A phase II study of higher dose weekly topotecan in relapsed small-cell lung cancer

Advances in Treatment of Recurrent Small Cell Lung Cancer (SCLC): Insights for Optimizing Patient Outcomes from an Expert Roundtable Discussion

Second-line treatment options for patients with relapsed, extensive-stage small cell lung cancer (ES-SCLC) are limited, and even with currently available treatments, prognosis remains poor. Until recently, topotecan (a topoisomerase I inhibitor) was the only drug approved by the United States (US) Food and Drug Administration (FDA) for the management of ES-SCLC following progression after first-line treatment with etoposide plus a platinum derivative (EP; carboplatin preferred). With the most recent approval of EP plus a programmed death ligand 1 (PD-L1) inhibitor, there are now more therapeutic options for managing ES-SCLC. A number of novel agents have emerging data for activity in relapsed ES-SCLC, and single-agent lurbinectedin (an alkylating drug and selective inhibitor of oncogenic transcription and DNA repair machinery in tumor cells) has conditional FDA approval for use in this patient population. Trilaciclib, a short-acting cyclin-dependent kinase 4/6 (CDK 4/6) inhibitor, has also been recently approved as a supportive intervention for use prior to an EP or a topotecan-containing regimen to diminish the incidence of chemotherapy-induced myelosuppression. The current review is based on a recent expert roundtable discussion and summarizes current therapeutic agents and emerging data on newer agents and biomarkers. It also provides evidence-based clinical considerations and a treatment decision tool for oncologists treating patients with relapsed ES-SCLC. This paper discusses the importance of various factors to consider when selecting a second-line treatment option, including prior first-line treatment, available second-line treatment options, tumor platinum sensitivity, and patient characteristics (such as performance status, comorbidities, and patient-expressed and perceived values).

Inhibition of the Replication Stress Response Is a Synthetic Vulnerability in SCLC That Acts Synergistically in Combination with Cisplatin

Small cell lung cancer (SCLC) is generally regarded as very difficult to treat, mostly due to the development of metastases early in the disease and a quick relapse with resistant disease. SCLC patients initially show a good response to treatment with the DNA damaging agents cisplatin and etoposide. This is, however, quickly followed by the development of resistant disease, which urges the development of novel therapies for this type of cancer. In this study, we set out to compile a comprehensive overview of the vulnerabilities of SCLC. A functional genome-wide screen where all individual genes were knocked out was performed to identify novel vulnerabilities of SCLC. By analysis of the knockouts that were lethal to these cancer cells, we identified several processes to be synthetic vulnerabilities in SCLC. We were able to validate the vulnerability to inhibition of the replication stress response machinery by use of Chk1 and ATR inhibitors. Strikingly, SCLC cells were more sensitive to these inhibitors than nontransformed cells. In addition, these inhibitors work synergistically with either etoposide and cisplatin, where the interaction is largest with the latter. ATR inhibition by VE-822 treatment in combination with cisplatin also outperforms the combination of cisplatin with etoposide in vivo Altogether, our study uncovered a critical dependence of SCLC on the replication stress response and urges the validation of ATR inhibitors in combination with cisplatin in a clinical setting.

Current Treatments for Surgically Resectable, Limited-Stage, and Extensive-Stage Small Cell Lung Cancer

The prevalence of small cell lung cancer (SCLC) has declined in the U.S. as the prevalence of tobacco use has declined. However, a significant number of people in the U.S. are current or former smokers and are at risk of developing SCLC. Routine histological or cytological evaluation can reliably make the diagnosis of SCLC, and immunohistochemistry stains (thyroid transcription factor-1, chromogranin, synaptophysin, and CD56) can be used if there is uncertainty about the diagnosis. Rarely do patients present with SCLC amendable to surgical resection, and evaluation requires a meticulous workup for extra-thoracic metastases and invasive staging of the mediastinum. Resected patients require adjuvant chemotherapy and/or thoracic radiation therapy (TRT), and prophylactic cranial radiation (PCI) should be considered depending on the stage. For limited-stage disease, concurrent platinum-etoposide and TRT followed by PCI is the standard. Thoracic radiation therapy should be started early in treatment, and can be given twice daily to 45 Gy or once daily to 60-70 Gy. For extensive-stage disease, platinum-etoposide remains the standard first-line therapy, and the standard second-line therapy is topotecan. Preliminary studies have demonstrated the activity of immunotherapy, and the response rate is approximately 10-30% with some durable responses observed. Rovalpituzumab tesirine, an antibody drug conjugate, has shown promising activity in patients with high delta-like protein 3 tumor expression (approximately 70% of patients with SCLC). The emergence of these and other promising agents has rekindled interest in drug development in SCLC. Several ongoing trials are investigating novel agents in the first-line, maintenance, and second-line settings.

IMPLICATIONS FOR PRACTICE

This review will provide an update on the standard therapies for surgically resected limited-stage small cell lung cancer and extensive-stage small cell lung cancer that have been investigated in recent clinical trials.

Chemotherapeutic Dose Scheduling Based on Tumor Growth Rates Provides a Case for Low-Dose Metronomic High-Entropy Therapies

We extended the classical tumor regression models such as Skipper's laws and the Norton-Simon hypothesis from instantaneous regression rates to the cumulative effect over repeated cycles of chemotherapy. To achieve this end, we used a stochastic Moran process model of tumor cell kinetics coupled with a prisoner's dilemma game-theoretic cell-cell interaction model to design chemotherapeutic strategies tailored to different tumor growth characteristics. Using the Shannon entropy as a novel tool to quantify the success of dosing strategies, we contrasted MTD strategies as compared with low-dose, high-density metronomic strategies (LDM) for tumors with different growth rates. Our results show that LDM strategies outperformed MTD strategies in total tumor cell reduction. This advantage was magnified for fast-growing tumors that thrive on long periods of unhindered growth without chemotherapy drugs present and was not evident after a single cycle of chemotherapy but grew after each subsequent cycle of repeated chemotherapy. The evolutionary growth/regression model introduced in this article agrees well with murine models. Overall, this model supports the concept of designing different chemotherapeutic schedules for tumors with different growth rates and develops quantitative tools to optimize these schedules for maintaining low-volume tumors. Cancer Res; 77(23); 6717-28. ©2017 AACR.

Topotecan for Relapsed Small-cell Lung Cancer: Systematic Review and Meta-Analysis of 1347 Patients

Topotecan is the most reliable chemotherapy regimen for relapsed small-cell lung carcinoma (SCLC). The efficacy and adverse effects of topotecan as reported by previous studies varied greatly. The inclusion criterion was a prospective study that was able to provide data for 6-month over-all survival (OS) rate, 1-year OS rate, objective responses, and/or adverse effects of single agent topotecan as a second line chemotherapy for SCLC, written in English language as a full article. Any topotecan regimen were allowed. Binary data were meta-analyzed with the random-model generic inverse variance method. We included 14 articles consisted of 1347 patients. Pooled values were estimated as follows. Six-month OS rate: 37% (95% CI: 28-46%). One-year OS rate: 9% (95% CI: 5-13%). Response rate: 5% (95% CI: 1-8%). Six-month OS rate: 57% (95% CI: 50-64%). One-year OS rate: 27% (95% CI: 22-32%). Response rate: 17% (95% CI: 11-23%). Grade III/IV neutropenia 69% (95% CI: 58-80%). Grade III/IV thrombopenia 41% (95% CI: 34-48%). Grade III/IV anemia 24% (95% CI: 17-30%). Non-hematorogical events were rare. Chemotherapy-related death 2% (95% CI: 1-3%). In conclusion, Topotecan provided a possibly promising outcome for sensitive-relapse SCLC and poor outcome for refractory relapse SCLC. Adverse events were mainly hematological.

Treatment of small cell lung cancer

Treatment of small cell lung cancer (SCLC) remains a significant challenge for the oncologists. Attempts to improve the results of first-line treatment have all failed so far and no real progress has been made in last years, emphasizing the need for novel strategies of treatment and the development of validated biomarkers. Patients with limited disease and good performance status should be considered for concomitant chemoradiotherapy, followed by prophylactic cranial irradiation. Patients with extensive disease should be treated with a platinum-based chemotherapy (cisplatin or carboplatin); chest radiotherapy can be considered in patients achieving extra-thoracic complete response and prophylactic cranial irradiation is recommended for patients responsive to initial chemotherapy. A large number of molecular-targeted drugs and immunomodulators are currently in clinical development: however, only a better understanding of molecular biology of SCLC and the identification of molecular markers predictive of response to targeted agents will lead to advances in the treatment of SCLC.

A phase I clinical trial of weekly oral topotecan for relapsed small cell lung cancer

PURPOSE

To determine the dose-limiting toxicities (DLTs) and the maximum tolerated dose (MTD) of oral topotecan administered weekly in patients with relapsed small cell lung cancer (SCLC).

PATIENTS AND METHODS

Patients were treated with oral topotecan on days 1, 8, and 15, every 28 days. The dose was escalated by 0.5 mg/m² increments from the starting dose of 3 mg/m² until the MTD was reached. DLTs were defined as grade 4 neutropenia, febrile neutropenia, grade 4 thrombocytopenia, non-hematologic toxicity ≥grade 3, any toxicity precluding the treatment on days 8 or 15 of the first cycle, or delay of the second cycle for more than 7 days.

RESULTS

Eighteen patients were enrolled. Thirteen patients received oral topotecan as second-line and five as third- or further-line treatment. The DLT level was reached at 4.5 mg/m², and the MTD was determined to be 4 mg/m². DLTs consisted of grade 2/3 neutropenia and grade 2 thrombocytopenia precluding treatment on day 15 of the first cycle or on day 1 of the second cycle. The most frequent toxicities were grade 2-3 neutropenia (27.8 % of patients), grade 2-3 anemia (33.3 %), grade 2 thrombocytopenia (16.7 %), and grade 2-3 fatigue (44.4 %). The response rate was 11.1 %, the median progression-free survival 2.3 months, and the median overall survival 5.1 months.

CONCLUSION

The recommended phase II dose of weekly oral topotecan in pretreated patients with SCLC is 4 mg/m² on days 1, 8, and 15 every 28 days.

Efficacy and safety of oral topotecan and bevacizumab combination as second-line treatment for relapsed small-cell lung cancer: an open-label multicenter single-arm phase II study

BACKGROUND

Topotecan is currently the only US Federal Drug Administration (FDA)-approved drug for second-line treatment of relapsed small-cell lung cancer (SCLC). We investigated the efficacy and safety of a novel topotecan-bevacizumab combination in treating relapsed SCLC.

PATIENTS AND METHODS

Each 21-day treatment cycle consisted of bevacizumab (15 mg/kg) administration on day 1 and oral topotecan (2.3 mg/m(2)/d) administration on days 1 to 5. Treatment was continued for 8 cycles or until disease progression/toxicity. The primary objective was evaluation of 3-month progression-free survival (PFS). Overall response rate (ORR), duration of response, time to response (TTR), and overall survival (OS) were secondary objectives.

RESULTS

The study enrolled 50 patients between July 2008 and May 2010. The 3-month PFS was 65% (95% confidence interval [CI], 49.3%-76.9%), which was promising compared with the historical control of 50% (P = .017) but did not meet the predefined criteria for clinically meaningful improvement. Median PFS was 6.24 months for the sensitive subgroup (progression time from end of previous chemotherapy > 90 days; n = 27) and 2.91 months for the resistant subgroup (progression time ≤ 90 days; n = 23). No patient achieved complete response (CR), and the ORR was 16%. Twenty (40%) patients had stable disease (SD) and 13 (26%) had progressive disease (PD). Median OS, TTR, and duration of response were 7.4, 1.3, and 4.7 months, respectively. The worst reported adverse events (AEs) were grade 1/2 in 11 (22%) patients and grade 3/4/5 in 39 (78%) patients.

CONCLUSION

Improvement in the 3-month PFS after treatment with topotecan-bevacizumab was promising compared with the historical control and justifies additional studies with this regimen.