Enhanced efficacy of mesothelin-targeted immunotoxin LMB-100 and anti-PD-1 antibody in patients with mesothelioma and mouse tumor models

LMB-100 is an immunotoxin targeting the cell surface protein mesothelin, which is highly expressed in many cancers including mesothelioma. Having observed that patients receiving pembrolizumab off protocol after LMB-100 treatment had increased tumor responses; we characterized these responses and developed animal models to study whether LMB-100 made tumors more responsive to antibodies blocking programmed cell death protein 1 (PD-1). The overall objective tumor response in the 10 patients who received PD-1 inhibitor (pembrolizumab, 9; nivolumab, 1) after progression on LMB-100 was 40%, and the median overall survival was 11.9 months. Of the seven evaluable patients, four had objective tumor responses, including one complete response and three partial responses, and the overall survival for these patients was 39.0+, 27.7, 32.6+, and 13.8 months. When stratified with regard to programmed death ligand 1 (PD-L1) expression, four of five patients with tumor PD-L1 expression had objective tumor response. Patients with positive tumor PD-L1 expression also had increased progression-free survival (11.3 versus 2.1 months, P = 0.0018) compared with those lacking PD-L1 expression. There was no statistically significant difference in overall survival (27.7 versus 6.8 months, P = 0.1). LMB-100 caused a systemic inflammatory response and recruitment of CD8⁺ T cells in patients' tumors. The enhanced antitumor effects with LMB-100 plus anti-PD-1 antibody were also observed in a human peripheral blood mononuclear cell-engrafted mesothelioma mouse model and a human mesothelin-expressing syngeneic lung adenocarcinoma mouse model. LMB-100 plus pembrolizumab is now being evaluated in a prospective clinical trial for patients with mesothelioma.

POS1276 LONG TERM OUTCOME OF MULTIPLE ULTRASOUND GUIDED SUPRASCAPULAR NERVE BLOCK IN TREATMENT OF FROZEN SHOULDER IN DIABETIC PATIENTS

Background:

Frozen shoulder is prevalent among diabetic patients, and usually has aggressive course, with more tendency to be bilateral and resistant to treatment. Suprascapular nerve block (SSNB) is used with increasing frequency by anesthetists and rheumatologists in the management of frozen shoulder. We previously introduced a protocol of nine injections for SSNB with better short term outcome than single SSNB injection (1). Long term outcome of SSNB in management of frozen shoulder is still not detected.

Objectives:

To evaluate the long term effect of multiple (nine) ultrasound guided supra-scapular nerve block in treatment of diabetic frozen shoulder.

Methods:

A retrospective cohort study followed up 40 diabetic patients who received a course of ultrasound guided multiple supra-scapular nerve block (9 injections) on 2014. In this study we retrospectively assessed the patients from previously recorded data at a mean duration of 6 years after completing the 9 injection course SSNB clinically by measuring the shoulder active range of motion (using a goniometer in three planes: abduction, internal, and external rotation). Visual analogue scale and Functional assessment by shoulder pain and disability index (SPADI).

Results:

Thirty four patients (85% of original cohort) completed the long term follow up.

The patients were 19 (55.9%) females, 60.6 y mean age, and the mean of disease duration was 85.6 months. The majority of patients (33 patients 97.05%) continues improvement and gained within normal complete range of motions in all directions and excellent grades of shoulder function (Table 1).

Table 1.Clinical ParametersAt base lineAt 4 monthsLast follow up at (72months±4)**P valueSPADI pain score (100)(68.8 ± 0.5)a(10.3 ± 7.4)b(0.9±1.9)c0.00*SPADI disability score (100)(69.2 ± 7.7)a(6.25 ± 2.25)b(0.4±0.8)c0.00*SPADI total (100)(69.1 ± 8.5)a(8.15 ± 5.4)b(1.1±0.9)c0.00*Patient global assessment (100)(90.2 ± 8.2)a(8.2 ± 4.2)b(0.4±2.1)c0.00*Night pain (100)(55.4±10.2)a(10.3 ± 4.9)b(2.3±1.1)c0.00*Abduction (180°)(77.5 ± 4.7)a(170.3 ± 10.3)b(174.2±6.2)b0.00*External rotation (100 °)(46 ± 12.6)a(80.1 ± 10.2)b(86.4±10.3)b0.00*Internal rotation (70 °)(34.5 ± 2.4)a(55.4 ± 10.1)b(60.2±9.5)b0.00*

* P <0.05 there was a statistical significant difference

•A,b,c--- the alphabet of different symbols ---means a significant statistical difference between groups

SPADI: shoulder pain and disability index

Conclusion:

The multiple injection courses for supra-scapular nerve block has an excellent long term efficacy as treatment of diabetic frozen shoulder. This method should be the treatment of choice in patients of diabetic frozen shoulder who do not respond to physiotherapy.

References:

[1]Mortada, M. A., Ezzeldin, N., Abbas, S. F., Ammar, H. A. & Salama, N. A. Multiple versus single ultrasound guided suprascapular nerve block in treatment of frozen shoulder in diabetic patients. J. Back Musculoskelet. Rehabil. 30, 537–542 (2017).

Disclosure of Interests:

None declared

Phase I study of mesothelin-targeted immunotoxin LMB-100 in combination with tofacitinib in patients with advanced pancreatobiliary cancer

3051

Background: LMB-100 recombinant immunotoxin consists of a mesothelin-binding Fab for targeting a modified Pseudomonas exotoxin A payload to tumors. Previous clinical trials demonstrated that almost all patients formed anti-drug-antibodies (ADAs) to LMB-100 that made administration beyond cycle 2 ineffective. Tofacitinib is an oral JAK inhibitor that prevented formation of ADAs against a closely related immunotoxin in pre-clinical studies. The primary objective of the dose escalation cohort was assessment of safety and tolerability of LMB-100 given with tofacitinib to patients with mesothelin-expressing solid tumors. The primary objective of the expansion cohort was to determine whether co-administration of tofacitinib delays formation of neutralizing LMB-100 ADAs. Methods: Patients (n = 13) with pancreatic adenocarcinoma and other mesothelin-expressing solid tumors (n = 3; cholangiocarcinoma, appendix, cystadenocarcinoma) were treated for up to 3 cycles with LMB-100 as a 30-minute infusion on days 4, 6, and 8 at two dose levels (100 and 140 mcg/kg) and co-treated with oral tofacitinib for the first 10 days of the cycle (10 mg BID). Results: Dose level 1 of LMB-100 was started at 100 mcg/kg one dose level below the single agent MTD. Dose escalation to 140 mcg/kg (dose level 2) resulted in DLTs in 2 of the 3 patients treated: grade 3 cardiac toxicity and grade 4 hyponatremia, both attributed to capillary leak syndrome. Ultimately, 7 patients were treated at dose level 1 without DLTs and 100 mcg/kg was chosen as the LMB-100 dose for the expansion cohort. The last of 6 patients treated in the expansion cohort developed grade 4 pericardial effusion leading to early closure of the study for toxicity. No objective responses were seen. Of the 8 patients who received two cycles of treatment at MTD, 4 met prespecified criteria for ADA prevention, and 2 patients who went on to receive cycle 3 had detectable LMB-100 plasma drug levels after administration. Conclusions: LMB-100 was unable to be co-administered safely with tofacitinib. ADA formation was prevented in 2 patients through 3 cycles, a rare occurrence. Clinical trial information: NCT04034238.

In Vitro and In Vivo Comparison of 3,2-HOPO Versus Deferoxamine-Based Chelation of Zirconium-89 to the Antimesothelin Antibody Anetumab

Introduction: [²²⁷Th]Th-3,2-HOPO-MSLN-mAb, a mesothelin (MSLN)-targeted thorium-227 therapeutic conjugate, is currently in phase I clinical trial; however, direct PET imaging using this conjugate is technically challenging. Thus, using the same MSLN antibody, we synthesized 3,2-HOPO and deferoxamine (DFO)-based zirconium-89 antibody conjugates, [⁸⁹Zr]Zr-3,2-HOPO-MSLN-mAb and [⁸⁹Zr]Zr-DFO-MSLN-mAb, respectively, and compared them in vitro and in vivo.

Methods: [⁸⁹Zr]Zr-3,2-HOPO-MSLN-mAb and [⁸⁹Zr]Zr-DFO-MSLN-mAb were evaluated in vitro to determine binding affinity and immunoreactivity in HT29-MSLN and PDX (NCI-Meso16, NCI-Meso21) cells. For both the zirconium-89 conjugates, in vivo studies (biodistribution/imaging) were performed at days 1, 3, and 6, from which tissue uptake was determined.

Results: Both the conjugates demonstrated a low nanomolar binding affinity for MSLN and >95% immunoreactivity. In all the three tumor types, biodistribution of [⁸⁹Zr]Zr-DFO-MSLN-mAb resulted in higher tumor uptake(15.88-28-33%ID/g) at all time points compared with [⁸⁹Zr]Zr-3,2-HOPO-MSLN-mAb(7–13.07%ID/g). [⁸⁹Zr]Zr-3,2-HOPO-MSLN-mAb femur uptake was always higher than [⁸⁹Zr]Zr-DFO-MSLN-mAb, and imaging results concurred with the biodistribution studies.

Conclusions: Even though the conjugates exhibited a high binding affinity for MSLN, [⁸⁹Zr]Zr-DFO-MSLN-mAb showed a higher tumor and lower femur uptake than [⁸⁹Zr]Zr-3,2-HOPO-MSLN-mAb. Nevertheless, [⁸⁹Zr]Zr-3,2-HOPO-MSLN-mAb could be used to study organ distribution and lesion uptake with the caveat of detecting MSLN-positive bone lesions. Clinical trial (NCT03507452).

Malignant mesothelioma: Advances in immune checkpoint inhibitor and mesothelin-targeted therapies

Malignant mesothelioma is an aggressive cancer with a poor prognosis and limited treatment options. For many years, the only US Food and Drug Administration-approved first-line treatment for unresectable mesothelioma was pemetrexed plus cisplatin. However, the recent approval of nivolumab plus ipilimumab as frontline treatment for patients with pleural mesothelioma marks a significant milestone for the treatment of this disease. In this review, the authors describe recent advances in therapeutic strategies for the treatment of patients with advanced, unresectable mesothelioma, highlighting the emerging use of immunotherapy and mesothelin-targeted therapies for the management of malignant mesothelioma.

Emergency Laparotomy in a COVID-19 patient with acute abdomen

We describe here the first laparotomy involving a COVID-19 patient in Malaysia. A 60-year-old man screened positive for SARS-CoV-2 in March 2020 and developed acute abdomen in the ward in Hospital Sultanah Bahiyah, Kedah. He underwent laparotomy and cholecystectomy for gangrenous cholecystitis. All personnel adhered to infectious control precautions, donning full personal protective equipment (PPE) throughout the surgery. Post-operatively, due to raised septic parameters, he was carefully diagnosed with and treated empirically for superimposed bacterial sepsis instead of cytokine release syndrome, with confirmed blood culture of Klebsiella pneumoniae. Patient was discharged well later. None of the staff involved in his care developed COVID-19 infection.

Phase I study of mesothelin-targeted immunotoxin LMB-100 in combination with tofacitinib in persons with pancreatobiliary cancer or other mesothelin expressing solid tumors

TPS452

Background: LMB-100 recombinant immunotoxin consists of a mesothelin-binding Fab for targeting with a modified Pseudomonas exotoxin A payload. Formation of anti-drug antibodies (ADAs) is thought to contribute significantly to limited clinical efficacy of LMB-100 seen in prior clinical trials. Most patients develop clinically meaningful ADAs after 1-2 cycles of LMB-100, resulting in rapid neutralization of LMB-100 during subsequent cycles and undetectable plasma drug levels. Tofacitinib is an oral Janus Kinase-1 and -3 (JAK) inhibitor approved by the FDA for the treatment of rheumatoid arthritis and ulcerative colitis. Pre-clinical studies have shown that tofacitinib can prevent the formation of ADAs against recombinant immunotoxin (Onda et al. Journal of Immunology 2014), and that co-administration of tofacitinib with LMB-100 increases immunotoxin serum half- life in mice and anti-tumor efficacy (Simon et al. JCI Insight 2019). We hypothesize that co-administration of tofacitinib with LMB-100 will prevent or delay the formation of high titer ADAs to LMB-100, such that 2 effective cycles of immunotoxin can be administered to patients. Methods: This phase I clinical trial consists of a dose escalation phase using 3+3 design to determine the maximum tolerated dose (MTD) of LMB-100 that can be administered with tofacitinib in participants (n = 18 max) with mesothelin-expressing solid tumors, followed by a dose expansion phase at the MTD for participants (n = 15) with pancreatic adenocarcinoma or extrahepatic cholangiocarcinoma. The primary objective of the expansion phase is to determine whether co-administration of tofacitinib delays formation of neutralizing anti-LMB-100 ADAs for cycle 2 of treatment as measured by LMB-100 plasma drug levels. A positive outcome will be reached if percent of participants achieving threshold LMB-100 drug levels during cycle 2 increases from 50% to 80% (83.6% probability if >10 of 15 evaluable participants meet this milestone). Plasma drug levels during cycle 3 will also be analyzed as a secondary endpoint. Key inclusion criteria include adults with histologically confirmed previously treated solid tumor malignancies. Participants will receive tofacitinib 10 mg twice daily on days 1-10 and LMB-100 at 65, 100, or 140 mcg/kg on days 4, 6 and 8 of a 21-day cycle. The dose escalation phase has been completed and enrollment onto dose expansion phase is ongoing. Clinical trial information: NCT04034238.

UHRF1 Is a Novel Druggable Epigenetic Target in Malignant Pleural Mesothelioma

INTRODUCTION

Ubiquitin-like with plant homeodomain and ring finger domains 1 (UHRF1) encodes a master regulator of DNA methylation that has emerged as an epigenetic driver in human cancers. To date, no studies have evaluated UHRF1 expression in malignant pleural mesothelioma (MPM). This study was undertaken to explore the therapeutic potential of targeting UHRF1 in MPM.

METHODS

Microarray, real-time quantitative reverse transcription-polymerase chain reaction, immunoblot, and immunohistochemistry techniques were used to evaluate UHRF1 expression in normal mesothelial cells (NMCs) cultured with or without asbestos, MPM lines, normal pleura, and primary MPM specimens. The impact of UHRF1 expression on MPM patient survival was evaluated using two independent databases. RNA-sequencing, proliferation, invasion, and colony formation assays, and murine xenograft experiments were performed to evaluate gene expression and growth of MPM cells after biochemical or pharmacologic inhibition of UHRF1 expression.

RESULTS

UHRF1 expression was significantly higher in MPM lines and specimens relative to NMC and normal pleura. Asbestos induced UHRF1 expression in NMC. The overexpression of UHRF1 was associated with decreased overall survival in patients with MPM. UHRF1 knockdown reversed genomewide DNA hypomethylation, and inhibited proliferation, invasion, and clonogenicity of MPM cells, and growth of MPM xenografts. These effects were phenocopied by the repurposed chemotherapeutic agent, mithramycin. Biochemical or pharmacologic up-regulation of p53 significantly reduced UHRF1 expression in MPM cells. RNA-sequencing experiments exhibited the pleiotropic effects of UHRF1 down-regulation and identified novel, clinically relevant biomarkers of UHRF1 expression in MPM.

CONCLUSIONS

UHRF1 is an epigenetic driver in MPM. These findings support the efforts to target UHRF1 expression or activity for mesothelioma therapy.

Clinical implications of conventional cytogenetics, fluorescence in situ hybridization (FISH) and molecular testing in chronic myeloid leukaemia patients in the tyrosine kinase inhibitor era - A review

Chronic myeloid leukaemia (CML) provides an illustrative disease model for both molecular pathogenesis of cancer and rational drug therapy. Imatinib mesylate (IM), a BCR-ABL1 targeted tyrosine kinase inhibitor (TKI) drug, is the first line gold standard drug for CML treatment. Conventional cytogenetic analysis (CCA) can identify the standard and variant Philadelphia (Ph) chromosome, and any additional complex chromosome abnormalities at diagnosis as well as during treatment course. Fluorescence in situ hybridization (FISH) is especially important for cells of CML patients with inadequate or inferior quality metaphases or those with variant Ph translocations. CCA in conjunction with FISH can serve as powerful tools in all phases of CML including the diagnosis, prognosis, risk stratification and monitoring of cytogenetic responses to treatment. Molecular techniques such as reverse transcriptase-polymerase chain reaction (RT-PCR) is used for the detection of BCR-ABL1 transcripts at diagnosis whereas quantitative reverse transcriptase-polymerase chain reaction (qRTPCR) is used at the time of diagnosis as well as during TKI therapy for the quantitation of BCR-ABL1 transcripts to evaluate the molecular response and minimal residual disease (MRD). Despite the excellent treatment results obtained after the introduction of TKI drugs, especially Imatinib mesylate (IM), resistance to TKIs develops in approximately 35% - 40% of CML patients on TKI therapy. Since point mutations in BCR-ABL1 are a common cause of IM resistance, mutation analysis is important in IM resistant patients. Mutations are reliably detected by nested PCR amplification of the translocated ABL1 kinase domain followed by direct sequencing of the entire amplified kinase domain. The objective of this review is to highlight the importance of regular and timely CCA, FISH analysis and molecular testing in the diagnosis, prognosis, assessment of therapeutic efficacy, evaluation of MRD and in the detection of BCR-ABL1 kinase mutations which cause therapeutic resistance in adult CML patients.

AB0177 RHEUMATOID ARTHRITIS SAUDI DATABASE (RASD): A SINGLE CENTER EXPERIENCE

Background:

National Registries are essential to direct current practice and design appropriate management strategies1. Rheumatoid arthritis (RA) registries in the middle east and north Africa remain scarcely represented2.

Objectives:

Our objective is to describe the Saudi RA population and to compare the findings to internationally reported data.

Methods:

This is a cross sectional, analytical study that was conducted at Doctor Soliman Fakeeh Hospital (DSFH). The study ran from December of 2014 and concluded in December of 2018 using a pool of 433 patients. Inclusion criteria included adults older than 18 years of age who fulfilled the 2010 American College of Rheumatology criteria for diagnosis of RA3. Data were collected from patients and entered in a specially designed program for this registry. They included main demographic details,, lag times to final disease diagnosis. Disease Activity Score-28-C Reactive Protein (DAS-28-CRP) was calculated on presentation and on subsequent visits with intervals ranging from three to six months between them. Multiple regression model was used to assess the predictors of disease activity. We charted the lines of medications given, including conventional and biologic disease modifying antirheumatic drugs (DMARDs), following treat to target strategies4.

Results:

Out of 430 patients, 76.68% were female, while only 23.32% were male and the mean age was found to be 49.26 years with SD±11.

At initial presentation, 45.5% had demonstrated active disease (moderate or high disease activity) based on DAS-28-CRP scores while 54.5% were in remission or low disease activity. Out of the total number of clinic visitors, 330 had regular follow ups for more than 1 year while 103 patients were either irregularly visiting the rheumatology clinic or had lost follow up. The remission rates after 1 year had increased to 79.7% (263 patients), while 9.7% (32 patients) had low disease activity and no patients had sustained high disease activity at the end of follow up. It was also found that the female gender, higher Health Assessment Questionnaire-Disability Index (HAQ-DI) and a longer lag1/lag2 period were associated with higher disease activity in our population. Biologic medications had been used by 129 patients (29.7%) while conventional DMARDs were given to 304 patients (70.3%).

Conclusion:

We described a population of RA patients in a single center in SA. We detected higher remission rates at one year of follow up. This could be attributed to many factors, including good referral systems and treat to target strategies with easier access to biologic medications.

References:

[1]Singh JA, Saag KG, Bridges SL Jr, Akl EA, Bannuru RR, Sullivan MC, Vaysbrot E, McNaughton C, Osani M, Shmerling RH, Curtis JR, Furst DE, Parks D, Kavanaugh A, O’Dell J, King C, Leong A, Matteson EL, Schousboe JT, Drevlow B, Ginsberg S, Grober J, St Clair EW, Tindall E, Miller AS, McAlindon T. 2015 American College of Rheumatology Guideline for the Treatment of Rheumatoid Arthritis.Arthritis Rheumatol.2016 Jan;68(1):1-26.

[2]Smolen, Josef S., et al. “EULAR recommendations for the management of rheumatoid arthritis with synthetic and biological disease-modifying antirheumatic drugs: 2013 update.”Annals of the rheumatic diseases73.3 (2014): 492-509.

[3]Saag KG, Teng GG, Patkar NM, Anuntiyo J, Finney C, Curtis JR, et al. American College of Rheumatology 2008 recommendations for the use of nonbiologic and biologic disease-modifying antirheumatic drugs in rheumatoid arthritis.Arthritis Rheum2008;59: 762–84.

[4]Hussain W, Noorwali A, Janoudi N. From symptoms to diagnosis: an observational study of the journey of rheumatoid arthritis patients in Saudi Arabia.Oman Med J.2016;31(1):29.

Disclosure of Interests:

Rola Hassan Grant/research support from: Pfizer pharmaceuticals, Mohamed Cheikh Grant/research support from: Pfizer pharmaceuticals, Hani Almoallim Grant/research support from: Pfizer pharmaceuticals, Hanan Faruqui Grant/research support from: Pfizer pharmaceuticals, Reem AlQuraa Grant/research support from: Pfizer pharmaceuticals, Ayman Eissa Grant/research support from: Pfizer pharmaceuticals, Aous Alhazmi Grant/research support from: Pfizer pharmaceuticals, Nahid Janoudi Grant/research support from: Pfizer pharmaceuticals

Phase II study of olaparib in malignant mesothelioma (MM) to correlate efficacy with germline and somatic mutations in DNA repair genes

9054

Background: BRCA1 associated protein 1 ( BAP1), a nuclear deubiquitinase involved in DNA double-strand break repair is frequently mutated in MM. Because poly(ADP-ribose) polymerase inhibitors (PARPIs) induce synthetic lethality in BRCA1/2 mutant cancers, we sought to evaluate efficacy of olaparib in patients with MM and correlate it with pathogenic germline and somatic mutations in DNA repair genes. Methods: Phase II single-center study (NCT03531840) enrolled patients with advanced pleural or peritoneal mesothelioma who had progressed on prior therapies, age >18 years, ECOG performance status <1, adequate organ and bone marrow function. Olaparib 300mg was given twice daily orally in 3 week cycles until disease progression or toxicity. Efficacy was assessed by CT scan every 6 weeks using RECIST criteria. Whole exome sequencing (WES) was performed on blood and tumor samples to identify pathogenic germline and somatic mutations in DNA repair genes. Primary objective was to determine response rate based on germline or somatic mutation status of DNA repair genes. Results: Between July 2018 to May 2019, 23 patients were enrolled, 15 pleural and 8 peritoneal MM [14 male; median age 63 (range 41-75 years); median number of prior treatments 3 (range 1-5)]. Median olaparib cycles received was 4 (2-21). WES to identify pathogenic mutations in the germline and tumor was performed in 23 and 17 patients respectively. Four patients had germline BAP1, 1 germline MRE11A, and 5 had somatic BAP1 mutations. Of 22 evaluable patients, 1(4%) had partial response (PR), 17 (77%) had stable disease at 6 weeks and 4 (18%) had progressive disease. Patient with PR had a germline mutation in MRE11A. Median progression free survival (PFS) and overall survival (OS) for all patients was 3.4 months (95% CI: 2.7 – 4.8 months) and 8.1 months (95% CI: 4.5 months – not estimable) respectively. Median PFS of germline BAP1 mutant patients (n = 4) was 2.3 months (95% CI: 1.3 – 3.6 months) compared to 4.1 months (95% CI: 2.7 – 5.5 months) for BAP1wild type patients (n = 18;P = 0.026). Median OS was 4.6 months (95% CI: 3.1 – 4.9 months) for patients with germline BAP1 mutation versus not reached for those without germline BAP1 mutation (P = 0.0058). The most common side effects of olaparib were anemia (16%), lymphopenia (24%), nausea (14%), and increased creatinine (9%). Conclusions: Olaparib has limited anti-tumor activity in previously treated MM patients including those with germline or somatic BAP1 mutations. Presence of germline BAP1 mutations was associated with decreased PFS and OS. Clinical trial information: NCT03531840.

Feasibility and preliminary safety and efficacy of first-in-human intraperitoneal delivery of MCY-M11, anti-human-mesothelin CAR mRNA transfected into peripheral blood mononuclear cells, for ovarian cancer and malignant peritoneal mesothelioma

3014

Background: MCY-M11 is a mesothelin-targeting chimeric antigen receptor (CAR) therapy made by a non-viral, mRNA-based platform, for rapid ( < 1 day) CAR manufacturing. We are conducting a phase I dose escalation trial in ovarian cancer and malignant peritoneal mesothelioma (MPM) (NCT03608618). Methods: MCY-M11 are fresh, non-expanded, autologous peripheral blood mononuclear cells (PBMCs) transfected by flow electroporation with mRNA encoding a human anti-mesothelin CAR. Following a 3+3 design, patients are treated in dose level (DL) escalating cohorts (DL1 1.0 x 107, DL2 5.0 x 107, DL3 1.0 x 108, DL4 5.0 x 108 cells/dose), in one cycle of weekly x 3 doses, intraperitoneal (ip) without preconditioning chemotherapy. Results: By January 2020, CP-M11-101 study successfully completed DL1 and DL2 without safety concerns. Based on 11 patients treated in DL1, DL2 and DL3, ip infusion of MCY-M11 is safe and well tolerated. No infusion-related adverse events and no dose limiting toxicities (DLTs) have occurred. No neurotoxicity has been observed. Most reported treatment-related adverse events have been Grades 1-2 per NCI CTCAE. One patient in DL3 presented with G2 pericarditis, fever and transient neutropenia clinically assessed as related SAEs, that resolved without further complications. These events were assessed as on-target off-tumor effects and possibly G1 cytokine release syndrome (CRS). Two unrelated SAEs (G2 confusion in a patient in DL2; G3 enterocutaneous fistula in a patient in DL3) were reported. These 2 patients have been replaced as they did not complete the evaluation period (3 weekly infusions and the DLT 43 day follow up). There have been no treatment-related discontinuations or deaths. Three patients in DL2 showed stable disease (SD) by RECIST 1.1 at the end of the DLT period. Of them, 1 completed the study and did not participate in additional follow up, 1 remained in SD 6 months, and 1 remained in SD 2 months. In DL3, 1 patient remains in SD at 2 months, and evaluation is pending for the other 2 patients. Enrollment is ongoing. Conclusions: Feasibility of 1-day manufacturing of MCY-M11 for ip delivery is demonstrated. Treatment has been safe. Initial SD observed in DL2 and DL3 with one-cycle infusions is encouraging and supports exploration of additional strategies such as the addition of preconditioning chemotherapy and multiple cycles to increase efficacy. Clinical trial information: NCT03608618 .

Phase I study of mesothelin-targeted immunotoxin LMB-100 given as a long infusion with or without nab-paclitaxel

3553

Background: LMB-100 recombinant immunotoxin consists of a mesothelin-binding Fab for targeting a modified Pseudomonas exotoxin A payload. Previous Phase 1 clinical testing of a 30-minute LMB-100 “short” infusion format identified a serum half-life of ~1 hour. Pre-clinical data suggested that extending infusion time could improve anti-tumor efficacy by increasing tumor cell duration of exposure to LMB-100. The primary objective of this study was to determine the safety and tolerability of administering LMB-100 in a long infusion format over 24-48 hours alone or with nab-paclitaxel chemotherapy in patients with mesothelin-expressing solid tumors. Methods: Patients (n = 15) with pancreatic adenocarcinoma and other mesothelin-expressing solid tumors (n = 3; mesothelioma, colon, and ampullary cancers) treated on 3 dose levels received long infusion of LMB-100 (65 or 100 mcg/kg/day) for 24 hour on Days 1 and 4 (n = 6) or 48 hour on Day 1 (n = 9) with or without a loading dose (40 mcg/kg over 30 minutes) for up to 2 cycles. In the second arm, patients (n = 5) with pancreatic adenocarcinoma were treated with LMB-100 over 24 hours on Day 1 concurrently with nab-paclitaxel (125 mg/m2) for up to 3 cycles. Results: DLT of proteinuria (grade 3) in one patient and acute kidney injury (grade 1) in one patient were observed amongst patients receiving 100 mcg/kg/day over 48 hours and 24 hours, respectively. No objective responses were seen but all patients receiving nab-paclitaxel had > 50% decrease in CA 19-9. Patients at all single agent dose levels (8 of 10 evaluable) developed high titer anti-drug antibodies (ADAs) against LMB-100. Those with ADAs (8 of 8) had undetectable cycle 2 peak plasma LMB-100 concentration. Development of high titer ADAs occurred more frequently with long infusion than seen previously with “short” infusion LMB-100. Most long infusion patients (19 of 20) developed increased serum IL-6 within 24 hours of LMB-100 infusion. However, the systemic inflammatory response to LMB-100 (as measured by increased serum CRP) which occurs in most “short” infusion patients was not observed. Conclusions: Long infusion format LMB-100 is generally well tolerated but immunogenicity limits treatment to 1 effective cycle. No anti-tumor efficacy of the single agent was observed. Clinical trial information: NCT02810418 .

18F-FDG PET Assessment of Malignant Pleural Mesothelioma: Total Lesion Volume and Total Lesion Glycolysis-The Central Role of Volume

Cancer survival is related to tumor volume. ¹⁸F-FDG PET measurement of tumor volume holds promise but is not yet a clinical tool. Measurements come in 2 forms: the first is total lesion volume (TLV) based on the number of voxels in the tumor, and the second is total lesion glycolysis (TLG), which is the TLV multiplied by the average SUL (i.e., SUV normalized for lean mass) of the tumor (SUL_average). In this study, we measured tumor volume in patients with malignant pleural mesothelioma (MPM). Methods: A threshold-based program in Interactive Data Language was developed to measure tumor volume in ¹⁸F-FDG PET images. Nineteen patients with MPM were studied before and after 2 cycles (6 wk) of chemoimmunotherapy. Measurements included TLV, TLG, the sum of the SULs in the tumor (SUL_total, a measure of total ¹⁸F-FDG uptake), and SUL_average Results: Baseline TLV ranged from 11 to 2,610 cm³ TLG ranged from 32 to 8,552 cm³ g/mL and correlated strongly with TLV. Although tumor volumes ranged over 3 orders of magnitude, SUL_average stayed within a narrow range of 2.4-5.3 units. Thus, TLV was the major component of TLG, whereas SUL_average was a minor component and was essentially constant. Further evaluation of SUL_average showed that in this cohort its 2 components, SUL_total and TLV, changed in parallel and were strongly correlated (r = 0.99, P < 0.01). Thus, whether the tumors were large or small, ¹⁸F-FDG uptake as measured by SUL_total was proportional to the TLV. Conclusion: TLG equals TLV multiplied by SUL_average, essentially TLV multiplied by a constant. Thus TLG, commonly considered a measure of metabolic activity in tumors, is also in this cohort a measure of tumor volume. The constancy of SUL_average is due to the fact that ¹⁸F-FDG uptake is proportional to tumor volume. Thus, in this study, ¹⁸F-FDG uptake was also a measure of volume.

Is Procalcitonin more superior to hs-CRP in the diagnosis of infection in diabetic foot ulcer?

INTRODUCTION

Procalcitonin (PCT) has recently emerged as a marker for diagnosing infection. This study aimed to compare the performance of PCT and other infection markers in diagnosing infected diabetic foot ulcer (IDFU).

MATERIALS AND METHODS

A total of 128 diabetic patients with foot ulcers were recruited and divided into two groups, consisting of 73 patients in the IDFU group and 55 in the non-infected diabetic foot ulcer (NIDFU). The severity of infection in IDFU patients was graded based on the Infectious Disease Society of America-International Working Group on the Diabetic Foot classification. Blood samples from all the patients were collected for measurement of PCT, high sensitivity C-reactive protein (hs-CRP) and white cell count (WBC). The area under the receiver operating curves (AUC) were then constructed and analysed.

RESULTS

PCT, hs-CRP and WBC levels were significantly higher in the IDFU group compared to NIDFU with hs-CRP demonstrated the highest AUC (0.91; p <0.001) followed by PCT (0.814; p < 0.001) and lastly WBC (0.775; p < 0.001). The best cut off value, sensitivity and specificity for the presence of infection in diabetic foot, were 3.47 mg/dL, 80% and 89% for hs-CRP, 0.11 ng/ml, 70% and 87% for PCT and 11.8x109/L, 60% and 90% for WBC. All the infection markers showed significant positive correlations with infection severity of DFU.

CONCLUSION

This study showed that hs-CRP is a more sensitive marker for diagnosing IDFU. Although PCT is useful in differentiating IDFU from NIDFU, the use of PCT is not necessary as it adds little value to the current practice.

First-in-Human, Multicenter, Phase I Dose-Escalation and Expansion Study of Anti-Mesothelin Antibody-Drug Conjugate Anetumab Ravtansine in Advanced or Metastatic Solid Tumors

PURPOSE

This phase I study, which to our knowledge is the first-in-human study of this kind, investigates the safety, tolerability, pharmacokinetics, and clinical activity of anetumab ravtansine, an antibody–drug conjugate of anti-mesothelin antibody linked to maytansinoid DM4, in patients with advanced, metastatic, or recurrent solid tumors known to express the tumor-differentiation antigen mesothelin.

PATIENTS AND METHODS

This phase I, open-label, multicenter, dose-escalation and dose-expansion study of anetumab ravtansine enrolled 148 adult patients with multiple solid tumor types. Ten dose-escalation cohorts of patients with advanced or metastatic solid tumors (0.15-7.5 mg/kg) received anetumab ravtansine once every 3 weeks, and 6 expansion cohorts of patients with advanced, recurrent ovarian cancer or malignant mesothelioma received anetumab ravtansine at the maximum tolerated dose once every 3 weeks, 1.8 mg/kg once per week, and 2.2 mg/kg once per week.

RESULTS

Forty-five patients were enrolled across the 10 dose-escalation cohorts. The maximum tolerated dose of anetumab ravtansine was 6.5 mg/kg once every 3 weeks or 2.2 mg/kg once per week. Thirty-two patients were enrolled in the 6.5 mg/kg once-every-3-weeks, 35 in the 1.8 mg/kg once-per-week, and 36 in the 2.2 mg/kg once-per-week expansion cohorts. The most common drug-related adverse events were fatigue, nausea, diarrhea, anorexia, vomiting, peripheral sensory neuropathy, and keratitis/keratopathy. There were no drug-related deaths. Anetumab ravtansine pharmacokinetics were dose proportional; the average half-life was 5.5 days. Among 148 patients with mesothelioma or ovarian, pancreatic, non–small-cell lung, and breast cancers, 1 had a complete response, 11 had partial responses, and 66 had stable disease. High levels of tumor mesothelin expression were detected in patients with clinical activity.

CONCLUSION

Anetumab ravtansine exhibited a manageable safety and favorable pharmacokinetic profile with encouraging preliminary antitumor activity in heavily pretreated patients with mesothelin-expressing solid tumors. The results allowed for the determination of recommended doses, schedules, and patient populations for anetumab ravtansine in phase II studies.

Emerging Treatments for Malignant Pleural Mesothelioma: Where Are We Heading?

Malignant pleural mesothelioma (MPM) is an uncommon but aggressive and treatment resistant neoplasm with low survival rates. In the last years we assisted to an exponential growth in the appreciation of mesothelioma pathobiology, leading several new treatments to be investigated both in the early stage of the disease and in the advanced setting. In particular, expectations are now high that immunotherapy will have a leading role in the next years. However, caution is required as results from phase II studies in MPM were often not replicated in larger, randomized, phase III trials. In this review, we describe the most promising emerging therapies for the treatment of MPM, discussing the biological rationale underlying their development as well as the issues surrounding clinical trial design and proper selection of patients for every treatment.