Antibody-drug conjugates in lung and breast cancer: Current evidence and future directions - a position statement from the ETOP IBCSG Partners Foundation

Following the approval of the first antibody-drug conjugates (ADCs) in the early 2000s, development has increased dramatically, with 14 ADCs now approved and >100 in clinical development. In lung cancer, trastuzumab deruxtecan (T-DXd) is approved in human epidermal growth factor receptor 2 (HER2)-mutated, unresectable or metastatic non-small cell lung cancer, with ADCs targeting HER3 (patritumab deruxtecan), trophoblast cell-surface antigen 2 (datopotamab deruxtecan and sacituzumab govitecan [SG]) and mesenchymal-epithelial transition factor (telisotuzumab vedotin) in late-stage clinical development. In breast cancer, several agents are already approved and widely used, including trastuzumab emtansine, T-DXd and SG, and multiple late-stage trials are ongoing. Thus, in the coming years, we are likely to see significant changes to treatment algorithms. As the number of available ADCs increases, biomarkers (of response and resistance) to better select patients are urgently needed. Biopsy sample collection at the time of treatment selection and incorporation of translational research into clinical trial designs are therefore critical. Biopsy samples taken peri- and post-ADC treatment combined with functional genomics screens could provide insights into response/resistance mechanisms as well as the impact of ADCs on tumour biology and the tumour microenvironment, which could improve understanding of the mechanisms underlying these complex molecules. Many ADCs are undergoing evaluation as combination therapy, but a high bar should be set to progress clinical evaluation of any ADC-based combination, particularly considering the high cost and potential toxicity implications. Efforts to optimise ADC dosing/duration, sequencing and the potential for ADC rechallenge are also important, especially considering sustainability aspects. The ETOP IBCSG Partners Foundation are driving strong collaborations in this field and promoting the generation/sharing of databases, repositories and registries to enable greater access data. This will allow the most important research questions to be identified and prioritised, which will ultimately accelerate progress and help to improve patient outcomes.

Multiplexed high-throughput immune cell imaging in patients with high-risk triple negative early breast cancer: Analysis from the International Breast Cancer Study Group (IBCSG) Trial 22-00

BACKGROUND

Triple-negative breast cancer (TNBC) is the most aggressive breast cancer (BC) subtype, with dismal prognosis and limited option in advanced settings, yet stromal tumor infiltrating lymphocytes (sTILs) in this subtype has a predictive role.

PATIENTS AND METHODS

The International Breast Cancer Study Group (IBCSG) Trial 22-00 is a randomized phase III clinical trial testing the efficacy of low-dose metronomic oral Cyclophosphamide-Methotrexate (CM) maintenance following standard adjuvant chemotherapy treatment for early-stage hormone receptor-negative breast cancer patients. A case-cohort sampling was used. We characterized immune cells infiltrates in patients with TNBC by 6 plex immunofluorescence (IF) staining for CD4, FOXP3, CD3, cytokeratine and CD8 RESULTS: We confirmed that high immune CD3+ T cells as well as stromal and intra-epithelial Tregs (CD4+Foxp3+ T cells) infiltrates were associated with a better Distant Recurrence-Free Interval (DRFI), especially in LN+ patient, regardless of the treatment. More importantly, we showed that the spatial distribution of immune cells at baseline is crucial, as CM maintenance was detrimental for T cells excluded LN+ TNBC patients.

CONCLUSIONS

immune spatial classification on immune cells infiltrates seems crucial and could help patients' selection in clinical trial and greatly improve responses to specific therapies.

Neratinib + fulvestrant + trastuzumab for HR-positive, HER2-negative, HER2-mutant metastatic breast cancer: outcomes and biomarker analysis from the SUMMIT trial

BACKGROUND

HER2 mutations are targetable alterations in patients with hormone receptor-positive (HR+) metastatic breast cancer (MBC). In the SUMMIT basket study, patients with HER2-mutant MBC received neratinib monotherapy, neratinib + fulvestrant, or neratinib + fulvestrant + trastuzumab (N + F + T). We report results from 71 patients with HR+, HER2-mutant MBC, including 21 (seven in each arm) from a randomized substudy of fulvestrant versus fulvestrant + trastuzumab (F + T) versus N + F + T.

PATIENTS AND METHODS

Patients with HR+ HER2-negative MBC with activating HER2 mutation(s) and prior cyclin-dependent kinase 4/6 inhibitor (CDK4/6i) therapy received N + F + T (oral neratinib 240 mg/day with loperamide prophylaxis, intramuscular fulvestrant 500 mg on days 1, 15, and 29 of cycle 1 then q4w, intravenous trastuzumab 8 mg/kg then 6 mg/kg q3w) or F + T or fulvestrant alone. Those whose disease progressed on F + T or fulvestrant could cross-over to N + F + T. Efficacy endpoints included investigator-assessed objective response rate (ORR), clinical benefit rate (RECIST v1.1), duration of response, and progression-free survival (PFS). Plasma and/or formalin-fixed paraffin-embedded tissue samples were collected at baseline; plasma was collected during and at end of treatment. Extracted DNA was analyzed by next-generation sequencing.

RESULTS

ORR for 57 N + F + T-treated patients was 39% [95% confidence interval (CI) 26% to 52%); median PFS was 8.3 months (95% CI 6.0-15.1 months). No responses occurred in fulvestrant- or F + T-treated patients; responses in patients crossing over to N + F + T supported the requirement for neratinib in the triplet. Responses were observed in patients with ductal and lobular histology, 1 or ≥1 HER2 mutations, and co-occurring HER3 mutations. Longitudinal circulating tumor DNA sequencing revealed acquisition of additional HER2 alterations, and mutations in genes including PIK3CA, enabling further precision targeting and possible re-response.

CONCLUSIONS

The benefit of N + F + T for HR+ HER2-mutant MBC after progression on CDK4/6is is clinically meaningful and, based on this study, N + F + T has been included in the National Comprehensive Cancer Network treatment guidelines. SUMMIT has improved our understanding of the translational implications of targeting HER2 mutations with neratinib-based therapy.

Genomic characterisation of hormone receptor-positive breast cancer arising in very young women

BACKGROUND

Very young premenopausal women diagnosed with hormone receptor-positive, human epidermal growth factor receptor 2-negative (HR+HER2-) early breast cancer (EBC) have higher rates of recurrence and death for reasons that remain largely unexplained.

PATIENTS AND METHODS

Genomic sequencing was applied to HR+HER2- tumours from patients enrolled in the Suppression of Ovarian Function Trial (SOFT) to determine genomic drivers that are enriched in young premenopausal women. Genomic alterations were characterised using next-generation sequencing from a subset of 1276 patients (deep targeted sequencing, n = 1258; whole-exome sequencing in a young-age, case-control subsample, n = 82). We defined copy number (CN) subgroups and assessed for features suggestive of homologous recombination deficiency (HRD). Genomic alteration frequencies were compared between young premenopausal women (<40 years) and older premenopausal women (≥40 years), and assessed for associations with distant recurrence-free interval (DRFI) and overall survival (OS).

RESULTS

Younger women (<40 years, n = 359) compared with older women (≥40 years, n = 917) had significantly higher frequencies of mutations in GATA3 (19% versus 16%) and CN amplifications (CNAs) (47% versus 26%), but significantly lower frequencies of mutations in PIK3CA (32% versus 47%), CDH1 (3% versus 9%), and MAP3K1 (7% versus 12%). Additionally, they had significantly higher frequencies of features suggestive of HRD (27% versus 21%) and a higher proportion of PIK3CA mutations with concurrent CNAs (23% versus 11%). Genomic features suggestive of HRD, PIK3CA mutations with CNAs, and CNAs were associated with significantly worse DRFI and OS compared with those without these features. These poor prognostic features were enriched in younger patients: present in 72% of patients aged <35 years, 54% aged 35-39 years, and 40% aged ≥40 years. Poor prognostic features [n = 584 (46%)] versus none [n = 692 (54%)] had an 8-year DRFI of 84% versus 94% and OS of 88% versus 96%. Younger women (<40 years) had the poorest outcomes: 8-year DRFI 74% versus 85% and OS 80% versus 93%, respectively.

CONCLUSION

These results provide insights into genomic alterations that are enriched in young women with HR+HER2- EBC, provide rationale for genomic subgrouping, and highlight priority molecular targets for future clinical trials.

Discovery of a novel, highly potent and orally bioavailable pyrrolidinone indole series of irreversible Myeloperoxidase (MPO) inhibitors

Myeloperoxidase (MPO) is a heme-containing peroxidase from phagocytic cells, which plays an important role in the innate immune response. The primary anti-microbial function of MPO is achieved by catalyzing the oxidation of halides by hydrogen peroxide (H₂O₂). Upon activation of phagocytes, MPO activity is detectable in both phagosomes and extracellularly, where it can remain or transcytose into interstitial compartments. Activated MPO leads to oxidative stress and tissue damage in many inflammatory states, including cardiovascular disease. Starting from a low molecular weight (LMW) high throughput screening (HTS) hit, here we report the discovery of a novel pyrrolidinone indole (IN-4) as a highly potent MPO inhibitor. This compound displays similar in vitro potency across peroxidation, plasma and NETosis assays. In a dilution/dialysis study, <5% of the original MPO activity was detected post-incubation of MPO with IN-4, suggesting irreversible enzyme inhibition. A fast MPO inactivation rate (k_inact/K_i) and low partition ratio (k₃/k₄) make IN-4 kinetic properties attractive for an MPO inhibitor. This compound also displays significant selectivity over the closely related thyroid peroxidase (TPO), and is selective for extracellular MPO over intracellular (neutrophil) MPO. Moreover, IN-4 shows good exposure, low clearance and high oral bioavailability in mice, rats and dogs. The high in vitro MPO activity and high oral exposure observed with IN-4 result in a dose-dependent inhibition of MPO activity in three mouse models of inflammation. In conclusion, IN-4 is a novel, potent, mechanism-based and selective MPO inhibitor, which may be used as superior therapeutic agent to treat multiple inflammatory conditions, including cardiovascular disease.

Preclinical Characterization of Vadadustat (AKB-6548), an Oral Small Molecule Hypoxia-Inducible Factor Prolyl-4-Hydroxylase Inhibitor, for the Potential Treatment of Renal Anemia

Pharmacological inhibition of prolyl-4-hydroxylase domain (PHD) enzymes stabilizes hypoxia-inducible factors (HIFs), transcription factors that activate target genes that, among others, increase erythropoietin (EPO) synthesis, resulting in the production of new red blood cells (RBCs). Herein, we summarize the preclinical characteristics of the small molecule HIF prolyl-4-hydroxylase inhibitor vadadustat (AKB-6548), which is in development for the treatment of anemia in patients with chronic kidney disease (CKD). Vadadustat inhibits the enzyme activity of all three human PHD isozymes, PHD1, PHD2, and PHD3, with similar low nanomolar inhibitory constant values. PHD enzyme inhibition by vadadustat is competitive with endogenous cofactor 2-oxoglutarate and is insensitive to free iron concentration. In the human hepatocellular carcinoma cell line (Hep 3B) and human umbilical vein endothelial cells, PHD inhibition by vadadustat leads to the time- and concentration-dependent stabilization of HIF-1α and HIF-2α In Hep 3B cells, this in turn results in the synthesis and secretion of EPO; vascular endothelial growth factor is not measured at detectable levels. A single oral dose of vadadustat in rats potently increases circulating levels of EPO, and daily oral dosing for 14 days increases RBC indices in healthy rats and in the 5/6 nephrectomy model of CKD. In mice and dogs, once-daily repeat oral dosing increases hemoglobin and hematocrit. Vadadustat has a relatively short half-life in all nonclinical species evaluated and does not accumulate when administered as a single bolus dose (oral or intravenous) or upon repeat oral dosing. The pharmacological profile of vadadustat supports continued development for treatment of renal anemia. SIGNIFICANCE STATEMENT: Vadadustat (AKB-6548) is an orally bioavailable small molecule prolyl-4-hydroxylase inhibitor in development for anemia of chronic kidney disease. It is an equipotent inhibitor of the three human prolyl-4-hydroxylase domain isoforms, which activates erythropoiesis through stabilization of hypoxia-inducible factor (HIF)-1α and HIF-2α, increasing production of erythropoietin, without detectable stimulation of vascular endothelial growth factor.

Abstract ES6-3: Immunotherapy vs Capecitabine for Triple Negative Breast Cancer

Immunotherapy vs capecitabine for triple negative breast cancer. Educational session. Sherene Loi, MD, PhDPeter MacCallum Cancer Centre, Melbourne, Australia. Neoadjuvant treatment is now standard of care for the majority of early stage triple negative breast cancer (TNBC), with the achievement of non-pathological complete response (pCR) the main indicator to escalate treatment. Until recently only capecitabine was used in this setting. 2021 has seen reporting of the OlympiA adjuvant study, which reports major benefits for olaparib in germline BRCA positive TNBC patients, though a minority. KEYNOTE522 has now set the scene for incorporating neoadjuvant pembrolizumab with chemotherapy in early stage TNBC, with significantly improved event free survival, particularly those that do not achieve pCR. In this talk I will examine how we can rationally think about treating these patients with the available options.

Citation Format: S Loi. Immunotherapy vs Capecitabine for Triple Negative Breast Cancer [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr ES6-3.

Continuous versus intermittent extended adjuvant letrozole for breast cancer: final results of randomized phase III SOLE (Study of Letrozole Extension) and SOLE Estrogen Substudy

BACKGROUND

Late recurrences in postmenopausal women with hormone receptor-positive breast cancers remain an important challenge. Avoidance or delayed development of resistance represents the main objective in extended endocrine therapy (ET). In animal models, resistance was reversed with restoration of circulating estrogen levels during interruption of letrozole treatment. This phase III, randomized, open-label Study of Letrozole Extension (SOLE) studied the effect of extended intermittent letrozole treatment in comparison with continuous letrozole. In parallel, the SOLE estrogen substudy (SOLE-EST) analyzed the levels of estrogen during the interruption of treatment.

PATIENTS AND METHODS

SOLE enrolled 4884 postmenopausal women with hormone receptor-positive, lymph node-positive, operable breast cancer between December 2007 and October 2012 and among them, 104 patients were enrolled in SOLE-EST. They must have undergone local treatment and have completed 4-6 years of adjuvant ET. Patients were randomized between continuous letrozole (2.5 mg/day orally for 5 years) and intermittent letrozole treatment (2.5 mg/day for 9 months followed by a 3-month interruption in years 1-4 and then 2.5 mg/day during all of year 5).

RESULTS

Intention-to-treat population included 4851 women in SOLE (n = 2425 in the intermittent and n = 2426 in the continuous letrozole groups) and 103 women in SOLE-EST (n = 78 in the intermittent and n = 25 in the continuous letrozole groups). After a median follow-up of 84 months, 7-year disease-free survival (DFS) was 81.4% in the intermittent group and 81.5% in the continuous group (hazard ratio: 1.03, 95% confidence interval: 0.91-1.17). Reported adverse events were similar in both groups. Circulating estrogen recovery was demonstrated within 6 weeks after the stop of letrozole treatment.

CONCLUSIONS

Extended adjuvant ET by intermittent administration of letrozole did not improve DFS compared with continuous use, despite the recovery of circulating estrogen levels. The similar DFS coupled with previously reported quality-of-life advantages suggest intermittent extended treatment is a valid option for patients who require or prefer a treatment interruption.

The journey of tumor-infiltrating lymphocytes as a biomarker in breast cancer: clinical utility in an era of checkpoint inhibition

In 2014, we described a method to quantify percentage of tumor-infiltrating lymphocytes (TILs) on hematoxylin and eosin-stained slides of breast cancer samples using light microscopy that could be performed easily by pathologists with no extra stains. The aim of detailing the method was to facilitate independent research groups replicating our prognostic findings using TIL quantity in early-stage breast cancers. A global working group of breast pathologists was convened to standardize, test reproducibility, and refine the method. A website was also established which allowed free training (www.tilsinbreastcancer.org). As a result of this work, TIL data have been collected in over 20 000 primary breast cancer samples worldwide and the robust associations with better prognoses in triple-negative breast cancer (TNBC) and HER2+ BC have been confirmed. This has resulted in the inclusion of the TIL biomarker in several international breast cancer guidelines as well as in national criteria for routine pathology reporting. TIL therefore represents the first biological prognostic biomarker for early-stage TNBCs, and here its prognostic effect is linear, with values of 30%-50% being suggested as suitable for use in potential chemotherapy de-escalation studies. The efficacy of immune checkpoint-targeted agents in breast cancer now provides direct evidence that host immune responses can modify tumor growth in some patients. With the recent granting of accelerated approvals for the first PD-1/PD-L1 targeting agents in early and advanced TNBC, our focus has now moved to investigating the clinical utility of TIL in the setting of immune checkpoint agents, with or without PD-L1 protein assessment. Emerging data suggest that TIL quantity can help clinicians identify patients with breast cancer who benefit most from PD-1/PD-L1 inhibition. In patients with advanced TNBC and HER2+ disease a TIL cut-off of 5% or 10%, with PD-L1 expression can define 'immune-enriched' tumors and currently seems to have the most clinical relevance in this context.

Abstract SP086: Rationale for combination therapies

There has been a lot of emerging clinical data in the treatment of early and late stage breast cancer with PD-1/PD-L1 inhibitors in the last 12 months. We have learnt several important points relevant for future development in breast cancer patients. Most important of these is the observation that early-stage disease has a different immune context to advanced disease. This is evidenced by study results that in the neoadjuvant settings PD-(L)1 inhibitors have efficacy in both PD-L1 positive and negative populations, whereas in the advanced setting, efficacy has only been reported in PD-L1 positive patients. It has been hypothesized that chemotherapy, or certain types of chemotherapy, may be more “immunogenic” than others, but thus far, there is scant evidence to support this. Rather it is more likely that the immune context is important. In the early-stage setting, many primary breast cancers (triple negative and HER2-positive) are highly infiltrated with immune cells, the cancers has received no prior treatment, and cancer burden is low, confined to the breast and ultimately completely removed. In contrast, in the advanced setting, the immune infiltrate is low to non-existent, patients often have higher disease burden, hostile tumor microenvironments in multiple organs sites, and have received prior treatment, implying that the cancer has evolved to become treatment resistant, as well as more efficient at suppressing or evading host immune detection. Hence, in the setting of recurrent disease, and likely also in the locally advanced setting, despite chemotherapy usage and objective tumor shrinkage, it is the pre-existing immunity that ultimately dictates the chances of benefit from PD-(L)1 inhibitors. What combinations are likely therefore to be effective in the advanced setting where immunity does not exist? Targeted therapies such as MEK and AKT inhibitors are being evaluated in clinical trials, thus far have proven disappointing. New antibody drug conjugates (ADCs) such as Sacituzumab Govetecan and DS-8201a have shown impressive anti-tumor activity in the advanced setting. However, given their proven cytotoxic bystander effects on nearby cells, it will be essential to evaluate ADCs and immunotherapy sequencing approaches to ensure that the scant amount of pre-existing local TIL is also not destroyed. Interestingly a recent study in advanced HER2-positive breast cancer (KATE2) reported benefit of atezolizumab to trastuzumab emantasine also in only PD-L1 positive patients. Notably T-DM1 does not have prominent bystander effects. Other possibilities to create immunity in the advanced setting include radiotherapy, more potent anti-HER2 agents, as well as genetically engineered T cell receptor or chimeric antigen receptor T cells, and agents targeting T regulatory cells. This task is likely to be a very challenging as it will require more than making “cold” tumors “hot”, as is probable that we will need to find the means that can re-invigorate the whole host immune system in the context of advanced breast cancer.

Citation Format: S Loi. Rationale for combination therapies [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr SP086.

Identifying oncogenic drivers associated with increased risk of late distant recurrence in postmenopausal, estrogen receptor-positive, HER2-negative early breast cancer: results from the BIG 1-98 study

BACKGROUND

In postmenopausal, estrogen receptor-positive, human epidermal growth factor receptor 2 (HER2)-negative early breast cancer, the risk for distant recurrence can extend beyond 5 years of adjuvant endocrine therapy. This study aims to identify genomic driver alterations associated with late distant recurrence.

PATIENTS AND METHODS

Next generation sequencing was used to characterize driver alterations in primary tumors from a subset of 764 postmenopausal estrogen receptor-positive/HER2-negative patients from the BIG 1-98 randomized trial. Late distant recurrence events were defined as ≥5 years from time of randomization). The association of driver alterations with distant recurrence-free interval in early and late time periods was assessed using Cox regression models. Multivariable analyses were carried out to adjust for clinicopathological factors. Weighted analysis methods were used in order to correct for over-sampling of distant recurrences.

RESULTS

A total of 538 of 764 (70%) samples were successfully sequenced including 88 (63%) early and 52 (37%) late distant recurrence events after a median follow up of 8.1 years. In univariable analysis for late distant recurrence, PIK3CA mutations (58.8%) were significantly associated with reduced risk [hazard ratio (HR) 0.40, 95% confidence interval (CI) 0.20-0.82, P = 0.012], whereas amplifications on chromosome 8p11 (10.9%) (HR 4.79, 95% CI 2.30-9.97, P < 0.001) and BRCA2 mutations (2.3%) (HR 5.39, 95% CI 1.51-19.29, P = 0.010) were significantly associated with an increased risk. In multivariable analysis, only amplifications on 8p11 (P = 0.002) and BRCA2 mutations (P = 0.013) remained significant predictors.

CONCLUSIONS

In estrogen receptor-positive/HER2-negative postmenopausal early breast cancer, PIK3CA mutations were associated with reduced risk of late distant recurrence, whereas amplifications on 8p11 and BRCA2 mutations were associated with increased risk of late distant recurrence. The characterization of oncogenic driver alterations may aid in refining treatment choices in the late disease setting, and help identify potential drug targets for testing in future trials.

Discovery of a novel indole pharmacophore for the irreversible inhibition of myeloperoxidase (MPO)

Myeloperoxidase (MPO) activity and subsequent generation of hypochlorous acid has been associated with the killing of host-invading microorganisms (e.g. bacteria, viruses, and fungi). However, during oxidative stress, high MPO activity can damage host tissue and is linked to several chronic inflammatory conditions. Herein, we describe the development of a novel biaryl, indole-pyrazole series of irreversible mechanism-based inhibitors of MPO. Derived from an indole-containing high-throughput screen hit, optimization efforts resulted in potent and selective 6-substituted indoles with good oral bioavailability and in vivo activity.

Pembrolizumab monotherapy for previously treated metastatic triple-negative breast cancer: cohort A of the phase II KEYNOTE-086 study

BACKGROUND

Treatment options for previously treated metastatic triple-negative breast cancer (mTNBC) are limited. In cohort A of the phase II KEYNOTE-086 study, we evaluated pembrolizumab as second or later line of treatment for patients with mTNBC.

PATIENTS AND METHODS

Eligible patients had centrally confirmed mTNBC, ≥1 systemic therapy for metastatic disease, prior treatment with anthracycline and taxane in any disease setting, and progression on or after the most recent therapy. Patients received pembrolizumab 200 mg intravenously every 3 weeks for up to 2 years. Primary end points were objective response rate in the total and PD-L1-positive populations, and safety. Secondary end points included duration of response, disease control rate (percentage of patients with complete or partial response or stable disease for ≥24 weeks), progression-free survival, and overall survival.

RESULTS

All enrolled patients (N = 170) were women, 61.8% had PD-L1-positive tumors, and 43.5% had received ≥3 previous lines of therapy for metastatic disease. ORR (95% CI) was 5.3% (2.7-9.9) in the total and 5.7% (2.4-12.2) in the PD-L1-positive populations. Disease control rate (95% CI) was 7.6% (4.4-12.7) and 9.5% (5.1-16.8), respectively. Median duration of response was not reached in the total (range, 1.2+-21.5+) and in the PD-L1-positive (range, 6.3-21.5+) populations. Median PFS was 2.0 months (95% CI, 1.9-2.0), and the 6-month rate was 14.9%. Median OS was 9.0 months (95% CI, 7.6-11.2), and the 6-month rate was 69.1%. Treatment-related adverse events occurred in 103 (60.6%) patients, including 22 (12.9%) with grade 3 or 4 AEs. There were no deaths due to AEs.

CONCLUSIONS

Pembrolizumab monotherapy demonstrated durable antitumor activity in a subset of patients with previously treated mTNBC and had a manageable safety profile.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov, NCT02447003.

Prognostic value of tumor-infiltrating lymphocytes in patients with early-stage triple-negative breast cancers (TNBC) who did not receive adjuvant chemotherapy

BACKGROUND

Although stromal tumor-infiltrating lymphocytes (sTILs) have been considered an important prognostic factor in early-stage triple-negative breast cancer (TNBC), there have been limited data on their prognostic value in the absence of adjuvant chemotherapy.

PATIENTS AND METHODS

A pooled analysis was carried out using four cohorts of TNBC patients not treated with chemotherapy. sTILs were evaluated in the most representative tumoral block of surgical specimens. Cox proportional hazards regression models were used for invasive disease-free survival (iDFS), distant disease-free survival (D-DFS), and overall survival (OS), fitting sTILs as a continuous variable adjusted for clinicopathologic factors.

RESULTS

We analyzed individual data of 476 patients from 4 centers diagnosed between 1989 and 2015. Their median age was 64 years. The median tumor size was 1.6 cm and 83% were node-negative. The median level of sTILs was 10% (Q1-Q3, 4%-30%). Higher grade was associated with higher sTILs (P < 10-3). During follow-up, 107 deaths, and 173 and 118 events for iDFS and D-DFS were observed, respectively. In the multivariable analysis, sTILs obtained an independent prognostic value for all end points (likelihood ratio χ2 = 7.14 for iDFS; P < 10-2; χ2 = 9.63 for D-DFS, P < 10-2; χ2 = 5.96 for OS, P = 0.015). Each 10% increment in sTILs corresponded to a hazard ratio of 0.90 [95% confidence interval (CI) 0.82 - 0.97] for iDFS, 0.86 (95% CI 0.77 - 0.95) for D-DFS, and 0.88 (95% CI 0.79 - 0.98) for OS, respectively. In patients with pathological stage I tumors with sTILs ≥30% (n = 74), 5-year iDFS was 91% (95% CI 84% to 96%), D-DFS was 97% (95% CI 93% to 100%), and OS was 98% (95% CI 95% to 100%).

CONCLUSION

sTILs add important prognostic information in systemically untreated early-stage TNBC patients. Notably, sTILs can identify a subset of stage I TNBC patients with an excellent prognosis without adjuvant chemotherapy.

Clinical significance of CD73 in triple-negative breast cancer: multiplex analysis of a phase III clinical trial

Background

CD73 is an ecto-enzyme that promotes tumor immune escape through the production of immunosuppressive extracellular adenosine in the tumor microenvironment. Several CD73 inhibitors and adenosine receptor antagonists are being evaluated in phase I clinical trials.

Patients and methods

Full-face sections from formalin-fixed paraffin-embedded primary breast tumors from 122 samples of triple-negative breast cancer (TNBC) from the BIG 02-98 adjuvant phase III clinical trial were included in our analysis. Using multiplex immunofluorescence and image analysis, we assessed CD73 protein expression on tumor cells, tumor-infiltrating leukocytes and stromal cells. We investigated the associations between CD73 protein expression with disease-free survival (DFS), overall survival (OS) and the extent of tumor immune infiltration.

Results

Our results demonstrated that high levels of CD73 expression on epithelial tumor cells were significantly associated with reduced DFS, OS and negatively correlated with tumor immune infiltration (Spearman's R= -0.50, P < 0.0001). Patients with high levels of CD73 and low levels of tumor-infiltrating leukocytes had the worse clinical outcome.

Conclusions

Taken together, our study provides further support that CD73 expression is associated with a poor prognosis and reduced anti-tumor immunity in human TNBC and that targeting CD73 could be a promising strategy to reprogram the tumor microenvironment in this BC subtype.