Real-world application of tumor mutational burden-high (TMB-high) and microsatellite instability (MSI) confirms their utility as immunotherapy biomarkers

Introduction

Microsatellite instability (MSI) testing and tumor mutational burden (TMB) are genomic biomarkers used to identify patients who are likely to benefit from immune checkpoint inhibitors. Pembrolizumab was recently approved by the Food and Drug Administration for use in TMB-high (TMB-H) tumors, regardless of histology, based on KEYNOTE-158. The primary objective of this retrospective study was real-world applicability and use of immunotherapy in TMB/MSI-high patients to lend credence to and refine this biomarker.

Methods

Charts of patients with advanced solid tumors who had MSI/TMB status determined by next generation sequencing (NGS) (FoundationOne CDx) were reviewed. Demographics, diagnosis, treatment history, and overall response rate (ORR) were abstracted. Progression-free survival (PFS) was determined from Kaplan–Meier curves. PFS1 (chemotherapy PFS) and PFS2 (immunotherapy PFS) were determined for patients who received immunotherapy after progressing on chemotherapy. The median PFS2/PFS1 ratio was recorded.

Results

MSI-high or TMB-H [≥20 mutations per megabase (mut/MB)] was detected in 157 adults with a total of 27 distinct tumor histologies. Median turnaround time for NGS was 73 days. ORR for most recent chemotherapy was 34.4%. ORR for immunotherapy was 55.9%. Median PFS for patients who received chemotherapy versus immunotherapy was 6.75 months (95% confidence interval, 3.9-10.9 months) and 24.2 months (95% confidence interval, 9.6 months to not reached), respectively (P = 0.042). Median PFS2/PFS1 ratio was 4.7 in favor of immunotherapy.

Conclusion

This real-world study reinforces the use of TMB as a predictive biomarker. Barriers exist to the timely implementation of NGS-based biomarkers and more data are needed to raise awareness about the clinical utility of TMB. Clinicians should consider treating TMB-H patients with immunotherapy regardless of their histology.

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This retrospective study examined the real-world use of immune checkpoint inhibitors (ICIs) in TMB/MSI-high patients with a diverse set of cancer types.

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TMB is an emerging tumor-agnostic biomarker for response to treatment with ICIs that may expand personalized cancer care.

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ICIs remain underutilized as a first-line therapy for TMB/MSI-H patients without specific histologic approval for ICIs.

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The PFS2 to PFS1 ratio was 4.7, favoring immunotherapy over chemotherapy even as a second-line therapy.

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Our study reinforces the real-world evidence that TMB is a valid surrogate marker for MSI and can predict response to ICIs.

Abstract P4-22-21: NCI9782: A phase 1 study of talazoparib in combination with carboplatin and paclitaxel in patients with advanced solid tumors

Background: Poly(ADP-ribose) polymerase (PARP) enzymes are involved in DNA repair and activated by DNA strand breaks. DNA damage from carboplatin is associated with activation of PARP. Preclinical data indicate that PARP inhibition potentiates the anti-tumor effect of platinum chemotherapy. Talazoparib (T) is an oral, selective PARP inhibitor with a single agent maximum tolerated dose (MTD) of 1mg orally qd. Primary dose-limiting toxicity (DLT) was thrombocytopenia. This phase I study combines T with the commonly used chemotherapy regimen of carboplatin (C) and paclitaxel (P).

Methods: Two dosing schedules are being investigated. In both schedules, C is administered on day 1 and P on days 1, 8, and 15 of a 21-day cycle. T (100-1000mcg) is dosed once daily for days 1-7 (schedule A) or days 1-3 (schedule B) starting on day 1. A 3+3 design is used for dose escalation. Key eligibility criteria include age 318 with a measurable or evaluable solid incurable malignancy. Patients (pts) must have tumor type that is expected to respond to C + P or have BRCA germline or somatic mutation. Stable, treated brain metastases are allowed. No prior C for metastatic disease is allowed. Pts must have platelets>150 and no need for anticoagulation. After 4-6 cycles of combination therapy, pts may continue the combination, change to C and intermittent T without P or change to T alone with continuous daily dosing. Each schedule will have a 6 subject dose expansion at the MTD. The starting dose level for schedule B will be the MTD from schedule A.

Results: Schedule A cohort results are reported: 11 pts (median age 59 [range 39-68]; 8 female; 3 male) have been enrolled. Pts had breast (6), ovarian (2), pancreatic (1), and SCC of oropharynx (1) and concurrent ovarian and pancreatic (1). Five pts are BRCA2+ and 3 pts are BRCA1+. Dose level 3 on schedule A (T 350mcg with C AUC 6 and P 80mg/m2) exceeded the MTD with 2 of 3 pts experiencing hematologic dose limiting toxicities (DLTs) including 1 pt with grade (gr) 3 neutropenic fever and gr 4 thrombocytopenia and another pt with grade 3/4 neutropenia lasting > 7 days. Most common AEs include neutropenia (grade 3-4: 7), anemia (grade 3-4: 3), and thrombocytopenia (grade 3-4: 4). Results from expansion of dose level 2 (T 250mcg with C AUC 6 and T 80mg/m2) will be presented. The 11 pts were on study a median of 9 weeks (range 9-36+). Four pts have discontinued study therapy: 1 due to need for anticoagulation for PE, 1 for prolonged cytopenias, and 2 for disease progression. Of the 8 pts with measurable disease evaluated for response to date, 4 had SD, 1 had a cPR, 1 had radiographic CR, and 2 with PD. A pt with BRCA 1+ triple negative breast cancer has maintained a prolonged PR (36+ weeks) even after dose reductions to T 100mcg with C AUC 3. One pt with ovarian cancer (BRCA WT) has radiographic CR (CA 125 remains mildly elevated) after 15+ weeks of therapy.

Conclusion: PARP inhibition with talazoparib days 1-7 in combination with carboplatin and paclitaxel leads to DLT of myelosuppression. However, clinical responses are seen even with lower dose combinations.

Citation Format: Turk A, Chan N, Leal T, O'Regan R, Tevaarwerk A, Rice L, Campbell T, Barroilhet L, Mehnert J, Eickhoff J, Kolesar J, Liu G, Wisinski K. NCI9782: A phase 1 study of talazoparib in combination with carboplatin and paclitaxel in patients with advanced solid tumors [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P4-22-21.

Phase I study of gemcitabine, docetaxel, and imatinib in refractory and relapsed solid tumors

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Background: The combination of the tyrosine kinase inhibitor imatinib with cytotoxic chemotherapy targets multiple pathways of tumor progression. In a previous phase I study, the combination of gemcitabine and imatinib was tolerable and had broad activity. The maximally tolerated dose (MTD) was gemcitabine 1500 mg/m2/150 minute and imatinib 400 mg days 1–5, 8–12, and 15–19. Given the activity seen when combining gemcitabine and docetaxel in some solid tumors, this phase I trial studied the addition of docetaxel to gemcitabine/imatinib. Methods: Twenty patients with relapsed/refractory solid tumors were enrolled in this IRB-approved study at the Cancer Institute of New Jersey and University of Michigan. The mean age was 64, mean ECOG PS 1. Five patients had lung cancer; 5, sarcoma; 3 ampullary-biliary tumors; 2 mesothelioma and bladder, 3, other. Imatinib was administered at 400 mg daily on days 1–5, 8–12 and 15–19. Gemcitabine was started at 600 mg/m2 at the fixed dose infusion of 10 mg/min on days 3 and 10 and docetaxel at 30 mg/m2 on day 10. Results: Because of unexpectedly severe hematological toxicities seen with escalating either gemcitabine or docetaxel, the protocol was amended to eliminate days 15–19 of imatinib. The MTD is gemcitabine 600 mg/m2, on days 3 and 10, docetaxel 30 mg/m2 on day 10, and imatinib 400 mg PO given on days 1–5 and 8–12. The dose limiting toxicities were neutropenic fever, pleural and pericardial effusion after cycle 1 of chemotherapy. The best response achieved was stable disease at 6 cycles in one patient each with mesothelioma and non small cell lung cancer (NSCLC) at the MTD. Two other patients with NSCLC had stable disease at 4 cycles. Discussion: An unexpectedly low MTD for this triplet was identified, an outcome different from prior experience with the doublets gemcitabine/imatinib or gemcitabine/docetaxel where much higher dosages are tolerated. Our results suggest possible drug-drug interactions that amplify toxicities with little initial evidence of improved tumor control. Given the unexpectedly high toxicity of the combination of gemcitabine, docetaxel and imatinib at low dosages, further development of this regimen is not indicated.

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Rationally designed treatment for solid tumors with MAPK pathway activation

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Background: Preclinical studies shed light to the mechanism conferring paclitaxel resistance in solid tumors with active Ras/Raf/Mitogen-Activated Protein Kinase (MAPK) pathway, and determined a molecular mechanism by which addition of the proteasome inhibitor bortezomib abrogated this resistance, enabling tumor regression in animals in vivo. Methods: A Phase I study was contacted to determine the MTD of paclitaxel and bortezomib combinatorial treatment. Sixteen patients with refractory solid tumors were treated with weekly paclitaxel and bortezomib. Six patients had NSCLC; 4, colon cancer; 2, pancreatic; 2, melanoma; 1, breast; 1, ovarian. Patients with baseline neuropathy greater than or equal to Grade 1 were excluded. The starting dose was 40 mg/m2 for paclitaxel and 0.7 mg/m2 for bortezomib. A modified continual reassessment method (MCRM) was used for dose escalation with 3-patient cohorts treated at each dose level. The Target Toxicity Level (probability of DLT at the MTD) was set at 25%. Maximum dose escalation was no more than 75% of the previous SED level, if no Grade 3 hematologic toxicity or DLT were observed. Otherwise, the maximum dose escalation was no more than 50% of the previous SED level. The process continued until SED changes were no more than 10% for two consecutive cohorts. Results: The MTD for the combinatorial treatment was reached at 60 mg/m2 paclitaxel and 1.0 mg/m2 bortezomib. Of 15 evaluable patients, 1 patient with paclitaxel-resistant NSCLC had PR and 5 patients (2, NSCLC; 1, pancreatic; 1, colon; 1, ovarian) had stable disease. Median TTP was 2.3 months (0.8 to 6 months). Three NSCLC patients achieved TTP longer than 5 months. The combination of paclitaxel and bortezomib was relatively well tolerated. Paclitaxel PK parameters are being determined, and paraffin-embedded tumor specimens are being evaluated for MAPK pathway activation by IHC for phospho-ERK. Results will be correlated with clinical response. Conclusions: The MTD for the proposed combinatorial treatment is 60 mg/m2 for paclitaxel and 1.0 mg/m2 for bortezomib, and is relatively well tolerated. Combination of paclitaxel with bortezomib is effective in taxane-resistant NSCLC, and worthy of further investigation.

No significant financial relationships to disclose.

Phase I trial of patupilone (P) and RAD001 in patients (pts) with advanced solid tumors

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Background: P is an epothilone with activity in solid tumors including docetaxel (D) resistant prostate cancer. R is an oral mTOR inhibitor that demonstrates synergy with P in pre-clinical models, possibly by decreasing resistance to apoptosis. This on-going phase I study is assessing the tolerability of P in combination with R in pts with advanced solid tumors. Methods: Eligible patients with ECOG PS 0–2, adequate organ function and no more than 3 prior chemotherapy treatment received P every 21 days and weekly R using a standard 3+3 dose escalation schema in a 21 day(d) cycle starting at 50% of the phase II dose of P and 60% of the standard weekly dosing of R. Dosing levels are (1) P 5mg/m2 D1, R 30mg D1; (2) P 7.5mg/m2 D1, R 30mg D1 (3) P 7.5mg/m2 D1 R 30mg D1, D8 (3A) P 7.5mg/m2 D1 R 30mg D1, D8, D15 (3B) P 8mg/m2 D1 R 50mg D1, D8 (4) P 10 mg/m2 D1, D8 R 30mg D1, D8 (5) P 10 mg/m2 D1, D8 R 50mg D1, D8. Pharmacokinetic (PK) levels of R were obtained D1, D2 and PBMC were obtained to assess phospho-S6 and to assess markers of apoptosis and autophagy. Results: A total of 24 pts have been enrolled and 23 pts are evaluable for toxicity (tumor types: colon-7, prostate-6, lung-3, ampulla-3, leiomyosarcoma-2, cervical cancer-1). DLTs of grade(g) 3 diarrhea, g3 colitis and g3 fatigue were observed in dose levels 5, 4 and 1 pt in cohort 3A with a colostomy. Cohorts 1–3 were well tolerated with the common AEs of g1 diarrhea, g2 neuropathy after cycle 7, g1/g2 anemia, g1 triglycerides. In pts with prostate cancer (all previously pretreated with D) PSA declines of >50% occurred in 3/5 pts treated with >2 cycles; 1/7 pts with colon cancer had a PR and 3/7 pts with colon cancer had stable disease (SD) > 8 cycles; 1/3 pts with ampullary ca had a PR and a pt with cervical ca had SD x10 cycles. Conclusions: P 7.5mg/m2 and R 30mg D1, D8 is safe and well tolerated. Encouraging evidence of clinical activity is observed in prostate, colon and other tumor types. Enrollment to cohort 3A is ongoing.

[Table: see text]

[The use of Ornipressin in dental local anesthesia]

Blood-pressure and pulse-rate measurements, sensibility tests and tissue clearance measurements were performed in juvenile patients aged from 12 to 18 years to evaluate the clinical effects and side-effects of the new vasoconstrictor POR 8 (ornipressin) in ambulatory dental treatments. There were no significant differences in efficiency compared to adrenaline. Indications for the use of POR 8 are mentioned.