Cyclin-dependent kinase 4 and 6 (CDK4/6) inhibitors: existing and emerging differences.

The cyclin-dependent kinase 4 and 6 (CDK4/6) inhibitors palbociclib, ribociclib, and abemaciclib are standard-of-care therapy for hormone receptor-positive advanced or metastatic breast cancer, based on randomized trials showing improved progression-free survival for all 3 drugs and overall survival for ribociclib and abemaciclib. Results in early breast cancer are discordant, with sustained improvement in invasive disease-free survival demonstrated for abemaciclib but not other CDK4/6 inhibitors to date. We review nonclinical studies exploring mechanistic differences between the drugs, the impact of continuous dosing on treatment effect, and translational research into potential resistance mechanisms and prognostic and predictive markers. We focus particularly on how emerging findings may help us understand similarities and differences between the available CDK4/6 inhibitors. Even at late-stage clinical development, there remains much to learn about how agents in this class exert their varying effects.

Impact of primary tumour location on efficacy of bevacizumab plus chemotherapy in metastatic colorectal cancer.

BACKGROUND: Two first-line (1L) bevacizumab trials showed the prognostic value of primary tumour location in metastatic colorectal cancer (mCRC). In this retrospective subgroup analysis, further analysis of the predictive effect of bevacizumab is presented. METHODS: Patients with sidedness information from two randomised phase III studies of bevacizumab + chemotherapy (CT) vs CT as 1L mCRC treatment were analysed retrospectively. RESULTS: Sidedness was determined in 1590 (27% right and 73% left) of 2214 patients. Progression-free survival was improved with bevacizumab + CT vs CT in right-sided (HR = 0.75; 95% CI 0.61, 0.93; p = 0.008) and left-sided (HR = 0.76; 95% CI 0.67, 0.86; p < 0.001) mCRC (pooled analysis). Similarly, overall survival was numerically improved with bevacizumab + CT vs CT in right-sided mCRC (HR = 0.82; 95% CI 0.65, 1.03; p = 0.085), and significantly improved in left-sided mCRC (HR = 0.85; 95% CI 0.74, 0.98; p = 0.028). CONCLUSIONS: This analysis indicates that the effect of bevacizumab is independent of tumour location in mCRC.

Bevacizumab Prevents Brain Metastases Formation in Lung Adenocarcinoma.

Patients with nonsquamous non-small cell lung cancer (nsNSCLC; largely lung adenocarcinoma) are at high risk of developing brain metastases. Preclinical data suggested that anti-VEGF-A therapy may prevent the formation of nsNSCLC brain metastases. Whether non-brain metastases are also prevented, and whether bevacizumab shows a brain metastases-preventive activity in cancer patients is unknown. Data of one nsNSCLC (stage IIIB/IV, AVAiL) and two breast cancer bevacizumab trials (HER2 negative, AVADO; HER2 positive, AVEREL) were retrospectively analyzed regarding the frequency of the brain versus other organs being the site of first relapse. For animal studies, the outgrowth of PC14-PE6 lung adenocarcinoma cells to brain macrometastases in mice was measured by intravital imaging: under control IgG (25 mg/kg) treatment, or varying doses of bevacizumab (25 mg/kg, 2.5 mg/kg, 0.25 mg/kg). Brain metastases as site of first relapse were significantly less frequent in the bevacizumab arm of the AVAiL trial (HR = 0.36, P < 0.001). In AVADO and AVEREL, no significant difference was seen. In mice, bevacizumab treatment led to secondary regressions of non-brain macrometastases, but did not reduce their total incidence, and did not improve survival. In a brain-seeking nsNSCLC metastasis model, treatment with bevacizumab inhibited brain metastases formation, which resulted in improved overall survival. In summary, bevacizumab has the potential to prevent brain metastases in nsNSCLC, but no preventive activity could be detected outside the brain. These data indicate that anti-VEGF-A agents might be particularly relevant for those stage III nsNSCLC patients who are at high risk to develop future brain metastases. Mol Cancer Ther; 15(4); 702-10. ©2016 AACR.

Bevacizumab plus chemotherapy versus chemotherapy alone as second-line treatment for patients with HER2-negative locally recurrent or metastatic breast cancer after first-line treatment with bevacizumab plus chemotherapy (TANIA): an open-label, randomised phase 3 trial.

BACKGROUND: Combining bevacizumab with first-line or second-line chemotherapy improves progression-free survival in HER2-negative locally recurrent or metastatic breast cancer. We assessed the efficacy and safety of further bevacizumab therapy in patients with locally recurrent or metastatic breast cancer whose disease had progressed after treatment with bevacizumab plus chemotherapy. METHODS: In this open-label, randomised, phase 3 trial, we recruited patients who had HER2-negative locally recurrent or metastatic breast cancer that had progressed after receiving 12 weeks or more of first-line bevacizumab plus chemotherapy from 118 centres in 12 countries. Patients were randomly assigned (1:1) by use of a central interactive voice response system using a block randomisation schedule (block size four) stratified by hormone receptor status, first-line progression-free survival, selected chemotherapy, and lactate dehydrogenase concentration, to receive second-line single-agent chemotherapy either alone or with bevacizumab (15 mg/kg every 3 weeks or 10 mg/kg every 2 weeks). Second-line therapy was continued until disease progression, unacceptable toxicity, or consent withdrawal. At progression, patients randomly assigned to chemotherapy alone received third-line chemotherapy without bevacizumab; those randomly assigned to bevacizumab continued bevacizumab with third-line chemotherapy. The primary endpoint was progression-free survival from randomisation to second-line progression or death in the intention-to-treat population. This trial is ongoing, and registered with ClinicalTrials.gov, number NCT01250379. FINDINGS: Between Feb 17, 2011, and April 3, 2013, 494 patients were randomly assigned to treatment (247 in each group). The median duration of follow-up at the time of this prespecified primary progression-free survival analysis was 15·9 months (IQR 9·1-21·7) in the chemotherapy-alone group and 16·1 months (10·6-22·7) in the combination group. Progression-free survival was significantly longer for those patients treated with bevacizumab plus chemotherapy than for those with chemotherapy alone (median: 6·3 months [95% CI 5·4-7·2] vs 4·2 months [3·9-4·7], respectively, stratified hazard ratio [HR] 0·75 [95% CI 0·61-0·93], two-sided stratified log-rank p=0·0068). The most common grade 3 or more adverse events were hypertension (33 [13%] of 245 patients receiving bevacizumab plus chemotherapy vs 17 [7%] of 238 patients receiving chemotherapy alone), neutropenia (29 [12%] vs 20 [8%]), and hand-foot syndrome (27 [11%] vs 25 [11%]). Grade 3 proteinuria occurred in 17 (7%) of 245 patients receiving combination therapy and one (<1%) of 238 patients receiving chemotherapy alone. Serious adverse events were reported in 61 (25%) of 245 patients receiving bevacizumab plus chemotherapy versus 44 (18%) of 238 patients receiving chemotherapy alone. INTERPRETATION: These results suggest that continued VEGF inhibition with further bevacizumab is a valid treatment option for patients with locally recurrent or metastatic HER2-negative breast cancer whose disease was stabilised or responded to first-line bevacizumab with chemotherapy. FUNDING: F Hoffmann-La Roche.

Maintenance capecitabine and bevacizumab versus bevacizumab alone after initial first-line bevacizumab and docetaxel for patients with HER2-negative metastatic breast cancer (IMELDA): a randomised, open-label, phase 3 trial.

BACKGROUND: Longer duration of first-line chemotherapy for patients with metastatic breast cancer is associated with prolonged overall survival and improved progression-free survival. We investigated capecitabine added to maintenance bevacizumab after initial treatment with bevacizumab and docetaxel in this setting. METHODS: We did this open-label randomised phase 3 trial at 54 hospitals in Brazil, China, Egypt, France, Hong Kong, India, Italy, Poland, Spain, and Turkey. We enrolled patients with HER2-negative measurable metastatic breast cancer; each received three to six cycles of first-line bevacizumab (15 mg/kg) and docetaxel (75-100 mg/m(2)) every 3 weeks. Progression-free patients were randomly assigned with an interactive voice-response system by block (size four) randomisation (1:1) to receive either bevacizumab and capecitabine or bevacizumab only (bevacizumab 15 mg/kg on day 1; capecitabine 1000 mg/m(2) twice per day on days 1-14, every 3 weeks) until progression, stratified by oestrogen receptor status (positive vs negative), visceral metastases (present vs absent), response status (stable disease vs response vs non-measurable), and lactate dehydrogenase concentration (≤1·5 vs >1·5 × upper limit of normal). Neither patients nor investigators were masked to allocation. The primary endpoint was progression-free survival (from randomisation) in the intention-to-treat population. This trial is registered with ClinicalTrials.gov, NCT00929240. FINDINGS: Between July 16, 2009, and March 7, 2011 (when enrolment was prematurely terminated), 284 patients received initial bevacizumab and docetaxel; 185 (65%) were randomly assigned (91 to bevacizumab and capecitabine versus 94 to bevacizumab only). Progression-free survival was significantly longer in the bevacizumab and capecitabine group than in the bevacizumab only group (median 11·9 months [95% CI 9·8-15·4] vs 4·3 months [3·9-6·8]; stratified hazard ratio 0·38 [95% CI 0·27-0·55]; two-sided log-rank p<0·0001), as was overall survival (median 39·0 months [95% CI 32·3-not reached] vs 23·7 months [18·5-31·7]; stratified HR 0·43 [95% CI 0·26-0·69]; two-sided log-rank p=0·0003). Results for time to progression were consistent with those for progression-free survival. 78 (86%) patients in the bevacizumab and capecitabine group and 72 (77%) in the bevacizumab only group had an objective response. Clinical benefit was recorded in 92 (98%) patients in the bevacizumab alone group and 90 (99%) in the bevacizumab and capecitabine group. Mean change from baseline in global health score did not differ significantly between groups. Grade 3 or worse adverse events during the maintenance phase were more common with bevacizumab and capecitabine than with bevacizumab only (45 [49%] of 91 patients vs 25 [27%] of 92 patients). The most common grade 3 or worse events were hand-foot syndrome (28 [31%] in the bevacizumab and capecitabine group vs none in the bevacizumab alone group), hypertension (eight [9%] vs three [3%]), and proteinuria (three [3%] vs four [4%]). Serious adverse events were reported by ten (11%) patients in the bevacizumab and capecitabine group and seven (8%) patients in the bevacizumab only group. INTERPRETATION: Despite prematurely terminated accrual and the lack of information about post-progression treatment, both progression-free survival and overall survival were significantly improved with bevacizumab and capecitabine compared with bevacizumab alone as maintenance treatment. These results might inform future maintenance trials and current first-line treatment strategies for HER2-negative metastatic breast cancer. FUNDING: F Hoffmann-La Roche.

A prognostic factor index for overall survival in patients receiving first-line chemotherapy for HER2-negative advanced breast cancer: an analysis of the ATHENA trial.

BACKGROUND: Evidence-based definitions of 'poor-prognosis' or 'aggressive' advanced breast cancer are lacking. PATIENTS AND METHODS: We developed a prognostic factor index using data from 2203 patients treated with first-line chemotherapy plus bevacizumab for HER2-negative advanced breast cancer. RESULTS: The risk factors most closely associated with worse OS were: disease-free interval ≤24 months; liver metastases or ≥3 involved organ sites; prior anthracycline and/or taxane therapy; triple-negative breast cancer (TNBC); and performance status 2 or prior analgesic/corticosteroid treatment. Risk of death was increased threefold in patients with ≥3 versus ≤1 risk factors (hazard ratio 3.0 [95% CI 2.6-3.4; p < 0.001]; median 16.0 vs 38.8 months, respectively). CONCLUSIONS: This prognostic index may enable identification of patients with a poorer prognosis in whom more intensive systemic regimens may be appropriate. The index may also be considered in designing new trials, although it requires validation in other datasets before extrapolation to non-bevacizumab-containing therapy. ClinicalTrials.gov identifier: NCT00448591.

Rapid and sustained clearance of circulating lymphoma cells after chemotherapy plus rituximab: clinical significance of quantitative t(14;18) PCR monitoring in advanced stage follicular lymphoma patients.

This study of first-line treatment in advanced-stage follicular lymphoma patients analysed the effects of MCP (mitoxantrone, chlorambucil and prednisolone) chemotherapy alone or in combination with rituximab (R-MCP) on circulating lymphoma cells (CLC) and assessed the prognostic value of a quantitative monitoring of CLC. CLC numbers were determined by quantitative polymerase chain reaction (PCR) for the t(14;18)-translocation or by allele-specific PCR for rearranged immunoglobulin heavy chain genes. We analysed blood samples from 43 patients treated in a randomized trial comparing eight cycles of MCP versus R-MCP. Clearance of CLC at the end of therapy was achieved in 21/25 patients (84%) treated with R-MCP compared with 0/18 after MCP alone (P < 0.0001). A > or = 2 log CLC reduction was associated with a favourable clinical response (P = 0.0004) and prolonged event-free survival (P = 0.02). In R-MCP patients, stable CLC numbers or consistently PCR-negative blood samples were associated with a continuing clinical remission whereas in two patients a relapse was preceded by a > or = 2 log CLC increase. This study demonstrated that R-MCP led to a rapid and sustained eradication of CLC and a > or = 2 log CLC reduction was associated with a superior quality and duration of the clinical response.

Long-term treatment with rituximab is feasible in selected patients with B-CLL: response-adjusted low-dose maintenance treatment with rituximab in patients with relapsed B-CLL, who achieved a partial or minimal response to prior rituximab therapy.

The feasibility and efficacy of flexible, response-adjusted rituximab maintenance therapy in B-cell chronic lymphocytic leukemia (B-CLL) was investigated in 12 patients with an at least minor response to four weekly cycles of 375 mg/m(2) of rituximab induction therapy. Rituximab maintenance therapy consisted of infusions of 100 mg rituximab every 4 weeks. If disease progression occurred, either the rituximab dose was increased or the time between infusions was shortened. Treatment-related side effects led to discontinuation of rituximab maintenance therapy in three cases. Maintenance therapy was successfully conducted for > or =6 months in seven cases; three of these individuals have been on maintenance therapy for >1 year to 3.5 years so far. Long-term toxicity, as determined based on hematological and immunological parameters, was mild.

Rituximab added to first-line mitoxantrone, chlorambucil, and prednisolone chemotherapy followed by interferon maintenance prolongs survival in patients with advanced follicular lymphoma: an East German Study Group Hematology and Oncology Study.

PURPOSE: Rituximab has been shown to be active in follicular lymphoma (FL), both as monotherapy and in combination with chemotherapy. We conducted a randomized trial comparing mitoxantrone, chlorambucil, and prednisolone (MCP) chemotherapy plus rituximab with MCP alone. PATIENTS AND METHODS: Previously untreated patients with stage III or IV CD20+ indolent or mantle cell lymphoma were randomly assigned to either eight 28-day cycles of MCP plus rituximab (R-MCP; n = 181) or eight cycles of MCP alone (n = 177). All patients who achieved a complete or partial remission were treated with interferon maintenance until relapse. Herein, we report the results from the primary analysis population of patients with FL, who constituted the majority of patients (56%) recruited to the trial (n = 201; R-MCP, n = 105; MCP, n = 96). RESULTS: Rates of overall and complete response were significantly higher in the R-MCP arm than the MCP arm (overall response, 92% v 75%, respectively; P = .0009; complete response, 50% v 25%, respectively; P = .004). With a median follow-up time of 47 months, median event-free survival (EFS) and progression-free survival (PFS) times were significantly prolonged with R-MCP compared with MCP (EFS, not reached v 26 months, respectively; P < .0001; PFS, not reached v 28.8 months, respectively; P < .0001), and overall survival (OS) was significantly improved with R-MCP compared with MCP (4-year OS rate, 87% v 74%, respectively; P = .0096). CONCLUSION: The R-MCP regimen significantly improves complete and overall response rates, EFS, PFS, and OS in patients with previously untreated advanced FL, without a clinically significant increase in toxicity.

Radioimmunotherapy using 131I-rituximab in patients with advanced stage B-cell non-Hodgkin's lymphoma: initial experience.

PURPOSE: The aim of this study was to evaluate the safety, toxicity and therapeutic response of non-myeloablative radioimmunotherapy using 131I-rituximab in previously heavily treated patients with B-cell non-Hodgkin's lymphoma (B-NHL). METHODS: Nine patients with relapsed, refractory or transformed B-NHL received ten radioimmunotherapies. Patients had a median of 5 (range 2-7) prior standard therapies. Four patients had received prior high-dose chemotherapy followed by autologous stem cell transplantation, and eight had received prior rituximab therapy. Histopathology consisted of four mantle cell, one follicular and four diffuse large B-cell lymphomas. Rituximab, a monoclonal chimeric anti-CD20 antibody (IDEC-C2B8), was labelled with 131I using the Iodogen method. The administered activity (2,200+/-600 MBq) was based on a dosimetrically calculated 45 cGy total-body radiation dose. All patients received an infusion of 2.5 mg/kg of rituximab prior to administration of the radiopharmaceutical. RESULTS: No acute adverse effects were observed after the administration of 131I-rituximab. Radioimmunotherapy was safe in our patient group and achieved one complete response ongoing at 14 months and two partial responses progressing at 12 and 13 months after treatment. One partial responder was re-treated with radioimmunotherapy and achieved an additional progression-free interval of 7 months. Four non-responders with bulky disease died 4.8+/-2.0 months after therapy. Three patients had an elevated serum lactate dehydrogenase (LDH) level prior to radioimmunotherapy and none of the patients responded. Of two patients who received radioimmunotherapy as an additional treatment after salvage chemotherapy, one continues to be disease-free at 9 months and one relapsed at 5 months' follow-up. Reversible grade 3 or 4 haematological toxicity occurred in seven of nine patients. Median nadirs were 35 days for platelets, 44 days for leucocytes and 57 days for erythrocytes. CONCLUSION: Radioimmunotherapy with 131I-rituximab in previously heavily treated B-NHL patients was safe and well tolerated, and four out of ten therapies induced responses. Radioimmunotherapy was less efficient in patients with bulky disease and elevated LDH. Severe haematological toxicity in seven patients did not cause significant clinical problems. Radioimmunotherapy seems to be an additional therapeutic option in carefully selected therapy-refractory B-NHL patients.

Clinical relevance of CD95 (Fas/Apo-1) on T cells of patients with B-cell chronic lymphocytic leukemia.

OBJECTIVE: Apoptosis mediated via CD95 (Fas/Apo-1) is a key regulator for the biology of normal and malignant lymphocytes. Although the function of CD95 on B-cell chronic lymphocytic leukemia cells (B-CLL cells) has been studied intensively, the clinical importance of CD95 expression on normal T cells in B-CLL has not been clarified. This study aimed to investigate whether expression of CD95 on peripheral blood T cells correlates with clinically relevant parameters of B-CLL disease. MATERIALS AND METHODS: Expression of CD95 (Fas/Apo-1) on peripheral blood T lymphocytes of patients with B-CLL was determined using flow cytometry and was correlated with expression of activation markers, sensitivity to apoptosis by anti-CD95, and clinical data, such as blood count, Binet stage, therapy, progression-free probability, and survival probability. RESULTS: Differential CD95 expression did not correlate with activation markers or with levels of apoptosis through anti-CD95. However, high levels of CD95 on T cells from B-CLL patients correlated significantly with low lymphocyte doubling time, increased Binet stages, and requirement for chemotherapeutic treatment. Furthermore, increased cell-surface CD95 on T cells was associated with reduced progression-free probability and poorer survival. CONCLUSIONS: CD95 levels on T cells correlate with the clinical course of B-CLL. Prospective studies appear warranted to investigate whether CD95 on T cells has a direct influence on B-CLL disease progression.

Impact of cardiac surgery using cardiopulmonary bypass on course of chronic lymphatic leukemia: a case-control study.

BACKGROUND: Chronic lymphatic leukemia (CLL) is a common disease among elderly individuals. The number of older patients undergoing operations with cardiopulmonary bypass (CPB) is increasing. The aim of the present study was to evaluate the impact of cardiac surgery using CPB on the long-term course of CLL. METHODS: From 1992 to 2000, a total of 28 patients with CLL underwent heart surgery using CPB at our institution (group I). These patients were compared with 25 patients from the CLL register who were retrospectively matched with regard to preoperative administration of chemotherapy, Binet classification, age, and sex (group II). A time-point was selected for each patient in group II so that the variables for the two groups corresponded in relation to the time of operation of the patients in group I. Midterm follow-up data in both groups were analyzed. RESULTS: There were no differences between groups regarding matched variables. The mean follow-up time was similar in both groups (2.6 +/- 2.2 vs 2.3 +/- 1.3 years, p > 0.5). The 30-day mortality in group I was 14.3%. The mean stay in the intensive care unit was 4.2 +/- 7.5 days; the median number of units of packed red blood cells transfused was three (range 0 to 17). Compared with group II, in group I significantly fewer patients (11 vs 17, p = 0.049) required chemotherapy significantly later (1.98 +/- 2.06 vs 0.84 +/- 1.18 years, p = 0.018). During follow-up, no difference was found between groups regarding severe infections (10 vs 14, p = 0.14). Despite postoperative mortality in group I, the long-term mortality was similar in both groups (p = 0.3). CONCLUSIONS: Cardiac surgery using CPB did not have a negative impact on the natural course of CLL. Moreover, this procedure seems to be associated with a decrease in the number of postoperative chemotherapy administrations and with an increase of chemotherapy-free survival time. Although CLL may be a risk factor in the early postoperative period, it is not a contraindication for cardiac surgery using CPB.