Archival Tissue Research Articles

Clonal expansion of intra-epithelial T cells in breast cancer revealed by spatial transcriptomics.

The spatial distribution of tumor-infiltrating lymphocytes (TIL) predicts breast cancer outcome and response to systemic therapy, highlighting the importance of an intact tissue structure for characterizing tumors. Here, we present ST-FFPE, a spatial transcriptomics method for the analysis of formalin-fixed paraffin-embedded samples, which opens the possibility of interrogating archival tissue. The method involves extraction, exome capture and sequencing of RNA from different tumor compartments microdissected by laser-capture, and can be used to study the cellular composition of tumor microenvironment. Focusing on triple-negative breast cancer (TNBC), we characterized T cells, B cells, dendritic cells, fibroblasts and endothelial cells in both stromal and intra-epithelial compartments. We found a highly variable spatial distribution of immune cell subsets among tumors. This analysis revealed that the immune repertoires of intra-epithelial T and B cells were consistently less diverse and more clonal than those of stromal T and B cells. T-cell receptor (TCR) sequencing confirmed a reduced diversity and higher clonality of intra-epithelial T cells relative to the corresponding stromal T cells. Analysis of the top 10 dominant clonotypes in the two compartments showed a majority of shared but also some unique clonotypes both in stromal and intra-epithelial T cells. Hyperexpanded clonotypes were more abundant among intra-epithelial than stromal T cells. These findings validate the ST-FFPE method and suggest an accumulation of antigen-specific T cells within tumor core. Because ST-FFPE is applicable for analysis of previously collected tissue samples, it could be useful for rapid assessment of intratumoral cellular heterogeneity in multiple disease and treatment settings.

CLIMATE: Assessing the clinical utility of miR-371a-3p as a marker of residual disease in stage 1 testicular germ cell tumour (TGCT) following orchiectomy: ANZUP 1906.

TPS5100 Background: There is impetus to identify biomarkers in TGCT to help select those at high-risk of relapse following orchiectomy and target interventions to prevent over-treatment. miR-371 has been shown to reliably predict presence of active malignancy with higher accuracy than currently available biomarkers. More clinical evidence is required to ascertain its clinical utility as a marker of microscopic disease to guide treatment recommendations in stage 1 TGCT and other settings. Methods: CLIMATE ANZUP1906 (ACTRN12622000247774) is a prospective, single-arm, non-interventional cohort study recruiting adults with clinical stage 1 TGCT entering active surveillance. Eligible participants are recruited within six weeks of orchiectomy and are willing to undergo active surveillance in accordance with the Australian and New Zealand Urogenital and Prostate (ANZUP) Cancer Trials Group Surveillance Recommendations (or similar), without adjuvant treatment. Participants with metastases, non-testicular primaries, or history of contralateral TGCT are ineligible. Serum, plasma, and buffy coat samples are collected at consent and every three months until 24 months (and at relapse, if applicable). miR-371 will be assessed using established protocols. Clinical data, including treatment(s), surveillance, and relapses are captured in Australia’s national TGCT registry, iTestis. Archival tissue from diagnosis ± relapse is identified for future translational research. The primary endpoint for CLIMATE is 12-month relapse-free survival of miR-371 positive/negative groups. Key secondary endpoints include miR-371 during surveillance and at relapse, concordance between serum/plasma miR-371 and archival tissue, and health economic analyses. Prior studies suggest ~20% of post-orchidectomy miR-371 samples are positive. A sample size of 200 participants will result in 20 relapses, 160 non-relapses and 20 individuals lost to follow-up, and will permit description of the primary endpoint. Patient-level data from CLIMATE will contribute to a joint analysis of parallel trials evaluating miR-371 in this setting, COG AGCT1531 and SWOG1823. The first participant was recruited to CLIMATE in February 2022. 9/12 study sites in Australia and New Zealand have been activated and 47/200 (24%) have been enrolled. Recruitment is expected to take 36 months, followed by a further 24 months follow-up. Clinical trial information: ACTRN12622000247774 .

Phase II trial of combination pembrolizumab, olaparib, and temozolomide for patients with recurrent glioma.

TPS2087 Background: Diffuse gliomas are primary brain tumors characterized by substantial morbidity and mortality. Standard treatment includes maximal safe surgical resection followed by combination radiation and chemotherapy. Despite aggressive treatment, diffuse gliomas inevitably recur. Alkylating agents, and in particular temozolomide, play an important role in the treatment of gliomas, resulting in single-strand DNA breakages which require PARP activity for detection and repair. Gliomas with mutations in isocitrate dehydrogenase ( IDH) 1 or 2 have an accumulation of 2-hydroxyglutarate (2HG) which results in a BRCA-like state of homologous recombination deficiency (HRD). When PARP is inhibited in the setting of HRD, single-strand DNA damage progresses to double-strand breaks resulting in synthetic lethality. PARP inhibition has also been shown to increase mutational burden and neoantigen expression (“immune-priming”) and increases tumor-infiltrating lymphocytes and expression of PD-L1. Here, we present an ongoing clinical trial combining the checkpoint inhibitor pembrolizumab, the PARP inhibitor olaparib, and temozolomide for treatment of recurrent gliomas with HRD. Methods: This is an open-label, non-randomized phase II trial of combination pembrolizumab, olaparib, and temozolomide for patients with recurrent glioma. The main study cohort (A) will consist of 52 patients with recurrent enhancing grade 2 or 3 IDH-mutant gliomas. An exploratory cohort (B) will consist of 5 patients with recurrent IDH-wildtype gliomas and mutations associated HRD. Study intervention is administered in 21-day cycles and includes pembrolizumab (200mg IV q3 weeks day 1), olaparib (200mg bid orally days 8-14) and temozolomide (50mg/m2 orally days 8-14). The primary outcome is overall response rate (ORR) in cohort A. Secondary objectives include safety and toxicity of triplet therapy, overall and progression-free survival, and best radiographic response. Exploratory objectives will describe outcomes in the IDH-wildtype cohort and associate response to tumor markers obtained through archival tissue and cell free DNA of cerebrospinal fluid. The trial includes a 6-patient safety lead-in to assess tolerability of triplet therapy. Cohort A patients must have grade 2 or 3 IDH-mutant glioma without known CDKN2A/B loss. Patients in Cohort B must have IDH-wildtype glioma with an alternate deleterious mutation involved in homologous recombination. Additional inclusion criteria include age ≥ 18, ECOG 0-1, and glioma recurrent after prior therapy with measurable disease by RANO. Patients must be on a stable dose of corticosteroids not to exceed 2mg/day. There are no restrictions regarding number of recurrences or prior therapies if an appropriate washout has been completed. To date, seven of 57 patients have enrolled. The safety-lead in was completed without dose-limiting toxicities. Clinical trial information: NCT05188508 .

SARC041: A phase 3 randomized double-blind study of abemaciclib versus placebo in patients with advanced dedifferentiated liposarcoma.

TPS11587 Background: Recurrent or metastatic dedifferentiated liposarcoma (DDLS) remains a difficult disease to treat. Available agents such as doxorubicin, eribulin, trabectedin, ifosfamide, dacarbazine, or gemcitabine-based regimens are associated with low response rates and only modest improvements in progression free or overall survival. The oncogene CDK4 is ubiquitously amplified in this disease and represents a rational therapeutic target. In single-arm phase 2 studies, treatment with selective CDK4 inhibitors resulted in clinical benefit (12-week progression-free survival (PFS) of 57% with palbociclib and 74% with abemaciclib). We hypothesize that treatment with abemaciclib will improve PFS compared to placebo in patients with recurrent or metastatic DDLS. Methods: This is a phase 3 randomized double-blind study of abemaciclib versus placebo. Eligible patients have recurrent or metastatic dedifferentiated liposarcoma (purely well-differentiated liposarcoma excluded), progression of disease by RECIST 1.1 in the 6 months prior to study entry, any number of prior systemic therapies, and adequate organ function and performance status. Patients are stratified by number of prior lines of therapy (0 vs 1 or more) and randomized 1:1 between abemaciclib 200 mg PO twice a day and matching placebo. Patients are followed with scans every 6 weeks (every 12w after 36w) and those with progression of disease on placebo may cross over to open label abemaciclib. The primary endpoint is PFS. Target enrollment is 108 evaluable patients which provides 80% power with two-sided 10% significance level to detect a hazard ratio of 0.6. Secondary endpoints include response rate, PFS and response rate after crossover, and overall survival. Archival tissue will be collected to explore potential biomarkers. As of Feb 1, 2023, 43 patients have been accrued at 9 participating centers. Clinical trial information: NCT04967521 .

Luveltamab tazevibulin (STRO-002), an anti-folate receptor alpha (FolRα) antibody drug conjugate (ADC), safety and efficacy in a broad distribution of FolRα expression in patients with recurrent epithelial ovarian cancer (OC): Update of STRO-002-GM1 phase 1 dose expansion cohort.

5508 Background: Luveltamab tazevibulin (luvelta) is a novel FolRα-targeting ADC with a stable cleavable linker and a 3-aminophenyl hemiasterlin warhead (DAR of 4) that induces cytotoxic and immunologic cell death. Using site-specific conjugation technology, luvelta is designed to target a broad range of FolRα expressing OC. STRO-002-GM1 is a global phase 1 study evaluating luvelta in patients with relapsed OC. We provide updated data from the initial ovarian expansion cohort. Methods: The study enrolled advanced OC pts who had progressive platinum resistant (PROC) after 1-3 prior lines or platinum sensitive disease after 2-3 prior lines of platinum chemotherapy. Pts were randomized 1:1 to received luveltamab at 4.3 or 5.2 mg/kg given IV every 3 weeks until disease progression. Prophylactic corticosteroid eyedrops were not required/administered. FolRα expression was not required for study entry but was analyzed retrospectively in archival tissue using the FOLR1 IHC assay (Ventana Medical Systems). The scoring paradigm assessed percentage of cells with any intensity expression (TPS). TPS >25% was selected for further analysis. Results: 44 pts were enrolled (23 pts at 4.3 mg/kg and 21 pts at 5.2 mg/kg). For pts with a TPS >25% (n=35), the median prior lines of therapy was 2.5 (range 1-3), 69% had prior bevacizumab treatment, and 83% prior PARP inhibitor treatment. Investigator assessed efficacy data for pts with a TPS >25% are presented in the table. The most common grade ≥ 3 treatment emergent adverse events (TEAEs) included neutropenia (70.5%), arthralgia (18.2%), and anemia (13.6%). G3/4 neutropenia had a higher incidence at 5.2 mg/kg than 4.3 mg/kg (76% vs 65%); most notable for G4 neutropenia (52% vs 22%). 1 pt at each dose level had febrile neutropenia. TEAEs led to dose delay in 80% of pts with a higher incidence at 5.2 mg/kg (95% vs. 65%). TEAEs led to dose reduction in 61% of pts with a higher incidence at 5.2 mg/kg (76% vs. 48%). 1 pt had a G5 sepsis with G4 neutropenia. Neutropenia, arthralgia and anemia were managed with standard medical treatment and dose reductions. Conclusions: These dose expansion data confirm activity of luvelta at starting doses ranging from 4.3-5.2 mg/kg in recurrent OC with FolRα expression as low as TPS>25% and supports further clinical study in this population. The global phase 2/3 REFRaME registration study will evaluate luvelta in PROC pts with TPS >25%. Clinical trial information: NCT03748186 . [Table: see text]

Alliance A092104: A randomized phase 2/3 study of olaparib plus temozolomide versus investigator’s choice for the treatment of patients with advanced uterine leiomyosarcoma after progression on prior chemotherapy.

TPS11584 Background: Uterine leiomyosarcoma (uLMS) is an aggressive sarcoma subtype with frequent metastatic relapse. Advanced uLMS is treated with gemcitabine/docetaxel or anthracycline-based regimens. After failure of initial chemotherapy, remaining options provide limited benefit (trabectedin: objective response rate (ORR) 11%, median progression-free survival (mPFS) 4.0 months (mo); pazopanib: ORR 11%, mPFS 3.0 mo; dacarbazine: ORR 9%, mPFS 1.5 mo). 18-23% of uLMS harbor deleterious alterations in homologous recombination (HR) DNA repair genes. HR-deficient cancers are unable to effectively repair double-stranded DNA breaks and may be sensitive to poly ADP-ribose polymerase (PARP) inhibitor-based strategies. In preclinical studies, the combination of temozolomide (T), an alkylating agent, and olaparib (O), a PARP inhibitor, markedly suppressed proliferation of uLMS models. Among 22 uLMS patients with median 3 prior lines, O+T demonstrated mPFS 6.9 mo and ORR 27% (Ingham M. et al. ASCO 2021: #11506). In correlative analysis, alterations in HR genes including PALB2 and RAD51B or absence of RAD51 foci formation by a functional assay were observed in patients with prolonged PFS (Bose S. et al. ASCO 2022: #11509). Based on these results, we designed a randomized phase 2/3 study to further evaluate O+T in advanced, pretreated uLMS. Methods: Alliance for Clinical Trials in Oncology A092104 is a randomized, open-label phase 2/3 clinical trial of O+T versus investigator’s choice in advanced uLMS. Eligible patients have ECOG performance status ≤2, progression on ≥ 2 prior treatment lines and measurable disease. Patients are randomized 1:1 to receive T 75 mg/m2 orally daily + O 200 mg orally twice daily on days 1-7 in 21-day cycles (Arm 1) or investigator’s choice of trabectedin 1.5 mg/m2 over 24 hours every 21 days or pazopanib 400-600 mg orally daily (Arm 2). For phase 2, the primary endpoint is PFS. The design evaluates for an improvement in PFS from 4 mo to 8 mo, requires 70 patients, and yields 90% power and 1-sided alpha 0.10. If phase 2 is positive, phase 3 will enroll. For phase 3, the primary endpoint is overall survival (OS). The design evaluates for an improvement in OS from 13 mo to 23 mo, requires 165 patients (including 70 from phase 2) and yields 90% power with 1-sided alpha 0.025. Secondary endpoints include ORR, duration of response, safety and patient-reported outcomes. Archival tissue will be collected and evaluated with a RAD51 foci formation assay. Genomic sequencing results will be obtained where available. The study opened to accrual in 1/2023. Support: U10CA180821, U10CA180882, U24 CA196171; https://acknowledgments.alliancefound.org . Clinical trial information: NCT05633381 .

Anti–PD-1 combination regimen as first-line therapy in advanced biliary tract cancer and biomarker exploration: A retrospective study.

e16130 Background: Combination strategy of immune checkpoint inhibitors has potential to replace chemotherapy as a new first-line therapy for advanced biliary tract cancer (BTC). The aims of this study were to assess the efficacy of anti-PD-1 combination therapy in the first-line treatment of advanced BTC and to find reliable biomarkers associated with overall survival (OS). Methods: Clinical data from patients with advanced BTC who received chemotherapy or anti-PD-1 combination therapy as first-line were collected. The primary outcome of this study was OS. Blood test results were collected from patients who received anti-PD-1 in the week prior to treatment to calculate inflammation scores and analyze their relationship with OS. A total of eight scores were selected for analysis, including platelet-to-lymphocyte ratio (PLR), neutrophil-to-lymphocyte ratio (NLR), lymphocyte-to-C-reactive protein (CRP) ratio (LCR), lymphocyte-to-monocyte ratio (LMR), CRP to-albumin ratio (CAR), systemic immune-inflammation index (SII), prognostic nutritional index (PNI), and pan-immune-inflammation value (PIV). Moreover, archival tissues were collected for genetic testing and immunohistochemical staining to analyze genetic changes and the infiltration of immune cells in tumor tissues in relation to survival. Results: From January, 2018, to July, 2022, 64 patients were recruited: 11 were in the chemotherapy group, 21 were in the anti-PD-1 plus chemotherapy group, 21 were in the anti-PD-1 plus targeted therapy group and 11 were in the triple group (anti-PD-1 plus chemotherapy and targeted therapy). The median overall survival (mOS) was 7.9 months, 11.3 months, 12.8 months and 28.7 months, respectively. Compared to first-line chemotherapy, mOS was significantly prolonged in the triple group ( p= 0.031). The results of inflammation scores showed that patients with high LCR (≥0.4), high LMR (≥2.5), low CAR ( < 0.18), high PNI (≥44.3) or low PIV ( < 480.9) had significantly prolonged mOS compared to those with different scores ( p< 0.05). Genetic testing results suggested that patients with poor survival all had TP53 mutations and had higher levels of KRAS and ERBB2 mutations. Immunohistochemical results showed that a low FOXP3/CD8 ratio (≤0.27) was associated with prolonged OS ( p= 0.029). With CD4-low, CD8-high, CD56-positive, CD163-high, FOXP3-high and MPO-high in TME as one factor, we calculated immunoscore according to the number of factors. The high immunoscore group ( > 2) showed significantly superior OS ( p= 0.003). Conclusions: First-line anti-PD-1 antibody combination therapy was superior to chemotherapy, and triple therapy significantly improved survival. Peripheral blood immune-inflammation score, FOXP3/CD8 ratio and immunoscore have potential as biomarkers for predicting the efficacy of first-line anti-PD-1 antibody therapy in advanced BTC.

A phase 0 pharmacokinetic trigger trial of infigratinib in patients with recurrent high-grade glioma.

2051 Background: This Phase 0 trial evaluates tumor pharmacokinetic (PK) and pharmacodynamic (PD) responses of fibroblast growth factor receptor (FGFR) inhibitor, infigratinib, in participants with recurrent high-grade glioma carrying FGFR1 K656E or FGFR3 K650E mutation or FGFR3-TACC3 translocation. Patients with high unbound drug concentrations in the gadolinium-nonenhancing tumor region were graduated to a therapeutic regimen of infigratinib. Methods: Recurrent high-grade glioma patients received 7 days of infigratinib (125 mg QD) prior to planned resection at 7-9 hours following the last dose. Tumor tissue (enhancing and nonenhancing regions), cerebrospinal fluid (CSF), and plasma were collected. Total and unbound infigratinib concentrations were measured using validated LC-MS/MS methods. A PK ‘trigger’ determined eligibility for the therapeutic expansion phase and was defined as unbound [infigratinib] > 5-fold biochemical IC50 (i.e., 5 nM) in non-enhancing tumor. PD response was assessed by quantification of percentage of positive pERK, MIB-1, and Cleaved Caspase 3 cells in the surgical tissue compared to baseline archival/biopsy tissue. Patients with tumors exceeding the PK threshold for unbound drug concentration were eligible for expansion phase therapeutic dosing of infigratinib. Results: Seven patients were enrolled into the Phase 0 study with 3 patients who met the PK threshold continued to the expansion phase. In non-enhancing tumor region, the mean unbound concentration of infigratinib was 3.5 nM (n=7). The mean non-enhancing tumor-to-plasma coefficient for unbound drug (Kp,uu) was calculated to be 1.4. The suppression of pERK levels and MIB-1 levels was observed in 17% (1/6) and 67% (4/6) of the patients, respectively. At a median follow-up of 16.3 months [range: 2.8-18.7 months], the median progression-free survival (PFS) was 2.8 months (n=3). One patient remains on treatment. No grade 3+ toxicities were observed, and no adverse events resulted in discontinuation of therapy. Conclusions: Despite relatively high unbound tumor-to-plasma (Kp,uu) value, infigratinib achieves sub-optimal unbound drug concentration in the non-enhancing brain tumor tissue. Pharmacodynamic response with archival tissue as comparator did not reveal inhibition of pERK. Clinical trial information: NCT04424966 .

A pilot study of lenvatinib plus pembrolizumab in patients with advanced sarcoma.

11517 Background: New treatment options are needed for sarcomas. Lenvatinib (L) is an oral, multi-tyrosine kinase inhibitor with significant inhibitory activity against VEGF receptor (VEFGR) 1-3, FGF receptor (FGFR) 1-3, KIT, platelet-derived growth factor receptor (PDGFR) alpha/beta, and RET. Experimental models suggest that L can favorably alter the tumor immune environment, and the combination of L and pembrolizumab (P) has proven to be synergistic and effective across multiple solid tumor types, providing rationale for this study. Methods: This is a pilot study evaluating the efficacy of L and P in select sarcomas. Patients who had at least 1 prior regimen but ≤ 3 were enrolled into one of five cohorts (n = 10 each) A: leiomyosarcoma (LMS); B: undifferentiated pleomorphic sarcoma (UPS); C: angiosarcoma and epithelioid hemangioendothelioma (EHE); D: synovial sarcoma (SS) and malignant peripheral nerve sheath tumor (MPNST); and E: osteosarcoma (OS) and chondrosarcoma (CS). Patients were treated with an initial 2-week run-in of L 20 mg orally daily. Subsequently, P was administered at 200 mg IV every 21 days. The primary endpoint for each cohort was the best objective response rate (ORR) documented by RECIST v1.1 by 27 weeks. The combination was considered worthy of further study if 2 or more responses were observed in a cohort. Secondary endpoints included progression-free survival (PFS), overall survival, duration of response, and safety of the combination. Archival tissue and on-treatment biopsies were collected. Results: As of January 31st, 2023, cohorts A, D and E have completed accrual. The best response in the LMS cohort was stable disease (SD). In cohort D there were 3 partial responses (PR): 2 SS; 1 radiation associated high grade MPNST. In cohort E one of 6 patients with OS had a PR. To date, of the 6 patients with angiosarcoma, there was 1 PR in a patient with adrenal primary that occurred after the prespecified 27-week timepoint. One of 5 evaluable patients in Cohort B had a PR. Among the 44 patients evaluable for safety, most common AEs were hypertension (56.8%), diarrhea (45.5%), proteinuria (45.5%), fatigue (40.9%), headache (36.4%) and nausea (36.4%). Most common ≥ grade 3 AEs were hypertension (13.6%), dyspnea (6.8%), non-cardiac chest pain (6.8%), syncope (6.8%). Conclusions: A signal of activity was noted in this pilot study for patients with OS, MPNST, angiosarcoma and SS. In the LMS cohort, there were no responses, and PFS was poor. Enrollment to cohorts B and C is ongoing. Clinical trial information: NCT04784247 . [Table: see text]

Colon adjuvant chemotherapy based on evaluation of residual disease (CIRCULATE-US): NRG-GI008.

TPS3634 Background: Currently, there are no biomarkers validated prospectively in randomized studies for resected colon cancer (CC) to determine need for adjuvant chemotherapy (AC). However, circulating tumor DNA (ctDNA) represents a highly specific and sensitive approach (especially with serial monitoring) for identifying minimal/molecular residual disease (MRD) post-surgery in CC patients (pts), and may outperform traditional clinical and pathological features in prognosticating risk for recurrence. CC pts who do not have detectable ctDNA (ctDNA-) are at a much lower risk of recurrence and may be spared the toxicities associated with AC. Furthermore, for CC pts with detectable ctDNA (ctDNA+) who are at a very high risk of recurrence, the optimal AC regimen has not been established. We hypothesize that for pts whose CC has been resected, ctDNA status may be used to risk-stratify for making decisions about AC. Methods: In this prospective phase II/III trial, up to 1,912 pts with resected stage III A, B (all pts) and stage II, IIIC (ctDNA+ only) CC will be enrolled. Based on the post-operative ctDNA status using personalized and tumor-informed assay (SignateraTM, bespoke assay), those who are ctDNA- (Cohort A) will be randomized to immediate AC with fluoropyrimidine (FP) + oxaliplatin (Ox) for 3-6 mos per established guidelines vs. serial ctDNA monitoring. Patients who are ctDNA+ post-operatively or with serial monitoring (Cohort B) will be randomized to FP+Ox vs. more intensive AC with addition of irinotecan (I) for 6 mos. The primary endpoints for Cohort A are time to ctDNA+ status (phase II) and disease-free survival (DFS) (phase III) in the immediate vs. delayed AC arms. The primary endpoint for Cohort B is DFS in the FP+Ox vs FP+Ox+I arms for both phase II and phase III portions of the trial. Secondary endpoints include prevalence of detectable ctDNA post-operatively, time-to-event outcomes (overall survival and time to recurrence) by ctDNA status, and the assessment of compliance to adjuvant therapy. Biospecimens including archival tumor tissue, as well as post-operative plus serial matched/normal blood samples, will be collected for exploratory correlative research. Active enrollment across the NCTN started in June 2022. NCT#: NCT05174169. Support: U10-CA-180868, -180822; UG1CA-189867; Natera, Inc. Clinical trial information: NCT05174169 .

Lisavanbulin in patients with recurrent glioblastoma: Phase 2a results and a consolidated analysis of response-predictive biomarkers.

2044 Background: Lisavanbulin (BAL101553, prodrug of BAL27862) destabilizes microtubules and promotes tumor cell death by modulating the spindle assembly checkpoint. BAL27862 is a lipophilic small molecule shown in rodents to penetrate the brain, with antitumor activity in orthotopic glioblastoma (GBM) models. In the Phase 1 part of this study1 (NCT02490800), 2 of 5 patients with recurrent IDH-mutated G4 astrocytoma treated at active dose levels (15–30 mg/day) showed long-lasting objective responses and strong end-binding protein 1 (EB1) expression in GBM tissue by IHC. EB1 is a regulator protein on microtubules. Methods: The objective of the Phase 2 study was to investigate prospectively the response-predictive value of EB1, and to identify RNA-based response signatures in patients with recurrent GBM. A Simon’s two-stage design was used with an objective response rate (ORR) ≥ 2/9 required in Stage 1 to enable a final ORR ≥ 6/19. A prescreening program identified patients with EB1-positive archival GBM tissue. All patients received 25 mg oral lisavanbulin once daily. RNA-seq was performed on archival GBM tissues. Results: GBM tissue samples from 64 of 629 patients (10.2%) obtained from 13 sites in four countries were EB1-positive, and 18 of these patients received lisavanbulin. Of 9 patients with measurable disease evaluable for response in Stage 1, one patient had a partial response, and another had a 44% target lesion area reduction. Despite sustained activity in these patients, formal stage transition criteria were not met, and the study was closed. IHC testing for EB1 did not show sufficient enrichment for response, but it is thought that IDH status may play a role. In addition, RNA-seq analyses identified a five-gene signature that is distinct from expression patterns observed with EB1-IHC positivity, and predicts current responses irrespective of IDH status. This signature is characterized by homeobox gene downregulation, which may be implicated in the control of microtubule dynamics. Conclusions: This Phase 2a study supports previous study results that lisavanbulin is associated with durable responses and clinical benefit in a subset of patients with GBM. RNA-seq analyses of GBM samples suggest further evaluation of the lisavanbulin predictive response signature. 1Lopez et al, JCO 2019;37,15 suppl, 2025. Clinical trial information: NCT02490800 . [Table: see text]

Ultrasensitive detection and monitoring of central nervous system tumors from plasma using personalized whole-genome ctDNA profiling.

2064 Background: Patients with the central nervous system (CNS) tumors are largely followed up by imaging. Current plasma-based liquid biopsy techniques have limited utility in neuro-oncology due to a low circulating cell-free tumor DNA (ctDNA) burden, blood-brain barrier, and low number of mutations in coding regions. Whole genome sequencing (WGS)-derived patient specific mutational signature from a matched tumor-normal WGS can provide a personalized, highly sensitive and specific approach to detect mutations in ctDNA and provide blood-based monitoring in brain tumor patients. Furthermore, it can be performed on lower amount of peripheral blood since WGS requires less sequencing depth compared to targeted ctDNA panels. Methods: We have profiled a cohort of 28 extra- and intra-axial adult and pediatric brain tumors including adult and pediatric low- and high-grade glioma (9), meningiomas (11), medulloblastomas (5), ependymomas (2), neurocytoma (1). Tumor DNA was extracted from archival pathology tissue, normal DNA from unsorted white blood cells, and ctDNA from 1-2 mL of post-surgery plasma. WGS was performed with 40x coverage for Tumor-Normal DNA and 20x for ctDNA. Using WGS of matched Tumor-Normal and plasma samples, we derived a personalized mutational pattern using SNVs, indels, and copy numbers for quantification and ultra-sensitive detection of ctDNA in plasma samples. An AI-based error suppression model was implemented to filter out the noise in the cell-free DNA (cfDNA) while the personalized mutational signature was used to detect the ctDNA in the cfDNA and to amplify the somatic signal to determine the Tumor Fraction at the time of diagnosis, during the therapy or surveillance period. The ctDNA Tumor Fraction (TF) was compared to the clinical status and MRI-based imaging. Results: All subtypes of brain tumors contained enough mutations to derive personalized mutational signatures. Most mutations were distributed in the noncoding DNA. TF correlated with clinical status and with the disease course on imaging at given time points reaching a 10-4 minimal residual disease detection sensitivity. We were able to detect ctDNA across all WHO grades ranging from WHO 1 meningioma to WHO 4 glioblastoma and medulloblastoma. Furthermore, we were able to detect tumor-specific copy number aberrations such as MYCN amplification in plasma samples and mutational signatures. Conclusions: Here we demonstrate that patient-specific WGS tumor signature in ctDNA from plasma can be used for sensitive monitoring of adults and children with primary low- and high-grade CNS tumors.

A phase 1a dose-escalation study of PY159, a monoclonal antibody targeting TREM1 (triggering receptor expressed on myeloid cells 1).

2523 Background: This study aimed to characterize the safety of PY159 (an agonist antibody to TREM1 that reprograms immunosuppressive intratumoral myeloid cells) as a single agent and in combination with pembrolizumab in subjects with advanced refractory solid tumors, including subjects refractory to immune checkpoint inhibitors. Methods: Two strata were evaluated, PY159 as a single agent and in combination with pembrolizumab, using an accelerated 3+3 dose escalation study design. Dosing was intravenous once every 3 weeks. Disease assessment by RECIST 1.1 was performed every 6 weeks. The single-agent stratum included 7 dose levels of PY159 (range, 0.01–10 mg/kg). The combination stratum included 4 dose levels of PY159 (range, 0.3–10 mg/kg). Pharmacokinetics were evaluated at specified time points. Archival tumor tissue was analyzed for TREM1 expression by immunohistochemistry. Based on preclinical immunohistochemistry data, HR+ HER2– and triple-negative breast cancer, gastric cancer, pancreatic cancer, head and neck cancer, non-small cell lung cancer, and gynecologic cancers were studied. Results: Thirty-seven subjects (median age 65 years; range 29–86 years; 22 female and 15 male) with an ECOG PS <2 were enrolled and all but 5 were RECIST-evaluable (3 withdrew consent, 1 sustained a TEAE, and 1 had a DLT, an asymptomatic grade-3 transaminitis). Twenty subjects received single-agent PY159 and 17 received PY159 in combination with pembrolizumab. Four subjects experienced a grade-3 TRAE, 14 a low-grade immune-related reaction, 18 an SAE (related in 2), and 14 an immune-related adverse event (arthralgias). There were no SUSARs. Five subjects sustained high-grade TRAE resulting in discontinuation. TREM1 levels in the tumors ranged from 0 to 15%. Pharmacokinetic parameters were linear beyond the 0.3 mg/kg dose, dose proportional with a half-life of 8–9 days, and unaffected by pembrolizumab. Radiographic response included 2 partial responses (1 each in an ovarian and pancreatic cancer subject) and stable disease in 9 subjects, ranging from 12 to 96+ weeks. Two subjects continue receiving PY159. Conclusions: PY159 was well tolerated, with an acceptable safety profile, as a single agent and in combination with pembrolizumab. A dose for expansion was derived and enrollment of subjects with 7 prespecified cancers is ongoing. Clinical trial information: NCT04682431 .

A randomized phase II study comparing single-agent olaparib, single-agent cediranib, and the combinations of cediranib/olaparib, olaparib/durvalumab (MEDI4736), cediranib/durvalumab (MEDI4736), and olaparib/AZD5363 (capivasertib) in women with recurrent, persistent, or metastatic endometrial cancer.

TPS5629 Background: Identifying new approaches for the treatment of advanced endometrial cancer (EC) is a priority. A platform study design allows for a faster investigation of novel drug combinations. NRG-GY012 is an ongoing platform study investigating drug combinations with the PARP inhibitor olaparib (O) and the anti-angiogenic agent cediranib (C). Results from the first set of arms established improved PFS for combination cediranib/olaparib over C alone, but did not meet its prespecified statistical significance. In this second set of arms, based on preclinical data, we are investigating the combination of O with an AKT inhibitor (capivasertib), O with durvalumab and C with durvalumab compared to the reference arm of C alone. Methods: This is a multicenter randomized four arm study for patients with recurrent, metastatic or persistent EC. Patients are randomized 1:1:1:1 to cediranib PO 30 mg Daily; olaparib 300 mg PO BID and capivasertib 400mg 4 day on/3 off schedule; olaparib 300 mg PO BID and durvalumab 1500mg q28 days; or the combination of cediranib 20 mg PO Daily 5 days on/2 days and durvalumab 1500mg q28. All treatment cycles are 28 days. Primary endpoint is progression free survival (PFS). The study is powered to detect a doubling in median PFS from 3.6 (based on cediranib alone) to 7.2 months with 90% power, using a one-sided test with α = 0.05 per comparison. Forty patients will be enrolled per arm, with an interim futility analysis planned at 50% information time. Eligibility includes endometroid, serous, and mixed histology EC; at least 1 prior line of chemotherapy (no more than 2 lines for metastatic disease), prior endocrine or immunotherapy alone is allowed; prior treatment with lenvatinib and pembrolizumab is excluded. Archival tumor tissue and blood samples are being collected for translational studies. The study is open across the NRG network; 76 of a planned 168 patients are enrolled to date. Safety analysis at the time of 36 patients enrolled did not demonstrate any new safety signals and the study was approved to continue enrollment. Clinical trial information: NCT03660826 .

A phase 2 study of the WEE1 inhibitor AZD1775 in SETD2-deficient advanced solid tumor malignancies.

3104 Background: AZD1775 is an inhibitor of the WEE1 kinase, leading to loss of genome integrity. Pathogenic SETD2 mutations lead to genome-wide loss of histone H3K36 trimethylation (H3K36me3) and hypersensitivity to WEE1 inhibition with a synthetic lethal effect. AZD1775 was studied in 2 cohorts of patients: A) Patients (pts) with locally advanced/metastatic solid tumor malignancy other than clear cell renal cell carcinoma (ccRCC) and B) pts with locally advanced/metastatic ccRCC. Methods: Eligible pts had a locally advanced/metastatic cancer with progression on ≥ 1 prior systemic therapy (including prior tyrosine kinase inhibitor or checkpoint inhibitor for cohort B), and a pathogenic SETD2 mutation by CLIA-certified next generation sequencing panel. Pts received AZD1775 at a starting dose of 300 mg PO daily on days 1-5, 8-12 of each 21-day cycle. The primary objective was to determine the objective response rate (ORR) by RECIST 1.1 criteria in each cohort. Planned sample size was 9 pts in each cohort in stage 1 of a Simon two-stage design. Secondary objectives were to determine the clinical benefit rate (CBR) (defined as partial response or stable disease [SD] > 4 months), duration of response (DOR), and safety. Correlative assays include the evaluation of H3K36me3 mark by immunohistochemistry (IHC) in archival tumor tissue. Results: Between 05/2019 and 10/2021, 18 pts whose tumor harbored a pathogenic mutation in SETD2 were enrolled (9/cohort). The median age was 60 years (range 45 – 74), ECOG PS 0 in 8 (44.4%). One patient remains on treatment; 17 have discontinued (disease progression, n = 9; adverse event, n = 4; patient withdrawal, n = 2; patient death, n = 1). The median duration of treatment was 1.89 months (range 0.75 – 13.5). There were no confirmed objective responses and therefore enrollment was halted following accrual to stage 1. Tumor regression of any magnitude was observed in 5/17 (29%) evaluable pts. Stable disease was the best overall response in 10/17 (59%) evaluable pts, including 3 pts with SD for > 4 months. One patient with RCC remains on treatment with SD for 14+ months duration. The most common adverse events of any grade were nausea (59%), anemia (41%), diarrhea (41%), and neutropenia (41%). Twelve pts (67%) experienced a Grade ≥ 3 adverse event. Evaluation of H3K36me3 using IHC as an exploratory biomarker is underway. Conclusions: AZD1775 given as monotherapy failed to achieve an objective response in SETD2-altered RCC and other solid tumor malignancies. However, a subset of pts derived clinical benefit as manifested by tumor regressions and/or durable stable disease. Evaluation of AZD1775 in combination with other DNA damage-inducing agents that cause replication stress may be warranted, potentially with the integration of the H3K36me3 mark as a biomarker for patient selection. Clinical trial information: NCT03284385 .

Reversion of RAS mutations in metastatic colorectal cancer in the CCTG CO.26 clinical trial.

3567 Background: RAS mutations in metastatic colorectal cancer (mCRC) drive resistance to anti-EGFR antibodies. It is unclear if RAS mutations are ever clonally lost, potentially uncovering a new therapeutic option for patients over time. Methods: We examined the temporal evolution of RAS mutation status among patients enrolled in CO.26 [ NCT02870920 ] – a phase II clinical trial that assessed durvalumab + tremelimumab in patients with heavily pretreated mCRC – using whole exome sequencing (WES) of archival primary tumor tissue and circulating tumor DNA (ctDNA) sequencing of serial plasma samples that were taken at baseline, week 8 and on progression. Results: Six out of 95 (6.3%) patients diagnosed with KRAS/ NRAS-mutated mCRC showed ‘neo- RAS-wildtype’ reversions at the time of baseline or week-8 ctDNA collection for the CO.26 trial. The majority (4/6) had falling tumor mutation burden (TMB) but stable or rising maximum mutation allele frequency (MAF) when reversions occurred. These were unlikely false negatives from non-secreting cancers as there were continued strong presence of other somatic clonal mutations (e.g., TP53, ATM). The majority (4/6) of reversions were transient, with mutations reappearing with progressive disease. ‘Neo- RAS-wildtype’ revertors had numerically longer median overall survival (OS) from date of cancer diagnosis to death compared those with persistent RAS mutations (7.7 vs. 4.2 yrs, HR = 0.65, 95% CI 0.31 to 1.36, log-rank P= 0.26). However, ‘neo- RAS-wildtype’ revertors were earlier-stage at diagnosis compared to those with persistent RAS mutations (33% vs. 63% had synchronous metastases, χ2 P= 0.15), and had lower disease burden upon enrollment (50% vs. 68.5% had liver metastases, P= 0.17; 33% vs. 75% had > 4 lesions, P= 0.03*). Survival from stage IV diagnosis to death did not differ between those with reverted vs. persistent RAS mutations (median 3.8 vs. 3.2 yrs, HR = 0.77, 95% CI 0.35 to 1.72, P= 0.52). ‘Neo- RAS-wildtype’ reversions were not associated with side of primary tumors ( P= 0.41), archival BRAF/MEK/ERK-mutant status ( P= 0.16, 1.00, 0.09), baseline HER2 amplifications ( P= 1.00), or baseline TMB ( P= 0.21). Conclusions: We identified a 6.3% prevalence of ‘neo- RAS-wildtype’ reversions in the CO.26 trial, however only 2.1% of patients had persistent loss when serial time points were considered. Further research is needed to understand if ‘neo- RAS-wildtype’ revertors may benefit from anti-EGFR therapy. Clinical trial information: NCT02870920 .

Trop-2 mRNA expression and association with clinical outcomes with sacituzumab govitecan (SG) in patients with HR+/HER2– metastatic breast cancer (mBC): Biomarker results from the phase 3 TROPiCS-02 study.

1082 Background: SG is a Trop-2–directed antibody-drug conjugate approved in multiple countries for patients with metastatic triple-negative breast cancer who received at least 1 prior systemic therapy and in the US for patients with pretreated HR+/HER2– mBC. In the TROPiCS-02 study, SG significantly improved progression-free survival (PFS; median, 5.5 vs 4.0 mo; HR, 0.66 [95% CI, 0.53-0.83]; P=0.0003) and overall survival (OS; median, 14.4 vs 11.2 mo; HR, 0.79 [95% CI, 0.53-0.83]; P=0.020) over treatment of physician’s choice (TPC) in patients with pretreated, endocrine-resistant HR+/HER2– mBC. In TROPiCS-02 post hoc analyses, SG improved OS regardless of Trop-2 expression by immunohistochemistry (IHC; Rugo HS, et al. SABCS 2022), but association using more sensitive assays are lacking. Here, we examine efficacy outcomes for SG versus TPC by Trop-2 gene ( TACSTD2) mRNA expression and the correlation of TACSTD2 expression with other genes. Methods: Patients with HR+/HER2– mBC who received ≥1 prior taxane, endocrine therapy and a CDK4/6 inhibitor, and 2-4 prior chemotherapy regimens for mBC were randomized 1:1 to SG or TPC. The primary endpoint was PFS by central review per RECIST v1.1. RNA was isolated from archival tumor tissue samples using AllPrep DNA/RNA kits and libraries prepared with TruSeq RNA Exome Prep Kit. Sequencing was via NovaSeq (2x150bp). Gene expression quantitation was performed using Salmon. TACSTD2 expression was defined as high or low via median cut. Results: In the mRNA analytical cohort (N=197), 49% had TACSTD2 high expression (SG, n=51; TPC, n=46), and 51% had TACSTD2 low expression (SG, n=47; TPC, n=53). Baseline characteristics were generally consistent between TACSTD2 expression subsets and the intention-to-treat population. A positive concordance between TACSTD2expression and Trop-2 IHC (H-score) was observed (categorical concordance 71%; Cohen’s kappa = 0.41). TACSTD2 expression was similar across HER2 IHC0 and HER2-Low subgroups (log2 transcripts per million [TPM] of 3.36 [IQR, 2.76-4.22] and log2TPM of 3.44 [IQR, 2.59-4.22], respectively). SG showed a numerically higher median PFS ( TACSTD2 high, 7.3 vs 5.6 mo; TACSTD2 low, 5.6 vs 2.8 mo) versus TPC regardless of TACSTD2 expression. Similarly, for OS, outcomes favored SG over TPC regardless of TACSTD2 expression. Conclusions: This mRNA-based biomarker analysis demonstrated that SG improves PFS and OS outcomes in patients with pretreated, endocrine-resistant HR+/HER2– mBC regardless of Trop-2 mRNA expression. There was no correlation between Trop-2 mRNA expression and HER2 status. Trop-2 mRNA expression was not predictive of benefit with SG. Additional studies are needed to determine whether Trop-2 mRNA expression has a prognostic role in mBC. Clinical trial information: NCT03901339 .

Alliance A022104/NRG-GI010: A randomized phase II trial testing the efficacy of triplet versus doublet chemotherapy to achieve clinical complete response in patients with locally advanced rectal cancer—The Janus Rectal Cancer trial.

TPS3640 Background: Recent data have demonstrated that in locally advanced rectal cancer (LARC), a total neoadjuvant therapy (TNT) approach improves compliance with chemotherapy and increases rates of tumor response compared to neoadjuvant chemoradiation (CRT) alone. They further indicate that the optimal sequencing of TNT involves consolidation (rather than induction) chemotherapy to optimize complete response rates. Data, largely from retrospective studies, have also shown that patients (pts) with clinical complete response (cCR) after neoadjuvant therapy may be managed safely with the watch and wait approach (WW) instead of preemptive total mesorectal resection (TME). However, the optimal consolidation chemotherapy regimen to achieve cCR has not been established, and a randomized clinical trial has not robustly evaluated it as a primary endpoint. Collaborating with a multidisciplinary oncology team and pt groups, we designed this NCI-sponsored study of chemotherapy intensification to address these issues and to drive up cCR rates, to provide opportunity for organ preservation and improve quality of life for pts. Methods: In this Alliance for Clinical Trials in Oncology randomized phase II trial (1:1), up to 312 pts with microsatellite stable LARC, clinical stage T4N0, any T, N+ or T3N0 requiring abdominoperineal resection or coloanal anastomosis and distal margin within 12 cm of anal verge will be enrolled. Stratification factors include tumor stage (T4 vs T1-3), nodal stage (N+ vs N0) and distance from anal verge (0-4; 4-8; 8-12 cm). Pts will be randomized to receive neoadjuvant long course CRT (LCRT) followed by consolidation doublet (mFOLFOX6 or CAPOX) or triplet chemotherapy (mFOLFIRINOX) for 4 months. LCRT in both arms involves 4500 cGy in 25 fractions over 5 weeks (w) + 900 cGy boost in 5 fractions with a fluoropyrimidine (capecitabine preferred). Pts will undergo assessment 8-12 w post-TNT completion for the primary endpoint of cCR per previously validated criteria and recommended WW and surveillance if cCR is achieved or TME if an incomplete response is noted. Secondary objectives include time-to event outcomes (disease-free and overall survival, organ preservation time and time to distant metastasis) and adverse effects. Statistical power, based on cCR, incorporates a one-sided alpha = 0.048 and power = 90% yielding 312 patients (156 per arm). Biospecimens including archival tumor tissue, matched / normal blood samples and serial rectal MRI will be collected for exploratory correlative research. This study, activated in late 2022, is open across the NCTN and is actively recruiting. Support: U10CA180821, U10CA180882, U24 CA196171; https://acknowledgments.alliancefound.org . U10CA180868 (NRG); U10CA180888 (SWOG); Clinicaltrials.gov ID: NCT05610163 Clinical trial information: NCT05610163 .

Evaluating the use of circulating tumor DNA (ctDNA) in patients with urothelial cancer in the context of FGFR-targeted therapy.

4577 Background: Fibroblast growth factor receptor (FGFR) inhibitors (e.g., erdafitinib) are increasingly important in the management of FGFR-mutated urothelial carcinoma. FDA-approved archival tissue testing for specific FGFR alterations was implemented as a companion diagnostic for erdafitinib. However, longitudinal sequencing studies indicate variable tumor FGFR status over time, and erdafitinib resistance mechanisms in metastatic urothelial carcinoma (mUC) are underreported. This ongoing study aims to evaluate the accuracy of cell-free DNA (cfDNA) compared to archival tissue testing in mUC for FGFR alterations detection, and to evaluate genomic mechanisms of erdafitinib resistance in cfDNA at progression. Methods: Patients with progressing mUC who were undergoing archival tissue testing for FGFR1-3 mutations and/or fusions and who had blood samples drawn during the management of their metastatic disease were eligible. Plasma cfDNA and matched leukocyte DNA were subjected to deep targeted sequencing with a custom panel including UC-specific gene loci and all clinically approved hotspots in FGFR1+2 and all exons and introns of FGFR3. Results: As of January 2023, 109 patients from 6 sites were enrolled. Median age at diagnosis was 71, 33% had upper urinary tract primaries, and 76% were male. Tissue and cfDNA results for comparison were available for 69 patients to date. Actionable somatic FGFR alterations were found in the tissue of 15 patients (31%); the most common alteration was the FGFR3 p.S249C mutation (67%). 50 of the analyzed cfDNA samples had detectable somatic circulating tumor DNA (ctDNA) variant allele fraction of 0.5% (72%). Of those, 49 had an evaluable tissue test result. Analysis of this subset revealed high concordance (92%) between the two test methods. With the assumption that archival tissue testing is considered the ‘gold standard’, sensitivity is 93% and specificity is 91%. The four discordant results comprised one cfDNA test with undetectable FGFR3-TACC3 fusion, which was detected in tissue and three positive ctDNA test results in patients with FGFR wild-type tissue tests. In one case at erdafitinib progression, ctDNA revealed multiple subclonal populations with distinct FGFR3 gatekeeper mutations suggesting polyclonal resistance. Conclusions: This ongoing study suggests cfDNA is a valuable minimally invasive adjunct to tissue-based assays for the detection of FGFR alterations to identify patients for FGFR inhibitor therapy and to monitor for mechanisms of resistance.

MAIN-CAV: Phase III randomized trial of maintenance cabozantinib and avelumab versus avelumab after first-line platinum-based chemotherapy in patients (pts) with metastatic urothelial cancer (mUC; Alliance A032001).

TPS4609 Background: First-line platinum-based chemotherapy followed by maintenance avelumab (Av) is the current preferred standard of care in patients (pts) with mUC who do not progress after platinum-based chemotherapy. There is an unmet need to further improve outcomes by combining Av with an effective, non-cross resistant therapy with non-overlapping toxicity. CABO is an oral inhibitor of MET, VEGFR and TAM family receptors involved in tumor growth, angiogenesis and immune cell regulation and has shown efficacy in UC in combination with PD-1/PD-1L1 inhibitors. We hypothesize that CABO-Av combination will be synergistic in pts with mUC with an acceptable safety profile and will improve upon the benefit seen with Av maintenance in mUC. Methods: MAIN-CAV is a phase III randomized, multicenter, international trial for locally advanced/mUC pts (including N3 only disease) who do not progress after 4-6 cycles of any platinum-based chemotherapy (gem-cis, gem-carbo, MVAC or ddMVAC). 654 adult pts will be randomized 1:1 within 3-10 weeks (wk) after last dose of chemotherapy to receive Av 800 mg IV every 2 wk or combination of Av and CABO 40 mg orally daily for up to 2 yrs. Key eligibility criteria include ECOG PS 0-1, no prior use of immunotherapy (exception of BCG), no central nervous system metastases, no major surgery within 4 wk, no uncontrolled hypertension or cardiovascular disorders. Pts will be stratified based on 1) best response to 1L therapy: complete response vs partial response vs stable disease and 2) presence or absence of visceral metastases. The primary endpoint is overall survival (OS) with assumptions of one-sided alpha of 0.025, power of 80%, median OS of 21 months (mo) on Av arm and hazard ratio (HR) of 0.75, thus hypothesizing a median OS of 28 mo on CABO-Av combination arm. Key secondary endpoints include progression-free survival, safety, tolerability, and activity of CABO-Av compared to Av alone based on RECIST 1.1 and iRECIST criteria and PD-L1 status of pts’ tumors. Quality of life (QOL) will be assessed using EQ-5D-5L, PROMIS-Fatigue 4a, EORTC QLQ-C30, EORTC QLQ-BLM30 between pts on CABO-avelumab vs avelumab alone. Biomarkers of response and resistance to Av will be assessed using baseline archival tissues, baseline and serial blood, ctDNA, stool and urine. Imaging studies will test correlation of established and new radiomic signatures with OS, adverse events and QOL and incorporate both radiologic and biologic features to predict outcomes. This trial would be the first to systematically address whether adding a multitargeted TKI, CABO to Av leads to improved clinical outcomes compared to Av alone. Clinical trial information: NCT05092958 .