Abstract CT514: A phase I, open-label, dose-escalation study investigating a low-density lipoprotein receptor-related protein (LRP) 5/6 inhibitor, BI 905677, in patients with advanced solid tumors

Background: Ligand-dependent Wnt signaling, mediated by LRP5/6, is highly activated in a subset of solid tumors. Activation leads to accumulation of intracellular β-catenin and expression of β-catenin-dependent genes that promote cancer cell proliferation and treatment resistance. BI 905677 is a bi-paratopic antibody that binds LRP5/6 and blocks binding of Wnt ligands. This study (NCT03604445) aimed to identify the maximum tolerated dose (MTD) and determine the recommended dose for BI 905677 in patients with advanced solid tumors. Pharmacokinetics and efficacy will also be evaluated.

Methods: This is a Phase I, open-label, non-randomized study of BI 905677, administered intravenously, in patients with advanced, unresectable and/or metastatic solid tumors. Patients were refractory to or not eligible for standard therapy. Patients were treated at increasing intravenous doses of BI 905677 (0.05, 0.1, 0.2, 0.4, 0.8, 1.6, 2.4, 2.8 and 3.6 mg/kg every 3 weeks [q3w]) until progression. Subsequent patients within a cohort were treated ≥ 72 hours apart to allow adequate monitoring for cytokine release syndrome and implementation of preventive measures if required.

Results: As of November 23, 2021, 37 patients have received BI 905677. The median age was 56 years (range 32-77) and most were male (65%) and had ECOG PS 1 (51%). At 3.6 mg/kg, 3/3 patients experienced dose-limiting toxicities (DLTs) and dose was reduced to 2.8 mg/kg, which was determined as the MTD. Patients received a median of 2.0 cycles (range 1-6). Across all dose levels, 19 patients (51%) experienced Grade ≥ 3 adverse events (AEs). The most common Grade ≥ 3 AEs were vomiting (11%), hyponatremia (8%), anemia (5%), diarrhea (5%), abdominal pain (5%), nausea (5%), hypokalemia (5%), pain (5%) and increased alkaline phosphatase (5%). No related Grade ≥ 3 AEs were reported for doses ≤ 1.6 mg/kg, and BI 905677 was considered well tolerated ≤ 2.8 mg/kg. There were two Grade 5 events not related to study drug (tumor lysis syndrome and disease progression). DLTs observed at 3.6 mg/kg were hyponatremia, increased β-CTX expression (> 2-fold versus baseline), diarrhea, hyperbilirubinemia and vomiting. Exposure to BI 905677 increased in an approximately dose-proportional manner over the complete dose groups tested. No drug accumulation between Cycle 1 and Cycle 2 was observed for any cohort. Only six patients presented with anti-drug antibodies (ADAs), including one with pre-existing ADAs. Axin2 expression by reverse transcription PCR was reduced in paired skin biopsies but no dose dependency was observed. Across all doses, the best response was stable disease (n = 13; 35%).

Conclusions: BI 905677 was well tolerated, with the MTD established as 2.8 mg/kg q3w. An expansion cohort to evaluate the activity of BI 905677 in a molecularly selected population for Wnt ligand dependence is planned.

Citation Format: Elena Élez, Heinz-Josef Lenz, Maja de Jonge, Rona Yaeger, Toshihiko Doi, Linda Pronk, Michael Teufel, Kristell Marzin, Josep Tabernero. A phase I, open-label, dose-escalation study investigating a low-density lipoprotein receptor-related protein (LRP) 5/6 inhibitor, BI 905677, in patients with advanced solid tumors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr CT514.

Abstract 3634: Integrative analysis of the contribution of genomic and clinical factors to worse clinical outcomes in non-Hispanic Black patients with colorectal cancer

Non-Hispanic Black (NHB) patients have higher incidence and higher mortality from colorectal cancer (CRC) than non-Hispanic white (NHW) patients. The extent to which this aggressive behavior in NHB patients is driven by differences in cancer genomics is presently unknown.

We analyzed clinical and genomic data from 3,963 CRC patients treated at Memorial Sloan Kettering, including 336 (8%) NHB and 3,627 (92%) NHW patients. Tumors were sequenced using the clinical MSK-IMPACT test, a targeted next-generation DNA sequencing assay that identifies mutations, copy number changes and structural rearrangements in 341-505 genes using solid tissue and matched blood.

No significant differences by race were observed for stage at diagnosis or sex. While the difference in median age at diagnosis was small (53.4 for NHB vs. 55 years for NHW patients, p=0.012), significantly fewer NHB patients were diagnosed after 65 years of age (17% vs. 27%, p=0.001). Right-sided colon tumors were more common among NHB patients (37% vs. 25%, p=0.02); the proportion of rectal tumors was similar in both racial groups (31% in NHB vs. 34% in NHW patients, n.s.). Hypermutated tumors, including tumors with microsatellite instability (MSI) and POLE hypermutants, were more frequent among NHW patients (12% vs. 8%, p=0.02). Right-sided tumors were more frequently MSI/hypermutated in the NHW patients (27% vs. 13%, p=0.008), whereas no differences by race were observed for left-sided colon (5% vs. 1%, n.s.) or rectal primaries (4% vs. 5%, n.s.).

Genomic analysis of the non-hypermutated tumors revealed no significant differences in tumor mutational burden or fraction of genome altered between racial groups. Tumors in NHB patients were enriched in KRAS mutations (60% vs. 45%, p<0.001), but G12C mutations accounted only for 3% of all driver KRAS mutations in NHB patients vs. 8% of all driver mutations in NHW patients (p=0.01). BRAF mutations were more frequent in non-hypermutated NHW patients (7% vs. 3%, p=0.006), but the overall frequency of RTK/RAS pathway alterations was higher in the NHB group (74% vs. 66%, p=0.004).

Even though all patients were treated at the same single institution during the study, NHB patients had shorter overall survival (OS) from the time of sequencing (median 28 months [95% CI 25-38] vs. 50 months [95% CI 47-53], p<0.001). NHB patients also had worse OS [HR 1.64, CI 1.3 - 2.1, p<0.001] in a multivariate analysis using Cox Proportional-Hazards and accounting for age at diagnosis, stage at diagnosis, body mass index, primary tumor location, MSI status and oncogenic alterations in APC, TP53, KRAS, SMAD4, and BRAF.

Our data confirms that NHB patients with CRC have worse clinical outcomes than NHW patients. Clinically relevant differences in the frequency of alterations in cancer driver genes are observed based on racial origin, but they do not fully explain the difference in survival.

Citation Format: Henry Walch, Anisha Luthra, Walid K. Chatila, Fan Wu, Debyani Chakravarty, Chin-Tung Chen, Rupa Sood, Dana M. Omer, Jesse J. Smith, Nikolaus Schultz, Karuna Ganesh, Julio Garcia-Aguilar, Rona Yaeger, Francisco Sanchez-Vega. Integrative analysis of the contribution of genomic and clinical factors to worse clinical outcomes in non-Hispanic Black patients with colorectal cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 3634.

Single agent PD-1 blockade as curative-intent treatment in mismatch repair deficient locally advanced rectal cancer

LBA5

Background: Neoadjuvant chemotherapy and radiation followed by surgical resection of the rectum is a standard treatment for locally advanced rectal cancer. A subset of rectal cancer is mismatch repair deficient. Since mismatch repair deficient colorectal cancer is responsive to PD-1 blockade in the metastatic setting, we hypothesized that locally advanced mismatch repair deficient rectal cancer is sensitive to checkpoint blockade and may alter the requirements for chemoradiotherapy and surgery. Methods: We conducted a prospective phase II study in which single agent dostarlimab, an anti PD-1 monoclonal antibody, was administered every 3 weeks for 6 months in patients with mismatch repair deficient stage II and III rectal adenocarcinoma, to be followed by standard chemoradiation and surgery. Patients who achieved a clinical complete response were eligible for omission of chemoradiation and surgery. Results: Twelve patients initiated treatment and have at least 6 months of follow up. All 12 (100%, 95% CI:74%-100%) achieved a clinical complete response with no evidence of tumor on MRI, FDG-PET, endoscopic visualization, digital rectal exam, or biopsy, which satisfied the study’s co-primary endpoint. To date, no patients have required chemoradiation or surgery, and no cases of progression or recurrence have been noted during follow up (range 6-25 months). No serious adverse events > grade 3 were observed. Conclusions: Mismatch repair deficient locally advanced rectal cancer is exceptionally sensitive to single agent PD-1 blockade. Longer follow up is needed to assess response duration. Clinical trial information: NCT04165772.

Functional impact of somatic mutations in early-onset (EO) versus average onset (AO) microsatellite stable (MSS) stage III colorectal cancer (CRC)

3613

Background: Analysis of the IDEA database demonstrates significantly worse disease-free survival in high-risk stage III EO CRC vs AO CRC, regardless of adjuvant therapy intensity or duration. Critically this analysis omits somatic mutational data and germline status. Enrichment of TP53 in EO metastatic CRC (mCRC) is well described and functionality of individual TP53 mutations has been proposed as a potential mechanism of chemotherapy resistance. The prognostic and functional impact of somatic mutations merits analysis in the EO high-risk Stage III cohort. Methods: The Memorial Sloan Kettering MSKCC IMPACT database was queried for MSS Stage III AO CRC (≥50 yrs) and EO CRC ( < 50 yrs) patients(pts); clinico-pathological characteristics, systemic therapies received, and survival outcomes were reviewed. MSI, POLE mutated or hereditary syndrome associated tumors were excluded. We further classified TP53 mutations as GOF (gain of function) versus non GOF/ LOF (loss of function) (Pan M, JCO. 2022, Muller PA, Cancer cell. 2014). Results: 272 pts were included in the analysis (EO = 184, AO = 88). 50% of the EO and 62.5 % of the AO cohorts were male. Tumors were predominantly adenocarcinoma (EO 89% vs AO 91%), moderately differentiated (EO 78% vs AO 74%) and left sided (EO 77% vs AO 48.8%). 87% of the EO and 63.6 % of the AO cohort were TP53mut (p value 0.0003); TP53mut was enriched in the EO cohort regardless of sidedness but there was no significant difference in TP53 mutations between EO high vs low risk. Classifying by 7 putative GOF mutations (R175H, R248Q/W, R249S, R273H/L and R282W) 28.7% of the EO cohort harbored a GOF mutation vs 19.6% of the AO cohort. There was no statistically significant survival difference between pts with TP53mut tumors vs TP53 wild type (TP53wt) in the entire cohort (AO+EO) (p 0.041) or EO or AO cohorts (p 0.049). There was no significant difference in survival outcomes across all cohorts of TP53mut groups, both high and low risk, both GOF and non GOF, treated with 3 vs 6 months of chemotherapy (p 0.67). The EO TP53wt group was enriched relative to the EO TP53mut group for KRAS (60% vs 32%), BRAF (11% vs 4%), and PI3K driver alterations (PIK3CA, 20% vs 13%) and PTEN: (8% vs 3%) In the multivariate survival analysis of EO Stage III CRC BRAFmut status is highly statistically significant (p < 0.001). Conclusions: EO Stage III CRC is enriched for TP53 mutations regardless of sidedness and GOF mutations are identified in a higher proportion of EO CRC than AO CRC. We found no statistically significant difference in survival by TP53mut status across the entire MSS Stage III CRC cohort. There was no interaction between TP53mut status, duration of chemotherapy and overall survival. The functional impact of additional molecular features is being explored and the novel prognostic significance of BRAF demonstrated in this EO Stage III cohort requires further validation.

Clinicopathologic characterization of ERK2 E322K mutation in solid tumors: Implications for treatment and drug development

3135

Background: MAPK1 encodes ERK2, a kinase component of the mitogen activated signaling (MAPK) pathway. ERK2 E322K is a known activating mutation that leads to increased phosphorylation and ERK signaling. In vitro studies found this mutation to be associated with resistance to dabrafenib, trametinib, but potential sensitivity to ERK inhibitors. Despite its potential as a drug target, little is known about the clinicopathologic characteristics of this hotspot mutation across solid tumors. Methods: Patients with solid tumors underwent tumor next-generation sequencing at Memorial Sloan Kettering Cancer Center between Jan 2015 and Sep 2020 using the MSK-IMPACT assay. Using the cBioPortal database and clinical charts, we analyzed tumors harboring MAPK1/ERK2 E322K mutations, assessed their clinicopathologic characteristics, co-mutational status and overall survival (OS). OS was measured from time of tumor sequencing to date of death or last follow-up. Results: A total of 37 tumor samples from 35 patients were identified in 59,822 tumors sequenced (0.06%) to harbor an ERK2 E322K mutation. The distribution across tumor types was as follows: head and neck squamous cell carcinoma (29%), bladder cancer (20%), lymphomas (9%), colorectal cancers (9%), gastric cancers (9%), cholangiocarcinoma (6%), cervical cancers (6%), lung cancers (6%), germ cell tumor (3%), Merkel cell carcinoma (3%), and breast cancers (3%). The OS in patients with metastatic disease and ERK2 E322K was 22.29 months (95%CI: 7.56-NA) months. Other mutations in RAS pathway frequently co-occurred with ERK2 E322K mutation (17/37, 46%). Concurrent mutations are also involved in pathways of cell cycle (71%), PI3K (71%), TP53 (66%), NOTCH (57%), RTK (51%), HIPPO (29%), TGF-beta (29%), WNT (26%), NRF2 (20%), MYC (14%). The median TMB score of samples from solid malignancies was 12.3 (range:0-101, quartiles: 6.9-33.0) mutation/Mb. Two patients (2/35, 6%) had microsatellite-instability high (MSI-H) tumors. The most frequent concurrent activating mutations include ARID1A (29%), FBXW7 (26%), PI3KCA (22%), PI3KR1/2/3 (20%), CDKN2A (11%), PTEN (8%), BRCA1/2(8%), FGFR3 (8%), BRAF (6%), Only one of these 35 patients received treatment targeting BRAF/MEK/ERK pathway and achieved partial response. One patient with NSCLC harboring a concurrent EGFR L858R mutation did not respond to erlotinib. One patient with PI3KCA mutated head and neck cancer did not respond to PI3K inhibitor. Two patients had TMB score of 100.9 and 12.9 mutation/Mb had partial response to pembrolizumab. Conclusions: ERK2 E322K mutation is a rare oncogenic mutation across diverse solid tumor types, associated with a high co-occurrence of other activating mutations and a high TMB. The lack of response to other targeted therapies suggests ERK2 E322K is a potential driver mutation. These findings may inform treatment and further development of ERK inhibitors.

The frequency of second primary malignancies and colonic polyps in Lynch syndrome with MSI tumors following immune checkpoint blockade

10505

Background: Lynch syndrome (LS) is caused by germline mutations in DNA mismatch repair genes and is characterized by microsatellite instability (MSI) status of associated tumors. MSI sensitizes tumors to immune checkpoint inhibition (ICI). The incidence of second primary malignancies and colonic polyps in LS patients with MSI tumors following ICI has not been evaluated. Methods: The Memorial Sloan Kettering LS database was queried for all patients with cancer who received ≥1 cycle of ICI using an IRB approved protocol. LS was confirmed by presence of a germline pathogenic/likely pathogenic alteration in a DNA mismatch repair gene ( MLH1, MSH2, MSH6, PMS2, EPCAM). Tumor and matched normal DNA sequencing was performed via MSK-IMPACT, an IRB approved protocol (NCT01775072). MSI status was assessed using MSIsensor. Results: At our center, 131 patients with LS received ICI mostly (73.3%) in the context of metastatic cancer. While 108 patients received ICI for an MSI tumor, 23 LS patients received ICI for a MSS (Microsatellite Stable) tumor (4 hepatobiliary, 3 colorectal, 3 CNS, 2 endometrial, 2 gastroesophageal, 2 renal, 2 sarcoma, 5 other). Five patients (3.8%) developed ≥1 second primary malignancy while on or following ICI comprised of an MSI small bowel adenocarcinoma, MSI upper tract urothelial cancer, 2 MSS prostate cancers, MSS HCC and MSI sebaceous neoplasm; 1 patient developed both MSS prostate cancer and MSI urothelial cancer on ICI. All five patients’ primary malignancy was MSI. Only a minority of patients underwent surveillance colonoscopies post completion of ICI (31.3%, (41/131)). Of these 41, nine (22%, (9/41)) were identified to have polyps including 8 tubular adenomas and 1 tubulo-villous adenoma. Median time to development of a polyp was 22 months (95% CI 16.82-27.18) from last colonoscopy and 13 months (95% CI 4-25 months) from last ICI. Notably amongst the 23 LS patients whose tumors were MSS, 14 had progression on ICI. Conclusions: Herein, we demonstrate that in LS-patients in receipt of ICI for cancer treatment, the risk of a second primary cancer and polyps remain high following treatment with ICI. Biological mechanisms underlying immune escape warrant further investigation. Surveillance strategies should be continued for LS patients post ICI.

Quality of life with encorafenib plus cetuximab with or without binimetinib treatment in patients with BRAF V600E-mutant metastatic colorectal cancer: patient-reported outcomes from BEACON CRC

Background

In the BEACON CRC study (NCT02928224), encorafenib plus cetuximab with binimetinib {9.3 versus 5.9 months; hazard ratio (HR) [95% confidence interval (CI)]: 0.60 [0.47-0.75]} or without binimetinib [9.3 versus 5.9 months; HR (95% CI): 0.61 (0.48-0.77)] significantly improved overall survival (OS) compared with the previous standard of care (control) in patients with BRAF V600E metastatic colorectal cancer (mCRC). Quality of life (QoL) was a secondary endpoint, assessed using validated instruments.

Patients and methods

BEACON CRC was a randomized, open-label, phase III study comparing encorafenib plus cetuximab with or without binimetinib and the investigator’s choice of irinotecan plus cetuximab or FOLFIRI plus cetuximab (chemotherapy control) in patients with previously treated BRAF V600E mCRC. Patient-reported QoL assessments included the European Organization for Research and Treatment of Cancer Quality of Life Questionnaire Core 30 (EORTC) and Functional Assessment of Cancer Therapy—Colorectal (FACT-C). The primary outcome for these tools was time to definitive 10% deterioration.

Results

Encorafenib plus cetuximab, both with and without binimetinib, was associated with longer median times to definitive 10% deterioration versus the control group in the EORTC Global Health Status scale [HR (95% CI): 0.65 (0.52-0.80) versus 0.61 (0.49-0.75), respectively] and the FACT-C functional well-being subscale [HR (95% CI): 0.62 (0.50-0.76) versus 0.58 (0.47-0.72), respectively]. Consistent results were observed across all subscales of the EORTC and FACT-C instruments. QoL was generally maintained during treatment for the global EORTC and FACT-C scales.

Conclusions

In addition to improving OS, encorafenib plus cetuximab with or without binimetinib delays QoL decline in previously treated patients with BRAF V600E-mutant mCRC.

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BEACON CRC compares encorafenib + cetuximab ± binimetinib to chemotherapy in previously treated BRAF V600E mCRC.

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Encorafenib + cetuximab had longer time to 10% deterioration versus control in QoL and functional well-being scales.

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Encorafenib + cetuximab ± binimetinib delays QoL decline in previously treated patients with BRAF V600E mCRC.

Different hotspot p53 mutants exert distinct phenotypes and predict outcome of colorectal cancer patients

The TP53 gene is mutated in approximately 60% of all colorectal cancer (CRC) cases. Over 20% of all TP53-mutated CRC tumors carry missense mutations at position R175 or R273. Here we report that CRC tumors harboring R273 mutations are more prone to progress to metastatic disease, with decreased survival, than those with R175 mutations. We identify a distinct transcriptional signature orchestrated by p53R273H, implicating activation of oncogenic signaling pathways and predicting worse outcome. These features are shared also with the hotspot mutants p53R248Q and p53R248W. p53R273H selectively promotes rapid CRC cell spreading, migration, invasion and metastasis. The transcriptional output of p53R273H is associated with preferential binding to regulatory elements of R273 signature genes. Thus, different TP53 missense mutations contribute differently to cancer progression. Elucidation of the differential impact of distinct TP53 mutations on disease features may make TP53 mutational information more actionable, holding potential for better precision-based medicine.

Survival After Induction Chemotherapy and Chemoradiation Versus Chemoradiation and Adjuvant Chemotherapy for Locally Advanced Rectal Cancer

BACKGROUND

Total neoadjuvant therapy (TNT) improves tumor response in locally advanced rectal cancer (LARC) patients compared to neoadjuvant chemoradiotherapy alone. The effect of TNT on patient survival has not been fully investigated.

MATERIALS AND METHODS

This was a retrospective case series of patients with LARC at a comprehensive cancer center. Three hundred and eleven patients received chemoradiotherapy (chemoRT) as the sole neoadjuvant treatment and planned adjuvant chemotherapy, and 313 received TNT (induction fluorouracil and oxaliplatin-based chemotherapy followed by chemoradiotherapy in the neoadjuvant setting). These patients then underwent total mesorectal excision or were entered in a watch-and-wait protocol. The proportion of patients with complete response (CR) after neoadjuvant therapy (defined as pathological CR or clinical CR sustained for 2 years) was compared by the χ2 test. Disease-free survival (DFS), local recurrence-free survival, distant metastasis-free survival, and overall survival were assessed by Kaplan-Meier analysis and log-rank test. Cox regression models were used to further evaluate DFS.

RESULTS

The rate of CR was 20% for chemoRT and 27% for TNT (P=.05). DFS, local recurrence-free survival, metastasis-free survival, and overall survival were no different. Disease-free survival was not associated with the type of neoadjuvant treatment (hazard ratio [HR] 1.3; 95% confidence interval [CI] 0.93-1.80; P = .12).

CONCLUSIONS

Although TNT does not prolong survival than neoadjuvant chemoradiotherapy plus intended postoperative chemotherapy, the higher response rate associated with TNT may create opportunities to preserve the rectum in more patients with LARC.

Immune biomarkers and response to checkpoint inhibition of BRAFV600 and BRAF non-V600 altered lung cancers

BACKGROUND

While 2-4% of lung cancers possess alterations in BRAF, little is known about the immune responsiveness of these tumours.

METHODS

Clinical and genomic data were collected from 5945 patients with lung cancers whose tumours underwent next-generation sequencing between 2015 and 2018. Patients were followed through 2020.

RESULTS

In total, 127 patients with metastatic BRAF-altered lung cancers were identified: 29 tumours had Class I mutations, 59 had Class II/III alterations, and 39 had variants of unknown significance (VUS). Tumour mutation burden was higher in Class II/III than Class I-altered tumours (8.8 mutations/Mb versus 4.9, P < 0.001), but this difference was diminished when stratified by smoking status. The overall response rate to immune checkpoint inhibitors (ICI) was 9% in Class I-altered tumours and 26% in Class II/III (P = 0.25), with median time on treatment of 1.9 months in both groups. Among patients with Class I-III-altered tumours, 36-month HR for death in those who ever versus never received ICI was 1.82 (1.17-6.11). Nine patients were on ICI for >2 years (two with Class I mutations, two with Class II/III alterations, and five with VUS).

CONCLUSIONS

A subset of patients with BRAF-altered lung cancers achieved durable disease control on ICI. However, collectively no significant clinical benefit was seen.

Same-Cell Co-Occurrence of RAS Hotspot and BRAF V600E Mutations in Treatment-Naive Colorectal Cancer

PURPOSE

Mitogen-activated protein kinase pathway-activating mutations occur in the majority of colorectal cancer (CRC) cases and show mutual exclusivity. We identified 47 epidermal growth factor receptor/BRAF inhibitor-naive CRC patients with dual RAS hotspot/BRAF V600E mutations (CRC-DD) from a cohort of 4,561 CRC patients with clinical next-generation sequencing results. We aimed to define the molecular phenotypes of the CRC-DD and to test if the dual RAS hotspot/BRAF V600E mutations coexist within the same cell.

MATERIALS AND METHODS

We developed a single-cell genotyping method with a mutation detection rate of 96.3% and a genotype prediction accuracy of 92.1%. Mutations in the CRC-DD cohort were analyzed for clonality, allelic imbalance, copy number, and overall survival.

RESULTS

Application of single-cell genotyping to four CRC-DD revealed the co-occurrence of both mutations in the following percentages of cells per case: NRAS G13D/KRAS G12C, 95%; KRAS G12D/NRAS G12V, 48%; BRAF V600E/KRAS G12D, 44%; and KRAS G12D/NRAS G13V, 14%, respectively. Allelic imbalance favoring the oncogenic allele was less frequent in CRC-DD (24 of 76, 31.5%, somatic mutations) compared with a curated cohort of CRC with a single-driver mutation (CRC-SD; 119 of 232 mutations, 51.3%; P = .013). Microsatellite instability-high status was enriched in CRC-DD compared with CRC-SD (23% v 11.4%, P = .028). Of the seven CRC-DD cases with multiregional sequencing, five retained both driver mutations throughout all sequenced tumor sites. Both CRC-DD cases with discordant multiregional sequencing were microsatellite instability-high.

CONCLUSION

Our findings indicate that dual-driver mutations occur in a rare subset of CRC, often within the same tumor cells and across multiple tumor sites. Their presence and a lower rate of allelic imbalance may be related to dose-dependent signaling within the mitogen-activated protein kinase pathway.

First data for sotorasib in patients with pancreatic cancer with KRAS p.G12C mutation: A phase I/II study evaluating efficacy and safety

360490

Background: KRAS mutation is present in 90% of pancreatic ductal adenocarcinomas with p.G12C accounting for 1% to 2% of these mutations. Sotorasib, a small molecule that specifically and irreversibly inhibits KRASG12C, has been investigated in the CodeBreaK100 trial in patients with KRASG12C-mutated advanced solid tumors. Herein, we report on the largest dataset evaluating efficacy and safety of a KRASG12C inhibitor in patients with pretreated KRASG12C-mutated pancreatic cancer. Methods: CodeBreaK100 (NCT03600883) is an international, single arm, phase I/II study evaluating the efficacy and safety of sotorasib in patients with KRASG12C-mutated advanced solid tumors with ≥ 1 prior systemic therapy unless intolerant or ineligible for available therapies. The primary efficacy endpoint is confirmed objective response rate (ORR), assessed by blinded independent central review (BICR) per RECIST 1.1. Secondary endpoints include duration of response (DoR), disease control rate (DCR), progression-free survival (PFS), and overall survival (OS). Results: As of November 1, 2021, 38 patients with pancreatic cancer (mean age: 65 years, 76.3% male) from the combined phase I/II study received sotorasib 960 mg once daily. Stage IV disease was present in 55.3% of patients at diagnosis, and in all patients at enrollment. Baseline ECOG scores were 0, 1, or 2 in 31.6%, 57.9%, and 10.5% of patients, respectively. Most patients (79%) had ≥ 2 prior lines of therapy (median: 2 [range: 1-8]). Median treatment duration was 4.1 months with a median follow-up of 16.8 months. Eight patients had confirmed partial response by BICR with a resulting ORR of 21.1% (95% CI: 9.55%-37.32%). DCR was 84.2% (Table 1). Treatment-related adverse events (TRAEs) of any grade occurred in 16 (42.1%) patients. Grade ≥ 3 TRAEs occurred in 6 patients: diarrhea (2); fatigue (2); abdominal pain, ALT increase, AST increase, pleural effusion, and pulmonary embolism (1 each). No TRAEs were fatal or resulted in sotorasib discontinuation. Conclusions: Sotorasib demonstrated clinically meaningful anticancer activity and tolerability in patients with heavily pretreated KRASG12C-mutated advanced pancreatic cancer, who have limited treatment options and poor prognosis. Clinical trial information: NCT03600883. [Table: see text]

Genomic characterization of metastatic patterns from prospective clinical sequencing of 25,000 patients

Metastatic progression is the main cause of death in cancer patients, whereas the underlying genomic mechanisms driving metastasis remain largely unknown. Here, we assembled MSK-MET, a pan-cancer cohort of over 25,000 patients with metastatic diseases. By analyzing genomic and clinical data from this cohort, we identified associations between genomic alterations and patterns of metastatic dissemination across 50 tumor types. We found that chromosomal instability is strongly correlated with metastatic burden in some tumor types, including prostate adenocarcinoma, lung adenocarcinoma, and HR+/HER2+ breast ductal carcinoma, but not in others, including colorectal cancer and high-grade serous ovarian cancer, where copy-number alteration patterns may be established early in tumor development. We also identified somatic alterations associated with metastatic burden and specific target organs. Our data offer a valuable resource for the investigation of the biological basis for metastatic spread and highlight the complex role of chromosomal instability in cancer progression.

Evaluation of baseline BRAF V600E mutation in circulating tumor DNA and efficacy response from the BEACON study

162

Background: In the randomized phase 3 BEACON study, encorafenib + binimetinib + cetuximab (triplet) and encorafenib + cetuximab (doublet) regimens improved overall survival (OS) and objective response rate (ORR) versus standard of care (control) in patients (pts) with previously treated BRAF V600E-mutant metastatic colorectal cancer. To identify whether detection of a BRAF V600E mutation in baseline circulating tumor DNA (ctDNA) correlated with response, we evaluated the status and allele frequency of BRAF V600E compared with clinical outcomes. Methods: Plasma samples were collected at Cycle 1 Day 1 and end of treatment for ctDNA analysis and analyzed using GuardantOMNI. Variant allele frequency (VAF) of BRAF V600E was grouped into high (> median) and low (≤median) categories. Low VAF samples included those where BRAF V600E mutation was not detected or no ctDNA was detected. ORR, based on blinded independent central review, and OS were compared between treatment arms according to VAF levels. ORR comparisons used Chi-square test and logistic regression. OS was summarized using the Kaplan-Meier method. HRs and 95% CIs were estimated using a Cox model. Additional correlation analyses between BRAF V600E status in baseline tumor tissue, as well as clonality, will be presented. Results: Baseline plasma samples were analyzed from 544 of 631 pts in the ctDNA analysis: 88.3% (196/222) in the triplet arm, 86.6% (187/216) in the doublet arm, and 83.4% (161/193) in the control arm. BRAF V600E mutations were detected in 90.4% (492/544) of pts (90.3% [177/196] triplet, 90.4% [169/187] doublet, and 90.7% [146/161] control). Pts with BRAF V600E mutations with high VAF had significantly ( P≤0.0001) increased ORR (95% CI) in the triplet and doublet arms (27.3% [19.5–36.8] and 15.9% [9.7–25.0], respectively) compared with control (0% [0.0–4.3]). Similar response trends were observed in pts with BRAF V600E mutations with low VAF (triplet: 28.9% [20.8–38.9]; doublet: 25.3% [17.7–34.6]; control: 5.3% [2.1–12.8]). OS decreased in BRAF V600E pts with high VAF (median OS [95% CI]: triplet 7.2 [6.0–8.0] months, n = 99; doublet 5.4 [4.4–6.1] months, n = 88; control 4.2 [3.4–4.8] months, n = 85) compared with pts with low VAF (triplet 14.8 [10.2–19.8] months, n = 97; doublet 14.8 [11.7–23.0] months, n = 99; control 9.3 [7.5–11.3] months, n = 76). Conclusions: ctDNA analyses showed the majority of pts in BEACON analyzed at baseline had a detectable BRAF V600E mutation. Increased response rates were observed in pts treated with triplet or doublet therapy compared with control, independent of VAF. Pts with a higher VAF for BRAF V600E may have a worse prognosis. Clinical trial information: NCT04607421.

KRYSTAL-1: Updated activity and safety of adagrasib (MRTX849) in patients (Pts) with unresectable or metastatic pancreatic cancer (PDAC) and other gastrointestinal (GI) tumors harboring a KRASG12C mutation

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Background: KRAS, the most frequently mutated oncogene in cancer, is a key mediator of the RAS/MAPK signaling cascade that promotes cellular growth and proliferation. KRAS mutations occur in approximately 90% of pancreatic cancer, and approximately 2% of these are KRASG12C mutations. Adagrasib, an investigational agent, is a KRASG12C inhibitor that irreversibly and selectively binds KRASG12C, locking it in its inactive state; adagrasib has been optimized for favorable pharmacokinetic (PK) properties, including long half-life (̃24 h), extensive tissue distribution, dose-dependent PK, as well as CNS penetration. Methods: KRYSTAL-1 (NCT03785249) is a multicohort Phase 1/2 study evaluating adagrasib as monotherapy or in combinations in pts with advanced solid tumors harboring a KRASG12C mutation. Here we report preliminary data from pts enrolled in a Phase 2 cohort evaluating single-agent adagrasib administered orally at 600 mg BID in previously treated pts with unresectable or metastatic solid tumors (excluding NSCLC and CRC), including pancreatic and other GI cancers. Study endpoints include clinical activity, safety, and PK. Results: The data cutoff was 10 September 2021. A total of 42 pts were enrolled in this cohort (median age 63.5 years, range 21–89; 52% female; 71% white; 29%/71% ECOG PS 0/1; median 2 prior lines of therapy, range 1–7; median follow-up 6.3 months), of whom 30 pts had KRASG12C-mutant GI tumors (12 PDAC, 8 biliary tract, 5 appendiceal, 2 gastro-esophageal junction, 2 small bowel, and 1 esophageal). In a preliminary analysis, 27 pts with GI tumors were evaluable for clinical activity; partial responses (PRs) were seen in 41% (11/27, including 3 unconfirmed PRs); the disease control rate (DCR) was 100% (27/27). Of the 12 pts with PDAC (median 3 prior lines of therapy; median follow-up 8.1 months), 10 were evaluable for clinical activity; PRs were seen in 50% (5/10, including 1 unconfirmed PR); the DCR was 100% (10/10). Median progression-free survival (PFS) was 6.6 months (95% CI 1.0–9.7), and treatment was ongoing in 50% of pts with PDAC. Among the 17 evaluable pts with other GI tumors, 6 achieved PR (35%; 2 unconfirmed) with a DCR of 100% (17/17); 11 pts were still receiving treatment. In the overall cohort, treatment-related adverse events of any grade occurred in 91% (38/42), the most frequent being nausea (48%), diarrhea (43%), vomiting (43%), and fatigue (29%); grade 3/4 events occurred in 21% of pts, with no grade 5 events. Conclusions: Adagrasib monotherapy is well tolerated and demonstrates encouraging clinical activity in pretreated pts with PDAC and other GI tumors harboring a KRASG12C mutation. Further exploration of adagrasib is ongoing in this pt population (NCT03785249). Clinical trial information: NCT03785249.

A phase 1b study of sotorasib, a specific and irreversible KRASG12C inhibitor, in combination with other anticancer therapies in advanced colorectal cancer (CRC) and other solid tumors (CodeBreaK 101)

TPS214

Background: Approximately 3% of patients (pts) with CRC have the oncogenic Kirsten rat sarcoma viral oncogene homolog (KRAS) p.G12C mutation. Sotorasib, a small molecule that specifically and irreversibly inhibits the KRAS G12C mutant protein, has demonstrated modest clinical activity and no dose-limiting toxicities as a single agent in heavily pretreated pts with KRAS p.G12C-mutated CRC. The combination of sotorasib with other anticancer therapies, such as EGFR or MEK inhibitors, may enhance antitumor efficacy and counteract potential escape mechanisms. Other attractive partners for sotorasib in CRC include biologics and chemotherapy combinations. The CodeBreaK 101 master protocol is designed to evaluate safety, tolerability, pharmacokinetics (PK), and efficacy of multiple sotorasib-based combinations in pts with KRAS p.G12C mutated solid tumors. Key subprotocols with CRC combination treatment arms are highlighted here. Methods: This is a phase 1b, open-label study evaluating sotorasib alone and in combination regimens in pts with advanced KRAS p.G12C mutated CRC, NSCLC, and other solid tumors. Key regimens being explored in CRC include (1) Subprotocol A: Sotorasib + trametinib (MEK inhibitor) +/- panitumumab (EGFR inhibitor), (2) Subprotocol H: Sotorasib + panitumumab and sotorasib + panitumumab + FOLFIRI, and (3) Subprotocol M: Sotorasib + bevacizumab-awwb + FOLFIRI or FOLFOX. Key eligibility criteria include advanced or metastatic solid tumor with KRAS p.G12C mutation identified through molecular testing in treatment-naïve and pretreated patients depending on cohort. Primary endpoints include dose-limiting toxicities and treatment-emergent or treatment-related adverse events. Secondary endpoints include PK profile of combination regimens and efficacy (objective response, disease control, duration of response, time to response, and progression-free survival assessed per RECIST 1.1, and overall survival). Enrollment is ongoing. Contact Amgen Medical Information for more information: medinfo@amgen.com (NCT04185883). Abbreviations: EGFR = epidermal growth factor receptor; FOLFIRI = 5-fluorouracil + leucovorin + irinotecan; FOLFOX = 5-fluorouracil + leucovorin + oxaliplatin; MEK = mitogen-activated protein kinase. Clinical trial information: NCT04185883.

PD-1 blockade alone for mismatch repair deficient (dMMR) locally advanced rectal cancer

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Background: Total neoadjuvant therapy with induction chemotherapy and chemoradiation (chemoRT) is the standard treatment for locally advanced rectal adenocarcinomas. Mismatch repair deficient (dMMR) rectal tumors respond poorly to neoadjuvant chemotherapy. PD-1 blockade is effective in patients with metastatic dMMR colorectal cancers, but its efficacy has not been established in the neoadjuvant setting. The purpose of this study is to evaluate the clinical benefit of neoadjuvant PD-1 blockade in dMMR locally advanced rectal cancer. Methods: We designed a prospective, single-arm, phase II study in which patients with stage II and III dMMR rectal cancer receive neoadjuvant dostarlimab (anti-PD-1) for a total of 6 months. The co-primary objectives are to determine the overall response rate (ORR) and pathologic complete response (pCR) or clinical complete response rate (cCR) with or without chemoRT. Tumor assessment with endoscopic evaluation is performed at baseline, 6 weeks, 3 months and 6 months; imaging is performed at pretreatment baseline, 3 months and 6 months. Patients with cCR by previously established criteria are eligible for non-operative management without chemoRT. Those with residual disease after neoadjuvant dostarlimab receive standard chemoRT. Following chemoRT, any patient failing to achieve a cCR is then managed surgically. Results: A total of 13 patients have been enrolled, with median age 52 years (range 26-78), 77% female, and 92% with node-positive disease by rectal MRI. The ORR is 100% in the 12 patients who have undergone at least a 3-month evaluation. Seven patients have completed induction therapy and all 7 (100%) have achieved a cCR and are undergoing observation without chemoRT or surgery. The rate of progressive disease thus far is 0%. No patients have required chemoRT or surgery. There have been no serious adverse events. Conclusions: Single agent neoadjuvant PD-1 blockade with dostarlimab is effective and well-tolerated in locally advanced dMMR rectal adenocarcinoma and allows patients to avoid chemoradiation and surgery. This suggests a potential new paradigm for treatment of dMMR locally advanced rectal cancer. Follow up and further patient accrual is ongoing. Clinical trial information: NCT04165772.

BREAKWATER safety lead-in (SLI): Encorafenib + cetuximab (EC) ± chemotherapy for first-line (1L) treatment (tx) of BRAF V600E-mutant (BRAFV600E) metastatic colorectal cancer (mCRC)

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Background: Currently, there are no 1L tx options indicated specifically for patients (pts) with BRAFV600E mCRC. Based on results of BEACON CRC (NCT02928224), BRAF inhibitor encorafenib + EGFR inhibitor cetuximab was approved for tx of previously treated pts with BRAFV600E mCRC. BREAKWATER (NCT04607421), an ongoing, open-label, global, multicenter, randomized phase 3 study, evaluates 1L EC ± chemotherapy for tx of pts with BRAFV600E mCRC. Here we present preliminary data on safety and pharmacokinetics (PK) from the BREAKWATER SLI, which aimed to identify the chemotherapy backbone for EC for the phase 3 portion of BREAKWATER. Methods: SLI inclusion criteria were BRAFV600E mCRC (determined using tumor tissue or blood); evaluable disease (RECIST v1.1); ≤1 prior systemic tx for mCRC; European Cooperative Oncology Group performance status (ECOG PS) 0/1; and adequate bone marrow, hepatic, and renal function. Pts previously treated with BRAF/EGFR inhibitors or both oxaliplatin and irinotecan were excluded. Pts received encorafenib 300 mg daily + cetuximab 500 mg/m2 every 2 weeks (Q2W) + either FOLFIRI Q2W or mFOLFOX6 Q2W in 28-day cycles. The primary endpoint was frequency of dose-limiting toxicities (DLTs). PK were a secondary endpoint. Data cutoff date: Sep 13, 2021. Results: 57 pts were enrolled (EC + FOLFIRI, n = 30; EC + mFOLFOX6, n = 27). Median (range) age was 57 (28–78) years; 25% were Asian; 65% had ECOG PS 0; 37% had ≥3 organs involved; 58% were treatment naive. At cutoff date, tx was ongoing in 45 (79%) pts. Median (range) duration of tx for encorafenib in EC + FOLFIRI and EC + mFOLFOX6 was 15 (0–31) and 14 (0–27) weeks, respectively. One DLT was observed: grade 4 neutropenia in 1 pt in EC + FOLFIRI. Tx-emergent all-cause serious adverse events (AEs) occurred in 20% and 19% and grade ≥3 AEs in 33% and 56% of pts in EC + FOLFIRI and EC + mFOLFOX6, respectively. The table shows frequent (all grade in ≥30% pts or grade ≥3 in ≥10% with either tx) tx-emergent all-cause AEs. One pt died due to disease progression. In EC + FOLFIRI, in the presence of steady-state encorafenib, AUCinf of irinotecan and its active metabolite, SN-38, significantly decreased ̃25% and ̃40%, respectively, compared with values in the absence of encorafenib. In EC + mFOLFOX6, oxaliplatin PK was not significantly altered by steady-state encorafenib. Conclusions: Based on these data, BREAKWATER phase 3 will compare EC ± mFOLFOX6 with mFOLFOX6/FOLFOXIRI/CAPOX ± bevacizumab. Clinical trial information: NCT04607421. [Table: see text]

Transcriptomic profiling to identify subsets of immune hot locally advanced rectal adenocarcinomas with favorable outcomes after neoadjuvant treatment

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Background: Understanding the role of the tumor microenvironment in the response to chemotherapy and radiation in patients with locally advanced rectal cancer (LARC, stage II-III) can lead to the identification of novel immunologic biomarkers to preselect patients who can avoid surgery and benefit from watch-and-wait strategies. Methods: We performed DNA and RNA sequencing of pre-treatment biopsies from 89 LARC patients who received neoadjuvant therapy, including 5 microsatellite unstable (MSI) and 84 microsatellite stable (MSS) patients. We computed single-sample gene set enrichment analysis (ssGSEA) scores for immune infiltrates and signaling pathways implicated in tumor progression. Immunofluorescence and hematoxylin-eosin staining of tumor slides was performed to confirm significant correlations with RNA-Seq estimates of immune markers. Other genomic variables were also included in the analysis, such as tumor mutational burden (TMB), fraction of genome altered by copy number changes, whole genome duplication events and somatic mutations in rectal cancer driver genes and pathways. Results were largely replicated using an independent cohort of 42 LARC samples with publicly available data from The Cancer Genome Atlas (TCGA). Results: Since MSI tumors are known to have a distinct immunologic profile, we separated them into their own group and performed unsupervised hierarchical clustering on the MSS tumors. We identified a set of immune hot MSS tumors (n = 7) with extensive immune infiltration. These tumors had low TMB and were predominantly classified as CMS4 (5/7). None of the 12 patients in the combined MSI and immune hot MSS groups recurred during the length of our study and they had response rates > 50% (vs. < 25% in the rest of MSS patients). MSI and immune hot MSS tumors had lower frequency of TP53 and APC mutations, and they exhibited increased levels of T cell infiltration. In particular, we observed overexpression of markers for Th1 cells, which produce inflammatory cytokines (e.g., IFN-gamma) and are associated with antitumor immunity. Genes encoding protein targets of immune checkpoint blockade, such as PDCD1 (PD-1), CD274 (PD-L1), CTLA4, HAVCR2 (TIM3) and LAG3, were also overexpressed in the immune hot MSS and - to a lesser extent – the MSI tumors, suggesting that these patients might benefit from the use of immune checkpoint inhibitors. Conclusions: Our results uncover a unique LARC tumor immune profile evident in the pre-treatment setting that could be used to better prognosticate rectal cancer patients and develop novel therapeutic strategies.

BREAKWATER: Randomized phase 3 study of encorafenib (enco) + cetuximab (cet) ± chemotherapy for first-line treatment (tx) of BRAF V600E-mutant (BRAFV600) metastatic colorectal cancer (mCRC)

TPS211

Background: Approximately 10% of patients (pts) with mCRC have BRAF mutations (mostly V600E). First-line tx options for BRAFV600E mCRC are limited to cytotoxic chemotherapy ± anti-VEGF or anti-EGFR; or immune checkpoint inhibitors in pts with MSI-H tumors. In Europe, Japan, and USA, the combination of BRAF inhibitor enco + EGFR inhibitor cet is approved for tx of BRAFV600E mCRC after prior therapy. In BEACON CRC, enco + cet resulted in a median overall survival (OS) of 9.3 months (95% confidence interval [CI]: 8.0–11.3) and an objective response rate (ORR) of 19.5% (95% CI: 14.5%–25.4%) in previously treated pts with BRAFV600E mCRC (median follow-up: 12.8 months); 57.4% of pts had grade 3/4 adverse events (AEs), and 9% discontinued due to AEs. Given the poor prognosis of pts with BRAFV600E mCRC and based on the efficacy and tolerability of enco + cet from BEACON CRC, the BREAKWATER study will evaluate the efficacy and safety of enco + cet ± chemotherapy in tx-naive pts with BRAFV600E mCRC. Methods: BREAKWATER is an open-label, global, multicenter, randomized, phase 3 study with a safety lead-in (SLI). Approximately 60 and 870 pts will be enrolled in the SLI and phase 3 parts of the study, respectively. Pts must have mCRC with BRAF V600E-mutation (determined using tumor tissue or blood); ECOG performance status 0/1; and adequate bone marrow, hepatic, and renal function. Pts in the SLI must have evaluable disease (RECIST v1.1) and have received ≤ 1 prior tx regimen; those previously treated with a BRAF or EGFR inhibitor, or both oxaliplatin and irinotecan, will be excluded. Pts in the phase 3 study must have measurable disease and be tx naive for metastatic disease. Study tx and endpoints are shown in the table. Enrollment began on 06-Jan-2021. Clinical trial information: NCT04607421. [Table: see text]

Management of adverse events from the treatment of encorafenib plus cetuximab for patients with BRAF V600E-mutant metastatic colorectal cancer: insights from the BEACON CRC study

Colorectal cancer is the second leading cause of cancer deaths worldwide, with a 5-year relative survival of 14% in patients with metastatic colorectal cancer (mCRC). Patients with BRAF V600E mutations, which occur in ∼10%-15% of patients with mCRC, have a poorer prognosis compared with those with wild-type BRAF tumours. The combination of the BRAF inhibitor encorafenib with the epidermal growth factor receptor inhibitor cetuximab currently represents the only chemotherapy-free targeted therapy approved in the USA and Europe for previously treated patients with BRAF V600E-mutated mCRC. As a class, BRAF inhibitors are associated with dermatologic, gastrointestinal, and renal events, as well as pyrexia and secondary skin malignancies. Adverse event (AE) profiles of specific BRAF inhibitors vary, however, and are affected by the specific agents given in combination. In patients with mCRC, commonly reported AEs of cetuximab monotherapy include infusion reactions and dermatologic toxicities. Data from the phase III BEACON CRC study indicate that the combination of encorafenib with cetuximab has a distinct safety profile. Here we review the most frequently reported AEs that occurred with this combination in BEACON CRC and best practices for managing and mitigating AEs that require more than standard supportive care.

A Comprehensive Comparison of Early-Onset and Average-Onset Colorectal Cancers

BACKGROUND

The causative factors for the recent increase in early-onset colorectal cancer (EO-CRC) incidence are unknown. We sought to determine if early-onset disease is clinically or genomically distinct from average-onset colorectal cancer (AO-CRC).

METHODS

Clinical, histopathologic, and genomic characteristics of EO-CRC patients (2014-2019), divided into age 35 years and younger and 36-49 years at diagnosis, were compared with AO-CRC (50 years and older). Patients with mismatch repair deficient tumors, CRC-related hereditary syndromes, and inflammatory bowel disease were excluded from all but the germline analysis. All statistical tests were 2-sided.

RESULTS

In total, 759 patients with EO-CRC (35 years, n = 151; 36-49 years, n = 608) and AO-CRC (n = 687) were included. Left-sided tumors (35 years and younger = 80.8%; 36-49 years = 83.7%; AO = 63.9%; P < .001 for both comparisons), rectal bleeding (35 years and younger = 41.1%; 36-49 years = 41.0%; AO = 25.9%; P = .001 and P < .001, respectively), and abdominal pain (35 years and younger = 37.1%; 36-49 years = 34.0%; AO = 26.8%; P = .01 and P = .005, respectively) were more common in EO-CRC. Among microsatellite stable tumors, we found no differences in histopathologic tumor characteristics. Initially, differences in TP53 and Receptor Tyrosine Kinase signaling pathway (RTK-RAS)alterations were noted by age. However, on multivariate analysis including somatic gene analysis and tumor sidedness, no statistically significant differences at the gene or pathway level were demonstrated. Among advanced microsatellite stable CRCs, chemotherapy response and survival were equivalent by age cohorts. Pathogenic germline variants were identified in 23.3% of patients 35 years and younger vs 14.1% of AO-CRC (P = .01).

CONCLUSIONS

EO-CRCs are more commonly left-sided and present with rectal bleeding and abdominal pain but are otherwise clinically and genomically indistinguishable from AO-CRCs. Aggressive treatment regimens based solely on the age at CRC diagnosis are not warranted.

Early TP53 Alterations Shape Gastric and Esophageal Cancer Development

Gastric and esophageal (GE) adenocarcinomas are the third and sixth most common causes of cancer-related mortality worldwide, accounting for greater than 1.25 million annual deaths. Despite the advancements in the multi-disciplinary treatment approaches, the prognosis for patients with GE adenocarcinomas remains poor, with a 5-year survival of 32% and 19%, respectively, mainly due to the late-stage diagnosis and aggressive nature of these cancers. Premalignant lesions characterized by atypical glandular proliferation, with neoplastic cells confined to the basement membrane, often precede malignant disease. We now appreciate that premalignant lesions also carry cancer-associated mutations, enabling disease progression in the right environmental context. A better understanding of the premalignant-to-malignant transition can help us diagnose, prevent, and treat GE adenocarcinoma. Here, we discuss the evidence suggesting that alterations in TP53 occur early in GE adenocarcinoma evolution, are selected for under environmental stressors, are responsible for shaping the genomic mechanisms for pathway dysregulation in cancer progression, and lead to potential vulnerabilities that can be exploited by a specific class of targeted therapy.