Investigator

Christine A.R. Lok

Gynecologic Oncologist · Netherlands Cancer Institute - Antoni van Leeuwenhoek Hospital, Gynecologic Oncology

CALChristine A.R. Lok
Papers(10)
Response to Systemic …Early Detection of Ov…Outcomes of patients …Evaluating the effect…Prognostic value of m…NOTCH Signaling Limit…Vulvar and vaginal ca…Real-world performanc…Practical Guidelines …Chemotherapy is not n…
Collaborators(10)
Jurgen M. J. PiekPien LofCornelis D. de KroonDaan van den BroekDaniel C. BruhmDennis J. SlamonDimitrios MathiosDuco H K GaillardE. Marielle HijmansEsther Lems
Institutions(8)
Ggd AmsterdamCatharina ZiekenhuisThe Netherlands Cance…Leiden UniversityJohns Hopkins Univers…University Of Califor…Oncode InstituteMaastricht University

Papers

Response to Systemic Therapies in Patient-Derived Cell Lines from Primary and Recurrent Adult Granulosa Cell Tumors

Abstract In patients with the rare adult-type granulosa cell tumor (aGCT), surgery is the primary treatment for both primary and recurrent disease. In cases of inoperable disease, systematic therapy is administered, but variable response rates and drug resistance complicate predicting the most effective therapy. Drug screen testing on patient-derived cell lines may offer a solution. In a national prospective study on aGCT, fresh tissue was cultured into 2D cell lines, testing 27 clinical and experimental drugs. Dose–response curves and synergy were calculated using GraphPad Prism and CompuSyn software. We established 34 patient-derived cell lines from tissue of 20 patients with aGCT. Of these, seven patients had a primary diagnosis of aGCT and 13 patients had recurrent disease. In eight patients, multiple tumor locations were cultured. On each cell line, 10 monotherapies and 17 combinations of drugs were tested. Carboplatin/gemcitabine showed efficacy and synergy in almost all patient-derived cell lines. Synergy could not be detected in the regular carboplatin/paclitaxel and carboplatin/etoposide combinations. Experimental combinations alpelisib/fulvestrant and alpelisib/gemcitabine showed efficacy of more than 75%. Drug screens on patient-derived tumor cell lines reflect the reality of the variable response of systemic therapy in patients with aGCT. In future research, this technique may be used to personalize the systemic treatment of patients with aGCT in a clinical study. The good response to carboplatin/gemcitabine in our patient-derived cell lines can then be confirmed in a clinical setting.

Early Detection of Ovarian Cancer Using Cell-Free DNA Fragmentomes and Protein Biomarkers

Abstract Ovarian cancer is a leading cause of death for women worldwide, in part due to ineffective screening methods. In this study, we used whole-genome cell-free DNA (cfDNA) fragmentome and protein biomarker [cancer antigen 125 (CA-125) and human epididymis protein 4 (HE4)] analyses to evaluate 591 women with ovarian cancer, with benign adnexal masses, or without ovarian lesions. Using a machine learning model with the combined features, we detected ovarian cancer with specificity >99% and sensitivities of 72%, 69%, 87%, and 100% for stages I to IV, respectively. At the same specificity, CA-125 alone detected 34%, 62%, 63%, and 100%, and HE4 alone detected 28%, 27%, 67%, and 100% of ovarian cancers for stages I to IV, respectively. Our approach differentiated benign masses from ovarian cancers with high accuracy (AUC = 0.88, 95% confidence interval, 0.83–0.92). These results were validated in an independent population. These findings show that integrated cfDNA fragmentome and protein analyses detect ovarian cancers with high performance, enabling a new accessible approach for noninvasive ovarian cancer screening and diagnostic evaluation. Significance: There is an unmet need for effective ovarian cancer screening and diagnostic approaches that enable earlier-stage cancer detection and increased overall survival. We have developed a high-performing accessible approach that evaluates cfDNA fragmentomes and protein biomarkers to detect ovarian cancer.

Outcomes of patients with early stage mucinous ovarian carcinoma: a Dutch population-based cohort study comparing expansile and infiltrative subtypes

This study aimed to assess the outcomes of patients with early stage mucinous ovarian carcinoma based on subtype (expansile vs infiltrative). We retrospectively analyzed all surgically treated patients with mucinous ovarian carcinoma in the Netherlands (2015-2020), using data from national registries. Subtypes were determined, with any ambiguities resolved by a dedicated gynecologic pathologist. Patients with International Federation of Gynecology and Obstetrics (FIGO) stage I were categorized into full staging, fertility-sparing, or partial stagings. Outcomes were overall survival and recurrence free survival, and recurrence rates. Among 409 identified patients, 257 (63%) had expansile and 152 (37%) had infiltrative tumors. Patients with expansile tumors had FIGO stage I more frequently (n=243, 95% vs n=116, 76%, p<0.001). For FIGO stage I disease, patients with expansile and infiltrative tumors underwent similar proportions of partial (n=165, 68% vs n=78, 67%), full (n=32, 13% vs n=23, 20%), and fertility-sparing stagings (n=46, 19% vs n=15, 13%) (p=0.139). Patients with expansile FIGO stage I received less adjuvant chemotherapy (n=11, 5% vs n=24, 21%, p<0.001), exhibited better overall and recurrence free survival (p=0.006, p=0.012), and fewer recurrences (n=13, 5% vs n=16, 14%, p=0.011). Survival and recurrence rates were similar across the expansile extent of staging groups. Patients undergoing fertility-sparing staging for infiltrative tumors had more recurrences compared with full or partial stagings, while recurrence free survival was similar across these groups. Full staging correlated with better overall survival in infiltrative FIGO stage I (p=0.022). While most patients with FIGO stage I underwent partial staging, those with expansile had better outcomes than those with infiltrative tumors. Full staging was associated with improved overall survival in infiltrative, but not in expansile FIGO stage I. These results provide insight for tailored surgical approaches.

Evaluating the effectiveness of pre-operative diagnosis of ovarian cancer using minimally invasive liquid biopsies by combining serum human epididymis protein 4 and cell-free DNA in patients with an ovarian mass

To assess the feasibility of scalable, objective, and minimally invasive liquid biopsy-derived biomarkers such as cell-free DNA copy number profiles, human epididymis protein 4 (HE4), and cancer antigen 125 (CA125) for pre-operative risk assessment of early-stage ovarian cancer in a clinically representative and diagnostically challenging population and to compare the performance of these biomarkers with the Risk of Malignancy Index (RMI). In this case-control study, we included 100 patients with an ovarian mass clinically suspected to be early-stage ovarian cancer. Of these 100 patients, 50 were confirmed to have a malignant mass (cases) and 50 had a benign mass (controls). Using WisecondorX, an algorithm used extensively in non-invasive prenatal testing, we calculated the benign-calibrated copy number profile abnormality score. This score represents how different a sample is from benign controls based on copy number profiles. We combined this score with HE4 serum concentration to separate cases and controls. Combining the benign-calibrated copy number profile abnormality score with HE4, we obtained a model with a significantly higher sensitivity (42% vs 0%; p<0.002) at 99% specificity as compared with the RMI that is currently employed in clinical practice. Investigating performance in subgroups, we observed especially large differences in the advanced stage and non-high-grade serous ovarian cancer groups. This study demonstrates that cell-free DNA can be successfully employed to perform pre-operative risk of malignancy assessment for ovarian masses; however, results warrant validation in a more extensive clinical study.

Prognostic value of molecular classification in stage IV endometrial cancer

Multiple studies have proven the prognostic value of molecular classification for stage I-III endometrial cancer patients. However, studies on the relevance of molecular classification for stage IV endometrial cancer patients are lacking. Hypothetically, poor prognostic molecular subtypes are more common in higher stages of endometrial cancer. Considering the poor prognosis of stage IV endometrial cancer patients, it is questionable whether molecular classification has additional prognostic value. Therefore, we determined which molecular subclasses are found in stage IV endometrial cancer and if there is a correlation with progression-free and overall survival. A retrospective multicenter cohort study was conducted using data from five Dutch hospitals. Patients with stage IV endometrial cancer at diagnosis who were treated with primary cytoreductive surgery or cytoreductive surgery after induction chemotherapy between January 2000 and December 2018 were included. Exclusion criteria were age <18 years or recurrent disease. The molecular classification was performed centrally on all tumor samples according to the World Health Organization 2020 classification (including 164 stage IV endometrial cancer patients were molecularly classified. Median age of the patients was 67 years (range 33-86). Most patients presented with a non-endometrioid histological subtype (58%). Intra-abdominal complete cytoreductive surgery was achieved in 60.4% of the patients. 101 tumors (61.6%) were classified as p53 abnormal, 35 (21.3%) as no specific molecular profile, 21 (12.8%) as mismatch repair deficient, and 6 (3%) as The distribution of the molecular subclasses in stage IV endometrial cancer patients differed substantially from the distribution in stage I-III endometrial cancer patients, with the unfavorable subclasses being more frequently present. Although the molecular classification was not prognostic in stage IV endometrial cancer, it could guide adjuvant treatment decisions.

NOTCH Signaling Limits the Response of Low-Grade Serous Ovarian Cancers to MEK Inhibition

Abstract Low-grade serous ovarian cancer (LGSOC) is a rare subtype of epithelial ovarian cancer with high fatality rates in advanced stages due to its chemoresistant properties. LGSOC is characterized by activation of MAPK signaling, and recent clinical trials indicate that the MEK inhibitor (MEKi) trametinib may be a good treatment option for a subset of patients. Understanding MEKi-resistance mechanisms and subsequent identification of rational drug combinations to suppress resistance may greatly improve LGSOC treatment strategies. Both gain-of-function and loss-of-function CRISPR-Cas9 genome-wide libraries were used to screen LGSOC cell lines to identify genes that modulate the response to MEKi. Overexpression of MAML2 and loss of MAP3K1 were identified, both leading to overexpression of the NOTCH target HES1, which has a causal role in this process as its knockdown reversed MEKi resistance. Interestingly, increased HES1 expression was also observed in selected spontaneous trametinib-resistant clones, next to activating MAP2K1 (MEK1) mutations. Subsequent trametinib synthetic lethality screens identified SHOC2 downregulation as being synthetic lethal with MEKis. Targeting SHOC2 with pan-RAF inhibitors (pan-RAFis) in combination with MEKi was effective in parental LGSOC cell lines, in MEKi-resistant derivatives, in primary ascites cultures from patients with LGSOC, and in LGSOC (cell line–derived and patient-derived) xenograft mouse models. We found that the combination of pan-RAFi with MEKi downregulated HES1 levels in trametinib-resistant cells, providing an explanation for the synergy that was observed. Combining MEKis with pan-RAFis may provide a promising treatment strategy for patients with LGSOC, which warrants further clinical validation.

Vulvar and vaginal cancer during pregnancy: A pooled analysis of 15 cases from the International Network on Cancer, Infertility and Pregnancy and review of the literature

Abstract Introduction Vulvovaginal cancer in pregnancy is rare. Limited data complicate decision‐making and patient counseling. Our review, coupled with new case data, fills a current gap in the literature and provides practical insights. Material and Methods Oncological and obstetric data of these pregnancies were examined by a case collection from the International Network on Cancer, Infertility and Pregnancy (INCIP) registry (vulvar n  = 10, vaginal n  = 5) and a literature review (vulvar n  = 46, vaginal n  = 37). Results Although preoperative imaging of inguinofemoral lymph nodes is feasible, only 16.1% of vulvar cancer patients underwent ultrasound or MRI. Treatment was initiated during pregnancy for 69.1% of vulvar cancer and 28.4% of vaginal cancer patients. Surgical lymph node staging of vulvar cancer was postponed until after delivery in 10 cases, although uni‐ or bilateral lymphadenectomy during pregnancy was not associated with more complications. Delivery outcomes included a live birth rate of 96.4% for vulvar cancer and 50% for vaginal cancer due to the high rate of pregnancy terminations, with most births preterm. The overall 5‐year survival rates for vulvar (81.3%) and vaginal (66.4%) cancer during pregnancy are comparable to nonpregnant populations, indicating that pregnancy does not adversely impact maternal prognosis. Conclusions This study underscores the feasibility of adapting standard oncological care for pregnant patients, emphasizing multidisciplinary teams to optimize maternal and fetal outcomes.

Real-world performance of the Assessment of Different NEoplasias in the adneXa (ADNEX) model for the pre-operative classification of ovarian tumors.

To predict the risk of malignancy in ovarian tumors, the multi-class risk prediction Assessment of Different NEoplasias in the adneXa (ADNEX) model of the International Ovarian Tumor Analysis group is used internationally. This study aimed to perform an external validation of this model in a real-world clinical setting in the Netherlands. A multi-center, retrospective diagnostic accuracy study was performed. Women aged ≥18 years who attended the outpatient clinic between May 2020 and December 2021 and had a first ultrasound assessment for an ovarian tumor with application of the International Ovarian Tumor Analysis ADNEX model were included. The reference standard was the pathology result in case of surgery or follow-up with ultrasound according to the current Dutch guideline in case of conservative management. Of the 363 women included, 286 (78.8%) had benign, 24 (6.6%) had borderline, and 53 (14.6%) had malignant pathology. Most (62.5%) of the included patients underwent surgery. The area under the receiver operating characteristic (ROC) curve was 0.92 (95% CI 0.89 to 0.96) if borderline tumors were considered malignant and 0.93 (95% CI 0.89 to 0.96) if borderline tumors were considered benign. Cutoff values between 7% and 14% yielded the highest Youden index. The model was moderately able to differentiate between malignant histologic sub-types. The ADNEX model showed excellent diagnostic performance in daily clinical practice and retained its value in a population in which a proportion of patients were treated with conservative management.

Chemotherapy is not needed when complete evacuation of gestational choriocarcinoma leads to hCG normalization

The standard treatment for gestational choriocarcinoma is chemotherapy. To describe the risk of recurrence with expectant management of gestational choriocarcinoma that has reached a normal human chorionic gonadotropin level after tumor removal without adjuvant chemotherapy. A retrospective multicenter international cohort study was conducted from 1981 to 2017 involving 11 gestational trophoblastic disease reference centers with patient's follow-up extended until 2023. Clinical and biological data of included patients were extracted from each center's database. The inclusion criteria were i) histological diagnosis of gestational choriocarcinoma in any kind of placental tissue retrieved, ii) spontaneous normalization of human chorionic gonadotropin level following choriocarcinoma retrieval, iii) patient did not receive any oncological treatment for the choriocarcinoma, iv) and at least 6 months of follow-up after the first human chorionic gonadotropin level normalization. Among 80 patients with retrieved gestational choriocarcinoma and whose human chorionic gonadotropin level normalized without any other oncological therapy, none had a recurrence of choriocarcinoma after a median follow-up of 50 months. The median interval between choriocarcinoma excision and human chorionic gonadotropin level normalization was 48 days. The International Federation of Gynecology and Obstetrics/World Health Organization risk score was ≤6 in 93.7% of the cases. This multicenter international study reports that selected patients with gestational choriocarcinoma managed in gestational trophoblastic disease reference centers did not experience any relapse when the initial tumor evacuation is followed by human chorionic gonadotropin level normalization without any additional treatment. Expectant management may be a safe approach for highly selected patients.

6Works
10Papers
94Collaborators
Ovarian NeoplasmsNeoplasmsCancer SurvivorsCell Line, TumorNeoplasm Recurrence, LocalGenital Neoplasms, FemaleBiomarkers, Tumor

Positions

Gynecologic Oncologist

Netherlands Cancer Institute - Antoni van Leeuwenhoek Hospital · Gynecologic Oncology