Integrated mutational landscape analysis of poorly differentiated high-grade neuroendocrine carcinoma of the uterine cervix

High-grade neuroendocrine cervical cancers (NETc) are exceedingly rare, highly aggressive tumors. We analyzed 64 NETc tumor samples by whole-exome sequencing (WES). Human papillomavirus DNA was detected in 65.6% (42/64) of the tumors. Recurrent mutations were identified in PIK3CA, KMT2D/MLL2, K-RAS, ARID1A, NOTCH2, and RPL10. The top mutated genes included RB1, ARID1A, PTEN, KMT2D/MLL2, and WDFY3, a gene not yet implicated in NETc. Somatic CNV analysis identified two copy number gains (3q27.1 and 19q13.12) and five copy number losses (1p36.21/5q31.3/6p22.2/9q21.11/11p15.5). Also, gene fusions affecting the ACLY-CRHR1 and PVT1-MYC genes were identified in one of the eight samples subjected to RNA sequencing. To resolve evolutionary history, multiregion WES in NETc admixed with adenocarcinoma cells was performed (i.e., mixed-NETc). Phylogenetic analysis of mixed-NETc demonstrated that adenocarcinoma and neuroendocrine elements derive from a common precursor with mutations typical of adenocarcinomas. Over one-third (22/64) of NETc demonstrated a mutator phenotype of C > T at CpG consistent with deficiencies in MBD4, a member of the base excision repair (BER) pathway. Mutations in the PI3K/AMPK pathways were identified in 49/64 samples. We used two patient-derived-xenografts (PDX) (i.e., NET19 and NET21) to evaluate the activity of pan-HER (afatinib), PIK3CA (copanlisib), and ATR (elimusertib) inhibitors, alone and in combination. PDXs harboring alterations in the ERBB2/PI3K/AKT/mTOR/ATR pathway were sensitive to afatinib, copanlisib, and elimusertib (P < 0.001 vs. controls). However, combinations of copanlisib/afatinib and copanlisib/elimusertib were significantly more effective in controlling NETc tumor growth. These findings define the genetic landscape of NETc and suggest that a large subset of these highly lethal malignancies might benefit from existing targeted therapies.

Preclinical efficacy of RAF/MEK clamp avutometinib in combination with FAK inhibition in low grade serous ovarian cancer

OBJECTIVES

Low-grade-serous-ovarian-carcinoma (LGSOC) is characterized by a high recurrence rate and limited therapeutic options. About one-third of LGSOC contains mutations in MAPK pathway genes such as KRAS/NRAS/BRAF. Avutometinib is a dual RAF/MEK inhibitor while defactinib and VS-4718 are focal-adhesion-kinase-inhibitors (FAKi). We determined the preclinical efficacy of avutometinib±VS-4718 in LGSOC patient-derived-tumor-xenografts (PDX).

METHODS

Whole-exome-sequencing (WES) was used to evaluate the genetic fingerprint of 3 patient-derived LGSOC (OVA(K)250, PERIT(M)17 and A(PE)148). OVA(K)250 tissue was successfully xenografted as PDX into female CB17/lcrHsd-Prkdc/SCID-mice. Animals were treated with either control, avutometinib, VS-4718, or avutometinib/ VS-4718 once daily five days on and two days off through oral gavage. Mechanistic studies were performed ex vivo using avutometinib±defactinib treated LGSOC tumor samples by western blot.

RESULTS

WES results demonstrated wild-type KRAS in all 3 LGSOC. OVA(K)250 PDX showed gain-of-function mutations (GOF) in PTK2 and PTK2B genes, and loss-of-heterozygosity in ADRB2, potentially sensitizing to FAK and RAF/MEK inhibition. The combination of avutometinib/ VS-4718 demonstrated strong tumor-growth inhibition compared to controls starting at day 9 (p < 0.002) in OVA(K)250PDX. By 60 days, mice treated with avutometinib alone and avutometinib/VS-4718 were still alive; compared to median survival of 20 days in control-treated mice and of 35 days in VS-4718-treated mice (p < 0.0001). By western-blot assays exposure of OVA(K)250 to avutometinib, FAKi defactinib and their combination demonstrated decreased phosphorylated FAK (p-FAK) as well as decreased p-ERK.

CONCLUSION

Avutometinib, and to a larger extent its combination with FAK inhibitor VS-4718, demonstrated promising in vivo activity against a KRAS wild-type LGSOC-PDX. These data support the ongoing registration-directed study (RAMP201/NCT04625270).

Uterine leiomyosarcomas harboring MAP2K4 gene amplification are sensitive in vivo to PLX8725, a novel MAP2K4 inhibitor

INTRODUCTION

Uterine leiomyosarcomas (uLMS) are rare, highly aggressive tumors. Up to 30% of uLMS may harbor gain of function (GOF) in the MAP2K4 gene, important for tumor cell proliferation, differentiation and metastasis. We investigated the in vivo activity of a novel MAP2K4 inhibitor, PLX8725, against uLMS harboring MAP2K4 gene-amplification.

METHODS

Two fully characterized uLMS (i.e., LEY-11 and LEY-16) were grafted into female CB-17/SCID mice. Treatments with control vehicle or PLX8725 (50 mg/kg) were given via oral gavage daily on weekdays for up to 60 days. Tumor volume differences were calculated with two-way ANOVA. Pharmacokinetic (PK) and mechanistic studies of PLX8725 in uLMS PDX models were also performed.

RESULTS

Both uLMS tumors evaluated demonstrated GOF in MAP2K4 (i.e., 3 CNV in both LEY-11 and LEY-16). Tumor growth inhibition was significantly greater in both PDX LEY-11 and PDX LEY-16 treated with PLX8725 when compared to controls (p < 0.001). Median overall survival was also significantly longer in both PDX LEY-11 (p = 0.0047) and PDX LEY-16 (p = 0.0058) treatment cohorts when compared to controls. PLX8725 oral treatment was well tolerated, and PK studies demonstrated that oral PLX8725 gives extended exposure in mice. Ex vivo tumor samples after PLX8725 exposure decreased phosphorylated-ATR, JNK and p38, and increased expression of apoptotic molecules on western blot.

CONCLUSION

PLX8725 demonstrates promising in vivo activity against PDX models of uLMS harboring GOF alterations in the MAP2K4 gene with tolerable toxicity. Phase I trials of PLX8725 in advanced, recurrent, chemotherapy-resistant uLMS patients are warranted.

Abstract 3402: In vivo efficacy of RAF/MEK clamp avutometinib (VS-6766) in combination with FAK inhibition in low grade serous ovarian cancer

Objective: Low grade serous carcinoma (LGSC) of the ovary is characterized by a high recurrence rate, resistance to most chemotherapeutic agents, and limited effective therapeutic options. Recently, LGSC has been found to often contain mutations in KRAS (~30%), NRAS (~10%), and BRAF (~8%). Avutometinib (VS-6766) is a RAF/MEK clamp that induces dominant negative complexes of RAF with MEK, and inhibits proliferation of KRAS, NRAS, BRAF, and CRAF mutant cell lines. VS-4718 is a focal adhesion kinase (FAK) inhibitor that has shown synergistic anti-tumor activity with avutometinib in other cancer models, as it blocks the potential of FAK to function as an adaptive resistance mechanism to RAF/MEK inhibition. This study aimed to determine the efficacy of the RAF/MEK clamp avutometinib with FAK inhibition in vivo in LGSC patient derived tumor xenograft (PDX) models.

Methods: Whole-exome sequencing was used to evaluate mutations in two primary ovarian LGSC PDX models (OVA(K)250 and PERIT(M)17). OVA(K)250 and PERIT(M)17 cells were injected into SCID mice and animals were treated with either vehicle control (CTRL), RAF/MEK clamp avutometinib (MEKi), FAK inhibitor VS-4718, or the combination (MEKi/FAKi). Tumor volumes were measured twice per week.

Results: Both the OVA(K)250 and PERIT(M)17 PDX models express wildtype KRAS and express RAF1 mutations at position 12641679 A&gt;C, V207G. In PDX OVA(K)250 mice treated with MEKi/FAKi, day 9 tumor volume was significantly lower compared to mice treated with CTRL (p=0.0002). At day 9, tumor volume was also significantly lower in mice treated with MEKi alone compared to CTRL (p=0.0007). Mice treated with FAKi alone had tumor volumes that were significantly smaller than CTRL by day 12 (p=0.009). By day 23, CTRL mice had reached tumor volume characteristics requiring sacrifice. Combination MEKi/FAKi treatment resulted in improved overall survival (OS); median OS for combination or MEKi alone was not reached by 60 days. Treatment with FAKi led to median OS of 35 days; CTRL mice had median OS of 23 days (p=0.001). In vivo experiments with PDX PERIT(M)17 and PDX OVA(K)250 are ongoing.

Conclusion: Combination of avutometinib with FAK inhibition showed improved in vivo preclinical anti-tumor efficacy relative to either agent alone in an LGSC PDX model with wildtype KRAS and with a RAF1 mutation. These data support an ongoing registration-directed study with avutometinib ± the FAK inhibitor defactinib for patients with recurrent LGSC (NCT04625270).

Citation Format: Blair McNamara, Cem Demirkiran, Stefania Bellone, Levent Mutlu, Margherita Zipponi, Miguel S. Verzosa, Justin Harold, Tobias M. Hartwich, Gary Altwerger, Elena Ratner, Gloria Huang, Mitchell Clark, Vaagn Andikyan, Masoud Azodi, Peter E. Schwartz, Peter Dottino, Alessandro D. Santin. In vivo efficacy of RAF/MEK clamp avutometinib (VS-6766) in combination with FAK inhibition in low grade serous ovarian cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 3402.

Trastuzumab deruxtecan (DS-8201a), a HER2-targeting antibody-drug conjugate with topoisomerase I inhibitor payload, shows antitumor activity in uterine and ovarian carcinosarcoma with HER2/neu expression

OBJECTIVES

Carcinosarcomas are highly aggressive gynecologic malignancies containing both carcinomatous and sarcomatous elements with heterogeneous HER2/neu expression and limited therapeutic options. We compared the efficacy of trastuzumab deruxtecan (DS-8201a), a novel HER2/neu-targeting antibody-drug conjugate (ADC) to an ADC isotype control (MAAA-9199) against primary uterine and ovarian carcinosarcomas in vitro and in vivo.

METHODS

Twelve primary carcinosarcoma (CS) cell lines were evaluated for HER2/neu surface expression by immunohistochemistry (IHC) and by flow cytometry, and gene amplification by fluorescence in situ hybridization (FISH) assays. The in vitro experiments included cytotoxicity and bystander killing effect assays on three cell lines of variable HER2/neu expression. In vivo activity was studied in a mouse CS xenograft model of 3+ HER2/neu uterine CS.

RESULTS

In vitro studies showed that DS-8201a was highly effective against uterine and ovarian CS cell lines demonstrating 3+ HER2/neu expression compared to MAAA-9199 control; there was no significant improvement in the 0 HER2/neu CS cell line. However, DS-8201a induced efficient bystander killing of 0 HER2/neu tumor cells when admixed with 3+ HER2/neu cells. In vivo studies confirmed that DS-8201a was more effective than MAAA-9199 in 3+ HER2/neu-expressing CS xenografts.

CONCLUSION

DS-8201a may represent a novel and highly effective ADC against HER2/neu-expressing CS.

The Poly (ADP-ribose) polymerase inhibitor olaparib and pan-ErbB inhibitor neratinib are highly synergistic in HER2 overexpressing epithelial ovarian carcinoma in vitro and in vivo

INTRODUCTION

Ovarian cancer (OC) is associated with the highest gynecologic cancer mortality. The development of novel, effective combinations of targeted therapeutics remains an unmet medical need. We evaluated the preclinical efficacy of the Poly (ADP-ribose) polymerase (PARP) inhibitor (olaparib) and the pan-ErbB inhibitor (neratinib) as single agents and in combination in ovarian cancer cell lines and xenografts with variable HER2 expression.

METHODS

In vitro cell viability with olaparib, neratinib, and their combination was assessed using flow-cytometry based assays against a panel of OC primary cell lines with variable HER2 expression. Immunoblotting experiments were performed to elucidate the mechanism of activity and synergism. The in vivo antitumor activity of the olaparib/neratinib combination versus single agents was tested in HER2 positive xenograft OC models.

RESULTS

HER2 + OC cell lines demonstrated higher sensitivity to olaparib and neratinib when compared to HER2 negative tumors (i.e., IC50: 2.06 ± 0.33 μM vs. 39.28 ± 30.51 μM, p = 0.0035 for olaparib and 19.42 ± 2.63 nM vs. 235.0 ± 165.0 nM, p = 0.0035 for neratinib). The combination of olaparib with neratinib was more potent when compared to single-agent olaparib or neratinib both in vitro and in vivo, and demonstrated synergy in all primary HER2 + OC models. Western blot experiments showed neratinib decreased pHER2/neu while increased Poly(ADP-ribose) (PAR) enzymatic activity; olaparib increased pHER2/Neu expression and blocked PAR activatio. Olaparib/neratinib in combination decreased both pHER2/Neu as well as PAR activation.

CONCLUSION

The combination of olaparib and neratinib is synergistic and endowed with remarkable preclinical activity against HER2+ ovarian cancers. This combination may represent a novel therapeutic option for ovarian cancer patients with HER2+, homologous recombination-proficient tumors resistant to chemotherapy.

Ovarian and uterine carcinosarcomas are sensitive in vitro and in vivo to elimusertib, a novel ataxia-telangiectasia and Rad3-related (ATR) kinase inhibitor

BACKGROUND

Carcinosarcoma of the ovary (OCS) and uterus (UCS) are rare highly aggressive malignancies. Ataxia-telangiectasia-and-Rad3-related (ATR) kinase and homologous recombination play a pivotal role in DNA damage repair. Homologous recombination deficiency (HRD) has been demonstrated in >30% of OCS/UCS. We investigated the preclinical activity of elimusertib, a selective ATR kinase inhibitor, against carcinosarcoma (CS) cell lines and xenografts.

METHODS

Sensitivity to elimusertib was evaluated in vitro against nine whole exome-sequenced (WES) primary CS cell lines and in vivo against HRD CS xenografts. Western blots were performed to determine baseline ATR and p-ATR protein expression in CS, and ATR pathway downstream effectors and apoptosis markers in CS HRD cell lines after Elimusertib treatment.

RESULTS

Out of the 9 CS cell lines, 3 harbored HRD and 6 homologous recombination proficient (HRP) features. Most of CS (i.e., 7/9 = 85%) were found to be sensitive to Elimusertib in vitro. Among the 5 primary CS cell lines with a high-grade pure serous epithelial component, HRD cell lines were more sensitive to elimusertib than HRP tumors (mean IC50 ± SEM HRD CS = 61.3 nM ±15.2 vs HRP = 361.6 nM ±24.4 (p = 0.01)). Baseline ATR and p-ATR protein expression was higher in HRD CS cell lines. Elimusertib showed tumor growth inhibition in HRD CS xenografts (p < 0.0001) and increased overall animal survival (p < 0.0001). Western blot demonstrated dose-dependent inhibition of ATR, p-ATR and its downstream effector p-CHK1, and a dose-dependent increase in caspase-3 expression.

CONCLUSIONS

Elimusertib is preclinically active in vitro and in vivo against primary CS cell lines and xenografts, respectively. CS models harboring HRD or with pure/mixed endometrioid histology demonstrated higher sensitivity to ATR inhibition. Clinical trials with elimusertib in CS patients are warranted.

Elimusertib (BAY1895344), a novel ATR inhibitor, demonstrates in vivo activity in ATRX mutated models of uterine leiomyosarcoma

INTRODUCTION

Uterine leiomyosarcoma (uLMS) is a rare, highly aggressive malignancy. Recent data suggest 50% of uLMS may harbor alterations in the ATRX gene and such mutations may confer sensitivity to ataxia-telangiectasia-and-Rad3-related (ATR) kinase inhibitors. We sought to investigate the in vivo activity of Elimusertib (BAY1895344), a novel ATR-inhibitor, against ATRX-mutated uLMS patient-derived xenografts (PDXs).

METHODS

Two fully characterized uLMS (i.e., LEY-11 and LEY-16) were grafted into female CB-17/SCID mice. Treatments with control vehicle or BAY1895344 (20 mg/kg dosed twice daily 3 days on 4 days off) were given via oral gavage and tumor measurements as well as weights obtained twice weekly. Tumor volume differences were calculated with a two-way ANOVA. Mechanistic studies were performed ex vivo using BAY1895344 treated uLMS tumor samples by western blot analysis.

RESULTS

Both PDX LEY-11 and PDX LEY-16 harboring ATRX gene mutations demonstrated an aggressive behavior in vivo (i.e., control mice were euthanized on average at day 12.5 for PDX LEY-11 and at day 33 for PDX LEY-16). In both tumor models BAY1895344 20 mg/kg dosed with an intermittent oral schedule was able to induce significant growth inhibition compared to vehicle control treatment (p < 0.001 for both LEY-11 and LEY-16) and prolong median overall survival [PDX LEY-11 (12.5 vs. 42 days, p < 0.001) and PDX LEY-16 (33 vs. 60 days, p < 0.001)]. There were not significant changes in weight between treatment and controls. By western blot assays BAY1895344 exposure decreased phosphorylated-ATR and increased expression of apoptotic molecules in LMS PDXs.

CONCLUSIONS

BAY1895344 demonstrates promising in vivo activity against biologically aggressive PDX models of uLMS harboring ATRX mutations, with no significant toxicity. Clinical trials of BAY1895344 in uLMS patients are warranted.