Efficacy and safety of pembrolizumab in metastatic urothelial carcinoma: results from KEYNOTE-045 and KEYNOTE-052 after up to 5 years of follow-up

BACKGROUND

Immune checkpoint inhibitors are a standard therapy in metastatic urothelial carcinoma (UC). Long-term follow-up is necessary to confirm durability of response and identify further safety concerns.

PATIENTS AND METHODS

In KEYNOTE-045, patients with metastatic UC that progressed on platinum-containing chemotherapy were randomly assigned 1:1 to receive pembrolizumab or investigator's choice of paclitaxel, docetaxel, or vinflunine. Primary endpoints were progression-free survival per RECIST version 1.1 by blinded independent central review (BICR) and overall survival. In KEYNOTE-052, cisplatin-ineligible patients with metastatic UC received first-line pembrolizumab. The primary endpoint was objective response rate per RECIST version 1.1 by BICR.

RESULTS

A total of 542 patients (pembrolizumab, n = 270; chemotherapy, n = 272) were randomly assigned in KEYNOTE-045. The median follow-up was 62.9 months (range 58.6-70.9 months; data cut-off 1 October 2020). At 48 months, overall survival rates were 16.7% for pembrolizumab and 10.1% for chemotherapy; progression-free survival rates were 9.5% and 2.7%, respectively. The median duration of response (DOR) was 29.7 months (range 1.6+ to 60.5+ months) for pembrolizumab and 4.4 months (range 1.4+ to 63.1+ months) for chemotherapy; 36-month DOR rates were 44.4% and 28.3%, respectively. A total of 370 patients were enrolled in KEYNOTE-052. The median follow-up was 56.3 months (range 51.2-65.3 months; data cut-off 26 September 2020). The confirmed objective response rate was 28.9% (95% confidence interval 24.3-33.8), and the median DOR was 33.4 months (range 1.4+ to 60.7+ months); the 36-month DOR rate was 44.8%. Most treatment-related adverse events for pembrolizumab in either study were grade 1 or 2 and manageable, which is consistent with prior reports.

CONCLUSION

With ∼5 years of follow-up, pembrolizumab monotherapy continued to demonstrate durable efficacy with no new safety signals in patients with platinum-resistant metastatic UC and as first-line therapy in cisplatin-ineligible patients.

CLINICAL TRIAL REGISTRY AND ID

With ClinicalTrials.gov NCT02256436 (KEYNOTE-045); https://clinicaltrials.gov/ct2/show/NCT02256436 and NCT02335424 (KEYNOTE-052); https://clinicaltrials.gov/ct2/show/NCT02335424.

Abstract P2-09-03: Updated efficacy of first or second-line pembrolizumab (pembro) plus capecitabine (cape) in metastatic triple negative breast cancer (mTNBC) and correlations with baseline lymphocyte and naïve CD4+ T-cell count

Background: In mTNBC, anti-PD-1/L1 monotherapy is most effective when administered early in the course of disease, with recent trials demonstrating overall response rates (ORR) of 23-26% in the first-line setting and 5-6% in later lines. This may reflect iatrogenic lymphopenia from preceding cytotoxic chemotherapy. Furthermore, curative-intent chemotherapy is associated with prolonged suppression of naïve CD4+ cells, a T-cell subset that may play a critical role in the generation of de novo anti-tumor immune responses. We present the final clinical results of a pilot study evaluating the safety and efficacy of combining pembrolizumab plus standard-of-care capecitabine in the first/second-line mTNBC setting. We also explore potential associations between clinical benefit and lymphopenia, preceding chemotherapy, and absolute naïve CD4+ counts.

Methods: In a pilot study, we evaluated the tolerability and preliminary efficacy of concurrent pembro (200mg IV q21 day) plus investigator-selected 1st/2nd line paclitaxel (80mg/m2 IV weekly) or oral cape (2,000mg BID, weekly 1 on/1 off). The primary endpoint was tolerability, defined as the proportion of subjects receiving >6 weeks concurrent therapy without dose discontinuation with toxicities reported per CTCAE v4.0. The secondary endpoint was 12-week objective response rate (ORR) by RECIST1.1. Exploratory endpoints included peripheral blood cell enumeration by real-time flow cytometry and routine clinical laboratory. Naïve CD4+ cells were defined as CD45+ CD3+ TCRab+ CD4+ CD45RA+ CCR7+. Here, we report the results of the pilot phase of the cape cohort (NCT02734290).

Results: Twelve of 14 subjects were treated in the first-line setting. All subjects (14/14, 100%) tolerated cape+pembro for >6 weeks, with toxicities consistent with monotherapy cape experience (diarrhea: grade I-II 50%, grade III 7%; hand-foot: grade I-II 71%) that improved with dose-reduction as needed. At 12 weeks, the ORR was 6/14 (42.9%), and the clinical benefit rate (ORR + stable disease) was 8/14 (57.1%). Depressed absolute lymphocyte count at baseline (ALC<1.0/uL: 33% CBR; ALC≥1.0/uL: 75% CBR) and recent exposure to cytotoxic chemotherapy (<6 months: 33% CBR; >6 months: 75% CBR) were associated with reduced clinical benefit. By flow cytometry, subjects experiencing clinical benefit had higher baseline absolute naïve CD4+ counts (average 283 cells/uL v. 93 cells/uL, p=.069).

Conclusions: This study met the primary endpoint of safety for cape plus pembro in mTNBC, with encouraging clinical activity. These data are supportive of further studies evaluating combination chemotherapy plus anti-PD-1/L1 mTNBC. We observed greater clinical benefit in subjects with non-suppressed ALC, less exposure to recent chemo, and higher baseline naïve CD4+ counts, suggesting that iatrogenic immunosuppression can impair response to immune checkpoint therapy in mTNBC. These findings should be confirmed in ongoing randomized trials of immune checkpoint +/- chemotherapy in mTNBC, and should be considered in the design of future clinical trials.

Citation Format: Page DB, Pucilowska J, Bennetts L, Kim I, Sanchez K, Martel M, Conlin A, Moxon N, Mellinger S, Acheson A, Kemmer K, Mitri Z, Vuky J, Ahn J, Abaya C, Manigault T, Basho R, Urba WJ, McArthur HL. Updated efficacy of first or second-line pembrolizumab (pembro) plus capecitabine (cape) in metastatic triple negative breast cancer (mTNBC) and correlations with baseline lymphocyte and naïve CD4+ T-cell count [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P2-09-03.

The evaluation of flaxseed for hot flashes: Results of a randomized, controlled trial, NCCTG study N08C7

CRA9015

Background: Hot flashes are a common symptom during the menopause transition or following breast cancer treatment that can negatively impact the quality of life for many women. Preliminary data have suggested that flaxseed, a rich source of dietary lignans, may be a potentially effective treatment for hot flashes. Methods: A phase III randomized, placebo controlled trial was conducted to evaluate the efficacy of flaxseed in reducing hot flashes. Postmenopausal women were randomly assigned to a flaxseed bar (providing 410 mg of lignans) for 6 weeks vs a placebo bar. Participants completed daily prospective, self report hot flash diaries during the baseline week and then began eating one study bar per day for 6 weeks, while continuing to record their daily hot flashes. The intra-patient difference in hot flash activity between baseline and the last treatment week was the primary endpoint. Side effects of the bars were evaluated through self report and CTC assessment. Results: Between October and December 2009, 188 women were enrolled onto this trial. Mean hot flash scores were reduced by 4.9 units in the flaxseed group and 3.5 in the placebo group (p=0.29). In both groups, a little over a third of the women received a 50% reduction in their hot flash scores. Only one side effect was significantly different between groups, that being grade 1 pruritis, which was more common (7%) in the placebo group versus 1% in the flaxseed group. Both groups reported increased abdominal distension, flatulence, diarrhea and nausea. Adherence and ability to detect treatment assignment did not differ between groups. Conclusions: The results of this trial do not support the use of 410 mg of flaxseed lignans for the reduction of hot flashes. The gastrointestinal side effects seen in both groups were likely due to the fiber content in the flaxseed and placebo bars.

Phase II study of everolimus (E) with imatinib (IM) in patients with previously-treated renal carcinoma (RCC)

e16075

Background: Inhibitors of mTOR improve progression-free survival (PFS) in advanced RCC. We hypothesized that co-administration of the mTOR inhibitor E with an upstream receptor tyrosine kinase inhibitor could augment activity in advanced RCC. We chose to study IM due to its inhibition of PDGFR, a relevant target for RCC with potential activity at both the tumor cell and the pericyte. Methods: Eligible patients had metastatic or unresectable clear cell renal carcinoma, at least one prior systemic therapy, no prior mTOR inhibitor therapy, performance status 0–2, and measurable disease. Treatment consisted of E 2.5 mg p.o. daily and IM 600 mg p.o. daily, a dose determined from a phase I study in GIST. A two-stage design was employed to test for a 3-month PFS of ≥ 70% vs. ≤ 50%. Results: 19 subjects were evaluable for toxicity and 18 for response. Median age 65; number of prior systemic therapies 1:2:3+ (47%:32%:21%); prior sorafenib and/or sunitinib 89%; MSKCC prognostic categories favorable:intermediate:poor (42%:47%:11%). There were no objective responses. Best response was stable disease (67%) and progressive disease (33%). The 3-month PFS rate was 49% (95% C.I. 23%, 72%). The median PFS was 2.9 months (95% C.I. 1.9, 6.2) and the median overall survival was 14.4 months (95% C.I. 11.3, N.R.). Toxicities and lab abnormalities affecting >50% of subjects were: nausea, elevated creatinine, edema, anemia, hypocalcemia, fatigue, diarrhea, vomiting, and dyspnea, and leucopenia. Most common grade 3+ events were: fatigue (16%), pleural effusion (16%), edema (11%), and renal failure (11%). The study was closed after the first stage as the 3-month PFS did not meet continuation criteria. Conclusions: The combination of E 2.5 mg with IM 600 mg in previously-treated patients with advanced RCC did not meet the study-defined level of activity to warrant further investigation. The natural history assumptions for this pretreated RCC population may have been overly optimistic. While the observed PFS is comparable to that reported with E 10mg monotherapy, there appears to be no advantage to combination IM therapy and the incidence of adverse events is high. Further development of this regimen for RCC is not recommended.

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A phase II study of mammalian target of rapamycin (mTOR) inhibitor RAD001 plus imatinib mesylate (IM) in patients with previously treated advanced renal carcinoma (RCC)

15600

Background: The serine-threonine kinase mTOR is a valid target for RCC therapy with temsirolimus treatment resulting in improved overall survival in poor-risk patients (Hudes G et al., ASCO 2006). RAD001 is an oral inhibitor of mTOR which has demonstrated activity in RCC at 10mg/day (Amato R et al., ASCO 2006). IM is a tyrosine kinase inhibitor (TKI) of platelet-derived growth factor receptor (PDGFR), a target that may promote angiogenesis and growth of RCC. Combined mTOR and PDGFR inhibition with RAD001 and IM may achieve vertical blockade through the PI3K/AKT pathway. Methods: Eligibility: metastatic clear cell RCC, performance status (PS) 0–2, adequate organ function, and prior treatment with = 1 systemic therapy. Doses were based on a phase I study of the combination in GIST (Van Oosterom AT et al., ASCO 2005): RAD001 2.5 mg p.o. daily and IM 600 mg p.o. daily. Patients were reimaged every 6 weeks. This is a 2-stage phase II study to determine the 3-month progression-free rate. Results: 14 pts have been enrolled. Median age 66 years (51–79). 6 pts PS 0 and 8 pts PS 1. Median number of prior therapies 1.5 (1–4). 12 of 14 patients had prior TKI therapy. Prior therapies included sorafenib (11 pts), interferon (7), sunitinib (3), bevacizumab (2), erlotinib (1), panitumumab (1), high-dose IL-2 (1). Of 10 pts evaluable for the primary endpoint, 3 are progression-free = 3 months. Best response for 9 pts evaluable by RECIST: PR/CR 0, SD 7, PD 2. Most common adverse events in 11 evaluable patients include nausea (8), edema (7), increased creatinine (7), fatigue (7), transaminase elevation (6), thrombocytopenia (5), leukopenia (5), cough (5), diarrhea (5). Grade 3 adverse events include fatigue (3), LE edema, rash, pleural effusion, increased creatinine, abdominal pain, and thrombocytopenia (1 each). There were no grade 4 toxicities. Unique suspected RAD001 toxicities include grade 3 pneumonitis (1) and angioedema (1). Conclusions: The combination of RAD001 and IM has moderate toxicity. This is one of the first studies in RCC patients predominantly pretreated with a TKI. 3 month progression-free rate appears to be a clinically relevant endpoint in this population.

[Table: see text]

Phase I trial of 40-kd branched pegylated interferon alfa-2a for patients with advanced renal cell carcinoma

PURPOSE

Pegylated (40 kd) interferon alfa-2a (IFNalpha2a) (PEGASYS, Hoffman-La Roche, Nutley, NJ; PEG-IFN) is a modified form of recombinant human IFNalpha2a with sustained absorption and prolonged half-life after subcutaneous administration. A phase I study of PEG-IFN with pharmacokinetic and pharmacodynamic evaluations was conducted in previously untreated patients with advanced renal cell carcinoma (RCC).

PATIENTS AND METHODS

Twenty-seven patients were enrolled onto cohorts of three or six patients. PEG-IFN was administered on a weekly basis by subcutaneous injection. The dose was escalated from 180 microg/wk to a maximum of 540 microg/wk in 90-microg increments. Serial venous blood samples were drawn to assess concentrations of PEG-IFN and two immunologic surrogates, neopterin and 2'-5' oligoadenylate synthetase (OAS).

RESULTS

The maximum-tolerated dose was determined as 540 microg/wk, because two patients experienced dose-limiting toxicity within 28 days of starting treatment. One developed serum grade 3 ALT elevation, and a second developed grade 3 fatigue. Six patients were treated at 450 microg/wk without dose-limiting toxicity. Over the course of treatment, the side-effect profile was mostly mild to moderate in intensity. Adverse events included fatigue, fever, headache, myalgia, nausea, and decreased appetite. Five patients (19%) achieved a partial response. The mean maximum serum concentration increased from 5.0 to 27 ng/mL, and mean area under the curve increased from 247 to 2,981 ng/h/mL, with dose escalation from 180 microg/wk to 540 microg/wk. Serum concentration of PEG-IFN was sustained at close to peak during the dosing interval, and steady-state was achieved in approximately 5 weeks. The immunologic surrogates, neopterin and OAS, were induced at all doses with a sustained concentration profile similar to PEG-IFN.

CONCLUSION

PEG-IFN is a modified form of IFNalpha2a with distinct pharmacokinetic advantages and immunomodulatory and antitumor activity for patients with advanced RCC. A dose of 450 microg/wk by subcutaneous administration was determined as a suitable dose for further study. PEG-IFN is more convenient to administer than IFNalpha and has potential for increased efficacy, less toxicity, or both. The efficacy and toxicity of PEG-IFN will be further assessed in clinical trials and compared with IFNalpha.

Role of postchemotherapy adjunctive surgery in the management of patients with nonseminoma arising from the mediastinum

PURPOSE

To evaluate the role of postchemotherapy surgery in patients with nonseminomatous germ cell tumors arising from the anterior mediastinum.

PATIENTS AND METHODS

Thirty-two patients with nonseminoma arising from a mediastinal primary site were treated on a clinical trial at our center, and they underwent postchemotherapy surgery. The results of postchemotherapy surgical resection, frequency of viable tumor found during postchemotherapy surgery, and prognostic factors for survival were assessed.

RESULTS

Complete resection of all gross residual disease was achieved in 27 patients (84%). Histologic analysis of resected residua postchemotherapy revealed viable tumor in 66%, teratoma in 22%, and necrosis in 12% of the specimens. Viable tumor included embryonal carcinoma, choriocarcinoma, yolk sac carcinoma, seminoma, and teratoma with malignant transformation to nongerm cell histology (eg, sarcoma). Clinical characteristics associated with a shorter survival after surgery included the presence of viable tumor in a resected specimen (P =.003) and more than one site resected during surgery (P =.06). There were no statistically significant differences in survival for patients who underwent surgical resection with normal markers compared with patients with elevated serum tumor markers (P =.33). A trend toward shorter survival was found in patients with increasing tumor markers before surgery compared with patients with normal and declining serum tumor markers (P =.09).

CONCLUSION

Surgical resection of residual mass after chemotherapy plays an integral role in the management of patients with primary mediastinal nonseminoma. Teratoma and viable tumor were found in the majority of resected residua after chemotherapy. Because patients who undergo conventional salvage chemotherapy programs rarely achieve long-term disease-free status, selected patients with elevated markers after chemotherapy are considered candidates for surgical resection.

Cytokine therapy in renal cell cancer

Despite extensive investigations with many different treatment modalities, metastatic renal cell carcinoma (RCC) remains a disease highly resistant to systemic therapy. The outlook for patients with metastatic RCC is poor, with a 5-year survival rate of less than 10%. Late relapses after nephrectomy, prolonged stable disease in the absence of systemic therapy, and rare spontaneous regression are clinical observations that suggest host immune mechanisms could be important in regulating tumor growth. Interleukin-2 (IL-2) and interferon-alpha (IFN-alpha) have been extensively studied in advanced RCC with responses in the 10 to 20% range. Two randomized trials suggest that treatment with IFN-alpha compared with vinblastine or medroxyprogesterone results in a small improvement in survival. Prolonged responses with high-dose IL-2 is significant but is accompanied by formidable toxicity. Although the combination of IFN-alpha and IL-2 compared with monotherapy with IFN-alpha or IL-2 increases the response proportion, no improvement in survival could be demonstrated in a recent randomized trial. In addition, three randomized trials showed no survival benefit associated with IFN-alpha therapy given as adjuvant therapy following complete resection of locally advanced RCC. Small numbers of patients exhibit complete or partial responses to IFN-alpha and/or IL-2, but most patients do not respond and there are few long-term survivors. Clinical investigation of new agents and treatment programs to identify improved antitumor activity against metastases remain the highest priorities in this refractory disease.

Phase II trial of pyrazoloacridine in patients with cisplatin-refractory germ cell tumors

Thirteen patients with cisplatin-refractory germ cell tumors were treated on a Phase II trial with pyrazoloacridine. Pyrazoloacridine was given intravenously at 600 mg/m2 every three weeks. The median nadir leucocyte count was 2.5 cells/mm3, hemoglobin was 10.8 g/dl, and platelet count was 126,000 cells/m3. None of the thirteen evaluable patients achieved a major response. Pyrazoloacridine is not efficacious in the treatment of cisplatin-refractory germ cell tumors.