pts with NF2 altered tumors. Methods: Patients found to harbor an inactivating NF2 mutation on NGS were assigned to the ARM U substudy MATCH. Defactinib 400 mg was given by mouth twice daily until progression or intolerable toxicity. The primary endpoint was objective response rate (ORR). Secondary endpoints included toxicity, progression-free survival (PFS), and 6-month PFS. Results: Of 5,548 cases with sufficient tissue for genomic analysis, 51 pts were found to have NF2 alterations (< 1% of the total analyzed). While NF2 alterations are known to occur more commonly in meningiomas and mesotheliomas, alterations were also detected in an array of other tumor types, including renal cell carcinomas and ovarian cancers. Thirty-five pts were ultimately enrolled; 33 patients were started on therapy, with 2 of those determined to be ineligible for outcome analysis. All pts had received at least one prior therapy, with 52% (16/31) having received 3 or more prior lines of therapy. Median follow-up was 35.9 months. ORR [90% CI] was 3% (1/31, [0.16, 14.86]), with the one partial response in a pt with choroid meningioma. Of the twelve pts whose best response was stable disease (39%, 12/31), 8 demonstrated some degree of tumor shrinkage (Table) with a disease control rate of 42% (13/31). Median PFS was 1.9 months for the 31 eligible pts who received study treatment, with median PFS of 9.3 months for the 9 patients who had a best response of stable disease or better. Six pts achieved a PFS of greater than 5.5 months. Among all treated pts (n=33), the most common treatment-related toxicities were fatigue (36%), nausea (33%), and hyperbilirubinemia (27%). There were no grade 4 or 5 toxicities; 27% of pts had grade 3 toxicities. No correlation could be made between clinical outcomes and tumor histology or specific NF2 genotype. Conclusions: Defactinib monotherapy had limited clinical activity in this cohort of previously treated patients with solid tumors exhibiting NF2 loss. Clinical trial information: NCT04439331. [Table: see text]

Selumetinib in patients with tumors with MAPK pathway alterations: Results from Arm E of the NCI-COG pediatric MATCH trial

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Background: The NCI-Children’s Oncology Group (COG) Pediatric Molecular Analysis for Therapy Choice (MATCH) trial assigns patients age 1 to 21 years with relapsed or refractory solid tumors, lymphomas, and histiocytic disorders to phase 2 treatment arms of molecularly-targeted therapies based on genetic alterations detected in their tumor. Arm E evaluated the MEK inhibitor selumetinib (ARRY-142886) in patients whose tumors harbored activating alterations in the MAPK pathway ( ARAF, BRAF, HRAS, KRAS, NRAS, MAP2K1, GNA11, GNAQ hotspot mutations; NF1 inactivating mutations; BRAF fusions). Methods: Patients received selumetinib 25 mg/m2/dose (max 75 mg/dose) PO BID for 28-day cycles until disease progression or intolerable toxicity with response assessments obtained every 2-3 cycles. The primary endpoint was objective response rate (ORR); secondary endpoints included progression-free survival (PFS). Patients with low grade glioma were excluded. Results: A total of 21 patients (median age 14 years; range 5-21) were enrolled between 10/2017 and 8/2019, with 20 patients evaluable for response. Diagnoses were high grade glioma (HGG; n = 8), rhabdomyosarcoma (n = 7), adenocarcinoma (n = 2), and one each of MPNST, endodermal sinus/yolk sac tumor, plexiform neurofibroma (PN), and neuroblastoma. MAPK pathway alterations detected consisted of inactivating NF1 mutations (n = 8), hotspot mutations in KRAS (n = 8), NRAS (n = 3), and HRAS (n = 1), and BRAF V600E (n = 2). No objective responses were observed. Three patients had a best response of stable disease (HGG with NF1 mutation, 6 cycles; HGG with KRAS mutation, 12 cycles; PN with NF1 mutation, 13 cycles prior to removal for dose-limiting toxicity). Six-month PFS was 15% (95% CI: 4%, 34%). Adverse events that were deemed possibly, probably, or definitely attributable to study drug included one case each of grade 3 uveitis, lymphopenia, and thromboembolic event; one grade 4 CPK elevation; and one grade 5 thromboembolic event. Conclusions: Selumetinib did not result in tumor regression in this cohort of children and young adults with treatment-refractory tumors with activating MAPK pathway alterations. Of note, two patients with HGG initially had stable disease, but ultimately progressed after 6 and 12 cycles, respectively. Selumetinib has previously demonstrated activity in low grade glioma and PN and is now FDA-approved for PN. The results of our study indicate that MAPK pathway mutation status alone is insufficient to predict response to selumetinib monotherapy. It is likely that selumetinib and other MEK inhibitors will require combination with targeted or cytotoxic agents for optimal efficacy in children with persistent or progressive cancers after front-line chemotherapy. Clinical trial information: NCT03213691. Clinical trial information: NCT03155620.

Factors impacting enrollment on NCI-COG Pediatric MATCH trial treatment protocols

10007

Background: The NCI-Children’s Oncology Group (COG) Pediatric Molecular Analysis for Therapy Choice (MATCH) trial assigns patients age 1 to 21 years with relapsed or refractory solid tumors, lymphomas, and histiocytic disorders to phase 2 treatment arms of molecularly-targeted therapies based on the genetic alterations detected in their tumor. Treatment arm assignments and enrollment decisions have now been made for 1000 study participants: we report here match and enrollment data and factors affecting treatment protocol enrollment. Methods: Patients enrolled in the Pediatric MATCH screening protocol were assigned to an open treatment protocol if an actionable mutation (aMOI) was detected by tumor DNA and RNA-based cancer gene panel sequencing. After a match, treatment protocol enrollment must occur within 8-12 weeks. Patient demographic data, reasons for not enrolling on treatment protocol (if applicable), and prior history of molecular testing were reported by study sites. The Fisher exact test was used to compare protocol enrollment rates between groups. Results: Results were analyzed for the first 1000 patients with testing completed (enrolled between July 2017 and October 2020). At least one tumor aMOI was detected in 310 (31%) patients and treatment protocol slots were available for 284 patients (28%). A total of 131 patients (46% of those matched) enrolled on a treatment arm. No difference in treatment protocol match or enrollment rate was observed for gender, race, or ethnicity. Both treatment protocol match rate (105/275, 38% vs 86/394, 22%) and enrollment rate (56/275, 20% vs 33/394, 8%) were significantly more frequent in patients with a reported history of prior molecular testing (p<0.0001). The most common reasons provided for not enrolling on a treatment protocol were: patient receiving other treatment (32% of responses), poor clinical status (16%), lack of measurable disease (11%), or ineligible diagnosis for that treatment arm (10%). Ineligibility due to history of excluded prior targeted therapy (6%) or inability to swallow capsules (4%) was less frequent. Conclusions: The rate of Pediatric MATCH treatment protocol enrollment has exceeded pre-study projections, due to more frequent actionable mutation detection and treatment assignment than anticipated (28% observed, 10% projected). This may in part reflect an increased number of targetable events in recurrent or refractory pediatric cancers. Correlative studies analyzing pre-treatment tumors from MATCH study patients are underway and will address this hypothesis. Prior history of molecular testing was associated with higher match and enrollment rate and poor clinical status was a common reason for not enrolling on a treatment protocol, suggesting that early molecular screening of children with solid malignancies may facilitate enrollment to biomarker-selected trials of targeted therapies. Clinical trial information: NCT03155620.

Phase II study of copanlisib in patients with tumors with PIK3CA mutations (PTEN loss allowed): NCI MATCH EAY131-Z1F

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Background: The NCI-MATCH (EAY131) is a platform trial that enrolls patients (pts) with solid tumors, lymphomas, or multiple myeloma to targeted therapies based on matching genomic alterations of interest (NCT02465060). Arm Z1F evaluated copanlisib, a highly selective, pan-Class 1 PI3K inhibitor with predominant activity against both the δ and α isoforms in pts with PIK3CA mutations. Methods: Pts received copanlisib (60 mg IV) on days 1, 8, and 15 in 28-day cycles until progression/toxicity. Tumor assessment was every 2 cycles. The primary endpoint was objective response rate (ORR); secondary endpoints were PFS, 6-month PFS, and predictive biomarkers. Pts with KRAS mutations, HER2+ve breast cancers, lymphomas were excluded. Results: 35 pts were enrolled (from 8/2/18 to 12/27/18), of which, 28 pts were available for analysis (7 patients, not eligible or did not start therapy). Multiple histologies were enrolled with gynecologic (n = 7), gastrointestinal (n = 6), and genitourinary (n = 5) the most common tumors. Median age 61 (range 42-78). 75% of pts had ≥ 3 lines of prior therapy. 54% of PIK3CA mutations were located in the helical domain, 32% in kinase domain and 14% in other domains. Twenty-six pts had co-occurring gene alterations (median 3; range 1-9), with 9 patients having 4 or more gene alterations. The ORR was 11% (3/28, 90% CI: 3%-25%). Partial responses were seen in uterine cancer, clear cell carcinoma of anterior abdominal wall, and liposarcoma. 6 pts had > 6 months of stable disease and clinical benefit rate was 32% (9/28). Two pts are still on treatment. The most common reason for protocol discontinuation was disease progression (n = 18, 69%). Thirty pts were included for toxicity analysis. Ten pts (33%) had grade 1 or 2 toxicities, 16 pts (53%) had grade 3 toxicities, and one patient (3%) had grade 4 toxicity (CTCAE v5.0). Most common toxicities include hyperglycemia (n = 19), fatigue (n = 11), hypertension (n = 10), diarrhea (n = 10), and nausea (n = 9). Total of 5 deaths were reported, none related to treatment. Conclusions: Copanlisib showed meaningful clinical activity across various tumors with PIK3CA mutation in the late-line refractory setting. Further study either alone or in combinations in select tumors is warranted. G3/4 toxicities observed were consistent with reported toxicities for PI3K pathway inhibition. Clinical trial information: NCT02465060 .

Nivolumab Is Effective in Mismatch Repair-Deficient Noncolorectal Cancers: Results From Arm Z1D-A Subprotocol of the NCI-MATCH (EAY131) Study

PURPOSE

The National Cancer Institute Molecular Analysis for Therapy Choice (NCI-MATCH) trial, the largest national precision oncology study to date (> 1,100 sites) of patients with relapsed or refractory malignancies, assigned patients to targeted therapy in parallel phase II studies based on tumor molecular alterations. The anti-programmed death receptor 1 inhibitor nivolumab previously showed activity in mismatch repair (MMR)-deficient colon cancer. We hypothesized that nivolumab would have activity in patients with MMR-deficient, noncolorectal tumors.

PATIENTS AND METHODS

Eligible patients with relapsed or refractory tumors, good end-organ function, and Eastern Cooperative Oncology Group performance status of ≤ 1 underwent tumor biopsy for centralized screening of molecular alterations. MMR deficiency was defined by complete loss of nuclear expression of MLH1 or MSH2 MMR gene products by immunohistochemistry (IHC). Patients with MMR-deficient colorectal cancer were excluded. Nivolumab, 3 mg/kg every 2 weeks (28-day cycles) and 480 mg every 4 weeks after cycle 4, was administered intravenously. Disease reassessment was performed every 2 cycles. The primary end point was RECIST 1.1 objective response rate (ORR).

RESULTS

Two percent of 4,902 screened patients had an MMR-deficient cancer by IHC. Forty-two evaluable patients were enrolled, with a median age of 60 years and a median of 3 prior therapies. The most common histologies were endometrioid endometrial adenocarcinoma (n = 13), prostate adenocarcinoma (n = 5), and uterine carcinosarcoma (n = 4). ORR was 36% (15 of 42 patients). An additional 21% of patients had stable disease. The estimated 6-, 12-, and 18-month progression-free survival rates were 51.3% (90% CI, 38.2% to 64.5%), 46.2% (90% CI, 33.1% to 59.3%), and 31.4% (90% CI, 18.7% to 44.2%), respectively. Median overall survival was 17.3 months. Toxicity was predominantly low grade.

CONCLUSION

A variety of refractory cancers (2.0% of those screened) had MMR deficiency as defined in NCI-MATCH. Nivolumab has promising activity in MMR-deficient noncolorectal cancers of a wide variety of histopathologic types.

Abstract A053: Prevalence of mismatch repair deficiency (dMMR) in the NCI Molecular Analysis for Therapy Choice (NCI-MATCH or EAY131) population

Introduction: NCI-MATCH (EAY131), a national signal-finding trial, assigns targeted treatments to patients (pts) with relapsed/refractory solid tumors, lymphomas and myelomas based on molecular abnormalities in tumors. We screened 4901 pts for dMMR, an eligibility criterion. Methods: Immunohistochemical expression (IHC) of MLH1 and MSH2 was performed at the CLIA-accredited MD Anderson Clinical IHC Laboratory. Loss of nuclear expression of MLH1 or MSH2 predicted microsatellite instability resulting from sporadic alterations or germline mutations. Assays were validated for FFPE tissue and used under an FDA abbreviated investigational device exemption. IHC was performed on 4 μm deparaffinized and rehydrated FFPE tissue sections. Antigen retrieval was performed at 100°C for 20 minutes with Tris-EDTA buffer solution, pH 6.0 & blocking of endogenous peroxidase with 3% peroxide for 5 minutes. Primary MLH1 antibody (Cell MarqueTM, clone G168-728) at 1:300 dilution and primary MSH2 antibody (Calbiochem®, clone FE11) at 1:100 dilution were applied. Primary antibody detection used a commercial polymer system (Bond Polymer Refine Detection, Leica) with stain development using incubation with DAB and DAB Enhancer (Leica). Loss of nuclear expression (required for dMMR eligibility): Complete loss of nuclear expression by tumor cells and retention of staining in non-neoplastic cells (internal control). Intact nuclear expression: Nuclear expression of any intensity within tumor cells. Cannot be determined: Insufficient specimen, technically inadequate IHC assay, or cytoplasmic staining without definite nuclear staining. Results: 4901 pts had MLH1/MSH2 IHC assay, of whom 37 had both MLH1 and MSH2 indeterminate. Of 4864 cases with valid MLH1/MSH2 results, 2% had dMMR (Table–histologies combined to fit allowed space). The most frequent dMMR was in the few thyroid/parathyroid tumors, followed by various gynecologic tumors. Conclusion: 2% of 4864 cases with valid MLH1/MSH2 results in NCI-MATCH had dMMR by IHC; prevalence varied across histologies. Many tumors lacking expression of MLH1 or MSH2 are not prominently associated with Lynch syndrome or frequent somatic dMMR. The NCI-MATCH screen for dMMR adds to information on the potential benefit of screening advanced/refractory tumor types for this abnormality as a standard practice for determining eligibility for PD-1 inhibitors. Pecent tumor categories lacking MLH1/MSH2 expressionHistologyLoss of nuclear MLH1 expressionLoss of nuclear MSH2 expression# screenedPercent of screenedGastrointestinal cancer29413252.5%Gynecological cancer28330110.3%Brain cancer02523.8%Sarcoma (various)601065.7%Thyroid/Parathyroid02366.7%Prostate071225.7%Breast715661.4%Neuroendocrine231922.6%Other303260.9%

Citation Format: Barbara A. Conley, Stanley R. Hamilton, Shuli Li, Robert J. Gray, David R. Patton, Peter J. O'Dwyer, Robert L. Comis, Jeffrey S. Abrams, Nilofer S. Azad, Michael J. Overman, Jonathan D. Schoenfeld, Paul M. Williams, James V. Tricoli, Elad Sharon, Howard Streicher, Lyndsay N. Harris, Alice P. Chen, Keith T. Flaherty. Prevalence of mismatch repair deficiency (dMMR) in the NCI Molecular Analysis for Therapy Choice (NCI-MATCH or EAY131) population [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2017 Oct 26-30; Philadelphia, PA. Philadelphia (PA): AACR; Mol Cancer Ther 2018;17(1 Suppl):Abstract nr A053.

A model of habitability within the Milky Way galaxy

We present a model of the galactic habitable zone (GHZ), described in terms of the spatial and temporal dimensions of the Galaxy that may favor the development of complex life. The Milky Way galaxy was modeled using a computational approach by populating stars and their planetary systems on an individual basis by employing Monte Carlo methods. We began with well-established properties of the disk of the Milky Way, such as the stellar number density distribution, the initial mass function, the star formation history, and the metallicity gradient as a function of radial position and time. We varied some of these properties and created four models to test the sensitivity of our assumptions. To assess habitability on the galactic scale, we modeled supernova rates, planet formation, and the time required for complex life to evolve. Our study has improved on other literature on the GHZ by populating stars on an individual basis and modeling Type II supernova (SNII) and Type Ia supernova (SNIa) sterilizations by selecting their progenitors from within this preexisting stellar population. Furthermore, we considered habitability on tidally locked and non-tidally locked planets separately and studied habitability as a function of height above and below the galactic midplane. In the model that most accurately reproduces the properties of the Galaxy, the results indicate that an individual SNIa is ∼5.6× more lethal than an individual SNII on average. In addition, we predict that ∼1.2% of all stars host a planet that may have been capable of supporting complex life at some point in the history of the Galaxy. Of those stars with a habitable planet, ∼75% of planets are predicted to be in a tidally locked configuration with their host star. The majority of these planets that may support complex life are found toward the inner Galaxy, distributed within, and significantly above and below, the galactic midplane.

Caltech Faint Galaxy Redshift Survey. XI. The Merger Rate to Redshift 1 from Kinematic Pairs

The rate of mass accumulation due to galaxy merging depends on the mass, density, and velocity distribution of galaxies in the near neighborhood of a host galaxy. The fractional luminosity in kinematic pairs combines all of these effects in a single estimator that is relatively insensitive to population evolution. Here we use a k-corrected and evolution-compensated volume-limited sample having an R-band absolute magnitude of Mk,eR</=-19.8+5logh mag drawing about 300 redshifts from the Caltech Faint Galaxy Redshift Survey and 3000 from the Canadian Network for Observational Cosmology field galaxy survey to measure the rate and redshift evolution of merging. The combined sample has an approximately constant comoving number and luminosity density from redshift 0.1 to 1.1 (OmegaM=0.2, OmegaLambda=0.8); hence, any merger evolution will be dominated by correlation and velocity evolution, not density evolution. We identify kinematic pairs with projected separations less than either 50 or 100 h-1 kpc and rest-frame velocity differences of less than 1000 km s-1. The fractional luminosity in pairs is modeled as fL&parl0;Deltav,rp,Mk,er&parr0;&parl0;1+z&parr0;mL, where &sqbl0;fL,mL&sqbr0; are &sqbl0;0.14+/-0.07,0+/-1.4&sqbr0; and &sqbl0;0.37+/-0.7,0.1+/-0.5&sqbr0; for rp</=50 and 100 h-1 kpc, respectively (OmegaM=0.2, OmegaLambda=0.8). The value of mL is about 0.6 larger if Lambda=0. To convert these redshift-space statistics to a merger rate, we use the data to derive a conversion factor to a physical space pair density, a merger probability, and a mean in-spiral time. The resulting mass accretion rate per galaxy (M1,M2>/=0.2M*) is 0.02+/-0.01&parl0;1+z&parr0;0.1+/-0.5M* Gyr-1. Present-day high-luminosity galaxies therefore have accreted approximately 0.15M* of their mass over the approximately 7 Gyr to redshift 1. Since merging is likely only weakly dependent on the host mass, the fractional effect, deltaM&solm0;M approximately 0.15M*&solm0;M, is dramatic for lower mass galaxies but is, on the average, effectively perturbative for galaxies above 1M*.

Conformational restriction of angiotensin II: cyclic analogues having high potency

Cyclic analogues of angiotensin II (AII) were synthesized by connecting the side chains of residues 3 and 5 via a disulfide bridge. Appropriate conformational constraints afforded an analogue, [Hcy3,5]AII, having high contractile activity (pD2 = 8.48 vs 8.81 for AII) and excellent binding affinity (IC50 = 2.1 nM vs 2.2 nM for AII). This type of cyclization was also used to prepare a highly potent AII antagonist, [Sar1,Hcy3,5,Ile8]AII (pA2 = 9.09 vs 9.17 for [Sar1, Ile8]AII; IC50 = 0.9 nM vs 1.9 nM for [Sar1,Ile8]AII). Model building suggests that this ring structure is consistent with a receptor-bound conformation having any of a variety of three-residue turns, including a gamma-turn. In contrast, the receptor-bound conformation of AII does not appear to accommodate a beta-turn or an alpha-helix which includes residues 3-5.

Structure-activity relationships for the carboxy-terminus truncated analogues of angiotension II, a new class of angiotensin II antagonists

A series of analogues of the recently reported angiotensin II (AII) antagonist [Sar1]AII-(1-7)-amide or des-Phe8[Sar1]AII (3) have been prepared by solid-phase synthesis and purified by reverse-phase liquid chromatography. The agonist and antagonist properties of these carboxy-truncated analogues of AII were determined in the isolated rabbit aorta assay. In the analogues tested, replacement of aspartic acid in position 1 by sarcosine was found necessary to produce significant antagonist activity. At position 7 of the des-Phe8 analogues, prolinamide could be replaced by proline without significant change in the biological activity. However, substitution of 7-prolinamide by either glycinamide or sarcosinamide provided inactive peptides. Methylation of the 4-tyrosine in [Sar1]AII-(1-7)-NH2 preserved the antagonist potency in isolated rabbit aorta. Deletion of the proline at position 7 resulted in inactive hexapeptides, both in the Asp1 and Sar1 series. However synthesis of the N,N-dimethyl amide at the N-terminus afforded hexapeptide [Sar1]AII-(1-6)-N(CH3)2 (10) with a pA2 value of 7.05. All the antagonistic peptides synthesized were fully reversible, competitive antagonists in vitro. These findings indicate that the structural requirements for receptor blockade by these C-truncated analogues are quite stringent with respect to the nature of the amino acid at positions 1 and 6/7. The analogues 2, 3, 7, 10, 11 (saralasin), and 12 (sarmesin) were tested in vivo in the anesthetized rat and were found to inhibit the AII pressor response. In addition, 3 inhibited angiotensin II stimulated aldosterone release from isolated rat adrenal zona glomerulosa cells and had no agonist activity by itself at the doses tested. Interestingly, analogue 3, when injected intracerebroventricularly in conscious rats, failed to antagonize the dipsogenic response to an angiotensin II icv injection and this reflects some heterogeneity in the AII receptor population. Peptide 3 is the first example of an antagonist that discriminates between peripheral and brain receptor subtypes.

A synthetic linear decapeptide binds to the atrial natriuretic peptide receptors and demonstrates cyclase activation and vasorelaxant activity

A linear decapeptide, [cyclohexylalanine 106]ANP-(105-114)NH2 (1), where ANP is atrial natriuretic peptide, was prepared by solid phase synthesis and purified by reverse-phase liquid chromatography. This novel peptide was found to bind to ANP receptors in rabbit lung membranes, to stimulate cGMP production in various tissues, and to fully relax precontracted rabbit aorta in a dose-dependent fashion. The potency of 1 in the various in vitro assays varies between one-twentieth and one-eightieth of the potency of the reference peptide, the 24-mer rat ANP-(103-126). The linear decapeptide 1, which encompasses amino acid residues from the rat ANP sequence (105-114), features a cyclohexylalanine residue instead of the phenylalanine 106 residue in the hormone sequence, a free sulfhydryl function at the N-terminal cysteine 105, and a carboxamide C terminus. Its disulfide dimer 6 was active in the rabbit aorta assay while the S-methyl cysteine 7 analogue was not active in the same assay at similar concentrations. The decapeptide 1 is of particular significance because it is the shortest analogue reported to date endowed with agonistic activity at the guanylate cyclase-coupled ANP receptor. In particular, it is interesting to compare its structure to the structures of other short linear analogues of ANP which are totally devoid of the ability to stimulate particulate guanylate cyclase activity.

Role of anemia in the pathogenesis of left ventricular hypertrophy in end-stage renal disease

Left ventricular (LV) hypertrophy is common in end-stage renal disease, yet the factors associated with its development are poorly understood. LV mass index was determined by echocardiography in 78 patients who had been treated by dialysis for at least 3 months. A significant relation was evident between anemia and LV hypertrophy. The mean LV mass index was 158 +/- 6 g/m2 (mean +/- standard error) in patients in the lowest quartile of serum hemoglobin and 140 +/- 10, 132 +/- 7 and 120 +/- 8 g/m2 in the second, third and uppermost quartiles, respectively (p = 0.005). This relation persisted after adjusting for systolic blood pressure, treatment mode and suspected coronary artery disease. Forty-eight patients had paired studies. In these, LV mass index increased as hemoglobin decreased (coefficient = -0.81 g/m2/g/liter, p less than 0.025). These data indicate that anemia contributes to the development of LV hypertrophy in patients with end-stage renal disease.

Analogues of atriopeptin(103-125)amide having high binding selectivity

Analogues of atriopeptin(103-125)amide were prepared having a disulfide bridge at positions different from that found in the natural product. Most of these conformationally perturbed peptides were found to bind selectively to one subclass of binding sites. Binding affinity to a class of specific binding sites that is not associated with any known biological activity (nonvasorelaxant or NVR binding sites) is unaffected or even modestly improved. Affinity for the receptor subclass that is associated with vasorelaxation (VR subclass) decreases in most examples. In several cases, binding to the VR subclass is below the limits of detection for the assay used here. The data demonstrate that binding of atrial peptides to VR receptors requires rigidly defined receptor/ligand interactions. In contrast, the NVR subclass of binding sites appears to tolerate changes in peptide structure quite well.

Identification of structural requirements for analogues of atrial natriuretic peptide (ANP) to discriminate between ANP receptor subtypes

The structure-activity relationships for affinity and selective binding of atrial natriuretic peptide (ANP) and analogues to guanylate cyclase coupled (CC) and non-cyclase coupled (NC) receptors in rabbit lung membranes are described. We have designed a series of peptides to try to identify the minimal sequence involved in specific recognition of each receptor subtype. The affinity of the peptides was determined from competitive binding experiments. Several peptides derived from the rat ANP sequence, e.g., des-[Phe106, Gly107, Ala115, Gln116]ANP-(103-125)NH2 (4), des-[Cys105,121]ANP-(104-126) (5), and [Acm-Cys105]ANP-(105-114)NH2 (9) have high affinity and selectivity for the noncoupled site. Peptide 4 was the most selective ligand with an affinity superior to that of ANP-(103-126). This compound does not displace the radiolabeled ligand from the guanylate cyclase coupled receptor at the highest concentration tested (100 nM). The structure-activity relationship for affinity and selectivity is discussed. Comparison of the peptide sequences suggests that the structural feature responsible for recognition of the NC site resides in a single sequence of seven contiguous amino acids from the cyclic core of the hormone. The corresponding heptapeptide retains affinity to the guanylate cyclase uncoupled binding site and is proposed to encompass the minimal sequence for specific recognition of the non-guanylate cyclase coupled ANP receptor.

Conformationally restricted analogues of atriopeptin(103-125)amide

Conformationally restricted analogues of atriopeptin(103-125)amide were prepared by synthesizing novel bicyclic peptides in which a second disulfide bridge linking residues 108 and 117 was introduced. These syntheses were shown to proceed with no significant scrambling of the disulfide bonds and demonstrated that structurally defined bicyclic analogues of atrial peptides could be easily prepared. The conformationally restrained analogues described here were found to be biologically active with potencies (EC50s) ranging from 0.05 to 3 microM. In addition, these bicyclic peptides (and many of the monocyclic precursors) were found to bind selectively to a class of specific tissue binding sites that have not been shown to be associated with any known second messenger system (NVR binding sites). Since affinity for the receptor class linked to vasorelaxation was negatively affected by the conformational restrictions described here, binding of atrial peptides to this class of receptors appears to have more specific conformational requirements than does binding to the NVR sites.

A linear analog of atrial natriuretic peptide (ANP) discriminates guanylate cyclase-coupled ANP receptors from non-coupled receptors

Atrial natriuretic peptide (ANP) contains a disulfide which is generally considered to be required for biological activity. A truncated linear ANP analog, des-Cys105,Cys121-ANP-(104-126) (referred to as analog I), that lacks the 2 cysteine residues of the parent peptide was synthesized. In competition binding studies using rabbit lung membranes, ANP-(103-126) and analog I displaced bound 125I-ANP-(103-126) from specific ANP binding sites 100 and 73%, respectively. The concentrations of ANP-(103-126) and analog I that produced 50% inhibition of radioligand binding to the membranes were 0.26 +/- 0.07 and 0.31 +/- 0.09 nM, respectively. Radioiodinated ANP-(103-126) and analog I were chemically cross-linked to binding sites on rabbit lung membranes, and the labeled membrane proteins were analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and autoradiography. 125I-Analog I specifically labeled a 65,000-dalton protein and a 135,000-dalton protein which, under reducing conditions, dissociated into 65,000-dalton subunits. In contrast, 125I-ANP-(103-126) labeled specifically a nonreducible 135,000-dalton protein, in addition to the 65,000-dalton species and the reducible 135,000-dalton species. ANP-(103-126) (100 nM) stimulated rabbit lung particulate guanylate cyclase activity, whereas analog I, at the same concentration, had no effect on cyclic GMP production and did not antagonize the effect of ANP-(103-126). From these observations, we conclude that analog I is a selective ligand which binds to approximately 73% of the total ANP binding sites present in rabbit lung membranes. Unlike ANP-(103-126), analog I does not bind to the remaining 27% of the binding sites and does not activate guanylate cyclase. Binding to the cyclase-linked ANP receptor correlates with the specific labeling by 125I-ANP-(103-126) of the nonreducible 135,000-dalton membrane protein.

Phosphorylation of high- and low-molecular-mass atrial natriuretic peptide analogs by cyclic AMP-dependent protein kinase

Synthetic high- and low-molecular-mass atrial peptides were phosphorylated in vitro by cyclic AMP-dependent protein kinase and [32P]ATP. From a series of atrial peptide analogs, it was deduced that the amino acid sequence, Arg101-Ser104 of atriopeptin was required for optimal phosphorylation. Phosphorylated AP(99-126) was less potent than the parent atriopeptin in vasorelaxant activity and receptor-binding properties. These results indicate that the presence of a phosphate group at the N-terminus of AP(99-126) decreases the interaction of the peptide with its receptor and, as a consequence, decreases bioactivity. These observations are in contrast to those of Rittenhouse et al. [(1986) J. Biol. Chem. 261, 7607-7610] who reported that phosphorylation of AP(101-126) enhanced the stimulation of Na/K/Cl cotransport in cultured vascular smooth muscle cells.

Specific receptors for atriopeptin III in rabbit lung

Binding studies revealed the presence of a single class of high affinity binding sites for atriopeptin III on rabbit lung membranes. An apparent dissociation constant (Kd) of 0.32 nM and a binding capacity of 166 fmol/mg protein was determined. Binding was time-dependent and saturable. The relative binding affinities of atrial peptide analogs correlated well with their potencies in eliciting relaxation of norepinephrine-contracted rabbit aorta strips. Unrelated peptide hormones did not compete for the atriopeptin binding site on rabbit lung membranes. The atrial peptide binding data are similar to those obtained for other tissues and indicate the presence of a physiologically relevant atrial peptide receptor in lung.

Computerized tomography, magnetic resonance imaging, and positron emission tomography in the study of brain trauma. Preliminary observations

Results of computerized tomography (CT), magnetic resonance imaging (MRI), positron emission tomography (PET), xenon-133 measurement of cerebral blood flow (CBF), and neuropsychological assessments are described in three head-injured patients. The patients were selected because they presented with intracranial hemorrhage diagnosed by CT. Two of the patients were studied acutely and again approximately 6 months later. In the acute stage, MRI was superior to CT in identifying the precise location and extent of intracranial hemorrhage and associated edema. Small subdural hematomas diagnosed on MRI were missed with CT scanning. The extent of apparent encephalomalacia in the chronic stages of injury was also better defined with MRI. Positron emission tomography showed disturbances of glucose metabolism that extended beyond the structural abnormalities demonstrated by MRI and CT; anterior temporal lobe dysfunction was particularly evident in all three patients. Regional CBF studies failed to detect a number of the abnormalities seen on MRI and CT, and even ignored the metabolic dysfunction evident on PET that should have been accompanied by changes in regional CBF. The neuropsychological studies localized frontal lesions, but did not reveal abnormalities attributable to the structural lesions and the reduced metabolism in the anterior temporal lobes.