Purpose:

Cyclin D/CDK4/6 is critical in controlling the G1 to S checkpoint. CCND, the gene encoding cyclin D, is known to be amplified in a variety of solid tumors. Palbociclib is an oral CDK4/6 inhibitor, approved in advanced breast cancer in combination with endocrine therapy. We explored the efficacy of palbociclib in patients with nonbreast solid tumors containing an amplification in CCND1, 2, or 3.

Patients and Methods:

Patients with tumors containing a CCND1, 2, or 3 amplification and expression of the retinoblastoma protein were assigned to subprotocol Z1B and received palbociclib 125 mg once daily for 21 days of a 28-day cycle. Tumor response was assessed every two cycles.

Results:

Forty patients were assigned to subprotocol Z1B; 4 patients had outside assays identifying the CCND1, 2, or 3 amplification and were not confirmed centrally; 3 were ineligible and 2 were not treated (1 untreated patient was also ineligible), leaving 32 evaluable patients for this analysis. There were no partial responses; 12 patients (37.5%) had stable disease as best response. There were seven deaths on study, all during cycle 1 and attributable to disease progression. Median progression-free survival was 1.8 months. The most common toxicities were leukopenia (n = 21, 55%) and neutropenia (n = 19, 50%); neutropenia was the most common grade 3/4 event (n = 12, 32%).

Conclusions:

Palbociclib was not effective at treating nonbreast solid tumors with a CCND1, 2, or 3 amplification in this cohort. These data do not support further investigation of single-agent palbociclib in tumors with CCND1, 2, or 3 amplification.

Translational Relevance

CCND1/2/3 amplifications are found in solid tumors and are assessable on commercially available genomic sequencing panels. CCND encodes the cyclin D protein, which complexes with CDK4/6 to allow progression from G1 to S phase of the cell cycle. Thus, tumors that have amplification of CCND1, 2, or 3 may exhibit enhanced proliferation, and be particularly sensitive to palbociclib, a first-in-class oral CDK4/6 inhibitor approved to treat advanced breast cancer. We tested this hypothesis in a subprotocol of the NCI-MATCH trial. Our results do not support the use of palbociclib in nonbreast tumors containing a CCND1, 2, or 3 amplification.

One of the hallmarks of cancer is dysregulation of the cell cycle (1). Although the cell cycle is controlled by multiple pathways and proteins, the key regulator of the G1 to S checkpoint is the retinoblastoma protein (Rb). Unphosphorylated active Rb inhibits the transition to S phase of the cell cycle by coupling to E2F transcription factors and blocking E2F-mediated gene transcription. Expression of cyclin D is highly regulated. Cyclin D complexes with and activates CDK 4 and 6 (CDK 4/6). This cyclin D/CDK4/6 complex phosphorylates and inactivates Rb, releasing E2Fs, and allowing progression into S phase. The key role of cyclin D/CDK4/6 is emphasized in that these complexes are also regulated by upstream mitogenic signaling pathways such as PI3K/AKT, Wnt, ER/PR, and MAPK (2–5). CCND1, 2, and 3 are the genes that encode the Cyclin D protein isoforms.

There are three CDK4/6 inhibitors (palbociclib, ribociclib, and abemaciclib) that are FDA-approved to treat estrogen receptor positive metastatic breast cancer in combination with endocrine therapy. Palbociclib received accelerated approval in combination with the aromatase inhibitor letrozole based upon a near doubling of progression-free survival (PFS) when compared with single-agent letrozole in the first-line metastatic setting, regardless of tumor CCND 1, 2, or 3 amplification (6, 7). Results were confirmed in a randomized double-blinded placebo-controlled phase III trial (8). Although the CDK4/6 inhibitors have been extensively studied in breast cancer, their efficacy shows some promise in other tumor types, though is less well explored. Palbociclib has been reported to stabilize Rb expressing growing teratoma in a group of 12 adults (9) as well as in a case report of a child with central nervous system growing teratoma syndrome who at the time of the report was receiving cycle 22 of therapy (10). Further, in a cohort of 17 heavily pretreated patients with mantle cell lymphoma, which due to the t(11:14) chromosomal translocation, express high levels of CCND1 mRNA, treatment with palbociclib produced a modest objective response in 3 patients (11). Consistent across all of these trials, palbociclib has a favorable side-effect profile, with neutropenia being the most common toxicity. The Cancer Genome Atlas reported that CCND1, 2, or 3 amplification occur at variable rates across many tumor types. We hypothesized that palbociclib would be effective in nonbreast cancers that harbor amplification in the CCND1, 2, or 3 genes.

NCI-MATCH (EAY131, NCT02465060) is a national platform clinical trial designed to assess efficacy of targeted therapies in tumors with specific molecular alterations. The trial is run by the Eastern Cooperative Oncology Group (ECOG)-American College of Radiology Imaging Network (ACRIN) Cancer Research Group through the National Clinical Trials Network and the NCI Community Oncology Research Program. Here, we report the results of the NCI-MATCH Subprotocol Z1B, a phase II single arm study evaluating palbociclib in patients with nonbreast cancers containing a CCND1, 2, or 3 amplification and expression of Rb.

Clinical trial design

The Molecular Analysis for Therapy Choice (NCI-MATCH) trial, developed by ECOG-ACRIN Cancer Research Group (ECOG-ACRIN) and the NCI, aimed to find signals of efficacy for treatments targeted to actionable molecular alterations found in any tumor type. Each drug under investigation in the NCI-MATCH trial is vetted and must have at least preclinical evidence of target engagement (12). Each subprotocol was approved by the Central IRB for the NCI (the NCI Adult IRB). Patients undergo initial eligibility screening and metastatic tumor biopsy in Step 0, where targetable molecular alterations are identified. In Step 1, patients are assigned to subprotocols defined by the molecular alteration, which assessed the efficacy of a specific scientifically rational targeted therapy (or therapies). Patients undergo additional eligibility screening during Step 1 for each subprotocol. Subprotocol Z1B was designed to examine the clinical activity of palbociclib, a CDK4/6 inhibitor, in tumors with CCND1, 2, or 3 amplifications. By inhibiting CDK4/6, palbociclib was hypothesized to mitigate the increase in proliferation due to excess activated Cyclin D/CDK4/6, resulting from amplification of the CCND1, 2, or 3 genes. Because Cyclin D/CDK4/6 signaling is mediated through Rb and preclinical studies show lack of efficacy of CDK4/6i in Rb null tumor cells (13), tumor Rb expression was also required for eligibility on subprotocol Z1B. Written informed consent was obtained by all patients prior to any study activities; the study was conducted in accordance with the Declaration of Helsinki, Belmont Report, and U.S. Common Rule.

Patient selection

Adult patients with any nonbreast solid tumor, lymphoma or myeloma who progressed on standard treatment, or for whom no standard treatment was available, were eligible. Adequate hematopoietic, liver and kidney function, a performance status of ECOG ≤1 were required. Initially submission of fresh tissue was required, but an amendment on May 11, 2017, allowed patients to be enrolled using results from the designated lab network (instead of central testing). To be eligible for this subprotocol, tumors had to contain both an amplification in CCND1, 2, or 3 and Rb expression. CCND amplification was defined as seven or more copies of the gene; Rb expression was defined as 1+ or greater staining by IHC.

Tumor profiling

Actionable mutations were assessed using an NGS panel of 143 genes, including SNVs, indels, amplifications and selected fusions, and IHC assays for PTEN, MLH1, and MSH2 (14, 15). If patients were identified as having a tumor with CCND1, 2, or 3 amplification, reflex testing for Rb expression by IHC was performed to confirm eligibility.

After completion of central testing of 5,954 patients’ fresh tumor biopsies, trial accrual continued by identification of patients whose tumors were found to have eligible alterations by molecular profiling performed for clinical reasons at one of 25 CLIA accredited laboratories approved to screen for NCI-MATCH. Confirmatory central testing was required in order for these patients to be included in the primary analysis.

Assignment to treatment

Patients were assigned using a prospectively defined NCI designed informatics rules algorithm (MATCHBOX), as described previously (12).

Treatment

Patients assigned to subprotocol Z1B received palbociclib 125 mg by mouth once daily for 21 days followed by 7 days off, in 28-day cycles. A complete blood count was performed on day 1 of each cycle, as well as C1D15 and C2D15, or more frequently, as clinically required.

Evaluation of response

Response was evaluated every two cycles using criteria for solid tumors, lymphoma, glioblastoma multiforme, or multiple myeloma according to RECIST v1.1 (16–19).

Toxicity evaluation

Toxicity was evaluated using CTCAEv4. Dose modifications were according to the package insert for palbociclib.

Statistical considerations

The primary objective was to evaluate overall response rate (ORR) to palbociclib. A response rate of 5 of 31 patients (16%) or more was considered a signal of activity. This criterion allowed for 92% power to distinguish a 25% ORR from a null rate of 5%. The one-sided type I error rate was 1.8%. Secondary objectives were PFS at 6 months (PFS6), PFS, toxicity assessment, and evaluation of predictive biomarkers (comutations or other factors that potentially predict which patients will respond). The original accrual goal was 35 patients, to obtain 31 eligible patients. However, this subprotocol could accrue up to 70 patients (35 additional patients), after CTEP review of analysis from the first 31 and would take into account disease histology. Accrual beyond the first 35 would only be allowed for cancer types with less than 10 patients enrolled.

Descriptive statistics were used to summarize patient characteristics, treatment, and study outcomes. A one-sided P value for the ORR was calculated using a one-sample binomial test against the null rate of 5%, and P < 0.05 for the first 31 eligible patients was deemed as statistically significant; if expansion to 70 was permitted, the ORR to be tested was one-sample binomial test against null rate of 5% with P < 0.018 All statistical analyses were performed with R, version 3.5.0 (R Foundation for Statistical Computing).

Data availability

The data underlying this article will be made available for request from the NCTN/NCORP Data Archive (https://nctn-data-archive.nci.nih.gov/) upon completing a Data Request Form for data from NCT04439201.

From August 16, 2016, to December 5, 2017, 40 patients were identified as having CCND1 (39 patients), CCND2 (0 patients), or CCND3 (1 patient) amplification in Step 0. Three patients did not meet eligibility criteria, and 1 patient died prior to starting study therapy. Of the remaining 36 patients, 4 had CCND1 amplification by local testing only; because these were not centrally confirmed, they are excluded from the primary analysis. This left 32 evaluable patients who went on to Step 1 therapy with palbociclib. Patient characteristics are summarized in Table 1. The median age of the patients was 62, IQR 59–67 years. The majority (56%) of patients were male. See Supplementary Table S1 for a summary of the representativeness of our study population. Seventy percent of patients had received three or more prior lines of therapy (mostly chemotherapy) for their malignancies. A wide variety of malignancies was represented in this cohort (shown in Table 2). The majority of patients had adenocarcinoma (n = 15) or squamous (n = 14) histology. The four most commonly represented malignancies were squamous cell lung cancer (n = 5, 13.9%), adenocarcinoma of the prostate (n = 4, 11.1%), squamous cell carcinoma of the head and neck (n = 3, 8.3%), and adenocarcinoma of the colon (n = 3, 8.3%). The most common reason for discontinuation of study therapy was disease progression which occurred in 23 subjects (64%); one subject progressed during C1 and 14 progressed at the first disease assessment timepoint at the end of C2. There were seven deaths due to progression on study, all during cycle 1 of therapy.

Table 1.

Patient characteristics.

Total
Enrolled 
 Ineligible 
 Never started 2a 
 Treated 36 
 Unconfirmed CCND amplification status 
 Final cohort 32 
(Total) 
Female n (%) 14 (44%) 
Age (Y): median (range) 62 (38-78) 
Race: White 28 (88%) 
 Black 1 (3%) 
 Hawaiian/Pacific Island 1 (3%) 
 Not reported 2 (6%) 
Ethnicity: Hispanic 1 (3%) 
ECOG PS 0 8 (25%) 
N prior therapies: 1 3 (9%) 
 2 8 (25%) 
 3 10 (31%) 
 4 11 (34%) 
Wt loss prev 6 mos: 
 <5% 23 (72%) 
 5 to <10% 4 (12%) 
 10 to <20% 4 (11%) 
 ≥20% 1 (3%) 
Amplificationb
CCND1 39 (97.5%) 
CCND2 0 (0%) 
CCND3 1 (2.5%) 
Total
Enrolled 
 Ineligible 
 Never started 2a 
 Treated 36 
 Unconfirmed CCND amplification status 
 Final cohort 32 
(Total) 
Female n (%) 14 (44%) 
Age (Y): median (range) 62 (38-78) 
Race: White 28 (88%) 
 Black 1 (3%) 
 Hawaiian/Pacific Island 1 (3%) 
 Not reported 2 (6%) 
Ethnicity: Hispanic 1 (3%) 
ECOG PS 0 8 (25%) 
N prior therapies: 1 3 (9%) 
 2 8 (25%) 
 3 10 (31%) 
 4 11 (34%) 
Wt loss prev 6 mos: 
 <5% 23 (72%) 
 5 to <10% 4 (12%) 
 10 to <20% 4 (11%) 
 ≥20% 1 (3%) 
Amplificationb
CCND1 39 (97.5%) 
CCND2 0 (0%) 
CCND3 1 (2.5%) 

Abbreviations: mos, months; prev, previous; PS, performance status; Tx, treatment; Wt, weight; Y, years.

aOne subject also ineligible.

bAmplifications reported in all 40 patients assigned to subprotocol Z1B during Step 1, N = 40; other statistics are based on the 32 eligible and treated patients.

Table 2.

Histologic tumor subtypes among analyzable patients in NCI MATCH subprotocol Z1B.

Total (n = 32)
Adenocarcinoma (n14 (43.8%) 
 Prostate 3 (9.4%) 
 Colona 3 (9.4%) 
 GEJ 2 (6.3%) 
 Stomach 2 (6.3%) 
 Endometrium (endometrioid) 1 (3.1%) 
 Lung 1 (3.1%) 
 Pancreas 1 (3.1%) 
 Rectum 1 (3.1%) 
Squamous cell CA (n13 (40.1%) 
 Lung 5 (15.6%) 
 Oropharynx 3 (9.4%) 
 Glottis or larynx 2 (6.3%) 
 Esophagus 1 (3.1%) 
 Anus 1 (3.1%) 
 Vulva 1 (3.1%) 
Transitional cell bladder (n2 (6.3%) 
Serous CA, fallopian tube 1 (3.1%) 
Adenoid cystic CA parotid 1 (3.1%) 
Adenosquamous CA GEJ 1 (3.1%) 
Neuroendocrine unknown primary 1 (3.1%) 
Sarcomatoid CA 1 (3.1%) 
Total (n = 32)
Adenocarcinoma (n14 (43.8%) 
 Prostate 3 (9.4%) 
 Colona 3 (9.4%) 
 GEJ 2 (6.3%) 
 Stomach 2 (6.3%) 
 Endometrium (endometrioid) 1 (3.1%) 
 Lung 1 (3.1%) 
 Pancreas 1 (3.1%) 
 Rectum 1 (3.1%) 
Squamous cell CA (n13 (40.1%) 
 Lung 5 (15.6%) 
 Oropharynx 3 (9.4%) 
 Glottis or larynx 2 (6.3%) 
 Esophagus 1 (3.1%) 
 Anus 1 (3.1%) 
 Vulva 1 (3.1%) 
Transitional cell bladder (n2 (6.3%) 
Serous CA, fallopian tube 1 (3.1%) 
Adenoid cystic CA parotid 1 (3.1%) 
Adenosquamous CA GEJ 1 (3.1%) 
Neuroendocrine unknown primary 1 (3.1%) 
Sarcomatoid CA 1 (3.1%) 

Abbreviations: CA, cancer; GEJ, gastroesophageal junction.

aTwo cases of mucinous colon CA.

There were no partial or complete responses. The best RECIST response observed was stable disease (SD) occurring in 12 patients (Table 3). Of the 32 patients in the final cohort, 8 patients were not evaluable for response due to death during cycle 1 (n = 7) or rapid clinical disease progression during cycle 1 (n = 1), thus not having anatomic imaging with which to calculate a RECIST response. A waterfall plot depicting the percent change in tumor volume per RECIST v1.1 in each evaluable patient is shown in Fig. 1A. The largest reduction in tumor volume was 13% and was observed in a patient with adenocarcinoma of the pancreas. To further examine those patients with SD, Fig. 1B highlights the time on treatment with palbociclib. Most patients with SD experienced progression of disease by cycle 4 of therapy. Four patients remained on study for 4 cycles or longer: individual patients with squamous cell lung cancer, squamous cell carcinoma of the head neck larynx, adenoid cystic carcinoma of the parotid, and adenocarcinoma of the pancreas, were treated on study for 11, 8, 8, and 5 cycles, respectively. The range of prior lines of therapy in these four subjects was one to two, as compared with the eight subjects who came off trial in cycle 1 whose number of prior lines ranged from two to nine. The median PFS among patients treated with palbociclib was 1.8 months and the estimated 6-month PFS was 13% (90% CI, 5%–29%; Fig. 2A). The median overall survival was 7.7 months (Fig. 2B).

Table 3.

Best confirmed response.

N
PR 
SD 12 
PD 12 
NE 
Total 32 
N
PR 
SD 12 
PD 12 
NE 
Total 32 

Abbreviations: NE, not evaluable; PD, progressive disease; PR, partial response.

Figure 1.

Best response to palbociclib in patients with tumors containing a CCND1, 2, or 3 amplification. A, Waterfall plot of best change from baseline for n = 22 patients with follow-up target lesion measurements. Color shows histology. For the remaining n = 10 patients: unevaluable (n = 8), PD due to new lesion (n = 2). B, Treatment duration for n = 12 patients who achieved SD. Abbreviations: PD, progressive disease; SCC, squamous cell carcinoma; AdenoCA, adenocarcinoma; GEJ, gastroesophageal junction; CA, carcinoma.

Figure 1.

Best response to palbociclib in patients with tumors containing a CCND1, 2, or 3 amplification. A, Waterfall plot of best change from baseline for n = 22 patients with follow-up target lesion measurements. Color shows histology. For the remaining n = 10 patients: unevaluable (n = 8), PD due to new lesion (n = 2). B, Treatment duration for n = 12 patients who achieved SD. Abbreviations: PD, progressive disease; SCC, squamous cell carcinoma; AdenoCA, adenocarcinoma; GEJ, gastroesophageal junction; CA, carcinoma.

Close modal
Figure 2.

A, PFS among patients with CCND1, 2, or 3 amplification receiving palbociclib on NCI-MATCH subprotocol Z1B. B, Overall survival among patients with CCND1, 2, or 3 amplification receiving palbociclib on NCI-MATCH subprotocol Z1B.

Figure 2.

A, PFS among patients with CCND1, 2, or 3 amplification receiving palbociclib on NCI-MATCH subprotocol Z1B. B, Overall survival among patients with CCND1, 2, or 3 amplification receiving palbociclib on NCI-MATCH subprotocol Z1B.

Close modal

Adverse events (AE) assessed as possibly, probably, or definitely related to palbociclib are summarized in Table 4. The most commonly reported treatment related AEs were due to myelosuppression: leukopenia (n = 21, 58.3%), neutropenia (n = 19, 52.8%), thrombocytopenia (n = 14, 38.9%), and anemia (n = 13, 36%). There were 19 grade 3/4 events, most of which were neutropenia (12/19, 63.2%). Other Grade 3/4 events that occurred in more than 1 patient were leukopenia (7, 36.8%), thrombocytopenia (4, 21%), anemia (2, 10.5%), and fatigue (2, 10.5%). There were only two grade 4 events (neutropenia and thrombocytopenia). Common nonhematologic toxicities included fatigue (10, 27.8%), nausea (8, 22.2%), elevation in aspartate aminotransferase (5, 13.9%), and elevation in alanine aminotransferase (4, 11.1%).

Table 4.

Adverse events occurring in ≥ 10% of patients that possibly, probably, or definitely were related to palbociclib.

Toxicity grade (n = 38)
Toxicity type1, 234
Alanine aminotransferase increased — 
Anemia 11 — 
Anorexia — — 
Aspartate aminotransferase increased — 
Constipation — — 
Fatigue — 
Lymphocyte count decreased — 
Mucositis oral — — 
Nausea — 
Neutrophil count decreased 11 
Platelet count decreased 10 
White blood cells decreased 14 — 
Toxicity grade (n = 38)
Toxicity type1, 234
Alanine aminotransferase increased — 
Anemia 11 — 
Anorexia — — 
Aspartate aminotransferase increased — 
Constipation — — 
Fatigue — 
Lymphocyte count decreased — 
Mucositis oral — — 
Nausea — 
Neutrophil count decreased 11 
Platelet count decreased 10 
White blood cells decreased 14 — 

Molecular alterations co-occurring with CCND1 or CCND3 amplifications were common across the study population and were found in all but 2 patients enrolled on the Z1B subprotocol. The most commonly co-occurring alteration was TP53 mutation that was found in 21 subjects. The second most common co-alterations were mutations in KRAS and MYC, which were found in four subjects each. Five subjects had only CCND1 amplification on NGS analysis. There were no co-alterations that occurred more commonly among the 4 patients who had SD for 4 cycles or longer. Of note, CCNE amplification was NOT observed in any of these tumors. Finally, degree of CCND amplification was not associated with SD (P = 0.5 comparing mean degree of amplification among patients with SD compared with those with PD).

Subprotocol Z1B of the NCI-MATCH trial examined the efficacy of palbociclib in patients with solid tumors (other than breast cancer) containing amplifications in CCND1, 2, or 3 with concomitant expression of the Rb protein. Of the 32 evaluable patients, 31 had a tumor with CCND1 amplification and 1 had CCND3 amplification. There were no objective responses observed in this NCI-MATCH subprotocol. Four patients had SD for at least six cycles, and no patient stayed on palbociclib longer than 10 cycles. The AE profile observed in this subprotocol was similar to those reported in the previously published trials of palbociclib in patients with breast cancer (7, 8, 20, 21): neutropenia was the most common AE and was also the most common grade 3/4 event, though febrile neutropenia was not observed.

Examination of genomic biomarkers assessed at the time of study enrollment failed to identify any additional genomic alterations that were unique to the tumors of the four individuals who derived potential clinical benefit. Although these results support the safety of palbociclib in the treatment of advanced solid tumors, they do not support its use in nonbreast cancers containing CCND1 or 3 amplifications with Rb expression. These findings are consistent with recently published studies in metastatic breast cancer, which concluded that CCND1 amplification did not predict response to palbociclib and letrozole. PALOMA1 (7), a phase I/II unblinded trial that randomized patients with breast cancer to receive letrozole alone or in combination with palbociclib in the first-line metastatic setting, was enriched for patients with tumors containing either CCND1 amplification or loss of p16. In this study, the PFS of patients treated with palbociclib/letrozole was significantly better than that in patients treated with letrozole alone. However, CCND1 amplification was not associated with superior clinical benefit from letrozole/palbociclib (6). CCND1 amplification also failed to predict response to single-agent palbociclib in a smaller study in patients with metastatic breast cancer (21). There have been no predictive biomarkers discovered for palbociclib, although there are biomarkers that may predict lack of response: loss of Rb and high CCNE mRNA expression (22).

Our study is limited most significantly by the number of early events. Of the 40 patients who were enrolled into this subprotocol from Step 0, 1 patient died before reaching Step 1, 7 patients died during C1, 1 patient progressed during C1, and 14 additional patients progressed by C3. Thus, over half of patients either died or progressed within 2 months of identification of the CCND amplification. The eight early deaths were not due to prolonged time between Step 0 and Step 1 [median days 41 for the 8 patients who experienced early death compared with 42 for the remainder of the cohort (P > 0.9)]. This high rate of early events may be a result of the heavily pretreated nature of the study population and may reflect disease states too advanced to respond to a cytostatic drug. Although in the total study population, the median number of lines of therapy was 3 (1 to 10), the 8 patients who passed away had numerically more prior lines of therapy (median lines 3, range 2–10). Thus, rather than a biomarker of response to palbociclib, it may be a passenger mutation acquired over time during the course of multiple therapies and a biomarker of poor outcome. The idea of CCND1 amplification being a biomarker of poor outcome is also supported by a study performed by Chen and colleagues that examined over 25,000 solid tumors. This study found that presence of CCND1 amplification correlated with worse overall survival and worse response to immune checkpoint inhibitors (23). Whether palbociclib might be effective as earlier-line metastatic treatment remains an open question.

Another limitation to the current analysis is the lack of pathway functional analysis. Further studies will be undertaken to more thoroughly examine the tumor genomes in patients enrolled onto this subprotocol to try to elucidate why some tumors progressed so quickly whereas others remained stable. It is plausible that there is an intricate interplay between CCND and its regulators, such as AMBRA1 (24–26), that may impact response to palbociclib.

In conclusion, this study is the first to examine the efficacy of palbociclib in CCND1, 2, or 3 amplified nonbreast solid tumors. Although our study confirms safety of the drug, our results do not support its use as a single agent in patients with solid tumors that contain amplification of the CCND1 or 3 genes. Thus, future trials should concentrate on rational palbociclib drug combinations and use more in-depth functional assays of enzyme and pathway function to fully understand what molecular alterations are predictive biomarkers for this drug. Additional analyses are currently ongoing and may shed light on what drugs or drug combinations (with or without palbociclib) will be effective in patients with CCND amplified solid tumors.

The Editor-in-Chief of Clinical Cancer Research is an author on this article. In keeping with AACR editorial policy, a senior member of the Clinical Cancer Research editorial team managed the consideration process for this submission and independently rendered the final decision concerning acceptability.

A.S. Clark reports grants from Novartis and Lilly outside the submitted work. R.S. Finn reports grants and personal fees from Pfizer during the conduct of the study as well as personal fees from AstraZeneca, Cstone, Exelixis, and Hengrui and grants and personal fees from Bayer, BMS, Eisai, Merck, Eli Lilly, and Adaptimmune outside the submitted work. A.M. DeMichele reports grants from Pfizer, Novartis, and Genentech outside the submitted work; in addition, A.M. DeMichele's spouse is on a Pfizer data and safety monitoring board for a GI drug (non-oncology). E.P. Mitchell receives institutional research funding from Genentech and Sanofi; has served as a consultant or advisor to BMS, Genentech, Merck, and Novartis; has received honoraria from Exelixis and Sanofi; serves on the speakers bureau of Ipsen; and has a leadership role in Corvus Pharmaceuticals. F.I. Arnaldez reports other support from AstraZeneca, PLC outside the submitted work. R.J. Gray reports grants from NCI during the conduct of the study. V. Wang reports grants from NIH/NCI during the conduct of the study. S.R. Hamilton reports other support from ECOG-ACRIN during the conduct of the study. C.L. Artega reports grants from Pfizer, Lilly, and Takeda and personal fees from Novartis, Lilly, Taiho Oncology, Daiichi Sankyo, AstraZeneca, Sanofi, Merck, OrigiMed, Immunomedics, Susan G. Komen Foundation, and Arvinas outside the submitted work; in addition, C.L. Arteaga has a patent for Provista with royalties paid. P.J. O'Dwyer reports grants from Pfizer during the conduct of the study. K.T. Flaherty reports personal fees from Clovis Oncology, Strata Oncology, Checkmate Pharmaceuticals, Kinnate Biopharma, Scorpion Therapeutics, PIC Therapeutics, Apricity, Oncoceutics, Fog Pharma, Tvardi, xCures, Monopteros, Vibliome, ALX Oncology, OMRx, Soley Therapeutics, Quanta Therapeutics, Lilly, Genentech, and Takeda; grants and personal fees from Novartis; and grants from Sanofi during the conduct of the study. No disclosures were reported by the other authors.

A.S. Clark: Conceptualization, data curation, formal analysis, investigation, visualization, methodology, writing–original draft, writing–review and editing. F. Hong: Data curation, formal analysis, visualization, writing–original draft, writing–review and editing. R.S. Finn: Conceptualization, writing–review and editing. A.M. DeMichele: Conceptualization, supervision, investigation, writing–original draft, writing–review and editing. E.P. Mitchell: Supervision, investigation, methodology, writing–review and editing. J. Zwiebel: Supervision, writing–review and editing. F.I. Arnaldez: Supervision, writing–review and editing. R.J. Gray: Conceptualization, resources, supervision, methodology, writing–review and editing. V. Wang: Conceptualization, resources, supervision, methodology, writing–review and editing. L.M. McShane: Conceptualization, resources, supervision, methodology, writing–review and editing. L.V. Rubinstein: Conceptualization, supervision, methodology, writing–review and editing. D. Patton: Resources, supervision, methodology, writing–review and editing. P.M. Williams: Conceptualization, resources, supervision, writing–review and editing. S.R. Hamilton: Conceptualization, resources, supervision, methodology, writing–review and editing. M.S. Copur: Conceptualization, supervision, writing–review and editing. S.S. Kasbari: Conceptualization, supervision, writing–review and editing. R. Thind: Conceptualization, supervision, writing–review and editing. B.A. Conley: Conceptualization, supervision, methodology, writing–review and editing. C.L. Arteaga: Conceptualization, supervision, methodology, writing–review and editing. P.J. O'Dwyer: Conceptualization, supervision, investigation, writing–review and editing. L.N. Harris: Conceptualization, supervision, methodology, writing–review and editing. A.P. Chen: Conceptualization, supervision, methodology, writing–review and editing. K.T. Flaherty: Conceptualization, resources, supervision, investigation, writing–review and editing.

This study was coordinated by the ECOG-ACRIN Cancer Research Group (Peter J. O'Dwyer, MD, and Mitchell D. Schnall, MD, PhD, Group Co-Chairs) and supported by the NCI of the NIH under the following award numbers: U10CA180820, U10CA180794, UG1CA233341, UG1CA189809, U10CA180888, UG1CA189858, UG1CA233302, and UG1CA233180. Palbociclib was provided by Pfizer for this study. The content is solely the responsibility of the authors and does not necessarily represent the official views of the NIH. Mention of trade names, commercial products, or organizations does not imply endorsement by the U.S. government.

The publication costs of this article were defrayed in part by the payment of publication fees. Therefore, and solely to indicate this fact, this article is hereby marked “advertisement” in accordance with 18 USC section 1734.

Note: Supplementary data for this article are available at Clinical Cancer Research Online (http://clincancerres.aacrjournals.org/).

1.
Hanahan
D
,
Weinberg
RA
.
Hallmarks of cancer: the next generation
.
Cell
2011
;
144
:
646
74
.
2.
Lange
CA
,
Yee
D
.
Killing the second messenger: targeting loss of cell cycle control in endocrine-resistant breast cancer
.
Endocr Relat Cancer
2011
;
18
:
C19
24
.
3.
Caldon
CE
,
Daly
RJ
,
Sutherland
RL
,
Musgrove
EA
.
Cell cycle control in breast cancer cells
.
J Cell Biochem
2006
;
97
:
261
74
.
4.
Buckley
MF
,
Sweeney
KJ
,
Hamilton
JA
,
Sini
RL
,
Manning
DL
,
Nicholson
RI
, et al
.
Expression and amplification of cyclin genes in human breast cancer
.
Oncogene
1993
;
8
:
2127
33
.
5.
Dickson
C
,
Fantl
V
,
Gillett
C
,
Brookes
S
,
Bartek
J
,
Smith
R
, et al
.
Amplification of chromosome band 11q13 and a role for cyclin D1 in human breast cancer
.
Cancer Lett
1995
;
90
:
43
50
.
6.
Finn
RS
,
Crown
JP
,
Lang
I
,
Boer
K
,
Bondarenko
IM
,
Kulyk
SO
, et al
.
Final results of a randomized Phase II study of PD 0332991, a cyclin-dependent kinase (CDK)-4/6 inhibitor, in combination with letrozole vs letrozole alone for first-line treatment of ER+/HER2-advanced breast cancer (PALOMA-1; TRIO-18)
.
Cancer Res
2014
;
74
(
19_suppl
):
CT101
.
7.
Finn
RS
,
Crown
JP
,
Lang
I
,
Boer
K
,
Bondarenko
IM
,
Kulyk
SO
, et al
.
The cyclin-dependent kinase 4/6 inhibitor palbociclib in combination with letrozole versus letrozole alone as first-line treatment of oestrogen receptor-positive, HER2-negative, advanced breast cancer (PALOMA-1/TRIO-18): a randomised phase 2 study
.
Lancet Oncology
2015
;
16
:
25
35
.
8.
Finn
RS
,
Martin
M
,
Rugo
HS
,
Jones
S
,
Im
S-A
,
Gelmon
K
, et al
.
Palbociclib and Letrozole in Advanced Breast Cancer
.
N Engl J Med
2016
;
375
:
1925
36
.
9.
Narayan
V
,
Hwang
W-T
,
Lal
P
,
Rosen
MA
,
Gallagher
M
,
O'Dwyer
PJ
, et al
.
Cyclin-dependent kinase 4/6 inhibition for the treatment of unresectable mature teratoma: long-term follow-up of a Phase II study
.
Clin Genitourin Cancer
2016
;
14
:
504
10
.
10.
Schultz
KAP
,
Petronio
J
,
Bendel
A
,
Patterson
R
,
Vaughn
DJ
.
PD0332991 (palbociclib) for treatment of pediatric intracranial growing teratoma syndrome
.
Pediatr Blood Cancer
2015
;
62
:
1072
4
.
11.
Lee
C
,
Huang
X
,
Di Liberto
M
,
Martin
P
,
Chen-Kiang
S
.
Targeting CDK4/6 in mantle cell lymphoma
.
Ann Lymphoma
2020
;
4
:
1
.
12.
Flaherty
KT
,
Gray
R
,
Chen
A
,
Li
S
,
Patton
D
,
Hamilton
SR
, et al
.
The molecular analysis for therapy choice (NCI-MATCH) trial: lessons for genomic trial design
.
J Natl Cancer Inst
2020
;
112
:
1021
9
.
13.
Shapiro
GI
.
Cyclin-dependent kinase pathways as targets for cancer treatment
.
J Clin Oncol
2006
;
24
:
1770
83
.
14.
Lih
C-J
,
Harrington
RD
,
Sims
DJ
,
Harper
KN
,
Bouk
CH
,
Datta
V
, et al
.
Analytical validation of the next-generation sequencing assay for a nationwide signal-finding clinical trial molecular analysis for therapy choice clinical trial
.
J Mol Diagn
2017
;
19
:
313
27
.
15.
Khoury
JD
,
Wang
W-L
,
Prieto
VG
,
Medeiros
LJ
,
Kalhor
N
,
Hameed
M
, et al
.
Validation of immunohistochemical assays for integral biomarkers in the NCI-MATCH EAY131 clinical trial
.
Clin Cancer Res
2018
;
24
:
521
31
.
16.
Schwartz
LH
,
Seymour
L
,
Litière
S
,
Ford
R
,
Gwyther
S
,
Mandrekar
S
, et al
.
RECIST 1.1-Standardisation and disease-specific adaptations: perspectives from the RECIST working group
.
Eur J Cancer
2016
;
62
:
138
45
.
17.
Cheson
BD
,
Fisher
RI
,
Barrington
SF
,
Cavalli
F
,
Schwartz
LH
,
Zucca
E
, et al
.
Recommendations for initial evaluation, staging, and response assessment of Hodgkin and non-Hodgkin lymphoma: the Lugano classification
.
J Clin Oncol
2014
;
2
:
3059
.
18.
Wen
PY
,
Macdonald
DR
,
Reardon
DA
,
Cloughesy
TF
,
Sorensen
AG
,
Galanis
E
, et al
.
Updated response assessment criteria for high-grade gliomas: response assessment in neuro-oncology working group
.
J Clin Oncol
2010
;
28
:
1963
72
.
19.
Kumar
S
,
Paiva
B
,
Anderson
KC
,
Durie
B
,
Landgren
O
,
Moreau
P
, et al
.
International myeloma working group consensus criteria for response and minimal residual disease assessment in multiple myeloma
.
Lancet Oncology
2016
;
17
:
E328
46
.
20.
Turner
NC
,
Ro
J
,
André
F
,
Loi
S
,
Verma
S
,
Iwata
H
, et al
.
Palbociclib in hormone-receptor-positive advanced breast cancer
.
N Engl J Med
2015
;
373
:
209
19
.
21.
DeMichele
A
,
Clark
AS
,
Tan
KS
,
Heitjan
DF
,
Gramlich
K
,
Gallagher
M
, et al
.
CDK 4/6 inhibitor palbociclib (PD0332991) in Rb+ advanced breast cancer: phase II activity, safety, and predictive biomarker assessment
.
Clin Cancer Res
2015
;
21
:
995
1001
.
22.
Turner
NC
,
Liu
Y
,
Zhu
Z
,
Loi
S
,
Colleoni
M
,
Loibl
S
, et al
.
Cyclin E1 expression and palbociclib efficacy in previously treated hormone receptor-positive metastatic breast cancer
.
J Clin Oncol
2019
;
37
:
1169
78
.
23.
Chen
Y
,
Huang
Y
,
Gao
X
,
Li
Y
,
Lin
J
,
Chen
L
, et al
.
CCND1 amplification contributes to immunosuppression and is associated with a poor prognosis to immune checkpoint inhibitors in solid tumors
.
Front Immunol
2020
;
11
:
1620
.
24.
Maiani
E
,
Milletti
G
,
Nazio
F
,
Holdgaard
SG
,
Bartkova
J
,
Rizza
S
, et al
.
AMBRA1 regulates cyclin D to guard S-phase entry and genomic integrity
.
Nature
2021
;
592
:
799
803
.
25.
Chaikovsky
AC
,
Li
C
,
Jeng
EE
,
Loebell
S
,
Lee
MC
,
Murray
CW
, et al
.
The AMBRA1 E3 ligase adaptor regulates the stability of cyclin D
.
Nature
2021
;
592
:
794
8
.
26.
Simoneschi
D
,
Rona
G
,
Zhou
N
,
Jeong
Y-T
,
Jiang
S
,
Milletti
G
, et al
.
CRL4(AMBRA1) is a master regulator of D-type cyclins
.
Nature
2021
;
592
:
789
93
.
This open access article is distributed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0) license.