Cladribine With Simultaneous or Delayed Rituximab to Treat Hairy Cell Leukemia: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Cladribine With Simultaneous or Delayed Rituximab to Treat Hairy Cell Leukemia (NCT00923013), a randomized phase 2 study. The primary outcome is Response Rate Comparing Minimal Residual Disease (MRD) at 6 Months After Start of Treatment in Comparison Groups.

2. Clinical Question

This is a question about an early laboratory and tissue-based response measure, not a direct comparison of long-term disease control. The registry describes a participant as having minimal residual disease status when all three specified assessments are negative for hairy cells. It also describes participants meeting that definition as without HCL disease at that time point. The outcome is therefore tied to the assessment at 6 months, rather than being a measure of later relapse or survival.

The comparison is randomized, but the registry’s outcome description says the newly diagnosed and once-relapsed groups were split and both groups randomized. It does not explain what distinguishes the two reported subgroups within each randomized arm. That distinction matters when interpreting the four percentages: they are separate posted subgroup results, not one combined percentage for each treatment strategy. The subgroup definitions and the reason for presenting these results separately are not reported in the registry record.

3. Trial Design

The study is listed as a Phase 2 randomized trial with a parallel-group model and no masking. Its title concerns cladribine with simultaneous or delayed rituximab to treat Hairy Cell Leukemia and eliminate minimal residual disease. The listed enrollment is 175. The registry status is active, not recruiting; the posted status does not establish that every participant has completed all follow-up or that the study is complete.

The primary analysis concerns Cohort 1’s randomized groups. One group received cladribine with immediate rituximab. The other received cladribine, with rituximab delayed by at least 6 months if and when minimal residual disease was detected. The registry separately lists a non-randomized group receiving cladribine with immediate rituximab before the first of five daily cladribine doses on day 1. That group is not part of the reported randomized primary comparison. Cohort 2 and Cohort 3 results are also explicitly excluded from the investigator’s primary comparison description.

The primary outcome was assessed by restaging 6 months after treatment began. The registry describes evaluation with bone marrow and blood flow cytometry and histochemistry of the core biopsy. It lists three tests as necessary for the stated minimal-residual-disease status: all must be negative for hairy cells. The reported outcome values are percentages of participants, accompanied by group counts in the outcome record.

Rituximab is also listed as a treatment that may be given after the 6-month point in the delayed group when minimal residual disease is detected. The registry lists minimal-residual-disease-free survival after cladribine and up to two courses of rituximab as a secondary outcome. The detailed analysis plan, the full schedule for that secondary outcome, allocation concealment, and the original sample-size justification are not reported in the registry record. The record does not state whether interim analyses were planned.

4. Participant Flow and Accounting

The registry reports how participants moved through each stage of the study. All counts below are exactly as posted; missing counts are not inferred from other stages.

Overall Study

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: Cohort 2, Arm 3 and Cohort 3, Arm 3 are not reported because the investigator is only comparing the randomized groups. The primary goal is comparing the randomization and Cohort 2 was not randomized.

5. Baseline Characteristics

The table reproduces the baseline characteristics posted in the registry, which describe the participants analysed at baseline and help show whether the randomized groups were comparable.

Only the first 6 of 7 groups are shown.

6. Primary Endpoint

The registry lists the primary outcome as Response Rate Comparing Minimal Residual Disease (MRD) at 6 Months After Start of Treatment in Comparison Groups, measured over Restaged 6 months after the start of treatment.

The primary endpoint is the percentage of participants meeting minimal-residual-disease status at restaging 6 months after the start of treatment. It is described as a response rate comparing minimal residual disease in the randomized groups. The registry’s definition requires negative findings for hairy cells on all three assessments: bone marrow and blood flow cytometry and histochemistry of the core biopsy. A participant meeting that definition is considered to be without HCL disease at that time point.

This endpoint is used to capture disease detectable by the specified tests after initial treatment. It is not the same as a measure of overall survival, duration of remission, or later relapse. The registry’s background explains that minimal residual disease can remain detectable in complete remission after cladribine and describes it as a risk for early relapse. That rationale explains why a laboratory-based disease-status endpoint is relevant to the study question, but it does not establish that a 6-month result predicts an individual participant’s later course.

Because the outcome depends on multiple assessments, a participant’s classification relies on each of them being negative. The registry does not report how missing, indeterminate, or technically inadequate test results were handled. It also does not report a separate endpoint definition for the four subgroup results. Those details would help clarify how the percentage was calculated for participants without a complete set of assessments.

7. Results Posted in the Registry

• Cohort 1 Arm 1 SubGroup 2 -Cladribine + Rituximab: 62.5% (20/32) versus 97.1% (33/34) on control; risk difference -34.6 percentage points (95% CI -52.3 to -16.8), risk ratio 0.64 (0.49–0.85); unadjusted two-proportion z-test p = <0.001.
• Cohort 1 Arm 2 SubGroup 1-Cladribine(+Rituximab After 6 Months if Minimal Residual Disease Detected): 23.5% (8/34) versus 97.1% (33/34) on control; risk difference -73.5 percentage points (95% CI -88.9 to -58.2), risk ratio 0.24 (0.13–0.45); unadjusted two-proportion z-test p = <0.001.
• Cohort 1 Arm 2 SubGroup 2-Cladribine(+Rituximab After 6 Months if Minimal Residual Disease Detected): 3.3% (1/30) versus 97.1% (33/34) on control; risk difference -93.7 percentage points (95% CI -102.3 to -85.2), risk ratio 0.03 (0.00–0.24); unadjusted two-proportion z-test p = <0.001.

8. Statistical Interpretation

9. Statistical Methods Explained

The primary outcome is binary at the participant level: each person either meets the stated minimal-residual-disease status at the 6-month assessment or does not. The registry reports the result as a percentage of participants. In general, a percentage communicates the frequency of the outcome in a group, while the group size indicates how much information contributes to that estimate. The posted results give both for each subgroup.

What does a risk difference describe?

A risk difference compares the outcome proportions in two groups by subtraction. In general, it is expressed on the percentage-point scale and retains the direction of the contrast: a negative estimate means the listed comparison group has a lower outcome proportion than the reference group under the comparison’s sign convention. The posted comparisons use Cohort 1 Arm 1 SubGroup 1 as the reference. The three listed comparison groups each have a negative risk-difference estimate and a reported unadjusted p-value of <0.001.

A risk difference is an absolute contrast, unlike a risk ratio, which compares proportions multiplicatively, or an odds ratio, which compares odds. The record includes risk-ratio and odds-ratio estimates as well as risk differences, but the primary explanatory focus is the absolute scale because it directly describes the difference in outcome frequency. These measures answer related but distinct questions and should not be treated as interchangeable.

How should the p-values be read?

In general, a p-value assesses how compatible the observed data are with a specified null hypothesis, under the test’s assumptions. A value reported as <0.001 indicates that the result would be unusual under the tested null model. It does not measure the size or importance of the contrast, the probability that the null hypothesis is true, or the probability that the finding will recur. The p-values in the record are identified as unadjusted. The multiplicity plan is not reported, so the record does not establish whether these multiple comparisons were accounted for in the analysis plan.

The distinction between statistical evidence and effect magnitude is important. The percentages and risk-difference estimates describe the observed separation; the p-values describe compatibility with the null model. Confidence intervals add information about the range of estimates consistent with the observations under the calculation method. Neither a small p-value nor an interval excluding zero resolves uncertainty about the subgroup definitions, missing results, or relevance to later outcomes.

Why do confidence intervals matter?

In general, a confidence interval reflects both the estimated contrast and its sampling uncertainty. A wider interval signals less precision than a narrower interval, all else equal. In this trial’s posted comparisons, the intervals are reported for each risk difference. They exclude zero, but their width varies. One reported lower bound extends below -1. For a risk difference between proportions, values cannot be below -1 as a possible true difference; such an endpoint can arise from an approximate interval method in small samples. It is a reason to interpret that interval cautiously rather than as a biologically possible effect range.

What does randomization contribute?

In general, random allocation is intended to make treatment groups comparable on average at the point of assignment, including with respect to measured and unmeasured characteristics. The registry identifies the study as randomized, parallel, and unmasked. Randomization supports an intervention comparison, but it does not automatically resolve the interpretation of separate subgroup rows. The registry does not describe the two subgroup definitions or provide baseline details for each of the four reported entries. Nor does the record specify the analysis population or adjustment variables. Those omissions limit assessment of how closely the posted subgroup contrasts correspond to the randomized comparison as a whole.

What cannot be inferred from the posted results?

The outcome is assessed at one stated time point. It does not directly measure time until recurrence or survival. The registry lists a secondary minimal-residual-disease-free survival outcome after cladribine and up to two courses of rituximab, but no analysis entries are posted. The record also does not report a statistical analysis plan, the original sample-size assumptions, a missing-data method, or an interim-analysis plan. These items cannot be reconstructed from the observed percentages or p-values.

Finally, statistical methods rely on assumptions, including how observations are classified and whether the comparison is conducted as intended. The registry’s short endpoint description specifies the tests and timing but does not explain handling of incomplete or indeterminate tests. The posted findings are best read as descriptive subgroup percentages and unadjusted comparisons for the stated endpoint, rather than as a complete account of all planned analyses or a long-term clinical conclusion.

10. Confidence Intervals and Precision

The primary outcome estimates come from groups of 34, 32, 34, and 30 participants. The registry reports 97.1% and 62.5% for the two immediate-treatment subgroup entries, and 23.5% and 3.3% for the two delayed-treatment subgroup entries. The displayed percentages are point estimates: each is the observed proportion for its particular subgroup, not a guarantee of the proportion that would be seen in another set of participants.

The posted confidence intervals accompany each risk-difference comparison with the reference subgroup. In general, a confidence interval communicates the uncertainty associated with an estimate under a statistical method; a narrower interval indicates greater precision than a wider one. All three reported risk-difference intervals exclude zero. Their widths differ, so the amount of uncertainty is not identical across comparisons. The estimates and intervals should be considered together rather than treating the p-values alone as a measure of precision.

One interval has a lower endpoint of -1.023. A risk difference between two proportions is bounded by -1 and 1, so an endpoint beyond that range is not a possible value of the underlying difference. It reflects the behavior of the interval calculation rather than a plausible effect beyond the bounds of a proportion difference. This cautions against reading that interval literally at its extreme.

Precision is also limited by the information available about the analysis. The registry record does not define the subgroups, state how missing outcome measurements were handled, or explain whether the displayed participants constitute the full analysis population. These omissions make it difficult to judge whether the intervals account for every source of uncertainty in the observed comparisons. The results give evidence of separation in the posted data, but precision in the estimate is not the same as certainty about the treatment effect in other populations or about later outcomes.

11. Planning a Similar Trial: Sample Size

This is a planning illustration, not a re-evaluation of the original trial. It asks: if a new study wanted to detect a difference like the one observed, or a smaller one, how large would it need to be? It is deliberately not “observed power” of the finished trial, which is not a meaningful quantity.

The sample-size figures are planning illustrations based on the observed effect, not the trial’s original design justification. For these binary outcome comparisons, the figures are participants per arm, not total events. The calculation assumptions are a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. Each planning row uses a stated fraction of the observed effect as the effect to detect.

The 80% power column gives the illustrative number of participants per arm under those assumptions for an 80% chance of detecting the specified effect if that effect were the true one and the assumptions held. The 90% power column uses the same interpretation with a 90% chance. These are prospective planning quantities, not evidence that the completed study had a particular probability of finding a result. This is not observed power.

Rows based on 100% of the observed effect use the full observed contrast as the target. Rows based on 75% or 50% of the observed effect target smaller contrasts. Smaller effects are harder to distinguish from chance variation, so they generally require more participants for the same target power. The planning figures increase across those smaller-effect scenarios in the posted comparisons.

The registry record’s own original sample-size assumptions are not reported. The planning calculations should therefore be read only as illustrations of how sample size changes under the stated assumptions and observed-effect fractions. They do not show that the trial was designed around these exact calculations, nor do they establish that the enrolled or analyzed groups met a planned target. The group sizes in the primary outcome results are observed group counts; the planning figures are hypothetical per-arm requirements for future planning under the specified assumptions.

12. How the Sample Size Is Derived

Power is the probability that a study of a given size rejects the null hypothesis when a specific true effect exists. It depends on four things: the effect to detect, the variability of the outcome, the significance level (here a two-sided α of 0.05, so z_1−α/2 = 1.960) and the desired power (z_1−β = 0.842 for 80% and 1.282 for 90%).

Formula

n is the number of participants in each arm, p₀ and p₁ are the control and treatment proportions, and p̄ is their average.

Worked calculation for this trial

1. Control proportion p₀ = 0.971; treatment proportion p₁ = 0.625; average p̄ = 0.798.
2. First term: z_1−α/2 × √[2p̄(1−p̄)] = 1.96 × 0.5680 = 1.1133.
3. Second term: z_1−β × √[p₀(1−p₀) + p₁(1−p₁)] = 0.842 × 0.5128 = 0.4315.
4. n = (1.1133 + 0.4315)² / (-0.3456)² = 20.0, rounded up to 20 participants per arm for 80% power.

The smaller-effect rows in the table above repeat the same calculation with the effect multiplied by 0.75 and 0.5 (for ratios, applied to the logarithm of the ratio).

R code

alpha <- 0.05
z_a   <- qnorm(1 - alpha / 2)          # two-sided
p0 <- 0.970588235294118                          # control proportion
p1 <- 0.625                          # treatment proportion
n_per_arm <- function(power, frac = 1) {
  q1 <- p0 + (p1 - p0) * frac               # smaller effect = fraction of the observed difference
  pbar <- (p0 + q1) / 2
  z_b <- qnorm(power)
  ceiling(round((z_a * sqrt(2 * pbar * (1 - pbar)) + z_b * sqrt(p0 * (1 - p0) + q1 * (1 - q1)))^2 / (q1 - p0)^2, 6))
}
for (f in c(1, 0.75, 0.5))
  cat(sprintf("%3.0f%% of observed effect: n per arm = %s (80%% power), %s (90%% power)\n", 100 * f,
              format(n_per_arm(0.80, f), big.mark = ","), format(n_per_arm(0.90, f), big.mark = ",")))

# Check against R's built-in function (unrounded n per arm)
cat("power.prop.test:", round(power.prop.test(p1 = p0, p2 = p1, power = 0.80)$n, 1), "\n")

# Simulation: how often does the z-test reject at the 80%-power sample size?
set.seed(923013)
n    <- n_per_arm(0.80)
reps <- 20000
x0 <- rbinom(reps, n, p0); x1 <- rbinom(reps, n, p1)
ph <- (x0 + x1) / (2 * n)
z  <- ((x1 - x0) / n) / sqrt(ph * (1 - ph) * 2 / n)
cat(sprintf("Simulated power at n = %s per arm: %.3f (%d replicates)\n", format(n, big.mark = ","), mean(abs(z) > z_a, na.rm = TRUE), reps))

Output from running the code

100% of observed effect: n per arm = 20 (80% power), 27 (90% power)
 75% of observed effect: n per arm = 31 (80% power), 40 (90% power)
 50% of observed effect: n per arm = 53 (80% power), 70 (90% power)
power.prop.test: 20 
Simulated power at n = 20 per arm: 0.865 (20000 replicates)

The simulation draws many pairs of event counts at the planned sample size and counts how often the two-proportion z-test rejects the null. It should land close to the target power; at very small required sample sizes it can fall below it, because the normal approximation is rough there.

13. Multiplicity, Missing Data and Analysis Populations

The registry lists three outcome measures and one posted secondary outcome, minimal-residual-disease-free survival after cladribine and up to two courses of rituximab. The primary results include three comparisons against the same reference subgroup, each with an unadjusted p-value of <0.001. The record does not report a multiplicity procedure, a hierarchy among comparisons, or whether these contrasts were prespecified. Because several comparisons and outcomes can increase the chance of at least one false-positive result, the unadjusted p-values should be interpreted as individual comparison results, not as evidence that a family-wise error plan was applied.

The registry reports no analysis entries for the secondary outcome. Its event definition, analysis method, follow-up handling, and results are not reported in the registry record. The statistical analysis plan for the primary endpoint is also not reported, including whether the subgroup contrasts were planned or exploratory. The record does not state whether interim analyses were conducted or planned.

Missing-data handling is not reported. In particular, the registry does not explain how participants without all three 6-month assessments, with indeterminate results, or without a visit at the target time point were classified. It also does not provide an accounting of participants excluded from each outcome denominator or state whether missing values were imputed.

The analysis populations are not defined in the posted record. It does not state whether the primary comparison followed an intention-to-treat principle, whether participants were analyzed according to assigned group, or whether a per-protocol population was used. Although the study is identified as randomized, these analysis details cannot be assumed. The definitions of SubGroup 1 and SubGroup 2 are not reported, nor are subgroup-specific baseline characteristics. This limits interpretation of the four separate percentages and makes it difficult to assess their relationship to the randomized groups as a whole.

The original sample-size justification and any assumptions about expected outcome frequency or effect are also not reported. The planning illustrations based on the observed effect do not replace the trial’s original design rationale. The record does not give enough information to reconstruct these missing analysis decisions.

14. Safety Results

The registry reports serious adverse events as affected participants divided by participants at risk.

Deaths

Other (non-serious) adverse events

Participants with at least one non-serious event at or above the registry's 0% reporting threshold.

Most frequent serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: febrile neutropenia (12.0%), creatinine (5.0%), death not associated with ctcae term::death nos (5.0%), infection (5.0%), infection with unknown anc::lung (pneumonia) (5.0%).

The adverse-event summary gives counts of participants at risk and affected for serious events and for other events in six registry groups. For example, the immediate-treatment Cohort 1 SubGroup 1 entry lists 4 participants with serious events among 34 at risk, while the delayed-treatment Cohort 1 SubGroup 2 entry lists 5 among 30 at risk. These are group-level counts, not rates calculated. Deaths are listed separately in the group summaries; the record does not establish that each listed death was caused by treatment.

The most frequently listed serious-event terms include febrile neutropenia at 12.0%, creatinine at 5.0%, death not associated with a CTCAE term, death NOS, at 5.0%, infection at 5.0%, infection with unknown ANC, lung (pneumonia), at 5.0%, and dyspnea (shortness of breath) at 4.0%. These are registry-listed term frequencies. The record does not provide enough detail to infer causality, severity beyond the serious-event classification, timing, or whether terms overlap within participants.

Because the listed groups include randomized and non-randomized cohorts, their safety counts should not be treated as a direct randomized comparison. The registry does not report a comparative safety analysis or adjustment for differences in group size and follow-up. These summaries describe reported event counts; they do not establish whether one strategy has greater or lesser risk.

15. What the Result Does, and Does Not, Mean

The primary results describe the percentage meeting the registry’s 6-month minimal-residual-disease status in four Cohort 1 subgroup entries. The immediate-treatment entries are 97.1% among 34 participants and 62.5% among 32 participants. The delayed-treatment entries are 23.5% among 34 participants and 3.3% among 30 participants. Each of the three reported comparisons with the 97.1% reference subgroup has an unadjusted p-value of <0.001. These figures indicate clear separation among the specific groups as reported.

They do not establish that the subgroup differences are caused by treatment timing. The registry does not describe what distinguishes SubGroup 1 from SubGroup 2, and it does not provide baseline characteristics or adjusted analyses for the four entries. The investigator’s description says that the randomized groups are the focus, but the posted results show subgroup-level comparisons rather than a single combined estimate for each randomized strategy. The reason for this presentation is not reported in the registry record.

The endpoint indicates disease status according to three specified assessments at 6 months. It does not establish whether the status persists, whether participants later relapse, or how long any disease-free period lasts. Although the registry lists minimal-residual-disease-free survival as a secondary outcome, no analysis results for that measure are posted in the record. The primary result also does not answer questions about overall survival.

Statistical significance does not mean that every participant will have the same outcome, nor does it remove uncertainty around the size of a difference. The confidence intervals and modest subgroup counts matter when judging precision. The analysis also has unreported details concerning missing results, analysis populations, multiplicity, and subgroup definitions. The findings should therefore be interpreted as evidence about the posted 6-month subgroup comparisons, not as a complete or definitive account of longer-term outcomes or treatment effects in every patient group.

16. Why This Trial Matters Statistically

This trial raises a statistical question about timing: whether the 6-month disease-status result differs between a strategy using cladribine with immediate rituximab and a strategy reserving rituximab until at least 6 months after cladribine when minimal residual disease is detected. That question requires more than reading the largest and smallest percentages. It depends on the definition of the endpoint, how the groups were formed, and whether the analysis reflects the randomized allocation.

The registry’s outcome is built from three assessments, and the participant-level classification requires all three to be negative for hairy cells. This illustrates how endpoint definitions shape a trial result. A percentage based on a composite testing rule can differ from a result based on any single test. Clear reporting of missing and indeterminate test handling is therefore important, but those procedures are not reported in the registry record.

The posted results also show why subgroup reporting needs context. The two subgroup entries within each treatment strategy have different outcome percentages, yet the registry does not define the subgroup distinction. Without that information, readers cannot assess whether those entries represent planned clinical strata, a data-driven division, or something else. The randomized design is relevant, but randomized allocation does not make every separately reported subgroup contrast equivalent to an overall randomized comparison.

Finally, the record includes unadjusted p-values and confidence intervals but does not report a multiplicity plan or analysis populations. These omissions do not erase the descriptive differences; they limit how confidently the inferential results can be connected to a prespecified analysis. Statistically, the central lesson is that effect estimates, uncertainty, endpoint construction, and analysis transparency must be read together. The observed pattern is informative about the posted 6-month results, while important design and analysis details remain unavailable.

17. Limitations

• The posted summary statistics are the only data these results rest on; patient-level data, full protocols and statistical analysis plans are not available.
• Recalculated results are simple, unadjusted calculations from posted summaries. They do not replace the sponsor's prespecified analysis.
• Participant counts were reconstructed from posted percentages and arm sizes, so small rounding differences are possible.

Several limitations are specific to how this trial’s results are reported. First, the primary endpoint is assessed at 6 months, so it does not by itself describe durability. The registry lists a secondary minimal-residual-disease-free survival outcome after cladribine and up to two courses of rituximab, but no secondary analysis results are posted.

Second, the primary outcome results are presented as four subgroup entries. The registry does not define the subgroup labels or explain why the results are split this way. The outcome description says Cohort 2 and Cohort 3 are not included because the investigator is comparing randomized groups, but it does not give a combined randomized-group estimate. This makes the relationship between the displayed subgroup contrasts and an overall treatment-strategy comparison difficult to assess.

Third, the record does not report baseline characteristics by subgroup, missing-data handling, the analysis population, or whether the displayed denominators include all randomized participants with available results. It also does not state how incomplete or indeterminate bone marrow, blood flow cytometry, or biopsy results were treated. These gaps limit assessment of possible selection and classification effects.

Fourth, the three p-values are unadjusted, and the registry does not report a multiplicity plan or whether the subgroup analyses were prespecified. The original sample-size justification and interim-analysis plan are not reported. The sample-size illustrations based on observed effects cannot fill those gaps.

Finally, the registry includes safety summaries from randomized and non-randomized groups, but does not provide a comparative safety analysis or establish event causality. The record’s active, not recruiting status also means the posted record should not be read as confirmation that all study follow-up is complete. These limitations are about what the registry record reports; they do not resolve the underlying clinical question.

18. Related Tutorials

19. Related Statistical Calculators

20. Sources

• ClinicalTrials.gov: Cladribine With Simultaneous or Delayed Rituximab to Treat Hairy Cell Leukemia — NCT00923013.
• Registry record last updated 2026-08-18; status last verified 2026-07.
• Results first posted 2025-08-08.
• Data retrieved from ClinicalTrials.gov on 2026-11-09.
• Group sizes, means, event counts and sponsor-reported p-values are reproduced as posted. Effect estimates, confidence intervals and p-values not attributed to the sponsor are independently calculated from the posted summary statistics.

21. Record Summary

The registry record describes a Phase 2, randomized, parallel-group, unmasked study of cladribine with immediate or delayed rituximab for Hairy Cell Leukemia. Listed enrollment is 175, and the status is active, not recruiting. The primary outcome is the percentage meeting the registry’s minimal-residual-disease status at restaging 6 months after treatment starts, based on bone marrow and blood flow cytometry and core-biopsy histochemistry.

Four Cohort 1 subgroup results are posted, with percentages ranging from 97.1% to 3.3%. Three unadjusted comparisons against the 97.1% reference subgroup have p-values of <0.001. The record does not define the subgroup labels, report analysis populations or missing-data methods, or give a multiplicity plan. It lists one secondary outcome, minimal-residual-disease-free survival after cladribine and up to two courses of rituximab, but no analysis entries are posted for it. The findings describe the stated 6-month outcome and do not directly report longer-term disease control or survival.