Abstract 2755: Identification of novel GPX4 inhibitors using global transcriptional reporters

Induction of Ferroptosis is a promising strategy for treating therapy-resistant tumors including mesenchymal tumor types. We performed a phenotypic screen to identify small molecules that induce ferroptosis in mesenchymal cancer cells by screening for compounds whose toxicity could be rescued by the lipophilic antioxidant Ferrostatin-1. To identify compounds that induce GPX4-mediated ferroptosis, we identified several pharmacodynamic biomarkers specific to GPX4 inhibition using our nascent RNA sequencing platform, which allows for time-resolved snapshots of global transcription. We measured the transcriptional changes that occur in the hours following inhibition of GPX4 and identified HMOX1 as a robust biomarker of GPX4i-induced ferroptosis in mesenchymal cancer cell lines. Using HMOX1-induction as a guide, we uncovered a small number of compounds as potential GPX4 inhibitors. One such compound was validated as a bonafide GPX4 inhibitor through a variety of biochemical assays and selected for a hit-to-lead campaign. In addition to standard medicinal chemistry strategies, we are currently employing a newly-developed global transcriptional reporter system to stratify several novel series of GPX4 inhibitors by their transcriptional signatures. This approach represents a unique strategy for determining on- and off- target effects of a compound and for defining structure activity relationships within a chemical series.

Citation Format: Timothy Read, Zoe Winigrad, Ardeshir Goliaei, Cole Liechty, Carter Grochala, Leah Damon, John Dickson, Jason Harris, Casey Pham, Jenna Rimel, Christy Rhine, Dave Simpson, Eric Martin, Joey Azofeifa. Identification of novel GPX4 inhibitors using global transcriptional reporters [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 2755.

Targeting FGFR overcomes EMT-mediated resistance in EGFR mutant non-small cell lung cancer

Evolved resistance to tyrosine kinase inhibitor (TKI) targeted therapies remains a major clinical challenge. In EGFR mutant non-small cell lung cancer (NSCLC), failure of EGFR TKIs can result from both genetic and epigenetic mechanisms of acquired drug resistance. Widespread reports of histologic and gene expression changes consistent with an epithelial-to-mesenchymal transition (EMT) have been associated with initially surviving drug tolerant persister cells, which can seed bona fide genetic mechanisms of resistance to EGFR TKIs. While therapeutic approaches targeting fully resistant cells, such as those harboring an EGFR^T790M mutation, have been developed, a clinical strategy for preventing the emergence of persister cells remains elusive. Using mesenchymal cell lines derived from biopsies of patients who progressed on EGFR TKI as surrogates for persister populations, we performed whole-genome CRISPR screening and identified FGFR1 as the top target promoting survival of mesenchymal EGFR mutant cancers. Although numerous previous reports of FGFR signaling contributing to EGFR TKI resistance in vitro exist, the data has not yet been sufficiently compelling to instigate a clinical trial testing this hypothesis, nor has the role of FGFR in promoting the survival of persister cells been elucidated. In this study, we find that combining EGFR and FGFR inhibitors inhibited the survival and expansion of EGFR mutant drug tolerant cells over long time periods, preventing the development of fully resistant cancers in multiple vitro models and in vivo. These results suggest that dual EGFR and FGFR blockade may be a promising clinical strategy for both preventing and overcoming EMT-associated acquired drug resistance and provide motivation for clinical study of combined EGFR and FGFR inhibition in EGFR-mutated NSCLCs.

Abstract A142: Targeting FGFR to overcome EMT-related resistance in EGFR-mutated non-small cell lung cancer

Epithelial-to-mesenchymal transition (EMT) has been identified as a mechanism of both adaptive and acquired resistance to EGFR tyrosine kinase inhibitors (TKIs) in in vitro models and clinical samples of EGFR-mutated non-small cell lung cancer (NSCLC). However, a therapeutic strategy for targeting this mechanism remains unknown. In the setting of adaptive resistance early in the course of EGFR treatment, we observed that FGFR3 upregulation coincided with increased expression of mesenchymal genes, and a pooled shRNA dropout screen identified FGFR3 as a top sensitizer to EGFR inhibitor treatment. Dual FGFR (BGJ398) and EGFR (gefitinib) inhibition suppressed the outgrowth of drug-tolerant persister clones compared to EGFR TKI alone in vitro. Finally, we observed that the combination of BGJ398 and gefitinib prevented the development of in vivo resistance in PC9 xenograft mouse models. These results suggest that dual FGFR-EGFR blockade may be an effective strategy for preventing resistance associated with EMT in EGFR mutant NSCLC.

Citation Format: Sana Raoof, David Ruddy, Daria Timonia, Leah Damon, Jeff Engelman, Aaron Hata. Targeting FGFR to overcome EMT-related resistance in EGFR-mutated non-small cell lung cancer [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2017 Oct 26-30; Philadelphia, PA. Philadelphia (PA): AACR; Mol Cancer Ther 2018;17(1 Suppl):Abstract nr A142.

Abstract A13: Development of a drug response assessment platform for biopsy-derived tumor models

Our labs have previously described a pharmacogenomic approach to identify therapeutic strategies in cancer cells derived directly from the biopsies of patients. These findings were made in pure cancer cell populations derived on the order of months. Our ultimate goal is to utilize one's own cancer cells for a personalized in vitro diagnostic test. Therefore, we aimed to develop a reliable method to analyze a high-throughput pharmacological screen in mixed cell populations with minimal cancer cells since this is the reality of fresh samples within weeks of the biopsy. The necessity for this is two-fold: first, the culture of patient biopsies is more successful on an irradiated fibroblast feeder layer and, second, noncancerous patient cells, including stromal fibroblasts, often survive biopsy culture. We identified a cocktail of two monoclonal antibodies, one against cytokeratin 8 and another against cytokeratin 18, as a consistent identifier of lung cancer cells that could be used in a high-throughput immunofluorescence-based assay. Drug sensitivity experiments with the immunofluorescence-based assay on patient-derived lung cancer cells mixed with feeder or stromal fibroblasts produced dose-response curves consistent with a pure cancer cell viability assay. We plan to utilize this assay to test the accuracy of patient-derived tumor models, obtained within weeks of biopsy, in mimicking patients' responses to targeted therapy. Ultimately, we hope this approach could help determine therapeutic choices for individual patients.

Citation Format: David P. Kodack, Matthew Held, Leah Damon, Dana Lee, Melissa Parks, Richard Dicecca, Max Greenberg, Jeffrey A. Engelman, Cyril H. Benes. Development of a drug response assessment platform for biopsy-derived tumor models. [abstract]. In: Proceedings of the AACR Special Conference: Patient-Derived Cancer Models: Present and Future Applications from Basic Science to the Clinic; Feb 11-14, 2016; New Orleans, LA. Philadelphia (PA): AACR; Clin Cancer Res 2016;22(16_Suppl):Abstract nr A13.

Proteinuria in metastatic pheochromocytoma is associated with an increased risk of Acute Respiratory Distress Syndrome, spontaneously or after therapy with 131I-meta-iodobenzylguanidine (131I-MIBG)

Acute Respiratory Distress Syndrome (ARDS) has been reported rarely in pheochromocytoma, occurring spontaneously or after therapy with 131I-meta-iodobenzylguanidine (131I-MIBG). Our objective was to determine whether proteinuria is associated with an increased risk of ARDS. This was a retrospective analysis of a prospective cohort study of 64 patients with metastatic pheochromocytoma or paraganglioma treated with 131I-MIBG on institutional protocols. Proteinuria was defined as at least one urinalysis positive for at least trace protein within 1 month prior to 131I-MIBG or within 1 month prior to spontaneous ARDS. Proportions were compared using Fisher's exact test. Urinalyses within the defined time period were available for 48 patients, 8 of whom had proteinuria. Of the 8 patients with proteinuria, 5 developed ARDS: 3 within 10 days following 131I-MIBG, two 6 months following 131I-MIBG. Both patients who developed ARDS 6 months after 131I-MIBG had proteinuria within 1 month before apparently spontaneous ARDS. None of the 40 patients whose urinalyses were all negative for protein developed ARDS. None of the 16 patients with missing urinalyses developed ARDS. Patients with antecedent proteinuria were more likely to develop ARDS than those without proteinuria (63% vs. 0%; p<0.0001). The following variables were not significantly associated with ARDS: 131I-MIBG activities administered, number of 131I-MIBG administrations, age, hypertension, or secretion of catecholamines or metanephrines. In patients with metastatic pheochromocytoma or paraganglioma, proteinuria is associated with ARDS and urine protein should be examined prior to administering 131I-MIBG.

Impact of intensive stem cell mobilization therapy on outcomes following autologous stem cell transplantation (ASCT) for non- Hodgkin lymphoma (NHL)

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Background: We retrospectively evaluated the impact of intense [I] stem cell mobilization therapy on event-free survival [EFS] and overall survival [OS] following ASCT for NHL. Methods: 80 patients (pt) were studied (2 Burkitt, 3 primary CNS, 3 follicular, 2 intravascular, 43 large cell, 12 mantle cell, 9 transformed, and 6 peripheral T-cell). Patients with very-high risk features (LDH > 500 IU/L, first remissions < 1 year, 2 or more extra-nodal sites, and/or primary CNS/intravascular/mantle cell/peripheral T-cell histology) were prospectively allocated to I stem cell mobilization (requiring hospitalization) with either cyclophosphamide [C] (6 g/m2) + etoposide [E] (2g/m2) + filgrastim [G-CSF] (±rituximab [R]) (n=5) or with cytarabine [A] (2 g/m2 bid for 8 doses) + E (40 mg/kg) + G- CSF (±R) (n=45). 30 pt were mobilized (outpatient) with C 4g/m2 + G-CSF ±R (non-intense [NI] mobilization). 76 pt received ASCT conditioning with carmustine [B] + E and C (CBV) and 2 with B + E + A and melphalan (BEAM); 2 pt did not undergo ASCT. Results: The median age was 54 (21–69 years [yr]) and 57% had an elevated LDH at presentation. 39 pt (49%) were primary induction failures (PIF). At NHL presentation, 38% were IPI high-intermediate or high risk. There were 3 non-relapse mortalities (4%): (2) B pneumonitis and (1) multi-organ failure (all following ASCT). With a median follow-up of 1.8 yr (0.1–6.4), the overall median EFS is 3 yr (48% [34–62] at 4 yr) and the median OS is 4.7 yr (59% [43–72] at 4 yr). Patients receiving I mobilization were similar to those receiving NI mobilization in terms of the # of prior therapies (median 2, each), the presenting IPI risk score, and the percent PIF (57% vs 41%; p=0.17). There were trends favoring I mobilization for both 4 yr EFS (58% [41–75] vs 35% [13–57]) and OS (66% [48–84] vs 52% [32–72]), neither statistically significant. In the sub-group of large B-cell NHL, 4 yr EFS was the same in pt receiving I mobilization (81% [63–98] vs 73% [50–96]; p=0.33) but OS was better (91% [79–100] vs 58% [35–82]; p=0.02). Conclusions: I stem cell mobilization therapy, compared to NI mobilization therapy, may improve outcomes for NHL pt with very-high risk features and may overcome the anticipated poor prognosis of these pt.

No significant financial relationships to disclose.

Treatment of primary CNS lymphoma with induction high-dose methotrexate, temozolomide, rituximab followed by consolidation cytarabine/etoposide: A pilot study with biomarker analysis

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Background: There is currently no consensus on the optimal treatment for patients diagnosed with primary CNS lymphoma (PCNSL). Between 2001–2004, UCSF PCNSL patients were treated with combination high-dose methotrexate, temozolomide, rituximab (MTR) as induction therapy. Patients in CR with this regimen were treated with high-dose cytarabine plus etoposide as consolidation. The purposes of this study were: (1) Pilot analysis to determine the safety and efficacy of intensive methotrexate-based induction therapy followed by high-dose consolidation with elimination of whole brain irradiation; (2) Analysis of molecular markers in PCNSL which predict sensitivity to chemotherapy and outcome. Methods: 21 untreated, CD20 +, immunocompetent PCNSL patients were treated with combination methotrexate (8 gm/m²), temozolomide (150 mg/m²/day)and rituximab (375 mg/m²). Patients in CR received consolidation cytarabine (2 g/ m² x 8 doses) plus etoposide (40 mg/kg over 96 hours). IHC analysis of potential biomarkers predictive of outcome was performed on paraffin sections from these patients. Candidate markers for validation were selected by gene expression analysis of an independent, multicenter dataset of 20 cases. Results: Mean age was 58.6 y (range 40–81). Median KPS was 60. MTR and cytarabine/etoposide consolidation was well-tolerated with no treatment-related mortality or evidence for neurotoxicity. One case of post-remission cytopenia occurred after consolidation and resolved spontaneously. Eleven patients (52.4%) attained CR with induction; eight received consolidation; three patients in CR deferred consolidation. Median PFS was 11.5 months. Median OS for all 21 patients has not yet been reached with median follow-up of 27.5 months. Expression of the apoptotic regulator DAP-1 by lymphoma cells as determined by IHC was associated with improved PFS (p<0.028) and OS (p<0.021). Conclusions: Combination MTR followed by intensive consolidation appears to be well tolerated in PCNSL. PFS appears at least similar to regimens that contain whole brain irradiation. A larger phase II study has been initiated to evaluate this regimen in a multicenter setting.

[Table: see text]

Secondary acute leukemia following mitoxantrone-based high-dose chemotherapy for primary breast cancer patients

The incidence of secondary myelodysplasia/acute myeloid leukemia (AML) was retrospectively assessed in an international joint study in 305 node-positive breast cancer patients, who received mitoxantrone-based high-dose chemotherapy (HDCT) followed by autologous stem cell support as adjuvant therapy. The median age of the patients was 57 years (range 22-67). In all, 268 patients received peripheral blood stem cells, and 47 patients received autologous bone marrow. After a median follow-up of 57 months (range 10-125), three cases of secondary AML (sAML) were observed, resulting in a cumulative incidence of 0.94%. One case of sAML developed 18 months after HDCT (FAB M3) The karyotype was translocation 15;17 and, after induction therapy, the patient underwent autologous stem cell transplantation, and is in complete remission (CR) of both breast cancer and AML. The second patient developed AML (FAB M4eo with inversion 16) 5 months after HDCT. This patient achieved CR after induction therapy, but died of infectious complication. A third patient developed AML (FAB M4) 6 months after HDCT. She achieved CR after induction therapy, but relapsed and expired 28 months after diagnosis of AML. sAML after mitoxantrone-based HDCT is a possible, but rare complication in breast cancer patients.

A case of factitious aplastic anemia

OBJECTIVE

We report the case of factitiously induced aplastic anemia by the ingestion of busulfan, a bifunctional alkylating chemotherapeutic agent used in the treatment of chronic myelogenous leukemia. The medical consequences and financial costs of this illness are reported. The reader will gain an understanding of the relevant clues to the diagnosis of a factitious hematologic illness, the psychodynamic issues present in this case and the legal, ethical and countertransferential issues raised by the case.

METHOD

A single case review including medical and billing records, patient and staff interviews and literature review.

RESULTS

The covert ingestion of busulfan by this patient resulted in life-threatening bone marrow suppression, bilateral aseptic hip necrosis, transfusion-dependent thrombocytopenia and a chronic pain syndrome. Her treatment was complicated by noncompliance with prescribed treatments and polymicrobial sepsis possibly secondary to the self-injection of feces into her central line. To date, the total cost of care for the treatment of this patient's medical complications secondary to her ingestion of busulfan exceeds $1,100,000.00.

CONCLUSIONS

This case underscores the importance of the early recognition by the primary care physician of the possibility of a factitious etiology of hematologic abnormalities such as aplastic anemia due to the ingestion of bone marrow ablative medications. The index of suspicion is increased when the patient is a young health care provider, usually female, with atypical pancytopenia and an unusual disease course and response to treatment.

The Trauma Symptom Checklist for Young Children (TSCYC): reliability and association with abuse exposure in a multi-site study

OBJECTIVE

The Trauma Symptom Checklist for Young Children (TSCYC) is a 90-item caretaker-report measure of children's trauma- and abuse-related symptomatology. It contains two reporter validity scales and eight clinical scales [Post-traumatic Stress-Intrusion (PTS-I), Post-traumatic Stress-Avoidance (PTS-AV), Post-traumatic Stress-Arousal (PTS-AR), Post-traumatic Stress-Total (PTS-TOT), Sexual Concerns (SC), Dissociation (DIS), Anxiety (ANX), Depression (DEP), and Anger/Aggression (ANG)], as well as an item assessing hours per week of caretaker contact with the child. This paper introduces the TSCYC and describes its psychometric properties in a multisite validity study.

METHOD

A total of 219 TSCYCs administered by six clinician/researchers across the United States were analyzed for scale reliability and association with several types of childhood maltreatment.

RESULTS

The TSCYC clinical scales have good reliability and are associated with exposure to childhood sexual abuse, physical abuse, and witnessing domestic violence. The PTS-I, PTS-AV, PTS-AR, and PTS-TOT scales were most predictive, followed by SC in the case of sexual abuse and DIS in the case of physical abuse. There were a small number of age, sex, and race effects on TSCYC scores.

CONCLUSIONS

The TSCYC appears to have reasonable psychometric characteristics, and correlates as expected with various types of trauma exposure. Subject to continued validation and the development of general population norms, its use as a clinical measure is supported.

Child Sexual Behavior Inventory: normative, psychiatric, and sexual abuse comparisons

A normative sample of 1,114 children was contrasted with a sample of 620 sexually abused children and 577 psychiatric outpatients on the Child Sexual Behavior Inventory (CSBI), a 38-item behavior checklist assessing sexual behavior in children 2 to 12 years old. The CSBI total score and each individual item differed significantly between the three groups after controlling for age, sex, maternal education, and family income. Sexually abused children exhibited a greater frequency of sexual behaviors than either the normative or psychiatric outpatient samples. Test-retest reliability and interitem correlation were satisfactory. Sexual behavior problems were related to other generic behavior problems. This contributed to the reduced discrimination between psychiatric outpatients and sexually abused children when compared to the normative/sexually abused discrimination.

A randomized trial of high- vs standard-dose mitoxantrone with cytarabine in elderly patients with acute myeloid leukemia

To evaluate the efficacy and tolerability of a high-dose mitoxantrone-based induction regimen without consolidation therapy in patients over age 60 with newly diagnosed acute myeloid leukemia (AML), 54 patients aged 60-83 were randomized to receive mitoxantrone, either 80 mg/m2 on day 2, or 12 mg/m2 on days 1-3 in addition to cytarabine, 3 g/m2 on days 1-5. Significant toxicity included mucositis, diarrhea, transient hyperbilirubinemia and cardiac events. No difference in toxicity was observed between the two dosage regimens. Overall, 27 patients achieved a complete remission (CR), 16/28 CR in the high-dose and 11/25 in the lower-dose group. Induction death occurred in 11 patients, three in the high-dose and eight in the low-dose arm. Actuarial median survival was 6 months for the low-dose and 9 months for the high-dose group, and the respective relapse-free survival is 3 and 5 months. The observed differences in outcome were not statistically significant. patients in both arms of this trial, who received no consolidation, appear to have response and survival rates equivalent to those of standard-dose induction with repetitive consolidation. This approach might offer elderly patients equivalent outcome with fewer days of treatment, presumably enhancing quality of life.

Unreliability of the abdominal fat pad biopsy in the evaluation of nephrosis: report of 3 consecutive cases

In the workup of unexplained nephrotic syndrome in the elderly patient, renal biopsy has shown amyloidosis to be the cause in 15-30% of the cases. Most of the cases of amyloidosis are primary and are, therefore, treatable with alkylating agents, albeit at a high level of toxicity. Abdominal fad pad biopsy has been suggested as a minimally invasive, low-cost method for diagnosing amyloidosis that is 100% specific. We report our experience with 3 consecutive cases of fat pad biopsy in the workup of unexplained nephrosis in the elderly patient: including the first false positive reported with respect to nephrotic renal disease, a false negative, and a true positive. We feel that in an elderly patient with unexplained nephrosis though the abdominal fat pad biopsy may be helpful, the patient should not be committed to a regimen with potentially very high toxicity on the basis of a positive fat pad biopsy alone. We recommend that the more invasive renal biopsy be performed should therapy with alkylating agents be contemplated.