Allyson J. Ocean

Chemotherapy-induced peripheral neuropathy: pathogenesis and emerging therapies

Peripheral neuropathy is a major dose-limiting side effect of many chemotherapeutic agents. The type and degree of neuropathy depend on the chemotherapy drug, dose-intensity, and cumulative dose. Disabling peripheral neuropathy has a significant negative impact on quality of life. Accordingly, a reliable assessment of chemotherapy-induced peripheral neurotoxicity is necessary, especially if potential neuroprotective agents are to be investigated. Chemoprotectants are agents that have been developed to ameliorate the toxicity associated with cytotoxic drugs. They aim to provide site-specific protection for normal tissues, without compromising antitumor efficacy. Several chemoprotectant compounds have been studied in recent clinical trials. These trials must include sufficient dose-limiting events for study and assessment of both toxicity and antitumor effect. A future avenue of investigation includes the identification of patients at higher risk for the development of peripheral neuropathy based on their genotype. Identification of these higher-risk patients may enable us to devise prevention strategies prior to the onset of this potentially debilitating complication.

Peripheral Neuropathy with Microtubule-Targeting Agents: Occurrence and Management Approach

Microtubule-targeting agents (MTAs), which include vinca alkaloids, taxanes, and the recently introduced epothilone, ixabepilone, are widely used chemotherapeutic agents for treatment of patients with cancer. MTAs interfere with the normal structure and function of microtubules, leading to cell-cycle arrest and tumor cell death. Microtubule function is critical to normal neuronal function, thus MTA therapy is commonly associated with some form of neuropathy. There is poor agreement between tools for clinical assessment of MTA-associated peripheral neuropathy, and standardization of grading scales is needed to reduce variability. For a majority of patients, MTA-associated neuropathy is mild to moderate in intensity and reversible, but it can be severe and resolve incompletely. The incidence and severity of MTA-associated neuropathy is drug, dose, and schedule dependent. The first-generation vinca alkaloids (eg, vincristine) are associated with severe mixed sensory and motor neuropathy, whereas the newer vinca alkaloids (eg, vinorelbine, vinflunine) induce a milder sensory neuropathy. Taxane-associated sensory neuropathy occurs more often with standard (polyoxyethylated castor oil-based) and albumin-bound paclitaxel than with docetaxel. The incidence and presentation of peripheral neuropathy with ixabepilone, alone or in combination with capecitabine, are similar to that with taxanes. Management of neuropathy may involve reducing or delaying the MTA dose, or in severe persistent or disabling cases discontinuing treatment. Reversal of neuropathy after dosage intervention appears to be more rapid with ixabepilone than with other MTAs.

Fractionated radioimmunotherapy with 90Y-clivatuzumab tetraxetan and low-dose gemcitabine is active in advanced pancreatic cancer: A phase 1 trial

It has been demonstrated that the humanized clivatuzumab tetraxetan (hPAM4) antibody targets pancreatic ductal carcinoma selectively. After a trial of radioimmunotherapy that determined the maximum tolerated dose of single‐dose yttrium‐90‐labeled hPAM4 (90Y‐hPAM4) and produced objective responses in patients with advanced pancreatic ductal carcinoma, the authors studied fractionated radioimmunotherapy combined with low‐dose gemcitabine in this disease.

First-in-Human Trial of a Novel Anti-Trop-2 Antibody-SN-38 Conjugate, Sacituzumab Govitecan, for the Treatment of Diverse Metastatic Solid Tumors

Purpose: Sacituzumab govitecan (IMMU-132) is an antibody–drug conjugate (ADC) targeting Trop-2, a surface glycoprotein expressed on many epithelial tumors, for delivery of SN-38, the active metabolite of irinotecan. This phase I trial evaluated this ADC as a potential therapeutic for pretreated patients with a variety of metastatic solid cancers. Experimental Design: Sacituzumab govitecan was administered on days 1 and 8 of 21-day cycles, with cycles repeated until dose-limiting toxicity or progression. Dose escalation followed a standard 3 + 3 scheme with 4 planned dose levels and dose delay or reduction allowed. Results: Twenty-five patients (52–60 years old, 3 median prior chemotherapy regimens) were treated at dose levels of 8 (n = 7), 10 (n = 6), 12 (n = 9), and 18 (n = 3) mg/kg. Neutropenia was dose limiting, with 12 mg/kg the maximum tolerated dose for cycle 1, but too toxic with repeated cycles. Lower doses were acceptable for extended treatment with no treatment-related grade 4 toxicities and grade 3 toxicities limited to fatigue (n = 3), neutropenia (n = 2), diarrhea (n = 1), and leukopenia (n = 1). Using CT-based RECIST 1.1, two patients achieved partial responses (triple-negative breast cancer, colon cancer) and 16 others had stable disease as best response. Twelve patients maintained disease control with continued treatment for 16 to 36 weeks; 6 survived 15 to 20+ months. No preselection of patients based on tumor Trop-2 expression was done. Conclusions: Sacituzumab govitecan had acceptable toxicity and encouraging therapeutic activity in patients with difficult-to-treat cancers. The 8 and 10 mg/kg doses were selected for phase II studies. Clin Cancer Res; 21(17); 3870–8. ©2015 AACR.

Randomized Multicenter Phase II Study of Modified Docetaxel, Cisplatin, and Fluorouracil (DCF) Versus DCF Plus Growth Factor Support in Patients With Metastatic Gastric Adenocarcinoma: A Study of the US Gastric Cancer Consortium

PURPOSE Docetaxel, cisplatin, and fluorouracil (DCF) is a standard first-line three-drug chemotherapy regimen for advanced gastric or gastroesophageal junction (GEJ) adenocarcinoma and is associated with significant toxicity. We examined the safety and efficacy of a modified DCF (mDCF) regimen in a randomized multicenter phase II study. PATIENTS AND METHODS Previously untreated patients with metastatic gastric or GEJ adenocarcinoma were randomly assigned to receive either mDCF (fluorouracil 2,000 mg/m2 intravenously [IV] over 48 hours, docetaxel 40 mg/m2 IV on day 1, cisplatin 40 mg/m2 IV on day 3, every 2 weeks) or parent DCF (docetaxel 75 mg/m2, cisplatin 75 mg/m2, and fluorouracil 750 mg/m2 IV over 5 days with granulocyte colony-stimulating factor, every 3 weeks). The study had 90% power to differentiate between 6-month progression-free survival of 26% and 43%, with type I and II error rates of 10% each. An early stopping rule for toxicity was included, defined as grade 3 to 4 adverse event rate > 70% in the first 3 months. RESULTS From November 2006 to June 2010, 85 evaluable patients were enrolled (male, n = 61; female, n = 24; median age, 58 years; Karnofsky performance status, 90%; GEJ, n = 28; gastric, 57). mDCF (n = 54) toxicity rates included 54% grade 3 to 4 toxicity (22% hospitalized) within the first 3 months and 76% grade 3 to 4 toxicity over the course of treatment. The DCF arm (n = 31) closed early because of toxicity, with rates of 71% grade 3 to 4 toxicity (52% hospitalized) within 3 months and 90% grade 3 to 4 toxicity over the course of treatment. Six-month PFS was 63% (95% CI, 48% to 75%) for mDCF and 53% (95% CI, 34% to 69%) for DCF. Median overall survival was improved for mDCF (18.8 v 12.6 months; P = .007). CONCLUSION mDCF is less toxic than parent DCF, even when supported with growth factors, and is associated with improved efficacy. mDCF should be considered a standard first-line option for patients with metastatic gastric or GEJ adenocarcinoma.

Efficacy and Safety of Anti-Trop-2 Antibody Drug Conjugate Sacituzumab Govitecan (IMMU-132) in Heavily Pretreated Patients With Metastatic Triple-Negative Breast Cancer

Purpose Trop-2, expressed in most triple-negative breast cancers (TNBCs), may be a potential target for antibody-drug conjugates. Sacituzumab govitecan, an antibody-drug conjugate, targets Trop-2 for the selective delivery of SN-38, the active metabolite of irinotecan. Patients and Methods We evaluated sacituzumab govitecan in a single-arm, multicenter trial in patients with relapsed/refractory metastatic TNBC who received a 10 mg/kg starting dose on days 1 and 8 of 21-day repeated cycles. The primary end points were safety and objective response rate; secondary end points were progression-free survival and overall survival. Results In 69 patients who received a median of five prior therapies (range, one to 12) since diagnosis, the confirmed objective response rate was 30% (partial response, n = 19; complete response, n = 2), the median response duration was 8.9 (95% CI, 6.1 to 11.3) months, and the clinical benefit rate (complete response + partial response + stable disease ≥ 6 months) was 46%. These responses occurred early, with a median onset of 1.9 months. Median progression-free survival was 6.0 (95% CI, 5.0 to 7.3) months, and median overall survival was 16.6 (95% CI, 11.1 to 20.6) months. Grade ≥ 3 adverse events included neutropenia (39%), leukopenia (16%), anemia (14%), and diarrhea (13%); the incidence of febrile neutropenia was 7%. The majority of archival tumor specimens (88%) were moderately to strongly positive for Trop-2 by immunohistochemistry. No neutralizing antibodies to the ADC or antibody were detected, despite repeated cycles developed. Conclusion Sacituzumab govitecan was well tolerated and induced early and durable responses in heavily pretreated patients with metastatic TNBC. As a therapeutic target and predictive biomarker, Trop-2 warrants further research.

Phase II Study of Paclitaxel plus the Protein Kinase C Inhibitor Bryostatin-1 in Advanced Pancreatic Carcinoma

Purpose:To determine the efficacy and toxicity of the protein kinase C inhibitor bryostatin-1 plus paclitaxel in patients with advanced pancreatic carcinoma. Methods:Each treatment cycle consisted of paclitaxel 90 mg/m2 by intravenous infusion over 1 hour on days 1, 8, and 16, plus bryostatin 25 mcg/m2 as a 1-hour intravenous infusion on days 2, 9, and 15, given every 28 days. Patients were evaluated for response after every 2 treatment cycles, and continued therapy until disease progression or prohibitive toxicity. The primary objective was to determine whether the combination produced a response rate of at least 30%. Results:Nineteen patients with locally advanced or metastatic pancreatic adenocarcinoma received a total of 52 cycles of therapy (range: 1–10). Patients received the combination as first-line therapy for advanced disease (N = 5) or after prior chemotherapy used alone or in combination with local therapy. No patients had a confirmed objective response. The median time to treatment failure was 1.9 months (95% confidence intervals: 1.2, 2.6 months). Reasons for discontinuing therapy included progressive disease or death in 14 patients (74%) or because of adverse events or patient choice in 5 patients (26%). The most common grade 3 to 4 toxicities included leukopenia in 26%, anemia in 11%, myalgias in 11%, gastrointestinal bleeding in 11%, infection in 10%, and thrombosis in 10%. Conclusion:The combination of weekly paclitaxel and bryostatin-1 is not an effective therapy for patients with advanced pancreatic carcinoma.

Sacituzumab Govitecan, a Novel Antibody–Drug Conjugate, in Patients With Metastatic Platinum-Resistant Urothelial Carcinoma

Patients with metastatic, platinum-resistant urothelial carcinoma (PRUC) have no Food and Drug Administration-approved therapies. The response rates to second-line chemotherapy have generally been < 20%, with a median overall survival of < 1 year. We report our experience with 6 heavily pretreated patients with advanced PRUC (ClinicalTrials.gov identifier NCT01631552) with the novel antibody-drug conjugate, sacituzumab govitecan (IMMU-132). This antibody-drug conjugate comprises the active metabolite of irinotecan, SN-38, conjugated to an anti-Trop-2 antibody. Trop-2 is widely expressed in ≤ 83% of urothelial carcinomas. Of the 6 patients, 3 had a clinically significant response (progression-free survival, 6.7 to 8.2 months; overall survival, 7.5+ to 11.4+ months). Sacituzumab govitecan was well tolerated. Because of these results, a phase II trial has been initiated. The present report highlights the promise of antibody-drug conjugates, such as sacituzumab govitecan, as a novel therapeutic strategy for the treatment of PRUC.

Organoid profiling identifies common responders to chemotherapy in pancreatic cancer

Pancreatic cancer is the most lethal common solid malignancy. Systemic therapies are often ineffective, and predictive biomarkers to guide treatment are urgently needed. We generated a pancreatic cancer patient-derived organoid (PDO) library that recapitulates the mutational spectrum and transcriptional subtypes of primary pancreatic cancer. New driver oncogenes were nominated and transcriptomic analyses revealed unique clusters. PDOs exhibited heterogeneous responses to standard-of-care chemotherapeutics and investigational agents. In a case study manner, we found that PDO therapeutic profiles paralleled patient outcomes and that PDOs enabled longitudinal assessment of chemosensitivity and evaluation of synchronous metastases. We derived organoid-based gene expression signatures of chemosensitivity that predicted improved responses for many patients to chemotherapy in both the adjuvant and advanced disease settings. Finally, we nominated alternative treatment strategies for chemorefractory PDOs using targeted agent therapeutic profiling. We propose that combined molecular and therapeutic profiling of PDOs may predict clinical response and enable prospective therapeutic selection.Significance: New approaches to prioritize treatment strategies are urgently needed to improve survival and quality of life for patients with pancreatic cancer. Combined genomic, transcriptomic, and therapeutic profiling of PDOs can identify molecular and functional subtypes of pancreatic cancer, predict therapeutic responses, and facilitate precision medicine for patients with pancreatic cancer. Cancer Discov; 8(9); 1112-29. ©2018 AACR.See related commentary by Collisson, p. 1062This article is highlighted in the In This Issue feature, p. 1047.

Therapy of Advanced Non–Small-Cell Lung Cancer With an SN-38-Anti-Trop-2 Drug Conjugate, Sacituzumab Govitecan

Purpose Trop-2, expressed in most solid cancers, may be a target for antibody-drug conjugates (ADCs) in non-small-cell lung cancer (NSCLC). We studied sacituzumab govitecan (IMMU-132), a Trop-2 ADC, for the targeting of SN-38. Patients and Methods We evaluated IMMU-132 in a single-arm multicenter trial in patients with pretreated metastatic NSCLC who received either 8 or 10 mg/kg on days 1 and 8 of 21-day cycles. The primary end points were safety and objective response rate (ORR). Progression-free survival and overall survival were secondary end points. Results Fifty-four patients were treated. In the response-assessable study population (n = 47), which had a median of three prior therapies (range, two to seven), the ORR was 19%; median response duration, 6.0 months (95% CI, 4.8 to 8.3 months); and clinical benefit rate (complete response + partial response + stable disease ≥ 4 months), 43%. ORR in the intention-to-treat (ITT) population was 17% (nine of 54). Responses occurred with a median onset of 3.8 months, including patients who had relapsed or progressed after immune checkpoint inhibitor therapy. Median ITT progression-free survival was 5.2 months (95% CI, 3.2 to 7.1 months) and median ITT overall survival, 9.5 months (95% CI, 5.9 to 16.7 months). Grade 3 or higher adverse events included neutropenia (28%), diarrhea (7%), nausea (7%), fatigue (6%), and febrile neutropenia (4%). One patient developed a transient immune response, despite patients receiving a median of 10 doses. More than 90% of 26 assessable archival tumor specimens were highly positive (2+, 3+) for Trop-2 by immunohistochemistry, which suggests that Trop-2 is not a predictive biomarker for response. Conclusion IMMU-132 was well-tolerated and induced durable responses in heavily pretreated patients with metastatic NSCLC. This ADC should be studied further in this disease and in other patients with Trop-2-expressing tumors.