Citations

4017 Background: Combined MEK inhibition (MEKi) and PD-L1 blockade significantly improved progression-free survival (PFS) versus PD-L1 monotherapy in patients with advanced biliary tract cancer (BTC) following first-line chemotherapy (NCT03201458). Further study has shown MEKi enhances tumor immunogenicity but impairs host T cell activation/priming. The addition of immune agonists, e.g. a CD27 agonist, can rescue T cell function in the setting of systemic MEKi in vivo and may be an effective strategy to optimize MEKi’s immunomodulatory potential when used in combination with checkpoint blockade. Methods: We conducted a randomized ph 2 trial (NCT04941287) evaluating Atezolizumab in combination with the CD27 immune agonist (CDX-1127 [Varlilumab]) with or without the addition of a MEKi (Cobimetinib) in patients with unresectable, previously treated, BTC. Adults with pathologically-confirmed BTC, s/p at least 1 prior line (no more than 2) of systemic therapy, measurable disease, and ECOG PS ≤1 were enrolled. Patients who had received previous PD-[L]1 were eligible. The study was planned for 64 evaluable subjects randomized in a 1:1 ratio, stratified by BTC site, to either AV (Atezolizumab [840mg IV days 1,15])+ Varlilumab [3mg/kg IV days 1, 15]) or CAV (Cobimetinib [60mg oral daily days 1-21, off 22-28] + Atezolizumab + Varlilumab). Overall response rate (ORR) and PFS were co-primary endpoints. The primary correlative outcome was treatment-related changes in CD8+ infiltrating T cells. Results: A preplanned interim analysis based on objective response rates did not meet the threshold for continuance in either treatment arm, so the trial was closed early for futility. In total, 57 patients were enrolled (n = 29 [CAV], n = 28 [AV], 67% had intrahepatic cholangiocarcinoma, and 33% had received previous PD-[L]1. Both CAV and AV regimens were well-tolerated without new safety signals. Adding CDX-1127 did not appear to meaningful increase immunotoxicity beyond established PD-L1 toxicity profiles. ORR was 0% (CAV) and 4% (AV). With a median follow up time of 6.2 months, median PFS was 2.2 (CAV) and 1.8 (AV) months (HR 0.71 [0.40,1.25]). In PD[L]1-experienced patients, median PFS was 3.6 (CAV) and 1.7 (AV) months (HR 0.44 [0.14,1.33]). Median OS was 10.2 (CAV) and 6.1 (AV) months (HR 0.76 [0.37,1.55]). In PD[L]1-experienced patients, median OS was 6.4 (CAV) and 4.4 (AV) months for CAV and AV (HR 0.68 [0.19,2.42]). Primary correlative endpoint and updated survival will be reported at time of meeting. Conclusions: The combination of Atezolizumab and Varlilumab with or without Cobimetinib was safe but did not improve clinical outcomes in advanced stage BTC patients treated in later lines. Though not statistically significant, treatment with CAV demonstrated numerically favorable PFS/OS compared AV among immunotherapy-experienced patients. Clinical trial information: NCT03201458 .

3078 Background: Q901 is a potent, covalently binding CDK7 inhibitor with excellent specificity for CDK7 against other protein kinases. Transcriptional regulation by CDK7 inhibition in cancer cells leads to DNA damage repair response inhibition and increased genomic instability. Q901 also regulates cell cycle checkpoints by inhibiting T-loop phosphorylation and transcriptionally downregulating CDK1, 2 and 4. In preclinical in vivo models, intravenous (iv) administration of Q901 once a week and once every three-week dosing regimen was well tolerated and showed significant antitumor activity. The safety profile, pharmacokinetics (PK), pharmacodynamics (PD) and efficacy data for 18, 36 and 60 mg/m2 are presented. Methods: QRNT-009 (NCT05394103) is an ongoing Phase 1/2 multicenter, open-label, dose escalation and expansion study. Q901 is administered iv once weekly for four weeks, then once every two weeks thereafter in patients with advanced or metastatic ovarian cancer, castration-resistant prostate cancer (CRPC), breast cancer, endometrial cancer, colorectal cancer, small cell lung cancer (SCLC), or pancreatic cancers. Results: As of data cutoff (12Jan2024), 17 patients received Q901 across 3 dose levels: 5 patients at 18 mg/m2, 4 patients at 36 mg/m2, and 8 patients at 60 mg/m2. The median prior lines of systemic therapy were 4 (range 2 - 17). Of 17 patients who received Q901 across all doses, there were no treatment related SAEs, treatment discontinuations, or dose reductions. Most common TRAEs ≥ 15% were nausea (29.4%), anemia (23.6%) and fatigue (23.5%). As of data cutoff, no DLTs were observed. All plasma PK analyses across dose levels showed dose dependent increase of AUC0-last and Cmax. No major metabolite was observed. POLR2A, which is a CDK7 target engagement marker showed biologically effective change starting from 18 mg/m2. 1 patient with pancreatic cancer who received 18 mg/m2 had a partial response with CA19-9 reduction from 4,632 to 219. 2 patients at 18 mg/m2 and 2 patients at 36 mg/m2 had stable disease. Additional safety and efficacy data will be presented. Conclusions: Preliminary data from QRNT-009 study showed that selective CDK7 inhibitor Q901 is well tolerated. Preliminary antitumor activity and pharmacodynamic observations are encouraging. Dose escalation is ongoing to identify MTD or recommended dose for further studies. Clinical trial information: NCT05394103 .

Background Improper sizing of the humeral head component in anatomic total shoulder arthroplasty (ATSA) can overstuff the joint, potentially compromising outcomes. The purpose of this study was to validate a novel method of evaluating glenohumeral joint overstuffing in which superoinferior and mediolateral overstuffing can be evaluated independently relative to the native humeral anatomy. Methods We identified 25 patients who underwent ATSA and the best Grashey radiograph taken within 1 year of follow-up was assessed using our proposed technique. First, a circle overlaying the implanted humeral head was made. Then, Iannotti's Perfect Circle (IPC) was drawn as originally described. Measurements of superior and medial overstuffing were made using our proposed axes. Inter-rater reliability was assessed by computing interclass correlation coefficients (ICC) using a one-way model. Measurements were summarized as the mean and range, with positive values denoting overstuffing. Results The inter-rater reliability for all measurements was excellent (ICC > 0.9). Compared to our method, the IPC method would have missed 77% of overstuffed cases. Conclusion We present a reproducible method to assess glenohumeral joint overstuffing in ATSA. This technique addresses limitations of other methods that underestimate overstuffing. Further study is needed to establish a clinically significant value of overstuffing based on the proposed method.

TPS5125 Background: B7-H3 is a member of the B7 superfamily, which includes PD-L1 (B7-H1) and PD-L2 (B7-DC). Enoblituzumab is a humanized Fc-optimized B7-H3–targeting antibody that induces antibody-dependent cellular cytotoxicity (ADCC). A recent investigator-initiated trial demonstrated that enoblituzumab therapy, used in the neoadjuvant prostate cancer setting, is feasible, safe, may enhance short-term clinical outcomes, and appears to stimulate intratumoral immune activation including CD8+ T cell infiltration and peripheral expansion of tumor-infiltrating T-cell clones that correlated with undetectable PSA at 1-year post-prostatectomy. To assess the impact of enoblituzumab on recurrence-free survival following prostatectomy, a phase 2, randomized, neoadjuvant clinical trial in high-risk localized prostate cancer patients has been started. We hypothesize that targeting B7-H3 with enoblituzumab will delay or prevent recurrence following prostatectomy compared to standard of care (SOC) . Methods: The HEAT trial is an investigator-initiated, multi-center, randomized, phase 2 study that is presently enrolling (NCT06014255). Eligible patients will undergo a pre-treatment prostate biopsy and conventional imaging (CT and bone scan) as well as PSMA-PET. Patients who have clinical stage cT1c-T3b, cN0 cM0 disease by conventional imaging (N1 by PSMA allowed with up to 3 LNs each ≤1 cm) will be eligible as long as concurrent hormonal or radiation therapy is not given. Prostate biopsy, within 3 months of enrollment, needs to show at least 3 positive cores containing at least 1 core with at least 50% disease involvement with Gleason ≥4+3=7 disease (with at least 1 additional high-risk feature such as PSA>20 ng/ml or cT3) or a Gleason sum ≥8. Patients will receive enoblituzumab at a dose of 15mg/kg IV biweekly for 6 doses (12 weeks) on the treatment arm, followed by prostatectomy, or will be scheduled for prostatectomy directly within 4-8 weeks on the SOC arm. 219 patients will be randomized (2:1) to treatment versus SOC. Pre-treatment, on-treatment, and post-treatment biomarkers of response and resistance will be collected. Patients will be followed according to standard institutional practices, but will require PSA evaluations every 3 (±1) months during year 1 and every 6 (±2) months during years 2-5. In both arms, salvage or adjuvant therapy will occur after biochemical or radiographic progression. The primary endpoint is recurrence-free survival (RFS) defined as any metastasis events, local pelvic visceral or lymph node recurrence, detectable prostate-specific antigen (PSA), or start of subsequent local or systemic therapy (including salvage or adjuvant therapy), or death for any cause, whichever occurs first. Secondary endpoints include additional clinical and immunologic correlates. Clinical trial information: NCT06014255 .

e15543 Background: In the last two decades, colorectal cancer (CRC) mortality has been decreasing in the United States (US). However, the mortality trends for the different subtypes of CRC, including different sides of colon, rectosigmoid, and rectal cancer remain unclear. Methods: We analyzed death certificate data from CDC WONDER from 1999 to 2020. We calculated age-adjusted mortality rates (AAMR) per 100,000 individuals of CRC and its different subtypes and examined the trends over time by estimating the average annual percent change (AAPC) using the Joinpoint Regression Program. Results: From 1999 to 2020, 1,166,099 deaths were attributed to CRC, of which 957,182 deaths (82.08%) were due to colon cancer, 148,862 deaths (12.77%) from rectal cancer, and 60,055 deaths (5.15%) from rectosigmoid cancer. The overall CRC rates decreased significantly from 26.42 (95% CI, 26.20-26.64) to 15.98 (95% CI, 15.84-16.12) per 100,000 individuals, with AAPC of -2.41 (95% CI, -2.55, -2.27). However, the AAMR of rectosigmoid cancer increased significantly from 0.82 (95% CI, 0.78 -0.86) to 1.08 (95% CI, 1.04-1.11) per 100,000 individuals and the AAMR of right-sided colon cancer increased from 0.57 (95% CI, 0.54-0.60) to 0.70 (95% CI, 0.67-0.73) per 100,000 individuals, with AAPC of +1.10 (95%, 0.21-2.00) and +2.06 (95% CI, 0.85 - 3.27) respectively. Men had higher AAMR of CRC than women (23.90 [95% CI, 23.84-23.96] vs. 17.03 [95% CI, 16.99-17.08] per 100,000 individuals). African Americans had the highest AAMR of CRC (26.93 [95% CI, 26.79-27.07]), followed by Whites (19.60 [95%, 19.56-19.64] per 100,000 individuals), American Indians (14.53 [95%, 14.15-14.92] per 100,000 individuals), and Asians (13.04 [95%, 12.89-13.19] per 100,000 individuals). The overall AAMR of CRC decreased for those aged ≥ 50 years but increased significantly from 1.02 to 1.58 per 100,000 individuals for those aged 15-49 years, with an AAPC of +0.75. The AAMR from CRC was the highest in the Midwest (21.04 [95% CI, 20.96-21.12] per 100,000 individuals), followed by the South (20.51 [95% CI, 20.44-20.57]), the Northeast (20.30 [95% CI, 20.22-20.38] per 100,000 individuals), and the West (18.03 [95% CI, 17.95-18.10] per 100,000 individuals). Rural populations had higher AAMR than urban populations (22.40 [95% CI, 22.30-22.49] vs. 19.60 [95%, 19.56-19.64] per 100,000 individuals). Conclusions: Although overall CRC mortality declined, there were rising trends in young-onset CRC, rectosigmoid cancer, and right-sided colon cancer. Disparities persist in terms of sex, race, geographic region, and urbanization level, emphasizing the need for targeted public health measures.

3519 Background: KRAS G12D commonly occurs in pancreatic (PDAC) and colorectal (CRC) cancers. Though developing KRAS G12D inhibitors is pertinent, it is expected that primary and acquired resistance will limit efficacy, similar to those seen with KRAS G12C inhibitors. Here, we assessed the prevalence and outcomes of candidate mutations co-occurring with KRAS G12D in PDAC and CRC using liquid biopsy data. Methods: Patients with advanced CRC and PDAC tested with Guardant360 genomic profiling from 2020 to 2023 (~2500 & 3500 samples) were included. Candidate resistance mutations were determined based on mutations reported following KRAS G12C inhibition. Patients with advanced CRC and PDAC tested with Guardant360 at Mayo Clinic (2016-2023) (1158 & 904 samples) were assessed for overall survival (OS). Patients were divided into three groups: KRAS G12D alone, KRAS G12D with candidate resistance alterations, and KRAS G12D not detected (ND). OS was estimated using Kaplan-Meier method. Cox regression was used for multivariable survival analyses. Results: The Guardant360 database reported KRAS G12D in 16.5% of CRC and 40.2% of PDAC samples. The Table below summarizes the most frequent candidate resistance alterations co-occurring with KRAS G12Dincluding point mutations of KRASand PIK3CAand amplifications of EGFR, KRAS, BRAFand MYC. In the Mayo cohort, 8.9% of CRC and 23.5% of PDAC patients had KRAS G12D. In CRC, those with KRAS G12Dand ≥1 candidate resistance alteration had a significantly lower OS (mOS 18.7m) than KRAS G12D alone (30.9m), and ND (37.3m) ( p=0.004). The presence of concurrent candidate resistance alterations with KRAS G12D remained a poor prognostic factor with HR 2.1 (95% CI: 1.3 – 3.2, p=0.001) after adjusting for age and other patient characteristics. Similarly, in PDAC, those with KRAS G12D and ≥1 resistance mutation had significantly lower OS (mOS 8.1m) than KRAS G12D alone (10.5m) and ND (16.1m) (p<0.0001). In multivariable analyses, both KRAS G12D with candidate resistance alterations (HR 2.1, 95% CI: 1.4-3.3, p<0.001) and G12Dalone (HR 1.6; 1.3–2.0, p<0.001) were poor prognostic factors. Among patients with serial Guardant360, treatment response trended with KRAS G12D variant allele frequency. Conclusions: Circulating tumor DNA testing is a useful tool to reveal candidate molecular alterations linked to potential resistance to KRAS G12D targeting in patients with KRAS G12D gastrointestinal cancers. KRAS G12D with these concurrent molecular alterations is a poor prognostic factor in both PDAC and CRC. [Table: see text]

The development and performance of two mass spectrometry (MS) workflows for the intraoperative diagnosis of isocitrate dehydrogenase (IDH) mutations in glioma is implemented by independent teams at Mayo Clinic, Jacksonville, and Huashan Hospital, Shanghai. The infiltrative nature of gliomas makes rapid diagnosis necessary to guide the extent of surgical resection of central nervous system (CNS) tumors. The combination of tissue biopsy and MS analysis used here satisfies this requirement. The key feature of both described methods is the use of tandem MS to measure the oncometabolite 2-hydroxyglutarate (2HG) relative to endogenous glutamate (Glu) to characterize the presence of mutant tumor. The experiments i) provide IDH mutation status for individual patients and ii) demonstrate a strong correlation of 2HG signals with tumor infiltration. The measured ratio of 2HG to Glu correlates with IDH-mutant (IDH-mut) glioma ( P < 0.0001) in the tumor core data of both teams. Despite using different ionization methods and different mass spectrometers, comparable performance in determining IDH mutations from core tumor biopsies was achieved with sensitivities, specificities, and accuracies all at 100%. None of the 31 patients at Mayo Clinic or the 74 patients at Huashan Hospital were misclassified when analyzing tumor core biopsies. Robustness of the methodology was evaluated by postoperative re-examination of samples. Both teams noted the presence of high concentrations of 2HG at surgical margins, supporting future use of intraoperative MS to monitor for clean surgical margins. The power of MS diagnostics is shown in resolving contradictory clinical features, e.g., in distinguishing gliosis from IDH-mut glioma.