[Metronomic chemotherapy with oral cyclophosphamide : An individual option for the metastatic castration-resistant prostate cancer patient?]

Oral Cyclophosphamide for Patients With Metastatic Castration-Resistant Prostate Cancer in a Scenario of Limited Health Care Resources

PURPOSE

Prior noncontemporary studies showed that oral cyclophosphamide is an active treatment of metastatic castration-resistant prostate cancer (mCRPC). However, cyclophosphamide is currently underutilized in routine clinical practice given the lack of survival benefit and the emergence of more effective treatments.

METHODS

We retrospectively reviewed our institutional database to identify patients with mCRPC treated with cyclophosphamide. Prostate-specific antigen decrease ≥50% from baseline (PSA50) response was determined as the proportion of patients achieving a prostate-specific antigen (PSA) decline ≥50% from baseline. Radiographic responses and progression were evaluated by Prostate Cancer Working Group 3. Survival estimates used the Kaplan-Meier method, and correlations were made with Chi-square test for categorical variables.

RESULTS

From January 2011 to January 2023, 341 patients with mCRPC received oral cyclophosphamide at a tertiary cancer center in São Paulo, Brazil. The most common regimen (95%) was 100 mg once daily 21 days on, 7 days off. At prostate cancer diagnosis, the median age was 64.4 years (IQR, 59.4-70.8), 61.9% had metastatic de novo disease, and 55.5% had Gleason ≥8. The median number of previous treatment lines was three (IQR, 2-4). Any PSA decline was observed in 33.4%, and 13.2% had a PSA50 response. Median response duration was 2.1 months (IQR, 1.4-3.8). Ten patients (3%) were treated for ≥1 year. PSA50 response was associated with no prior docetaxel use and Eastern Cooperative Oncology Group performance status 0 or 1.

CONCLUSION

Oral cyclophosphamide is a feasible treatment option for patients with mCRPC, particularly in a scenario of limited health care resources.

Optimizing cancer therapy: a review of the multifaceted effects of metronomic chemotherapy

Metronomic chemotherapy (MCT), characterized by the continuous administration of chemotherapeutics at a lower dose without prolonged drug-free periods, has garnered significant attention over the last 2 decades. Extensive evidence from both pre-clinical and clinical settings indicates that MCT induces distinct biological effects than the standard Maximum Tolerated Dose (MTD) chemotherapy. The low toxicity profile, reduced likelihood of inducing acquired therapeutic resistance, and low cost of MCT render it an attractive chemotherapeutic regimen option. One of the most prominent aspects of MCT is its anti-angiogenesis effects. It has been shown to stimulate the expression of anti-angiogenic molecules, thereby inhibiting angiogenesis. In addition, MCT has been shown to decrease the regulatory T-cell population and promote anti-tumor immune response through inducing dendritic cell maturation and increasing the number of cytotoxic T-cells. Combination therapies utilizing MCT along with oncolytic virotherapy, radiotherapy or other chemotherapeutic regimens have been studied extensively. This review provides an overview of the current status of MCT research and the established mechanisms of action of MCT treatment and also offers insights into potential avenues of development for MCT in the future.

Activity and safety of KEES - an oral multi-drug chemo-hormonal metronomic combination regimen in metastatic castration-resistant prostate cancer

BACKGROUND

Metastatic castration-resistant prostate cancer (mCRPC) remains a therapeutic challenge and evidence for late-line treatments in real-life is limited. The present study investigates the efficacy and safety of an oral metronomic chemo-hormonal regimen including cyclophosphamide, etoposide, estramustine, ketoconazole and prednisolone (KEES) administered in a consecutive biweekly schedule.

METHODS

A retrospective cohort study in two Swedish regions was conducted. Overall (OS) and progression-free survival (PFS), biochemical response rate (bRR) and toxicities were analyzed.

RESULTS

One hundred and twenty-three patients treated with KEES after initial treatment with at least a taxane or an androgen-receptor targeting agents (ARTA) were identified. Of those, 95 (77%) had received both agents and were the primary analysis population. Median (95% CI) OS and PFS in the pre-treated population were 12.3 (10.1-15.0) and 4.4 (3.8-5.5) months, respectively. Biochemical response, defined as ≥ 50% prostate-specific antigen (PSA) reduction, occurred in 26 patients (29%), and any PSA reduction in 59 (65%). PFS was independent of prior treatments used, and KEES seemed to be effective in late treatment lines. The bRR was higher compared to historical data of metronomic treatments in docetaxel and ARTA pre-treated populations. In multivariable analyses, performance status (PS) ≥ 2 and increasing alkaline phosphatase (ALP) predicted for worse OS. Nausea, fatigue, thromboembolic events and bone marrow suppression were the predominant toxicities.

CONCLUSIONS

KEES demonstrated meaningful efficacy in heavily pre-treated CRPC patients, especially those with PS 0-1 and lower baseline ALP, and had an acceptable toxicity profile.

Metronomic Chemotherapy for Advanced Prostate Cancer: A Literature Review

Metastatic castration-resistant prostate cancer (mCRPC) is the ultimately lethal form of prostate cancer. Docetaxel chemotherapy was the first life-prolonging treatment for mCRPC; however, the standard maximally tolerated dose (MTD) docetaxel regimen is often not considered for patients with mCRPC who are older and/or frail due to its toxicity. Low-dose metronomic chemotherapy (LDMC) is the frequent administration of typically oral and off-patent chemotherapeutics at low doses, which is associated with a superior safety profile and higher tolerability than MTD chemotherapy. We conducted a systematic literature review using the PUBMED, EMBASE, and MEDLINE electronic databases to identify clinical studies that examined the impact of LDMC on patients with advanced prostate cancer. The search identified 30 reports that retrospectively or prospectively investigated LDMC, 29 of which focused on mCRPC. Cyclophosphamide was the most commonly used agent integrated into 27/30 (90%) of LDMC regimens. LDMC resulted in a clinical benefit rate of 56.8 ± 24.5% across all studies. Overall, there were only a few non-hematological grade 3 or 4 adverse events reported. As such, LDMC is a well-tolerated treatment option for patients with mCRPC, including those who are older and frail. Furthermore, LDMC is considered more affordable than conventional mCRPC therapies. However, prospective phase III trials are needed to further characterize the efficacy and safety of LDMC in mCRPC before its use in practice.