Immunomodulation by HDAC inhibition: Results from a phase Ib study with vorinostat and pembrolizumab in metastatic urothelial, renal, and prostate carcinoma patients

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Background: Immunosuppressive factors such as regulatory T cells (Tregs) and myeloid-derived suppressive cells (MDSCs) limit the efficacy of immunotherapies. Histone deacetylase (HDAC) inhibitors have been shown to have immunomodulatory effects. We have previously reported that HDAC inhibitors have synergistic antitumor effects in combination with PD-1 inhibition in tumor models by inhibiting the function of Tregs and MDSCs. Thus, we conducted a Phase Ib clinical study with the HDAC inhibitor vorinostat and the PD-1 inhibitor pembrolizumab in patients (pts) with metastatic urothelial, renal and prostate carcinoma. Methods: The primary objective was to evaluate the safety and tolerability of this combination strategy. The phase I portion consisted of two dose levels of vorinostat (100 and 200 mg, PO daily 2 weeks ON and one week OFF) and a fixed, standard dose of pembrolizumab (200 mg IV every 21 days). Patients were assigned to three cohorts: Cohort A (previously treated, anti-PD1/PD-L1 naïve urothelial and renal cancer pts = 15), Cohort B (previously treated, anti-PD1/PD-L1 resistant urothelial and renal cancer pts = 14), and Cohort C (prostate cancer pts = 14). Results: Dose levels 1 (4 enrolled, 3 evaluable) and 2 (4 enrolled, 3 evaluable) were completed without DLTs and 200 mg was the Phase II recommended dose for vorinostat. The most common resolved grade 3/4 toxicities were acute kidney injury (n = 1), anemia (n = 1), diarrhea (n = 1), and hypothyroidism (n = 1) in the dose expansion cohorts. We have enrolled 43 pts (37 evaluable) in the dose expansion cohorts. For Cohort A, B, and C the median PFS were 2.8 months, 5.2 months, and 3.5 months. Two PR were observed including the dose escalation phase. Two PCA pts have achieved undetectable PSA. We have performed several correlative studies including flow cytometry and gene expression analysis on peripheral blood mononuclear cells, PDL-1 staining and PSMA PET scans in a subset of pts. Conclusions: The results from this phase Ib suggest that the combination of vorinostat and pembrolizumab is relatively well tolerated and may be active in a subset of immune checkpoint resistant UC/RCC pts and immune checkpoint naïve PCA pts. Clinical trial information: NCT02619253.

Clinical course of patients with cisplatin (CDDP)-associated neuropathy compared to other neurotoxic chemotherapy

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Background: There are limited patient (pt) reported outcome data regarding CDDP neurotoxicity. Methods: CDDP-induced peripheral neuropathy was evaluated in pts with testicular cancer planning to receive CDDP (20 mg/m2/d for 5 days) for ≥ 3 cycles. Neurotoxicity was assessed with the EORTC QLQ-CIPN20 tool before each CDDP cycle and every 2-4 months after, out to 18 months. We compared these data to our studies evaluating pts receiving doxorubicin/cyclophosphamide (AC), paclitaxel and oxaliplatin. The total score of the EORTC QLQ-CIPN20, each of the three subscale scores and each individual item was computed following the standard scoring algorithm and converted to a 0-100 scale. Descriptive statistics and graphical plots were utilized. Results: 54 pts receiving CDDP (mean age 33 years) and 18 pts receiving AC were evaluated. Following completion of CDDP, neuropathy symptoms (sensory neuropathy score and numbness/tingling in toes/feet) worsened for about 6 months (consistent with the so-called “coasting phenomena”), similar to what had previously been seen with oxaliplatin (but different than what had been seen with paclitaxel). For CDDP pts, during therapy, numbness and tingling in fingers/hands were more prominent, than the same symptoms in the toes/feet. After therapy was completed, numbness, and tingling became more prominent in toes/feet, but improved in the fingers/hands. After stopping therapy, shooting/burning pain did not worsen in upper or lower extremities. During therapy, CDDP pts had less problems than had previously been seen with oxaliplatin or paclitaxel, maybe because of the younger ages of the CDDP pts. With AC, all of the CIPN-20 sensory neuropathy scores were better than was seen in the pts receiving CDDP and also in pts receiving paclitaxel and oxaliplatin in previous evaluations. Conclusions: CDDP-induced neuropathy is more similar to oxaliplatin-induced neuropathy than paclitaxel-induced neuropathy. AC chemotherapy pts do not have substantial changes in CIPN 20 scores, consistent with the CIPN 20 instrument being a measure of chemotherapy-induced neuropathy, as opposed to more general chemotherapy-induced toxicities. Clinical trial information: NCT02677727.