Metronomic Cyclophosphamide Research Articles

Metronomic low dose cyclophosphamide in combination with a DNA methyltransferase inhibitor limits tumor growth in murine triple negative breast cancer

Abstract Many breast cancers are treated with therapies that target herceptin, estrogen, or progesterone receptors; however, for triple-negative breast cancers (TNBC) that lack these receptors, treatment options are limited, and prognosis is often unfavorable. The goal of this study is to design a therapeutic intervention that can elicit an effective immune response against the tumor and instill immunological memory to eradicate primary and metastatic lesions. Guadecitabine (Guad) is a second-generation DNA methyltransferase inhibitor (DMNTi) that has been reported to have several antitumor properties such as increased antigenicity and depletion of myeloid-derived suppressor cells (MDSC’s). Cyclophosphamide is a FDA approved chemotherapy that has been shown, when given as a low-dose treatment, to selectively deplete regulatory T-cells (T-regs). Both MDSCs and T-regs suppress antitumor immunity. We hypothesize that the combination of Guad and Cyp will synergize and promote anticancer immunity through increased expression of de novo tumor antigens and depletion of MDSCs and T-regs in a low-dose setting. To test this hypothesis, BALB/c mice were challenged with murine TNBC 4T1 tumor cells and the 4T1-bearing mice were administered low-dose Guad and Cyp daily for ten consecutive days. This experiment showed a degree of synergy between Guad and Cyp with the dual therapy reducing tumor burden to a greater extent than either monotherapy.

Abstract B54: Single-cell analytics in claudin-low TNBC reveals immunostimulatory effects of low-dose metronomic cyclophosphamide treatment

Abstract Breast cancer is a heterogeneous disease. It can be classified into at least five subtypes: luminal A and B, normal breast like, Her2 positive, basal like, and claudin low. Among these, claudin-low tumors have relatively poor prognosis. These tumors are characterized by the low expression of cell-cell junction proteins along with an enrichment of EMT markers. They are more aggressive and the rate of response to primary chemotherapy is around 32%. Initial data have shown that murine p53 null claudin-low tumors are only sensitive to cyclophosphamide treatment. Cyclophosphamide (CTX) is a chemotherapy drug that has been used in lymphoma, leukemia, and some solid tumors. At low and continuous doses, it shows immunostimulatory properties. In this study we describe the implementation of a novel combination treatment for claudin-low TNBC as informed by combined scRNA-seq and V(D)J seq. Immune profiles of a murine claudin-low tumor model (T12) shows heavy infiltration by tumor-associated macrophages (TAMs) pretreatment. Initial data in T12 tumors also suggest that CTX induces CD4+ and CD8+ T-cell homing to the primary tumor. Wild-type Balb/c mice implanted with T12 tumors respond favorably to CTX treatment as compared to T cell-deficient NSG mice. We combined 5´ scRNA-seq with V(D)J seq to gain an insight into how immune cell subpopulations change during the course of treatment. Combining tSNE plots for untreated and treated tumors revealed the emergence of new transcriptionally distinct populations in the CTX treated group, which included six T cell subpopulations. Projection of T cells along pseudotime using Monocle3 revealed a shift from naive CD8+ and CD4+ T cells to a terminal effector CD8+ T-cell phenotype and CD4+ effector memory cells in treated tumors while untreated tumors have higher numbers of exhausted Tigit+ CD8+ T cells and Tregs. V(D)J analysis revealed higher numbers of unique TCRs in CTX-treated tumors and greater clonal expansion of T cells. However, we noted a persistence of TAMs in our model even after treatment as well as high recurrence rates upon cessation of treatment. We then examined markers specific to the TAM subsets in the treated and untreated tumors and observed that TAMs expressed high levels of Csf1r. A chow containing PLX3397(iCSF1R) was employed to inhibit CSF1R, a macrophage differentiation/recruitment factor. Combination treatment with CTX and the iCSF1R chow lead to long-term regression of T12 tumors. Rechallenging these mice resulted in much slower tumor growth, indicating the formation of T cell memory. scRNA-seq and V(D)J seq is being performed on these samples to identify the clonal dynamics of effector T cells that assist in this striking regression. We hypothesize that CTX treatment can sensitize T12 primary tumors to T cell-mediated apoptosis, and that TAMS can suppress T-cell function and promote chemoresistance. Furthermore, depleting these TAMs in combination with CTX treatment may lead to long-term durable regression of both the primary tumor and metastases. Citation Format: Swarnima Singh, Ying-Wooi Wan, Nigel Lee, Se-Jin Kim, Zhandong Liu, Charles M. Perou, Xiang Zhang, Jeffrey Rosen. Single-cell analytics in claudin-low TNBC reveals immunostimulatory effects of low-dose metronomic cyclophosphamide treatment [abstract]. In: Proceedings of the AACR Special Conference on Tumor Immunology and Immunotherapy; 2019 Nov 17-20; Boston, MA. Philadelphia (PA): AACR; Cancer Immunol Res 2020;8(3 Suppl):Abstract nr B54.

Durable response to tamoxifen and metronomic cyclophosphamide in a patient with metastatic estrogen receptor-positive uterine leiomyosarcoma

Uterine leiomyosarcoma is a rare uterine malignancy, but the most common type of uterine sarcoma, in which a considerable proportion of tumors express estrogen/progesterone hormone receptors. We report a case of estrogen receptor-positive uterine leiomyosarcoma with a durable response to a combination of tamoxifen and metronomic cyclophosphamide. The current landscape and potential systemic treatment for uterine leiomyosarcoma were also briefly reviewed.

Bevacizumab in combination with metronomic oral cyclophosphamide: an effective and well-tolerated treatment for patients with recurrent ovarian cancer

Bevacizumab in combination with metronomic oral cyclophosphamide: an effective and well-tolerated treatment for patients with recurrent ovarian cancer

Low-dose Metronomic Cyclophosphamide Therapy as Postoperative Adjuvant Chemotherapy in 28 Dogs with Malignant Tumors

Low-dose Metronomic Cyclophosphamide Therapy as Postoperative Adjuvant Chemotherapy in 28 Dogs with Malignant Tumors

A Phase 1b Study Evaluating the Safety, Tolerability, and Immunogenicity of CMB305, a Lentiviral-Based Prime-Boost Vaccine Regimen, in Patients with Locally Advanced, Relapsed, or Metastatic Cancer Expressing NY-ESO-1

ABSTRACT Preclinical data suggest that a “prime-boost” vaccine regimen using a target-expressing lentiviral vector for priming, followed by a recombinant protein boost, may be effective against cancer; however, this strategy has not been evaluated in a clinical setting. CMB305 is a prime-boost vaccine designed to induce a broad anti-NY-ESO-1 immune response. It is composed of LV305, which is an NY-ESO-1 expressing lentiviral vector, and G305, a recombinant adjuvanted NY-ESO-1 protein. This multicenter phase 1b, first-in-human trial evaluated CMB305 in patients with NY-ESO-1 expressing solid tumors. Safety was examined in a 3 + 3 dose-escalation design, followed by an expansion with CMB305 alone or in a combination with either oral metronomic cyclophosphamide or intratumoral injections of a toll-like receptor agonist (glucopyranosyl lipid A). Of the 79 patients who enrolled, 81.0% had sarcomas, 86.1% had metastatic disease, and 57.0% had progressive disease at study entry. The most common adverse events were fatigue (34.2%), nausea (26.6%), and injection-site pain (24.1%). In patients with soft tissue sarcomas, a disease control rate of 61.9% and an overall survival of 26.2 months (95% CI, 22.1–NA) were observed. CMB305 induced anti-NY-ESO-1 antibody and T-cell responses in 62.9% and 47.4% of patients, respectively. This is the first trial to test a prime-boost vaccine regimen in patients with advanced cancer. This approach is feasible, can be delivered safely, and with evidence of immune response as well as suggestion of clinical benefit.

Low-dose metronomic cyclophosphamide complements the actions of an intratumoral C-class CpG TLR9 agonist to potentiate innate immunity and drive potent T cell-mediated anti-tumor responses.

The synthetic oligonucleotide SD-101 is a potent and specific agonist for toll-like receptor 9. Intratumoral injection of SD-101 induces significant anti-tumor immunity in preclinical and clinical studies, especially when combined with PD-1 blockade. To build upon this strategy, we studied the enhancement of SD-101 activities by combination with low-dose cyclophosphamide, a well-characterized agent with potentially complementary activities. In multiple mouse tumor models, we demonstrate substantial anti-tumor activity of the combination, compared to each single agent. Combination therapy generated CD8+ T cell dependent immunity leading to rejection of both non-injected and injected tumors and long-term survival, even in very large tumors. Mechanistic studies encompassing global gene expression changes and characterization of immune cell infiltrates show the rapid, sequential induction of innate and adaptive responses and identify discrete contributions of SD-101 and cyclophosphamide. Importantly, these changes were prominent in tumors not injected directly with SD-101. Combination treatment resulted in creation of a permissive environment for a systemic anti-tumor immune response, including a reduction of intratumoral regulatory T cells (Tregs) and an increase in “M1” versus “M2” tumor-associated macrophage (TAM) phenotypes. Additionally, we observed increased immunogenic cell death as well as antigen processing in response to combination treatment.

Metronomic cyclophosphamide induces regulatory T cells depletion and PSA-specific T cells reactivation in patients with biochemical recurrent prostate cancer.

Biochemical recurrence (BCR) occurs in up to 40% of prostate cancer patients after prostatectomy. In our study, we performed an immune monitoring study in 20 prostate cancer patients with BCR previously treated with metronomic cyclophosphamide (mCTX). We observed a decrease of regulatory T cells (Tregs) from 2 months and this was more pronounced after 6 months of mCTX treatment. This drop of Tregs was associated with increased level of activated HLADR+ CD45R0+ T cells in peripheral blood. Furthermore, a reactivation of Th1 polarized anti-PSA T-cell response was detected in BCR patients treated with mCTX. However, dendritic cell subsets counts and activation were not influenced by the treatment. In the clinical setting, we found that PSA level control was observed in 82% (9/11) of patients with a significant diminution of Tregs after mCTX compared to 33% (3/9) in patients without Tregs decrease. In addition, 30% (6/20) of patients previously treated with mCTX remained free for androgen deprivation therapy. In conclusion, Tregs diminution and immune activation associated with PSA level control occurred after mCTX in prostate cancer patients with BCR.

Programmed cell death 1 (PD-1) targeting in patients with advanced osteosarcomas: results from the PEMBROSARC study

PurposeThere are some lines of evidence suggesting a potential role of immunotherapy for treating patients with osteosarcomas. Patients and methodsThis was an open-label, multicentre, phase 2 study of pembrolizumab in combination with metronomic cyclophosphamide in patients with advanced osteosarcomas. All patients received 50 mg b.i.d. of cyclophosphamide one week on and one week off and 200 mg of intravenous pembrolizumab (every 3 weeks). There was a dual primary end-point, encompassing both the non-progression and objective responses at 6 months per Response Evaluation Criteria in Solid Tumours (RECIST), version 1.1. An objective response rate of 20% and/or a 6-month non-progression rate of 60% were determined as reasonable objectives for treatment with meaningful effect. Correlative studies of immune biomarkers were planned from the patients' tumour samples. ResultsBetween October 13 2015 and July 3 2017, 17 patients were included. Fifty were assessable for the efficacy end-point. Four patients experienced tumour shrinkage, resulting in a partial response (PR) in one patient (6.7%). The 6-month non-progression rate was 13.3% (95% confidence interval [CI]: 1.7–40.5). The most frequent adverse events were grade I or II nausea, anaemia, anorexia and fatigue. programmed death-ligand 1 (PD-L1) expression rate was low, observed in only 2 cases of 14 with available tumour material. The only patient who experienced PR had a PD-L1–negative tumour. ConclusionProgrammed cell death 1 (PD-1) inhibition has limited activity in osteosarcomas. Further studies investigating PD-1 inhibitor in combination with agents modulating the microenvironment are warranted. Trial registrationThis study is registered with ClinicalTrials.gov, number NCT02406781.

Metronomic chemotherapy with cyclophosphamide plus low dose of corticosteroids in advanced castration-resistant prostate cancer across the era of taxanes and new hormonal drugs.

The aim of our study is to investigate the efficacy of metronomic cyclophosphamide plus low dose of corticosteroids in advanced or metastatic castration-resistant prostate cancer (CRPC) before, between, and after standard chemotherapy, such as docetaxel and cabazitaxel, and new hormonal treatments, such as abiraterone and enzalutamide. A retrospective analysis was performed on 37 patients. Cyclophosphamide was given orally 50mg per day together with low dose of corticosteroids, namely dexametasone orally 1mg per day or prednisone 10mg per day. Seventeen patients (51%) showed a PSA decline≥ 50%. Median progression-free survival (PFS) and overall survival (OS) were 11 and 28months, respectively. Median PFS and OS in the subgroup of patients with a PSA decline ≥ 50% were 14 and 35months, respectively. Treatment was very well tolerated. We suggest that oral metronomic cyclophosphamide plus low dose of oral dexamethasone or prednisone may be a good and safe therapeutic option not only in those CRPC patients unfit for standard treatments but also in those heavily pre-treated patients.

Abstract 4993: The Kynurenine Pathway as a possible resistance mechanism to immunotherapy in sarcomas

Abstract Background: Sarcomas are heterogenous malignant mesenchymal neoplasms known to be particularly resistant to immunotherapy, which thus calls the interest of the elucidation of related resistance mechanisms. We recently demonstrated an increase in Kynurenine Pathway (KP) activity in the plasma of patients undergoing Pembrolizumab and metronomic cyclophosphamide. The KP has already been described to favor tolerance and immune escape through the degradation of L-Tryptophan and production of a series of metabolites including L-Kynurenine. While Indoleamine 2,3 dioxygenase (IDO1), a first rate-limiting enzyme of the KP still represents an attractive therapeutic target, the exact functional role of the KP upon immunotherapy has not yet been clearly elucidated. Methods: Using a preclinical syngeneic mouse model of sarcoma based on the inoculation of murine sarcoma MCA205 cell line, we investigated the modulation of the KP upon PDL1 blockade. Besides the evaluation of tumor growth and survival, intratumoral biopsy was performed and used for further gene expression analysis by RT-qPCR. More precisely, KP enzymes- and key cytokines-encoding genes were assessed. Using the same experimental setting on satellite mice, intratumoral microdialysis was performed on day 13 post-tumor inoculation and kynurenine contents were quantified within the tumoral microenvironment. Results: PDL1 blockade, using a specific anti-PDL1 antibody (provided by Genentech), exhibited a clear anti-tumoral effect associated with an intratumoral inflammatory cytokines signature driven by Ifng, Tnfa and Il2. Interestingly, Ifng level was significantly and positively associated with response to anti-PDL1. As regards to KP enzymes, a slight upregulation of the tryptophan-degrading enzymes Ido1 and Ido2 was detected while no changes were observed for Tdo2. An increase of kynurenine-degrading enzymes, including Kmo (encoding for Kynurenine monoamine oxygenase) and Kynu (encoding for kynureninase), was also detected thereby suggesting that PDL1 blockade favors Kynurenine degradation as a possible compensatory mechanism. These results were confirmed by intratumoral microdialysis in the satellite study. Indeed, anti-PDL1 was able to decrease the Kynurenine to Tryptophan ratio(Kyn / Trp) while increasing intratumoral production of kynurenines catabolites. In conclusion, this new set of data on a preclinical sarcoma model highlights for the first time that PDL1 blockade deeply modulates the Kynurenine Pathway with an effect not exclusively associated to the upper part of the pathway and thus warrants further investigation. Citation Format: Imane Nafia, Ariel Savina, Alban Bessede, Antoine ITALIANO. The Kynurenine Pathway as a possible resistance mechanism to immunotherapy in sarcomas [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 4993.

Abstract 533: The immune landscape in colon cancer and its changes after radiotherapy

Abstract Background: The TRANSLATE project started in 2016 to test the immune effects on circulating immune cells and cytokines of metronomic Cyclophosphamide (CTX), daily low-dose IL-2 administered every other week, and radiotherapy (RT). The rationale is based on self vaccination induced by RT, T cells expansion by IL-2 treatment and selective Tregs down regulation by low dose cyclophosphamide administration. Materials/Methods: Treatment consisted of CTX 50/mg tab daily continuously until progression or unacceptable toxicity, 8 Gy single fraction on one metastatic lesion given day 8 from CTX start and IL-2, 500.000 UI twice a day i.v. day 1 to 5 every other week, starting the day after RT. We enrolled patients with end-stage for colon, breast, kidney and prostate cancer. Analysis was performed at baseline, the day after RT, after 28 days from treatment start and at disease progression. Assay focused on Tregs, CD8+, NK, MDSC, CD3-PD1, IL-2, IL-4, IL-5, IL- 6, IL-10, IL-12, IL-13, IL-17a, TNFα, IFNγ, TGFβ. We report baseline and post-RT data separately in patients with colon cancer (CC) and other patients (non-CC). Results: We report data from 8 pts with left colon, 6 with breast, 2 with kidney and 3 with prostate cancer. At baseline, cytokine expression was similar in CC and non-CC except IFNγ and IL-13, both less represented in CC. After RT, TNFα increased in both groups, but more evidently in CC. A clear increase in IL-10 and IFNγ occurred only in non-CC, while IL-2 increased only in CC. Cumulatively, CC and non-CC reacted differently to RT in terms of positive or negative changes of the analyzed cytokines. On the contrary, we did not observe clear differences in immune cells between CC and non-CC neither at baseline nor after RT. Discussion: The limited number of patients reduced the interpretation of the study. The differences observed are numerical, but not statistically significant. Colon cancer shows some peculiarities, including the low IL-13 and IFNγ value and a different response to RT. Further analyses investigations are in progress. Citation Format: Cristiana Lo Nigro, Dario Sangiolo, Vincenzo Ricci, Ornella Garrone, Andrea Abbona, Antonella Falletta, Anna Merlotti, Chiara Varamo, Massimo Aglietta, Loretta Gammaitoni, Oscar Bertetto, Marco Merlano. The immune landscape in colon cancer and its changes after radiotherapy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 533.

Pembrolizumab and Oral Metronomic Cyclophosphamide in Patients With Chest Wall Breast Cancer

Pembrolizumab and Oral Metronomic Cyclophosphamide in Patients With Chest Wall Breast Cancer

A phase II trial of pembrolizumab in combination with bevacizumab and oral metronomic cyclophosphamide for recurrent epithelial ovarian, fallopian tube or primary peritoneal cancer

A phase II trial of pembrolizumab in combination with bevacizumab and oral metronomic cyclophosphamide for recurrent epithelial ovarian, fallopian tube or primary peritoneal cancer

Phase II trial of metronomic capecitabine and cyclophosphamide with lapatinib and trastuzumab in patients with HER2-positive metastatic breast cancer.

e12508 Background: Metronomic chemotherapy is an emerging paradigm of cancer therapy in which low doses of chemotherapy are delivered at frequent intervals. Activity in patients with metastatic breast cancer (MBC) has been demonstrated in several phase II clinical trials. Methods: We proposed a regimen with metronomic chemotherapy and dual HER2 inhibition in HER2 positive patients with MBC. We hypothesized that this regimen will be highly active in MBC and have a favorable toxicity profile. Patients were treated on a 21-day cycle with capecitabine 1500mg PO daily, cyclophosphamide 50mg daily, lapatinib 1000mg PO daily and trastuzumab 6mg/kg IV once per 21-day cycle. This regimen was continued until disease progression or unacceptable toxicity. Primary endpoint was progression free survival (PFS). Secondary endpoints were overall response rate (ORR), clinical benefit rate (CBR), overall survival (OS), and safety and tolerability of this regimen. Eligibility criteria were patients 18 years of age and older who had histologically confirmed HER2-positive metastatic breast cancer with prior trastuzumab use in the adjuvant or metastatic setting with no more than two prior regimens for MBC. Results: Ten patients were accrued from Jan 2014-Oct 2016. Median age was 52 (range 38 - 79) years. Median number of chemotherapy regimens for metastatic disease was 0.5 (range 0-2). Median PFS was 13.7 (95% CI: 2.6, 16.6) months. Median OS was 29.6 (95% CI: 11.8, 60.5+) months. ORR was 30%, and CBR was 70%. Grade 3 or 4 toxicities were identified in 6 patients. The most common toxicities of any grade were fatigue (100%), diarrhea (80%), anemia, neutropenia, ALT increase, nausea and hand-foot syndrome 50% each. One patient achieved CR for over 3 years and continues on treatment at time of this report. 8 patients progressed and 1 patient withdrew from study without response evaluation. The trial was closed due to lack of accrual. Conclusions: The proposed regimen of metronomic capecitabine and cyclophosphamide with lapatinib and trastuzumab appears to be active in patients with HER2 positive MBC but with significant toxicity. Clinical trial information: NCT01873833.

Activity and safety of metronomic cyclophosphamide in the modern era of metastatic castration-resistant prostate cancer.

To evaluate activity of metronomic cyclophosphamide (mCTX) in heavily pretreated metastatic castration-resistant prostate cancer (mCRPC) patients. We retrospectively evaluated a consecutive series of 74 mCRPC patients treated with at least one new agent after docetaxel failure, who received once-daily oral mCTX treatment at a fixed dose of 50mg. The treatment was well tolerated. Sixteen percent of the patients experienced a major biochemical response. Median progression-free survival was 4.0months, and median overall survival was 8.1months. In the modern context of mCRPC, mCTX may represent a valuable and inexpensive alternative to new agents, which have shown similar activity in heavily pretreated patients.

Autologous Dendritic Cells and Metronomic Cyclophosphamide for Relapsed High-Grade Gliomas in Children and Adolescents

Autologous Dendritic Cells and Metronomic Cyclophosphamide for Relapsed High-Grade Gliomas in Children and Adolescents

Next generation sequencing driven successful combined treatment with laparoscopic surgery and immunotherapy for relapsed stage IVB cervical and synchronous stage IV lung cancer.

Background: The treatment of patients with multiple synchronous tumors is challenging and complex. The use of next generation sequencing (NGS) may help in identification of germline mutations in genes involved in a common etiology for both tumors thus allowing a common effective therapeutic strategy. Patients and Methods: We describe the unexpected positive results obtained in a young woman with relapsed chemo-resistant stage IVB cervical and synchronous stage IV lung cancer, who underwent an interdisciplinary approach including palliative surgery with laparoscopic total pelvic exenteratio followed by a chemo-immunotherapy protocol with the anti-Programmed Death (PD)-1 antibody nivolumab plus metronomic cyclophosphamide. The treatment choice was based on tumor PD-Ligand 1 assessment and NGS analysis for the identification of potential treatment targets. Outcomes included tumor objective response and patient-centered outcomes (pain, performance status and overall quality of life). Results: Laparoscopic surgery obtained an immediate symptom control and allowed the early start of medical treatment. One month after combined therapy start the patient achieved a significant improvement in performance status, pain, overall Quality of life and after 3 months she resumed working. After 3 and 6 months of treatment we observed an objective dimensional and metabolic response. Currently, after 24 months (and 48 cycles of nivolumab) the patient is continuing to benefit from treatment: she is in complete remission, with good performance status and she is working and leading a self-dependent life. Conclusion: Our study strongly affirms the efficacy of an interdisciplinary approach including surgical and innovative medical strategies based on immunotherapy in patients with advanced chemo-resistant synchronous cervical and lung cancer. The present findings support the use of NGS to drive a targeted rational treatment especially in heavily pre-treated patients.

Personalized use of metronomic cyclophosphamide for DNA repair deficient castration-resistant prostate cancer: A phase II trial.

TPS346 Background: There is a continued need to identify novel targets for the treatment of metastatic, castration-resistant prostate cancer (mCRPC). DNA damage repair (DDR) aberrations are emerging as such a target: 20%-30% of mCRPCs harbor DDR gene aberrations, rendering tumors particularly sensitive to DNA damaging agents and poly ADP-ribose polymerase inhibitor (PARPi) therapy. 88% of men with DDR deficient mCRPC responded to the PARPi olaparib in a phase II trial, whereas in unselected mCRPC patients the metronomic use of the DNA damaging agent cyclophosphamide (CPA) resulted in response rates of 25-60%. Intriguingly, in randomized phase II trials of unselected ovarian and triple-negative breast cancer (ie tumor types enriched for DDR defects), metronomic CPA alone was as active as metronomic CPA plus the PARPi veliparib. Based on this we hypothesize that DDR deficient mCRPC is particularly sensitive to metronomic CPA. To the best of our knowledge this is the first attempt to utilize metronomic CPA in a personalized manner. Our study has the potential to define metronomic CPA as an affordable and well-tolerated alternative to PARPi therapy in men with DDR deficient mCRPC. Methods: To study if metronomic CPA achieves a similar response rate (ie ≥85%) in DDR deficient mCRPC as seen with olaparib, men with mCRPC progressing after 1-2 lines of systemic therapy will undergo circulating tumor DNA based testing for BRCA1/2 or ATM aberrations. Patients with such aberrations will proceed with metronomic CPA (50 mg po daily). Primary endpoint: RECIST 1.1 and/or ≥50% PSA response rate at 12 weeks. Secondary endpoints include biochemical, radiological and clinical progression-free survival. Applying the Optimal Simon's Two-Stage design, and using a type I error rate of 0.05 and a power of 0.8, in the first stage we plan to enroll 14 patients. If there are ≤10 or fewer responses, the study will be stopped. Otherwise, another 19 patients will be accrued as part of the second stage.

Metronomic cyclophosphamide attenuates mTOR-mediated expansion of regulatory T cells, but does not impact clinical outcome in patients with metastatic renal cell cancer treated with everolimus

IntroductionMetastatic renal cell cancer (mRCC) patients have a median overall survival (mOS) of approximately 28 months. Until recently, mammalian target of rapamycin (mTOR) inhibition with everolimus was the standard second-line treatment regimen for mRCC patients, improving median progression-free survival (mPFS). Treatment with everolimus supports the expansion of immunosuppressive regulatory T cells (Tregs), which exert a negative effect on antitumor immune responses. In a phase 1 dose-escalation study, we have recently demonstrated that a low dose of 50 mg oral cyclophosphamide once daily can be safely combined with everolimus in mRCC patients and prevents the everolimus-induced increase in Tregs.Materials and methodsIn a multicenter phase 2 study, performed in patients with mRCC not amenable to or progressive on a vascular endothelial growth factor (VEGF)-receptor tyrosine kinase inhibitor (TKI) containing treatment regimen, we assessed whether the addition of this metronomic dosing schedule of cyclophosphamide to therapy with everolimus could result in an improvement of progression-free survival (PFS) after 4 months of treatment.ResultsThough results from this study confirmed that combination treatment effectively lowered circulating levels of Tregs, addition of cyclophosphamide did not improve the PFS rate at 4 months. For this reason, the study was abrogated at the predefined interim analysis.ConclusionAlthough the comprehensive immunomonitoring analysis performed in this study provides relevant information for the design of future immunotherapeutic approaches, the addition of metronomic cyclophosphamide to mRCC patients receiving everolimus cannot be recommended.