A Durable Response to Pembrolizumab in a Patient with Uterine Serous Carcinoma and Lynch Syndrome due to the MSH6 Germline Mutation

Pembrolizumab, a programmed death 1 ligand (PD-1) checkpoint inhibitor, has elicited responses in mismatch repair (MMR)-deficient advanced solid tumors, leading to its agnostic approval by the US Food and Drug Administration in 2017 when no other therapeutic options are available. However, there are still insufficient data on the response to checkpoint inhibitors in advanced endometrial cancer related to Lynch syndrome (LS) and, specifically, in uterine serous carcinoma, which is uncommon in LS. Here we report a case of metastatic uterine serous carcinoma due to a germline MSH6 mutation (Lynch syndrome) that was discovered because of a patient's tumor MMR deficiency. The patient was started on first-line pembrolizumab in 2018 and sustained a partial response. She remains asymptomatic and progression free for more than 2 years. Tumor sequencing showed a high mutational burden and an upstream somatic mutation in the same gene, p.F1088fs. Immunohistochemical staining was negative for PD-L1 expression. We discuss clinical characteristics of the patient, molecular features of her tumor, and the mechanism of her tumor response. We also discuss the duration of immunotherapy in her case. Our case demonstrated a partial response and a long-term remission from the frontline single-agent pembrolizumab in a woman with metastatic uterine serous carcinoma and Lynch syndrome due to a germline MSH6 gene mutation. Our experience suggests a potential significant clinical benefit of checkpoint inhibitors used as single agents early on in the treatment of MMR-deficient/high microsatellite instability/hypermutated uterine cancers in women with Lynch syndrome. KEY POINTS: Even though checkpoint inhibitors are effective in mismatch repair-deficient endometrial cancer, it is unknown whether the response to them differs between women with endometrial cancer due to germline mutations in a mismatch repair gene (Lynch syndrome) and women with sporadic endometrial cancer. In our case, a patient with Lynch syndrome and recurrent mismatch repair-deficient serous endometrial cancer achieved a durable remission on the first-line therapy with the checkpoint inhibitor pembrolizumab and remains progression free after more than 2 years. Based on our observation and the data, suggesting the stronger immune activation in women with Lynch syndrome-associated endometrial cancer, we propose to use checkpoint inhibitor monotherapy early in the course of their treatment and stratify patients for the presence of Lynch syndrome in clinical trials.

Paired tumor sequencing and germline testing in breast cancer management: An experience of a single academic center

BACKGROUND

Genetic testing for cancer predisposition is recommended to women with breast cancer who meet the criteria for such testing. After the FDA approvals of the poly ADP ribose polymerase (PARP) inhibitors, olaparib and talazoparib, for treatment of metastatic breast cancer, carrying germline mutations in BRCA1 and BRCA2 genes, the genetic testing result has become critical in their care. With the recent FDA approval of alpelisib for the treatment of PIK3CA-mutated hormone-receptor positive metastatic breast cancer, tumor molecular profiling to identify somatic mutations and potential molecularly targeted agents is increasingly utilized in the treatment of advanced breast cancer.

AIM

Combining germline and somatic sequencing (paired testing) offers an advantage over a single technique approach. Our study evaluates the role of paired testing on the management of breast cancer patients.

METHODS AND RESULTS

Forty-three breast cancer patients treated at Rush University Medical Center underwent paired germline and somatic variant testing in 2015 to 2017. A retrospective chart review was conducted with the analysis of demographic, clinical, and genomic data. Three actionable germline variants were found in the CHEK2 (2) and ATM (1) genes. 95% of tumors had somatic mutations. Seventy-seven percent of tumors had genomic alterations targetable with agents approved for breast cancer and 88% had molecular targets for agents approved for other cancers. Clinical examples of such use are described and potential future directions of tumor and paired testing are discussed.

CONCLUSIONS

Germline variants were present in a relatively small patient group not routinely tested for inherited alterations. Potentially targetable somatic alterations were identified in the majority of breast cancers. Paired testing is a feasible and efficient approach that delivers valuable information for the care of breast cancer patients and eliminates serial testing.

Abstract 3586: Epigenetic influence on ethnic disparities in non-small cell lung cancer

African Americans are more likely to develop lung cancer and die from it than any other ethnic group. Complex biological, environmental, political and cultural factors contribute to this disparity. The purpose of the current project is to examine the relationship between epigenetic factors, gender, ethnicity and outcome in a retrospective study of patients with surgically-treated early stage lung cancer. Fixed primary tumor tissues from a private (RMC) and a public (JHS-CCH) institution were analyzed in this study. The RMC group consisted of 132 patients with stage Ib, IIa and IIb NSCLC, 22% African-American (AA) and 52% female. The JHS-CCH group consisted of 88 patients, 62% AA and 43% female. Five year survival was achieved by 85% of women vs 67% of men in the RMC group (Chi square p=0.022). 68% of Caucasians vs 53% AA survived five years in the RMC group (p=0.186). To investigate the role of epigenetic influences on survival, promoter methylation of Ras association domain family protein 1, RASSF1A, was investigated. Associations between inactivation of the RASSF1A tumor suppressor and poor outcome in lung and other cancers have been reported in several studies. Promoter methylation was quantified using pyrosequencing. Percent methylation of RASSF1 at cytosine position –36 (A of ATG=+1) was more frequent in AA (41% of cases) than in Caucasians (20% of cases) in the RMC group (p=0.023) compared to 69% of cases in the JHS-CCH group. Methylation levels of RASSF1 at all CpG sites tested were higher in the JHS-CCH group than in the RMC group. Kaplan-Meier analysis was performed on dichotomized hypermethylation status compared to five-year survival (5YS). Promoter hypermethylation of RASSF1 was significantly associated with shortened 5YS in AA (p=0.005), compared to Caucasians (p=0.197) in the RMC group. Although 5YS was marginally shortened with hypermethylation of RASSF1 in men in the RMC group (p=0.123), no significant effects were seen with regard to gender. These results suggest that biomarkers can have differential effects, based on genetic background and support analysis of epigenetic biomarkers to address disparities and develop more personalized treatment strategies for individual patients.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 3586. doi:1538-7445.AM2012-3586

Abstract 3831: Functional and epigenetic regulation of SHP-1 in early stage lung cancer

SHP-1 tyrosine phosphatase potentiates mitogenic signalling cascades in multiple cellular pathways by dephosphorylating inhibitory phospho-tyr sites on kinases. With its central role in regulation of cell proliferation, SHP-1 is a logical candidate biomarker for malignant transformation. SHP-1 dephosphorylates a number of phospho-targets including PI3 kinase, EGFR, src family kinases (SFK), and activated cKit, hence normally has a negative impact on cell proliferation. SHP-1 protein function is highly regulated by phosphorylation with up regulation at tyr536, and down regulated by ser591 phosphorylation. The objectives of the present study are to investigate functional control of SHP- 1 and epigenetic control of expression in non small cell lung cancer (NSCLC). In our previous study, Western blot analyses revealed inhibitory ser591 phosphorylation in two of five NSCLC cell lines that expressed high levels of SHP1. We now observe that si-RNA silencing of the major SFK expressed in the EGFR constitutively activated Calu3 cells results in decreased tyr536 phosphorylation suggesting that SFK are required for SHP-1 activity.

Transcription of the SHP-1 gene is regulated by two different promoters: a 3’ promoter (promoter 2) in lymphocytes and a 5’ promoter (promoter 1) in epithelial tissues. Gene silencing of SHP-1 by aberrant methylation of promoter 2 and loss of heterozygosity have been associated with pathogenesis of leukemias/lymphomas. Altered expression of SHP-1 has been reported in ovarian and breast cancer due to epigenetic changes in the 5’ promoter (promoter 1). Promoter 2 hypermethylation has been proposed as a plasma biomarker for lung cancer. Previous observations are consistent with the involvement of aberrant SHP-1 promoter 2 methylation in recurrent cases of NSCLC. Pyrosequencing analysis of 22 normal leukocytes, 19 normal lung specimens, 112 cases of early stage (Ib, IIa and IIb) NSCLC and 8 cell lines of SHP-1 promoter 1 vs promoter 2 methylation revealed 10.2% vs 5.1% in leukocytes, 32.6% vs 52.9% in normal lung 44.4% vs 58.6% in NSCLC, and 50.6% vs 96.2% in the cell lines. Hypermethylation of SHP-1 promoter 1 and promoter 2 were observed in 40.8% and 60.7% of lung tumors, respectively. Previous results showed an association of hypermethylation of promoter 2 with time to tumor recurrence in early stage patients (p=0.010). Hypermethylation of SHP-1 promoter 1 in the present study with a limited number of samples is marginally associated with shorter time to recurrence (25.5 months vs. median not reached; p=0.219). These results demonstrate tissue-specific epigenetic control of both SHP-1 promoters and suggest dysfunction of both epigenetic and post-translational regulation of signalling in early stage NSCLC.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 3831. doi:10.1158/1538-7445.AM2011-3831

Abstract 4120: SHP-1 tyrosine phosphatase in early stage lung cancer

SHP-1 tyrosine phosphatase potentiates mitogenic signalling cascades in multiple cellular pathways, by dephosphorylating inhibitory phospho-tyr sites on kinases. The SHP-1 gene is highly expressed from a 3′ promoter (promoter 2) in lymphocytes, but not in lymphomas or leukemic cells. Gene silencing of SHP-1 by aberrant methylation and loss of heterozygosity has been associated with the pathogenesis of leukemias/lymphomas. With its central role in regulation of cell proliferation, SHP-1 is a logical candidate biomarker for malignant transformation, however, its role in solid tissues is unclear. SHP-1 dephosphorylates a number of phospho-targets including PI3 kinase, EFGR, src family kinases, and activated cKit, the stem cell factor receptor. Dephosphorylation of inhibitory phospho-tyr sites in these kinases results in increased signaling and gene expression. In the present study, western blot analyses of protein expression in two of four NSCLC cell lines which reportedly have silenced SHP-1 but had elevated levels of SHP-1 protein revealed inhibitory ser591 phosphorylation suggesting that this phosphatase was not activated in those cells. Altered expression of SHP-1 in leukemias and lymphomas was recently shown to be associated with clinical stage and pathogenesis with decreased levels evident in residual disease. Furthermore, altered expression of SHP-1 in epithelial tumors has been reported in ovarian and breast cancer, due to changes in the 5′ promoter (promoter 1) methylation. Previous observations by ourselves and others are consistent with the involvement of aberrant tumor suppressor gene promoter methylation in non-small cell lung cancer (NSCLC) particularly in recurrent cases. To investigate the role of epigenetic regulation of SHP-1 promoter 2 methylation in NSCLC, we used pyrosequencing to quantify methylation in 22 normal blood leukocytes, 19 normal lung specimens, 112 cases of early stage (Ib, IIa and IIb) NSCLC and 8 cell lines. Average SHP-1 promoter 2 methylation was 5.1% in leukocytes, 52.9% in normal lung 58.6% in NSCLC, and 96.2% in the cell lines. Promoter hypermethylation of SHP-1 (defined as more than 55% methylated) was observed in 68/112 of lung tumors. When compared to those tumors with methylation less than 55%, hypermethylation of SHP-1 at position −449 (+6025) was associated with shorter time to recurrence (51.4 months vs. 112 months; p=0.010) and marginally associated with five year survival (92.0 months vs. 125 months; p=0.073). These results demonstrate tissue-specific epigenetic control of SHP-1 promoter 2 and suggest a role for promoter 2-regulated signalling in early stage NSCLC. Furthermore, considering the relative low levels of SHP1 protein expression detected in the lung cancer cell lines, SHP-1 promoter 1 methylation in NSCLC is currently under investigation.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 4120.

The Prognostic Value of Chromosome 7 Polysomy in Non-small Cell Lung Cancer Patients Treated with Gefitinib

INTRODUCTION

Specific subpopulations of non-small cell lung cancer (NSCLC) patients defined by clinical features and molecular profiles seem to derive greater benefit from epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors, but no general consensus on molecular testing to optimize treatment has emerged. The objective of this study was to evaluate chromosome 7 polysomy and other potential indicators of gefitinib efficacy in advanced NSCLC patients.

METHODS

Paraffin-embedded tumors from 82 patients treated with gefitinib were analyzed by immunohistochemistry for expression of EGFR and other markers, and by fluorescence in situ hybridization for EGFR gene or chromosome copy number. Mutational status was assessed by single-strand conformational polymorphism, sequence-specific polymerase chain reaction, and direct sequencing. Molecular and clinical characteristics were evaluated in relation to objective response (OR), progression-free survival (PFS), and overall survival (OS).

RESULTS

EGFR mutational status (p = 0.002), never smoking (p = 0.052), and chromosome 7 polysomy (p = 0.029) were significant indicators of OR. EGFR mutation, pAKT or PTEN expression, and chromosome 7 polysomy were associated with longer OS. There was a significant difference in OS between the chromosome 7 polysomy groups (p = 0.015) and the groups with both chromosome 7 polysomy and pAkt (p = 0.002) and both chromosome7 polysomy and PTEN (p = 0.04). In a stepwise proportional hazards analysis, chromosome 7 polysomy and PTEN expression were both significantly associated with longer OS (p = 0.004 and 0.017 respectively).

CONCLUSION

These results suggest that further study of chromosome 7 polysomy and of pAKT and PTEN expression in patients treated with EGFR tyrosine kinase inhibitors is warranted in developing a clinical test for selecting patients for gefitinib therapy.

Inhibition of cytarabine-induced MDR1 (P-glycoprotein) gene activation in human tumor cells by fatty acid-polyethylene glycol-fatty acid diesters, novel inhibitors of P-glycoprotein function

Fatty acid ester surfactants Cremophor EL and Solutol HS 15 were described earlier as modulators of multidrug resistance mediated by MDR1 P-glycoprotein (Pgp). We have shown that the most active components of these polydisperse surfactants are fatty acid-polyethylene glycol-fatty acid diesters (FA-PEG-FA). A new generation of Pgp-surfactant inhibitors of defined structure was therefore synthesized. In the present study we show that these compounds are also able to inhibit up-regulation of MDR1 gene expression caused by cytarabine (ARA-C) and doxorubicin in human tumor cell lines H9 and KB 3-1, which express minimal levels of MDR1 mRNA. The surfactant inhibitors, however, had no effect on the induction of MDR1 gene expression by protein kinase C agonists. Using a set of FA-PEG-FA diesters with various fatty acids and different lengths of the PEG domain, we demonstrated that the activity of diester preparations as inhibitors of drug-induced MDR1 activation was in proportion to their activity as inhibitors of Pgp function. Oleic and stearic acid diesters with PEG 900 (20 ethylene oxide units) were the most potent. The poloxamer analogs of these diesters demonstrated similar effects. In contrast, the well-known, structurally unrelated inhibitors of Pgp activity, verapamil, cyclosporin A and PSC 833, had no inhibitory effect on drug-induced MDR1 activation. The ability of FA-PEG-FA diesters to inhibit both Pgp function and drug-induced MDR1 activation suggests that these chemomodulators may be uniquely useful for the prophylaxis of Pgp-mediated multidrug resistance in drug-treated tumors.

Reversal of multi-drug resistance in vitro by fatty acid-PEG-fatty acid diesters

Fatty acid ester surfactants, e.g., Cremophor EL and Solutol HS 15, that modulate multi-drug resistance (MDR) have been described; however, the drug potential of these preparations is unclear because of the molecular heterogeneity of these and other commercial surfactants. In previous experiments, an active but still polydisperse preparation, designated CRL 1337, was synthesized by reacting purified oleic acid with a 20-fold molar excess of ethylene oxide. We have subjected this preparation to chromatographic separation, and infrared analysis of the active fractions revealed a significant component of diester structures (fatty acid-PEG-fatty acid). A new generation of diester compounds has now been synthesized. Preparations comprised of 99% diesters were significantly more potent than monoester preparations for MDR modification activity in vitro. As previously determined for ethylene oxide-derived preparations similar to CRL 1337, the nature of the fatty acid domains proved to be important for activity, as was the relative length of the polyethylene glycol domain (which determines the hydrophile-lipophile balance). The ester linkage appeared unimportant since homologous diethers and diamides had activity similar to that of diesters. Stearic acid diester was 1.5- to 7-fold more potent than CRL 1337 when tested in cell proliferation inhibition assays. In light of these structural restrictions on drug potentiation, and since these surfactants are active at relatively low concentrations (below 1 microgram/ml), investigations of their mechanism of action were initiated by exploring specific interactions with P-glycoprotein. Both active and inactive diesters inhibited azidopine labeling of P-glycoprotein, suggesting that fatty acid-PEG diesters can interfere with P-glycoprotein substrate binding. Other attributes of these preparations must contribute to their ability to reverse MDR.

Comparison of solutol HS 15, Cremophor EL and novel ethoxylated fatty acid surfactants as multidrug resistance modification agents

Some well-known fatty acid ester surfactants, e.g., Cremophor EL and Solutol HS 15, are modulators of multidrug resistance in vitro and in vivo. Because they are polydisperse, and their active component(s) have not been identified, the therapeutic potential of such surfactants is unclear. To better define the active components of Solutol HS 15 and to make more potent surfactant multidrug resistance modulators, highly purified C-18 fatty acids were esterified with ethylene oxide at 5-200 molar ratios. Unexpectedly, ethylene oxide esters of pure 12-hydroxy stearic acid, the major components of Solutol HS 15, displayed negligible resistance modification activity compared with Solutol HS 15 itself or to stearic and oleic acid esters synthesized under identical conditions. Since oleic acid esters appeared to have good activity, a series of these compounds was prepared to determine the optimal ethylene oxide/fatty acid ratio. The optimal ratio was found to be 20 mole ethylene oxide: I mole fatty acid, with a steep decline in activity for products made with ratios above and below the optimum. The most active oleic acid ester, designated CRL 1337, was 8.4-fold as potent as Solutol HS 15 and over 19-fold as potent as Cremophor EL in promoting rhodamine 123 accumulation in multidrug-resistant KB 8-5-11 cells in vitro. Our results show that the structure of the hydrophobic domain (fatty acid) of surfactants as well as its hydrophile-lipophile balance are critical in determining the potency of surfactants as reversing agents.

Nucleotide sequence and promoter analysis of SPO13, a meiosis-specific gene of Saccharomyces cerevisiae

The SPO13 gene, required for meiosis I segregation in Saccharomyces cerevisiae, produces two developmentally regulated transcripts (1.0 and 1.4 kilobases) that differ in length at their 5' ends. The shorter transcript is sufficient to complement the spo13-1 mutation and contains a major open reading frame encoding a highly basic protein of 33.4 kilodaltons. A fragment upstream (-170 to -8) of the open reading frame confers meiosis-specific transcription on a spo13-HIS3 fusion. Deletions at the 5' end of spo13-lacZ fusions define a region between -140 and -80 that is essential for meiosis-specific expression. This region acts in an orientation-independent manner and is responsive to the MAT-RME regulatory cascade. It contains a 10-base-pair sequence, TAGCCGCCGA, found in a number of meiosis-specific genes, that appears to be required for SPO13 expression. This sequence is identical to URS1, a ubiquitous mitotic repressor element.