Best practices for the management of local-regional recurrent chordoma: a position paper by the Chordoma Global Consensus Group

Chordomas are rare, malignant bone tumors of the skull-base and axial skeleton. Until recently, there was no consensus among experts regarding appropriate clinical management of chordoma, resulting in inconsistent care and suboptimal outcomes for many patients. To address this shortcoming, the European Society of Medical Oncology (ESMO) and the Chordoma Foundation, the global chordoma patient advocacy group, convened a multi-disciplinary group of chordoma specialists to define by consensus evidence-based best practices for the optimal approach to chordoma. In January 2015, the first recommendations of this group were published, covering the management of primary and metastatic chordomas. Additional evidence and further discussion were needed to develop recommendations about the management of local-regional failures. Thus, ESMO and CF convened a second consensus group meeting in November 2015 to address the treatment of locally relapsed chordoma. This meeting involved over 60 specialists from Europe, the United States and Japan with expertise in treatment of patients with chordoma. The consensus achieved during that meeting is the subject of the present publication and complements the recommendations of the first position paper.

A randomized phase II study of flutamide with or without PSA-TRICOM in nonmetastatic castration-resistant prostate cancer (CRPC)

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Background: PSA-TRICOM is a vector-based, therapeutic cancer vaccine regimen consisting of recombinant poxviruses containing the transgenes for prostate-specific antigen (PSA) and 3 T-cell co-stimulatory molecules (TRICOM). A previous randomized, placebo-controlled phase II study demonstrated an 8.5-month improvement in median survival (25.1 months for PSA-TRICOM group vs. 16.6 months for control group) in men with metastatic CRPC.

Methods: This study is currently enrolling patients with non-metastatic CRPC on testosterone suppression therapy who have a rising PSA. Patients are stratified by PSA doubling time and randomized to androgen receptor antagonist alone (flutamide) or flutamide plus PSA-TRICOM. Flutamide is given at the standard dose of 400 mg TID while PSA-TRICOM is given by monthly subcutaneous injections. The primary endpoint of the study is time to treatment failure (TTF) which is defined as biochemical recurrence (PSA rise) or development of metastatic lesions on scans.

Results: The first 26 patients enrolled are evaluated in this analysis. For flutamide alone (n = 13), the median age at enrollment was 64.7 years and median Gleason Score was 8. For flutamide + PSA-TRICOM (n = 13), the median age at enrollment was 67.1 years and median Gleason score was 8. Median time to progression is 223 days for Fluatmide + PSA- TRICOM (range 70-638) vs. 85 days for Flutamide alone (56-372). Progression for 11/12 flutamide alone patients and 9/10 fluatmide + PSA-TRICOM patients has been by PSA rise only.

Conclusions: Preliminary evidence suggests improvement in time to treatment failure using combination of hormonal therapy with flutamide + PSA-TRICOM vaccine compared to fluatmide alone in patients with non-metastatic CRPC. This trial will continue to accrue a total of 62 patients and also will evaluate immunological responses.

No significant financial relationships to disclose.

Intraprostatic vaccine administration in patients with locally recurrent prostate cancer

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Background: PSA-TRICOM is a cancer vaccine consisting of recombinant poxviruses with transgenes for PSA and 3 T cell costimulatory molecules (TRICOM). A multicenter randomized vector controlled phase II study showed an 8.5 month improvement in median survival in men with metastatic CRPC. Preclinical studies showed intratumoral administration of TRICOM vaccines may improve anti-tumor outcomes. This study was intended to show safety of intraprostatic (i.p.) vaccine administration. 2° goals included immunologic and tumor response.

Methods: 21 pts were enrolled with locally recurrent prostate cancer after radiation into 5 cohorts and received initial vaccination with s.c. recombinant vaccinia (rV)-PSA-TRICOM and booster i.p. recombinant fowlpox (rF)-PSA-TRICOM. Cohorts 3-5 also received i.p. rF-GM-CSF. Cohort 5 received concurrent s.c. and i.p. boosters. Priming was given on day 1, and boosters were given on days 29, 57, and 85. Pts had pre- and post-treatment prostate biopsies. Tumor infiltrate was evaluated when adequate tissue was available. PBMCs were analyzed by ELISPOT for response to PSA and 3-color flow cytometry to characterize regulatory T cells (Treg) or effector T cells. Treg suppression function was assayed by suppression of the CD4+ effector T cell proliferation.

Results: Only 1 grade 3 toxicity occurred, a transient fever. Most common grade 2 adverse events for all doses were fever (14.5%) and injection-site reactions (21%). 15 of 21 pts had stable or improved PSA on study, and 16 of 21 pts had stable or improved PSA doubling time. Post-vaccination, 4 of 8 evaluable pts had immunological response by ELISPOT assay and 11 of 15 pts had decreased (n=8) or stable (n=3) Treg function. A paired t-test of 13 biopsies pre- and post- vaccination showed significant increases in immune infiltrates within tumors after vaccination. CD4+ cells increased from 1.3 → 13.1/high power field (hpf). CD8+ cells rose from 6.4 → 14/hpf.

Conclusions: I.p. administration of PSA-TRICOM is safe, feasible and can generate a substantial immunologic response. Improved PSA kinetics and intense post-vaccination immune infiltrates were seen in the majority of pts. Trials of i.p. PSA-TRICOM examining clinical endpoints are warranted.

No significant financial relationships to disclose.