TBCRC 048: Phase II Study of Olaparib for Metastatic Breast Cancer and Mutations in Homologous Recombination-Related Genes

Brain metastases in patients with metastatic breast cancer and BRCA1/2 mutations in cell-free DNA

PURPOSE

Brain metastases (BM) in patients with metastatic breast cancer (MBC) cause significant morbidity/mortality. A relatively high prevalence of BM is seen in patients with germline BRCA1/2 mutations. Some patients with MBC have somatic BRCA1/2 mutations but the prevalence of BM in this setting is not known.

METHODS

Here, we evaluated the prevalence and clinical and genomic characteristics of BM in patients with MBC with somatic BRCA1/2 mutations in cell-free DNA (cfDNA) using the Guardant360 assay. Clinical and genomic features of patients with somatic BRCA1/2 mutations and brain metastases, and those without brain metastases were compared using a Chi-squared test for categorical variables and Wilcoxon rank-sum test for continuous variables.

RESULTS

Of 36 patients with MBC and somatic BRCA1/2 mutations, 9 (25%) developed BM. The median time to development of BM was 6.7 months after somatic BRCA detection by cfDNA testing. Among patients with BM, somatic BRCA mutations were commonly BRCA1, clonal, and present at a higher mutant allelic fraction. The coexisting genomic landscape in patients with BM commonly included PIK3CA, TP53, MYC, EGFR, CCNE1, and KIT mutations.

CONCLUSION

A relatively high prevalence of BM in patients with MBC harboring cfDNA somatic BRCA1/2 mutations was observed. CfDNA somatic BRCA1/2 mutations may help identify patients with MBC at risk for BM. To our knowledge, this is the first report linking cfDNA somatic BRCA mutations with BM, and requires further investigation in additional datasets and studies.

Therapeutic advances and application of PARP inhibitors in breast cancer

Targeting of DNA repair pathway is the main therapeutic approach for BRCA1 and BRCA2 associated tumors, including breast cancer. BRCA1/2 genes play a pivotal role in HRR pathway. Mutations in BRCA1/2 leads to DDR deficiency, which cause the increasing of genome instability, thus rendering cancer cells vulnerable to inhibition of DNA repair related proteins, such as PARP1. Pre-clinical studies has demonstrated that cancer cells with BRCA1/2 deficient are sensitive to PARPi, which are an emerging class of small molecule drug. Several clinical trials demonstrated the promising efficacy of PARP inhibitors for BRCA1/2 mutated breast cancer patient through selectively induce synthetic lethality cancer cells. Currently, four PARP inhibitors had been approved by FDA for clinical use. PARPi demonstrated to improve progression-free survival, while resistance to PARPi is inevitable. In this review article, we highlighted the advances in the PARPi clinical trials, resistance mechanism and coping strategies in breast cancer patients. We also summarized the international guideline and recommendations on PARP inhibitor usage in breast cancer.

Identifying germline pathogenic variants in breast cancer using tumor sequencing

PURPOSE

To investigate the performance of an in-house tumor sequencing panel to identify patients with breast cancer and a germline pathogenic variant (gPV).

PATIENTS AND METHODS

Retrospective and blinded tumor sequencing analysis in 90 patients with breast cancer and prior germline genetic testing (45 non-carriers and 45 carriers of a gPV) using an in-house panel (VHIO-300). Sensitivity (S), specificity (Sp), positive predictive value (PPV), and negative predictive value (NPV) of tumor sequencing were calculated. A Cohen's kappa coefficient ≥0.80 was predefined as minimum to be reliably acceptable for clinical implementation.

RESULTS

The cohort included 84 women and 6 men with a median age of 48 years (29-84). Tumors of germline carriers were mainly stage II (47 % vs 31 %, P = 0.047), luminal B-like (56 % vs 31 %, p = 0.037) or triple negative (22 % vs 16 %, = 0.037). The in-house tumor panel identified 91 % (40/44) of the gPV. The analysis did not detect any of the 2 patients with germline large rearrangement alterations nor 2 of the 7 patients with intronic variants included. The tumor sequencing panel yielded 7 % of false positive results (ie, genetic alterations suggestive of germline origin). Hence, S was 91 %, Sp 93 % and Cohen's kappa coefficient between tumor and germline testing was 0.84 (95 % CI 0.73-0.95).

CONCLUSION

Tumor tissue sequencing with our in-house panel demonstrated an acceptable performance to identify patients with breast cancer carriers of a gPV.

The clinical and molecular landscape of breast cancer in women of African and South Asian ancestry

Addressing existing racial disparity in breast cancer is crucial to ensure equitable benefit across diverse communities. We evaluate the molecular and clinical effects of genetic ancestry in African and South Asian women compared to European using a combined cohort of 7136 breast cancer patients. We find that non-European patients present significantly earlier and die at a younger age. The African group has an increased prevalence of higher grade and hormone receptor negative disease. The South Asian group shows tendency towards lower stage at diagnosis and tumour mutational burden. We observe differences and similarities in the somatic mutational landscape, and differences in germline mutation rates relevant to genetic testing and breast cancer predisposition. Potential therapeutic candidates are identified, with a higher propensity for homologous recombination deficiency serving as a therapy response indicator. We harness breast cancer multimodal data to improve understanding of ancestry-associated differences and highlight opportunities to advance health equity.

Genomic landscape and homologous recombination repair deficiency signature in stage I-III and de novo stage IV primary breast cancers

PURPOSE

We compared genomic alterations and a homologous recombination deficiency (HRD) signature (HRDsig) in primary tumors from stage I-III to those in de novo stage IV breast cancers and from stage I-III cancers with early (<2 years after diagnosis) versus late (>2 years) recurrence.

METHODS

De-identified genomic and clinical data of primary breast cancers (stage I-III N = 910, stage IV N = 783) from the United States, the nationwide clinico-genomic database of Flatiron Health and Foundation Medicine were analyzed. Genomic results included the mutation status of 324 cancer-related genes and HRDsig, a DNA scar-based measure of HRD.

RESULTS

No significant differences were observed in the frequencies of genomic alterations across disease stages, or between stage I-III cancers with early versus late relapse. Overall, the most prevalent biomarkers were PIK3CA mutation and HRDsig positivity. HRDsig positivity was observed in 82% of germline or somatic g/sBRCA1/2 or germline PALB2 (gPALB2) mutated cancers, 13.1% in cancers with other HR-repair (HRR) gene alterations (ATM, BARD1, BRIP1, CDK12, CHEK1, CHEK2, FANCL, somatic PALB2 (sPALB2), RAD51B, RAD51C, RAD51D and RAD54L), and also in 16.5% of HRR wild-type cancers. HRDsig positivity was observed across receptor subtypes and was the highest in TNBC (30%), followed by ER+/HER2- cancers (17%), then HER2 + cancers (8.7%).

CONCLUSIONS

Early-stage (I-III) and de novo stage IV breast cancers shared a similar prevalence of targetable genomic alterations and overall genomic landscape. HRDsig identified approximately 16% of breast cancers without g/sBRCA/gPALB2 alteration that might potentially benefit from PARP inhibitors or platinum-based treatments and should be tested in future clinical studies.

Advancing breast cancer therapy in the era of molecular diagnostics

Advances in cancer biology and drug development now enable treatments tailored to individual tumor profile. Targeting specific molecular alterations marked a significant step forward in cancer care, including breast cancer. Access to these therapies is improving thanks to the implementation of molecular tumor boards and efforts to provide molecular diagnostics at sustainable costs for all. In this context, we highlight recent progress in breast cancer therapy, focusing on biomarker-driven approaches, immunotherapy, and precision medicine paving the way for increasingly personalized and effective options.

Germline pathogenic variants in DNA repair pathways: a key feature in a significant subset of translocation-associated sarcomas

Translocation-associated sarcomas (TAS) are rare, phenotypically heterogeneous, with predisposition for young adults. We aimed to investigate the clinical impact of germline pathogenic/likely pathogenic (P/LP) variants in a diverse group of TAS and to conduct a comprehensive comparative analysis of clinicopathologic features, genomic alterations, and survival outcomes. A retrospective cohort of 426 TAS patients with both tumor and germline DNA sequencing was investigated for clinical actionability of P/LP variants, and potential impact on current screening guidelines and clinical interventions. Twenty-eight patients (6.6%) carried Tier 1 germline P/LP variants (moderate to high penetrance autosomal dominant (AD) variants), while 27 (6.3%) patients carried Tier 2 variants (monoallelic autosomal recessive or low penetrance AD variants). Compared to Tier 2, Tier 1 patients were more commonly of European ancestry and had a higher frequency of first- and second-degree relatives with cancer history. Notably, the frequency of both tiers variants was lower among pediatric patients compared to older patients and differed across TAS histologies, with the highest observed in solitary fibrous tumors. All germline P/LP variants were monoallelic, dispersed across multiple genes, and enriched in DNA damage repair pathways. There was no association between the germline P/LP variants and somatic genomic profile, nor any survival impact when stratified by histotype. Our findings highlight the incidence of clinically significant germline P/LP variants in TAS is lower in pediatric patients, questioning current sarcoma genetic screening guidelines and supporting germline testing for all TAS patients. Significant interventions were triggered in 46% of Tier 1 (n = 13), including platinum-based chemotherapy and PARP inhibitors in two BRCA1/2 patients.

Neoadjuvant Paclitaxel/Olaparib in Comparison to Paclitaxel/Carboplatin in Patients with HER2-Negative Breast Cancer and HRD-Long-term Survival of the GeparOLA Study

PURPOSE

The GeparOLA study evaluated paclitaxel plus olaparib (PO) in neoadjuvant chemotherapy for patients with HER2-negative early breast cancer with homologous recombination deficiency (HRD). HRD was defined by high HRD score or germline (g)/tumor (t) BRCA1/2 mutations (g/tBRCA1/2mut). In this study, we report long-term outcome data.

PATIENTS AND METHODS

GeparOLA (NCT02789332) was a randomized, multicenter, prospective, open-label, phase II trial. Patients with HER2-negative early breast cancer with HRD with an indication for chemotherapy (cT2-cT4a-d or cT1c and cN+ or cT1c and pNSLN+ or cT1c and triple-negative breast cancer, or cT1c and Ki-67 >20%) were randomly assigned to PO or paclitaxel + carboplatin (PCb), both followed by epirubicin + cyclophosphamide. Long-term efficacy endpoints were secondary endpoints and included invasive disease-free survival (iDFS), distant disease-free survival (DDFS), and overall survival, with a planned median follow-up of >4 years.

RESULTS

Between September 2016 and July 2018, 107 patients were randomized and 106 (PO N = 69 and PCb N = 37) started treatment. The median age was 47.0 years; of all patients, 35.8% had cT1 tumors, 31.4% were cN+, 86.8% had G3 tumors, 89.6% had Ki-67 >20%, and 72.6% were triple negative. After a median follow-up of 49.8 months, 18 (15 in PO and three in PCb) iDFS events and seven (six in PO and one in PCb) deaths were reported. The 4-year iDFS (76.0% PO vs. 88.5% PCb, hazard ratio = 2.86; 95% CI, 0.83-9.90; log-rank P = 0.081), DDFS (81.2% PO vs. 93.4% PCb, hazard ratio = 3.03; 95% CI, 0.67-13.67; log-rank P = 0.129), and overall survival (89.2% PO vs. 96.9% PCb, hazard ratio = 3.27; 95% CI, 0.39-27.20; log-rank P = 0.244) tended to be inferior with olaparib. Patients without g/tBRCA1/2mut benefited from Cb (seven of 30 patients had iDFS/DDFS events in PO vs. 0/16 in PCb; log-rank P = 0.037), whereas no difference for patients with g/tBRCA1/2mut was observed (hazard ratio = 1.16, log-rank P = 0.83).

CONCLUSIONS

For HER2-negative early breast cancer with HRD, olaparib showed a tendency for inferior outcomes compared with Cb, particularly in patients without g/tBRCA1/2mut. In patients with g/tBRCA1/2mut, olaparib may replace Cb.

Functional characterization of all CDKN2A missense variants and comparison to in silico models of pathogenicity

Interpretation of variants identified during genetic testing is a significant clinical challenge. In this study, we developed a high-throughput CDKN2A functional assay and characterized all possible human CDKN2A missense variants. We found that 17.7% of all missense variants were functionally deleterious. We also used our functional classifications to assess the performance of in silico models that predict the effect of variants, including recently reported models based on machine learning. Notably, we found that all in silico models performed similarly when compared to our functional classifications with accuracies of 39.5-85.4%. Furthermore, while we found that functionally deleterious variants were enriched within ankyrin repeats, we did not identify any residues where all missense variants were functionally deleterious. Our functional classifications are a resource to aid the interpretation of CDKN2A variants and have important implications for the application of variant interpretation guidelines, particularly the use of in silico models for clinical variant interpretation.

Expert Perspectives on Controversies and Critical Knowledge Gaps in Breast Cancer Management: Proceedings of the First Bridging the Gaps in Breast Cancer Symposium

PURPOSE

Breast cancer is the most common type of cancer for women in the United States and accounts for nearly 25% of all cancers and 16% of cancer deaths worldwide. New treatment options continue to emerge offering improved management options for patients with breast cancer. However, as these new treatments become available, clinicians are left with many questions regarding how to best utilize these treatments and improve outcomes for patients with breast cancer.

MATERIALS AND METHOD

The Bridging the Gaps in Breast Cancer panel was assembled to address challenges in the management of breast cancer. Bridging the Gaps in Breast Cancer co-chairs and session moderators identified areas of controversy and uncertainty in breast cancer management and were responsible for organizing the presentations and discussion with the expert panel of faculty throughout the meeting.

RESULTS

The Bridging the Gaps in Breast Cancer panel discussions are presented. Key critical knowledge gaps surrounding the evolving breast cancer treatment landscape identified include how to identify which patients will benefit the most from therapeutic intervention, the mechanism of resistance to newly approved therapies, which therapies may be safely omitted from a treatment regimen without harm to the patient, and the most important metric(s) in defining successful treatment in various stages and subtypes of breast cancer.

CONCLUSIONS

The treatment armamentarium for the management of breast cancer continues to grow and evolve. With those new treatment options, new questions continue to arise for clinicians. Future studies are needed to address these critical gaps in knowledge about how to best utilize treatments for improved patient outcomes.

Exploring the Prognostic and Predictive Impact of Genomic Loss of Heterozygosity and Homologous Recombination Deficiency Alterations in Patients With Metastatic Colorectal Cancer

PURPOSE

Genomic loss-of-heterozygosity (gLOH) consists in the loss of chromosomal regions and is associated with homologous recombination repair (HRR) system deficiency. We explored the role of gLOH and HRR-related gene alterations in metastatic colorectal cancer (mCRC).

METHODS

FoundationOne CDx assay was used to determine the percentage of gLOH and the presence of alterations in 27 HRR-related genes in archival chemo-naïve tumor tissues of patients with mCRC treated with first-line oxaliplatin- or irinotecan-based doublets and triplet ± anti-PD-L1.

RESULTS

Overall, 243 samples were analyzed. None of the nine deficient mismatch repair/microsatellite instability high tumors were gLOH-high, while 16 (7%) of 234 proficient mismatch repair/microsatellite stable (pMMR/MSS) tumors were gLOH-high. In the pMMR/MSS population, six (3%) and 18 (8%) had at least a biallelic or monoallelic HRR-related gene alteration, respectively. Among patients receiving FOLFOXIRI alone (n = 68) or with an anti-PD-L1 (N = 90), higher benefit from the addition of the immune checkpoint inhibitor (ICI) was observed in the gLOH-high subgroup (n = 12), in terms of both progression-free survival (PFS; Pint = .02) and overall survival (OS; Pint = .03). No differences in PFS or OS were reported between patients treated with first-line oxaliplatin- (n = 40) versus irinotecan-based doublets (n = 25) or with the triplet FOLFOXIRI (n = 68) versus doublets (n = 65), according to the gLOH status. Among patients not receiving an anti-PD-L1, longer PFS was observed in the gLOH-low group (n = 138) versus the gLOH-high (n = 6) group (5.1 v 12.1 months; hazard ratio, 8.73 [95% CI, 3.64 to 20.9]; P < .001), and this was confirmed in the multivariate analysis (P < .001). No prognostic impact of monoallelic or biallelic HRR-related gene alterations was shown.

CONCLUSION

In pMMR/MSS mCRC, gLOH-high was associated with worse prognosis and higher benefit from the addition of anti-PD-L1 agents to chemotherapy. If confirmed in larger series, these results may inform the design of clinical trials.

Prevalence and clinical impact of germline pathogenic variants in breast cancer: a descriptive large single-center study

BACKGROUND

Germline (likely) pathogenic variants (PVs) are identified in 5%-10% of patients with breast cancer (BC) and play a critical role in guiding clinical management, including the use of targeted therapies such as poly (ADP-ribose) polymerase (PARP) inhibitors (PARPi). High-risk genes such as BRCA1, BRCA2, and PALB2, and moderate-risk genes such as CHEK2 and ATM, influence BC risk and treatment decisions. This study evaluates the prevalence and clinical impact of PVs in a large consecutive cohort.

MATERIALS AND METHODS

A retrospective analysis was conducted on 912 individuals with BC who underwent germline testing at the Hospital Clinic of Barcelona from 2016 to 2023. Genetic testing for 14 BC and Lynch syndrome genes was carried out using the TruSight Hereditary Cancer Panel. Statistical analyses were carried out to assess associations between germline results and clinical characteristics, including eligibility for PARPi therapy.

RESULTS

Of the 912 individuals, 129 (14.1%) had a PV, with BRCA2 (31.8%) and BRCA1 (24%) being the most frequently altered genes. Additionally, 16.2% carried variants of uncertain significance, most commonly in ATM and BRCA2 genes. Patients with PV were younger compared with PV-negative individuals (median age: 43.5 versus 48.2 years, P = 0.006), more likely to have bilateral BC (13.3% versus 5.8%, P = 0.002), and more frequently diagnosed with triple-negative BC (TNBC; 28.7% versus 20.8%, P = 0.046). Of those with PVs, 39.1% completed a bilateral mastectomy, 36.7% had a risk-reducing salpingo-oophorectomy, and 22.7% had both surgeries. PV detection was associated with higher stages at diagnosis (stage IV: 13.0% versus 5.9%, P < 0.001). In the metastatic cohort, 12.9% received PARPi therapy, with 80.7% harboring BRCA1/2 PVs. In early BC, 13.1% met the criteria for adjuvant PARPi.

CONCLUSIONS

The identification of germline PVs significantly influences surgical decisions and systemic therapies. Genetic testing for patients with BC optimizes care, particularly in selecting candidates for PARPi in both early and advanced BC, improving management and prevention strategies.

Beyond failure of endocrine-based therapies in HR+/HER2 negative advanced breast cancer: What before chemotherapy? A glimpse into the future

Despite the impressive improvements achieved by endocrine therapy and CDK4/6 inhibitors (CDK4/6i) and the forthcoming availability of alternative endocrine manipulations and targeted therapies, hormone-receptor positive/HER2 negative (HR+/HER2-) advanced breast cancer (ABC) is almost inevitably destined to become endocrine- refractory. At this time chemotherapy has been recently challenged and partly replaced by new targeted options as antibody-drug conjugated (ADCs). Trastuzumab-deruxtecan has been proven meaningfully superior to chemotherapy either in 1st and later lines after progression to CDK4/6i in HER2-low ABC and results with other ADCs as Sacituzumab Govitecan and Datopotamab-deruxtecan are promising, but the definition of cross-resistance between these drugs sharing either antibody or payload is crucial before implementing them in a useful sequence. While PARP inhibitors are the standard 2nd line in patients with gBRCA mutation, it is not still known whether patients with mutations of PALB2 or of other homologous recombinant defect (HRD)-related genes will benefit of the same treatment. On the other hand, the results obtained with immune checkpoint inhibitors (ICIs) in HR+ /HER2-ABC contrarily to the early setting are disappointing up to now, but investigations of ICIs in combination with other targeted drugs which may increase immune response and the search for better markers of activity are under way. Moreover the anticipation in upfront treatment of ADCs or PARPi in patients with features of putative endocrine resistance and/or of less sensitiviy to CDK4/6i and the choice of therapy in patients recurring during or soon after adjuvant CDK4/6i and olaparib represent further challenges for the future.

Post-progression treatment options after CDK4/6 inhibitors in hormone receptor-positive, HER2-negative metastatic breast cancer

The combination of cyclin-dependent kinase 4/6 inhibitors (CDK4/6i) and endocrine therapy (ET) is the standard first-line treatment for hormone receptor-positive (HR + ) and HER2-negative metastatic breast cancer (mBC). Despite their efficacy, resistance inevitably develops, necessitating alternative therapeutic strategies post-progression. This review explores current and emerging treatment options following progression on CDK4/6i, focusing on endocrine therapies, targeted therapies, combination approaches, and the continued use of CDK4/6i. Endocrine therapies, including fulvestrant and novel oral selective estrogen receptor degraders (SERDs) like elacestrant, show promise, especially in patients with ESR1 mutations. Targeted therapies such as PI3K/AKT/mTOR inhibitors, exemplified by alpelisib and capivasertib, offer potential by addressing downstream signaling pathways involved in resistance. Additionally, FGFR inhibitors like erdafitinib are under investigation for their role in overcoming specific resistance mechanisms. Combination strategies involving CDK4/6 inhibitors with immune checkpoint inhibitors or other targeted agents are also being explored, with early trials suggesting possible synergistic effects, although further validation is required. Continuation of CDK4/6 inhibitors beyond progression has shown potential benefits in selected patients, but the data are heterogeneous, and further studies are needed to clarify their role. While chemotherapy remains a standard option for patients who progress on these treatments, the goal is to delay its use through the effective utilization of endocrine and targeted therapies. Understanding resistance mechanisms and tailoring treatment to individual patient profiles is crucial for optimizing outcomes. Ongoing clinical trials are expected to provide deeper insights, guiding the development of more effective post-progression therapeutic strategies. This evolving landscape highlights the need for continuous research and individualized patient care to improve survival and quality of life in HR + mBC patients.

Real-World Evidence on Prescribing Patterns and Clinical Outcomes of Metastatic Breast Cancer Patients Treated with PARP Inhibitors: The Mayo Clinic Experience

PURPOSE

This study evaluates real-world outcomes, toxicities, and prescribing patterns of PARP inhibitors (PARPis) for the treatment of metastatic breast cancer (MBC).

PATIENTS AND METHODS

Electronic health records of 62 MBC patients treated with olaparib (n = 48) or talazoparib (n = 14) at Mayo Clinic System between 2017 and 2022 were analyzed. Time-to-treatment-failure (TTF) was assessed utilizing the Kaplan-Meier method. Predictors of TTF were identified in a multivariate Cox-proportional hazard regression model adjusting for relevant tumor and demographic characteristics.

RESULTS

Among 62 patients who received PARPis for MBC, 55 had germline (g) pathogenic variants (PVs) (gBRCA1 = 24, gBRCA2 = 26, and gPALB2 = 4) and 8 patients had somatic (s) PVs (sBRCA1 = 4, sBRCA2 = 2, sATM = 1, sCDKN2A = 1). Median TTF in the gBRCA1, gBRCA2, and gPALB2 PV carriers were 7, 8, and 9 months, respectively (P = .37). Complete or partial responses were observed among 51.8% of patients with gBRCA or gPALB2 PVs. In multivariate analysis, HER2 positivity (hazard ratio, HR: 4.9, P = .007) and somatic PVs in homologous recombination repair (HRR) genes other than BRCA (sATM or sCDKN2A) (HR: 11.7, P = .01) were associated with a shorter TTF. No significant difference in TTF was observed by the type of PARPi, estrogen and progesterone receptor status, age, or number of prior therapies. Eight (16.7%) patients receiving olaparib and seven (50%) receiving talazoparib required dose reductions due to toxicities.

CONCLUSIONS

In real-world practice, PARPis are well-tolerated with promising TTF in gBRCA1/2 and gPALB2 carriers. Further studies will delineate the clinical efficacy of PARPis in other MBC subsets, such as sBRCA mutations, HER2-positive disease, and CNS metastasis.

[18F]FluorThanatrace PET imaging as a biomarker of response to PARP inhibitors in breast cancer

BACKGROUND

Poly (ADP-ribose) polymerase inhibitors (PARPi) are approved for Breast Cancer gene (BRCA)-mutant HER2- breast cancer, and there is clinical interest in expanding indications to include homologous recombination deficient (HRD) breast cancers. Yet, response in these populations remains variable, suggesting clinical utility in developing a better biomarker to select patients for PARPi and predict response. Here, we evaluate a radiolabeled PARPi, [18F]FluorThanatrace ([18F]FTT), as a functional biomarker of PARPi response in breast cancer.

METHODS

A single-arm prospective observational trial was conducted at the University of Pennsylvania. [18F]FTT-PET uptake was measured in 24 women with untreated primary breast cancer and correlated with tumor HRD score. In a separate cohort of ten subjects with metastatic HER- breast cancer, [18F]FTT-PET uptake was measured at baseline and after a short interval on a PARPi (a measure of drug-target engagement) and correlated to progression free survival (PFS).

RESULTS

Here we show that baseline [18F]FTT-PET uptake does not correlate to HRD tissue score, supporting that [18F]FTT provides distinct information from genetic features. Baseline [18F]FTT-PET uptake and the change in uptake from baseline to after PARPi initiation significantly correlates to PFS in woman with breast cancer who received a PARPi (ρ = 0.74, P = 0.023 and ρ = -0.86, P = 0.012, respectively).

CONCLUSIONS

These early results suggest the potential of [18F]FTT-PET to select patients for PARPi treatment and monitor in vivo pharmacodynamics after therapy start. Absence of association with HRD scores supports [18F]FTT uptake as a novel measure that may be leveraged as a biomarker. Further studies are warranted.

PALB2 germline pathogenic variants: frequency, clinical features, and functional analysis of c.3350+5G>A variant in 3987 Korean cancer patients

BACKGROUND

Germline PALB2 variants increase the risks of various cancers. However, these have not been comprehensively investigated in Korean patients with cancer. Our study aimed to evaluate the prevalence and clinical characteristics of PALB2 germline variants in Korean patients with cancer and compare these findings with existing data.

PATIENTS AND METHODS

We analyzed the clinicopathological and germline next-generation sequencing data of 3987 patients with cancer from the National Cancer Center in Korea. Additionally, we carried out functional analysis of the PALB2 splicing variant, c.3350+5G>A.

RESULTS

A total of 104 patients presented PALB2 germline variants with eight pathogenic variants (PVs), 14 likely pathogenic variants (LPVs), and 82 variants of uncertain significance (VUS). PALB2 PV/LPVs were detected at an overall frequency of 0.6% (22/3987) across all patients. Among patients with PV/LPVs, 95.5% were women, and 19 and 3 carriers were diagnosed with breast and ovarian cancer, respectively. Further, we reclassified c.3350+5G>A as a PV rather than VUS, according to the American College of Medical Genetics and Genomics guidelines. Patients with PALB2 PV/LPVs had a younger age at first cancer diagnosis (44.6 ± 10.1 years versus 50.2 ± 12.0 years, P = 0.019) and were more likely to have multiple primary organ cancer diagnoses (22.7% versus 8.3%, P = 0.032) compared with those without these variants.

CONCLUSION

Age at first cancer diagnosis and the presence of multiple primary organ cancers are key risk factors for suspected germline PALB2 PV. Hence, strategies are required to improve adherence to the National Comprehensive Cancer Network guidelines for cancer screening and family genetic testing among Korean patients with cancer.

Cell-free tumor DNA analysis in advanced or metastatic breast cancer patients: mutation frequencies, testing intention, and clinical impact

Background

Circulating cell-free tumor DNA (ctDNA) provides a non-invasive approach for assessing somatic alterations. The German PRAEGNANT registry study aims to explore molecular biomarkers and investigate their integration into clinical practice. In this context, ctDNA testing was included to understand the motivations of clinicians to initiate testing, to identify somatic alterations, and to assess the clinical impact of the results obtained.

Methods

Patients with advanced/metastatic breast cancer were prospectively enrolled in the Prospective Academic Translational Research Network for the Optimization of Oncological Health Care Quality in the Adjuvant and Advanced/Metastatic Setting (PRAEGNANT study; NCT02338167). The FDA-approved and CE-marked GUARDANT360 CDx test was used to assess somatic alterations. A ctDNA-analysis report was provided to the treating physician along with a questionnaire about the intent for testing and the clinical implications of test results.

Results

ctDNA from 49 patients was analyzed prospectively: 37 (76%) had at least one somatic alteration in the analyzed geneset; 14 patients (29%) harbored alterations in TP53, 12 (24%) in PIK3CA, and 6 (12%) in ESR1. Somatic mutations in BRCA1 or BRCA2 were detected in 3 (6%) and 4 (8%) patients, respectively, and 59% of patients had hormone receptor-positive, human epidermal growth factor receptor 2-negative breast cancer. Questionnaires regarding test intentions and clinical impact were completed for 48 (98%) patients. These showed that ctDNA testing influenced treatment decisions for 35% of patients.

Discussion

The high prevalence of somatic alterations in TP53, PIK3CA, ESR1, and BRCA1/2 genes, identified by ctDNA genotyping, highlights their potential as biomarkers for targeted therapies. Detection of specific mutations affected treatment decisions, such as eligibility for alpelisib, and might further facilitate treatment with e.g. elacestrant or capiversatib in future treatment lines.

Pathological diagnosis of central nervous system tumours in adults: what's new?

In the course of the last decade, the pathological diagnosis of many tumours of the central nervous system (CNS) has transitioned from a purely histological to a combined histological and molecular approach, resulting in a more precise 'histomolecular diagnosis'. Unfortunately, translation of this refinement in CNS tumour diagnostics into more effective treatment strategies is lagging behind. There is hope though that incorporating the assessment of predictive markers in the pathological evaluation of CNS tumours will help to improve this situation. The present review discusses some novel aspects with regard to the pathological diagnosis of the most common CNS tumours in adults. After a brief update on recognition of clinically meaningful subgroups in adult-type diffuse gliomas and the value of assessing predictive markers in these tumours, more detailed information is provided on predictive markers of (potential) relevance for immunotherapy especially for glioblastomas, IDH-wildtype. Furthermore, recommendations for improved grading of meningiomas by using molecular markers are briefly summarised, and an overview is given on (predictive) markers of interest in metastatic CNS tumours. In the last part of this review, some 'emerging new CNS tumour types' that may occur especially in adults are presented in a table. Hopefully, this review provides useful information on 'what's new' for practising pathologists diagnosing CNS tumours in adults.

A pan-tumor review of the role of poly(adenosine diphosphate ribose) polymerase inhibitors

Poly(adenosine diphosphate ribose) polymerase (PARP) inhibitors, such as olaparib, talazoparib, rucaparib, and niraparib, comprise a therapeutic class that targets PARP proteins involved in DNA repair. Cancer cells with homologous recombination repair defects, particularly BRCA alterations, display enhanced sensitivity to these agents because of synthetic lethality induced by PARP inhibitors. These agents have significantly improved survival outcomes across various malignancies, initially gaining regulatory approval in ovarian cancer and subsequently in breast, pancreatic, and prostate cancers in different indications. This review offers a comprehensive clinical overview of PARP inhibitor approvals, emphasizing their efficacy across different cancers based on landmark phase 3 clinical trials.

Functional characterization of all CDKN2A missense variants and comparison to in silico models of pathogenicity

Interpretation of variants identified during genetic testing is a significant clinical challenge. In this study, we developed a high-throughput CDKN2A functional assay and characterized all possible CDKN2A missense variants. We found that 17.7% of all missense variants were functionally deleterious. We also used our functional classifications to assess the performance of in silico models that predict the effect of variants, including recently reported models based on machine learning. Notably, we found that all in silico models performed similarly when compared to our functional classifications with accuracies of 39.5-85.4%. Furthermore, while we found that functionally deleterious variants were enriched within ankyrin repeats, we did not identify any residues where all missense variants were functionally deleterious. Our functional classifications are a resource to aid the interpretation of CDKN2A variants and have important implications for the application of variant interpretation guidelines, particularly the use of in silico models for clinical variant interpretation.

Advancements in clinical research and emerging therapies for triple-negative breast cancer treatment

Triple-negative breast cancer (TNBC), defined by the lack of estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor 2 (HER2) expression, is acknowledged as the most aggressive form of breast cancer (BC), comprising 15%-20% of all primary cases. Despite the prevalence of TNBC, effective and well-tolerated targeted therapies remain limited, with chemotherapy continuing to be the mainstay of treatment. However, the horizon is brightened by recent advancements in immunotherapy and antibody-drug conjugates (ADCs), which have garnered the U.S. Food and Drug Administration (FDA) approval for various stages of TNBC. Poly (ADP-ribose) polymerase inhibitors (PARPi), particularly for TNBC with BRCA mutations, present a promising avenue, albeit with the challenge of resistance that must be addressed. The success of phosphoinositide-3 kinase (PI3K) pathway inhibitors in hormone receptor (HR)-positive BC suggests potential applicability in TNBC, spurring optimism within the research community. This review endeavors to offer a comprehensive synthesis of both established and cutting-edge targeted therapies for TNBC. We delve into the specifics of PARPi, androgen receptor (AR) inhibitors, Cancer stem cells (CSCs), PI3K/Protein Kinase B (AKT)/mammalian target of rapamycin (mTOR), the transforming growth factor-beta (TGF-β), Ntoch, Wnt/β-catenin, hedgehog (Hh) pathway inhibitors, Epigenetic target-mediated drug delivery, ADCs, immune checkpoint inhibitors (ICIs)and novel immunotherapeutic solutions, contextualizing TNBC within current treatment paradigms. By elucidating the mechanisms of these drugs and their prospective clinical applications, we aim to shed light on the challenges and underscore the beacon of hope that translational research and innovative therapies represent for the oncology field.

Clinical Impact of Constitutional Genomic Testing on Current Breast Cancer Care

The most commonly diagnosed cancer in women worldwide is cancer of the breast. Up to 20% of familial cases are attributable to pathogenic mutations in high-penetrance (BReast CAncer gene 1 [BRCA1], BRCA2, tumor protein p53 [TP53], partner and localizer of breast cancer 2 [PALB2]) or moderate-penetrance (checkpoint kinase 2 [CHEK2], Ataxia-telangiectasia mutated [ATM], RAD51C, RAD51D) breast-cancer-predisposing genes. Most of the breast-cancer-predisposing genes are involved in DNA damage repair via homologous recombination pathways. Understanding these pathways can facilitate the development of risk-reducing and therapeutic strategies. The number of breast cancer patients undergoing testing for pathogenic mutations in these genes is rapidly increasing due to various factors. Advances in multigene panel testing have led to increased detection of pathogenic mutation carriers at high risk for developing breast cancer and contralateral breast cancer. However, the lack of long-term clinical outcome data and incomplete understanding of variants, particularly for moderate-risk genes limits clinical application. In this review, we have summarized the key functions, risks, and prognosis of breast-cancer-predisposing genes listed in the National Health Service (NHS) England National Genomic Test Directory for inherited breast cancer and provide an update on current management implications including surgery, radiotherapy, systemic treatments, and post-treatment surveillance.

Optimizing therapeutic approaches for HR+/HER2- advanced breast cancer: clinical perspectives on biomarkers and treatment strategies post-CDK4/6 inhibitor progression

This review offers an expert perspective on biomarkers, CDK4/6 inhibitor efficacy, and therapeutic approaches for managing hormone receptor-positive (HR+), human epidermal growth factor receptor-negative (HER2-) advanced breast cancer (ABC), particularly after CDK4/6 inhibitor progression. Key trials have demonstrated that combining CDK4/6 inhibitors with endocrine therapy (ET) significantly improves progression-free survival (PFS), with median durations ranging from 14.8 to 26.7 months, and overall survival (OS), with median durations reaching up to 53.7 months. Actionable biomarkers, such as PIK3CA and ESR1 mutations, have emerged as pivotal tools to guide second-line treatment decisions, enabling the use of targeted therapies like alpelisib and elacestrant and emphasizing the important role of biomarkers in guiding the selection of therapy. This overview aims to provide clinicians with a practical and up-to-date framework to inform treatment decisions and improve patient care in the context of this challenging disease. Additionally, we review emerging biomarkers and novel treatment strategies to address this difficult clinical landscape.

Molecular Basis of Breast Tumor Heterogeneity

Breast cancer (BC) is a profoundly heterogenous disease, with diverse molecular, histological, and clinical variations. The intricate molecular landscape of BC is evident even at early stages, illustrated by the complexity of the evolution from precursor lesions to invasive carcinoma. The key for therapeutic decision-making is the dynamic assessment of BC receptor status and clinical subtyping. Hereditary BC adds an additional layer of complexity to the disease, given that different cancer susceptibility genes contribute to distinct phenotypes and genomic features. Furthermore, the various BC subtypes display distinct metabolic demands and immune microenvironments. Finally, genotypic-phenotypic correlations in special histologic subtypes of BC inform diagnostic and therapeutic approaches, highlighting the significance of thoroughly comprehending BC heterogeneity.

Molecular heterogeneity and MYC dysregulation in triple-negative breast cancer: genomic advances and therapeutic implications

Triple-negative breast cancer (TNBC) is characterized by a diverse range of molecular features that have been extensively studied. MYC plays a critical role in regulating metabolism, differentiation, proliferation, cell growth, and apoptosis. Dysregulation of MYC is associated with poor prognosis and contributes to the development and progression of breast cancer. A particularly intriguing aspect of TNBC is its association with tumors in BRCA1 mutation carriers, especially in younger women. MYC may also contribute to resistance to adjuvant treatments. For TNBC, targeting MYC-regulated pathways in combination with inhibitors of other carcinogenic pathways offers a promising therapeutic approach. Several signaling pathways regulate TNBC, and targeting these pathways could lead to effective therapeutic strategies for breast cancer. Advances in genomic tools, such as CRISPR-Cas9, next-generation sequencing, and whole-exome sequencing, are revolutionizing breast cancer diagnoses. These technologies have significantly enhanced our understanding of MYC oncogenesis, particularly through CRISPR-Cas9 and NGS. Targeting MYC and its partner MAX could provide valuable insights into TNBC. Moreover, the therapeutic potential of targeting MYC-driven signaling mechanisms and their interactions with other oncogenic pathways, including PI3K/AKT/mTOR and Wnt/β-catenin, is increasingly recognized. Next-generation sequencing and CRISPR-Cas9 represent significant breakthroughs in genomic tools that open new opportunities to explore MYC's role in TNBC and facilitate the development of personalized treatment plans. This review discusses the future clinical applications of personalized treatment strategies for patients with TNBC.

Management of individuals with heterozygous germline pathogenic variants in ATM: A clinical practice resource of the American College of Medical Genetics and Genomics (ACMG)

PURPOSE

ATM germline pathogenic variants (GPVs) are associated with a moderately increased risk of female breast cancer, pancreatic cancer, and prostate cancer. Resources for managing ATM heterozygotes in clinical practice are limited.

METHODS

An international workgroup developed a clinical practice resource to guide management of ATM heterozygotes using peer-reviewed publications and expert opinion.

RESULTS

Although ATM is a moderate (intermediate) penetrance gene, cancer risks may be considered as a continuous variable, influenced by family history and other modifiers. ATM GPV heterozygotes should generally be offered enhanced breast surveillance according to their personalized risk estimate and country-specific guidelines and, generally, risk-reducing mastectomy is not recommended. Prostate cancer surveillance should be considered. Pancreatic cancer surveillance should be considered based on assessment of family history, ideally as part of a clinical trial, with existence of country-specific guidelines. For ATM GPV heterozygotes who develop cancer, radiation therapy decisions should not be influenced by the genetic result. Although poly-adenosine diphosphate ribose polymerase inhibitors are licensed for use in metastatic castration-resistant prostate cancer and ATM GPVs, the evidence-base is currently weak.

CONCLUSION

Systematic prospective data collection is needed to establish the spectrum of ATM-associated cancer and determine the outlines of surveillance, response to cancer treatment, and survival.

Disparities in Hereditary Genetic Testing in Patients with Triple Negative Breast Cancer

Triple-negative breast cancer (TNBC) is an aggressive subtype of breast cancer that disproportionately affects younger females, non-Hispanic Black women, Hispanic women, and women with the BRCA1 gene mutation. Hereditary genetic testing is particularly important in this population to assess preventative and treatment strategies, however access to genetic testing is variable. A qualitative review was performed to evaluate barriers to genetic testing for patients with TNBC. Mutations common in breast cancer are reviewed along with updated guidelines on management strategies, including the ability to include PARP inhibitors as a treatment strategy. Barriers to genetic testing are multifactorial, with non-Hispanic Black women being tested less often than other groups. The disparity is even further represented by the limited number of non-Hispanic Black patients with TNBC who receive risk-reducing surgery or targeted systemic therapy. Eliminating barriers to genetic testing can allow us to support guideline-directed care for patients with TNBC at higher risk for genetic mutations.

Clinical Impact of Somatic Genomic Testing on Breast Cancer Care

Developments in our understanding of the molecular biology of breast cancer have had a direct impact on the investigations needed to provide optimal breast cancer care. Somatic genomic tests are now used routinely to inform decisions regarding adjuvant chemotherapy use in selected early breast cancer patients, and to identify patients with advanced disease who can potentially benefit from novel targeted agents. In this overview, we describe the somatic genomic tests currently available within the National Health Service (NHS) for early and advanced breast cancer patients. We review the underlying biology and the evidence base for clinical utility of these tests in routine clinical practice. In addition, we identify the somatic genomic biomarkers currently in use in breast cancer clinical trials that are most likely to influence future breast cancer management. We also consider the challenges associated with tissue-based genomic testing in advanced breast cancer and the role of circulating tumour deoxyribonucleic acid (ctDNA) testing.

Homologous recombination deficiency (HRD) diagnostics: underlying mechanisms and new perspectives

Homologous recombination deficiency (HRD) is considered a universal and effective sign of a tumor's sensitivity to poly(ADP-ribose) polymerase (PARP) inhibitors. HRD diagnostics have undergone several stages of transformations: from detection of point mutations in HR-related genes and large regions with loss of heterozygosity detected using single-nucleotide polymorphism arrays to whole-genome signatures of single-nucleotide variants, large genomic rearrangements (LGRs), and copy number alterations. All these methods have their own advantages and limitations. HRD tests, based on signatures of LGRs and copy number alterations, show in hindsight that some progenitor cells have possessed HRD status but not the current state of the genome. The aim of this review was to compare different methods of HRD detection and mechanisms of formation of HRD-specific LGRs. In the last several years, new data appeared implying a crucial role of proteins BRCA1 and BRCA2 in the resolution of stalled replication forks that may be associated with at least some of LGRs observed in HRD-positive tumors. Reviewing current knowledge on these mechanisms, distributions of different LGR types, and limitations of sequencing technologies and algorithms of data analysis, we offer some new perspectives on HRD diagnostics. We hope that this review will help to accelerate the development of new diagnostic approaches in this important field of molecular oncology.

BRCA and Beyond: Impact on Therapeutic Choices Across Cancer

BACKGROUND

Identifying patients with gBRCAm is crucial to facilitate screening strategies, preventive measures and the usage of targeted therapeutics in their management. This review examines the evidence for the latest predictive and therapeutic approaches in BRCA-associated cancers.

CLINICAL DESCRIPTION

Data supports the use of adjuvant olaparib in patients with gBRCAm high-risk HER2-negative breast cancer. In advanced gBRCAm HER2-negative breast cancer, the PARPis talazoparib and olaparib have demonstrated benefit over standard chemotherapy. In ovarian cancer, olaparib, niraparib or rucaparib can be used as monotherapy in frontline maintenance. Olaparib and bevacizumab as a combination can also be used as frontline maintenance. In the relapsed platinum-sensitive setting, olaparib, niraparib and rucaparib are effective maintenance options in BRCAm patients who are PARPi naive. Both olaparib and rucaparib are effective options in BRCAm metastatic castrate-resistant prostate cancer (mCRPC). Evidence also exists for the benefit of PARPi combinations in mCRPC. In metastatic pancreatic cancer, olaparib can be used in gBRCAm patients who are responding to platinum chemotherapy. However, there may be a development of PARPi resistance. Understanding the pathophysiology that contributes to such resistance may allow the development of novel therapeutics. Combination therapy appears to have promising results in emerging trials. Seeking avenues for subsidised genetic testing can reduce the total costs of cancer management, leading to improve detection rates.

CONCLUSION

Identifying breast, ovarian, pancreatic and prostate cancer patients with gBRCAm plays a crucial predictive role in selecting those who will benefit significantly from PARPi therapy. The use of PARPi in gBRCAm HBOC-related cancers has resulted in significant survival benefits. Beyond BRCA1/2, HRR gene assessment and the consideration of other cancer predisposition syndromes may allow more patients to be eligible for and benefit from targeted therapies.

Breast cancer brain metastases genomic profiling identifies alterations targetable by immune-checkpoint and PARP inhibitors

Understanding the genomic landscape of breast cancer brain metastases (BCBMs) is key to developing targeted treatments. In this study, targetable genomic profiling was performed on 822 BCBMs, 11,988 local breast cancer (BC) biopsies and 15,516 non-central nervous system (N-CNS) metastases (all unpaired samples) collected during the course of routine clinical care by Foundation Medicine Inc (Boston, MA). Clinically relevant genomic alterations were significantly enriched in BCBMs compared to local BCs and N-CNS metastases. Homologous recombination deficiency as measured by BRCA1/2 alteration prevalence and loss-of-heterozygosity and immune checkpoint inhibitor (ICI) biomarkers [Tumor mutation burden (TMB)-High, Microsatellite instability (MSI)-High, PD-L1/L2)] were significantly more prevalent in BCBM than local BC and N-CNS. High PD-L1 protein expression was observed in ER-negative/HER2-negative BCBMs (48.3% vs 50.0% in local BCs, 21.4% in N-CNS). Our data highlights that a high proportion of BCBMs are potentially amenable to treatment with targeted therapeutic agents including PARP inhibitors and ICIs.

Aggressive renal cell carcinoma with somatic BRCA2 mutation-an emerging entity? A case report with literature review

Role of BRCA2 gene mutation in renal tumorigenesis remains largely unclear. There are only two case reports of renal cell carcinoma (RCC) with BRCA2 mutation, both of which showed a high-grade RCC with various architectural patterns including tubulopapillary and solid. The tumor cells were described as having eosinophilic cytoplasm and prominent nucleoli. The current study describes another case of high-grade RCC with somatic BRCA2 mutation with various architectural patterns and cells with eosinophilic cytoplasm and prominent nucleoli. Immunohistochemical staining showed co-expression of PAX8, CAIX, CD10, CK7, CK20, and P504S. This unusual co-expression of the commonly used IHC stains during the workup of RCC could serve as a potential diagnostic pitfall. Although very rare, it is important for pathologists to be aware of this form of RCC due to its aggressive clinical behavior, possibility of a germline mutation, and current therapeutic options for tumors with BRCA2 mutation.

Olaparib monotherapy in advanced triple-negative breast cancer patients with homologous recombination deficiency and without germline mutations in BRCA1/2: The NOBROLA phase 2 study

PURPOSE

To evaluate olaparib in advanced triple negative breast cancer (TNBC) patients with homologous recombination deficiency (HRD) and no germline BRCA1/2 mutations (gBRCA1/2mut).

METHODS

NOBROLA (NCT03367689) is a single-arm, open-label, multicenter, phase IIa trial, enrolling adult patients with advanced TNBC without gBRCA1/2mut and with HRD, who were treated with olaparib. The primary endpoint was clinical benefit rate (CBR) per RECIST v.1.1.

RESULTS

Six of 114 patients were eligible and received olaparib. Median follow up was 8.5 months. CBR and overall response rate (ORR) were 50 % (95 % CI, 11.8-88.2).

CONCLUSIONS

The observed results could prompt further investigation.

TRIAL

ClinicalTrials.gov identifier NCT03367689.

Clinicopathological Features and Oncological Outcomes of Germline Partner and Localizer of Breast Cancer 2-Mutated Breast Cancer in Korea

PURPOSE

The partner and localizer of breast cancer 2 (PALB2) mutation is a predisposition to breast cancer development. However, limited clinical data are available for the Korean population. Therefore, this study aimed to compare the characteristics and oncological outcomes of patients with PALB2-mutated and non-mutated PALB2 in Korea.

METHODS

A total of 1,463 breast cancer (BRCA) 1/2 mutation-negative breast cancer underwent comprehensive multigene sequencing between 2016 and 2019 at Severance Hospital, Seoul, Korea. Clinicopathological data and oncological results of PALB2 mutated patients were prospectively collected and compared with those of the non-mutated group.

RESULTS

PALB2 mutations were identified in 1.2% (17/1,463) of the patients. The median age at diagnosis was 46 (30-73) years, and the median tumor size was 1.8 (0.05-3.5) cm. All patients with PALB2 mutations had histologic grades II-III, and a triple-negative subtype was found in 23.5% (4/17); however, there were no significant differences in clinicopathological data between the groups. During the median follow-up time of 38.5 months, locoregional recurrence occurred in 4.2% (44/1,043), distant recurrence was reported in 3.0% (31/1,043), and contralateral breast cancer was diagnosed in 0.8% (9/1,043) of patients, with no significant difference observed between the groups. All-cause mortality was observed in 1.8% (19/1,028) of the non-mutated group and none in the PALB2 mutation group. However, survival analyses demonstrated no significant differences in all-cause mortality (p = 0.524) and recurrence-free survival (p = 0.319).

CONCLUSION

Clinicopathological features and oncological outcomes of PALB2 mutated breast cancer were not significantly different from those of non-mutated breast cancer in the Korean population.

Navigating Treatment Pathways in Metastatic Hormone Receptor-Positive, HER2-Negative Breast Cancer: Optimizing Second-Line Endocrine and Targeted Therapies

The Oncology Grand Rounds series is designed to place original reports published in the Journal into clinical context. A case presentation is followed by a description of diagnostic and management challenges, a review of the relevant literature, and a summary of the authors' suggested management approaches. The goal of this series is to help readers better understand how to apply the results of key studies, including those published in Journal of Clinical Oncology, to patients seen in their own clinical practice.

Comprehensive Clinical Genetics, Molecular and Pathological Evaluation Efficiently Assist Diagnostics and Therapy Selection in Breast Cancer Patients with Hereditary Genetic Background

Using multigene panel testing for the diagnostic evaluation of patients with hereditary breast and ovarian cancer (HBOC) syndrome often identifies clinically actionable variants in genes with varying levels of penetrance. High-penetrance genes (BRCA1, BRCA2, CDH1, PALB2, PTEN, STK11, TP53) inform specific clinical surveillance and therapeutic decisions, while recommendations for moderate-penetrance genes (ATM, BARD1, BRIP1, CHEK2, MLH1, MSH2, MSH6, PMS2, EPCAM, NF1, RAD51C, RAD51D) are more limited. A detailed disease history, including pedigree data, helps formulate the most appropriate and personalised management strategies. In this study, we evaluated the clinical benefits of comprehensive hereditary cancer gene panel testing and a pre-sent questionnaire in Hungarian patients with suspected HBOC syndrome. We prospectively enrolled 513 patients referred for HBOC testing. Of these, 463 met the genetic testing criteria, while 50 did not but were tested due to potential therapeutic indications. Additionally, a retrospective cohort of 47 patients who met the testing criteria but had previously only been tested for BRCA1/2 was also analysed. Among the 463 patients in the prospective cohort, 96 (20.7%) harboured pathogenic/likely pathogenic (P/LP) variants-67 in high-penetrance genes and 29 in moderate-penetrance genes. This ratio was similar in the retrospective cohort (6/47; 12.7%). In patients who did not meet the testing criteria, no mutations in high-penetrance genes were found, and only 3 of 50 (6%) harboured P/LP variants in moderate-penetrance genes. Secondary findings (P/LP variants in non-HBOC-associated genes) were identified in two patients. In the prospective cohort, P/LP variants in BRCA1 and BRCA2 were the most prevalent (56/96; 58.3%), and the extended testing doubled the P/LP detection ratio. Among moderate-penetrance genes, five cases (three in the prospective and two in the retrospective cohorts) had P/LP variants in Lynch syndrome-associated genes. Further immunohistochemistry analysis of breast tumour tissues helped clarify the causative role of these variants. Comprehensive clinical and molecular genetic evaluation is beneficial for the diagnosis and management of patients with P/LP variants in hereditary tumour-predisposing genes and can serve as a basis for effective therapy selection, such as PARP inhibitors or immunotherapy.

Germline Variant Spectrum in Southern Italian High-Risk Hereditary Breast Cancer Patients: Insights from Multi-Gene Panel Testing

Hereditary breast cancer accounts for 5-10% of all cases, with pathogenic variants in BRCA1/2 and other susceptibility genes playing a crucial role. This study elucidates the prevalence and spectrum of germline variants in 13 cancer predisposition genes among high-risk hereditary breast cancer patients from Southern Italy. We employed next-generation sequencing (NGS) to analyze 254 individuals selected through genetic counseling. Pathogenic or likely pathogenic variants were identified in 13% (34/254) of patients, with 54% of these variants occurring in non-BRCA1/2 genes. Notably, we observed a recurrent BRCA1 c.4964_4982del founder mutation, underscoring the importance of population-specific genetic screening. The spectrum of variants extended beyond BRCA1/2 to include PALB2, ATM, TP53, CHEK2, and RAD51C, highlighting the genetic heterogeneity of breast cancer susceptibility. Variants of uncertain significance were detected in 20% of patients, emphasizing the ongoing challenge of variant interpretation in the era of multi-gene panel testing. These findings not only enhance our understanding of the genetic landscape of breast cancer in Southern Italy but also provide a foundation for developing more targeted, population-specific approaches to genetic testing and counseling, ultimately contributing to the advancement of precision medicine in oncology.

An interpretable artificial intelligence framework for designing synthetic lethality-based anti-cancer combination therapies

INTRODUCTION

Synthetic lethality (SL) provides an opportunity to leverage different genetic interactions when designing synergistic combination therapies. To further explore SL-based combination therapies for cancer treatment, it is important to identify and mechanistically characterize more SL interactions. Artificial intelligence (AI) methods have recently been proposed for SL prediction, but the results of these models are often not interpretable such that deriving the underlying mechanism can be challenging.

OBJECTIVES

This study aims to develop an interpretable AI framework for SL prediction and subsequently utilize it to design SL-based synergistic combination therapies.

METHODS

We propose a knowledge and data dual-driven AI framework for SL prediction (KDDSL). Specifically, we use gene knowledge related to the SL mechanism to guide the construction of the model and develop a method to identify the most relevant gene knowledge for the predicted results.

RESULTS

Experimental and literature-based validation confirmed a good balance between predictive and interpretable ability when using KDDSL. Moreover, we demonstrated that KDDSL could help to discover promising drug combinations and clarify associated biological processes, such as the combination of MDM2 and CDK9 inhibitors, which exhibited significant anti-cancer effects in vitro and in vivo.

CONCLUSION

These data underscore the potential of KDDSL to guide SL-based combination therapy design. There is a need for biomedicine-focused AI strategies to combine rational biological knowledge with developed models.

BRCA-mutated breast cancer: the unmet need, challenges and therapeutic benefits of genetic testing

Mutations in the BRCA1 and/or BRCA2 genes (BRCAm) increase the risk of developing breast cancer (BC) and are found in ~5% of unselected patients with the disease. BC resulting from a germline BRCAm (gBRCAm) has distinct clinical characteristics along with increased sensitivity to DNA-damaging agents such as poly(ADP-ribose) polymerase (PARP) inhibitors and platinum-based chemotherapies, and potentially decreased sensitivity to cyclin-dependent kinase 4 and 6 (CDK4/6) inhibitors. Given the evolving treatment landscape for gBRCAm BC in early and advanced disease settings, timely determination of gBRCAm status is fundamental to facilitate the most effective treatment strategy for patients. However, many patients with gBRCAm are not identified due to suboptimal referral rates and/or a low uptake of genetic testing. We discuss current evidence for a differential response to treatment in patients with gBRCAm in early and advanced BC settings, including outcomes with PARP inhibitors, platinum-based chemotherapies, and CDK4/6 inhibitors, as well as ongoing treatment innovations and the potential of these treatment approaches. Current genetic testing strategies are also examined, including the latest guidelines on who and when to test for gBRCAm, as well as challenges to testing and how these may be overcome.

PARP Inhibitors in Pancreatic Cancer with Homologous Recombination Repair Gene Mutations: A Single-Institution Experience

BACKGROUND

Limited data are available regarding the anticancer activity of PARP inhibitors (PARPis) in pancreatic cancer with mutations in HRR genes other than BRCA and PALB2.

METHODS

We retrospectively reviewed the clinical characteristics and outcomes of 48 patients with advanced pancreatic cancer harboring pathogenic germline and/or somatic HRR mutations who were treated with PARPis.

RESULTS

Thirty patients had germline (g)HRR mutations only, twelve had somatic (s)HRR mutations only, and six had concomitant gHRR and sHRR mutations. The objective response rate (ORR) was 22%. The median progression-free survival (mPFS) and overall survival (mOS) were 6.9 and 11.5 months, respectively. Five patients received olaparib in the front-line setting due to borderline performance status. Their ORR was 20%, and their mPFS and mOS were both 11.3 months. The ORR was higher in patients with BRCA or PALB2 mutations (germline or somatic) than in those with non-BRCA/PALB2 mutations. Patients with somatic non-BRCA/PALB2 variants had a shorter mPFS. Patients with concomitant gHRR/sHRR mutations or gHRR mutations alone had a significantly longer mPFS than those with sHRR mutations only.

CONCLUSIONS

PARP inhibitors may be considered for patients with advanced pancreatic cancer harboring pathogenic alterations of BRCA who cannot tolerate standard chemotherapy. Maintenance PARPis can be considered in selected patients with non-BRCA/non-PALB2 HRR mutations.

Poly (ADP-ribose) Polymerase Inhibitor Resistance Driven by Emergence of Polyclonal Mutations With Convergent Evolution: A Molecular Tumor Board Discussion

Polyclonal convergent evolution to PARPi resistance in a patient with metastatic breast cancer with gPALB2.

DNA damage response in breast cancer and its significant role in guiding novel precise therapies

DNA damage response (DDR) deficiency has been one of the emerging targets in treating breast cancer in recent years. On the one hand, DDR coordinates cell cycle and signal transduction, whose dysfunction may lead to cell apoptosis, genomic instability, and tumor development. Conversely, DDR deficiency is an intrinsic feature of tumors that underlies their response to treatments that inflict DNA damage. In this review, we systematically explore various mechanisms of DDR, the rationale and research advances in DDR-targeted drugs in breast cancer, and discuss the challenges in its clinical applications. Notably, poly (ADP-ribose) polymerase (PARP) inhibitors have demonstrated favorable efficacy and safety in breast cancer with high homogenous recombination deficiency (HRD) status in a series of clinical trials. Moreover, several studies on novel DDR-related molecules are actively exploring to target tumors that become resistant to PARP inhibition. Before further clinical application of new regimens or drugs, novel and standardized biomarkers are needed to develop for accurately characterizing the benefit population and predicting efficacy. Despite the promising efficacy of DDR-related treatments, challenges of off-target toxicity and drug resistance need to be addressed. Strategies to overcome drug resistance await further exploration on DDR mechanisms, and combined targeted drugs or immunotherapy will hopefully provide more precise or combined strategies and expand potential responsive populations.

BRCA genetic testing and counseling in breast cancer: how do we meet our patients' needs?

BRCA1 and BRCA2 are tumor suppressor genes that have been linked to inherited susceptibility of breast cancer. Germline BRCA1/2 pathogenic or likely pathogenic variants (gBRCAm) are clinically relevant for treatment selection in breast cancer because they confer sensitivity to poly(ADP-ribose) polymerase (PARP) inhibitors. BRCA1/2 mutation status may also impact decisions on other systemic therapies, risk-reducing measures, and choice of surgery. Consequently, demand for gBRCAm testing has increased. Several barriers to genetic testing exist, including limited access to testing facilities, trained counselors, and psychosocial support, as well as the financial burden of testing. Here, we describe current implications of gBRCAm testing for patients with breast cancer, summarize current approaches to gBRCAm testing, provide potential solutions to support wider adoption of mainstreaming testing practices, and consider future directions of testing.

Prevention, diagnosis and clinical management of hereditary breast cancer beyond BRCA1/2 genes

The detection of germline pathogenic variants (gPVs) in BRCA1/2 and other breast cancer (BC) genes is rising exponentially thanks to the advent of multi-gene panel testing. This promising technology, coupled with the availability of specific therapies for BC BRCA-related, has increased the number of patients eligible for genetic testing. Implementing multi-gene panel testing for hereditary BC screening holds promise to maximise benefits for patients at hereditary risk of BC. These benefits range from prevention programs to antineoplastic-targeted therapies. However, the clinical management of these patients is complex and requires guidelines based on recent evidence. Furthermore, applying multi-gene panel testing into clinical practice increases the detection of variants of uncertain significance (VUSs). This augments the complexity of patients' clinical management, becoming an unmet need for medical oncologists. This review aims to collect updated evidence on the most common BC-related genes besides BRCA1/2, from their biological role in BC development to their potential impact in tailoring prevention and treatment strategies.

Deleterious alterations in homologous recombination repair genes and efficacy of platinum-based chemotherapy in biliary tract cancers

BACKGROUND

Platinum-based chemotherapy represents the standard first-line treatment for biliary tract cancers (BTC). Deficits in genes involved in the homologous recombination (HR) and DNA damage response (DDR) may confer higher sensitivity to platinum agents.

METHODS

We retrospectively included patients affected by BTC from 2 Italian institutions. Inclusion criteria consist of the receipt of platinum-based chemotherapy in the metastatic setting and the availability of comprehensive genomic profiling using next-generation sequencing (NGS). Patients were included in the HRD-like group if demonstrated oncogenic or likely oncogenic alterations in HR-/DDR-genes. Clinical endpoints were compared between the HRD-like group and the non-HRD-like group.

RESULTS

Seventy-four patients were included, of whom 25 (33%) in the HRD-like group and 49 (66%) in the non-HRD group. With a median follow-up of 26.04 months (interquartile-range [IQR] 9.41-29.27) in the HRD-like group and of 22.48 months (IQR 16.86-40.53) in the non-HRD group, no PFS difference emerged, with a mPFS of 5.18 months in the HRD-like group compared to 6.04 months in the non-HRD group (hazard ratio [HR], 1.017, 95% CI 0.58-1.78; P = .95). No differences were observed in DCR (64% [95 CI 45%-83%] vs 73% [95 CI 61%-86%]; P = .4), and CBR (45% [95% CI 28%-73%] vs 50% [95% CI, 37%-68%]; P = .9) between the HRD-like group and non-HRD groups, respectively. Median OS did not statistically differ between the HRD-like group and non-HRD group (26.7 vs 18.0 months, respectively; HR, 0.670, 0.33 to 1.37, P = .27).

CONCLUSION

HR-/DDR-genes, when assessed with regular tumor-only NGS panels, provide limited clinical validity to identify patients with BTC more likely to benefit from platinum-based chemotherapy.

6th and 7th International consensus guidelines for the management of advanced breast cancer (ABC guidelines 6 and 7)

This manuscript describes the Advanced Breast Cancer (ABC) international consensus guidelines updated at the last two ABC international consensus conferences (ABC 6 in 2021, virtual, and ABC 7 in 2023, in Lisbon, Portugal), organized by the ABC Global Alliance. It provides the main recommendations on how to best manage patients with advanced breast cancer (inoperable locally advanced or metastatic), of all breast cancer subtypes, as well as palliative and supportive care. These guidelines are based on available evidence or on expert opinion when a higher level of evidence is lacking. Each guideline is accompanied by the level of evidence (LoE), grade of recommendation (GoR) and percentage of consensus reached at the consensus conferences. Updated diagnostic and treatment algorithms are also provided. The guidelines represent the best management options for patients living with ABC globally, assuming accessibility to all available therapies. Their adaptation (i.e. resource-stratified guidelines) is often needed in settings where access to care is limited.

Germline Genetic Testing for Hereditary Breast and Ovarian Cancer: Current Concepts in Risk Evaluation

Our understanding of hereditary breast and ovarian cancer has significantly improved over the past two decades. In addition to BRCA1/2, pathogenic variants in several other DNA-repair genes have been shown to increase the risks of breast and ovarian cancer. The magnitude of cancer risk is impacted not only by the gene involved, but also by family history of cancer, polygenic risk scores, and, in certain genes, pathogenic variant type or location. While estimates of breast and ovarian cancer risk associated with pathogenic variants are available, these are predominantly based on studies of high-risk populations with young age at diagnosis of cancer, multiple primary cancers, or family history of cancer. More recently, breast cancer risk for germline pathogenic variant carriers has been estimated from population-based studies. Here, we provide a review of the field of germline genetic testing and risk evaluation for hereditary breast and ovarian cancers in high-risk and population-based settings.

Screening and Testing for Homologous Recombination Repair Deficiency (HRD) in Breast Cancer: an Overview of the Current Global Landscape

PURPOSE OF REVIEW

Homologous recombination repair deficiency (HRD) increases breast cancer susceptibility and influences both prophylactic and active management of breast cancer. This review evaluates HRD testing and the therapeutic implications of HRD in a global context.

RECENT FINDINGS

Ongoing research efforts have highlighted the importance of HRD beyond BRCA1/2 as a potential therapeutic target in breast cancer. However, despite the improved affordability of next-generation sequencing (NGS) and the discovery of PARP inhibitors, economic and geographical barriers in access to HRD testing and breast cancer screening do not allow all patients to benefit from the personalized treatment approach they provide. Advancements in HRD testing modalities and targeted therapeutics enable tailored breast cancer management. However, inequalities in access to testing and optimized treatments are contributing to widening health disparities globally.