A phase II study of guadecitabine combined with irinotecan vs regorafenib or TAS-102 in irinotecan-refractory metastatic colorectal cancer patients

DNA methyltransferase inhibitors (DNMTi) have demonstrated benefit in reversing resistance to systemic therapies for several cancer types. In a phase II trial of guadecitabine and irinotecan compared to regorafenib or TAS-102 in pts with advanced mCRC refractory to irinotecan. Patients with mCRC refractory to irinotecan were randomized 2:1 to guadecitabine and irinotecan (Arm A) vs standard of care regorafenib or TAS-102 (Arm B) on a 28-day cycle. Between January 15, 2016 and October 24, 2018, 104 pts were randomized at four international sites, with 96 pts undergoing treatment, 62 in Arm A and 34 in Arm B. Median overall survival was 7.15 months for Arm A and 7.66 months for Arm B (HR 0.93, 95% CI: 0.58-1.47, P = .75). The Kaplan-Meier rates of progression free survival at 4 months were 32% in Arm A and 26% in Arm B. Common ≥Grade 3 treatment related adverse events in Arm A were neutropenia (42%), anemia (18%), diarrhea (11%), compared to Arm B pts with neutropenia (12%), anemia (12%). Guadecitabine and irinotecan had similar OS compared to standard of care TAS-102 or regorafenib, with evidence of target modulation. Clinical trial information: NCT01896856.

Early-Onset Colorectal Cancer Patients Do Not Require Shorter Intervals for Post-Surgical Surveillance Colonoscopy

BACKGROUND

Early-onset colorectal cancer (EO-CRC), diagnosed before age 50, is rising in incidence worldwide. Although post-surgical colonoscopy surveillance strategies exist, appropriate intervals in EO-CRC remain elusive, as long-term surveillance outcomes remain scant. We sought to compare findings of surveillance colonoscopies of EO-CRC to average onset colorectal cancer (AO-CRC) patients to help define surveillance outcomes in these groups.

METHODS

Single institution retrospective chart review identified EO-CRC and AO-CRC patients with colonoscopy and no evidence of disease. Surveillance intervals and time to development of advanced neoplasia (CRC and advanced polyps (adenoma/sessile serrated)) were examined. For each group, three serial surveillance colonoscopies were evaluated. Statistical analyses were performed utilizing log-ranked Kaplan-Meier method and Cox proportional hazards.

RESULTS

A total of 1259 CRC patients were identified, with 612 and 647 patients in the EO-CRC and AO-CRC groups, respectively. Compared to AO-CRC patients, EO-CRC patients had a 29% decreased risk of developing advanced neoplasia from time of initial surgery to first surveillance colonoscopy (HR=0.71, 95% CI 0.52 - 1.0). Average follow-up time from surgical resection to first surveillance colonoscopy was 12.6 months for both cohorts. Overall surveillance findings differed between cohorts (p=0.003), and EO-CRC were found to have less advanced neoplasia compared to AO-CRC counterparts (12.4% vs 16.0%, respectively). Subsequent colonoscopies found that while EO-CRC patients returned for follow-up surveillance colonoscopy earlier than AO-CRC patients, the EO-CRC cohort did not have more advanced neoplasia nor non-advanced adenomas.

CONCLUSIONS

EO-CRC patients do not have an increased risk of advanced neoplasia compared to AO-CRC patients and therefore do not require more frequent colonoscopy surveillance than current guidelines recommend.

Immune checkpoint inhibitor therapy in locally advanced MSI GI malignancies

Locally advanced gastrointestinal (GI) malignancies have conventionally been treated in a multimodal fashion that combines (neo)adjuvant chemotherapy with or without radiation and definitive surgical resection. Clinical data have demonstrated the reduced responsiveness of GI malignancies with microsatellite instability (MSI) to both adjuvant and neoadjuvant systemic chemotherapy when compared with microsatellite stable (MSS) disease. The elevated tumor mutational burden associated with MSI tumors of all types sensitizes these tumors to the effects of immune checkpoint blockade in the metastatic setting, which led to tumor-agnostic approval of immune checkpoint inhibitors in this context. The recent demonstration of greater sensitivity and high pathologic complete response rates to neoadjuvant immunotherapy in locally advanced GI malignancies may ultimately establish a novel treatment paradigm and herald potential nonoperative management of this distinct subgroup of GI malignancies. This article provides an overview of immune checkpoint inhibitor therapy in locally advanced MSI GI malignancies. It also covers the clinical significance of MSI status across the GI cancer spectrum, the available data demonstrating differential responses of MSI and MSS disease to conventional chemotherapy, and the biological rationale for novel strategies utilizing immunotherapy in the neoadjuvant, adjuvant, and nonoperative settings.

Oncologic Outcomes of Salvage Abdominoperineal Resection for Anal Squamous Cell Carcinoma Initially Managed with Chemoradiation

Background: Abdominoperineal resection (APR) has been advocated for persistent or recurrent disease after failure of chemoradiation (CRT) for anal squamous cell cancer (SCC). Treatment with salvage APR can potentially achieve a cure. This study aimed to analyze oncological outcomes for salvage APR in a recent time period at a comprehensive cancer center. Methods: A retrospective review of all patients who underwent APR for biopsy-proven persistent or recurrent anal SCC between 1 January 2007 and 31 December 2020 was performed. Patients with stage IV disease at the time of initial diagnosis and patients with missing data were excluded. Univariate analysis was used with a chi-square test for categorical variables, and non-parametric tests were used for continuous variables. Kaplan-Meier survival analysis was performed to evaluate disease-specific (DSS), post-APR local recurrence-free (RFS), and disease-free survival (DFS). Results: A total of 96 patients were included in the analysis: 39 (41%) with persistent disease and 57 (59%) with recurrent SCC after chemoradiation had been completed. The median follow-up was 22 months (IQR 11-47). Forty-nine patients (51%) underwent extended APR and/or pelvic exenteration. Eight (8%) patients developed local recurrence, 30 (31%) developed local and distant recurrences, and 16 (17%) developed distant recurrences alone. The 3-year DSS, post-APR local recurrence-free survival, and disease-free survival were 53.8% (95% CI 43.5-66.5%), 54.5% (95% CI 44.4-66.8%), and 26.8% (95% CI 18.6-38.7%), respectively. In multivariate logistic regression analysis, positive microscopic margin (OR 10.0, 95% CI 2.16-46.12, p = 0.003), positive nodes in the surgical specimen (OR 9.19, 95% CI 1.99-42.52, p = 0.005), and lymphovascular invasion (OR 2.61 95% CI 1.05-6.51, p = 0.04) were associated with recurrence of disease. Gender, indication for APR (recurrent vs. persistent disease), HIV status, extent of surgery, or type of reconstruction did not influence survival outcomes. Twenty patients had targeted tumor-sequencing data available. Nine patients had PIK3CA mutations, seven of whom experienced a recurrence. Conclusions: Salvage APR for anal SCC after failed CRT was associated with poor disease-specific survival and low recurrence-free survival. Anal SCC patients undergoing salvage APR should be counseled that microscopic positive margins, positive lymph nodes, or the presence of lymphovascular invasion in the APR specimen are prognosticators for disease relapse. Our results accentuate the necessity for additional treatment strategies for the ongoing treatment challenge of persistent or recurrent anal SCC after failed CRT.

Molecular and Clinical Determinants of Acquired Resistance and Treatment Duration for Targeted Therapies in Colorectal Cancer

PURPOSE

Targeted therapies have improved outcomes for patients with metastatic colorectal cancer, but their impact is limited by rapid emergence of resistance. We hypothesized that an understanding of the underlying genetic mechanisms and intrinsic tumor features that mediate resistance to therapy will guide new therapeutic strategies and ultimately allow the prevention of resistance.

EXPERIMENTAL DESIGN

We assembled a series of 52 patients with paired pre-treatment and progression samples who received therapy targeting EGFR (n=17), BRAF V600E (n=17), KRAS G12C (n=15), or amplified HER2 (n=3) to identify molecular and clinical factors associated with time on treatment (TOT).

RESULTS

All patients stopped treatment for progression and TOT did not vary by oncogenic driver (p=0.5). Baseline disease burden (≥3 versus <3 sites, p=0.02), the presence of hepatic metastases (p=0.02), and gene amplification on baseline tissue (p=0.03) were each associated with shorter TOT. We found evidence of chromosomal instability (CIN) at progression in patients with baseline MAPK pathway amplifications and those with acquired gene amplifications. At resistance, copy number changes (p=0.008) and high number (≥5) of acquired alterations (p=0.04) were associated with shorter TOT. Patients with hepatic metastases demonstrated both higher number of emergent alterations at resistance and enrichment of mutations involving receptor tyrosine kinases.

CONCLUSIONS

Our genomic analysis suggests that high baseline CIN or effective induction of enhanced mutagenesis on targeted therapy underlies rapid progression. Longer response appears to result from a progressive acquisition of genomic or chromosomal instability in the underlying cancer or from the chance event of a new resistance alteration.

Long-Term Results of Organ Preservation in Patients With Rectal Adenocarcinoma Treated With Total Neoadjuvant Therapy: The Randomized Phase II OPRA Trial

Clinical trials frequently include multiple end points that mature at different times. The initial report, typically based on the primary end point, may be published when key planned co-primary or secondary analyses are not yet available. Clinical Trial Updates provide an opportunity to disseminate additional results from studies, published in JCO or elsewhere, for which the primary end point has already been reported.To assess long-term risk of local tumor regrowth, we report updated organ preservation rate and oncologic outcomes of the OPRA trial (ClinicalTrials.gov identifier: NCT02008656). Patients with stage II/III rectal cancer were randomly assigned to receive induction chemotherapy followed by chemoradiation (INCT-CRT) or chemoradiation followed by consolidation chemotherapy (CRT-CNCT). Patients who achieved a complete or near-complete response after finishing treatment were offered watch-and-wait (WW). Total mesorectal excision (TME) was recommended for those who achieved an incomplete response. The primary end point was disease-free survival (DFS). The secondary end point was TME-free survival. In total, 324 patients were randomly assigned (INCT-CRT, n = 158; CRT-CNCT, n = 166). Median follow-up was 5.1 years. The 5-year DFS rates were 71% (95% CI, 64 to 79) and 69% (95% CI, 62 to 77) for INCT-CRT and CRT-CNCT, respectively (P = .68). TME-free survival was 39% (95% CI, 32 to 48) in the INCT-CRT group and 54% (95% CI, 46 to 62) in the CRT-CNCT group (P = .012). Of 81 patients with regrowth, 94% occurred within 2 years and 99% occurred within 3 years. DFS was similar for patients who underwent TME after restaging (64% [95% CI, 53 to 78]) and patients in WW who underwent TME after regrowth (64% [95% CI, 53 to 78]; P = .94). Updated analysis continues to show long-term organ preservation in half of the patients with rectal cancer treated with total neoadjuvant therapy. In patients who enter WW, most cases of tumor regrowth occur in the first 2 years.

Clinical and molecular characteristics of early-onset vs average-onset esophagogastric cancer

BACKGROUND

The rate of esophagogastric cancer is rising among individuals under 50 years of age. It remains unknown whether early-onset esophagogastric cancer represents a unique entity. This study investigated the clinical and molecular characteristics of early-onset and average-onset esophagogastric cancer .

METHODS

We reviewed the Memorial Sloan Kettering Cancer Center gastric, esophageal, and gastroesophageal junction cancer database. Associations between baseline characteristics and tumor and germline molecular alterations were compared between those with early-onset and average-onset esophagogastric cancer using Fisher exact tests and the Benjamini-Hochberg method for multiple-hypothesis correction.

RESULTS

We included 1123 patients with early-onset esophagogastric cancer (n = 219; median age = 43 years [range = 18-49 years]) and average-onset esophagogastric cancer (n = 904; median age = 67 years [range = 50-94 years]) treated between 2005 and 2018. The early-onset group had more women (39% vs 28%, P = .002). Patients with early-onset esophagogastric cancer were more likely to have a gastric primary site (64% vs 44%, P < .0001). The signet ring cell and/or diffuse type was 3 times more common in the early-onset esophagogastric cancer group (31% vs 9%, P < .0001). Early-onsite tumors were more frequently genomically stable (31% vs 18%, P = .0002) and unlikely to be microsatellite instability high (2% vs 7%, P = .003). After restricting to adenocarcinoma and signet ring cell and/or diffuse type carcinomas, we observed no difference in stage (P = .40) or overall survival from stage IV diagnosis (median = 22.7 vs 22.1 months, P = .78).

CONCLUSIONS

Our study supported a preponderance of gastric primary disease sites, signet ring histology, and genomically stable molecular subtypes in early-onset esophagogastric cancer. Our findings highlight the need for further research to define the underlying pathogenesis and strategies for early detection and prevention.

Concordance in Oncogenic Alterations Between the Primary Tumor and Advanced Disease: Insights Into the Heterogeneity of Intrahepatic Cholangiocarcinoma

PURPOSE

Intrahepatic cholangiocarcinoma (ICCA) is characterized by significant phenotypic and clinical heterogeneities and poor response to systemic therapy, potentially related to underlying heterogeneity in oncogenic alterations. We aimed to characterize the genomic heterogeneity between primary tumors and advanced disease in patients with ICCA.

METHODS

Biopsy-proven CCA specimens (primary tumor and paired advanced disease [metastatic disease, progressive disease on systemic therapy, or postoperative recurrence]) from two institutions were subjected to targeted next-generation sequencing. Overall concordance (oncogenic driver mutations, copy number alterations, and fusion events) and mutational concordance (only oncogenic mutations) were compared across paired samples. A subgroup analysis was performed on the basis of exposure to systemic therapy. Patients with extrahepatic CCA (ECCA) were included as a comparison group.

RESULTS

Sample pairs from 65 patients with ICCA (n = 54) and ECCA (n = 11) were analyzed. The median time between sample collection was 19.6 months (range, 2.7-122.9). For the entire cohort, the overall oncogenic concordance was 49% and the mutational concordance was 62% between primary and advanced disease samples. Subgroup analyses of ICCA and ECCA revealed overall/mutational concordance rates of 47%/58% and 60%/84%, respectively. Oncogenic concordance was similarly low for pairs exposed to systemic therapy between sample collections (n = 50, 53% overall, 68% mutational). In patients treated with targeted therapy for IDH1/2 alterations (n = 6) or FGFR2 fusions (n = 3), there was 100% concordance between the primary and advanced disease specimens. In two patients, FGFR2 (n = 1) and IDH1 (n = 1) alterations were detected de novo in the advanced disease specimens.

CONCLUSION

The results reflect a high degree of heterogeneity in ICCA and argue for reassessment of the dominant driver mutations with change in disease status.

Case-Based Clinical Guidance on Dosing and Management of the Hepatic Artery Infusion Chemotherapy Pump

Hepatic artery infusion (HAI) delivers localized high-dose floxuridine directly to liver tumors through an implanted pump. While patients are undergoing active treatment, the pump is refilled with chemotherapy alternating with saline every 2 weeks using a specialized noncoring needle. Numerous clinical scenarios influence the dosing of floxuridine, which do not conform to the usual dose modification schema for systemic chemotherapy. This article aims to provide practical clinical management solutions to overcome the common challenges faced by oncologists in the real-world management of HAI pump therapy.

Gemcitabine with Cisplatin Versus Hepatic Arterial Infusion Pump Chemotherapy for Liver-Confined Unresectable Intrahepatic Cholangiocarcinoma

BACKGROUND

A post-hoc analysis of ABC trials included 34 patients with liver-confined unresectable intrahepatic cholangiocarcinoma (iCCA) who received systemic chemotherapy with gemcitabine and cisplatin (gem-cis). The median overall survival (OS) was 16.7 months and the 3-year OS was 2.8%. The aim of this study was to compare patients treated with systemic gem-cis versus hepatic arterial infusion pump (HAIP) chemotherapy for liver-confined unresectable iCCA.

METHODS

We retrospectively collected consecutive patients with liver-confined unresectable iCCA who received gem-cis in two centers in the Netherlands to compare with consecutive patients who received HAIP chemotherapy with or without systemic chemotherapy in Memorial Sloan Kettering Cancer Center.

RESULTS

In total, 268 patients with liver-confined unresectable iCCA were included; 76 received gem-cis and 192 received HAIP chemotherapy. In the gem-cis group 42 patients (55.3%) had multifocal disease compared with 141 patients (73.4%) in the HAIP group (p = 0.023). Median OS for gem-cis was 11.8 months versus 27.7 months for HAIP chemotherapy (p < 0.001). OS at 3 years was 3.5% (95% confidence interval [CI] 0.0-13.6%) in the gem-cis group versus 34.3% (95% CI 28.1-41.8%) in the HAIP chemotherapy group. After adjusting for male gender, performance status, baseline hepatobiliary disease, and multifocal disease, the hazard ratio (HR) for HAIP chemotherapy was 0.27 (95% CI 0.19-0.39).

CONCLUSIONS

This study confirmed the results from the ABC trials that survival beyond 3 years is rare for patients with liver-confined unresectable iCCA treated with palliative gem-cis alone. With HAIP chemotherapy, one in three patients was alive at 3 years.

Pharmaceutical Agents as Potential Drivers in the Development of Early-Onset Colorectal Cancer: Case-Control Study

BACKGROUND

The incidence of early-onset colorectal cancer (EOCRC) rose abruptly in the mid 1990s, is continuing to increase, and has now been noted in many countries. By 2030, 25% of American patients diagnosed with rectal cancer will be 49 years or younger. The large majority of EOCRC cases are not found in patients with germline cancer susceptibility mutations (eg, Lynch syndrome) or inflammatory bowel disease. Thus, environmental or lifestyle factors are suspected drivers. Obesity, sedentary lifestyle, diabetes mellitus, smoking, alcohol, or antibiotics affecting the gut microbiome have been proposed. However, these factors, which have been present since the 1950s, have not yet been conclusively linked to the abrupt increase in EOCRC. The sharp increase suggests the introduction of a new risk factor for young people. We hypothesized that the driver may be an off-target effect of a pharmaceutical agent (ie, one requiring regulatory approval before its use in the general population or an off-label use of a previously approved agent) in a genetically susceptible subgroup of young adults. If a pharmaceutical agent is an EOCRC driving factor, regulatory risk mitigation strategies could be used.

OBJECTIVE

We aimed to evaluate the possibility that pharmaceutical agents serve as risk factors for EOCRC.

METHODS

We conducted a case-control study. Data including demographics, comorbidities, and complete medication dispensing history were obtained from the electronic medical records database of Maccabi Healthcare Services, a state-mandated health provider covering 26% of the Israeli population. The participants included 941 patients with EOCRC (≤50 years of age) diagnosed during 2001-2019 who were density matched at a ratio of 1:10 with 9410 control patients. Patients with inflammatory bowel disease and those with a known inherited cancer susceptibility syndrome were excluded. An advanced machine learning algorithm based on gradient boosted decision trees coupled with Bayesian model optimization and repeated data sampling was used to sort through the very high-dimensional drug dispensing data to identify specific medication groups that were consistently linked with EOCRC while allowing for synergistic or antagonistic interactions between medications. Odds ratios for the identified medication classes were obtained from a conditional logistic regression model.

RESULTS

Out of more than 800 medication classes, we identified several classes that were consistently associated with EOCRC risk across independently trained models. Interactions between medication groups did not seem to substantially affect the risk. In our analysis, drug groups that were consistently positively associated with EOCRC included beta blockers and valerian (Valeriana officinalis). Antibiotics were not consistently associated with EOCRC risk.

CONCLUSIONS

Our analysis suggests that the development of EOCRC may be correlated with prior use of specific medications. Additional analyses should be used to validate the results. The mechanism of action inducing EOCRC by candidate pharmaceutical agents will then need to be determined.

Combined Hepatic Arterial Infusion Pump and Systemic Chemotherapy in the Modern Era for Chemotherapy-Naive Patients with Unresectable Colorectal Liver Metastases

PURPOSE

Chemotherapy-naive patients with unresectable colorectal liver metastases (CRLM) have been the best responders to hepatic arterial infusion (HAI) therapy. The current treatment paradigm has drifted away from HAI in the first-line setting. We aimed to analyze outcomes of combined first-line systemic therapy with HAI therapy (HAI+SYS) in the modern era.

METHODS

We conducted a retrospective study of consecutive chemotherapy-naive patients with unresectable CRLM who received HAI+SYS between 2003 and 2019. Patients were selected from a prospectively maintained database. Outcomes included radiological response rate, conversion to resection (CTR) rate, and overall survival (OS).

RESULTS

Fifty-eight chemotherapy-naive patients were identified out of 546 patients with unresectable CRLM managed with HAI. After induction treatment, 4 patients (7%) had a complete radiological response, including two durable responses. In total, 32 patients (55%) underwent CTR. CTR or complete response without resection was achieved after seven cycles of systemic therapy and four cycles of HAI therapy. Median OS for the whole cohort was 53.0 months (95% confidence interval 23.0-82.9). Three- and 5-year OS in patients who achieved CTR or complete response versus patients who did not was 88% and 72% versus 27% and 0% respectively. Of patients who underwent CTR, complete and major pathological response (no and <10% viable tumor cells, respectively) was observed in 7 (22%) and 12 patients (38%).

CONCLUSIONS

Combined HAI+SYS in chemotherapy-naive patients resulted in durable and substantial response in a large proportion of patients. Nearly two-thirds of patients achieved a complete response or proceeded to conversion surgery, which was associated with prolonged survival.

Neoplasia risk in patients with Lynch syndrome treated with immune checkpoint blockade

Metastatic and localized mismatch repair-deficient (dMMR) tumors are exquisitely sensitive to immune checkpoint blockade (ICB). The ability of ICB to prevent dMMR malignant or pre-malignant neoplasia development in patients with Lynch syndrome (LS) is unknown. Of 172 cancer-affected patients with LS who had received ≥1 ICB cycles, 21 (12%) developed subsequent malignancies after ICB exposure, 91% (29/32) of which were dMMR, with median time to development of 21 months (interquartile range, 6-38). Twenty-four of 61 (39%) ICB-treated patients who subsequently underwent surveillance colonoscopy had premalignant polyps. Within matched pre-ICB and post-ICB follow-up periods, the overall rate of tumor development was unchanged; however, on subgroup analysis, a decreased incidence of post-ICB visceral tumors was observed. These data suggest that ICB treatment of LS-associated tumors does not eliminate risk of new neoplasia development, and LS-specific surveillance strategies should continue. These data have implications for immunopreventative strategies and provide insight into the immunobiology of dMMR tumors.

Efficacy of HER2-Targeted Intraperitoneal 225Ac α-Pretargeted Radioimmunotherapy for Small-Volume Ovarian Peritoneal Carcinomatosis

Epithelial ovarian cancer (EOC) is often asymptomatic and presents clinically in an advanced stage as widespread peritoneal microscopic disease that is generally considered to be surgically incurable. Targeted α-therapy with the α-particle-emitting radionuclide 225Ac (half-life, 9.92 d) is a high-linear-energy-transfer treatment approach effective for small-volume disease and even single cells. Here, we report the use of human epidermal growth factor receptor 2 (HER2) 225Ac-pretargeted radioimmunotherapy (PRIT) to treat a mouse model of human EOC SKOV3 xenografts growing as peritoneal carcinomatosis (PC). Methods: On day 0, 105 SKOV3 cells transduced with a luciferase reporter gene were implanted intraperitoneally in nude mice, and tumor engraftment was verified by bioluminescent imaging (BLI). On day 15, treatment was started using 1 or 2 cycles of 3-step anti-HER2 225Ac-PRIT (37 kBq/cycle as 225Ac-Proteus DOTA), separated by a 1-wk interval. Efficacy and toxicity were monitored for up to 154 d. Results: Untreated PC-tumor-bearing nude mice showed a median survival of 112 d. We used 2 independent measures of response to evaluate the efficacy of 225Ac-PRIT. First, a greater proportion of the treated mice (9/10 1-cycle and 8/10 2-cycle; total, 17/20; 85%) survived long-term compared with controls (9/27, 33%), and significantly prolonged survival was documented (log-rank [Mantel-Cox] P = 0.0042). Second, using BLI, a significant difference in the integrated BLI signal area to 98 d was noted between controls and treated groups (P = 0.0354). Of a total of 8 mice from the 2-cycle treatment group (74 kBq total) that were evaluated by necropsy, kidney radiotoxicity was mild and did not manifest itself clinically (normal serum blood urea nitrogen and creatinine). Dosimetry estimates (relative biological effectiveness-weighted dose, where relative biological effectiveness = 5) per 37 kBq administered for tumors and kidneys were 56.9 and 16.1 Gy, respectively. One-cycle and 2-cycle treatments were equally effective. With immunohistology, mild tubular changes attributable to α-toxicity were observed in both therapeutic groups. Conclusion: Treatment of EOC PC-tumor-bearing mice with anti-HER2 225Ac-PRIT resulted in histologic cures and prolonged survival with minimal toxicity. Targeted α-therapy using the anti-HER2 225Ac-PRIT system is a potential treatment for otherwise incurable EOC.

The Impact of Germline Alterations in Appendiceal Adenocarcinoma

PURPOSE

More than 10% of assessed patients with appendiceal adenocarcinoma have a pathogenic (P) or likely pathogenic (LP) germline variant, including genes implicated in heritable gastrointestinal cancer syndromes, such as Lynch syndrome. We defined the clinical and molecular impact of heritable alterations in appendiceal adenocarcinoma to evaluate the need for dedicated appendiceal screening and prevention strategies in patients with LP/P germline variants.

EXPERIMENTAL DESIGN

We performed an integrated germline and somatic molecular analysis for patients with confirmed appendiceal adenocarcinoma. Patients underwent paired tumor-normal sequencing for up to 90 hereditary cancer risk genes and 505 genes for somatic mutation profiling. We defined the cooccurrence of LP/P germline variants and second-hit pathogenic somatic alterations. The associations between germline variants and patient clinicopathologic features were also evaluated.

RESULTS

Twenty-five of 237 patients (10.5%) carried pathogenic or likely pathogenic germline variants in cancer susceptibility genes. Clinicopathologic characteristics and appendiceal adenocarcinoma-specific survival were similar in patients with or without germline variants. Most (92%, N = 23/25) patients with germline variants demonstrated no second-hit somatic alterations, including loss of heterozygosity. Two patients with a germline APC I1307K low-penetrance founder variant exhibited secondary somatic pathogenic alterations in APC. However, only one patient tumor exhibited APC-mediated WNT signaling dysregulation: a plausible consequence of multiple somatic APC mutations with no germline variant contribution. Four patients had germline variants in PMS2 or MSH2 associated with Lynch syndrome, yet their cancers were microsatellite-stable.

CONCLUSIONS

Germline variants are likely incidental without a contributory driver role in appendiceal adenocarcinoma. Appendiceal adenocarcinoma screening in patients with germline variants is not clearly merited.

Prevalence and Clinical Implications of Mismatch Repair-Proficient Colorectal Cancer in Patients With Lynch Syndrome

PURPOSE

Lynch syndrome (LS)-associated colorectal cancer (CRC) is characterized by mismatch repair-deficiency (MMR-D) and/or microsatellite instability (MSI). However, with increasing utilization of germline testing, MMR-proficient (MMR-P) and/or microsatellite stable (MSS) CRC has also been observed. We sought to characterize MMR-P/MSS CRC among patients with LS.

METHODS

Patients with solid tumors with germline MMR pathogenic/likely pathogenic (P/LP) variants were identified on a prospective matched tumor-normal next-generation sequencing (NGS) protocol. CRCs were evaluated for MMR-D via immunohistochemical (IHC) staining and/or MSI via NGS. Clinical variables were correlated with MMR status using nonparametric tests.

RESULTS

Among 17,617 patients with solid tumors, 1.4% (n = 242) had LS. A total of 36% (86 of 242) of patients with LS had at least one CRC that underwent NGS profiling, amounting to 99 pooled CRCs assessed. A total of 10% (10 of 99) of CRCs were MMR-P, with 100% concordance between MSS status and retained MMR protein staining. A total of 89% (8 of 9) of patients in the MMR-P group had MSH6 or PMS2 variants, compared with 30% (23 of 77) in the MMR-D group (P = .001). A total of 46% (6 of 13) of PMS2+ patients had MMR-P CRC. The median age of onset was 58 and 43 years for MMR-P and MMR-D CRC, respectively (P = .07). Despite the later median age of onset, 40% (4 of 10) of MMR-P CRCs were diagnosed <50. A total of 60% (6 of 10) of MMR-P CRCs were metastatic compared with 13% (12 of 89) of MMR-D CRCs (P = .002). A total of 33% (3 of 9) of patients with MMR-P CRC did not meet LS testing criteria.

CONCLUSION

Patients with LS remained at risk for MMR-P CRC, which was more prevalent among patients with MSH6 and PMS2 variants. MMR-P CRC was later onset and more commonly metastatic compared with MMR-D CRC. Confirmation of tumor MMR/MSI status is critical for patient management and familial risk estimation.

Tucatinib plus trastuzumab for chemotherapy-refractory, HER2-positive, RAS wild-type unresectable or metastatic colorectal cancer (MOUNTAINEER): a multicentre, open-label, phase 2 study

BACKGROUND

HER2 is an actionable target in metastatic colorectal cancer. We assessed the activity of tucatinib plus trastuzumab in patients with chemotherapy-refractory, HER2-positive, RAS wild-type unresectable or metastatic colorectal cancer.

METHODS

MOUNTAINEER is a global, open-label, phase 2 study that enrolled patients aged 18 years and older with chemotherapy-refractory, HER2-positive, RAS wild-type unresectable or metastatic colorectal cancer at 34 sites (clinics and hospitals) in five countries (Belgium, France, Italy, Spain, and the USA). Initially, the study was designed as a single-cohort study, which was expanded following an interim analysis to include more patients. Initially, patients were given tucatinib (300 mg orally twice daily) plus intravenous trastuzumab (8 mg/kg as an initial loading dose, then 6 mg/kg every 21 days; cohort A) for the duration of treatment (until progression), and after expansion, patients were randomly assigned (4:3), using an interactive web response system and stratified by primary tumour location, to either tucatinib plus trastuzumab (cohort B) or tucatinib monotherapy (cohort C). The primary endpoint was confirmed objective response rate per blinded independent central review (BICR) for cohorts A and B combined and was assessed in patients in the full analysis set (ie, patients with HER2-positive disease who received at least one dose of study treatment). Safety was assessed in all patients who received at least one dose of study treatment. This trial is registered with ClinicalTrials.gov, NCT03043313, and is ongoing.

FINDINGS

Between Aug 8, 2017, and Sept 22, 2021, 117 patients were enrolled (45 in cohort A, 41 in cohort B, and 31 in cohort C), of whom 114 patients had locally assessed HER2-positive disease and received treatment (45 in cohort A, 39 in cohort B, and 30 in cohort C; full analysis set), and 116 patients received at least one dose of study treatment (45 in cohort A, 41 in cohort B, and 30 in cohort C; safety population). In the full analysis set, median age was 56·0 years (IQR 47-64), 66 (58%) were male, 48 (42%) were female, 88 (77%) were White, and six (5%) were Black or African American. As of data cutoff (March 28, 2022), in 84 patients from cohorts A and B in the full analysis set, the confirmed objective response rate per BICR was 38·1% (95% CI 27·7-49·3; three patients had a complete response and 29 had a partial response). In cohorts A and B, the most common adverse event was diarrhoea (55 [64%] of 86), the most common grade 3 or worse adverse event was hypertension (six [7%] of 86), and three (3%) patients had tucatinib-related serious adverse events (acute kidney injury, colitis, and fatigue). In cohort C, the most common adverse event was diarrhoea (ten [33%] of 30), the most common grade 3 or worse adverse events were increased alanine aminotransferase and aspartate aminotransferase (both two [7%]), and one (3%) patient had a tucatinib-related serious adverse event (overdose). No deaths were attributed to adverse events. All deaths in treated patients were due to disease progression.

INTERPRETATION

Tucatinib plus trastuzumab had clinically meaningful anti-tumour activity and favourable tolerability. This treatment is the first US Food and Drug Administration-approved anti-HER2 regimen for metastatic colorectal cancer and is an important new treatment option for chemotherapy-refractory HER2-positive metastatic colorectal cancer.

FUNDING

Seagen and Merck & Co.

Incomplete cytoreductive surgery for appendiceal and colorectal peritoneal carcinomatosis: Characteristics and outcomes of an overlooked group

BACKGROUND OND OBJECTIVES

Complete cytoreductive surgery (CRS) may prolong survival for selected patients with peritoneal carcinomatosis from colorectal cancer (CRC). However, there is a paucity of data on outcomes following incomplete procedures.

METHODS

Patients with incomplete CRS for well-differentiated (WD) and moderate/poorly-differentiated (M/PD) appendiceal cancer, right and left CRC were identified at a single tertiary center (2008-2021).

RESULTS

Of 109 patients, 10% were WD and 51% M/PD appendiceal cancers, and 16% right and 23% left CRC. There were no differences in gender, BMI (mean = 27), ASA score, previous abdominal surgery (72%), and extent of CRS. The PC Index differed between appendiceal and colorectal cancers (mean = 27 vs. 17, p < 0.01). Overall, the perioperative outcomes were similar among the groups, with 15% experiencing complications. Postoperatively, 61% received chemotherapy, and 51% required ≥1 subsequent procedure. The 1 and 3-year survival for the WD, M/PD, right and left CRC subgroups were 100%, 67%, 44%, 51%, and 88%, 17%, 12%, and 23%, respectively (p = 0.02).

CONCLUSIONS

Incomplete CRS was associated with significant morbidity and number of subsequent palliative procedures. Prognosis correlated with histologic subtype; WD appendiceal cancer patients having superior outcomes, while those with right sided CRC the worst survival. These data may help guiding expectations in the setting of incomplete procedures.

Hepatic disease control in patients with intrahepatic cholangiocarcinoma correlates with overall survival

PURPOSE

The role of locoregional therapy compared to systemic chemotherapy (SYS) for unresectable intrahepatic cholangiocarcinoma (IHC) remains controversial. The importance of hepatic disease control, either as initial or salvage therapy, is also unclear. We compared overall survival (OS) in patients treated with resection, hepatic arterial infusion pump (HAIP) chemotherapy, or SYS as it relates to hepatic recurrence or progression. We also evaluated recurrence after resection to determine the efficacy of locoregional salvage therapy.

PATIENTS AND METHODS

In this single-institution retrospective analysis, patients with biopsy-proven IHC treated with either curative-intent resection, HAIP (with or without SYS), or SYS alone were analyzed. Propensity score matching (PSM) was used to compare patients with liver-limited, advanced disease treated with HAIP versus SYS. The impact of locoregional salvage therapies in patients with liver-limited recurrence was analyzed in the resection cohort.

RESULTS

From 2000 to 2017, 714 patients with IHC were treated, 219 (30.7%) with resectable disease, 316 (44.3%) with locally advanced disease, and 179 (25.1%) with metastatic disease. Resected patients were less likely to recur or progress in the liver (hazard ratio [HR] 0.41, 95% CI 0.34-0.45) versus those that received HAIP or SYS (HR 0.58, 95% CI 0.50-0.65 vs. HR 0.63, 95% CI 0.57-0.69, respectively). In resected patients, 161 (64.4%) recurred, with 65 liver-only recurrences. Thirty of these patients received subsequent locoregional therapy. On multivariable analysis, locoregional therapy was associated with improved OS after isolated liver recurrence (HR 0.46, 95% CI 0.29-0.75; p = 0.002). In patients with locally advanced unresectable or multifocal liver disease (with or without distant organ metastases), PSM demonstrated improved hepatic progression-free survival in patients treated with HAIP versus SYS (HR 0.65; 95% CI 0.46-0.91; p = 0.01), which correlated with improved OS (HR 0.59, 95% CI 0.43-0.80; p < 0.001).

CONCLUSION

In patients with liver-limited IHC, hepatic disease control is associated with improved OS, emphasizing the potential importance of liver-directed therapy.

Molecular Classification of Appendiceal Adenocarcinoma

PURPOSE

Appendiceal adenocarcinomas (ACs) are rare, histologically diverse malignancies treated as colorectal cancers despite having distinct biology and clinical behavior. To guide clinical decision making, we defined molecular subtypes of AC associated with patient survival, metastatic burden, and chemotherapy response.

PATIENTS AND METHODS

A comprehensive molecular analysis was performed in patients with AC to define molecular subtypes. Associations between molecular subtype and overall survival, intraoperative peritoneal cancer index, and first-line chemotherapy response were assessed adjusting for histopathologic and clinical variables using multivariable Cox proportional hazards, linear regression, and logistic regression models.

RESULTS

We defined distinct molecular lineages of mucinous appendiceal adenocarcinoma (MAAP) from co-occurring mutations in GNAS, RAS, and TP53. Of 164 MAAP tumors, 24 were RAS-mutant (mut) predominant (RAS-mut/GNAS-wild-type [wt]/TP53-wt) with significantly decreased mutations and chromosomal alterations compared with tumors with GNAS mutations (GNAS-mut predominant) or TP53 mutations (TP53-mut predominant). No patient with RAS-mut predominant subtype metastatic MAAP died of cancer, and overall survival in this subgroup was significantly improved compared with patients with GNAS-mut (P = .05) and TP53-mut (P = .004) predominant subtypes. TP53-mut predominant subtypes were highly aneuploid; increased tumor aneuploidy was independently (P = .001) associated with poor prognosis. The findings retained significance in patients with any metastatic AC. RAS-mut predominant metastases exhibited reduced peritoneal tumor bulk (P = .04) and stromal invasion (P < .001) compared with GNAS-mut or TP53-mut predominant tumors, respectively. Patients with RAS-mut predominant MAAP responded more to first-line chemotherapy (50%) compared with patients with GNAS-mut predominant tumors (6%, P = .03).

CONCLUSION

AC molecular patterns identify distinct molecular subtypes: a clinically indolent RAS-mut/GNAS-wt/TP53-wt subtype; a chemotherapy-resistant GNAS-mut predominant subtype; and an aggressive, highly aneuploid TP53-mut predominant subtype. Each subtype exhibits conserved clinical behavior irrespective of histopathology.

Delphi Initiative for Early-Onset Colorectal Cancer (DIRECt) International Management Guidelines

BACKGROUND & AIMS

Patients with early-onset colorectal cancer (eoCRC) are managed according to guidelines that are not age-specific. A multidisciplinary international group (DIRECt), composed of 69 experts, was convened to develop the first evidence-based consensus recommendations for eoCRC.

METHODS

After reviewing the published literature, a Delphi methodology was used to draft and respond to clinically relevant questions. Each statement underwent 3 rounds of voting and reached a consensus level of agreement of ≥80%.

RESULTS

The DIRECt group produced 31 statements in 7 areas of interest: diagnosis, risk factors, genetics, pathology-oncology, endoscopy, therapy, and supportive care. There was strong consensus that all individuals younger than 50 should undergo CRC risk stratification and prompt symptom assessment. All newly diagnosed eoCRC patients should receive germline genetic testing, ideally before surgery. On the basis of current evidence, endoscopic, surgical, and oncologic treatment of eoCRC should not differ from later-onset CRC, except for individuals with pathogenic or likely pathogenic germline variants. The evidence on chemotherapy is not sufficient to recommend changes to established therapeutic protocols. Fertility preservation and sexual health are important to address in eoCRC survivors. The DIRECt group highlighted areas with knowledge gaps that should be prioritized in future research efforts, including age at first screening for the general population, use of fecal immunochemical tests, chemotherapy, endoscopic therapy, and post-treatment surveillance for eoCRC patients.

CONCLUSIONS

The DIRECt group produced the first consensus recommendations on eoCRC. All statements should be considered together with the accompanying comments and literature reviews. We highlighted areas where research should be prioritized. These guidelines represent a useful tool for clinicians caring for patients with eoCRC.

Colorectal cancer statistics, 2023

Colorectal cancer (CRC) is the second most common cause of cancer death in the United States. Every 3 years, the American Cancer Society provides an update of CRC statistics based on incidence from population-based cancer registries and mortality from the National Center for Health Statistics. In 2023, approximately 153,020 individuals will be diagnosed with CRC and 52,550 will die from the disease, including 19,550 cases and 3750 deaths in individuals younger than 50 years. The decline in CRC incidence slowed from 3%-4% annually during the 2000s to 1% annually during 2011-2019, driven partly by an increase in individuals younger than 55 years of 1%-2% annually since the mid-1990s. Consequently, the proportion of cases among those younger than 55 years increased from 11% in 1995 to 20% in 2019. Incidence since circa 2010 increased in those younger than 65 years for regional-stage disease by about 2%-3% annually and for distant-stage disease by 0.5%-3% annually, reversing the overall shift to earlier stage diagnosis that occurred during 1995 through 2005. For example, 60% of all new cases were advanced in 2019 versus 52% in the mid-2000s and 57% in 1995, before widespread screening. There is also a shift to left-sided tumors, with the proportion of rectal cancer increasing from 27% in 1995 to 31% in 2019. CRC mortality declined by 2% annually from 2011-2020 overall but increased by 0.5%-3% annually in individuals younger than 50 years and in Native Americans younger than 65 years. In summary, despite continued overall declines, CRC is rapidly shifting to diagnosis at a younger age, at a more advanced stage, and in the left colon/rectum. Progress against CRC could be accelerated by uncovering the etiology of rising incidence in generations born since 1950 and increasing access to high-quality screening and treatment among all populations, especially Native Americans.

Clinical Outcomes Associated With Pembrolizumab Monotherapy Among Adults With Diffuse Malignant Peritoneal Mesothelioma

Importance

Diffuse malignant peritoneal mesothelioma (DMPM) represents a rare and clinically distinct entity among malignant mesotheliomas. Pembrolizumab has activity in diffuse pleural mesothelioma but limited data are available for DMPM; thus, DMPM-specific outcome data are needed.

Objective

To evaluate outcomes after the initiation of pembrolizumab monotherapy in the treatment of adults with DMPM.

Design, Setting, and Participants

This retrospective cohort study was conducted in 2 tertiary care academic cancer centers (University of Pennsylvania Hospital Abramson Cancer Center and Memorial Sloan Kettering Cancer Center). All patients with DMPM treated between January 1, 2015, and September 1, 2019, were retrospectively identified and followed until January 1, 2021. Statistical analysis was performed between September 2021 and February 2022.

Exposures

Pembrolizumab (200 mg or 2 mg/kg every 21 days).

Main Outcomes and Measures

Median progression-free survival (PFS) and median overall survival (OS) were assessed using Kaplan-Meier estimates. The best overall response was determined using RECIST (Response Evaluation Criteria in Solid Tumors) criteria, version 1.1. The association of disease characteristics with partial response was evaluated using the Fisher exact test.

Results

This study included 24 patients with DMPM who received pembrolizumab monotherapy. Patients had a median age of 62 years (IQR, 52.4-70.6 years); 14 (58.3%) were women, 18 (75.0%) had epithelioid histology, and most (19 [79.2%]) were White. A total of 23 patients (95.8%) received systemic chemotherapy prior to pembrolizumab, and the median number of lines of prior therapy was 2 (range, 0-6 lines). Of the 17 patients who underwent programmed death ligand 1 (PD-L1) testing, 6 (35.3%) had positive tumor PD-L1 expression (range, 1.0%-80.0%). Of the 19 evaluable patients, 4 (21.0%) had a partial response (overall response rate, 21.1% [95% CI, 6.1%-46.6%]), 10 (52.6%) had stable disease, and 5 (26.3%) had progressive disease (5 of 24 patients [20.8%] were lost to follow-up). There was no association between a partial response and the presence of a BAP1 alteration, PD-L1 positivity, or nonepithelioid histology. With a median follow-up of 29.2 (95% CI, 19.3 to not available [NA]) months, the median PFS was 4.9 (95% CI, 2.8-13.3) months and the median OS was 20.9 (95% CI, 10.0 to NA) months from pembrolizumab initiation. Three patients (12.5%) experienced PFS of more than 2 years. Among patients with nonepithelioid vs epithelioid histology, there was a numeric advantage in median PFS (11.5 [95% CI, 2.8 to NA] vs 4.0 [95% CI, 2.8-8.8] months) and median OS (31.8 [95% CI, 8.3 to NA] vs 17.5 [95% CI, 10.0 to NA] months); however, this did not reach statistical significance.

Conclusions and Relevance

The results of this retrospective dual-center cohort study of patients with DMPM suggest that pembrolizumab had clinical activity regardless of PD-L1 status or histology, although patients with nonepithelioid histology may have experienced additional clinical benefit. The partial response rate of 21.0% and median OS of 20.9 months in this cohort with 75.0% epithelioid histology warrants further investigation to identify those most likely to respond to immunotherapy.

HER2 testing in colorectal cancer: Concordance analysis between breast and gastric scoring algorithms from the MOUNTAINEER trial

198

Background: HER2 overexpression/amplification (HER2+) occurs in 3%-5% of patients (pts) w/ metastatic colorectal cancer (mCRC). Rates of HER2+ can increase to ~10% in pts w/ RAS/BRAF wild-type mCRC tumors. The MOUNTAINEER trial (NCT03043313) evaluated the efficacy and safety of the investigational combination of tucatinib with trastuzumab in pts with HER2+ and RAS wild-type mCRC. Established regional guidelines for mCRC recommend HER2 testing and HER2-directed treatment options; however, there is currently no established best practice for HER2 testing and interpretation in mCRC. Here, we present data from a concordance analysis comparing breast and gastric HER2 testing algorithms in the mCRC setting. Methods: The MOUNTAINEER trial enrolled pts w/ HER2+ mCRC identified using ≥1 method: tissue-based local immunohistochemistry (IHC), in situ hybridization (ISH), and/or next-generation sequencing (NGS) testing. Archival or fresh tumor tissue was submitted to a sponsor-designated central laboratory for confirmatory HER2 testing w/ IHC/FISH per the package insert of the FDA approved assay and scored by both the breast and gastric algorithms for HER2 IHC. A positive result per the breast scoring criteria for IHC requires circumferential membrane staining for HER2, while the gastric criteria allows for circumferential, basolateral, or lateral staining patterns. Results: A total of 114 pts were enrolled with HER2+ tumors per ≥1 local testing methods; 69 pts were HER2+ by NGS, 46 by IHC 3+, and 36 by ISH. Of 105 pts who had tissue available for central HER2 testing w/IHC/FISH, 98 had valid HER2 results; 82/98 (83.7%) of pts had tumors centrally confirmed as HER2+ using both the breast and gastric algorithms. Tissue samples from pts in the MOUNTAINEER trial had 100% concordance between breast and gastric algorithms in HER2 status and 99% concordance in HER2 IHC score. Conclusions: Central pathology testing using both the breast and gastric criteria showed high concordance between these two commonly used algorithms. A high central confirmation rate of local HER2+ results was also observed. These data support the use of either the breast or gastric algorithms to identify HER2+ mCRC tumors until an FDA-approved HER2 assay is available for mCRC. Clinical trial information: NCT03043313 . [Table: see text]

Adjuvant chemotherapy for resected intrahepatic cholangiocarcinoma confers no survival advantage

560

Background: Randomized data suggest improved survival with adjuvant chemotherapy for biliary tract cancers, but subset analyses of intrahepatic cholangiocarcinoma (ICC) show limited survival benefit. This study uses a large bi-institutional cohort of resected ICC patients to evaluate the impact of adjuvant therapy on recurrence patterns and overall survival (OS) and compares these findings to data from a national cancer registry. Methods: Patients with resected ICC were identified within a bi-institutional cohort (Duke and Memorial Sloan Kettering, 1997-2020) and the National Cancer Database (NCDB, 2010-2018). Patients were stratified by treatment with adjuvant chemotherapy (adj). Site of first recurrence was categorized as local (liver only), regional (liver and perihepatic nodes), nodal (perihepatic nodes only), distant, or mixed (both liver and distant). OS was compared with Kaplan-Meier methods. Results: 367 patients underwent resection for ICC, and 163 (44%) patients received adjuvant therapy. Median follow-up was 33 vs. 44 months (adj vs observation (obs), p=0.15). 263 (72%) patients had recurrent disease, most commonly in the liver (72%). There was no difference in recurrence patterns stratified by treatment with adjuvant chemotherapy (% recurrence, adj vs obs; local: 42 vs 42; regional: 2 vs 2; nodal: 0 vs 3; distant only: 27 vs 26; mixed: 29 vs 27, p=0.5). OS was the same between groups (adj vs obs; 42 vs 49 months, p=0.3) and when stratified by recurrence site (p=0.5). Similarly, in an NCDB cohort of 1,159 ICC patients over the same time period, there was no association between adjuvant therapy and OS (adj vs obs; 49 vs 57 months, p=0.1). Conclusions: In this retrospective dual registry analysis, corroborated by national data, adjuvant chemotherapy was not associated with an improvement in OS in ICC patients subjected to curative intent resection. Further, adjuvant therapy had no impact on the high rate of hepatic recurrence, suggesting that alternative strategies, such as liver directed therapies, are needed to improve recurrence rates and OS.

MOUNTAINEER-03: Phase 3 study of tucatinib, trastuzumab, and mFOLFOX6 as first-line treatment in HER2+ metastatic colorectal cancer—Trial in progress

TPS261

Background: Current standard of care (SOC) for treatment (tx) of metastatic colorectal cancer (mCRC) is multi-agent chemotherapy, w/ or w/o a VEGF- or EGFR-inhibitor. HER2 is a validated clinical target in breast and gastric cancers. HER2 amplification occurs in 3%-5% of patients (pts) w/ mCRC; the rate of HER2 amplification can increase to ~10% in pts w/ RAS/BRAF wild-type mCRC tumors. Tucatinib (TUC), a highly selective, HER2-directed tyrosine kinase inhibitor, is approved in multiple regions for HER2+ metastatic breast cancer and is being investigated in gastrointestinal cancers. MOUNTAINEER (NCT03043313) evaluated the safety and efficacy of TUC and trastuzumab (Tras) in pts w/ tx refractory RAS wild-type, HER2+ mCRC. Results from the primary endpoint analysis showed clinically meaningful activity (confirmed ORR of 38.1% and median DOR of 12.4 months) and demonstrated TUC + Tras was well tolerated with a low discontinuation rate (5.8%) and no deaths due to AEs. MOUNTAINEER-03 will further investigate TUC in combo w/ mFOLFOX and Tras in pts w/ RAS wild-type, HER2+ mCRC. Methods: MOUNTAINEER-03 (NCT05253651) is a global, open label, randomized, phase 3 study for 1L tx of HER2+ and RAS wild-type mCRC. Approximately 400 pts will be randomized 1:1 to the TUC experimental arm (TUC [300 mg PO BID] + Tras + mFOLFOX) or the SOC arm (mFOLFOX alone or in combo w/ either bevacizumab or cetuximab). HER2 status is determined centrally w/ tissue based HER2 immunohistochemistry and in situ hybridization assays. Eligible pts must not have received prior tx in the metastatic setting but may have received adjuvant tx if completed > 6 months prior to enrollment. Pts must be ≥18 years of age w/ an ECOG performance status of ≤1 and RAS wild-type mCRC. Pts w/ treated stable central nervous system metastases are eligible. Randomization is stratified by primary tumor location (left-sided vs other) and liver metastases (presence/absence). Primary endpoint is progression-free survival per RECIST v1.1, assessed by blinded independent central review (BICR). Key secondary endpoints are overall survival and confirmed objective response rate per RECIST v1.1 assessed by BICR. Enrollment is ongoing in the US, w/ global sites planned. Clinical trial information: NCT05253651 .

Circulating tumor DNA (ctDNA) for response assessment in patients with anal cancer treated with definitive chemoradiation

1

Background: We hypothesized that circulating tumor DNA (ctDNA) clearance could provide an early signal for clinical complete response (cCR) and/ or long-term recurrence compared to standard clinical exam modalities in patients with anal squamous cell carcinoma (ASCC) undergoing definitive chemoradiation (CRT). Methods: Since early 2021 patients with ASCC undergoing CRT at 2 institutions were offered ctDNA monitoring with a commercially available tumor-bespoke multiplex PCR assay. All patients provided written informed consent for ctDNA testing. Patients were clinically restaged, 3-4 months post-CRT, by clinical exam, endoscopy, and/ or MRI and annually with CT chest, abdomen, and pelvis. cCR was defined as no tumor by digital exam, endoscopy and/or MRI. Molecular ctDNA response is described according to cCR, tumor recurrence, and survival. Results: From January 2021 to September 2022, 31 patients with ASCC treated with definitive CRT underwent ctDNA response assessment. The majority (68%) of patients had stage III disease. Patients were treated to a median radiation dose of 54Gy in 27 fractions with combinatorial mitomycin and fluoropyrimidine-based chemotherapy in 94%, and fluoropyrimidine-based chemotherapy alone in 6%. The median follow up was 22 weeks. ctDNA testing was performed in 25 of these patients at baseline, 26 patients during CRT, and 20 patients 30-days post-CRT. At baseline 88% of patients had detectable ctDNA. Patients with stage III, as compared to stage I-II, disease had numerically higher baseline ctDNA levels (26 vs 4 mean tumor molecules per milliliter (MTM/mL), p=0.08). ctDNA levels decreased with treatment (19 vs 0.9 MTM/mL, p=0.05) among the 18 patients with detectable ctDNA and ctDNA tested during CRT, with 50% of patients entering molecular remission. Similarly, ctDNA levels decreased (21 vs 0.2 MTM/mL, p=0.05) among the 16 patients with detectable ctDNA and ctDNA tested post-CRT, with 94% entering molecular remission. All patients in molecular remission were confirmed to have a cCR. Time to molecular ctDNA remission was significantly shorter than time to cCR (median 30 vs 135 days, p <0.01). There were no molecular recurrences among the 16, 14, and 7 patients with ctDNA testing at 2-4 months, 4-8 months, and 8-12 months post-CRT. All patients are alive and without clinical/ radiographic evidence of disease. Conclusions: Surveillance ctDNA monitoring may provide an earlier response assessment for patients with ASCC undergoing CRT compared to standard clinical measures. Longer term follow-up is required to determine if ctDNA response correlates with long term recurrence free survival. Larger trials are needed to assess the clinical utility of integrating molecular ctDNA response in therapeutic response surveillance.

Genomic landscape of acquired resistance to targeted therapies in metastatic colorectal cancer (mCRC)

190

Background: Therapies targeting oncogenic driver mutations have radically altered the treatment paradigm for mCRC and improved outcomes. New selective inhibitors aim to expand the portion of mCRC with targetable alterations. However, these drugs are limited by a relatively short duration of response before the emergence of acquired resistance. We hypothesized that both the putative resistance mechanism (mutations (MUT) versus copy number alterations (CNA)) and the clonality of the emergent mutations may influence time to resistance. Methods: We screened the MSKCC IMPACT dataset of 5,403 MSS (microsatellite stable) CRC patient samples (3,704 primary sequenced, 1669 metastatic site sequenced) for patients (pts) who had been treated with targeted therapies against EGFR, BRAF, KRAS G12C, or HER2 with tissue or liquid biopsy samples profiled at progression. Clinicopathological features and acquired genomic changes emerging at resistance were assessed. Results: 42 pts were identified with targeted oncogenic drivers consisting of BRAF V600E (17 pts), EGFR (12 pts), KRAS G12C (11 pts), and HER2 (2 pts). Progression specimens analyzed consisted of tissue biopsies in 17 pts (40%) and circulating free DNA (cfDNA) in 21 pts (50%), 4 pts had both tissue and cfDNA analyzed at progression. Median time on targeted therapy (TOT) was 7.1 months (95% CI: 5.6-8.5). Putative resistance alterations were identified in 33 pts (79%) (18 cfDNA, 11 tissue, 4 both cfDNA and tissue) and consisted of MUT alone in 30%, MUT+CNA or rearrangement 70%. Concurrent PIK3CA mutations in pre-treatment tissues were identified in 17 pts (40%) and did not associate with TOT (p=0.68); acquired PI3K pathway alterations were identified in 5 pts (12%), including 2 pts who had baseline tumor PIK3CA mutation. Number of putative resistance alterations ranged from 0-13, with multiple resistance alterations identified in 18 pts (15 ctDNA, 3 tissue), and these could be categorized into three groups: one alteration (15/33; 45%), 2-4 alterations (8/33; 24%), and ≥5 alterations (10/33; 30%). Evaluating TOT by type of alteration: MUT only: 9.8 months, MUT+ CNA+/- rearrangement: 6.6 months (p=0.0079). Evaluating TOT by number of alterations: >4 alterations: 6.1 months versus 1-4 alterations: 8.9 months (p=0.012), or 1 alteration: 8.0 months versus >1 alteration: 6.7months (p= 0.5). There was no significant difference in TOT when evaluating by clonality of mutations, where subclonal was defined as <5% of highest variant allelic fraction (clonal vs subclonal, 9.7 vs 6.7 months, p= 0.09). Fusions identified at time of resistance (involving BRAF in 2 pts, MET in 1 pt, RET in 1 pt) occurred with ≥5 alterations in 3 of 4 pts. Conclusions: Presence of CNA and ≥5 new alterations at resistance were associated with shorter TOT, and there was a trend for subclonal alterations and shorter TOT. New approaches that target underlying mechanisms for these changes may extend TOT.

Organ preservation and total neoadjuvant therapy for rectal cancer: Investigating long-course chemoradiation versus short-course radiation therapy

10

Background: Interest in organ preservation (OP) strategies for rectal cancer (RC) patients persists. The efficacy of long course chemoradiation (LCRT) vs. short course radiation therapy (SCRT) relative to OP is unknown. We compared OP rates between SCRT and LCRT total neoadjuvant therapy (TNT) strategies. Methods: During the COVID-19 pandemic we established an institutional SCRT mandate with no exceptions. For comparison, we identified RC patients treated with LCRT immediately before and after the mandate period. After completion of TNT, patients were restaged by clinical exam, endoscopy, and MRI. A watch and wait (WW) approach was recommended for patients with a clinical complete response (cCR), defined by the MSK regression schema. Total mesorectal excision (TME) was recommended for non-cCR patients. OP was defined as alive, TME-free, and with no evidence of disease in the pelvis. We performed survival analysis for: local regrowth rate, OP, disease-free survival (DFS), and overall survival (OS). Results: We identified 563 consecutive patients with RC treated with TNT, of whom 231 were excluded due to either metastatic disease, synchronous/metachronous malignancies, or non-adenocarcinoma histology (Jan. 2018-Jan. 2021). Patient and tumor characteristics were similar in the LCRT (n = 256) and SCRT (n = 76) cohorts. No significant differences in high-risk features were noted. Most patients had clinical stage III disease (82% in LCRT vs. 83% in SCRT). Induction chemotherapy followed by consolidative radiation was the most common treatment order (78% (LCRT) vs. 70% (SCRT)). The median interval from end of TNT to clinical restaging was 8 weeks (LCRT) and 9 weeks (SCRT). The cCR rate was 46% in both cohorts. The cCR rate was numerically higher in patients treated with radiation first, as compared to chemotherapy first (53% vs. 44% (LCRT) and 52% vs. 43% (SCRT)). Among patients with a cCR, the likelihood of WW management was similar (98% (LCRT) vs. 94% (SCRT)). From start of TNT, the median follow-up was 32 and 28 months respectively for LCRT and SCRT. The 2-year OS (95% vs. 92%), DFS (78% vs 70%), and distant recurrence (20% vs. 21%) rates were similar. Among all patients, the 2-year OP rate was 40% (95% CI 35-47%) for LCRT and 29% (95% CI 20-42%) with SCRT. In those patients managed by WW, the 2-year local regrowth rate was 20% (95% CI 12-27%) with LCRT vs. 36% (95% CI 16-52%) with SCRT. Conclusions: In this nonrandomized comparison, while cCR rates were similar, we observed a numerically higher OP rate with LCRT-TNT than with SCRT-TNT. The ongoing ACO/ARO/AIO-18.1 trial, hypothesizing that LCRT-TNT will increase OP rates relative to SCRT-TNT, should definitively answer this question.

Genetic heterogeneity of intrahepatic cholangiocarcinoma: Implications for outcome

595

Background: Intrahepatic cholangiocarcinoma (IHC) is characterized by marked clinical heterogeneity, likely the result of multiple cells of origin and variable driver gene alterations. The hidden-genome classifier is a statistical algorithm that classifies tumors by integrating multi-level genomic features. In this study, we trained the hidden-genome classifier with extrahepatic cholangiocarcinoma (EHC), gallbladder cancer (GBC) and hepatocellular carcinoma (HCC) as extremes of a spectrum to quantify the genetic heterogeneity of IHC with a view toward improved tumor classification. Methods: An IRB approved retrospective review of patients with biopsy confirmed IHC, EHC, GBC and HCC was conducted. All tumors were subjected to MSK-IMPACT to determine the mutational profile. A two-class model was built and internally validated with the genomic data of EHC/GBC as one class and HCC as the other class. IHC tumors were analyzed in the model and classified into three groups based on their proportional genetic resemblance to EHC/GBC (Biliary Class) or HCC (HCC Class), with the remainder as Intermediate Class. The classification thresholds were 90% resemblance to EHC/GBC or HCC and were determined by the inflection point of predicted survival. The survivals of the three groups were analyzed and compared. Results: A total of 1497 patients were included: IHC (733), EHC (208), GBC (258) and HCC (298). 527 IHC tumors with complete metagenetic information were analyzed in the model, showing a continuous spectrum of alterations, ranging from Biliary Class (122 tumors), Intermediate Class (375 tumors) to HCC Class (30 tumor). The biliary-class IHC was characterized by frequent alterations of IDH1 R132C, KRAS, SMAD4, ERBB2 gain, MDM2 gain, and CKDN2A loss, while the HCC-class IHC was primarily characterized by TERT alterations. In patients with unresected IHCs, the median survival ranged from 1 year (CI 0.77, 1.5) in Biliary Class, 1.8 years (CI 1.5, 2.0) in Intermediate Class, to 2 years (CI 0.93, NR) in HCC Class. In patients subjected to resection, the median survival of Biliary Class (2.4 years, CI 2.1, NR) was lower than both the Intermediate Class (5.1 years, CI 4.8, 6.9) and the HCC Class (3.4 years, CI 2.7, NR). Conclusions: By integrating multi-level genomic features, we leveraged the mutational heterogeneity to classify IHC based on its resemblance to EHC/GBC or HCC tumors. We found that the survival in IHC patients appeared to decline with increasing genomic similarity to Biliary Class. The results support a genomic basis for IHC’s variable clinical behavior and point to a role of mutational testing to guide clinical intervention. [Table: see text]

Clinical Importance of Clonal Hematopoiesis in Metastatic Gastrointestinal Tract Cancers

Importance

Clonal hematopoiesis (CH) has been associated with development of atherosclerosis and leukemia and worse survival among patients with cancer; however, the association with cancer therapy efficacy, in particular immune checkpoint blockade (ICB), and toxicity has not yet been established. Given the widespread use of ICB and the critical role hematopoietic stem cell-derived lymphocytes play in mediating antitumor responses, CH may be associated with therapeutic efficacy and hematologic toxicity.

Objective

To determine the association between CH and outcomes, hematologic toxicity, and therapeutic efficacy in patients with metastatic gastrointestinal tract cancers being treated with systemic therapy, both in the first-line metastatic treatment setting and in ICB.

Design, Setting, and Participants

This retrospective cohort study included 633 patients with stage IV colorectal (CRC) and esophagogastric (EGC) cancer who were treated with first-line chemotherapy and/or ICB at Memorial Sloan Kettering Cancer Center. Patients underwent matched tumor and peripheral blood DNA sequencing using the Memorial Sloan Kettering-Integrated Mutation Profiling of Actionable Cancer Targets next-generation sequencing assay between January 1, 2006, and December 31, 2020.

Exposures

Clonal hematopoiesis-related genetic alterations were identified by next-generation sequencing of patients' tumor and normal blood buffy coat samples, with a subset of these CH alterations annotated as likely putative drivers (CH-PD) based upon previously established criteria.

Main Outcomes and Measures

Patients with CH and CH-PD in peripheral blood samples were identified, and these findings were correlated with survival outcomes (progression-free survival [PFS] and overall survival [OS]) during first-line chemotherapy and ICB, as well as baseline white blood cell levels and the need for granulocyte colony-stimulating factor (G-CSF) support.

Results

Among the 633 patients included in the study (390 men [61.6%]; median age, 58 [IQR, 48-66] years), the median age was 52 (IQR, 45-63) years in the CRC group and 61 (IQR, 53-69) years in the EGC group. In the CRC group, 161 of 301 patients (53.5%) were men, compared with 229 of 332 patients (69.0%) in the EGC group. Overall, 62 patients (9.8%) were Asian, 45 (7.1%) were Black or African American, 482 (76.1%) were White, and 44 (7.0%) were of unknown race or ethnicity. Presence of CH was identified in 115 patients with EGC (34.6%) and 83 with CRC (27.6%), with approximately half of these patients harboring CH-PD (CRC group, 44 of 83 [53.0%]; EGC group, 55 of 115 [47.8%]). Patients with EGC and CH-PD exhibited a significantly worse median OS of 16.0 (95% CI, 11.6-22.3) months compared with 21.6 (95% CI, 19.6-24.3) months for those without CH-PD (P = .01). For patients with CRC and EGC, CH and CH-PD were not associated with PFS differences in patients undergoing ICB or first-line chemotherapy. Neither CH nor CH-PD were correlated with baseline leukocyte levels or increased need for G-CSF support.

Conclusions and Relevance

These findings suggest CH and CH-PD are not directly associated with the treatment course of patients with metastatic gastrointestinal tract cancer receiving cancer-directed therapy.

Colorectal cohort analysis from the Intraperitoneal Chemotherapy After Cytoreductive Surgery for Peritoneal Metastasis (ICARuS) clinical trial

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Background: ICARuS is a randomized phase II, multicenter trial to evaluate the relative efficacy of Hyperthermic Intraperitoneal Chemotherapy (HIPEC) with mitomycin C vs. Early Postoperative Intraperitoneal Chemotherapy (EPIC) with floxuridine (FUDR), after cytoreductive surgery (CRS), for the treatment of peritoneal metastases (PM) from colorectal (CRC) or appendiceal cancer (AC). PRODIGE7 results failed to demonstrate benefit of HIPEC therapy after complete gross resection of CRC PM, prompting termination of CRC accrual and early cohort analysis. Methods: Patients with isolated, confirmed PM were eligible for 1:1 randomization to CRS plus HIPEC with mitomycin C or CRS plus EPIC with FUDR. Patients were stratified by recent systemic chemotherapy and disease (AC vs. CRC). The trial was originally powered to evaluate 212 patients for a 20% gain in a primary endpoint of 3-year progression free survival (PFS: HR = 1.75). Results: Seventy-five CRC patients were included between 4/2013 and 12/2018 for HIPEC (N = 40) or EPIC (N = 35) treatment. Baseline characteristics were well balanced. After a median follow up of 36 months, the median PFS was 7.7 months (95% CI: 6.3-11.1) in the HIPEC arm and 8.8 months (95% CI: 7.1-21.9) in the EPIC arm, HR = 0.69 (95% CI: 0.42-1.14) p = 0.14. In the 42 left-sided primary cancers, the median PFS was 8.4 months (95% CI: 6.4-17.7) in the HIPEC arm and 12.5 months (95% CI: 8.1-NR) in the EPIC arm, HR = 0.60 (95% CI: 0.29-1.22) p = 0.14. In the 33 right-sided primary cancers, the median PFS was 6.5 months (95% CI: 5.5-14.1) in the HIPEC arm and 8 months (95% CI: 5.8-24.1) in the EPIC arm, HR = 0.80 (95% CI: 0.39-1.64) p = 0.53. PFS was significantly better in the EPIC arm among patients with BRAF wildtype (WT) tumors and patients with higher PM burden (PCI > 7). There was no difference between HIPEC and EPIC in the primary toxicity endpoint of complications grade 3 or above (23 vs. 34%, p = 0.3). Conclusions: Three-year PFS did not significantly differ between treatment arms. The lack of survival benefit of HIPEC in the entire cohort and in subset analysis is consistent with the findings of PRODIGE7. ICARuS remains open to accrual for AC. These data support further investigation of the potential benefit of EPIC with CRS in carefully selected patients with CRC PM. Clinical trial information: NCT01815359 .

Radiation exposure from diagnostic CT for young patients with colon cancer in the first 5 years after diagnosis

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Background: Given the rise in colorectal cancer (CRC) in younger patients, this study aims to analyze the radiation exposure received by early onset colorectal cancer patients from diagnostic imaging performed in the first 5-years from diagnosis. Methods: A retrospective review of all patients (age ≤ 50 y) with stage I-III CRC who received at least 5 surveillance or staging body computed tomography (CT) scans in the 5 years from diagnosis was performed beginning in October 2015. The volume CT dose index (CTDIvol) and dose length product (DLP) were extracted; a previously validated Monte Carlo (MC) based software, VirtualDose (Virtual Phantoms, Inc., Albany, NY), was used to estimate organ dose to 19 organs based on the imaging mode parameters. The effective doses were calculated based on methods set forth in the International Commission on Radiological Protection ICRP No. 103 Publication. Results: A total of 107 patients were included (age range 25-50 years, median 44 years). The average effective dose per CT scan was 15.0 mSv range: 11.6 to 22.6 mSv) for male (n = 62) and 13.4 mSv (8.04 to 17.5 mSv) for female (n = 45) patients. The cumulative effective dose was greater than 100 mSv for 9 (8.4%) of patients and between 50 to < 100 mSv for 28 (26.2%) of the patients in this study. Of the 107 patients, 23% (n = 25) of the patients recurred during the first 5 years. Conclusions: The majority of early-onset colorectal cancer patients in this study received a cumulative dose under 100 mSv, which is considered low risk according to a policy statement by the International Organization for Medical Physics. Since the majority of patients in this study received what is considered a low cumulative radiation dose from repeated CT imaging during the 5-year period after diagnosis, this may provide reassurance that repeated CT imaging, particularly for surveillance, is warranted. Individual risk will vary but the clinical benefits of clinical imaging outweigh the small, if any, risk of radiation-induced cancers in this patient cohort. [Table: see text]

Concordance in oncogenic alterations between primary and recurrent/metastatic cholangiocarcinoma pairs using targeted next-generation sequencing

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Background: The genetic background of cholangiocarcinoma (CCA) commonly involves alterations in kinase signaling, tumor suppression, oxidative stress modulation, and proto-oncogenic coupling pathways. Novel agents targeting such pathways have shown promise in systemic treatment; however, studies examining differences in the mutational landscapes between primary and recurrent, metastatic, or progressive disease after systemic therapy are lacking. The present study aimed to determine if recurrent, metastatic, or progressive disease genetically parallels the primary or not. Methods: Patients with biopsy proven CCA (primary tumor and paired recurrent/metastatic or progressive disease) from two institutions (MSKCC and Duke) were identified. Targeted next-generation sequencing (Integrated Mutation Profiling of Actionable Cancer Targets (IMPACT)) capturing single nucleotide variants, copy number alterations, and structural variants was used to compare driver alteration concordance across the paired samples. Subgroup analyses were performed based on exposure to systemic therapy in patients with disease progression and tumor type (intrahepatic versus extrahepatic). Results: Sample pairs from 65 patients with intrahepatic (ICCA, n=54) and extrahepatic CCA (ECCA, n=11) were analyzed. Median time between samples was 19.6 months (range 2.7 - 122.9). Some de novo alterations were identified in recurrent/metastatic samples, but overall concordance (70%) was demonstrated between patient pairs for common oncogenic driver genes (Table). Subgroup analyses of summative ICCA and ECCA mutations revealed concordance of 65% and 88%, respectively. Concordance was also demonstrated between pairs exposed to systemic therapy between sample collections (n=50, 71%). Conclusions: In this dataset of CCA patients, a concordance rate of 70% was identified in the genomic alterations between primary and recurrent/metastatic pairs, and this did not appear to be altered by prior treatment with systemic chemotherapy. While limited by sample size, concordance in ICCA pairs was lower than that seen in ECCA. [Table: see text]

Treatment of Metastatic Colorectal Cancer: ASCO Guideline

PURPOSE

To develop recommendations for treatment of patients with metastatic colorectal cancer (mCRC).

METHODS

ASCO convened an Expert Panel to conduct a systematic review of relevant studies and develop recommendations for clinical practice.

RESULTS

Five systematic reviews and 10 randomized controlled trials met the systematic review inclusion criteria.

RECOMMENDATIONS

Doublet chemotherapy should be offered, or triplet therapy may be offered to patients with previously untreated, initially unresectable mCRC, on the basis of included studies of chemotherapy in combination with anti-vascular endothelial growth factor antibodies. In the first-line setting, pembrolizumab is recommended for patients with mCRC and microsatellite instability-high or deficient mismatch repair tumors; chemotherapy and anti-epidermal growth factor receptor therapy is recommended for microsatellite stable or proficient mismatch repair left-sided treatment-naive RAS wild-type mCRC; chemotherapy and anti-vascular endothelial growth factor therapy is recommended for microsatellite stable or proficient mismatch repair RAS wild-type right-sided mCRC. Encorafenib plus cetuximab is recommended for patients with previously treated BRAF V600E-mutant mCRC that has progressed after at least one previous line of therapy. Cytoreductive surgery plus systemic chemotherapy may be recommended for selected patients with colorectal peritoneal metastases; however, the addition of hyperthermic intraperitoneal chemotherapy is not recommended. Stereotactic body radiation therapy may be recommended following systemic therapy for patients with oligometastases of the liver who are not considered candidates for resection. Selective internal radiation therapy is not routinely recommended for patients with unilobar or bilobar metastases of the liver. Perioperative chemotherapy or surgery alone should be offered to patients with mCRC who are candidates for potentially curative resection of liver metastases. Multidisciplinary team management and shared decision making are recommended. Qualifying statements with further details related to implementation of guideline recommendations are also included.Additional information is available at www.asco.org/gastrointestinal-cancer-guidelines.

Local Therapy for Oligoprogression or Consolidation in High Mutational Burden Stage 4 Colorectal Cancer Treated With PD-1 or PD-L1 Blockade

BACKGROUND

Immune checkpoint blockade (ICI) of programmed cell death protein 1 (PD-1) or PD-1 ligand (PD-L1) can induce durable responses in patients who have colorectal cancer (CRC) with a high tumor mutational burden (TMB). Two recurring clinical dilemmas show how to manage oligoprogressive disease and stable disease after ICI.

METHODS

A cohort study was conducted to analyze patients with metastatic CRC who underwent PD-1 or PD-L1 blockade. Tumors were mismatch repair (MMR) deficient or had more than 25 mutations per megabase. Patients were identified who had local therapy (surgery, ablation, or radiotherapy) for one to three sites of progressive disease (PD) or surgery to consolidate SD. The study evaluated clinical and biologic factors associated with patient selection, outcomes, and pathologic response rates.

RESULTS

From 2014 to 2020, treatment was administered to 111 patients with ICI. Of these 111 patients, 19 (17%) survived fewer than 6 months, whereas to date, 50 have not had progression of disease. The remaining 42 patients experienced PD, and 16 (38%) were treated with local therapy for oligoprogression. Selection for local therapy was associated with response to ICI. The 2-year progression-free survival (PFS) after local therapy was 62%. Finally, 6 of the 50 patients without PD had consolidation of SD, and 5 had complete or near complete pathologic responses.

CONCLUSIONS

Oligoprogression, a frequent pattern of failure after ICI, can be managed effectively with local therapy. In contrast, it may not be necessary to consolidate SD for selected patients. Further research is essential to define management algorithms better and to explore heterogeneity in response patterns.

Considerations and barriers to starting a new HAI pump program: an international survey of the HAI Consortium Research Network

BACKGROUND

Widespread implementation of HAI pump chemotherapy has been limited by logistic and feasibility concerns. Recent studies demonstrating excellent outcomes have fueled renewed enthusiasm and multiple new programs have emerged. This survey aims to identify barriers critical to establish a successful HAI program.

METHODS

Using SurveyMonkey™, a 17-question survey assessing factors required for establishing a successful program was developed by 12 HAI Consortium Research Network (HCRN) surgical oncologists. Content analysis was used to code textual responses. Frequency of categories and average rank scores for each choice were calculated.

RESULTS

Twenty-eight HCRN members responded to the survey. Implementation time varied, with 15 institutions requiring less than a year. Most programs (n = 17) became active in the past 5 years. Medical and surgical oncology were ranked most important for building a program (average ranking scores: 7.96 and 6.59/8). Administrative or regulatory approval was required at half of the institutions. The top 3 challenges faced when building a program were related to regulatory approval (6.65/9), device/equipment access (6.33/9), and drug (FUDR) access (6.25/9).

CONCLUSION

Development of successful programs outside of historically established centers is feasible and requires a multidisciplinary team. Future collaborative efforts are critical for sustainability of safe/effective new programs.

Clinical features of young onset colorectal cancer patients from a large cohort at a single cancer center

PURPOSE

The aim of this study is to describe the demographics and clinical features of patients with young onset (YO) CRC.

METHODS

A retrospective review of patients with CRC diagnosed between ages 20 and 49 years was evaluated at the Memorial Sloan Kettering Cancer Center from 1/2004 to 6/2019. We excluded those with a hereditary CRC syndrome, inflammatory bowel disease, or prior CRC diagnosis. Patient demographics; presenting symptoms; medical, surgical, and smoking history; family history of cancer; tumor characteristics; and pathology were obtained from the electronic medical record.

RESULTS

We identified 3856 YO CRC patients (median age CRC diagnosis 43; 52.5% male). A total of 59.1% were overweight or obese (32.2% and 26.9%, respectively). Most (90.1%) had no family history of CRC in a first-degree relative; 56.3% of patients reported being never smokers; 5.2% had diabetes. The most common presenting symptoms were rectal bleeding (47.7%), abdominal pain/bloating (33.1%), and change in bowel habits (24.7%). The majority presented with left-sided cancers (77.3%), at late-stage disease (68.4% at stages 3 or 4).

CONCLUSION

Most YO CRC patients presented with rectal bleeding or abdominal pain, left-sided cancers, and later-stage disease and had no family history of CRC in a first-degree relative. Over half were overweight and obese and were more likely to have never smoked. More data are needed to better understand YO CRC risk factors and to help identify high-risk populations who may benefit from earlier screening.

A Dynamic Clinical Calculator for Estimating Conditional Recurrence-Free Survival After Total Neoadjuvant Therapy for Rectal Cancer and Either Surgery or Watch-and-Wait Management

IMPORTANCE

The risk of recurrence in patients with locally advanced rectal cancer has historically been determined after surgery, relying on pathologic variables. A growing number of patients are being treated without surgery, and their risk of recurrence needs to be calculated differently.

OBJECTIVE

To develop a dynamic calculator for estimating the probability of recurrence-free survival (RFS) in patients with rectal cancer who undergo total neoadjuvant therapy (TNT) (induction systemic chemotherapy and chemoradiotherapy) and either surgery or watch-and-wait management.

DESIGN, SETTING, AND PARTICIPANTS

This cohort study included patients who presented with stage II or III rectal cancer between June 1, 2009, and March 1, 2015, at a comprehensive cancer center. Conditional modeling was incorporated into a previously validated clinical calculator to allow the probability of RFS to be updated based on whether the patient remained in watch-and-wait management or underwent delayed surgery. Data were analyzed from November 2021 to March 2022.

EXPOSURE

TNT followed by immediate surgery or watch-and-wait management with the possibility of delayed surgery.

MAIN OUTCOMES AND MEASURES

RFS, concordance index, calibration curves.

RESULTS

Of the 302 patients in the cohort, 204 (68%) underwent surgery within 3 months from TNT completion (median [range] age, 51 [22-82] years; 78 [38%] women), 54 (18%) underwent surgery more than 3 months from TNT completion (ie, delayed surgery; median [range] age, 62 [31-87] years; 30 [56%] female), and 44 (14%) remained in watch-and-wait management as of April 21, 2021 (median [range] age, 58 [32-89] years; 16 [36%] women). Among patients who initially opted for watch-and-wait management, migration to surgery due to regrowth or patient choice occurred mostly within the first year following completion of TNT, and RFS did not differ significantly whether surgery was performed 3.0 to 5.9 months (73%; 95% CI, 52%-92%) vs 6.0 to 11.9 months (71%; 95% CI, 51%-99%) vs more than 12.0 months (70%; 95% CI, 49%-100%) from TNT completion (P = .70). RFS for patients in the watch-and-wait cohort at 12 months from completion of TNT more closely resembled patients who had undergone surgery and had a pathologic complete response than the watch-and-wait cohort at 3 months from completion of TNT. Accordingly, model performance improved over time, and the concordance index increased from 0.62 (95% CI, 0.53-0.71) at 3 months after TNT to 0.66 (95% CI, 0-0.75) at 12 months.

CONCLUSIONS AND RELEVANCE

In this cohort study of patients with rectal cancer, the clinical calculator reliably estimated the likelihood of RFS for patients who underwent surgery immediately after TNT, patients who underwent delayed surgery after entering watch-and-wait management, and patients who remained in watch-and-wait management. Delayed surgery following attempted watch-and-wait did not appear to compromise oncologic outcomes. The risk calculator provided conditional survival estimates at any time during surveillance and could help physicians counsel patients with rectal cancer about the consequences of alternative treatment pathways and thereby support informed decisions that incorporate patients' preferences.

Practical Considerations in Diagnosing and Managing Early-Onset GI Cancers

The incidence of early-onset (EO) GI cancers occurring in individuals younger than age 50 years has been rising at an alarming rate over the past two decades. Although this rise in incidence among young patients correlates with increased rates of obesity, changes in diet, and alterations in the environment, the effects of these environmental factors on carcinogenesis, metastasis, and treatment response are unknown. Although several unique clinical trends exist among EO-GI cancers and their average-onset GI cancer counterparts, GI cancers are molecularly indistinct between younger and older patients, and no data support distinct treatment paradigms for patients with EO disease. The majority of EO-GI cancers are not explained by germline changes. There remains a critical need for further research to understand the pathogenesis and optimal management of EO-GI cancers. In addition, current screening strategies are not adequate to identify EO-GI cancers, and early biomarkers are needed. Specialized centers, with a focus on psychosocial aspects of cancer management, can address the unique care needs of patients with EO-GI cancers.

Organ Preservation in Patients With Rectal Adenocarcinoma Treated With Total Neoadjuvant Therapy

PURPOSE

Prospective data on the efficacy of a watch-and-wait strategy to achieve organ preservation in patients with locally advanced rectal cancer treated with total neoadjuvant therapy are limited.

METHODS

In this prospective, randomized phase II trial, we assessed the outcomes of 324 patients with stage II or III rectal adenocarcinoma treated with induction chemotherapy followed by chemoradiotherapy (INCT-CRT) or chemoradiotherapy followed by consolidation chemotherapy (CRT-CNCT) and either total mesorectal excision (TME) or watch-and-wait on the basis of tumor response. Patients in both groups received 4 months of infusional fluorouracil-leucovorin-oxaliplatin or capecitabine-oxaliplatin and 5,000 to 5,600 cGy of radiation combined with either continuous infusion fluorouracil or capecitabine during radiotherapy. The trial was designed as two stand-alone studies with disease-free survival (DFS) as the primary end point for both groups, with a comparison to a null hypothesis on the basis of historical data. The secondary end point was TME-free survival.

RESULTS

Median follow-up was 3 years. Three-year DFS was 76% (95% CI, 69 to 84) for the INCT-CRT group and 76% (95% CI, 69 to 83) for the CRT-CNCT group, in line with the 3-year DFS rate (75%) observed historically. Three-year TME-free survival was 41% (95% CI, 33 to 50) in the INCT-CRT group and 53% (95% CI, 45 to 62) in the CRT-CNCT group. No differences were found between groups in local recurrence-free survival, distant metastasis-free survival, or overall survival. Patients who underwent TME after restaging and patients who underwent TME after regrowth had similar DFS rates.

CONCLUSION

Organ preservation is achievable in half of the patients with rectal cancer treated with total neoadjuvant therapy, without an apparent detriment in survival, compared with historical controls treated with chemoradiotherapy, TME, and postoperative chemotherapy.

Organ Preservation in Patients With Rectal Adenocarcinoma Treated With Total Neoadjuvant Therapy

PURPOSE

Prospective data on the efficacy of a watch-and-wait strategy to achieve organ preservation in patients with locally advanced rectal cancer treated with total neoadjuvant therapy are limited.

METHODS

In this prospective, randomized phase II trial, we assessed the outcomes of 324 patients with stage II or III rectal adenocarcinoma treated with induction chemotherapy followed by chemoradiotherapy (INCT-CRT) or chemoradiotherapy followed by consolidation chemotherapy (CRT-CNCT) and either total mesorectal excision (TME) or watch-and-wait on the basis of tumor response. Patients in both groups received 4 months of infusional fluorouracil-leucovorin-oxaliplatin or capecitabine-oxaliplatin and 5,000 to 5,600 cGy of radiation combined with either continuous infusion fluorouracil or capecitabine during radiotherapy. The trial was designed as two stand-alone studies with disease-free survival (DFS) as the primary end point for both groups, with a comparison to a null hypothesis on the basis of historical data. The secondary end point was TME-free survival.

RESULTS

Median follow-up was 3 years. Three-year DFS was 76% (95% CI, 69 to 84) for the INCT-CRT group and 76% (95% CI, 69 to 83) for the CRT-CNCT group, in line with the 3-year DFS rate (75%) observed historically. Three-year TME-free survival was 41% (95% CI, 33 to 50) in the INCT-CRT group and 53% (95% CI, 45 to 62) in the CRT-CNCT group. No differences were found between groups in local recurrence-free survival, distant metastasis-free survival, or overall survival. Patients who underwent TME after restaging and patients who underwent TME after regrowth had similar DFS rates.

CONCLUSION

Organ preservation is achievable in half of the patients with rectal cancer treated with total neoadjuvant therapy, without an apparent detriment in survival, compared with historical controls treated with chemoradiotherapy, TME, and postoperative chemotherapy.