Search Results (147)

Background: Next-generation sequencing (NGS)-detected ERBB2 amplification occurs in a subset of urothelial carcinomas, but its role as a treatment-selection marker for trastuzumab deruxtecan (T-DXd) remains uncertain. Methods: We retrospectively reviewed four patients with metastatic urothelial carcinoma treated with T-DXd in routine practice from 2024. Treatment selection was based on NGS-detected ERBB2 amplification because HER2 immunohistochemistry and in situ hybridization were unavailable. Results: Four men aged 65–76 years received T-DXd: one in the second line and three in the fourth or fifth line. The best radiological responses, abstracted from contemporaneous radiology reports and oncology medical records, were complete response in one patient, partial response in one, and stable disease in two. Three patients had previously received enfortumab vedotin. Documented adverse events included fatigue, anemia, diarrhea, rash, and leukopenia. No interstitial lung disease or pneumonitis was documented in the available records. Conclusions: These observations are descriptive and hypothesis-generating. They do not establish the efficacy or safety of T-DXd or validate ERBB2 amplification as a predictive biomarker, but they support prospective evaluation of genomic ERBB2 amplification when standard HER2 testing is unavailable. Full article

Breast cancer (BC) can be treated by combinations of surgery, radiotherapy, chemotherapy, endocrine therapy and targeted therapies. High-risk patients, including all patients with axillary involved lymph nodes with triple-negative BC (TNBC) and Her2-positive BC, are treated by neoadjuvant chemotherapy (NAC). For high-risk patients, immunotherapy for TNBC, trastuzumab and pertuzumab then trastuzumab deruxtecan for Her2-positive BC have improved survival. In this narrative review, we will discuss therapy for small triple-negative and HER2-positive early BC without involved or suspicious axillary lymph nodes. Upfront surgery is recommended for cT1a-b cN0 usN0 TNBC and Her2-positive BC with adjuvant therapy for pT1b pN0 BC, discussed case by case for pT1a pN0 Her2-positive BC. No adjuvant chemotherapy is considered for pT1a TNBC. However, lymph vascular invasion can also be contributive on pathologic results. For pT1c pN0 TNBC and Her2-positive BC, adjuvant therapy is recommended. For cT2 or cN+ TNBC and Her2-positive BC, NAC is the treatment recommended with adjuvant therapy after surgery according to pathologic results. For cT1c cN0 usN0 TNBC and Her2-positive BC, upfront surgery is the usual treatment proposed but NAC can be strongly considered according to clinic pathologic characteristics, tumor size 10–15 mm or 16–20 mm, grade, young age (≤35-years) and co-morbidities, particularly for elderly patients. Recent tools such as TIL level determined on core needle biopsy may help when considering NAC or upfront surgery and systemic therapy regimens. Other prognostic tools can contribute to the determined therapeutic strategy and systemic therapy regimens with escalation or de-escalation, such as TNBCDX or HER2DX, possibly in combination with TIL level. Full article

Non-small cell lung cancer (NSCLC) comprises a diverse group of malignancies driven by distinct molecular alterations that have become critical targets for precision oncology. Among these, EGFR exon 20 insertion mutations and HER2 dysregulation, including HER2 mutations, amplification, and overexpression, define clinically important subsets of NSCLC characterized by unique biological behavior and historically limited treatment options. Although these alterations account for a relatively small proportion of NSCLC cases, their identification has become increasingly relevant due to advances in molecular diagnostics and the development of novel targeted therapies. This review provides a comprehensive overview of the epidemiology, molecular biology, and clinical characteristics of EGFR exon 20 insertion-mutated and HER2-deregulated NSCLC. We discuss current diagnostic approaches, including the role of next-generation sequencing and biomarker testing, and summarize the evolving therapeutic landscape encompassing conventional chemotherapy, immunotherapy, and targeted agents. Particular attention is given to recently approved therapies and emerging treatment strategies, including tyrosine kinase inhibitors and antibody-based therapies that have demonstrated clinically meaningful activity in these patient populations. We also address the major challenges associated with treatment resistance, molecular heterogeneity, and optimal therapeutic sequencing. Finally, we highlight ongoing research efforts and future perspectives aimed at improving outcomes for patients with these rare but clinically significant molecular subtypes of NSCLC. Full article

Transformative therapeutic innovation should not begin with a molecule—or even a molecular target. It should begin with a clearly defined unmet clinical need. Here, we present a seven-step Translational Therapeutic Development Roadmap that systematically connects an unmet medical need to a developable drug candidate through the disciplined sequence of (i) defining the need, (ii) understanding disease and resistance biology, (iii) building a mechanistic hypothesis, (iv) defining a target product profile (TPP), (v) molecular design and experimental validation, (vi) developability and manufacturability assessment, and (vii) clinical translation. A central conclusion emerging from this review is that resistance biology should be viewed not merely as a cause of therapeutic failure, but as a primary design input for next-generation therapeutic innovation. Our analysis identifies continuous alignment among unmet clinical needs, resistance biology, mechanistic hypothesis, molecular design, developability, and clinical translation as the defining characteristic of successful therapeutic development. We use dual-payload antibody–drug conjugates (ADCs) as a contemporary and highly illustrative case study of this resistance-informed therapeutic development approach. Single-payload ADCs such as trastuzumab deruxtecan and sacituzumab govitecan have transformed treatment across multiple solid tumors, yet most patients ultimately relapse through antigen loss, defective intracellular trafficking, drug efflux, payload-target alterations, and tumor heterogeneity, creating an emerging post-ADC treatment gap. Dual-payload ADCs, which deliver two mechanistically distinct warheads from a single antibody, represent a form of molecular combination therapy designed to increase the barrier to resistance and address multiple escape pathways simultaneously, as well as provide a clinically relevant model for resistance-informed therapeutic design. Using dual-payload ADCs as a worked example, we demonstrate how resistance biology directly informs payload pairing, molecular architecture, conjugation strategy, experimental validation, and developability. Our analysis indicates that successful dual-payload ADC design depends not simply on combining two cytotoxic payloads, but on selecting complementary mechanisms with non-overlapping resistance liabilities while satisfying predefined target product profiles and manufacturability requirements. We further summarize resistance-guided payload pairing strategies, including topoisomerase I plus tubulin inhibitors, topoisomerase I plus DNA-damage-response inhibitors, cytotoxic plus immunomodulatory payloads, and cell-permeable plus non-permeable combinations; the conjugation chemistries that enable defined dual-payload products; the preclinical validation, pharmacological optimization, and developability hurdles that separate promising biology from viable therapeutics; and the rapidly expanding clinical landscape, including the first-in-human program KH815 and emerging bispecific dual-payload constructs. Finally, we demonstrate that the same translational roadmap extends beyond ADCs to radiopharmaceutical conjugates, multispecific antibodies, targeted protein degraders, and cell and gene therapies, indicating that it represents a general framework for therapeutic innovation rather than an ADC-specific strategy. Collectively, this review supports the concept that therapeutic innovation is most successful when unmet clinical needs, resistance biology, molecular design, developability, and clinical translation are considered as an integrated continuum rather than as independent stages of drug discovery. This Translational Therapeutic Development Roadmap provides an organizing framework for guiding the rational development of next-generation targeted therapeutics across diverse therapeutic modalities. Full article

Pancreatic cancer remains one of the most aggressive and lethal malignancies, characterized by late-stage diagnosis, profound molecular heterogeneity, and limited responsiveness to conventional cytotoxic therapies. Recent advances in molecular diagnostics and biomarker-driven treatment stratification have accelerated the development of precision therapeutic approaches aimed at improving outcomes in selected patient populations. This review highlights three mechanistically distinct yet complementary therapeutic strategies that illustrate the evolving landscape of personalized pancreatic cancer management. Adagrasib represents targeted inhibition of oncogenic KRAS G12C signaling, reflecting recent progress in directly targeting historically “undruggable” driver mutations. Dostarlimab illustrates the tissue-agnostic application of immune checkpoint blockade in pancreatic cancers harboring mismatch repair deficiency (dMMR) or high microsatellite instability (MSI-H), highlighting the growing importance of biomarker-defined immunotherapy-responsive subsets despite the limited pancreatic cancer-specific clinical evidence currently available. Trastuzumab deruxtecan represents a next-generation HER2-directed antibody–drug conjugate (ADC) and demonstrates the potential of HER2-targeted therapy in the small subgroup of patients with HER2-positive pancreatic cancer, although the available evidence is derived primarily from basket trials and tumor-agnostic clinical development. Collectively, these therapeutic approaches underscore the expanding role of biomarker-guided treatment strategies integrating targeted inhibition, immunotherapy, and precision cytotoxic payload delivery. This review summarizes the molecular rationale, available clinical evidence, therapeutic limitations, and resistance mechanisms associated with these approaches while discussing emerging directions in translational research, rational combination strategies, liquid biopsy applications, and precision oncology that may further refine individualized treatment algorithms for pancreatic cancer. Full article

Antibody–drug conjugates (ADCs) have received renewed attention in oncology following the clinical and commercial success of agents such as trastuzumab deruxtecan (Enhertu^®), which underscored the clinical importance of coordinated optimization of the antibody, linker, payload, and conjugation strategy. Among these parameters, conjugation strategy strongly influences drug-to-antibody ratio (DAR) distribution, pharmacokinetics, manufacturability, and safety. Over the past two decades, ADC conjugation technologies have evolved from first-generation stochastic modification approaches to second-generation site-specific engineering strategies and, more recently, to third-generation site-selective platforms applicable to native antibodies. First-generation approaches remain the most clinically validated and have the strongest regulatory precedent despite their intrinsic heterogeneity. Second-generation approaches improve positional control and DAR homogeneity, but often increase demands on antibody engineering, expression, and process complexity. Third-generation approaches aim to preserve controlled conjugation while reducing sequence-engineering requirements, yet remain limited by a restricted number of accessible sites and less extensive clinical and regulatory experience. In this review, we summarize the evolution of ADC conjugation technologies, highlight representative clinical and translational examples, and discuss the major trade-offs of each platform. We also propose a practical selection framework based on payload properties, required DAR control, antibody stability, manufacturability, and regulatory considerations, with relevance to next-generation ADCs including dual-payload and bispecific formats. Overall, conjugation strategy should be selected according to the scientific, manufacturing, and regulatory requirements of each ADC program rather than on the basis of a presumed technological hierarchy. Full article

Background: Vulvar cancer is a rare gynecologic malignancy comprising 1–3% of all cases. No established standard exists for advanced disease, and treatment is often extrapolated from cervical cancer. Although HER2 overexpression is well defined in breast cancer and recognized across multiple solid tumors, its prevalence and significance in vulvar cancer remain unclear. Recent activity of HER2-directed antibody–drug conjugate Trastuzumab deruxtecan in solid tumors with an objective response rate (ORR) of around 37% highlights the need to better characterize HER2 expression in vulvar cancer. Methods: We performed a systematic search of Medline, Embase, and the Cochrane Library up to May 2025. Eligible studies included ≥10 vulvar cancer cases, predominantly vulvar squamous cell carcinoma (VSCC), excluding vulvar Paget’s disease, with available HER2 assessment by immunohistochemistry and/or in situ hybridization. Two reviewers independently screened the studies. A random-effects model was used to estimate pooled HER2 positivity. Heterogeneity was assessed using Cochrane’s Q and Higgins’s I². Results: Of 506 records, nine retrospective studies including 769 patients with predominantly squamous cell carcinoma histology (98%, n = 752) met inclusion criteria. A total of 50 HER2-positive cases were observed. Median age at diagnosis of vulvar cancer was between 55 and 78, reported in three studies. Molecular profiling was limited. Among three studies with known TP53 status (n = 206), 59% of the tumors expressed TP53 (n = 122), and among two studies with known human papilloma virus (HPV) status (n = 128), 21% (n = 27) were HPV-positive. Six studies used American Society of Clinical Oncology/College of American Pathologists (ASCO/CAP) HER2 testing guidelines in breast cancer. Pooled HER2-positive expression across ASCO/CAP-based studies was 2% (95% CI: 1%, 3%) and for non-ASCO/CAP-based studies was 21% (95% CI: 2%, 52%). Exploratory pooled estimated proportion of HER2-positive expression was 5% (95% CI: 0.4%, 14%). There was substantial heterogeneity across studies, I² value of 91.1% [95% CI: 85.4%; 94.6%], and no significant publication bias was observed (Egger’s test p = 0.364). This study could not assess prognostic value of HER2 overexpression in VSCC. Conclusions: HER2 positivity in VSCC appears uncommon but it remains to be fully explored. Standardized assessment using contemporary ASCO/CAP breast, endometrial-specific and/or gastric criteria are needed to clarify the prevalence of HER2-positive versus HER2-low/ultralow disease to inform potential use of HER2-targeted therapy. Full article

Background and Objectives: The HER2-low designation has emerged as a clinically actionable category in breast cancer following the approval of trastuzumab deruxtecan for HER2-low metastatic disease. However, the clinical relevance of HER2-low expression in the neoadjuvant chemotherapy (NAC) setting remains uncertain. This study aimed to evaluate pathological complete response (pCR) as the primary endpoint and overall survival (OS) and disease-free survival (DFS) as exploratory secondary endpoints across HER2-low, HER2-zero, and HER2-positive subgroups in a NAC-treated cohort. Materials and Methods: This single-center retrospective cohort study included 118 patients with histopathologically confirmed invasive breast cancer who received NAC at our institution between January 2010 and March 2021. Patients were classified as HER2-zero (IHC 0, n = 66), HER2-low (IHC 1+ or IHC 2+/FISH-non-amplified, n = 17), or HER2-positive (IHC 3+ or IHC 2+/FISH-amplified, n = 35). pCR was defined as ypT0/Tis ypN0. Univariate analyses used χ² or Fisher’s exact tests; multivariable logistic and Cox regression were performed for adjusted analyses, and Kaplan–Meier survival curves were compared by log-rank, Breslow, and Tarone–Ware tests. Results: The overall pCR rate was 24.6%, differing significantly across HER2 subgroups (HER2-positive 45.7%, HER2-low 29.4%, HER2-zero 12.1%; p = 0.001). After multivariable adjustment for age, ER, PR, and tumor grade, HER2-positive status retained an independent association with pCR (OR 4.37, 95% CI 1.46–13.10, p = 0.008), whereas HER2-low status did not (OR 2.65, 95% CI 0.60–11.75, p = 0.201). At a median follow-up of 48.8 months, neither OS (log-rank p = 0.567) nor DFS (log-rank p = 0.901) differed significantly across HER2 subgroups, and HER2 subgroup status was not independently associated with survival in exploratory Cox models. Conclusions: In this NAC-treated cohort, the unadjusted pCR advantage of HER2-low over HER2-zero tumors was not retained after adjustment for hormone receptor expression and tumor grade, and no HER2 subgroup-specific survival difference was demonstrated. Within the standard NAC framework, HER2-low disease did not show a pCR or survival pattern clearly distinct from HER2-zero disease after adjustment; the small HER2-low subgroup and wide confidence intervals preclude firm conclusions, and an exploratory hormone receptor-stratified analysis indicated that the apparent pooled HER2-low advantage was confined to the hormone receptor-negative subgroup. Future prospective studies powered for hormone receptor-stratified analyses are warranted. Full article

Background/Objectives: HER2 overexpression and/or amplification defines a molecularly distinct subset of endometrial carcinomas (ECs) that may benefit from HER2-targeted therapies. However, HER2 testing algorithms remain non-standardized and vary across institutions. This study is a large single-institution audit of EC HER2 testing practices, using both gynecologic (ISGyP) and gastric cancer-specific scoring algorithms at a major academic center with a reference gynecologic oncology service and biomarker laboratory. Methods: HER2 immunohistochemistry (IHC) and whole-slide fluorescence in situ hybridization (FISH) were interpreted by subspecialty breast and gynecologic pathologists, with HER2 IHC performed on 494 tumor samples (2021–2025) and reflex FISH for equivocal cases. Results: Using ISGyP criteria, 15.0% (74/494) of tumors were HER2 IHC 3+, 44.5% (220/494) equivocal (2+), and 40.5% (200/494) were negative (0/1+). Among equivocal cases, 28.2% (58/205) demonstrated ERBB2 amplification, yielding an overall HER2-positive rate of 27.5% (132/480). Re-assessment with gastric scoring criteria demonstrated variability in HER2 classification, with high concordance in cytology specimens (100%) and resections (90.8%; K = 0.842, p < 0.001) but substantially lower concordance in biopsies (60.6%; K = 0.401, p < 0.001), mainly due to reclassification of equivocal cases. Notably, 47.9% (n = 34) of ISGyP-equivocal biopsy specimens were reclassified as HER2 IHC 3+ using gastric biopsy criteria, potentially expanding eligibility for T-DXd therapy. Conclusions: These findings highlight the evolving nature of HER2 testing in EC and demonstrate the significant impact of scoring methodology on HER2 interpretation. Our results support the development of EC-specific HER2 testing guidelines and a dual-reporting approach incorporating both ISGyP and gastric scoring criteria, with selective confirmatory FISH testing, to optimize patient selection for HER2-targeted therapies. Full article

Antibody-drug conjugates (ADCs) have transitioned from clinically marginal agents into a defining therapeutic class for solid tumor oncology. In DESTINY-Breast03, trastuzumab deruxtecan achieved a four-fold progression-free survival advantage over trastuzumab emtansine, attributable not to antibody engineering but to the linker-payload axis: a cleavable peptide linker and a topoisomerase I payload with bystander activity. Sacituzumab govitecan extends the same logic to Trop-2-positive disease via extracellular payload release, and the framework now spans breast, urothelial, gynecologic, lung, gastric, and colorectal cancers, with enfortumab vedotin plus pembrolizumab displacing platinum chemotherapy as first-line therapy for urothelial cancer in EV-302 (median overall survival 31.5 versus 16.1 months). This review synthesizes ADC biology along three analytical axes. The mechanistic axis links each linker-payload-DAR configuration to a specific tumor-biology barrier: vascular limitation, which delivers approximately 0.1% of the administered dose to tumor tissue; the binding-site barrier, which concentrates exposure at the perivascular margin; and antigen mosaicism, which defeats internalization-dependent killing. The translational axis examines resistance as a coordinated failure across antigen modulation, trafficking, efflux, apoptotic execution, and lysosomal processing. The clinical axis traces the platform’s migration toward earlier-line and curative-intent settings. We close by examining whether the ADC delivery architecture translates to precision immunosuppression in autoimmune disease, where the glucocorticoid receptor modulator ADC ABBV-154 met placebo-controlled efficacy endpoints in rheumatoid arthritis but was discontinued because its benefit-risk profile did not differentiate it from existing biologic therapies. Full article

Background and Objectives: Reliable pretreatment biomarkers to guide treatment selection in HER2-positive metastatic breast cancer (mBC) remain an unmet need. Systemic inflammatory indices derived from routine blood tests have emerged as accessible prognostic markers. This study evaluated the prognostic value of inflammation-based indices in patients with HER2-positive mBC treated with trastuzumab emtansine (T-DM1). Materials and Methods: In this retrospective single-center cohort study, 50 patients with HER2-positive mBC treated with T-DM1 in the second-line setting were analyzed. Overall survival (OS) and progression-free survival (PFS) were estimated using the Kaplan–Meier method. ROC analysis assessed the prognostic performance of the CRP/albumin ratio (CAO), neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), and systemic immune-inflammation index (SII). Variables associated with PFS were further evaluated using multivariable Cox regression. Results: The median follow-up was 46 months. Median OS from initial diagnosis and median PFS from T-DM1 initiation were 96 and 7 months, respectively. Metastatic pattern (p = 0.010), CNS involvement at T-DM1 initiation (p = 0.025), liver metastasis (p = 0.041), and best radiologic response (p < 0.001) were associated with PFS. ROC analysis showed modest discrimination (CAO AUC 0.694, NLR 0.658, PLR 0.646, and SII 0.653). In multivariable analysis, best radiologic response to T-DM1 was strongly associated with progression risk and appeared to reflect treatment sensitivity rather than acting as a pretreatment predictor. Conclusions: T-DM1 provided meaningful disease control in this real-world cohort. Treatment response was the main determinant of progression, while baseline inflammatory markers offered modest complementary prognostic value. These findings may aid patient selection for T-DM1, particularly in settings with limited access to trastuzumab deruxtecan. Full article

Purpose: Male breast cancer (maleBC) is an orphan disease. Aside from age, risk factors include genetic mutations and conditions like Klinefelter syndrome or other reasons of hypogonadism. Treatment is based on standards in women, but biological differences may exist, with maleBC exhibiting higher rates of hormone-receptor expression. Limiting data exists regarding the rate of low/ultralow HER2 expression, a predictive biomarker for the antibody–drug conjugate (ADC) trastuzumab deruxtecan (T-DXd) in HER2-negative disease in women. Materials and Methods: We conducted a retrospective single-center analysis of clinicopathological features of maleBC at a tertiary cancer center. We identified a cohort of 57 maleBC patients, described demographic, pathological, prognostic and surgical and systemic treatment data and evaluated frequencies of low and ultralow HER2 expression. Results: The mean age was 64.3 (SE ± 1.79) years; 94.7% (n = 54) of patients presented with early/nonmetastatic breast cancer and 40.7% (22 of 54) of patients exhibited nodal involvement. Most patients (92.6%, 50 of 54 patients) had luminal disease and approximately one third of patients received chemotherapy. Endocrine therapy was administered in 87.7% (n = 50/57) of cases. For 52 of the patients included, full receptor status data including HER2 IHC scoring and/or histological specimens were available. IHC slides of tumor specimens from 24 patients with either historically reported “HER2 negative” or “HER2 0” expression were available for reassessment; 79.2% (n = 19 of 24) of these tumors exhibited either HER2-low or -ultralow expression. In the whole cohort, rates of HER2-low and -ultralow expression were 75.0% (39 of 52) and 5.8% (3 of 52 patients), respectively. The median follow-up was 7 years. Six deaths occurred in the total population (n = 57). The median event-free survival (EFS) was 8.39 years (95% CI 7.36–11.35). No statistically significant associations were observed between HER2 expression categories and clinicopathological variables including grade, ER status, nodal status, genetic variant status, age, Ki67 index, or overall survival events. Conclusions: In this cohort of maleBC patients, high rates of combined HER2-low and -ultralow expression were observed upon reassessment of tumors with historically negative HER2 status, shedding light on potential ADC eligibility in male breast cancer. Full article

This review discusses the role of human epidermal growth factor receptor 2 (HER2/ERBB2) as a key oncogenic driver in non-small cell lung cancer (NSCLC), including exon 20 activating mutations, gene amplification, and protein overexpression. These forms differ in their biological effects and predictive value, but HER2 mutations, especially exon 20 insertions, are the primary oncogenic mechanism. Regarding diagnosis, Next-Generation Sequencing (NGS) is used to identify mutations, whereas Immunohistochemistry (IHC) and in situ hybridization are used to assess HER2 expression. Concerning treatment, in advanced HER2-positive, Non-Squamous NSCLC tumors, the first-line treatment is Platinum-based + Pemetrexed chemotherapy, with or without immunotherapy, because no HER2-targeted antibody therapy has yet been approved for initial treatment. After progression, HER2-targeted antibody-drug conjugates like Trastuzumab-Deruxtecan and Ado Trastuzumab-Emtansine may offer patients clinical benefits. New HER2-selective tyrosine kinase inhibitors, such as zongertinib and sevabertinib, have shown promising results, including patients previously treated with antibody–drug conjugates (ADCs). Recent advances, including next-generation ADCs such as SHR-A1811 and A166, and bispecific antibodies, such as zenocutuzumab for NRG1 fusion–positive disease, which are also expanding treatment options. Overall, advances in diagnostics and new targeted therapies are changing how HER2-altered NSCLC is treated and are helping to make care more personalized. Full article

Human epidermal growth factor receptor 2 (HER2) dysregulation contributes to tumorigenesis in gastric and gastroesophageal junction adenocarcinomas (GC/GEJ). HER2 overexpression has been associated in multiple cohorts with aggressive behavior and poor outcomes. While HER2 amplification has long guided therapy in HER2-positive disease, antibody–drug conjugates (ADCs) have shifted attention toward the HER2-low category, typically defined as immunohistochemistry (IHC) 1+ or IHC 2+ with negative in situ hybridization (ISH). This narrative review integrates evidence from the peer-reviewed literature, current testing recommendations, and registered clinical trials. It clarifies practical issues in HER2-low assessment and maps the evolving therapeutic landscape of HER2-targeted ADCs including rational combination strategies that may extend benefit beyond conventionally HER2-positive tumors. A cross-tumor perspective contrasts GC/GEJ testing and biology with the breast cancer paradigm and summarizes the importance of HER2-low expression in non-gastric malignancies. Finally, we discuss the therapeutic strategies in HER2-low GC/GEJ and highlight key safety and monitoring considerations for HER2-directed ADCs. Full article

Treatment-refractory rectal cancer liver metastasis represents a major therapeutic challenge, particularly in the absence of actionable genomic biomarkers. Functional precision oncology approaches integrating genomic profiling with patient-derived organoid (PDO) drug testing may provide biologically informed therapeutic prioritization. A 50-year-old female patient with KRAS/TP53-mutant, microsatellite-stable (MSS) rectal adenocarcinoma refractory to FOLFIRINOX was enrolled. A liver metastasis from a treatment-refractory rectal cancer patient was processed to establish three-dimensional patient-derived organoids. Histopathological concordance was assessed using H&E and p53 immunohistochemistry. Comprehensive genomic profiling was performed using a 637-gene targeted next-generation sequencing panel, enabling detection of single-nucleotide variants, indels, copy number variations, microsatellite instability, and tumor mutational burden. Functional drug sensitivity profiling was conducted in parallel 2D and 3D platforms using a customized 17-agent panel, followed by exploratory combinatorial validation. The organoids demonstrated high phenotypic and genomic concordance with the parental tumor, preserving key driver alterations (KRAS^A146T, TP53^R175H, APC frameshifts, CCNE1 amplification), microsatellite stability, and low tumor mutational burden (TMB: 6.37 mut/Mb). Functional screening identified selective sensitivity to bevacizumab (IC₅₀: 0.130 μM), doxorubicin (IC₅₀: 0.570 μM), carboplatin (IC₅₀: 0.950 μM), and topotecan (IC₅₀: 1.600 μM) in the 3D organoid model, with consistent cross-platform validation. An exploratory combination assay further supported enhanced viability suppression under bevacizumab-based regimens. Critically, at the time of manuscript preparation, the patient demonstrated radiological disease stabilization under bevacizumab plus trastuzumab deruxtecan, consistent with the organoid-derived response profile. These findings highlight the capacity of integrated genomic and organoid-based profiling to uncover therapeutic vulnerabilities beyond standard biomarker assessment. This proof-of-concept case report study demonstrates the feasibility and translational relevance of an established organoid-based functional precision oncology platform for therapeutic prioritization in metastatic rectal cancer. Full article